U.S. patent application number 17/720582 was filed with the patent office on 2022-08-25 for joint coding of chroma residual and filtering in video processing.
The applicant listed for this patent is Bytedance Inc.. Invention is credited to Jizheng XU, Kai ZHANG, Li ZHANG, Weijia ZHU.
Application Number | 20220272347 17/720582 |
Document ID | / |
Family ID | 1000006304551 |
Filed Date | 2022-08-25 |
United States Patent
Application |
20220272347 |
Kind Code |
A1 |
ZHU; Weijia ; et
al. |
August 25, 2022 |
JOINT CODING OF CHROMA RESIDUAL AND FILTERING IN VIDEO
PROCESSING
Abstract
An example method of video processing includes determining, for
a conversion between a chroma block of a video and a bitstream
representation of the video, applicability of a deblocking filter
process to at least some samples at an edge of the chroma block
based on a mode of joint coding of chroma residuals for the chroma
block. The method also includes performing the conversion based on
the determining.
Inventors: |
ZHU; Weijia; (San Diego,
CA) ; ZHANG; Li; (San Diego, CA) ; XU;
Jizheng; (San Diego, CA) ; ZHANG; Kai; (San
Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Bytedance Inc. |
Los Angeles |
CA |
US |
|
|
Family ID: |
1000006304551 |
Appl. No.: |
17/720582 |
Filed: |
April 14, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/US2020/055329 |
Oct 13, 2020 |
|
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17720582 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04N 19/117 20141101;
H04N 19/186 20141101; H04N 19/132 20141101; H04N 19/176
20141101 |
International
Class: |
H04N 19/132 20060101
H04N019/132; H04N 19/117 20060101 H04N019/117; H04N 19/186 20060101
H04N019/186; H04N 19/176 20060101 H04N019/176 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 14, 2019 |
CN |
PCT/CN2019/111115 |
Claims
1. A method of processing video data, comprising: determining,
during a conversion between a current block of a video and a
bitstream of the video, a first chroma quantization parameter used
in a deblocking filtering process applied to at least some samples
along an edge of the current block based on a second chroma
quantization parameter used in a scaling process and a quantization
parameter offset associated with a bit depth; and performing the
conversion based on the determining, wherein the scaling process
comprises: applying a quantization on at least some coefficients
representing the current block during encoding; or applying a
dequantization on at least some coefficients from the bitstream
during decoding.
2. The method of claim 1, wherein the first chroma quantization
parameter is equal to the second quantization parameter used in the
scaling process minus the quantization parameter offset associated
with the bit depth.
3. The method of claim 1, wherein the first chroma quantization
parameter is used for deblocking samples along a first side of the
edge of the current block, and the first side is referred to as
P-side, the P-side comprising samples located above the edge in
case the edge is a horizontal boundary or to the left of the edge
in case the boundary is a vertical boundary, or wherein the first
chroma quantization parameter is used for deblocking samples along
a second side of the edge of the current block, and the second side
is referred to as Q-side, the Q-side comprising samples located
below the edge in case the edge is a horizontal boundary or to the
right of the edge in case the edge is a vertical boundary.
4. The method of claim 1, wherein in case a value of a first
variable indicating a mode of joint coding of chroma Cb residuals
and chroma Cr residuals is equal to 2, the first chroma
quantization parameter is equal to the second quantization
parameter for the mode of joint coding of chroma Cb residuals and
chroma Cr residuals used in the scaling process minus quantization
parameter offset associated with the bit depth.
5. The method of claim 4, wherein the second chroma quantization
parameter of P-side is equal to
Clip3(-QpBdOffset.sub.C,63,qP.sub.CbCr(P)+pps_cbcr_qp_offset(P)+slice_cbc-
r_qp_offset(P)+CuQp Offset.sub.CbCr(P))+QpBdOffset.sub.C, the
second chroma quantization parameter of Q-side is equal to
Clip3(-QpBdOffset.sub.C,63,qP.sub.CbCr(Q)+pps_cbcr_qp_offset(Q)+slice_cbc-
r_qp_offset(Q)+CuQp Offset.sub.CbCr(Q))+QpBdOffset.sub.C, and the
first chroma quantization parameter of P-side is equal to
Clip3(-QpBdOffset.sub.C,63,qP.sub.CbCr(P)+pps_cbcr_qp_offset(P)+slice_cbc-
r_qp_offset(P)+CuQp Offset.sub.CbCr(P)), the first chroma
quantization parameter of Q-side is equal to
Clip3(-QpBdOffset.sub.C,63,qP.sub.CbCr(Q)+pps_cbcr_qp_offset(Q)+slice_cbc-
r_qp_offset(Q)+CuQp Offset.sub.CbCr(Q)), and wherein qP.sub.CbCr(P)
and qP.sub.CbCr(Q) are outputs of a chroma quantization parameter
table operation based on a luma chroma quantization parameter,
pps_cbcr_qp_offset(P) and pps_cbcr_qp_offset(Q) are chroma
quantization parameter offsets at a picture level,
slice_cbcr_qp_offset(P) and slice_cbcr_qp_offset(Q) are chroma
quantization parameter offsets at a slice level,
CuQpOffset.sub.CbCr(P) and CuQpOffset.sub.CbCr(Q) are chroma
quantization parameter offsets at a block level, and
QpBdOffset.sub.C is the quantization parameter offset associated
with a bit depth.
6. The method of claim 5, wherein a second variable used to derive
deblocking variables .beta. and t.sub.C is equal to (the first
chroma quantization parameter of P-side+the first chroma
quantization parameter of Q-side+1)>>1.
7. The method of claim 4, wherein in case a value of the first
variable indicating the mode of joint coding of chroma Cb residuals
and chroma Cr residuals is not equal to 2, the first chroma
quantization parameter is equal to the second quantization
parameter for a first chroma Cb component used in the scaling
process minus quantization parameter offset associated with the bit
depth or the first chroma quantization parameter is equal to the
second quantization parameter for a second chroma Cr component used
in the scaling process minus quantization parameter offset
associated with the bit depth.
8. The method of claim 1, wherein the second quantization parameter
used in the scaling process is derived at least based on chroma
quantization parameter offsets at a picture level, a slice level
and a block level.
9. The method of claim 1, wherein the conversion includes encoding
the video into the bitstream.
10. The method of claim 1, wherein the conversion includes decoding
the video from the bitstream.
11. An apparatus for processing video data comprising a processor
and a non-transitory memory with instructions thereon, wherein the
instructions upon execution by the processor, cause the processor
to: determine, during a conversion between a current block of a
video and a bitstream of the video, a first chroma quantization
parameter used in a deblocking filtering process applied to at
least some samples along an edge of the current block based on a
second chroma quantization parameter used in a scaling process and
a quantization parameter offset associated with a bit depth; and
perform the conversion based on the determination, wherein the
scaling process comprises: applying a quantization on at least some
coefficients representing the current block during encoding; or
applying a dequantization on at least some coefficients from the
bitstream during decoding.
12. The apparatus of claim 11, wherein the first chroma
quantization parameter is equal to the second quantization
parameter used in the scaling process minus the quantization
parameter offset associated with the bit depth; and wherein the
first chroma quantization parameter is used for deblocking samples
along a first side of the edge of the current block, and the first
side is referred to as P-side, the P-side comprising samples
located above the edge in case the edge is a horizontal boundary or
to the left of the edge in case the boundary is a vertical
boundary, or wherein the first chroma quantization parameter is
used for deblocking samples along a second side of the edge of the
current block, and the second side is referred to as Q-side, the
Q-side comprising samples located below the edge in case the edge
is a horizontal boundary or to the right of the edge in case the
edge is a vertical boundary.
13. The apparatus of claim 11, wherein in case a value of a first
variable indicating a mode of joint coding of chroma Cb residuals
and chroma Cr residuals is equal to 2, the first chroma
quantization parameter is equal to the second quantization
parameter for the mode of joint coding of chroma Cb residuals and
chroma Cr residuals used in the scaling process minus quantization
parameter offset associated with the bit depth; wherein the second
chroma quantization parameter of P-side is equal to
Clip3(-QpBdOffset.sub.C,63,qP.sub.CbCr(P)+pps_cbcr_qp_offset(P)+-
slice_cbcr_qp_offset(P)+CuQp Offset.sub.CbCr(P))+QpBdOffset.sub.C,
the second chroma quantization parameter of Q-side is equal to
Clip3(-QpBdOffset.sub.C,63,qP.sub.CbCr(Q)+pps_cbcr_qp_offset(Q)+slice_cbc-
r_qp_offset(Q)+CuQp Offset.sub.CbCr(Q))+QpBdOffset.sub.C, and the
first chroma quantization parameter of P-side is equal to
Clip3(-QpBdOffset.sub.C,63,qP.sub.CbCr(P)+pps_cbcr_qp_offset(P)+slice_cbc-
r_qp_offset(P)+CuQp Offset.sub.CbCr(P)), the first chroma
quantization parameter of Q-side is equal to
Clip3(-QpBdOffset.sub.C,63,qP.sub.CbCr(Q)+pps_cbcr_qp_offset(Q)+slice_cbc-
r_qp_offset(Q)+CuQp Offset.sub.CbCr(Q)), and wherein qP.sub.CbCr(P)
and qP.sub.CbCr(Q) are outputs of a chroma quantization parameter
table operation based on a luma chroma quantization parameter,
pps_cbcr_qp_offset(P) and pps_cbcr_qp_offset(Q) are chroma
quantization parameter offsets at a picture level,
slice_cbcr_qp_offset(P) and slice_cbcr_qp_offset(Q) are chroma
quantization parameter offsets at a slice level,
CuQpOffset.sub.CbCr(P) and CuQpOffset.sub.CbCr(Q) are chroma
quantization parameter offsets at a block level, and
QpBdOffset.sub.C is the quantization parameter offset associated
with a bit depth; wherein a second variable used to derive
deblocking variables .beta. and t.sub.C is equal to (the first
chroma quantization parameter of P-side+the first chroma
quantization parameter of Q-side+1)>>1; and wherein in case a
value of the first variable indicating the mode of joint coding of
chroma Cb residuals and chroma Cr residuals is not equal to 2, the
first chroma quantization parameter is equal to the second
quantization parameter for a first chroma Cb component used in the
scaling process minus quantization parameter offset associated with
the bit depth or the first chroma quantization parameter is equal
to the second quantization parameter for a second chroma Cr
component used in the scaling process minus quantization parameter
offset associated with the bit depth.
14. The apparatus of claim 11, wherein the second quantization
parameter used in the scaling process is derived at least based on
chroma quantization parameter offsets at a picture level, a slice
level and a block level.
15. A non-transitory computer-readable storage medium storing
instructions that cause a processor to: determine, during a
conversion between a current block of a video and a bitstream of
the video, a first chroma quantization parameter used in a
deblocking filtering process applied to at least some samples along
an edge of the current block based on a second chroma quantization
parameter used in a scaling process and a quantization parameter
offset associated with a bit depth; and perform the conversion
based on the determination, wherein the scaling process comprises:
applying a quantization on at least some coefficients representing
the current block during encoding; or applying a dequantization on
at least some coefficients from the bitstream during decoding.
16. The non-transitory computer-readable storage medium of claim
15, wherein the first chroma quantization parameter is equal to the
second quantization parameter used in the scaling process minus the
quantization parameter offset associated with the bit depth;
wherein the first chroma quantization parameter is used for
deblocking samples along a first side of the edge of the current
block, and the first side is referred to as P-side, the P-side
comprising samples located above the edge in case the edge is a
horizontal boundary or to the left of the edge in case the boundary
is a vertical boundary, or wherein the first chroma quantization
parameter is used for deblocking samples along a second side of the
edge of the current block, and the second side is referred to as
Q-side, the Q-side comprising samples located below the edge in
case the edge is a horizontal boundary or to the right of the edge
in case the edge is a vertical boundary; and wherein the second
quantization parameter used in the scaling process is derived at
least based on chroma quantization parameter offsets at a picture
level, a slice level and a block level.
17. The non-transitory computer-readable storage medium of claim
15, wherein in case a value of a first variable indicating a mode
of joint coding of chroma Cb residuals and chroma Cr residuals is
equal to 2, the first chroma quantization parameter is equal to the
second quantization parameter for the mode of joint coding of
chroma Cb residuals and chroma Cr residuals used in the scaling
process minus quantization parameter offset associated with the bit
depth; wherein the second chroma quantization parameter of P-side
is equal to
Clip3(-QpBdOffset.sub.C,63,qP.sub.CbCr(P)+pps_cbcr_qp_offset(P)+slice_cbc-
r_qp_offset(P)+CuQp Offset.sub.CbCr(P))+QpBdOffset.sub.C, the
second chroma quantization parameter of Q-side is equal to
Clip3(-QpBdOffset.sub.C,63,qP.sub.CbCr(Q)+pps_cbcr_qp_offset(Q)+slice_cbc-
r_qp_offset(Q)+CuQp Offset.sub.CbCr(Q))+QpBdOffset.sub.C, and the
first chroma quantization parameter of P-side is equal to
Clip3(-QpBdOffset.sub.C,63,qP.sub.CbCr(P)+pps_cbcr_qp_offset(P)+slice_cbc-
r_qp_offset(P)+CuQp Offset.sub.CbCr(P)) , the first chroma
quantization parameter of Q-side is equal to
Clip3(-QpBdOffset.sub.C,63,qP.sub.CbCr(Q)+pps_cbcr_qp_offset(Q)+slice_cbc-
r_qp_offset(Q)+CuQp Offset.sub.CbCr(Q)), and wherein qP.sub.CbCr(P)
and qP.sub.CbCr(Q) are outputs of a chroma quantization parameter
table operation based on a luma chroma quantization parameter,
pps_cbcr_qp_offset(P) and pps_cbcr_qp_offset(Q) are chroma
quantization parameter offsets at a picture level,
slice_cbcr_qp_offset(P) and slice_cbcr_qp_offset(Q) are chroma
quantization parameter offsets at a slice level,
CuQpOffset.sub.CbCr(P) and CuQpOffset.sub.CbCr(Q) are chroma
quantization parameter offsets at a block level, and
QpBdOffset.sub.C is the quantization parameter offset associated
with a bit depth; wherein a second variable used to derive
deblocking variables .beta. and t.sub.C is equal to (the first
chroma quantization parameter of P-side+the first chroma
quantization parameter of Q-side30 1)>>1; and wherein in case
a value of the first variable indicating the mode of joint coding
of chroma Cb residuals and chroma Cr residuals is not equal to 2,
the first chroma quantization parameter is equal to the second
quantization parameter for a first chroma Cb component used in the
scaling process minus quantization parameter offset associated with
the bit depth or the first chroma quantization parameter is equal
to the second quantization parameter for a second chroma Cr
component used in the scaling process minus quantization parameter
offset associated with the bit depth.
18. A non-transitory computer-readable recording medium storing a
bitstream of a video which is generated by a method performed by a
video processing apparatus, wherein the method comprises:
determining, for a current block of a video, a first chroma
quantization parameter used in a deblocking filtering process
applied to at least some samples along an edge of the current block
based on a second chroma quantization parameter used in a scaling
process and a quantization parameter offset associated with a bit
depth; and generating the bitstream based on the determination;
wherein the scaling process comprises: applying a quantization on
at least some coefficients representing the current block during
encoding; or applying a dequantization on at least some
coefficients from the bitstream during decoding.
19. The non-transitory computer-readable recording medium of claim
18, wherein the first chroma quantization parameter is equal to the
second quantization parameter used in the scaling process minus the
quantization parameter offset associated with the bit depth;
wherein the first chroma quantization parameter is used for
deblocking samples along a first side of the edge of the current
block, and the first side is referred to as P-side, the P-side
comprising samples located above the edge in case the edge is a
horizontal boundary or to the left of the edge in case the boundary
is a vertical boundary, or wherein the first chroma quantization
parameter is used for deblocking samples along a second side of the
edge of the current block, and the second side is referred to as
Q-side, the Q-side comprising samples located below the edge in
case the edge is a horizontal boundary or to the right of the edge
in case the edge is a vertical boundary; and wherein the second
quantization parameter used in the scaling process is derived at
least based on chroma quantization parameter offsets at a picture
level, a slice level and a block level.
20. The non-transitory computer-readable recording medium of claim
18, wherein in case a value of a first variable indicating a mode
of joint coding of chroma Cb residuals and chroma Cr residuals is
equal to 2, the first chroma quantization parameter is equal to the
second quantization parameter for the mode of joint coding of
chroma Cb residuals and chroma Cr residuals used in the scaling
process minus quantization parameter offset associated with the bit
depth; wherein the second chroma quantization parameter of P-side
is equal to
Clip3(-QpBdOffset.sub.C,63,qP.sub.CbCr(P)+pps_cbcr_qp_offset(P)+slice_cbc-
r_qp_offset(P)+CuQp Offset.sub.CbCr(P))+QpBdOffset.sub.C, the
second chroma quantization parameter of Q-side is equal to
Clip3(-QpBdOffset.sub.C,63,qP.sub.CbCr(Q)
pps_cbcr_qp_offset(Q)+slice_cbcr_qp_offset(Q)+CuQp
Offset.sub.CbCr(Q))+QpBdOffset.sub.C, and the first chroma
quantization parameter of P-side is equal to
Clip3(-QpBdOffset.sub.C,63,qP.sub.CbCr(P)+pps_cbcr_qp_offset(P)+slice_cbc-
r_qp_offset(P)+CuQp Offset.sub.CbCr(P)), the first chroma
quantization parameter of Q-side is equal to
Clip3(-QpBdOffset.sub.C,63,qP.sub.CbCr(Q)+pps_cbcr_qp_offset(Q)+slice_cbc-
r_qp_offset(Q)+CuQp Offset.sub.CbCr(Q)), and wherein qP.sub.CbCr(P)
and qP.sub.CbCr(Q) are outputs of a chroma quantization parameter
table operation based on a luma chroma quantization parameter,
pps_cbcr_qp_offset(P) and pps_cbcr_qp_offset(Q) are chroma
quantization parameter offsets at a picture level,
slice_cbcr_qp_offset(P) and slice_cbcr_qp_offset(Q) are chroma
quantization parameter offsets at a slice level,
CuQpOffset.sub.CbCr(P) and CuQpOffset.sub.CbCr(Q) are chroma
quantization parameter offsets at a block level, and
QpBdOffset.sub.C is the quantization parameter offset associated
with a bit depth; wherein a second variable used to derive
deblocking variables .beta. and t.sub.C is equal to (the first
chroma quantization parameter of P-side+the first chroma
quantization parameter of Q-side+1)>>1; and wherein in case a
value of the first variable indicating the mode of joint coding of
chroma Cb residuals and chroma Cr residuals is not equal to 2, the
first chroma quantization parameter is equal to the second
quantization parameter for a first chroma Cb component used in the
scaling process minus quantization parameter offset associated with
the bit depth or the first chroma quantization parameter is equal
to the second quantization parameter for a second chroma Cr
component used in the scaling process minus quantization parameter
offset associated with the bit depth.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of International Patent
Application No. PCT/US2020/055329, filed on Oct. 13, 2020, which
claims the priority to and benefits of International Patent
Application No. PCT/CN2019/111115, filed on Oct. 14, 2019. All the
aforementioned patent applications are hereby incorporated by
reference in their entireties.
TECHNICAL FIELD
[0002] This patent document relates to video coding techniques,
devices and systems.
BACKGROUND
[0003] Currently, efforts are underway to improve the performance
of current video codec technologies to provide better compression
ratios or provide video coding and decoding schemes that allow for
lower complexity or parallelized implementations. Industry experts
have recently proposed several new video coding tools and tests are
currently underway for determining their effectivity.
SUMMARY
[0004] Devices, systems and methods related to digital video
coding, and specifically, to management of motion vectors are
described. The described methods may be applied to existing video
coding standards (e.g., High Efficiency Video Coding (HEVC) or
Versatile Video Coding) and future video coding standards or video
codecs.
[0005] In one representative aspect, the disclosed technology may
be used to provide a method for video processing. This method
includes determining, for a conversion between a chroma block of a
video and a bitstream representation of the video, applicability of
a deblocking filter process to at least some samples at an edge of
the chroma block based on a mode of joint coding of chroma
residuals for the chroma block. The method also includes performing
the conversion based on the determining.
[0006] In another representative aspect, the disclosed technology
may be used to provide a method for video processing. This method
includes determining, for a conversion between a current block of a
video and a bitstream representation of the video, a chroma
quantization parameter used in a deblocking filtering process
applied to at least some samples at an edge of the current block
based on information of a corresponding transform block of the
current block. The method also includes performing the conversion
based on the determining.
[0007] In another representative aspect, the disclosed technology
may be used to provide a method for video processing. This method
includes performing a conversion between a current block of a video
and a bitstream representation of the video. During the conversion,
a first chroma quantization parameter used in a deblocking
filtering process applied to at least some samples along an edge of
the current block is based on a second chroma quantization
parameter used in a scaling process and a quantization parameter
offset associated with a bit depth.
[0008] In another representative aspect, the disclosed technology
may be used to provide a method for video processing. This method
includes performing a conversion between a video comprising one or
more coding units and a bitstream representation of the video. The
bitstream representation conforms to a format rule that specifies
that chroma quantization parameters are included in the bitstream
representation at a coding unit level or a transform unit level
according to The format rule.
[0009] In another representative aspect, the disclosed technology
may be used to provide a method for video processing. This method
includes performing a conversion between a block of a video and a
bitstream representation of the video. The bitstream representation
conforms to a format rule specifying that whether a joint coding of
chroma residuals mode is applicable to the block is indicated at a
coding unit level in the bitstream representation.
[0010] In another representative aspect, the disclosed technology
may be used to provide a method for video processing. This method
includes performing a conversion between a video unit and a coded
representation of the video unit, wherein, during the conversion, a
deblocking filter is used on boundaries of the video unit such that
when a chroma quantization parameter (QP) table is used to derive
parameters of the deblocking filter, processing by the chroma QP
table is performed on individual chroma QP values.
[0011] In another representative aspect, the disclosed technology
may be used to provide another method for video processing. This
method includes performing a conversion between a video unit and a
bitstream representation of the video unit, wherein, during the
conversion, a deblocking filter is used on boundaries of the video
unit such that chroma QP offsets are used in the deblocking filter,
wherein the chroma QP offsets are at
picture/slice/tile/brick/subpicture level.
[0012] In another representative aspect, the disclosed technology
may be used to provide another method for video processing. This
method includes performing a conversion between a video unit and a
bitstream representation of the video unit, wherein, during the
conversion, a deblocking filter is used on boundaries of the video
unit such that chroma QP offsets are used in the deblocking filter,
wherein information pertaining to a same luma coding unit is used
in the deblocking filter and for deriving a chroma QP offset.
[0013] In another representative aspect, the disclosed technology
may be used to provide another method for video processing. This
method includes performing a conversion between a video unit and a
bitstream representation of the video unit, wherein, during the
conversion, a deblocking filter is used on boundaries of the video
unit such that chroma QP offsets are used in the deblocking filter,
wherein an indication of enabling usage of the chroma QP offsets is
signaled in the bitstream representation.
[0014] In another representative aspect, the disclosed technology
may be used to provide another method for video processing. This
method includes performing a conversion between a video unit and a
bitstream representation of the video unit, wherein, during the
conversion, a deblocking filter is used on boundaries of the video
unit such that chroma QP offsets are used in the deblocking filter,
wherein the chroma QP offsets used in the deblocking filter are
identical of whether JCCR coding method is applied on a boundary of
the video unit or a method different from the JCCR coding method is
applied on the boundary of the video unit.
[0015] In another representative aspect, the disclosed technology
may be used to provide another method for video processing. This
method includes performing a conversion between a video unit and a
bitstream representation of the video unit, wherein, during the
conversion, a deblocking filter is used on boundaries of the video
unit such that chroma QP offsets are used in the deblocking filter,
wherein a boundary strength (BS) of the deblocking filter is
calculated without comparing reference pictures and/or a number of
motion vectors (MVs) associated with the video unit at a P side
boundary with reference pictures of the video unit at a Q side
boundary.
[0016] Further, in a representative aspect, an apparatus in a video
system comprising a processor and a non-transitory memory with
instructions thereon is disclosed. The instructions upon execution
by the processor, cause the processor to implement any one or more
of the disclosed methods.
[0017] Additionally, in a representative aspect, a video decoding
apparatus comprising a processor configured to implement any one or
more of the disclosed methods.
[0018] In another representative aspect, a video encoding apparatus
comprising a processor configured to implement any one or more of
the disclosed methods.
[0019] Also, a computer program product stored on a non-transitory
computer readable media, the computer program product including
program code for carrying out any one or more of the disclosed
methods is disclosed.
[0020] The above and other aspects and features of the disclosed
technology are described in greater detail in the drawings, the
description and the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 shows an example of an overall processing flow of a
blocking deblocking filter process.
[0022] FIG. 2 shows an example of a flow diagram of a Bs
calculation.
[0023] FIG. 3 shows an example of a referred information for Bs
calculation at CTU boundary.
[0024] FIG. 4 shows an example of pixels involved in filter on/off
decision and strong/weak filter selection.
[0025] FIG. 5 shows an example of an overall processing flow of
deblocking filter process in VVC.
[0026] FIG. 6 shows an example of a luma deblocking filter process
in VVC.
[0027] FIG. 7 shows an example of a chroma deblocking filter
process in VVC
[0028] FIG. 8 shows an example of a filter length determination for
sub PU boundaries.
[0029] FIG. 9A shows an example of center positions of a chroma
block.
[0030] FIG. 9B shows another example of center positions of a
chroma block.
[0031] FIG. 10 shows examples of blocks at P side and Q side.
[0032] FIG. 11 shows examples of usage of a luma block's decoded
information.
[0033] FIG. 12 is a block diagram of an example of a hardware
platform for implementing a visual media decoding or a visual media
encoding technique described in the present document.
[0034] FIG. 13 shows a flowchart of an example method for video
coding.
[0035] FIG. 14A shows an example of Placement of CC-ALF with
respect to other loop filters (b) Diamond shaped filter.
[0036] FIG. 14B shows an example of Placement of CC-ALF with
respect to Diamond shaped filter.
[0037] FIG. 15 is a block diagram that illustrates an example video
coding system.
[0038] FIG. 16 is a block diagram that illustrates an encoder in
accordance with some embodiments of the present disclosure.
[0039] FIG. 17 is a block diagram that illustrates a decoder in
accordance with some embodiments of the present disclosure.
[0040] FIG. 18 is a block diagram of an example video processing
system in which disclosed techniques may be implemented.
[0041] FIG. 19 is a flowchart representation of a method for video
processing in accordance with the present technology.
[0042] FIG. 20 is a flowchart representation of another method for
video processing in accordance with the present technology.
[0043] FIG. 21 is a flowchart representation of another method for
video processing in accordance with the present technology.
[0044] FIG. 22 is a flowchart representation of another method for
video processing in accordance with the present technology.
[0045] FIG. 23 is a flowchart representation of yet another method
for video processing in accordance with the present technology.
DETAILED DESCRIPTION
1. Video Coding in HEVC/H.265
[0046] Video coding standards have evolved primarily through the
development of the well-known ITU-T and ISO/IEC standards. The
ITU-T produced H.261 and H.263, ISO/IEC produced MPEG-1 and MPEG-4
Visual, and the two organizations jointly produced the H.262/MPEG-2
Video and H.264/MPEG-4 Advanced Video Coding (AVC) and H.265/HEVC
standards. Since H.262, the video coding standards are based on the
hybrid video coding structure wherein temporal prediction plus
transform coding are utilized. To explore the future video coding
technologies beyond HEVC, Joint Video Exploration Team (JVET) was
founded by VCEG and MPEG jointly in 2015. Since then, many new
methods have been adopted by JVET and put into the reference
software named Joint Exploration Model (JEM). In April 2018, the
Joint Video Expert Team (JVET) between VCEG (Q6/16) and ISO/IEC
JTC1 SC29/WG11 (MPEG) was created to work on the VVC standard
targeting at 50% bitrate reduction compared to HEVC.
2.1. Deblocking Scheme in HEVC
[0047] A deblocking filter process is performed for each CU in the
same order as the decoding process. First, vertical edges are
filtered (horizontal filtering), then horizontal edges are filtered
(vertical filtering). Filtering is applied to 8.times.8 block
boundaries which are determined to be filtered, for both luma and
chroma components. 4.times.4 block boundaries are not processed in
order to reduce the complexity.
[0048] FIG. 1 illustrates the overall processing flow of deblocking
filter process. A boundary can have three filtering status: no
filtering, weak filtering and strong filtering. Each filtering
decision is based on boundary strength, Bs, and threshold values,
.beta. and t.sub.C.
[0049] Three kinds of boundaries may be involved in the filtering
process: CU boundary, TU boundary and PU boundary. CU boundaries,
which are outer edges of CU, are always involved in the filtering
since CU boundaries are always also TU boundary or PU boundary.
When PU shape is 2N.times.N (N>4) and RQT depth is equal to 1,
TU boundary at 8.times.8 block grid and PU boundary between each PU
inside CU are involved in the filtering. One exception is that when
the PU boundary is inside the TU, the boundary is not filtered.
2.1.1. Boundary Strength Calculation
[0050] Generally speaking, boundary strength (Bs) reflects how
strong filtering is needed for the boundary. If Bs is large, strong
filtering should be considered.
[0051] Let P and Q be defined as blocks which are involved in the
filtering, where P represents the block located in left (vertical
edge case) or above (horizontal edge case) side of the boundary and
Q represents the block located in right (vertical edge case) or
above (horizontal edge case) side of the boundary. FIG. 2
illustrates how the Bs value is calculated based on the intra
coding mode, existence of non-zero transform coefficients and
motion information, reference picture, number of motion vectors and
motion vector difference.
[0052] Bs is calculated on a 4.times.4 block basis, but it is
re-mapped to an 8.times.8 grid. The maximum of the two values of Bs
which correspond to 8 pixels consisting of a line in the 4.times.4
grid is selected as the Bs for boundaries in the 8.times.8
grid.
[0053] In order to reduce line buffer memory requirement, only for
CTU boundary, information in every second block (4.times.4 grid) in
left or above side is re-used as depicted in FIG. 3.
2.1.2. .beta. and t.sub.C Decision
[0054] Threshold values .beta. and t.sub.C which involving in
filter on/off decision, strong and weak filter selection and weak
filtering process are derived based on luma quantization parameter
of P and Q blocks, QP.sub.P and QP.sub.Q, respectively. Q used to
derive .beta. and t.sub.C is calculated as follows.
Q = ( ( Q .times. P P + Q .times. P Q + 1 ) 1 ) . ##EQU00001##
[0055] A variable .beta. is derived as shown in Table 1, based on
Q. If Bs is greater than 1, the variable t.sub.C is specified as
Table 1 with Clip3(0, 55, Q+2) as input. Otherwise (BS is equal or
less than 1), the variable t.sub.C is specified as Table 1 with Q
as input.
TABLE-US-00001 TABLE 1 Derivation of threshold variables .beta. and
t.sub.C from input Q Q 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
18 .beta. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 6 7 8 tc 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 1 Q 19 20 21 22 23 24 25 26 27 28 29 30 31 32
33 34 35 36 37 .beta. 9 10 11 12 13 14 15 16 17 18 20 22 24 26 28
30 32 34 36 tc 1 1 1 1 1 1 1 1 2 2 2 2 3 3 3 3 4 4 4 Q 38 39 40 41
42 43 44 45 46 47 48 49 50 51 52 53 54 55 .beta. 38 40 42 44 46 48
50 52 54 56 58 60 62 64 64 64 64 64 tc 5 5 6 6 7 8 9 9 10 10 11 11
12 12 13 13 14 14
2.1.3. Filter On/Off Decision for 4 Lines
[0056] Filter on/off decision is done for four lines as a unit.
FIG. 4 illustrates the pixels involving in filter on/off decision.
The 6 pixels in the two red boxes for the first four lines are used
to determine filter on/off for 4 lines. The 6 pixels in two red
boxes for the second 4 lines are used to determine filter on/off
for the second four lines.
[0057] If dp0+dq0+dp3+dq3<.beta., filtering for the first four
lines is turned on and strong/weak filter selection process is
applied. Each variable is derived as follows.
dp .times. .times. 0 = p 2 , 0 - 2 * p 1 , 0 + p 0 , 0 , dp .times.
.times. 3 = p 2 , 3 - 2 * p 1 , 3 + p 0 , 3 , dp .times. .times. 4
= p 2 , 4 - 2 * p 1 , 4 + p 0 , 4 , dp .times. .times. 7 = p 2 , 7
- 2 * p 1 , 7 + p 0 , 7 ##EQU00002## dq .times. .times. 0 = q 2 , 0
- 2 * q 1 , 0 + q 0 , 0 , dq .times. .times. 3 = q 2 , 3 - 2 * q 1
, 3 + q 0 , 3 , dq .times. .times. 4 = q 2 , 4 - 2 * q 1 , 4 + q 0
, 4 , dq .times. .times. 7 = q 2 , 7 - 2 * q 1 , 7 + q 0 , 7
##EQU00002.2##
[0058] If the condition is not met, no filtering is done for the
first 4 lines. Additionally, if the condition is met, dE, dEp1 and
dEp2 are derived for weak filtering process. The variable dE is set
equal to 1. If dp0+dp3<+(.beta.>>1))>>3, the
variable dEp1 is set equal to 1. If
dq0+dq3<(.beta.(.beta.>>1))>>3, the variable dEq1 is
set equal to 1.
[0059] For the second four lines, decision is made in a same
fashion with above.
2.1.4. Strong/Weak Filter Selection for 4 Lines
[0060] After the first four lines are determined to filtering on in
filter on/off decision, if following two conditions are met, strong
filter is used for filtering of the first four lines. Otherwise,
weak filter is used for filtering. Involving pixels are same with
those used for filter on/off decision as depicted in FIG. 4.
1 ) .times. .times. 2 * ( dp .times. .times. 0 + dq .times. .times.
0 ) < ( .beta. 2 ) , p .times. .times. 3 0 - p .times. .times. 0
0 + q .times. .times. 0 0 - q .times. .times. 3 0 < ( .beta. 3 )
.times. .times. and .times. .times. p .times. .times. 0 0 - q
.times. .times. 0 0 < ( 5 * t C + 1 ) 1 .times. .times. 2 )
.times. .times. 2 * ( dp .times. .times. 3 + dq .times. .times. 3 )
< ( .beta. 2 ) , p .times. .times. 3 3 - p .times. .times. 0 3 +
q .times. .times. 0 3 - q .times. .times. 3 3 < ( .beta. 3 )
.times. .times. and .times. .times. p .times. .times. 0 3 - q
.times. .times. 0 3 < ( 5 * t C + 1 ) 1 ##EQU00003##
[0061] As a same fashion, if following two conditions are met,
strong filter is used for filtering of the second 4 lines.
Otherwise, weak filter is used for filtering.
1 ) .times. .times. 2 * ( dp .times. .times. 4 + dq .times. .times.
4 ) < ( .beta. 2 ) , p .times. .times. 3 4 - p .times. .times. 0
4 + q .times. .times. 0 4 - q .times. .times. 3 4 < ( .beta. 3 )
.times. .times. and .times. .times. p .times. .times. 0 4 - q
.times. .times. 0 4 < ( 5 * t C + 1 ) 1 .times. .times. 2 )
.times. .times. 2 * ( dp .times. .times. 7 + dq .times. .times. 7 )
< ( .beta. 2 ) , p .times. .times. 3 7 - p .times. .times. 0 7 +
q .times. .times. 0 7 - q .times. .times. 3 7 < ( .beta. 3 )
.times. .times. and .times. .times. p .times. .times. 0 7 - q
.times. .times. 0 7 < ( 5 * t C + 1 ) 1 ##EQU00004##
2.1.4.1. Strong Filtering
[0062] For strong filtering, filtered pixel values are obtained by
following equations. It is worth to note that three pixels are
modified using four pixels as an input for each P and Q block,
respectively.
p 0 ` = ( p 2 + 2 * p 1 + 2 * p 0 + 2 * q 0 + q 1 + 4 ) 3 .times.
.times. q 0 ` = ( p 1 + 2 * p 0 + 2 * q 0 + 2 * q 1 + q 2 + 4 ) 3
.times. .times. p 1 ` = ( p 2 + p 1 + p 0 + q 0 + 2 ) 2 .times.
.times. q 1 ` = ( p 0 + q 0 + q 1 + q 2 + 2 ) 2 .times. .times. p 2
` = ( 2 * p 3 + 3 * p 2 + p 1 + p 0 + q 0 + 4 ) 3 .times. .times. q
2 ` = ( p 0 + q 0 + q 1 + 3 * q 2 + 2 * q 3 + 4 ) 3
##EQU00005##
2.1.4.2. Weak Filtering
[0063] Let's define .DELTA. as follows.
.DELTA. = ( 9 * ( q 0 - p 0 ) - 3 * ( q 1 - p 1 ) + 8 ) 4
##EQU00006##
When abs (.DELTA.) is less than t.sub.C*10,
.DELTA. = Clip .times. .times. 3 .times. ( - t C , t C , .DELTA. )
.times. .times. p 0 ` = Clip .times. .times. 1 Y .times. ( p 0 +
.DELTA. ) .times. .times. q 0 ` = Clip .times. .times. 1 Y .times.
( q 0 - .DELTA. ) ##EQU00007##
If dEp1 is equal to 1,
.DELTA. .times. .times. p = Clip .times. .times. 3 .times. ( - ( t
C 1 ) , t C 1 , ( ( ( p 2 + p 0 + 1 ) 1 ) - p 1 + .DELTA. ) 1 )
.times. .times. p 1 ` = Clip .times. .times. 1 Y .times. ( p 1 +
.DELTA. .times. p ) ##EQU00008##
If dEq1 is equal to 1,
.DELTA. .times. .times. q = Clip .times. .times. 3 .times. ( - ( t
C 1 ) , t C 1 , ( ( ( q 2 + q 0 + 1 ) 1 ) - q 1 - .DELTA. ) 1 )
.times. .times. q 1 ` = Clip .times. .times. 1 Y .times. ( q 1 +
.DELTA. .times. q ) ##EQU00009##
[0064] It is worth to note that maximum two pixels are modified
using three pixels as an input for each P and Q block,
respectively.
2.1.4.3. Chroma Filtering
[0065] Bs of chroma filtering is inherited from luma. If Bs>1 or
if coded chroma coefficient existing case, chroma filtering is
performed. No other filtering decision is there. And only one
filter is applied for chroma. No filter selection process for
chroma is used. The filtered sample values p.sub.0' and q.sub.0'
are derived as follows.
.DELTA. = Clip .times. .times. 3 .times. ( - t C , t C , ( ( ( ( q
0 - p 0 ) 2 ) + p 1 - q 1 + 4 ) 3 ) ) .times. .times. p 0 ` = Clip
.times. .times. 1 C .times. ( p 0 + .DELTA. ) .times. .times. q 0 `
= Clip .times. .times. 1 C .times. ( q 0 - .DELTA. )
##EQU00010##
2.2 Deblocking Scheme in VVC
[0066] In the VTM6, deblocking filtering process is mostly the same
to those in HEVC. However, the following modifications are
added.
[0067] A) The filter strength of the deblocking filter dependent of
the averaged luma level of the reconstructed samples.
[0068] B) Deblocking t.sub.C table extension and adaptation to
10-bit video.
[0069] C) 4.times.4 grid deblocking for luma.
[0070] D) Stronger deblocking filter for luma.
[0071] E) Stronger deblocking filter for chroma.
[0072] F) Deblocking filter for subblock boundary.
[0073] G) Deblocking decision adapted to smaller difference in
motion.
[0074] FIG. 5 depicts a flowchart of deblocking filters process in
VVC for a coding unit.
2.2.1. Filter Strength Dependent on Reconstructed Average Luma
[0075] In HEVC, the filter strength of the deblocking filter is
controlled by the variables .beta. and t.sub.C which are derived
from the averaged quantization parameters qP.sub.L. In the VTM6,
deblocking filter controls the strength of the deblocking filter by
adding offset to qP.sub.L according to the luma level of the
reconstructed samples if the SPS flag of this method is true. The
reconstructed luma level LL is derived as follow:
L .times. L = ( ( p 0 , 0 + p 0 , 3 + q 0 , 0 + q 0 , 3 ) 2 ) / ( 1
bitDepth ) ( 3 .times. - .times. 1 ) ##EQU00011##
where, the sample values p.sub.i,k and q.sub.i,k with i=0 . . . 3
and k=0 and 3 can be derived. Then LL is used to decide the offset
qpOffset based on the threshold signaled in SPS. After that, the
qP.sub.L, which is derived as follows, is employed to derive the
.beta. and t.sub.C
q .times. P L = ( ( Qp Q + Qp P + 1 ) 1 ) + qpOffset ( 3 .times. -
.times. 2 ) ##EQU00012##
where Qp.sub.Q and Qp.sub.P denote the quantization parameters of
the coding units containing the sample q.sub.0,0 and p.sub.0,0,
respectively. In the current VVC, this method is only applied on
the luma deblocking process.
2.2.2. 4.times.4 Deblocking Grid for Luma
[0076] HEVC uses an 8.times.8 deblocking grid for both luma and
chroma. In VTM6, deblocking on a 4.times.4 grid for luma boundaries
was introduced to handle blocking artifacts from rectangular
transform shapes. Parallel friendly luma deblocking on a 4.times.4
grid is achieved by restricting the number of samples to be
deblocked to 1 sample on each side of a vertical luma boundary
where one side has a width of 4 or less or to 1 sample on each side
of a horizontal luma boundary where one side has a height of 4 or
less.
2.2.3. Boundary Strength Derivation for Luma
[0077] The detailed boundary strength derivation could be found in
Table 2. The conditions in Table 2 are checked sequentially.
TABLE-US-00002 TABLE 2 Boundary strength derivation Conditions Y U
V P and Q are BDPCM 0 N/A N/A P or Q is intra 2 2 2 It is a
transform block edge, and P or Q is CIIP 2 2 2 It is a transform
block edge, and P or Q has non- 1 1 1 zero transform coefficients
It is a transform block edge, and P or Q is JCCR N/A 1 1 P and Q
are in different coding modes 1 1 1 One or more of the following
conditions are true: 1 N/A N/A 1. P and Q are both IBC, and the BV
distance >= half-pel in x- or y-di 2. P and Q have different ref
pictures*, or have different number of MVs 3. Both P and Q have
only one my, and the MV distance >= half-pel in x- or y-dir 4. P
has two MVs pointing to two different ref pictures, and P and Q
have same ref pictures in the list 0 , the MV pair in the list 0 or
list 1 has a distance >= half-pel in x- or y-dir 5. P has two
MVs pointing to two different ref pictures, and P and Q have
different ref pictures in the list 0, the MV of P in the list 0 and
the MV of Q in the list 1 have the distance >= half-pel in x- or
y-dir, or the MV of Pin the list 1 and the MV of Q in the list 0
have the distance >= half-pel in x- or y-dir 6. Both P and Q
have two MVs pointing to the same ref pictures, and both of the
following two conditions are satisfied: The MV of P in the list 0
and the MV of Q in the list 0 has a distance >= half-pel in x-
or y-dir or the MV of P in the list 1 and the MV of Q in the list 1
has a distance >= half-pel in x- or y-dir The MV of P in the
list 0 and the MV of Q in the list 1 has a distance >= half-pel
in x- or y-dir or the MV of P in the list 1 and the MV of Q in the
list 0 has a distance >= half-pel in x- or y-dir *Note: The
determination of whether the reference pictures used for the two
coding sublocks are the same or different is based only on
whichpictures are referenced, without regard to whether a
prediction is formed using an index into reference picture list 0
or an index into reference picture list 1, and also without regard
to whether the index position within a reference picture list is
different. Otherwise 0 0 0
2.2.4. Stronger Deblocking Filter for Luma
[0078] The proposal uses a bilinear filter when samples at either
one side of a boundary belong to a large block. A sample belonging
to a large block is defined as when the width>=32 for a vertical
edge, and when height>=32 for a horizontal edge.
[0079] The bilinear filter is listed below.
[0080] Block boundary samples pi for i=0 to Sp-1 and qi for j=0 to
Sq-1 (pi and qi follow the definitions in HEVC deblocking described
above) are then replaced by linear interpolation as follows:
p i ` = ( f i * Middl .times. e s , t + ( 6 .times. 4 - f i ) * P s
+ 32 ) 6 ) , clipped .times. .times. to .times. .times. p i .+-. t
.times. c .times. P .times. D i .times. .times. q j ` = ( g j *
Middl .times. e s , t + ( 6 .times. 4 - g j ) * Q s + 32 ) 6 ) ,
clipped .times. .times. to .times. .times. q j .+-. t .times. c
.times. P .times. D j ##EQU00013##
where tcPD.sub.i and tcPD.sub.j term is a position dependent
clipping described in Section 2.2.5 and g.sub.j, f.sub.i,
Middle.sub.s,t, P.sub.s and Q.sub.s are given below:
TABLE-US-00003 Sp, Sq f.sub.i = 59 - i * 9, can also be described
as f = {59,50,41,32,23,14,5} 7, 7 g.sub.j = 59 - j *9, can also be
described as g = {59,50,41,32,23,14,5} (p side: 7, Middle.sub.7, 7
= (2 * (p.sub.0 + g.sub.0) + p.sub.1 + q.sub.1 + p.sub.2 + q.sub.2
+ p.sub.3 + q.sub.3 + p.sub.4 + q.sub.4 + p.sub.5 + q.sub.5 +
p.sub.6 + q.sub.6 + 8) >> 4 q side: 7) P.sub.7 = (p.sub.6 +
p.sub.7 + 1) >> 1, Q.sub.7 = (q.sub.6 + q.sub.7 + 1) >>
1 7, 3 f.sub.i = 59 - i * 9, can also be described as f =
{59,50,41,32,23,14,5} (p side: 7 g.sub.j = 53 - j * 21, can also be
described as g = {53,32,11} q side: 3) Middle.sub.7, 3 = (2 *
(p.sub.0 + q.sub.0) + q.sub.0 + 2 * (q.sub.1 + q.sub.2) + p.sub.1 +
q.sub.1 + p.sub.2 + p.sub.3 + p.sub.4 + p.sub.5 + p.sub.6 + 8)
>> 4 P.sub.7 = (p.sub.6 + p.sub.7 + 1) >> 1, Q.sub.3 =
(q.sub.2 + q.sub.3 + 1) >> 1 3, 7 g.sub.j = 59 - j * 9, can
also be described as g = {59,50,41,32,23,14,5} (p side: 3 f.sub.i =
53 - i * 21, can also be described as f={53,32,11} q side: 7)
Middle.sub.3. 7 = (2 * (q.sub.0 + p.sub.0) + p.sub.0 + 2 * (p.sub.1
+ p.sub.2) + q.sub.1 + p.sub.1 + q.sub.2 + q.sub.3 + q.sub.4 +
q.sub.5 + q.sub.6 + 8) >> 4 Q.sub.7 = (q.sub.6 + q.sub.7 + 1)
>> 1, P.sub.3 = (p.sub.2 + p.sub.3 + 1) >> 1 7, 5
g.sub.j = 58 - j * 13, can also be described as g = {58,45,32,19,6}
(p side: 7 f.sub.i = 59 - i * 9, can also be described as f =
{59,50,41,32,23,14,5} q side: 5) Middle7, 5 = (2* (p.sub.0 +
q.sub.0 + p.sub.1 + q.sub.1) + q.sub.2 + p.sub.2 + q.sub.3 +
p.sub.3 + q.sub.4 + p.sub.4 + q.sub.5 + p.sub.5 + 8) >> 4
Q.sub.5 = (q.sub.4 + q.sub.5 + 1) >> 1, P.sub.7 = (p.sub.6 +
p.sub.7 + 1) >> 1 5, 7 g.sub.j = 59 - j * 9, can also be
described as g = {59,50,41,32,23,14,5} (p side: 5 f.sub.i = 58 - i
* 13, can also be described as f = {58,45,32,19,6} q side: 7)
Middle5, 7 = (2* (q.sub.0 + p.sub.0 + p.sub.1 + q.sub.1) + g.sub.2
+ p.sub.2 + q.sub.3 + p.sub.3 + q.sub.4 + p.sub.4 + q.sub.5 +
p.sub.5 + 8) >> 4 Q.sub.7 = (q.sub.6 + q.sub.7 + 1) >>
1, P.sub.5 = (p.sub.4 + p.sub.5 + 1) >> 1 5, 5 g.sub.j = 58 -
j * 13, can also be described as g = {58,45,32,19,6} (p side: 5
f.sub.i = 58 - i * 13, can also be described as f = {58,45,32,19,6}
q side: 5) Middle5, 5 = (2 * (q.sub.0 + p.sub.0 + p.sub.1 + q.sub.1
+ q.sub.2 + p.sub.2) + q.sub.3 + p.sub.3 + q.sub.4 + p.sub.4 + 8)
>> 4 Q.sub.5 = (q.sub.4 + q.sub.5 + 1) >> 1, P.sub.5 =
(p.sub.4 + p.sub.5 + 1) >> 1 5, 3 g.sub.j = 53 - j * 21, can
also be described as g = {53,32,11} (p side: 5 f.sub.i = 58 - i *
13, can also be described as f = {58,45,32,19,6} q side: 3)
Middle5, 3 = (q.sub.0 + p.sub.0 + p.sub.1 + q.sub.1 + q.sub.2 +
p.sub.2 + q.sub.3 + p.sub.3 + 4) >> 3 Q.sub.3 = (q.sub.2 +
q.sub.3 + 1) >> 1, P.sub.5 = (p.sub.4 + p.sub.5 + 1) >>
1 3, 5 g.sub.j = 58 - j * 13, can also be described as g =
{58,45,32,19,6} (p side: 3 f.sub.i = 53 - i *21, can also be
described as f = {53,32,11} q side: 5) Middle3, 5 = (q.sub.0 +
p.sub.0 + p.sub.1 + q.sub.1 + q.sub.2 + p.sub.2 + q.sub.3 + p.sub.3
+ 4) >> 3 Q.sub.5 = (q.sub.4 + q.sub.5 + 1) >> 1,
P.sub.3 = (p.sub.2 + p.sub.3 + 1) >> 1
2.2.5. Deblocking CONTROL for luma
[0081] The deblocking decision process is described in this
sub-section.
[0082] Wider-stronger luma filter is filters are used only if all
of the Condition 1, Condition 2 and Condition 3 are TRUE.
[0083] The condition 1 is the "large block condition". This
condition detects whether the samples at P-side and Q-side belong
to large blocks, which are represented by the variable
bSidePisLargeBlk and bSideQisLargeBlk respectively. The
bSidePisLargeBlk and bSideQisLargeBlk are defined as follows.
TABLE-US-00004 bSidePisLargeBlk = ((edge type is vertical and
p.sub.0 belongs to CU with width >= 32) .parallel. (edge type is
horizontal and p.sub.0 belongs to CU with height >= 32))? TRUE:
FALSE bSideQisLargeBlk = ((edge type is vertical and q.sub.0
belongs to CU with width >= 32) .parallel. (edge type is
horizontal and q.sub.0 belongs to CU with height >= 32))? TRUE:
FALSE
[0084] Based on bSidePisLargeBlk and bSideQisLargeBlk, the
condition 1 is defined as follows.
Condition .times. .times. 1 = ( bSidePisLargeBlk .times.
bSidePisLargeBlk ) ? TRUE:FALSE ##EQU00014##
[0085] Next, if Condition 1 is true, the condition 2 will be
further checked. First, the following variables are derived:
dp0, dp3, dq0, dq3 are first derived as in HEVC if (p side is
greater than or equal to 32)
d .times. p .times. 0 = ( d .times. .times. p .times. .times. 0 +
Abs .function. ( p 5 , 0 - 2 * .times. p 4 , 0 + p 3 , 0 ) + 1 ) 1
##EQU00015## d .times. .times. p .times. .times. 3 = ( d .times.
.times. p .times. .times. 3 + Abs .function. ( p 5 , 3 - 2 *
.times. p 4 , 3 + p 3 , 3 ) + 1 ) 1 ##EQU00015.2##
if (q side is greater than or equal to 32)
d .times. q .times. 0 = ( d .times. .times. q .times. .times. 0 +
Abs .function. ( q 5 , 0 - 2 * .times. q 4 , 0 + q 3 , 0 ) + 1 ) 1
##EQU00016## d .times. .times. q .times. .times. 3 = ( d .times.
.times. q .times. .times. 3 + Abs .function. ( q 5 , 3 - 2 *
.times. q 4 , 3 + q 3 , 3 ) + 1 ) 1 ##EQU00016.2##
dpq0, dpq3, dp, dq, d are then derived as in HEVC.
[0086] Then the condition 2 is defined as follows.
Condition .times. .times. 2 = ( d < .beta. ) ? TRUE:FALSE
##EQU00017##
Where d=dp0+dq0+dp3+dq3, as shown in section 2.1.4.
[0087] If Condition 1 and Condition 2 are valid it is checked if
any of the blocks uses sub-blocks:
TABLE-US-00005 If(bSidePisLargeBlk) If(mode block P ==
SUBBLOCKMODE) Sp =5 else Sp =7 else Sp = 3 If(bSideQisLargeBlk)
If(mode block Q == SUBBLOCKMODE) Sq =5 else Sq =7 else Sq = 3
[0088] Finally, if both the Condition 1 and Condition 2 are valid,
the proposed deblocking method will check the condition 3 (the
large block Strong filter condition), which is defined as follows.
In the Condition 3 StrongFilterCondition, the following variables
are derived:
TABLE-US-00006 dpq is derived as in HEVC. sp3 = Abs(p3 - p0 ),
derived as in HEVC if (p side is greater than or equal to 32)
if(Sp==5) sp3 = ( sp3 + Abs( p5 - p3 ) + 1) >> 1 else sp3 = (
sp3 + Abs( p7 - p3 ) + 1) >> 1 sq3 = Abs( q0 - q3 ), derived
as in HEVC if (q side is greater than or equal to 32) If(Sq==5) sq3
= ( sq3 + Abs( q5 - q3 ) + 1) >> 1 else sq3 = ( sq3 + Abs( q7
- q3 ) + 1) >> 1
[0089] As in HEVC derive, StrongFilterCondition=(dpq is less than
(.beta.>>2), sp3+sq3 is less than (3*.beta.>>5), and
Abs (p0-q0) is less than (5*t.sub.C+1)>>1)?TRUE:FALSE
[0090] FIG. 6 depicts the flowchart of luma deblocking filter
process.
2.2.6. Strong Deblocking Filter for Chroma
[0091] The following strong deblocking filter for chroma is
defined:
p 2 ' = ( 3 * .times. p 3 + 2 * .times. p 2 + p 1 + p 0 + q 0 + 4 )
3 ##EQU00018## p 1 ' = ( 2 * .times. p 3 + p 2 + 2 * .times. p 1 +
p 0 + q 0 + q 1 + 4 ) 3 ##EQU00018.2## p 0 ' = ( p 3 + p 2 + p 1 +
2 * .times. p 0 + q 0 + q 1 + q 2 + 4 ) 3 ##EQU00018.3##
[0092] The proposed chroma filter performs deblocking on a
4.times.4 chroma sample grid.
2.2.7. Deblocking Control for Chroma
[0093] The above chroma filter performs deblocking on a 8.times.8
chroma sample grid. The chroma strong filters are used on both
sides of the block boundary. Here, the chroma filter is selected
when both sides of the chroma edge are greater than or equal to 8
(in unit of chroma sample), and the following decision with three
conditions are satisfied. The first one is for decision of boundary
strength as well as large block. The second and third one are
basically the same as for HEVC luma decision, which are on/off
decision and strong filter decision, respectively.
[0094] FIG. 7 depicts the flowchart of chroma deblocking filter
process.
2.2.8. Position Dependent Clipping
[0095] The proposal also introduces a position dependent clipping
tcPD which is applied to the output samples of the luma filtering
process involving strong and long filters that are modifying 7, 5
and 3 samples at the boundary. Assuming quantization error
distribution, it is proposed to increase clipping value for samples
which are expected to have higher quantization noise, thus expected
to have higher deviation of the reconstructed sample value from the
true sample value.
[0096] For each P or Q boundary filtered with proposed asymmetrical
filter, depending on the result of decision making process
described in Section 2.2, position dependent threshold table is
selected from Tc7 and Tc3 tables that are provided to decoder as a
side information:
T .times. c .times. 7 = { 6 , 5 , 4 , 3 , 2 , 1 , 1 } ;
##EQU00019## T .times. .times. c .times. .times. 3 = { 6 , 4 , 2 }
; ##EQU00019.2## t .times. .times. c .times. .times. P .times.
.times. D = ( S .times. .times. P == 3 ) ? T .times. .times. c
.times. .times. 3: T .times. .times. c .times. .times. 7
##EQU00019.3## t .times. .times. c .times. .times. Q .times.
.times. D = ( S .times. .times. Q == 3 ) ? T .times. .times. c
.times. .times. 3: T .times. .times. c .times. 7 ##EQU00019.4##
[0097] For the P or Q boundaries being filtered with a short
symmetrical filter, position dependent threshold of lower magnitude
is applied:
T .times. c .times. 3 = { 3 , 2 , 1 } ; ##EQU00020##
[0098] Following defining the threshold, filtered p'i and q'i
sample values are clipped according to tcP and tcQ clipping
values:
p '' i = clip .times. .times. 3 .times. ( p ' i .times. + t .times.
.times. c .times. .times. P i , p ' i - t .times. .times. c .times.
.times. P i , p ' i ) ; ##EQU00021## q '' j = clip .times. .times.
3 .times. ( q ' j + t .times. c .times. Q j , q ' j - t .times. c
.times. Q j , q ' j ) ; ##EQU00021.2##
where p'.sub.i and q'.sub.i are filtered sample values, p'.sub.i,
and q'.sub.j are output sample value after the clipping and
tcP.sub.i tcP.sub.i are clipping thresholds that are derived from
the VVC tc parameter and tcPD and tcQD. Term clip3 is a clipping
function as it is specified in VVC.
2.2.9. Sub-Block Deblocking Adjustment
[0099] To enable parallel friendly deblocking using both long
filters and sub block deblocking the long filters is restricted to
modify at most 5 samples on a side that uses sub-block deblocking
(AFFINE or ATMVP) as shown in the luma control for long filters.
Additionally, the sub-block deblocking is adjusted such that that
sub-block boundaries on an 8.times.8 grid that are close to a CU or
an implicit TU boundary is restricted to modify at most two samples
on each side.
[0100] Following applies to sub-block boundaries that not are
aligned with the CU boundary.
TABLE-US-00007 If(mode block Q == SUBBLOCKMODE && edge!=0){
if (!(implicitTU && (edge == (64 / 4)))) if (edge == 2
.parallel. edge == (orthogonalLength - 2) .parallel. edge == (56 /
4) .parallel. edge == (72 / 4)) Sp = Sq = 2; else Sp = Sq = 3; else
Sp = Sq = bSideQisLargeBlk? 5:3 }
[0101] Where edge equal to 0 corresponds to CU boundary, edge equal
to 2 or equal to orthogonalLength-2 corresponds to sub-block
boundary 8 samples from a CU boundary etc. Where implicit TU is
true if implicit split of TU is used. FIG. 8 show the flowcharts of
determination process for TU boundaries and sub-PU boundaries.
[0102] Filtering of horizontal boundary is limiting Sp=3 for luma,
Sp=1 and Sq=1 for chroma, when the horizontal boundary is aligned
with the CTU boundary.
2.2.10. Deblocking Decision Adapted to Smaller Difference in
Motion
[0103] HEVC enables deblocking of a prediction unit boundary when
the difference in at least one motion vector component between
blocks on respective side of the boundary is equal to or larger
than a threshold of 1 sample. In VTM6, a threshold of a half luma
sample is introduced to also enable removal of blocking artifacts
originating from boundaries between inter prediction units that
have a small difference in motion vectors.
2.3. Combined Inter and Intra Prediction (CIIP)
[0104] In VTM6, when a CU is coded in merge mode, if the CU
contains at least 64 luma samples (that is, CU width times CU
height is equal to or larger than 64), and if both CU width and CU
height are less than 128 luma samples, an additional flag is
signalled to indicate if the combined inter/intra prediction (CIIP)
mode is applied to the current CU. As its name indicates, the CIIP
prediction combines an inter prediction signal with an intra
prediction signal. The inter prediction signal in the CIIP mode
P.sub.inter is derived using the same inter prediction process
applied to regular merge mode; and the intra prediction signal
P.sub.intra is derived following the regular intra prediction
process with the planar mode. Then, the intra and inter prediction
signals are combined using weighted averaging, where the weight
value is calculated depending on the coding modes of the top and
left neighbouring blocks as follows: [0105] If the top neighbor is
available and intra coded, then set isIntraTop to 1, otherwise set
isIntraTop to 0; [0106] If the left neighbor is available and intra
coded, then set isIntraLeft to 1, otherwise set isIntraLeft to 0;
[0107] If (isIntraLeft+isIntraLeft) is equal to 2, then wt is set
to 3; [0108] Otherwise, if (isIntraLeft+isIntraLeft) is equal to 1,
then wt is set to 2; [0109] Otherwise, set wt to 1.
[0110] The CIIP prediction is formed as follows:
P C .times. I .times. I .times. P = ( ( 4 - wt ) * P i .times. n
.times. t .times. e .times. r + wt * P i .times. n .times. t
.times. r .times. a + 2 ) 2 ##EQU00022##
2.4. Chroma QP Table Design in VTM-6.0
[0111] In some embodiments, a chroma QP table is used. In some
embodiments, a signalling mechanism is used for chroma QP tables,
which enables that it is flexible to provide encoders the
opportunity to optimize the table for SDR and HDR content. It
supports for signalling the tables separately for Cb and Cr
components. The proposed mechanism signals the chroma QP table as a
piece-wise linear function.
2.5. Transform Skip (TS)
[0112] As in HEVC, the residual of a block can be coded with
transform skip mode. To avoid the redundancy of syntax coding, the
transform skip flag is not signalled when the CU level MTS_CU_flag
is not equal to zero. The block size limitation for transform skip
is the same to that for MTS in JEM4, which indicate that transform
skip is applicable for a CU when both block width and height are
equal to or less than 32. Note that implicit MTS transform is set
to DCT2 when LFNST or MIP is activated for the current CU. Also the
implicit MTS can be still enabled when MTS is enabled for inter
coded blocks.
[0113] In addition, for transform skip block, minimum allowed
Quantization Parameter (QP) is defined as
6*(internalBitDepth-inputBitDepth)+4.
2.6. Joint Coding of Chroma Residuals (JCCR)
[0114] In some embodiments, the chroma residuals are coded jointly.
The usage (activation) of a joint chroma coding mode is indicated
by a TU-level flag tu_joint_cbcr_residual_flag and the selected
mode is implicitly indicated by the chroma CBFs. The flag
tu_joint_cbcr_residual_flag is present if either or both chroma
CBFs for a TU are equal to 1. In the PPS and slice header, chroma
QP offset values are signalled for the joint chroma residual coding
mode to differentiate from the usual chroma QP offset values
signalled for regular chroma residual coding mode. These chroma QP
offset values are used to derive the chroma QP values for those
blocks coded using the joint chroma residual coding mode. When a
corresponding joint chroma coding mode (modes 2 in Table 3) is
active in a TU, this chroma QP offset is added to the applied
luma-derived chroma QP during quantization and decoding of that TU.
For the other modes (modes 1 and 3 in Table 3 Table 3
Reconstruction of chroma residuals. The value CSign is a sign value
(+1 or -1), which is specified in the slice header, resJointC[][]
is the transmitted residual.), the chroma QPs are derived in the
same way as for conventional Cb or Cr blocks. The reconstruction
process of the chroma residuals (resCb and resCr) from the
transmitted transform blocks is depicted in Table 3. When this mode
is activated, one single joint chroma residual block
(resJointC[x][y] in Table 3) is signalled, and residual block for
Cb (resCb) and residual block for Cr (resCr) are derived
considering information such as tu_cbf_cb, tu_cbf_cr, and CSign,
which is a sign value specified in the slice header.
[0115] At the encoder side, the joint chroma components are derived
as explained in the following. Depending on the mode (listed in the
tables above), resJointC{1,2} are generated by the encoder as
follows: [0116] If mode is equal to 2 (single residual with
reconstruction Cb=C, Cr=CSign*C), the joint residual is determined
according to
[0116] resJointC .function. [ x ] .function. [ y ] = ( resCb
.function. [ x ] .function. [ y ] + C .times. Sign * .times. resCr
.function. [ x ] .function. [ y ] ) / 2. ##EQU00023## [0117]
Otherwise, if mode is equal to 1 (single residual with
reconstruction Cb=C, Cr=(CSign*C)/2), the joint residual is
determined according to
[0117] resJointC .function. [ x ] .function. [ y ] = ( 4 * .times.
resCb .function. [ x ] .function. [ y ] + 2 * .times. C .times.
Sign * .times. resCr .function. [ x ] .function. [ y ] ) / 5.
##EQU00024## [0118] Otherwise (mode is equal to 3, i. e., single
residual, reconstruction Cr=C, Cb=(CSign*C)/2), the joint residual
is determined according to
[0118] resJointC .function. [ x ] .function. [ y ] = ( 4 * .times.
r .times. e .times. s .times. C .times. r .function. [ x ]
.function. [ y ] + 2 * .times. C .times. Sign * .times. resCb
.function. [ x ] .function. [ y ] ) / 5. ##EQU00025##
TABLE-US-00008 TABLE 3 Reconstruction of chroma residuals. The
value CSign is a sign value (+1 or -1), which is specified in the
slice header, resJointC[ ][ ] is the transmitted residual.
tu_cbf_cb tu_cbf_cr reconstruction of Cb and Cr residuals mode 1 0
resCb[ x ][ y ] = resJointC[ x ][ y ] 1 resCr[ x ][ y ] = ( CSign *
resJointC[ x ][ y ] ) >> 1 1 1 resCb[ x ][ y ] = resJointC[ x
][ y ] 2 resCr[ x ][ y ] = CSign * resJointC[ x ][ y ] 0 1 resCb[ x
][ y ] = ( CSign * resJointC[ x ][ y ] ) >> 1 3 resCr[ x ][ y
] = resJointC[ x ][ y ]
[0119] Different QPs are utilized are the above three modes. For
mode 2, the QP offset signaled in PPS for JCCR coded block is
applied, while for other two modes, it is not applied, instead, the
QP offset signaled in PPS for non-JCCR coded block is applied.
[0120] The corresponding specification is as follows:
8.7.1 Derivation process for quantization parameters The variable
Qp.sub.Y is derived as follows:
Qp Y = ( ( qP Y .times. _ .times. PRED + CuQpDeltaVal + 64 + 2 *
.times. QpBdOffset Y ) .times. % .times. ( 6 .times. 4 + QpBdOffset
Y ) ) - QpBdOffset Y (8-933) ##EQU00026##
The luma quantization parameter Qp'.sub.Y is derived as
follows:
Qp ' Y = Qp Y + QpBdOffset Y (8-934) ##EQU00027##
When ChromaArrayType is not equal to 0 and treeType is equal to
SINGLE_TREE or DUAL_TREE_CHROMA, the following applies: [0121] When
treeType is equal to DUAL_TREE_CHROMA, the variable Qp.sub.Y is set
equal to the luma quantization parameter Qp.sub.Y of the luma
coding unit that covers the luma location
(xCb+cbWidth/2,yCb+cbHeight/2). [0122] The variables qP.sub.Cb,
qP.sub.Cr and qP.sub.CbCr are derived as follows:
[0122] q .times. P .times. i C .times. h .times. r .times. o
.times. m .times. a = Clip .times. .times. 3 .times. ( - Q .times.
.times. p .times. .times. B .times. .times. d .times. .times.
Offset C , 63 , Q .times. .times. p Y ) (8-935) q .times. .times. P
.times. .times. i C .times. b = ChromaQpTable .function. [ 0 ]
.function. [ q .times. .times. P .times. .times. i Chroma ] (8-936)
q .times. .times. P .times. .times. i C .times. r = ChromaQpTable
.function. [ 1 ] .function. [ q .times. .times. P .times. .times. i
Chroma ] (8-937) q .times. .times. P .times. .times. i C .times. b
.times. C .times. r = ChromaQpTable .function. [ 2 ] .function. [ q
.times. .times. P .times. .times. i Chroma ] (8-938) ##EQU00028##
[0123] The chroma quantization parameters for the Cb and Cr
components, Qp'.sub.Cb and Qp'.sub.Cr, and joint Cb-Cr coding
Qp'.sub.CbCr are derived a s follows:
[0123] Qp ' Cb = Clip .times. .times. 3 .times. ( - QpBDOffset C ,
63 , qP Cb + pps_cb .times. _qp .times. _offset + slice_cb .times.
_qp .times. _offset + CuQpOffset Cb ) + QpBdOffset C (8-939) Qp '
Cr = Clip .times. .times. 3 .times. ( - QpBDOffset C , 63 , qP Cr +
pps_cr .times. _qp .times. _offset + slice_cr .times. _qp .times.
_offset + CuQpOffset Cr ) + QpBdOffset C (8-940) Qp ' CbCr = Clip
.times. .times. 3 .times. ( - QpBDOffset C , 63 , qP CbCr +
pps_cbcr .times. _qp .times. _offset + slice_cbcr .times. _qp
.times. _offset + CuQpOffset CbCr ) + QpBdOffset C (8-941)
##EQU00029##
8.7.3 Scaling Process for Transform Coefficients
[0124] Inputs to this process are: [0125] a luma location
(xTbY,yTbY) specifying the top-left sample of the current luma
transform block relative to the top-left luma sample of the current
picture, [0126] a variable nTbW specifying the transform block
width, [0127] a variable nTbH specifying the transform block
height, [0128] a variable cIdx specifying the colour component of
the current block, [0129] a variable bitDepth specifying the bit
depth of the current colour component. Output of this process is
the (nTbW).times.(nTbH) array d of scaled transform coefficients
with elements d[x][y]. The quantization parameter qP is derived as
follows: [0130] If cIdx is equal to 0 and transform skip
flag[xTbY][yTbY] is equal to 0, the following applies:
[0130] qP = Qp ' Y (8-950) ##EQU00030## [0131] Otherwise, if cIdx
is equal to 0 (and transform_skip_flag[xTbY][yTbY] is equal to 1),
the following applies:
[0131] q .times. P = Max .function. ( QpPrimeTs .times. Min , Qp '
Y ) (8-951) ##EQU00031## [0132] Otherwise, if
TuCResMode[xTbY][yTbY] is equal to 2, the following applies:
[0132] qP = Qp ' CbCr (8-952) ##EQU00032## [0133] Otherwise, if
cIdx is equal to 1, the following applies:
[0133] qP = Qp ' Cb (8-953) ##EQU00033## [0134] Otherwise (cIdx is
equal to 2), the following applies:
[0134] qP = Qp ' Cr (8-954) ##EQU00034##
2.7. Cross-Component Adaptive Loop Filter (CC-ALF)
[0135] FIG. 14A illustrates the placement of CC-ALF with respect to
the other loop filters. CC-ALF operates by applying a linear,
diamond shaped filter (FIG. 14B) to the luma channel for each
chroma component, which is expressed as
where
.DELTA. .times. .times. I i .function. ( x , y ) = ( x 0 , y 0 )
.di-elect cons. S i .times. I 0 .function. ( x c + x 0 , y c + y 0
) .times. c i .function. ( x 0 , y 0 ) , ##EQU00035## [0136] (x,y)
is chroma component i location being refined [0137]
(x.sub.C,y.sub.C) is the luma location based on (x,y) [0138]
S.sub.i is filter support in luma for chroma component i [0139]
c.sub.i(x.sub.0,y.sub.0) represents the filter coefficients
[0140] Key features characteristics of the CC-ALF process
include:
[0141] The luma location (x.sub.C,y.sub.C), around which the
support region is centered, is computed based on the spatial
scaling factor between the luma and chroma planes.
[0142] All filter coefficients are transmitted in the APS and have
8-bit dynamic range.
[0143] An APS may be referenced in the slice header.
[0144] CC-ALF coefficients used for each chroma component of a
slice are also stored in a buffer corresponding to a temporal
sublayer. Reuse of these sets of temporal sublayer filter
coefficients is facilitated using slice-level flags.
[0145] The application of the CC-ALF filters is controlled on a
variable block size and signalled by a context-coded flag received
for each block of samples. The block size along with an CC-ALF
enabling flag is received at the slice-level for each chroma
component.
[0146] Boundary padding for the horizontal virtual boundaries makes
use of repetition. For the remaining boundaries the same type of
padding is used as for regular ALF.
3. Drawbacks of Existing Implementations
[0147] DMVR and BIO do not involve the original signal during
refining the motion vectors, which may result in coding blocks with
inaccurate motion information. Also, DMVR and BIO sometimes employ
the fractional motion vectors after the motion refinements while
screen videos usually have integer motion vectors, which makes the
current motion information more inaccurate and make the coding
performance worse. [0148] 1. The interaction between chroma QP
table and chroma deblocking may have problems, e.g. chroma QP table
should be applied to individual QP but not weighted sum of QPs.
[0149] 2. The logic of luma deblocking filtering process is
complicated for hardware design. [0150] 3. The logic of boundary
strength derivation is too complicated for both software and
hardware design. [0151] 4. In the BS decision process, JCCR is
treated separately from those blocks coded without JCCT applied.
However, JCCR is only a special way to code the residual.
Therefore, such design may bring additional complexity without no
clear benefits. [0152] 5. In chroma edge decision, Qp.sub.Q and
Qp.sub.P are set equal to the Qp.sub.Y values of the coding units
which include the coding blocks containing the sample q.sub.0,0 and
p.sub.0,0 , respectively. However, in the
quantization/de-quantization process, the QP for a chroma sample is
derived from the QP of luma block covering the corresponding luma
sample of the center position of current chroma CU. When dual tree
is enabled, the different locations of luma blocks may result in
different QPs. Therefore, in the chroma deblocking process, wrong
QPs may be used for filter decision. Such a misalignment may result
in visual artifacts. An example is shown in FIGS. 9A-B. FIG. 9A
shows the corresponding CTB partitioning for luma block and FIG. 9B
shows the chroma CTB partitioning under dual tree. When determining
the QP for chroma block, denoted by CU.sub.c1, the center position
of CU.sub.c1 is firstly derived. Then the corresponding luma sample
of the center position of CU.sub.c1 is identified and luma QP
associated with the luma CU that covers the corresponding luma
sample, i.e., CU.sub.Y3 is then untilized to derive the QP for
CU.sub.C1. However, when making filter decisions for the depicted
three samples (with solid circles), the QPs of CUs that cover the
corresponding 3 samples are selected. Therefore, for the 1.sup.st,
2.sup.nd, and 3.sup.rd chroma sample (depicted in FIG. 9B), the QPs
of CU.sub.Y2, CU.sub.Y3, CU.sub.Y4 are utilized, respectively. That
is, chroma samples in the same CU may use different QPs for filter
decision which may result in wrong decisions. [0153] 6. A different
picture level QP offset (i.e., pps_joint_cbcr_qp_offset) is applied
to JCCR coded blocks which is different from the picture level
offsets for Cb/Cr (e.g., pps_cb_qp_offset and pps_cr_qp_offset)
applied to non-JCCR coded blocks. However, in the chroma deblocking
filter decision process, only those offsets for non-JCCR coded
blocks are utilized. The missing of consideration of coded modes
may result in wrong filter decision. [0154] 7. The TS and non-TS
coded blocks employ different QPs in the de-quantization process,
which may be also considered in the deblocking process. [0155] 8.
Different QPs are used in the scaling process
(quantization/dequantization) for JCCR coded blocks with different
modes. Such a design is not consistent. [0156] 9. The chroma
deblocking for Cb/Cr could be unfied for parallel design.
4. Example Techniques and Embodiments
[0157] The detailed embodiments described below should be
considered as examples to explain general concepts. These
embodiments should not be interpreted narrowly way. Furthermore,
these embodiments can be combined in any manner.
[0158] The methods described below may be also applicable to other
decoder motion information derivation technologies in addition to
the DMVR and BIO mentioned below.
[0159] In the following examples, MVM[i].x and MVM[i].y denote the
horizontal and vertical component of the motion vector in reference
picture list i (i being 0 or 1) of the block at M (M being P or Q)
side. Abs denotes the operation to get the absolute value of an
input, and "&&" and ".parallel." denotes the logical
operation AND and OR. Referring to FIG. 10, P may denote the
samples at P side and Q may denote the samples at Q side. The
blocks at P side and Q side may denote the block marked by the dash
lines.
Regarding Chroma QP in Deblocking
[0160] 1. When chroma QP table is used to derive parameters to
control chroma deblocking (e.g., in the decision process for chroma
block edges), chroma QP offsets may be applied after applying
chroma QP table. [0161] a. In one example, the chroma QP offsets
may be added to the value outputted by a chroma QP table. [0162] b.
Alternatively, the chroma QP offsets may be not considered as input
to a chroma QP table. [0163] c. In one example, the chroma QP
offsets may be the picture-level or other video unit-level
(slice/tile/brick/subpicture) chroma quantization parameter offset
(e.g., pps_cb_qp_offset, pps_cr_qp_offset in the specification).
[0164] 2. QP clipping may be not applied to the input of a chroma
QP table. [0165] 3. It is proposed that deblocking process for
chroma components may be based on the mapped chroma QP (by the
chroma QP table) on each side. [0166] a. In one example, it is
proposed that deblocking parameters, (e.g., .beta. and tC) for
chroma may be based on QP derived from luma QP on each side. [0167]
b. In one example, the chroma deblocking parameter may depend on
chroma QP table value with QpP as the table index, where QpP, is
the luma QP value on P-side. [0168] c. In one example, the chroma
deblocking parameter may depend on chroma QP table value with QpQ
as the table index, where QpQ, is the luma QP value on Q-side.
[0169] 4. It is proposed that deblocking process for chroma
components may be based on the QP applied to
quantization/dequantization for the chroma block. [0170] a. In one
example, QP for deblocking process may be equal to the QP in
dequantization. [0171] 5. It is proposed to consider the
picture/slice/tile/brick/subpicture level quantization parameter
offsets used for different coding methods in the deblocking filter
decision process. [0172] a. In one example, selection of
picture/slice/tile/brick/subpicture level quantization parameter
offsets for filter decision (e.g., the chroma edge decision in the
deblocking filter process) may depend on the coded methods for each
side. [0173] b. In one example, the filtering process (e.g., the
chroma edge decision process) which requires to use the
quantization parameters for chroma blocks may depend on whether the
blocks use JCCR. [0174] i. Alternatively, furthermore, the
picture/slice-level QP offsets (e.g., pps_joint_cbcr_qp_offset)
applied to JCCR coded blocks may be further taken into
consideration in the deblocking filtering process. [0175] ii. In
one example, the cQpPicOffset which is used to decide Tc and .beta.
settings may be set to pps_joint_cbcr_qp_offset instead of
pps_cb_qp_offset or pps_cr_qp_offset under certain conditions:
[0176] 1. In one example, when either block in P or Q sides uses
JCCR. [0177] 2. In one example, when both blocks in P or Q sides
uses JCCR. [0178] iii. Alternatively, furthermore, the filtering
process may depend on the mode of JCCR (e.g., whether mode is equal
to 2). [0179] 6. The chroma filtering process (e.g., the chroma
edge decision process) which requires to access the decoded
information of a luma block may utilize the information associated
with the same luma coding block that is used to derive the chroma
QP in the dequantization/quantization process. [0180] a. In one
example, the chroma filtering process (e.g., the chroma edge
decision process) which requires to use the quantization parameters
for luma blocks may utilize the luma coding unit covering the
corresponding luma sample of the center position of current chroma
CU. [0181] b. An example is depicted in FIGS. 9A-B wherein the
decoded information of CU.sub.Y3 may be used for filtering decision
of the three chroma samples (1.sup.st, 2.sup.nd and 3.sup.rd) in
FIG. 9B. [0182] 7. The chroma filtering process (e.g., the chroma
edge decision process) may depend on the quantization parameter
applied to the scaling process of the chroma block (e.g.,
quantization/dequantization). [0183] a. In one example, the QP used
to derive .beta. and Tc may depend on the QP applied to the scaling
process of the chroma block. [0184] b. Alternatively, furthermore,
the QP used to the scaling process of the chroma block may have
taken the chroma CU level QP offset into consideration. [0185] 8.
Whether to invoke above bullets may depend on the sample to be
filtered is in the block at P or Q side. [0186] a. For example,
whether to use the information of the luma coding block covering
the corresponding luma sample of current chroma sample or use the
information of the luma coding block covering the corresponding
luma sample of center position of chroma coding block covering
current chroma sample may depend on the block position. [0187] i.
In one example, if the current chroma sample is in the block at the
Q side, QP information of the luma coding block covering the
corresponding luma sample of center position of chroma coding block
covering current chroma sample may be used. [0188] ii. In one
example, if the current chroma sample is in the block at the P
side, QP information of the luma coding block covering the
corresponding luma sample of the chroma sample may be used. [0189]
9. Chroma QP used in deblocking may depend on information of the
corresponding transform block. [0190] a. In one example, chroma QP
for deblocking at P-side may depend on the transform block's mode
at P-side. [0191] i. In one example, chroma QP for deblocking at
P-side may depend on if the transform block at P-side is coded with
JCCR applied. [0192] ii. In one example, chroma QP for deblocking
at P-side may depend on if the transform block at P-side is coded
with joint_cb_cr_mode and the mode of JCCR is equal to 2. [0193] b.
In one example, chroma QP for deblocking at Q-side may depend on
the transform block's mode at Q-side. [0194] i. In one example,
chroma QP for deblocking at Q-side may depend on if the transform
block at Q-side is coded with JCCR applied. [0195] ii. In one
example, chroma QP for deblocking at Q-side may depend on if the
transform block at Q-side is coded with JCCR applied and the mode
of JCCR is equal to 2. [0196] 10. Signaling of chroma QPs may be in
coding unit. [0197] a. In one example, when coding unit size is
larger than the maximum transform block size, i.e., maxTB, chroma
QP may be signaled in CU level. Alternatively, it may be signaled
in TU level. [0198] b. In one example, when coding unit size is
larger than the size of VPDU, chroma QP may be signaled in CU
level. Alternatively, it may be signaled in TU level. [0199] 11.
Whether a block is of joint_cb_cr mode may be indicated at coding
unit level. [0200] a. In one example, whether a transform block is
of joint_cb_cr mode may inherit the information of the coding unit
containing the transform block. [0201] 12. Chroma QP used in
deblocking may depend on chroma QP used in scaling process minus QP
offset due to bit depth. [0202] a. In one example, Chroma QP used
in deblocking at P-side is set to the JCCR chroma QP used in
scaling process, i.e. Qp'.sub.CbCr, minus QpBdOffsetC when
TuCResMode[xTb][yTb] is equal to 2 where (xTb,yTb) denotes the
transform blocking containing the first sample at P-side, i.e.
p.sub.0,0. [0203] b. In one example, Chroma QP used in deblocking
at P-side is set to the Cb chroma QP used in scaling process, i.e.
Qp'.sub.Cb, minus QpBdOffsetC when TuCResMode[xTb][yTb] is equal to
2 where (xTb,yTb) denotes the transform blocking containing the
first sample at P-side, i.e. p.sub.0,0. [0204] c. In one example,
Chroma QP used in deblocking at P-side is set to the Cr chroma QP
used in scaling process, i.e. Qp'.sub.Cr, minus QpBdOffsetC when
TuCResMode[xTb][yTb] is equal to 2 where (xTb,yTb) denotes the
transform blocking containing the first sample at P-side, i.e.
p.sub.0,0. [0205] d. In one example, Chroma QP used in deblocking
at Q-side is set to the JCCR chroma QP used in scaling process,
i.e. Qp'.sub.CbCr, minus QpBdOffsetC when TuCResMode[xTb][yTb] is
equal to 2 where (xTb,yTb) denotes the transform blocking
containing the last sample at Q-side, i.e. q.sub.0,0. [0206] e. In
one example, Chroma QP used in deblocking at Q-side is set to the
Cb chroma QP used in scaling process, i.e. Qp'.sub.Cb, minus
QpBdOffsetC when TuCResMode[xTb][yTb] is equal to 2 where (xTb,yTb)
denotes the transform blocking containing the last sample at
Q-side, i.e. q.sub.0,0. [0207] 13. In one example, Chroma QP used
in deblocking at Q-side is set to the Cr chroma QP used in scaling
process, i.e. Qp'.sub.Cr, minus QpBdOffsetC when
TuCResMode[xTb][yTb] is equal to 2 where (xTb,yTb) denotes the
transform blocking containing the last sample at Q-side, i.e.
q.sub.0,0
Regarding QP Settings
[0207] [0208] 14. It is proposed to signal the indication of
enabling block-level chroma QP offset (e.g.
slice_cu_chroma_qp_offset_enabled_flag) at the
slice/tile/brick/subpicture level. [0209] a. Alternatively, the
signaling of such an indication may be conditionally signaled.
[0210] i. In one example, it may be signaled under the condition of
JCCR enabling flag. [0211] ii. In one example, it may be signaled
under the condition of block-level chroma QP offset enabling flag
in picture level. [0212] iii. Alternatively, such an indication may
be derived instead. [0213] b. In one example, the
slice_cu_chroma_qp_offset_enabled_flag may be signaled only when
the PPS flag of chroma QP offset (e.g.
slice_cu_chroma_qp_offset_enabled_flag) is true. [0214] c. In one
example, the slice_cu_chroma_qp_offset_enabled_flag may be inferred
to false only when the PPS flag of chroma QP offset (e.g.
slice_cu_chroma_qp_offset_enabled_flag) is false. [0215] d. In one
example, whether to use the chroma QP offset on a block may be
based on the flags of chroma QP offset at PPS level and/or slice
level. [0216] 15. Same QP derivation method is used in the scaling
process (quantization/dequantization) for JCCR coded blocks with
different modes. [0217] a. In one example, for JCCR with mode 1 and
3, the QP is dependent on the QP offset signaled in the
picture/slice level (e.g., pps_cbcr_qp_offset,
slice_cbcr_qp_offset).
Filtering Procedures
[0217] [0218] 16. Deblocking for all color components excepts for
the first color component may follow the deblocking process for the
first color component. [0219] a. In one example, when the color
format is 4:4:4, deblocking process for the second and third
components may follow the deblocking process for the first
component. [0220] b. In one example, when the color format is 4:4:4
in RGB color space, deblocking process for the second and third
components may follow the deblocking process for the first
component. [0221] c. In one example, when the color format is
4:2:2, vertical deblocking process for the second and third
components may follow the vertical deblocking process for the first
component. [0222] d. In above examples, the deblocking process may
refer to deblocking decision process and/or deblocking filtering
process. [0223] 17. How to calculate gradient used in the
deblocking filter process may depend on the coded mode information
and/or quantization parameters. [0224] a. In one example, the
gradient computation may only consider the gradient of a side
wherein the samples at that side are not lossless coded. [0225] b.
In one example, if both sides are lossless coded or nearly lossless
coded (e.g., quantization parameters equal to 4), gradient may be
directly set to 0. [0226] i. Alternatively, if both sides are
lossless coded or nearly lossless coded (e.g., quantization
parameters equal to 4), Boundary Strength (e.g., BS) may be set to
0. [0227] c. In one example, if the samples at P side are lossless
coded and the samples at Q side are lossy coded, the gradients used
in deblocking on/off decision and/or strong filters on/off decision
may only include gradients of the samples at Q side, vice versa.
[0228] i. Alternatively, furthermore, the gradient of one side may
be scaled by N. [0229] 1. N is an integer number (e.g. 2) and may
depend on a. Video contents (e.g. screen contents or natural
contents) b. A message signaled in the DPS/SPS/VPS/PPS/APS/picture
header/slice header/tile group header/Largest coding unit
(LCU)/Coding unit (CU)/LCU row/group of LCUs/TU/PU block/Video
coding unit c. Position of CU/PU/TU/block/Video coding unit d.
Coded modes of blocks containing the samples along the edges e.
Transform matrices applied to the blocks containing the samples
along the edges f. Block dimension/Block shape of current block
and/or its neighboring blocks g. Indication of the color format
(such as 4:2:0, 4:4:4, RGB or YUV) h. Coding tree structure (such
as dual tree or single tree) i. Slice/tile group type and/or
picture type j. Color component (e.g. may be only applied on Cb or
Cr) k. Temporal layer ID l. Profiles/Levels/Tiers of a standard m.
Alternatively, N may be signalled to the decoder
Regarding Boundary Strength Derivation
[0229] [0230] 18. It is proposed to treat JCCR coded blocks as
those non-JCCR coded blocks in the boundary strength decision
process. [0231] a. In one example, the determination of boundary
strength (BS) may be independent from the checking of usage of JCCR
for two blocks at P and Q sides. [0232] b. In one example, the
boundary strength (BS) for a block may be determined regardless if
the block is coded with JCCR or not. [0233] 19. It is proposed to
derive the boundary strength (BS) without comparing the reference
pictures and/or number of MVs associated with the block at P side
with the reference pictures of the block at Q side. [0234] a. In
one example, deblocking filter may be disabled even when two blocks
are with different reference pictures. [0235] b. In one example,
deblocking filter may be disabled even when two blocks are with
different number of MVs (e.g., one is uni-predicted and the other
is bi-predicted). [0236] c. In one example, the value of BS may be
set to 1 when motion vector differences for one or all reference
picture lists between the blocks at P side and Q side is larger
than or equal to a threshold Th. [0237] i. Alternatively,
furthermore, the value of BS may be set to 0 when motion vector
differences for one or all reference picture lists between the
blocks at P side and Q side is smaller than or equal to a threshold
Th. [0238] d. In one example, the difference of the motion vectors
of two blocks being larger than a threshold Th may be defined as
(Abs(MVP[0].x-MVQ[0].x)>Th.parallel.Abs(MVP[0].y-MVQ[0].y)>Abs(MVP[-
1].x-MVQ[1].x)>Th).parallel.Abs(MVP[1].y-MVQ[1].y) >Th)
[0239] ii. Alternatively, the difference of the motion vectors of
two blocks being larger than a threshold Th may be defined as
(Abs(MVP[0].x -MVQ[0].x)>Th&&
Abs(MVP[0].y-MVQ[0].y)>Th && Abs(MVP[1].x
-MVQ[1].x)>Th)&& Abs(MVP[1].y-MVQ[1].y)>Th) [0240]
iii. Alternatively, in one example, the difference of the motion
vectors of two blocks being larger than a threshold Th may be
defined as
(Abs(MVP[0].x-MVQ[0].x)>.parallel.Abs(MVP[0].y-MVQ[0].y)>Th)&&(Abs(-
MVP[1].x-MVQ[1].x)>Th).parallel.Abs(MVP[1].y-MVQ[1].y)>Th)
[0241] iv. Alternatively, in one example, the difference of the
motion vectors of two blocks being larger than a threshold Th may
be defined as
(Abs(MVP[0].x-MVQ[0].x)>Th&&Abs(MVP[0].y-MVQ[0].y)>Th).parallel.(Ab-
s(MVP[1].x-MVQ[1].x)>Th)&&Abs(MVP[1].y-MVQ[1].y)>Th)
[0242] e. In one example, a block which does not have a motion
vector in a given list may be treated as having a zero-motion
vector in that list. [0243] f. In the above examples, Th is an
integer number (e.g. 4, 8 or 16). [0244] g. In the above examples,
Th may depend on [0245] v. Video contents (e.g. screen contents or
natural contents) [0246] vi. A message signaled in the
DPS/SPS/VPS/PPS/APS/picture header/slice header/tile group
header/Largest coding unit (LCU)/Coding unit (CU)/LCU row/group of
LCUs/TU/PU block/Video coding unit [0247] vii. Position of
CU/PU/TU/block/Video coding unit [0248] viii. Coded modes of blocks
containing the samples along the edges [0249] ix. Transform
matrices applied to the blocks containing the samples along the
edges [0250] x. Block dimension/Block shape of current block and/or
its neighboring blocks [0251] xi. Indication of the color format
(such as 4:2:0, 4:4:4, RGB or YUV) [0252] xii. Coding tree
structure (such as dual tree or single tree) [0253] xiii.
Slice/tile group type and/or picture type [0254] xiv. Color
component (e.g. may be only applied on Cb or Cr) [0255] xv.
Temporal layer ID [0256] xvi. Profiles/Levels/Tiers of a standard
[0257] xvii. Alternatively, Th may be signalled to the decoder.
[0258] h. The above examples may be applied under certain
conditions. [0259] xviii. In one example, the condition is the blkP
and blkQ are not coded with intra modes. [0260] xix. In one
example, the condition is the blkP and blkQ have zero coefficients
on luma component. [0261] xx. In one example, the condition is the
blkP and blkQ are not coded with the CIIP mode. [0262] xxi. In one
example, the condition is the blkP and blkQ are coded with a same
prediction mode (e.g. IBC or Inter).
Regarding Luma Deblocking Filtering Process
[0262] [0263] 20. The deblocking may use different QPs for TS coded
blocks and non-TS coded blocks. [0264] a. In one example, the QP
for TS may be used on TS coded blocks while the QP for non-TS may
be used on non-TS coded blocks. [0265] 21. The luma filtering
process (e.g., the luma edge decision process) may depend on the
quantization parameter applied to the scaling process of the luma
block. [0266] a. In one example, the QP used to derive beta and Tc
may depend on the clipping range of transform skip, e.g. as
indicated by QpPrimeTsMin. [0267] 22. It is proposed to use an
identical gradient computation for large block boundaries and
smaller block boundaries. [0268] a. In one example, the deblocking
filter on/off decision described in section 2.1.4 may be also
applied for large block boundary. [0269] i. In one example, the
threshold beta in the decision may be modified for large block
boundary. [0270] 1. In one example, beta may depend on quantization
parameter. [0271] 2. In one example, beta used for deblocking
filter on/off decision for large block boundaries may be smaller
than that for smaller block boundaries. a. Alternatively, in one
example, beta used for deblocking filter on/off decision for large
block boundaries may be larger than that for smaller block
boundaries. b. Alternatively, in one example, beta used for
deblocking filter on/off decision for large block boundaries may be
equal to that for smaller block boundaries. [0272] 3. In one
example, beta is an integer number and may be based on a. Video
contents (e.g. screen contents or natural contents) b. A message
signaled in the DPS/SPS/VPS/PPS/APS/picture header/slice
header/tile group header/Largest coding unit (LCU)/Coding unit
(CU)/LCU row/group of LCUs/TU/PU block/Video coding unit c.
Position of CU/PU/TU/block/Video coding unit d. Coded modes of
blocks containing the samples along the edges e. Transform matrices
applied to the blocks containing the samples along the edges f.
Block dimension of current block and/or its neighboring blocks g.
Block shape of current block and/or its neighboring blocks h.
Indication of the color format (such as 4:2:0, 4:4:4, RGB or YUV)
i. Coding tree structure (such as dual tree or single tree) j.
Slice/tile group type and/or picture type k. Color component (e.g.
may be only applied on Cb or Cr) l. Temporal layer ID m.
Profiles/Levels/Tiers of a standard n. Alternatively, beta may be
signalled to the decoder.
Regarding Scaling Matrix (Dequantization Matrix)
[0272] [0273] 23. The values for specific positions of quantization
matrices may be set to constant. [0274] a. In one example, the
position may be the position of (x,y) wherein x and y are two
integer variables (e.g., x=y=0), and (x,y) is the coordinate
relative to a TU/TB/PU/PB/CU/CB. [0275] i. In one example, the
position may be the position of DC. [0276] b. In one example, the
constant value may be 16. [0277] c. In one example, for those
positions, signaling of the matrix values may not be utilized.
[0278] 24. A constrain may be set that the average/weighted average
of some positions of quantization matrices may be a constant.
[0279] a. In one example, deblocking process may depend on the
constant value. [0280] b. In one example, the constant value may be
indicated in DPS/VPS/SPS/PPS/Slice/Picture/Tile/Brick headers.
[0281] 25. One or multiple indications may be signaled in the
picture header to inform the scaling matrix to be selected in the
picture associated with the picture header.
Regarding Cross Component Adaptive Loop Filter (CCALF)
[0281] [0282] 26. CCALF may be applied before some loop filtering
process at the decoder [0283] a. In one example, CCALF may be
applied before deblocking process at the decoder. [0284] b. In one
example, CCALF may be applied before SAO at the decoder. [0285] c.
In one example, CCALF may be applied before ALF at the decoder.
[0286] d. Alternatively, the order of different filters (e.g.,
CCALF, ALF, SAO, deblocking filter) may be NOT fixed. [0287] i. In
one example, the invoke of CCLAF may be before one filtering
process for one video unit or after another one for another video
unit. [0288] ii. In one example, the video unit may be a
CTU/CTB/slice/tile/brick/picture/sequence. [0289] e. Alternatively,
indications of the order of different filters (e.g., CCALF, ALF,
SAO, deblocking filter) may be signaled or derived on-the-fly.
[0290] i. Alternatively, indication of the invoking of CCALF may be
signaled or derived on-the-fly. [0291] f. The explicit (e.g.
signaling from the encoder to the decoder) or implicit (e.g.
derived at both encoder and decoder) indications of how to control
CCALF may be decoupled for different color components (such as Cb
and Cr). [0292] g. Whether and/or how to apply CCALF may depend on
color formats (such as RGB and YCbCr) and/or color sampling format
(such as 4:2:0, 4:2:2 and 4:4:4), and/or color down-sampling
positions or phases)
Regarding Chroma QP Offset Lists
[0292] [0293] 27. Signaling and/or selection of chroma QP offset
lists may be dependent on the coded prediction modes/picture
types/slice or tile or brick types. [0294] h. Chroma QP offset
lists, e.g. cb_qp_offset_list[i], cr_qp_offset_list[i], and
joint_cbcr_qp_offset_list[i], may be different for different coding
modes. [0295] i. In one example, whether and how to apply chroma QP
offset lists may depend on whether the current block is coded in
intra mode. [0296] j. In one example, whether and how to apply
chroma QP offset lists may depend on whether the current block is
coded in inter mode. [0297] k. In one example, whether and how to
apply chroma QP offset lists may depend on whether the current
block is coded in palette mode. [0298] l. In one example, whether
and how to apply chroma QP offset lists may depend on whether the
current block is coded in IBC mode. [0299] m. In one example,
whether and how to apply chroma QP offset lists may depend on
whether the current block is coded in transform skip mode. [0300]
n. In one example, whether and how to apply chroma QP offset lists
may depend on whether the current block is coded in BDPCM mode.
[0301] o. In one example, whether and how to apply chroma QP offset
lists may depend on whether the current block is coded in transform
quant skip or lossless mode.
Regarding Chroma Deblocking at CTU Boundary
[0301] [0302] 28. How to select the QPs (e.g., using corresponding
luma or chroma dequantized QP) utilized in the deblocking filter
process may be dependent on the position of samples relative to the
CTU/CTB/VPDU boundaries. [0303] 29. How to select the QPs (e.g.,
using corresponding luma or chroma dequantized QP) utilized in the
deblocking filter process may depend on color formats (such as RGB
and YCbCr) and/or color sampling format (such as 4:2:0, 4:2:2 and
4:4:4), and/or color down-sampling positions or phases). [0304] 30.
For edges at CTU boundary, the deblocking may be based on luma QP
of the corresponding blocks. [0305] p. In one example, for
horizontal edges at CTU boundary, the deblocking may be based on
luma QP of the corresponding blocks. [0306] i. In one example, the
deblocking may be based on luma QP of the corresponding blocks at
P-side. [0307] ii. In one example, the deblocking may be based on
luma QP of the corresponding blocks at Q-side. [0308] q. In one
example, for vertical edges at CTU boundary, the deblocking may be
based on luma QP of the corresponding blocks. [0309] i. In one
example, the deblocking may be based on luma QP of the
corresponding blocks at P-side. [0310] ii. In one example, the
deblocking may be based on luma QP of the corresponding blocks at
Q-side. [0311] r. In one example, for edges at CTU boundary, the
deblocking may be based on luma QP at P-side and chroma QP at
Q-side. [0312] s. In one example, for edges at CTU boundary, the
deblocking may be based on luma QP at Q-side and chroma QP at
P-side. [0313] t. In this bullet, "CTU boundary" may refer to a
specific CTU boundary such as the upper CTU boundary or the lower
CTU boundary. [0314] 31. For horizontal edges at CTU boundary, the
deblocking may be based on a function of chroma QPs at P-side.
[0315] u. In one example, the deblocking may be based on an
averaging function of chroma QPs at P-side. [0316] i. In one
example, the function may be based on the average of the chroma QPs
for each 8 luma samples. [0317] ii. In one example, the function
may be based on the average of the chroma QPs for each 16 luma
samples. [0318] iii. In one example, the function may be based on
the average of the chroma QPs for each 32 luma samples. [0319] iv.
In one example, the function may be based on the average of the
chroma QPs for each 64 luma samples. [0320] v. In one example, the
function may be based on the average of the chroma QPs for each
CTU. [0321] v. In one example, the deblocking may be based on a
maximum function of chroma QPs at P-side. [0322] i. In one example,
the function may be based on the maximum of the chroma QPs for each
8 luma samples. [0323] ii. In one example, the function may be
based on the maximum of the chroma QPs for each 16 luma samples.
[0324] iii. In one example, the function may be based on the
maximum of the chroma QPs for each 32 luma samples. [0325] iv. In
one example, the function may be based on the maximum of the chroma
QPs for each 64 luma samples. [0326] v. In one example, the
function may be based on the maximum of the chroma QPs for each
CTU. [0327] w. In one example, the deblocking may be based on a
minimum function of chroma QPs at P-side. [0328] i. In one example,
the function may be based on the minimum of the chroma QPs for each
8 luma samples. [0329] ii. In one example, the function may be
based on the minimum of the chroma QPs for each 16 luma samples.
[0330] iii. In one example, the function may be based on the
minimum of the chroma QPs for each 32 luma samples. [0331] iv. In
one example, the function may be based on the minimum of the chroma
QPs for each 64 luma samples. [0332] v. In one example, the
function may be based on the minimum of the chroma QPs for each
CTU. [0333] x. In one example, the deblocking may be based on a sub
sampling function of chroma QPs at P-side. [0334] i. In one
example, the function may be based on the chroma QPs of the k-th
chroma sample for each 8 luma samples. [0335] 1. In one example,
the k-th sample may be the first sample. [0336] 2. In one example,
the k-th sample may be the last sample. [0337] 3. In one example,
the k-th sample may be the third sample. [0338] 4. In one example,
the k-th sample may be the fourth sample. [0339] ii. In one
example, the function may be based on the chroma QPs of the k-th
chroma sample for each 16 luma samples. [0340] 1. In one example,
the k-th sample may be the first sample. [0341] 2. In one example,
the k-th sample may be the last sample. [0342] 3. In one example,
the k-th sample may be the 7-th sample. [0343] 4. In one example,
the k-th sample may be the 8-th sample. [0344] iii. In one example,
the function may be based on the chroma QPs of the k-th chroma
sample for each 32 luma samples. [0345] 1. In one example, the k-th
sample may be the first sample. [0346] 2. In one example, the k-th
sample may be the last sample. [0347] 3. In one example, the k-th
sample may be the 15-th sample. [0348] 4. In one example, the k-th
sample may be the 16-th sample. [0349] iv. In one example, the
function may be based on the chroma QPs of the k-th chroma sample
for each 64 luma samples. [0350] 1. In one example, the k-th sample
may be the first sample. [0351] 2. In one example, the k-th sample
may be the last sample. [0352] 3. In one example, the k-th sample
may be the 31-th sample. [0353] 4. In one example, the k-th sample
may be the 32-th sample. [0354] v. In one example, the function may
be based on the chroma QPs of the k-th chroma sample for each CTU.
[0355] y. Alternatively, the above items may be applied to chroma
QPs at Q-side for deblocking process. [0356] 32. It may be
constrained that QP for chroma component may be the same for a
chroma row segment with length 4*m starting from (4*m*x,2y)
relative to top-left of the picture, where x and y are non-negative
integers; and m is a positive integer. [0357] z. In one example, m
may be equal to 1. [0358] aa. In one example, the width of a
quantization group for chroma component must be no smaller than
4*m. [0359] 33. It may be constrained that QP for chroma component
may be the same for a chroma column segment with length 4*n
starting from (2*x,4*n*y) relative to top-left of the picture,
where x and y are non-negative integers; and n is a positive
integer. [0360] bb. In one example, n may be equal to 1. [0361] cc.
In one example, the height of a quantization group for chroma
component must be no smaller than 4*n.
Regarding Chroma Deblocking Filtering Process
[0361] [0362] 34. A first syntax element controlling the usage of
coding tool X may be signalled in a first video unit (such as
picture header), depending on a second syntax element signalled in
a second video unit (such as SPS or PPS, or VPS). [0363] a. In one
example, the first syntax element is signalled only if the second
syntax element indicates that the coding tool X is enabled. [0364]
b. In one example, X is Bi-Direction Optical Flow (BDOF). [0365] c.
In one example, X is Prediction Refinement Optical Flow (PROF).
[0366] d. In one example, X is Decoder-side Motion Vector
Refinement (DMVR). [0367] e. In one example, the signalling of the
usage of a coding tool X may be under the condition check of slice
types (e.g., P or B slices; non-I slices).
Regarding Chroma Deblocking Filtering Process
[0367] [0368] 35. Deblocking filter decision processes for two
chroma blocks may be unified to be only invoked once and the
decision is applied to two chroma blocks. [0369] b. In one example,
the decision for whether to perform deblocking filter may be same
for Cb and Cr components. [0370] c. In one example, if the
deblocking filter is determined to be applied, the decision for
whether to perform stronger deblocking filter may be same for Cb
and Cr components. [0371] d. In one example, the deblocking
condition and strong filter on/off condition, as described in
section 2.2.7, may be only checked once. However, it may be
modified to check the information of both chroma components. [0372]
i. In one example, the average of gradients of Cb and Cr components
may be used in the above decisions for both Cb and Cr components.
[0373] ii. In one example, the chroma stronger filters may be
performed only when the strong filter condition is satisfied for
both Cb and Cr components. [0374] 1. Alternatively, in one example,
the chroma weak filters may be performed only when the strong
filter condition is not satisfied at least one chroma component
General
[0374] [0375] 36. The above proposed methods may be applied under
certain conditions. [0376] a. In one example, the condition is the
colour format is 4:2:0 and/or 4:2:2. [0377] i. Alternatively,
furthermore, for 4:4:4 colour format, how to apply deblocking
filter to the two colour chroma components may follow the current
design. [0378] b. In one example, indication of usage of the above
methods may be signalled in sequence/picture/slice/tile/brick/a
video region-level, such as SPS/PPS/picture header/slice header.
[0379] c. In one example, the usage of above methods may depend on
[0380] ii. Video contents (e.g. screen contents or natural
contents) [0381] iii. A message signaled in the
DPS/SPS/VPS/PPS/APS/picture header/slice header/tile group
header/Largest coding unit (LCU)/Coding unit (CU)/LCU row/group of
LCUs/TU/PU block/Video coding unit [0382] iv. Position of
CU/PU/TU/block/Video coding unit [0383] a. In one example, for
filtering samples along the CTU/CTB boundaries (e.g., the first K
(e.g., K=4/8) to the top/left/right/bottom boundaries), the
existing design may be applied. While for other samples, the
proposed method (e.g., bullets 3/4) may be applied instead. [0384]
v. Coded modes of blocks containing the samples along the edges
[0385] vi. Transform matrices applied to the blocks containing the
samples along the edges [0386] vii. Block dimension of current
block and/or its neighboring blocks [0387] viii. Block shape of
current block and/or its neighboring blocks [0388] ix. Indication
of the color format (such as 4:2:0, 4:4:4, RGB or YUV) [0389] x.
Coding tree structure (such as dual tree or single tree) [0390] xi.
Slice/tile group type and/or picture type [0391] xii. Color
component (e.g. may be only applied on Cb or Cr) [0392] xiii.
Temporal layer ID [0393] xiv. Profiles/Levels/Tiers of a standard
[0394] xv. Alternatively, m and/or n may be signalled to the
decoder.
5. Additional Embodiments
[0395] The newly added texts are shown in underlined bold
italicized font. The deleted texts are marked by [[]].
5.1. Embodiment #1 on Chroma QP in Deblocking
8.8.3.6 Edge Filtering Process for One Direction
[0396] . . . [0397] Otherwise (cIdx is not equal to 0), the
filtering process for edges in the chroma coding block of current
coding unit specified by cIdx consists of the following ordered
steps: [0398] 1. The variable cQpPicOffset is derived as
follows:
[0398] cQpPicOffset = cIdx == 1 ? pps_cb .times. _qp .times. _offse
.times. t: .times. pps_cr .times. _qp .times. _offset (8-1065)
##EQU00036##
8.8.3.6.3 Decision Process for Chroma Block Edges
[0399] . . . The variables Qp.sub.Q and Qp.sub.P are set equal to
the Qp.sub.Y values of the coding units which include the coding
blocks containing the sample q.sub.0,0 and p.sub.0,0, respectively.
The variable Qp.sub.C is derived as follows:
[ [ q .times. P .times. i = Clip .times. .times. 3 .times. ( 0 , 63
, ( ( Q .times. p Q + Q .times. .times. p P + 1 ) 1 ) +
cQpPicOffset ) (8-1132) Qp C = ChromaQpTable .function. [ cIdx - 1
] .function. [ qPi ] .times. ]] ( 8-1133 ) qPi = ( Q .times. p Q +
Qp P + 1 ) 1 (8-1132) Qp C = ChromaQpTable .function. [ cIdx - 1 ]
.function. [ qPi ] + cQpPicOffset (8-1133) ##EQU00037## [0400]
NOTE--The variable cQpPicOffset provides an adjustment for the
value of pps_cb_qp_offset or pps_cr_qp_offset, according to whether
the filtered chroma component is the Cb or Cr component. However,
to avoid the need to vary the amount of the adjustment within the
picture, the filtering process does not include an adjustment for
the value of slice_cb_qp_offset or slice_cr_qp_offset nor (when
cu_chroma_qp_offset_enabled_flag is equal to 1) for the value of
CuQpOffset.sub.Cb, CuQpOffset.sub.Cr, or CuQpOffset.sub.CbCr. The
value of the variable .beta.' is determined as specified in Table
8-18 based on the quantization parameter Q derived as follows:
[0400] Q = Clip .times. .times. 3 .times. ( 0 , 63 , Qp C + (
slice_beta .times. _offset .times. _div2 1 ) ) (8-1134)
##EQU00038##
where slice_beta_offset_div2 is the value of the syntax element
slice_beta_offset_div2 for the slice that contains sample
q.sub.0,0. The variable .beta. is derived as follows:
.beta. = .beta. ' * .function. ( 1 ( BitDepth C - 8 ) ) (8-1135)
##EQU00039##
The value of the variable t.sub.C' is determined as specified in
Table 8-18 based on the chroma quantization parameter Q derived as
follows:
Q = Clip .times. .times. 3 .times. ( 0 , 65 , Qp C + 2 * .times. (
b .times. S - 1 ) + ( slice_tc .times. _offset .times. _div2 1 ) )
(8-1136) ##EQU00040##
where slice_tc_offset_div2 is the value of the syntax element
slice_tc_offset_div2 for the slice that contains sample q.sub.0,0.
The variable t.sub.C is derived as follows:
t C = ( BitDepth C < 1 .times. 0 ) ? .times. ( t C ' .times. 2 )
( 10 - BitDepth C .times. ): t C ' * .times. ( 1 ( BitDepth C - 8 )
) (8-1137) ##EQU00041##
5.2. Embodiment #2 on Boundary Strength Derivation
8.8.3.5 Derivation Process of Boundary Filtering Strength
[0401] Inputs to this process are: [0402] a picture sample array
recPicture, [0403] a location (xCb,yCb) specifying the top-left
sample of the current coding block relative to the top-left sample
of the current picture, [0404] a variable nCbW specifying the width
of the current coding block, [0405] a variable nCbH specifying the
height of the current coding block, [0406] a variable edgeType
specifying whether a vertical (EDGE_VER) or a horizontal (EDGE_HOR)
edge is filtered, [0407] a variable cIdx specifying the colour
component of the current coding block, [0408] a two-dimensional
(nCbW).times.(nCbH) array edgeFlags. Output of this process is a
two-dimensional (nCbW).times.(nCbH) array bS specifying the
boundary filtering strength. . . . For xD.sub.i with i=0 . . . xN
and yD.sub.j with j=0 . . . yN, the following applies: [0409] If
edgeFlags[xD.sub.i][yD.sub.j] is equal to 0, the variable
bS[xD.sub.i][yD.sub.j] is set equal to 0. [0410] Otherwise, the
following applies: . . . [0411] The variable bS[xD.sub.i][yD.sub.j]
is derived as follows: [0412] If cIdx is equal to 0 and both
samples p.sub.0 and q.sub.0 are in a coding block with
intra_bdpcm_flag equal to 1, bS[xD.sub.i][yD.sub.j] is set equal to
0. [0413] Otherwise, if the sample p.sub.0 or q.sub.0 is in the
coding block of a coding unit coded with intra prediction mode,
bS[xD.sub.i][yD.sub.j] is set equal to 2. [0414] Otherwise, if the
block edge is also a transform block edge and the sample p.sub.0 or
q.sub.0 is in a coding block with ciip_flag equal to 1,
bS[xD.sub.i][yD.sub.j] is set equal to 2. [0415] Otherwise, if the
block edge is also a transform block edge and the sample p.sub.0 or
q.sub.0 is in a transform block which contains one or more non-zero
transform coefficient levels, bS[xD.sub.i][yD.sub.j] is set equal
to 1. [0416] Otherwise, if the block edge is also a transform block
edge, cIdx is greater than 0, and the sample p.sub.0 or q.sub.0 is
in a transform unit with tu_joint_cbcr_residual_flag equal to 1,
bS[xD.sub.i][yD.sub.j] is set equal to 1. [0417] Otherwise, if the
prediction mode of the coding subblock containing the sample
p.sub.0 is different from the prediction mode of the coding
subblock containing the sample q.sub.0 (i.e. one of the coding
subblock is coded in IBC prediction mode and the other is coded in
inter prediction mode), bS[xD.sub.i][yD.sub.j] is set equal to 1
[0418] Otherwise, if cIdx is equal to 0 and one or more of the
following conditions are true, bS[xD.sub.i][yD.sub.j] is set equal
to 1: [0419] [0420] [[The coding subblock containing the sample
p.sub.0 and the coding subblock containing the sample q.sub.0 are
both coded in IBC prediction mode, and the absolute difference
between the horizontal or vertical component of the block vectors
used in the prediction of the two coding subblocks is greater than
or equal to 8 in units of 1/16 luma samples. [0421] For the
prediction of the coding subblock containing the sample p.sub.0
different reference pictures or a different number of motion
vectors are used than for the prediction of the coding subblock
containing the sample q.sub.0. NOTE 1-- The determination of
whether the reference pictures used for the two coding sublocks are
the same or different is based only on which pictures are
referenced, without regard to whether a prediction is formed using
an index into reference picture list 0 or an index into reference
picture list 1, and also without regard to whether the index
position within a reference picture list is different. NOTE 2-- The
number of motion vectors that are used for the prediction of a
coding subblock with top-left sample covering (xSb,ySb), is equal
to PredFlagL0[xSb][ySb]+PredFlagL1[xSb][ySb]. [0422] One motion
vector is used to predict the coding subblock containing the sample
p.sub.0 and one motion vector is used to predict the coding
subblock containing the sample q.sub.0, and the absolute difference
between the horizontal or vertical component of the motion vectors
used is greater than or equal to 8 in units of 1/16 luma samples.
[0423] Two motion vectors and two different reference pictures are
used to predict the coding subblock containing the sample p.sub.0,
two motion vectors for the same two reference pictures are used to
predict the coding subblock containing the sample q.sub.0 and the
absolute difference between the horizontal or vertical component of
the two motion vectors used in the prediction of the two coding
subblocks for the same reference picture is greater than or equal
to 8 in units of 1/16 luma samples. [0424] Two motion vectors for
the same reference picture are used to predict the coding subblock
containing the sample p.sub.0, two motion vectors for the same
reference picture are used to predict the coding subblock
containing the sample q.sub.0 and both of the following conditions
are true: The absolute difference between the horizontal or
vertical component of list 0 motion vectors used in the prediction
of the two coding subblocks is greater than or equal to 8 in 1/16
luma samples, or the absolute difference between the horizontal or
vertical component of the list 1 motion vectors used in the
prediction of the two coding subblocks is greater than or equal to
8 in units of 1/16 luma samples. The absolute difference between
the horizontal or vertical component of list 0 motion vector used
in the prediction of the coding subblock containing the sample
p.sub.0 and the list 1 motion vector used in the prediction of the
coding subblock containing the sample q.sub.0 is greater than or
equal to 8 in units of 1/16 luma samples, or the absolute
difference between the horizontal or vertical component of the list
1 motion vector used in the prediction of the coding subblock
containing the sample p.sub.0 and list 0 motion vector used in the
prediction of the coding subblock containing the sample q.sub.0 is
greater than or equal to 8 in units of 1/16 luma samples.]] [0425]
Otherwise, the variable bS[xD.sub.i][yD.sub.j] is set equal to
0.
5.3. Embodiment #3 on Boundary Strength Derivation
8.8.3.5 Derivation Process of Boundary Filtering Strength
[0426] Inputs to this process are: [0427] a picture sample array
recPicture, [0428] a location (xCb,yCb) specifying the top-left
sample of the current coding block relative to the top-left sample
of the current picture, [0429] a variable nCbW specifying the width
of the current coding block, [0430] a variable nCbH specifying the
height of the current coding block, [0431] a variable edgeType
specifying whether a vertical (EDGE_VER) or a horizontal (EDGE_HOR)
edge is filtered, [0432] a variable cIdx specifying the colour
component of the current coding block, [0433] a two-dimensional
(nCbW).times.(nCbH) array edgeFlags. Output of this process is a
two-dimensional (nCbW).times.(nCbH) array bS specifying the
boundary filtering strength. . . . For xD.sub.i with i=0 . . . xN
and yD.sub.j with j=0 . . . yN, the following applies: [0434] If
edgeFlags[xD.sub.i][yD.sub.j] is equal to 0, the variable
bS[xD.sub.i][yD.sub.j] is set equal to 0. [0435] Otherwise, the
following applies: . . . [0436] The variable bS[xD.sub.i][yD.sub.j]
is derived as follows: [0437] If cIdx is equal to 0 and both
samples p.sub.0 and q.sub.0 are in a coding block with
intra_bdpcm_flag equal to 1, bS[xD.sub.i][yD.sub.j] is set equal to
0. [0438] Otherwise, if the sample p.sub.0 or q.sub.0 is in the
coding block of a coding unit coded with intra prediction mode,
bS[xD.sub.i][yD.sub.j] is set equal to 2. [0439] Otherwise, if the
block edge is also a transform block edge and the sample p.sub.0 or
q.sub.0 is in a coding block with ciip_flag equal to 1,
bS[xD.sub.i][yD.sub.j] is set equal to 2. [0440] Otherwise, if the
block edge is also a transform block edge and the sample p.sub.0 or
q.sub.0 is in a transform block which contains one or more non-zero
transform coefficient levels, bS[xD.sub.i][y ID.sub.j] is set equal
to 1. [0441] [[Otherwise, if the block edge is also a transform
block edge, cIdx is greater than 0, and the sample p.sub.0 or
q.sub.0 is in a transform unit with tu_joint_cbcr_residual_flag
equal to 1, bS[xD.sub.i][yD.sub.j] is set equal to 1.]] [0442]
Otherwise, if the prediction mode of the coding subblock containing
the sample p.sub.0 is different from the prediction mode of the
coding subblock containing the sample q.sub.0 (i.e. one of the
coding subblock is coded in IBC prediction mode and the other is
coded in inter prediction mode), bS[xD.sub.i][yD.sub.j] is set
equal to 1 [0443] Otherwise, if cIdx is equal to 0 and one or more
of the following conditions are true, bS[xD.sub.i][yD.sub.j] is set
equal to 1: [0444] The coding subblock containing the sample
p.sub.0 and the coding subblock containing the sample q.sub.0 are
both coded in IBC prediction mode, and the absolute difference
between the horizontal or vertical component of the block vectors
used in the prediction of the two coding subblocks is greater than
or equal to 8 in units of 1/16 luma samples. [0445] For the
prediction of the coding subblock containing the sample p.sub.0
different reference pictures or a different number of motion
vectors are used than for the prediction of the coding subblock
containing the sample q.sub.0. [0446] NOTE 1-- The determination of
whether the reference pictures used for the two coding sublocks are
the same or different is based only on which pictures are
referenced, without regard to whether a prediction is formed using
an index into reference picture list 0 or an index into reference
picture list 1, and also without regard to whether the index
position within a reference picture list is different. [0447] NOTE
2-- The number of motion vectors that are used for the prediction
of a coding subblock with top-left sample covering (xSb,ySb), is
equal to PredFlagL0[xSb][ySb]+PredFlagL1[xSb][ySb]. [0448] One
motion vector is used to predict the coding subblock containing the
sample p.sub.0 and one motion vector is used to predict the coding
subblock containing the sample q.sub.0, and the absolute difference
between the horizontal or vertical component of the motion vectors
used is greater than or equal to 8 in units of 1/16 luma samples.
[0449] Two motion vectors and two different reference pictures are
used to predict the coding subblock containing the sample p.sub.0,
two motion vectors for the same two reference pictures are used to
predict the coding subblock containing the sample q.sub.0 and the
absolute difference between the horizontal or vertical component of
the two motion vectors used in the prediction of the two coding
subblocks for the same reference picture is greater than or equal
to 8 in units of 1/16 luma samples. [0450] Two motion vectors for
the same reference picture are used to predict the coding subblock
containing the sample p.sub.0, two motion vectors for the same
reference picture are used to predict the coding subblock
containing the sample q.sub.0 and both of the following conditions
are true: [0451] The absolute difference between the horizontal or
vertical component of list 0 motion vectors used in the prediction
of the two coding subblocks is greater than or equal to 8 in 1/16
luma samples, or the absolute difference between the horizontal or
vertical component of the list 1 motion vectors used in the
prediction of the two coding subblocks is greater than or equal to
8 in units of 1/16 luma samples. [0452] The absolute difference
between the horizontal or vertical component of list 0 motion
vector used in the prediction of the coding subblock containing the
sample p.sub.0 and the list 1 motion vector used in the prediction
of the coding subblock containing the sample q.sub.0 is greater
than or equal to 8 in units of 1/16 luma samples, or the absolute
difference between the horizontal or vertical component of the list
1 motion vector used in the prediction of the coding subblock
containing the sample p.sub.0 and list 0 motion vector used in the
prediction of the coding subblock containing the sample q.sub.0 is
greater than or equal to 8 in units of 1/16 luma samples. [0453]
Otherwise, the variable bS[xD.sub.i][yD.sub.j] is set equal to
0.
5.4. Embodiment #4 on Luma Deblocking Filtering Process
8.8.3.6.1 Decision Process for Luma Block Edges
[0454] Inputs to this process are: [0455] a picture sample array
recPicture, [0456] a location (xCb,yCb) specifying the top-left
sample of the current coding block relative to the top-left sample
of the current picture, [0457] a location (xBl,yBl) specifying the
top-left sample of the current block relative to the top-left
sample of the current coding block, [0458] a variable edgeType
specifying whether a vertical (EDGE_VER) or a horizontal (EDGE_HOR)
edge is filtered, [0459] a variable bS specifying the boundary
filtering strength, [0460] a variable maxFilterLengthP specifying
the max filter length, [0461] a variable maxFilterLengthQ
specifying the max filter length. Outputs of this process are:
[0462] the variables dE, dEp and dEq containing decisions, [0463]
the modified filter length variables maxFilterLengthP and
maxFilterLengthQ, [0464] the variable t.sub.C. . . . The following
ordered steps apply: . . . [0465] 1. When sidePisLargeBlk or
sideQisLargeBlk is greater than 0, the following applies: [0466] a.
The variables dp0L, dp3L are derived and maxFilterLengthP is
modified as follows: [0467] [[If sidePisLargeBlk is equal to 1, the
following applies:
[0467] d .times. p .times. 0 .times. L = ( d .times. .times. p
.times. .times. 0 + Abs .function. ( p 5 , 0 - 2 * .times. p 4 , 0
+ p 3 , 0 ) + 1 ) 1 (8-1087) d .times. .times. p .times. .times. 3
.times. L = ( d .times. .times. p .times. .times. 3 + Abs
.function. ( p 5 , 3 - 2 * .times. p 4 , 3 + p 3 , 3 ) + 1 ) 1
(8-1088) ##EQU00042## [0468] Otherwise, the following
applies:]]
[0468] d .times. p .times. 0 .times. L = d .times. .times. p
.times. .times. 0 (8-1089) d .times. .times. p .times. .times. 3
.times. L = d .times. .times. p .times. .times. 3 (8-1090) [ [ max
.times. FilterLengthP = 3 ] ] (8-1091) ##EQU00043## [0469] b. The
variables dq0L and dq3L are derived as follows: [0470] [[If
sideQisLargeBlk is equal to 1, the following applies:
[0470] d .times. q .times. 0 .times. L = ( d .times. q .times. 0 +
Abs .times. ( q 5 , 0 - 2 * q 4 , 0 + q 3 , 0 ) + 1 ) >> 1 (
8 .times. .times. 1092 ) ##EQU00044## dq .times. 3 .times. L = ( dq
.times. 3 + Abs .function. ( q 5 , 3 - 2 * q 4 , 3 + q 3 , 3 ) + 1
) >> 1 ( 8 .times. .times. 1093 ) ##EQU00044.2## [0471]
Otherwise, the following applies:]]
[0471] d .times. q .times. 0 .times. L = dq .times. 0 ( 8 .times.
.times. 1094 ) ##EQU00045## dq .times. 3 .times. L = d .times. q
.times. 3 ( 8 .times. .times. 1095 ) ##EQU00045.2##
. . . [0472] 2. The variables dE, dEp and dEq are derived as
follows: . . .
5.5. Embodiment #5 on Chroma Deblocking Filtering Process
8.8.3.6.3 Decision Process for Chroma Block Edges
[0473] This process is only invoked when ChromaArrayType is not
equal to 0. Inputs to this process are: [0474] a chroma picture
sample array recPicture, [0475] a chroma location (xCb,yCb)
specifying the top-left sample of the current chroma coding block
relative to the top-left chroma sample of the current picture,
[0476] a chroma location (xBl,yBl) specifying the top-left sample
of the current chroma block relative to the top-left sample of the
current chroma coding block, [0477] a variable edgeType specifying
whether a vertical (EDGE_VER) or a horizontal (EDGE_HOR) edge is
filtered, [0478] a variable cIdx specifying the colour component
index, [0479] a variable cQpPicOffset specifying the picture-level
chroma quantization parameter offset, [0480] a variable bS
specifying the boundary filtering strength, [0481] a variable
maxFilterLengthCbCr. Outputs of this process are [0482] the
modified variable maxFilterLengthCbCr, [0483] the variable t.sub.C.
The variable maxK is derived as follows: [0484] If edgeType is
equal to EDGE_VER, the following applies:
[0484] max .times. K = ( SubHeight .times. C == 1 ) ? 3 : 1 ( 8
.times. .times. 1124 ) ##EQU00046## [0485] Otherwise (edgeType is
equal to EDGE_HOR), the following applies:
[0485] max .times. K = ( S .times. ubWidhtC = = 1 ) ? 3 : 1 ( 8
.times. .times. 1125 ) ##EQU00047##
The values p.sub.i and q.sub.i with i=0 . . . maxFilterLengthCbCr
and k=0 . . . maxK are derived as follows: [0486] If edgeType is
equal to EDGE_VER, the following applies::
[0486] q i , k = recPicture [ xCb + xB .times. l + i ] [ y .times.
C .times. b + yB .times. l + k ] ( 8 .times. .times. 1126 )
##EQU00048## p i , k = recPicture [ xCb + x .times. B .times. l - i
- 1 ] [ y .times. C .times. b + y .times. B .times. l + k ] ( 8
.times. .times. 1127 ) ##EQU00048.2## subSampleC = SubHeightC ( 8
.times. .times. 1128 ) ##EQU00048.3## [0487] Otherwise (edgeType is
equal to EDGE_HOR), the following applies:
[0487] q i , k = recPicture [ xCb + x .times. B .times. l + k ] [ y
.times. C .times. b + y .times. B .times. l + i ] ( 8 .times.
.times. 1129 ) ##EQU00049## p i , k = recPicture [ xCb + x .times.
B .times. l + k ] [ y .times. C .times. b + y .times. B .times. l -
i - 1 ] ( 8 .times. .times. 1130 ) ##EQU00049.2## subSampleC =
SubHeightC ( 8 .times. .times. 1131 ) ##EQU00049.3##
[0488] [0489]
[0489] [0490]
[0490] The value of the variable .beta. is determined as specified
in Table t-18 based on the quantization parameter Q derived as
follows:
Q = Clip .times. 3 .times. ( 0 , 6 .times. 3 , Q .times. p C + (
slice_beta .times. _offset .times. _div2 .times. << 1 ) ) ( 8
.times. .times. 1134 ) ##EQU00050##
where slice_beta_offset_div2 is the value of the syntax element
slice_beta_offset_div2 for the slice that contains sample
q.sub.0,0. The variable .beta. is derived as follows:
.beta. = .beta. ' * ( 1 .times. << ( BitDepth C - 8 ) ) ( 8
.times. .times. 1135 ) ##EQU00051##
The value of the variable t.sub.C' is determined as specified in
Table 8-18 based on the chroma quantization parameter Q derived as
follows:
Q = Clip .times. 3 .times. ( 0 , 6 .times. 5 , Q .times. p C + 2 *
( b .times. S - 1 ) + ( slice_tc .times. _offset .times. _div2
.times. << 1 ) ) ( 8 .times. .times. 1136 ) ##EQU00052##
where slice_tc_offset_div2 is the value of the syntax element
slice_tc_offset_div2 for the slice that contains sample q.sub.0,0.
The variable t.sub.C is derived as follows:
t C = ( B .times. itDepth C < 10 ) ? ( t C ' + 2 ) >> ( 10
- BitDepth C ) : t C ' * 1 .times. << ( BitDepth C - 8 ) ( 8
.times. .times. 1137 ) ##EQU00053##
When maxFilterLengthCbCr is equal to 1 and bS is not equal to 2,
maxFilterLengthCbCr is set equal to 0.
5.6. Embodiment #6 on Chroma QP in Deblocking
8.8.3.6.3 Decision Process for Chroma Block Edges
[0491] This process is only invoked when ChromaArrayType is not
equal to 0. Inputs to this process are: [0492] a chroma picture
sample array recPicture, [0493] a chroma location (xCb,yCb)
specifying the top-left sample of the current chroma coding block
relative to the top-left chroma sample of the current picture,
[0494] a chroma location (xBl,yBl) specifying the top-left sample
of the current chroma block relative to the top-left sample of the
current chroma coding block, [0495] a variable edgeType specifying
whether a vertical (EDGE_VER) or a horizontal (EDGE_HOR) edge is
filtered, [0496] a variable cIdx specifying the colour component
index, [0497] a variable cQpPicOffset specifying the picture-level
chroma quantization parameter offset, [0498] a variable bS
specifying the boundary filtering strength, [0499] a variable
maxFilterLengthCbCr. Outputs of this process are [0500] the
modified variable maxFilterLengthCbCr, [0501] the variable t.sub.C.
The variable maxK is derived as follows: [0502] If edgeType is
equal to EDGE_VER, the following applies:
[0502] max .times. K = ( SubHeight .times. C == 1 ) ? 3 : 1 ( 8
.times. .times. 1124 ) ##EQU00054## [0503] Otherwise (edgeType is
equal to EDGE_HOR), the following applies:
[0503] max .times. K = ( S .times. ubWidhtC = = 1 ) ? 3 : 1 ( 8
.times. .times. 1125 ) ##EQU00055##
The values p.sub.1 and q.sub.i with i=0 . . . maxFilterLengthCbCr
and k=0 . . . maxK are derived as follows: [0504] If edgeType is
equal to EDGE_VER, the following applies::
[0504] q i , k = recPicture [ xCb + xB .times. l + i ] [ y .times.
C .times. b + yB .times. l + k ] ( 8 .times. .times. 1126 )
##EQU00056## p i , k = recPicture [ xCb + x .times. B .times. l - i
- 1 ] [ y .times. C .times. b + y .times. B .times. l + k ] ( 8
.times. .times. 1127 ) ##EQU00056.2## subSampleC = SubHeightC ( 8
.times. .times. 1128 ) ##EQU00056.3## [0505] Otherwise (edgeType is
equal to EDGE_HOR), the following applies:
[0505] q i , k = recPicture [ xCb + x .times. B .times. l + k ] [ y
.times. C .times. b + y .times. B .times. l + i ] ( 8 .times.
.times. 1129 ) ##EQU00057## p i , k = recPicture [ xCb + x .times.
B .times. l + k ] [ y .times. C .times. b + y .times. B .times. l -
i - 1 ] ( 8 .times. .times. 1130 ) ##EQU00057.2## subSampleC =
SubHeightC ( 8 .times. .times. 1131 ) ##EQU00057.3##
The variables Qp.sub.Q and Qp.sub.P are set equal to the Qp.sub.Y
values of the coding units which include the coding blocks
containing the sample q.sub.0,0 and p.sub.0,0, respectively. The
variable Qp.sub.C is derived as follows:
[ [ qPi = Clip .times. 3 .times. ( 0 , 6 .times. 3 , ( ( Q .times.
p Q + Q .times. p P + 1 ) >> 1 ) + cQpPicOffset ) ( 8 .times.
.times. 1132 ) ] ] ##EQU00058##
Q .times. p C = ChromaQpTable .function. [ cIdx - 1 ] .function. [
qPi ] (8-1133) ##EQU00059## [0506] NOTE--The variable cQpPicOffset
provides an adjustment for the value of pps_cb_qp_offset or
pps_cr_qp_offset, according to whether the filtered chroma
component is the Cb or Cr component. However, to avoid the need to
vary the amount of the adjustment within the picture, the filtering
process does not include an adjustment for the value of
slice_cb_qp_offset or slice_cr_qp_offset nor (when
cu_chroma_qp_offset_enabled_flag is equal to 1) for the value of
CuQpOffset.sub.Cb, CuQpOffset.sub.Cr, or CuQpOffset.sub.CbCr. . .
.
5.7. Embodiment #7 on Chroma QP in Deblocking
8.8.3.6.3 Decision Process for Chroma Block Edges
[0507] This process is only invoked when ChromaArrayType is not
equal to 0. Inputs to this process are: [0508] a chroma picture
sample array recPicture, [0509] a chroma location (xCb,yCb)
specifying the top-left sample of the current chroma coding block
relative to the top -left chroma sample of the current picture, . .
. Outputs of this process are [0510] the modified variable
maxFilterLengthCbCr, [0511] the variable t.sub.C. The variable maxK
is derived as follows: [0512] If edgeType is equal to EDGE_VER, the
following applies:
[0512] max .times. K = ( SubHeightC == 1 ) ? 3:1 (8-1124)
##EQU00060## [0513] Otherwise (edgeType is equal to EDGE_HOR), the
following applies:
[0513] max .times. K = ( SubWidthC == 1 ) ? 3:1 (8-1125)
##EQU00061##
The values p.sub.i and q.sub.i with i=0 . . . maxFilterLengthCbCr
and k=0 . . . maxK are derived as follows: [0514] If edgeType is
equal to EDGE_VER, the following applies::
[0514] q i , k = recPicture .function. [ xCb + x .times. B .times.
l + i ] .function. [ y .times. C .times. b + y .times. B .times. l
+ k ] (8-1126) p i , k = recPicture .function. [ xCb + x .times. B
.times. l - i - 1 ] .function. [ y .times. C .times. b + y .times.
B .times. l + k ] (8-1127) subSampleC = SubHeightC (8-1128)
##EQU00062## [0515] Otherwise (edgeType is equal to EDGE_HOR), the
following applies:
[0515] q i , k = recPicture .function. [ x .times. .times. C
.times. .times. b + x .times. .times. B .times. .times. l + k ]
.function. [ y .times. C .times. b + y .times. B .times. l + i ]
(8-1129) p i , k = recPicture .function. [ x .times. .times. C
.times. .times. b + x .times. .times. B .times. .times. l + k ]
.function. [ y .times. C .times. b + y .times. B .times. l - i - 1
] (8-1130) subSampleC = SubHeightC (8-1131) ##EQU00063##
[[The variables Qp.sub.Q and Qp.sub.P are set equal to the Qp.sub.Y
values of the coding units which include the coding blocks
containing the sample q.sub.0,0 and p.sub.0,0, respectively.]] The
variable Qp.sub.C is derived as follows:
q .times. P .times. i = Clip .times. .times. 3 .times. ( 0 , 63 , (
( Q .times. p Q + Q .times. .times. p P + 1 ) 1 ) + cQpPicOffset )
(8-1132) Qp C = ChromaQpTable .function. [ cIdx - 1 ] .function. [
qPi ] (8-1133) ##EQU00064## [0516] NOTE--The variable cQpPicOffset
provides an adjustment for the value of pps_cb_qp_offset or
pps_cr_qp_offset, according to whether the filtered chroma
component is the Cb or Cr component. However, to avoid the need to
vary the amount of the adjustment within the picture, the filtering
process does not include an adjustment for the value of
slice_cb_qp_offset or slice_cr_qp_offset nor (when
cu_chroma_qp_offset_enabled_flag is equal to 1) for the value of
CuQpOffset.sub.Cb, CuQpOffset.sub.Cr, or CuQpOffset.sub.CbCr. The
value of the variable .beta. is determined as specified in Table
8-18 based on the quantization parameter Q derived as follows:
[0516] Q = Clip .times. .times. 3 .times. ( 0 , 63 , Qp C + (
slice_beta .times. _offset .times. _div2 1 ) ) (8-1134)
##EQU00065##
where slice_beta_offset_div2 is the value of the syntax element
slice_beta_offset_div2 for the slice that contains sample
q.sub.0,0. The variable .beta. is derived as follows:
.beta. = .beta. .times. ' * ( 1 ( BitDepth C - 8 ) ) (8-1135)
##EQU00066##
The value of the variable t.sub.C' is determined as specified in
Table 8-18 based on the chroma quantization parameter Q derived as
follows:
Q = Clip .times. .times. 3 .times. ( 0 , 65 , Qp C + 2 * .times. (
b .times. S - 1 ) + ( slice_tc .times. _offset .times. _div2 1 ) )
(8-1136) ##EQU00067##
where slice_tc_offset_div2 is the value of the syntax element
slice_tc_offset_div2 for the slice that contains sample
q.sub.0,0.
5.8. Embodiment #8 on Chroma QP in Deblocking
[0517] When making filter decisions for the depicted three samples
(with solid circles), the QPs of the luma CU that covers the center
position of the chroma CU including the three samples is selected.
Therefore, for the 1.sup.st, 2.sup.nd, and 3.sup.rd chroma sample
(depicted in FIG. 11), only the QP of CU.sub.Y3 is utilized,
respectively.
[0518] In this way, how to select luma CU for chroma
quantization/dequantization process is aligned with that for chroma
filter decision process.
5.9. Embodiment #9 on QP Used for JCCR Coded Blocks
8.7.3 Scaling Process for Transform Coefficients
[0519] Inputs to this process are: [0520] a luma location
(xTbY,yTbY) specifying the top-left sample of the current luma
transform block relative to the top-left luma sample of the current
picture, [0521] a variable nTbW specifying the transform block
width, [0522] a variable nTbH specifying the transform block
height, [0523] a variable cIdx specifying the colour component of
the current block, [0524] a variable bitDepth specifying the bit
depth of the current colour component. Output of this process is
the (nTbW).times.(nTbH) array d of scaled transform coefficients
with elements d[x][y]. The quantization parameter qP is derived as
follows: [0525] If cIdx is equal to 0 and
transform_skip_flag[xTbY][yTbY] is equal to 0, the following
applies:
[0525] qP = Qp ' Y ( 8 - 950 ) ##EQU00068## [0526] Otherwise, if
cIdx is equal to 0 (and transform_skip_flag[xTbY][yTbY] is equal to
1), the following applies:
[0526] q .times. P = Max .function. ( QpPrimeTs .times. Min , Qp '
Y ) (8-951) ##EQU00069## [0527] Otherwise, if
TuCResMode[xTbY][yTbY] is unequal to [[equal to 2]], the following
applies:
[0527] q .times. P = Qp ' C .times. b .times. C .times. r (8-952)
##EQU00070## [0528] Otherwise, if cIdx is equal to 1, the following
applies:
[0528] q .times. P = Qp ' C .times. b (8-953) ##EQU00071## [0529]
Otherwise (cIdx is equal to 2), the following applies:
[0529] q .times. P = Qp ' C .times. r (8-954) ##EQU00072##
5.10 Embodiment #10 on QP Used for JCCR Coded Blocks
8.8.3.2 Deblocking Filter Process for One Direction
[0530] Inputs to this process are: [0531] the variable treeType
specifying whether the luma (DUAL_TREE_LUMA) or chroma components
(DUAL_TREE_CHROMA) are currently processed, [0532] when treeType is
equal to DUAL_TREE_LUMA, the reconstructed picture prior to
deblocking, i.e., the array recPicture.sub.L, [0533] when
ChromaArrayType is not equal to 0 and treeType is equal to
DUAL_TREE_CHROMA, the arrays recPicture.sub.Cb and
recPicture.sub.Cr, [0534] a variable edgeType specifying whether a
vertical (EDGE_VER) or a horizontal (EDGE_HOR) edge is filtered.
Outputs of this process are the modified reconstructed picture
after deblocking, i.e: [0535] when treeType is equal to
DUAL_TREE_LUMA, the array recPicture.sub.L, [0536] when
ChromaArrayType is not equal to 0 and treeType is equal to
DUAL_TREE_CHROMA, the arrays recPicture.sub.Cb and
recPicture.sub.Cr. The variables firstCompIdx and lastCompIdx are
derived as follows:
[0536] firstCompIdx = ( treeType == DUAL_TREE .times. _CHROMA ) ?
1:0 (8-1022) lastCompIdx = ( treeType == DUAL_TREE .times. _LUMA
.times. ChromaArrayType == 0 ) ? 0:2 ( 8 - 1023 ) ##EQU00073##
For each coding unit and each coding block per colour component of
a coding unit indicated by the colour component index cIdx ranging
from firstCompIdx to lastCompIdx, inclusive, with coding block
width nCbW, coding block height nCbH and location of top-left
sample of the coding block (xCb,yCb), when cIdx is equal to 0, or
when cIdx is not equal to 0 and edgeType is equal to EDGE_VER and
xCb % 8 is equal 0, or when cIdx is not equal to 0 and edgeType is
equal to EDGE_HOR and yCb % 8 is equal to 0, the edges are filtered
by the following ordered steps: . . . [[5. The picture sample array
recPicture is derived as follows: [0537] If cIdx is equal to 0,
recPicture is set equal to the reconstructed luma picture sample
array prior to deblocking recPicture.sub.L. [0538] Otherwise, if
cIdx is equal to 1, recPicture is set equal to the reconstructed
chroma picture sample array prior to deblocking recPicture.sub.Cb.
[0539] Otherwise (cIdx is equal to 2), recPicture is set equal to
the reconstructed chroma picture sample array prior to deblocking
recPicture.sub.Cr]]
[0539] . . . [0540] The edge filtering process for one direction is
invoked for a coding block as specified in clause 8.8.3.6 with the
variable edgeType, the variable cIdx, the reconstructed picture
prior to deblocking recPicture, the location (xCb,yCb), the coding
block width nCbW, the coding block height nCbH, and the arrays bS,
maxFilterLengthPs, and maxFilterLengthQs, as inputs, and the
modified reconstructed picture recPicture as output.
8.8.3.5 Derivation Process of Boundary Filtering Strength
[0541] Inputs to this process are: [0542] a picture sample array
recPicture, [0543] a location (xCb,yCb) specifying the top-left
sample of the current coding block relative to the top-left sample
of the current picture, [0544] a variable nCbW specifying the width
of the current coding block, [0545] a variable nCbH specifying the
height of the current coding block, [0546] a variable edgeType
specifying whether a vertical (EDGE_VER) or a horizontal (EDGE_HOR)
edge is filtered, [0547] a variable cIdx specifying the colour
component of the current coding block, [0548] a two-dimensional
(nCbW).times.(nCbH) array edgeFlags. Output of this process is a
two-dimensional (nCbW).times.(nCbH) array bS specifying the
boundary filtering strength. The variables xD.sub.i, yD.sub.j, xN
and yN are derived as follows: . . . For xD.sub.i with i=0 . . . xN
and yD.sub.j with j=0 . . . yN, the following applies: [0549] If
edgeFlags[xD.sub.i][yD.sub.j] is equal to 0, the variable
bS[xD.sub.i][yD.sub.j] is set equal to 0. [0550] Otherwise, the
following applies: [0551] The sample values p.sub.0 and q.sub.0 are
derived as follows: [0552] If edgeType is equal to EDGE_VER,
p.sub.0 is set equal to recPicturexCb+xD.sub.i1][yCb+yD.sub.j] and
q.sub.0 is set equal to recPicture[xCb+xD.sub.i][yCb+yD.sub.j].
[0553] Otherwise (edgeType is equal to EDGE_HOR), p.sub.0 is set
equal to recPicture[xCb+xD.sub.i][yCb+yD.sub.j1] and q.sub.0 is set
equal to recPicture[xCb+xD.sub.i][yCb+yD.sub.j]. . . .
8.8.3.6 Edge Filtering Process for One Direction
[0554] Inputs to this process are: [0555] a variable edgeType
specifying whether vertical edges (EDGE_VER) or horizontal edges
(EDGE_HOR) are currently processed, [0556] a variable cIdx
specifying the current colour component, [0557] the reconstructed
picture prior to deblocking recPicture, [0558] a location (xCb,yCb)
specifying the top-left sample of the current coding block relative
to the top-left sample of the current picture, [0559] a variable
nCbW specifying the width of the current coding block, [0560] a
variable nCbH specifying the height of the current coding block,
[0561] the array bS specifying the boundary strength, [0562] the
arrays maxFilterLengthPs and maxFilterLengthQs. Output of this
process is the modified reconstructed picture after deblocking
recPicture.sub.i. . . . [0563] Otherwise (cIdx is not equal to 0),
the filtering process for edges in the chroma coding block of
current coding unit specified by cIdx consists of the following
ordered steps: [0564] 1. The variable cQpPicOffset is derived as
follows:
[0564] [0565] 2. [0566] 3. The decision process for chroma block
edges as specified in clause 8.8.3.6.3 is invoked with the chroma
picture sample array recPicture, the location of the chroma coding
block (xCb,yCb), the location of the chroma block (xBl,yBl) set
equal to (xD.sub.k,yD.sub.m), the edge direction edgeType, the
variable cQpPicOffset, the boundary filtering strength
bS[xD.sub.k][yD.sub.m], and the variable maxFilterLengthCbCr set
equal to maxFilterLengthPs[xD.sub.k][yD.sub.m] as inputs, and the
modified variable maxFilterLengthCbCr, and the variable t.sub.C as
outputs. [0567] 4. When maxFilterLengthCbCr is greater than 0, the
filtering process for chroma block edges as specified in clause
8.8.3.6.4 is invoked with the chroma picture sample array
recPicture, the location of the chroma coding block (xCb,yCb), the
chroma location of the block (xBl,yBl) set equal to
(xD.sub.k,yD.sub.m), the edge direction edgeType, the variable
maxFilterLengthCbC and the variable t.sub.C as inputs, and the
modified chroma picture sample array recPicture as output.
[0568]
8.8.3.6.3 Decision Process for Chroma Block Edges
[0569] This process is only invoked when ChromaArrayType is not
equal to 0. Inputs to this process are: [0570] a chroma picture
sample array recPicture, [0571] a chroma location (xCb,yCb)
specifying the top-left sample of the current chroma coding block
relative to the top-left chroma sample of the current picture,
[0572] a chroma location (xBl,yBl) specifying the top-left sample
of the current chroma block relative to the top-left sample of the
current chroma coding block, [0573] a variable edgeType specifying
whether a vertical (EDGE_VER) or a horizontal (EDGE_HOR) edge is
filtered, [0574] [[a variable cIdx specifying the colour component
index,]] [0575] a variable cQpPicOffset specifying the
picture-level chroma quantization parameter offset, [0576] a
variable bS specifying the boundary filtering strength, [0577] a
variable maxFilterLengthCbCr. Outputs of this process are [0578]
the modified variable maxFilterLengthCbCr, [0579] the variable
t.sub.C. The variable maxK is derived as follows: [0580] If
edgeType is equal to EDGE_VER, the following applies:
[0580] max .times. K = ( SubHeigtC == 1 ) ? 3 : 1 ( 8 - 1124 )
##EQU00074## [0581] Otherwise (edgeType is equal to EDGE_HOR), the
following applies:
[0581] max .times. K = ( SubWidthC == 1 ) ? 3 : 1 ( 8 - 1125 )
##EQU00075##
The values p.sub.i and q.sub.i with i=0 . . . maxFilterLengthCbCr
and k=0 . . . maxK are derived as follows: [0582] If edgeType is
equal to EDGE_VER, the following applies::
[0582] ( 8 - 1126 ) ##EQU00076## q .times. i , k = recPicture xCb +
xB .times. 1 + i ] [ yCb + yB .times. 1 + k ] ##EQU00076.2## ( 8 -
1127 ) ##EQU00076.3## p i , k = recPicture .times. [ xCb + xB
.times. 1 - i - 1 ] [ yCb + yB .times. 1 + k ] ##EQU00076.4##
subSampleC = SubHeightC ( 8 - 1128 ) ##EQU00076.5## [0583]
Otherwise (edgeType is equal to EDGE_HOR), the following
applies:
[0583] q = recPicture .times. [ xCb + xB .times. 1 + k ] [ yCb + yB
.times. 1 + i ] ( 8 - 1129 ) ##EQU00077## p = recPicture .times. [
xCb + xB .times. 1 + k ] [ yCb + yB .times. 1 - i - 1 ] ( 8 - 1130
) ##EQU00077.2## subSampleC = SubWidthC ( 8 - 1131 )
##EQU00077.3##
The variables Qp.sub.Q and Qp.sub.P are set equal to the Qp.sub.Y
values of the coding units which include the coding blocks
containing the sample q.sub.0,0 and p.sub.0,0, respectively. The
variable Qp.sub.C is derived as follows:
qPi=(Qp.sub.Q+Qp.sub.P+1)>>1) (8-1132)
[0584] NOTE--The variable cQpPicOffset provides an adjustment for
the value of pps_cb_qp_offset or pps_cr_qp_offset, according to
whether the filtered chroma component is the Cb or Cr component.
However, to avoid the need to vary the amount of the adjustment
within the picture, the filtering process does not include an
adjustment for the value of slice_cb_qp_offset or
slice_cr_qp_offset nor (when cu_chroma_qp_offset_enabled_flag is
equal to 1) for the value of CuQpOffset.sub.Cb, CuQpOffset.sub.Cr,
or CuQpOffset.sub.CbCr. The value of the variable .beta. is
determined as specified in Table 8-18 based on the quantization
parameter Q derived as follows:
[0584] Q = Clip .times. 3 .times. ( 0 , 63 , Qp C + ( slice_beta
.times. _offset .times. _div2 1 ) ) ( 8 - 1134 ) ##EQU00078##
where slice_beta_offset_div2 is the value of the syntax element
slice_beta_offset_div2 for the slice that contains sample
q.sub.0,0. The variable .beta. is derived as follows:
.beta. = .beta. ' * ( 1 ( BitDepth C - 8 ) ) ( 8 - 1135 )
##EQU00079##
The value of the variable t.sub.C' is determined as specified in
Table 8-18 based on the chroma quantization parameter Q derived as
follows:
Q = Clip .times. 3 .times. ( 0 , 65 , Qp C + 2 * ( b .times. S - 1
) + ( slice_tc .times. _offset .times. _div2 1 ) ) ( 8 - 1136 )
##EQU00080##
where slice_tc_offset_div2 is the value of the syntax element
slice_tc_offset_div2 for the slice that contains sample q.sub.0,0.
The variable t.sub.C is derived as follows:
( 8 - 1137 ) ##EQU00081## t C = ( B .times. itDepth C < 10 ) ? (
t C ' + 2 ) ( 10 - B .times. itDepth C ) : t C ' * ( 1 ( BitDepth C
- 8 ) ) ##EQU00081.2##
When maxFilterLengthCbCr is equal to 1 and bS is not equal to 2,
maxFilterLengthCbCr is set equal to 0. When maxFilterLengthCbCr is
equal to 3, the following ordered steps apply: [0585] 1. The
variables n1, dpq0c, dpq1c, dpc, dqc and d are derived as
follows:
[0585] n .times. 1 = ( subSampleC == 2 ) ? 1 : 3 ( 8 - 1138 )
##EQU00082## dp .times. 0 .times. c _ = Abs ( p .times. c _ , 2 , 0
- 2 * p .times. c _ , 1 , 0 + p .times. c _ , 0 , 0 ) ( 8 - 1139 )
##EQU00082.2## dp .times. 1 .times. c _ = Abs .function. ( p
.times. c _ , 2 , n .times. 1 - 2 * p .times. c _ , 1 , 0 + p
.times. c _ , 0 , n .times. 1 ) ( 8 - 1140 ) ##EQU00082.3## dq
.times. 0 .times. c _ = Abs .function. ( q .times. c _ , 2 , 0 - 2
* q .times. c _ , 1 , 0 + q .times. c _ , 0 , 0 ) ( 8 - 1141 )
##EQU00082.4## dq .times. 1 .times. c _ = Abs .function. ( q
.times. c _ , 2 , n .times. 1 - 2 * q .times. c _ , 1 , n .times. 1
+ q .times. c _ , 0 , n .times. 1 ) ( 8 - 1142 ) ##EQU00082.5## dp
.times. q .times. 0 .times. c _ = dp .times. 0 .times. c _ + dq
.times. 0 .times. c _ ( 8 - 1143 ) ##EQU00082.6## dpq .times. 1
.times. c _ = dp .times. 1 .times. c _ + dq .times. 1 .times. c _ (
8 - 1144 ) ##EQU00082.7## dp .times. c _ = dp .times. 0 .times. c _
+ dp .times. 1 .times. c _ ( 8 - 1145 ) ##EQU00082.8## dq .times. c
_ = dq .times. 0 .times. c _ + dq .times. 1 .times. c _ ( 8 - 1146
) ##EQU00082.9## d .times. c _ = dpq .times. 0 .times. c _ + dpq
.times. 1 .times. c _ ( 8 - 1147 ) ##EQU00082.10## [0586] 2. [0587]
3. The variables dSam0 and dSam1 are both set equal to 0. [0588] 4.
When d is less than .beta., the following ordered steps apply:
[0589] a. The variable dpq is set equal to 2*dpq0. [0590] b. The
variable dSam0 is derived by invoking the decision process for a
chroma sample as specified in clause 8.8.3.6.8 for the sample
location (xCb+xBl,yCb+yBl) with sample values p.sub.0,0, p.sub.3,0,
q.sub.0,0, and q3,0, the variables dpq, .beta. and t.sub.C as
inputs, and the output is assigned to the decision dSam0. [0591] c.
The variable dpq is set equal to 2*dpq1. [0592] d. The variable
dSam1 is modified as follows: [0593] If edgeType is equal to
EDGE_VER, for the sample location (xCb+xBl,yCb+yBl+n1), the
decision process for a chroma sample as specified in clause
8.8.3.6.8 is invoked with sample values p.sub.0,n1, p.sub.3,n1,
q.sub.0,n1, and q.sub.3,n1, the variables dpq, .beta. and t.sub.C
as inputs, and the output is assigned to the decision dSam1. [0594]
Otherwise (edgeType is equal to EDGE_HOR), for the sample location
(xCb+xBl+n1,yCb+yBl), the decision process for a chroma sample as
specified in clause 8.8.3.6.8 is invoked with sample values
p.sub.0,n1, P.sub.3,n1, q.sub.0,n1 and q.sub.3,n1, the variables
dpq, .beta. and t.sub.C as inputs, and the output is assigned to
the decision dSam1. [0595] 5. The variable maxFilterLengthCbCr is
modified as follows: [0596] If dSam0 is equal to 1 and dSam1 is
equal to 1, maxFilterLengthCbCr is set equal to 3. [0597]
Otherwise, maxFilterLengthCbCr is set equal to 1.
8.8.3.6.4 Filtering Process for Chroma Block Edges
[0598] This process is only invoked when ChromaArrayType is not
equal to 0. Inputs to this process are: [0599] a chroma picture
sample array recPicture, [0600] a chroma location (xCb,yCb)
specifying the top-left sample of the current chroma coding block
relative to the top-left chroma sample of the current picture,
[0601] a chroma location (xBl,yBl) specifying the top-left sample
of the current chroma block relative to the top-left sample of the
current chroma coding block, [0602] a variable edgeType specifying
whether a vertical (EDGE_VER) or a horizontal (EDGE_HOR) edge is
filtered, [0603] a variable maxFilterLengthCbCr containing the
maximum chroma filter length, [0604] 6. [0605] the variable tC.
Output of this process is the modified chroma picture sample array
recPicture. . . . The values p.sub.i and q.sub.i with i=0 . . .
maxFilterLengthCbCr and k=0 . . . maxK are derived as follows:
[0606] If edgeType is equal to EDGE_VER, the following applies:
[0606] q i , k = recPicture .times. [ xCb + xB .times. 1 + i ] [ y
.times. C .times. b + yB .times. 1 + k ] ( 8 - 1150 ) ##EQU00083##
p i , k = recPicture .times. [ xCb + xB .times. 1 - i - 1 ] [ y
.times. C .times. b + yB .times. 1 + k ] ( 8 - 1151 )
##EQU00083.2## [0607] Otherwise (edgeType is equal to EDGE_HOR),
the following applies:
[0607] q i , k = recPicture .times. [ xCb + xB .times. 1 + k ] [ y
.times. C .times. b + yB .times. 1 + i ] ( 8 - 1152 ) ##EQU00084##
p i , k = recPicture .times. [ xCb + xB .times. 1 + k ] [ y .times.
C .times. b + yB .times. 1 - i - 1 ] ( 8 - 1153 )
##EQU00084.2##
Depending on the value of edgeType, the following applies: [0608]
If edgeType is equal to EDGE_VER, for each sample location
(xCb+xBl,yCb+yBl+k), k=0 . . . maxK, the following ordered steps
apply: [0609] 1. The filtering process for a chroma sample as
specified in clause 8.8.3.6.9 is invoked with the variable
maxFilterLengthCbCr, the sample values p.sub.i,k, q.sub.i,k with
i=0 . . . maxFilterLengthCbCr, the locations
(xCb+xBl-i-1,yCb+yBl+k) and (xCb+xBl+i,yCb+yBl+k) with i=0 . . .
maxFilterLengthCbCr-1, and the variable t.sub.C as inputs, and the
filtered sample values p.sub.i' and q.sub.i' with i=0 . . .
maxFilterLengthCbCr-1 as outputs. [0610] 2. The filtered sample
values p.sub.i' and q.sub.i' with i=0 . . . maxFilterLengthCbCr-1
replace the corresponding samples inside the sample array
recPicture as follows:
[0610] recPicture .times. [ xCb + xB .times. 1 + i ] [ y .times. C
.times. b + y .times. B .times. 1 + k ] = q i ' ( 8 - 1154 )
##EQU00085## recPicture .times. [ xCb + xB .times. 1 - i - 1 ] [
yCb + yB .times. 1 + k ] = p i ' ( 8 - 1155 ) ##EQU00085.2## [0611]
Otherwise (edgeType is equal to EDGE_HOR), for each sample location
(xCb+xBl+k,yCb+yBl), k=0 . . . maxK, the following ordered steps
apply: [0612] 1. The filtering process for a chroma sample as
specified in clause 8.8.3.6.9 is invoked with the variable
maxFilterLengthCbCr, the sample values p.sub.i,k, q.sub.i,k, with
i=0 . . . maxFilterLengthCbCr, the locations
(xCb+xBl+k,yCb+yBl-i-1) and (xCb+xBl+k,yCb+yBl+i), and the variable
t.sub.C as inputs, and the filtered sample values p.sub.i' and
q.sub.i' as outputs. [0613] 2. The filtered sample values p.sub.i'
and q.sub.i' replace the corresponding samples inside the sample
array recPicture as follows:
[0613] recPicture .times. [ xCb + xB .times. 1 + k ] [ y .times. C
.times. b + y .times. B .times. 1 + i ] = q i ' ( 8 - 1156 )
##EQU00086## recPicture .times. [ xCb + xB .times. 1 + k ] [ yCb +
yB .times. 1 - i - 1 ] = p i ' ##EQU00086.2##
5.11 Embodiment #11
8.8.3.6.3 Decision Process for Chroma Block Edges
[0614] . . . [[The variables Qp.sub.Q and Qp.sub.P are set equal to
the Qp.sub.Y values of the coding units which include the coding
blocks containing the sample q.sub.0,0 and p.sub.0,0, respectively.
The variable Qp.sub.C is derived as follows:
q .times. P .times. i = Clip .times. 3 .times. ( 0 , 63 , ( ( Q
.times. p Q + Qp P + 1 ) 1 ) + cQpPicOffset ) ( 8 - 1132 )
##EQU00087## Qp C = ChromaOpTable [ cIdx - 1 ] [ qPi ] ( 8 - 1133 )
] ] ##EQU00087.2##
[0615] [0616]
[0616] [0617]
[0617] 5.12 Embodiment #12
8.8.3.6.3 Decision Process for Chroma Block Edges
[0618] . . . [[The variables Qp.sub.Q and Qp.sub.P are set equal to
the Qp.sub.Y values of the coding units which include the coding
blocks containing the sample q.sub.0,0 and p.sub.0,0, respectively.
The variable Qp.sub.C is derived as follows:
q .times. P .times. i = Clip .times. 3 .times. ( 0 , 63 , ( ( Q
.times. p Q + Qp P + 1 ) 1 ) + cQpPicOffset ( 8 - 1132 )
##EQU00088## Qp C = ChromaOpTable [ cIdx - 1 ] [ qPi ] ( 8 - 1133 )
##EQU00088.2## [0619] NOTE--The variable cQpPicOffset provides an
adjustment for the value of pps_cb_qp_offset or pps_cr_qp_offset,
according to whether the filtered chroma component is the Cb or Cr
component. However, to avoid the need to vary the amount of the
adjustment within the picture, the filtering process does not
include an adjustment for the value of slice_cb_qp_offset or
slice_cr_qp_offset nor (when cu_chroma_qp_offset_enabled_flag is
equal to 1) for the value of CuQpOffset.sub.Cb, CuQpOffset.sub.Cr,
or CuQpOffset.sub.CbCr.]]
[0619] 6. Example Implementations of the Disclosed Technology
[0620] FIG. 12 is a block diagram of a video processing apparatus
1200. The apparatus 1200 may be used to implement one or more of
the methods described herein. The apparatus 1200 may be embodied in
a smartphone, tablet, computer, Internet of Things (IoT) receiver,
and so on. The apparatus 1200 may include one or more processors
1202, one or more memories 1204 and video processing hardware 1206.
The processor(s) 1202 may be configured to implement one or more
methods described in the present document. The memory (memories)
1204 may be used for storing data and code used for implementing
the methods and techniques described herein. The video processing
hardware 1206 may be used to implement, in hardware circuitry, some
techniques described in the present document, and may be partly or
completely be a part of the processors 1202 (e.g., graphics
processor core GPU or other signal processing circuitry).
[0621] In the present document, the term "video processing" may
refer to video encoding, video decoding, video compression or video
decompression. For example, video compression algorithms may be
applied during conversion from pixel representation of a video to a
corresponding bitstream representation or vice versa. The bitstream
representation of a current video block may, for example,
correspond to bits that are either co-located or spread in
different places within the bitstream, as is defined by the syntax.
For example, a macroblock may be encoded in terms of transformed
and coded error residual values and also using bits in headers and
other fields in the bitstream.
[0622] It will be appreciated that the disclosed methods and
techniques will benefit video encoder and/or decoder embodiments
incorporated within video processing devices such as smartphones,
laptops, desktops, and similar devices by allowing the use of the
techniques disclosed in the present document.
[0623] FIG. 13 is a flowchart for an example method 1300 of video
processing. The method 1300 includes, at 1310, performing a
conversion between a video unit and a bitstream representation of
the video unit, wherein, during the conversion, a deblocking filter
is used on boundaries of the video unit such that when a chroma
quantization parameter (QP) table is used to derive parameters of
the deblocking filter, processing by the chroma QP table is
performed on individual chroma QP values.
[0624] Some embodiments may be described using the following
clause-based format.
[0625] 1. A method of video processing, comprising:
[0626] performing a conversion between a video unit and a bitstream
representation of the video unit, wherein, during the conversion, a
deblocking filter is used on boundaries of the video unit such that
when a chroma quantization parameter (QP) table is used to derive
parameters of the deblocking filter, processing by the chroma QP
table is performed on individual chroma QP values.
[0627] 2. The method of clause 1, wherein chroma QP offsets are
added to the individual chroma QP values subsequent to the
processing by the chroma QP table.
[0628] 3. The method of any of clauses 1-2, wherein the chroma QP
offsets are added to values outputted by the chroma QP table.
[0629] 4. The method of any of clauses 1-2, wherein the chroma QP
offsets are not considered as input to the chroma QP table.
[0630] 5. The method of clause 2, wherein the chroma QP offsets are
at a picture-level or at a video unit-level.
[0631] 6. A method of video processing, comprising:
[0632] performing a conversion between a video unit and a bitstream
representation of the video unit, wherein, during the conversion, a
deblocking filter is used on boundaries of the video unit such that
chroma QP offsets are used in the deblocking filter, wherein the
chroma QP offsets are at picture/slice/tile/brick/sub picture
level.
[0633] 7. The method of clause 6, wherein the chroma QP offsets
used in the deblocking filter are associated with a coding method
applied on a boundary of the video unit.
[0634] 8. The method of clause 7, wherein the coding method is a
joint coding of chrominance residuals (JCCR) method.
[0635] 9. A method of video processing, comprising:
[0636] performing a conversion between a video unit and a bitstream
representation of the video unit, wherein, during the conversion, a
deblocking filter is used on boundaries of the video unit such that
chroma QP offsets are used in the deblocking filter, wherein
information pertaining to a same luma coding unit is used in the
deblocking filter and for deriving a chroma QP offset.
[0637] 10. The method of clause 9, wherein the same luma coding
unit covers a corresponding luma sample of a center position of the
video unit, wherein the video unit is a chroma coding unit.
[0638] 11. The method of clause 9, wherein a scaling process is
applied to the video unit, and wherein one or more parameters of
the deblocking filter depend at least in part on
quantization/dequantization parameters of the scaling process.
[0639] 12. The method of clause 11, wherein the
quantization/dequantization parameters of the scaling process
include the chroma QP offset.
[0640] 13. The method of any of clauses 9-12, wherein the luma
sample in the video unit is in the P side or Q side.
[0641] 14. The method of clause 13, wherein the information
pertaining to the same luma coding unit depends on a relative
position of the coding unit with respect to the same luma coding
unit.
[0642] 15. A method of video processing, comprising:
[0643] performing a conversion between a video unit and a bitstream
representation of the video unit, wherein, during the conversion, a
deblocking filter is used on boundaries of the video unit such that
chroma QP offsets are used in the deblocking filter, wherein an
indication of enabling usage of the chroma QP offsets is signaled
in the bitstream representation.
[0644] 16. The method of clause 15, wherein the indication is
signaled conditionally in response to detecting one or more
flags.
[0645] 17. The method of clause 16, wherein the one or more flags
are related to a JCCR enabling flag or a chroma QP offset enabling
flag.
[0646] 18. The method of clause 15, wherein the indication is
signaled based on a derivation.
[0647] 19. A method of video processing, comprising:
[0648] performing a conversion between a video unit and a bitstream
representation of the video unit, wherein, during the conversion, a
deblocking filter is used on boundaries of the video unit such that
chroma QP offsets are used in the deblocking filter, wherein the
chroma QP offsets used in the deblocking filter are identical of
whether JCCR coding method is applied on a boundary of the video
unit or a method different from the JCCR coding method is applied
on the boundary of the video unit.
20. A method of video processing, comprising:
[0649] performing a conversion between a video unit and a bitstream
representation of the video unit, wherein, during the conversion, a
deblocking filter is used on boundaries of the video unit such that
chroma QP offsets are used in the deblocking filter, wherein a
boundary strength (BS) of the deblocking filter is calculated
without comparing reference pictures and/or a number of motion
vectors (MVs) associated with the video unit at a P side boundary
with reference pictures and/or a number of motion vectors (MVs)
associated with the video unit at a Q side.
21. The method of clause 20, wherein the deblocking filter is
disabled under one or more conditions.
22. The method of clause 21, wherein the one or more conditions are
associated with: a magnitude of the motion vectors (MVs) or a
threshold value.
[0650] 23. The method of clause 22, wherein the threshold value is
associated with at least one of: i. contents of the video unit, ii.
a message signaled in DPS/SPS/VPS/PPS/APS/picture header/slice
header/tile group header/Largest coding unit (LCU)/Coding unit
(CU)/LCU row/group of LCUs/TU/PU block/Video coding unit, iii. a
position of CU/PU/TU/block/Video coding unit, iv. a coded mode of
blocks with samples along the boundaries, v. a transform matrix
applied to the video units with samples along the boundaries, vi. a
shape or dimension of the video unit, vii. an indication of a color
format, viii. a coding tree structure, ix. a slice/tile group type
and/or picture type, x. a color component, xi. a temporal layer ID,
or xii. a profile/level/tier of a standard.
[0651] 24. The method of clause 20, wherein different QP offsets
are used for TS coded video units and non-TS coded video units.
[0652] 25. The method of clause 20, wherein a QP used in a luma
filtering step is related to a QP used in a scaling process of a
luma block.
[0653] 26. A video decoding apparatus comprising a processor
configured to implement a method recited in one or more of clauses
1 to 25.
[0654] 27. A video encoding apparatus comprising a processor
configured to implement a method recited in one or more of clauses
1 to 25.
[0655] 28. A computer program product having computer code stored
thereon, the code, when executed by a processor, causes the
processor to implement a method recited in any of clauses 1 to
25.
[0656] 29. A method, apparatus or system described in the present
document.
[0657] FIG. 15 is a block diagram that illustrates an example video
coding system 100 that may utilize the techniques of this
disclosure.
[0658] As shown in FIG. 15, video coding system 100 may include a
source device 110 and a destination device 120. Source device 110
generates encoded video data which may be referred to as a video
encoding device. Destination device 120 may decode the encoded
video data generated by source device 110 which may be referred to
as a video decoding device.
[0659] Source device 110 may include a video source 112, a video
encoder 114, and an input/output (I/O) interface 116.
[0660] Video source 112 may include a source such as a video
capture device, an interface to receive video data from a video
content provider, and/or a computer graphics system for generating
video data, or a combination of such sources. The video data may
comprise one or more pictures. Video encoder 114 encodes the video
data from video source 112 to generate a bitstream. The bitstream
may include a sequence of bits that form a coded representation of
the video data. The bitstream may include coded pictures and
associated data. The coded picture is a coded representation of a
picture. The associated data may include sequence parameter sets,
picture parameter sets, and other syntax structures. I/O interface
116 may include a modulator/demodulator (modem) and/or a
transmitter. The encoded video data may be transmitted directly to
destination device 120 via I/O interface 116 through network 130a.
The encoded video data may also be stored onto a storage
medium/server 130b for access by destination device 120.
[0661] Destination device 120 may include an I/O interface 126, a
video decoder 124, and a display device 122.
[0662] I/O interface 126 may include a receiver and/or a modem. I/O
interface 126 may acquire encoded video data from the source device
110 or the storage medium/server 130b. Video decoder 124 may decode
the encoded video data. Display device 122 may display the decoded
video data to a user. Display device 122 may be integrated with the
destination device 120, or may be external to destination device
120 which be configured to interface with an external display
device.
[0663] Video encoder 114 and video decoder 124 may operate
according to a video compression standard, such as the High
Efficiency Video Coding (HEVC) standard, Versatile Video Coding
(VVC) standard and other current and/or further standards.
[0664] FIG. 16 is a block diagram illustrating an example of video
encoder 200, which may be video encoder 114 in the system 100
illustrated in FIG. 15.
[0665] Video encoder 200 may be configured to perform any or all of
the techniques of this disclosure. In the example of FIG. 16, video
encoder 200 includes a plurality of functional components. The
techniques described in this disclosure may be shared among the
various components of video encoder 200. In some examples, a
processor may be configured to perform array or all of the
techniques described in this disclosure.
[0666] The functional components of video encoder 200 may include a
partition unit 201, a predication unit 202 which may include a mode
select unit 203, a motion estimation unit 204, a motion
compensation unit 205 and an intra prediction unit 206, a residual
generation unit 207, a transform unit 208, a quantization unit 209,
an inverse quantization unit 210, an inverse transform unit 211, a
reconstruction unit 212, a buffer 213, and an entropy encoding unit
214.
[0667] In other examples, video encoder 200 may include more,
fewer, or different functional components. In an example,
predication unit 202 may include an intra block copy (IBC) unit.
The IBC unit may perform predication in an IBC mode in which at
least one reference picture is a picture where the current video
block is located.
[0668] Furthermore, some components, such as motion estimation unit
204 and motion compensation unit 205 may be highly integrated, but
are represented in the example of FIG. 5 separately for purposes of
explanation.
[0669] Partition unit 201 may partition a picture into one or more
video blocks. Video encoder 200 and video decoder 300 may support
various video block sizes.
[0670] Mode select unit 203 may select one of the coding modes,
intra or inter, e.g., based on error results, and provide the
resulting intra- or inter-coded block to a residual generation unit
207 to generate residual block data and to a reconstruction unit
212 to reconstruct the encoded block for use as a reference
picture. In some example, Mode select unit 203 may select a
combination of intra and inter predication (CIIP) mode in which the
predication is based on an inter predication signal and an intra
predication signal. Mode select unit 203 may also select a
resolution for a motion vector (e.g., a sub-pixel or integer pixel
precision) for the block in the case of inter-predication.
[0671] To perform inter prediction on a current video block, motion
estimation unit 204 may generate motion information for the current
video block by comparing one or more reference frames from buffer
213 to the current video block. Motion compensation unit 205 may
determine a predicted video block for the current video block based
on the motion information and decoded samples of pictures from
buffer 213 other than the picture associated with the current video
block.
[0672] Motion estimation unit 204 and motion compensation unit 205
may perform different operations for a current video block, for
example, depending on whether the current video block is in an I
slice, a P slice, or a B slice.
[0673] In some examples, motion estimation unit 204 may perform
uni-directional prediction for the current video block, and motion
estimation unit 204 may search reference pictures of list 0 or list
1 for a reference video block for the current video block. Motion
estimation unit 204 may then generate a reference index that
indicates the reference picture in list 0 or list 1 that contains
the reference video block and a motion vector that indicates a
spatial displacement between the current video block and the
reference video block. Motion estimation unit 204 may output the
reference index, a prediction direction indicator, and the motion
vector as the motion information of the current video block. Motion
compensation unit 205 may generate the predicted video block of the
current block based on the reference video block indicated by the
motion information of the current video block.
[0674] In other examples, motion estimation unit 204 may perform
bi-directional prediction for the current video block, motion
estimation unit 204 may search the reference pictures in list 0 for
a reference video block for the current video block and may also
search the reference pictures in list 1 for another reference video
block for the current video block. Motion estimation unit 204 may
then generate reference indexes that indicate the reference
pictures in list 0 and list 1 containing the reference video blocks
and motion vectors that indicate spatial displacements between the
reference video blocks and the current video block. Motion
estimation unit 204 may output the reference indexes and the motion
vectors of the current video block as the motion information of the
current video block. Motion compensation unit 205 may generate the
predicted video block of the current video block based on the
reference video blocks indicated by the motion information of the
current video block.
[0675] In some examples, motion estimation unit 204 may output a
full set of motion information for decoding processing of a
decoder.
[0676] In some examples, motion estimation unit 204 may do not
output a full set of motion information for the current video.
Rather, motion estimation unit 204 may signal the motion
information of the current video block with reference to the motion
information of another video block. For example, motion estimation
unit 204 may determine that the motion information of the current
video block is sufficiently similar to the motion information of a
neighboring video block.
[0677] In one example, motion estimation unit 204 may indicate, in
a syntax structure associated with the current video block, a value
that indicates to the video decoder 300 that the current video
block has the same motion information as the another video
block.
[0678] In another example, motion estimation unit 204 may identify,
in a syntax structure associated with the current video block,
another video block and a motion vector difference (MVD). The
motion vector difference indicates a difference between the motion
vector of the current video block and the motion vector of the
indicated video block. The video decoder 300 may use the motion
vector of the indicated video block and the motion vector
difference to determine the motion vector of the current video
block.
[0679] As discussed above, video encoder 200 may predictively
signal the motion vector. Two examples of predictive signaling
techniques that may be implemented by video encoder 200 include
advanced motion vector predication (AMVP) and merge mode
signaling.
[0680] Intra prediction unit 206 may perform intra prediction on
the current video block. When intra prediction unit 206 performs
intra prediction on the current video block, intra prediction unit
206 may generate prediction data for the current video block based
on decoded samples of other video blocks in the same picture. The
prediction data for the current video block may include a predicted
video block and various syntax elements.
[0681] Residual generation unit 207 may generate residual data for
the current video block by subtracting (e.g., indicated by the
minus sign) the predicted video block(s) of the current video block
from the current video block. The residual data of the current
video block may include residual video blocks that correspond to
different sample components of the samples in the current video
block.
[0682] In other examples, there may be no residual data for the
current video block for the current video block, for example in a
skip mode, and residual generation unit 207 may not perform the
subtracting operation.
[0683] Transform processing unit 208 may generate one or more
transform coefficient video blocks for the current video block by
applying one or more transforms to a residual video block
associated with the current video block.
[0684] After transform processing unit 208 generates a transform
coefficient video block associated with the current video block,
quantization unit 209 may quantize the transform coefficient video
block associated with the current video block based on one or more
quantization parameter (QP) values associated with the current
video block.
[0685] Inverse quantization unit 210 and inverse transform unit 211
may apply inverse quantization and inverse transforms to the
transform coefficient video block, respectively, to reconstruct a
residual video block from the transform coefficient video block.
Reconstruction unit 212 may add the reconstructed residual video
block to corresponding samples from one or more predicted video
blocks generated by the predication unit 202 to produce a
reconstructed video block associated with the current block for
storage in the buffer 213.
[0686] After reconstruction unit 212 reconstructs the video block,
loop filtering operation may be performed reduce video blocking
artifacts in the video block.
[0687] Entropy encoding unit 214 may receive data from other
functional components of the video encoder 200. When entropy
encoding unit 214 receives the data, entropy encoding unit 214 may
perform one or more entropy encoding operations to generate entropy
encoded data and output a bitstream that includes the entropy
encoded data.
[0688] FIG. 17 is a block diagram illustrating an example of video
decoder 300 which may be video decoder 114 in the system 100
illustrated in FIG. 15.
[0689] The video decoder 300 may be configured to perform any or
all of the techniques of this disclosure. In the example of FIG.
17, the video decoder 300 includes a plurality of functional
components. The techniques described in this disclosure may be
shared among the various components of the video decoder 300. In
some examples, a processor may be configured to perform any or all
of the techniques described in this disclosure.
[0690] In the example of FIG. 17, video decoder 300 includes an
entropy decoding unit 301, a motion compensation unit 302, an intra
prediction unit 303, an inverse quantization unit 304, an inverse
transformation unit 305, and a reconstruction unit 306 and a buffer
307. Video decoder 300 may, in some examples, perform a decoding
pass generally reciprocal to the encoding pass described with
respect to video encoder 200 (e.g., FIG. 16).
[0691] Entropy decoding unit 301 may retrieve an encoded bitstream.
The encoded bitstream may include entropy coded video data (e.g.,
encoded blocks of video data). Entropy decoding unit 301 may decode
the entropy coded video data, and from the entropy decoded video
data, motion compensation unit 302 may determine motion information
including motion vectors, motion vector precision, reference
picture list indexes, and other motion information. Motion
compensation unit 302 may, for example, determine such information
by performing the AMVP and merge mode.
[0692] Motion compensation unit 302 may produce motion compensated
blocks, possibly performing interpolation based on interpolation
filters. Identifiers for interpolation filters to be used with
sub-pixel precision may be included in the syntax elements.
[0693] Motion compensation unit 302 may use interpolation filters
as used by video encoder 20 during encoding of the video block to
calculate interpolated values for sub-integer pixels of a reference
block. Motion compensation unit 302 may determine the interpolation
filters used by video encoder 200 according to received syntax
information and use the interpolation filters to produce predictive
blocks.
[0694] Motion compensation unit 302 may uses some of the syntax
information to determine sizes of blocks used to encode frame(s)
and/or slice(s) of the encoded video sequence, partition
information that describes how each macroblock of a picture of the
encoded video sequence is partitioned, modes indicating how each
partition is encoded, one or more reference frames (and reference
frame lists) for each inter-encoded block, and other information to
decode the encoded video sequence.
[0695] Intra prediction unit 303 may use intra prediction modes for
example received in the bitstream to form a prediction block from
spatially adjacent blocks. Inverse quantization unit 303 inverse
quantizes, i.e., de-quantizes, the quantized video block
coefficients provided in the bitstream and decoded by entropy
decoding unit 301. Inverse transform unit 303 applies an inverse
transform.
[0696] Reconstruction unit 306 may sum the residual blocks with the
corresponding prediction blocks generated by motion compensation
unit 202 or intra-prediction unit 303 to form decoded blocks. If
desired, a deblocking filter may also be applied to filter the
decoded blocks in order to remove blockiness artifacts. The decoded
video blocks are then stored in buffer 307, which provides
reference blocks for subsequent motion compensation.
[0697] FIG. 18 is a block diagram showing an example video
processing system 1800 in which various techniques disclosed herein
may be implemented. Various implementations may include some or all
of the components of the system 1800. The system 1800 may include
input 1802 for receiving video content. The video content may be
received in a raw or uncompressed format, e.g., 8 or 10 bit
multi-component pixel values, or may be in a compressed or encoded
format. The input 1802 may represent a network interface, a
peripheral bus interface, or a storage interface. Examples of
network interface include wired interfaces such as Ethernet,
passive optical network (PON), etc. and wireless interfaces such as
Wi-Fi or cellular interfaces.
[0698] The system 1800 may include a coding component 1804 that may
implement the various coding or encoding methods described in the
present document. The coding component 1804 may reduce the average
bitrate of video from the input 1802 to the output of the coding
component 1804 to produce a coded representation of the video. The
coding techniques are therefore sometimes called video compression
or video transcoding techniques. The output of the coding component
1804 may be either stored, or transmitted via a communication
connected, as represented by the component 1806. The stored or
communicated bitstream (or coded) representation of the video
received at the input 1802 may be used by the component 1808 for
generating pixel values or displayable video that is sent to a
display interface 1810. The process of generating user-viewable
video from the bitstream representation is sometimes called video
decompression. Furthermore, while certain video processing
operations are referred to as "coding" operations or tools, it will
be appreciated that the coding tools or operations are used at an
encoder and corresponding decoding tools or operations that reverse
the results of the coding will be performed by a decoder.
[0699] Examples of a peripheral bus interface or a display
interface may include universal serial bus (USB) or high definition
multimedia interface (HDMI) or Display port, and so on. Examples of
storage interfaces include SATA (serial advanced technology
attachment), PCI, IDE interface, and the like. The techniques
described in the present document may be embodied in various
electronic devices such as mobile phones, laptops, smartphones or
other devices that are capable of performing digital data
processing and/or video display.
[0700] FIG. 19 is a flowchart representation of a method for video
processing in accordance with the present technology. The method
1900 includes, at operation 1910, determining, for a conversion
between a chroma block of a video and a bitstream representation of
the video, applicability of a deblocking filter process to at least
some samples at an edge of the chroma block based on a mode of
joint coding of chroma residuals for the chroma block. The method
1900 also includes, at operation 1920, performing the conversion
based on the determining.
[0701] In some embodiments, a value indicating the mode of the
joint coding of chroma residuals is equal to 2. In some
embodiments, the deblocking filter process further uses one or more
quantization parameter offsets at a video unit level, the video
unit comprising a picture, a slice, a tile, a brick, or a
subpicture.
[0702] FIG. 20 is a flowchart representation of a method for video
processing in accordance with the present technology. The method
2000 includes, at operation 2010, determining, for a conversion
between a current block of a video and a bitstream representation
of the video, a chroma quantization parameter used in a deblocking
filtering process applied to at least some samples at an edge of
the current block based on information of a corresponding transform
block of the current block. The method 2000 also includes, at
operation 2020, performing the conversion based on the
determining.
[0703] In some embodiments, the chroma quantization parameter is
used for deblocking samples along a first side of the edge of the
current block, and the chroma quantization parameter is based on a
mode of the transform block that are on the first side. In some
embodiments, the first side is referred to as P-side, the P-side
comprising samples located above the edge in case the edge is a
horizontal boundary or to the left of the edge in case the edge is
a vertical boundary. In some embodiments, the chroma quantization
parameter is used for deblocking samples along a second side of the
edge of the current block, and the chroma quantization parameter is
based on a mode of the transform block that are on the second side.
In some embodiments, the second side is referred to as Q-side, the
Q-side comprising samples located below the edge in case the edge
is a horizontal boundary or to the right of the edge in case the
edge is a vertical boundary.
[0704] In some embodiments, the chroma quantization parameter is
determined based on whether a mode of joint coding of chroma
residuals is applied. In some embodiments, the chroma quantization
parameter is determined based on whether a mode of the joint coding
of chroma residuals is equal to 2.
[0705] FIG. 21 is a flowchart representation of a method for video
processing in accordance with the present technology. The method
2100 includes, at operation 2110, performing a conversion between a
current block of a video and a bitstream representation of the
video. During the conversion, a first chroma quantization parameter
used in a deblocking filtering process applied to at least some
samples along an edge of the current block is based on a second
chroma quantization parameter used in a scaling process and a
quantization parameter offset associated with a bit depth.
[0706] In some embodiments, the first chroma quantization parameter
is equal to the second quantization parameter used in the scaling
process minus the quantization parameter offset associated with the
bit depth. In some embodiments, the first chroma quantization
parameter used for deblocking samples along a first side of the
edge of the current block. In some embodiments, the first side is
referred to as P-side, the P-side comprising samples located above
the edge in case the edge is a horizontal boundary or to the left
of the edge in case the boundary is a vertical boundary. In some
embodiments, the first chroma quantization parameter used for
deblocking samples along a second side of the edge of the current
block. In some embodiments, the second side is referred to as
Q-side, the Q-side comprising samples located below the edge in
case the edge is a horizontal boundary or to the right of the edge
in case the edge is a vertical boundary.
[0707] In some embodiments, the first chroma quantization parameter
is equal to the second quantization parameter for a joint coding of
chroma residuals used in the scaling process minus quantization
parameter offset associated with the bit depth. In some
embodiments, the first chroma quantization parameter is equal to
the second quantization parameter for a chroma Cb component used in
the scaling process minus quantization parameter offset associated
with the bit depth. In some embodiments, the first chroma
quantization parameter is equal to the second quantization
parameter for a chroma Cr component used in the scaling process
minus quantization parameter offset associated with the bit
depth.
[0708] FIG. 22 is a flowchart representation of a method for video
processing in accordance with the present technology. The method
2200 includes, at operation 2210, performing a conversion between a
video comprising one or more coding units and a bitstream
representation of the video. The bitstream representation conforms
to a format rule that specifies that chroma quantization parameters
are included in the bitstream representation at a coding unit level
or a transform unit level according to the format rule.
[0709] In some embodiments, the format rule specifies that the
chroma quantization parameter is included at a coding unit level in
case a size of the coding unit is larger than a virtual pipeline
data unit. In some embodiments, the format rule specifies that the
chroma quantization parameter is included at a transform unit level
in case a size of the coding unit is larger than or equal to a
virtual pipeline data unit. In some embodiments, the format rule
specifies that the chroma quantization parameter is included at a
coding unit level in case a size of the coding unit is larger than
a maximum transform block size. In some embodiments, the format
rule specifies that the chroma quantization parameter is included
at a transform unit level in case a size of the coding unit is
larger than or equal to a maximum transform block size. In some
embodiments, the format rule further specifies that whether a joint
coding of chroma residuals mode is applicable to a first coding
unit of the one or more coding units is indicated at a coding unit
level. In some embodiments, a transform block within the first
coding unit inherits information about whether the joint coding of
chroma residuals mode is applicable at the first coding unit
level.
[0710] FIG. 23 is a flowchart representation of a method for video
processing in accordance with the present technology. The method
2300 includes, at operation 2310, performing a conversion between a
block of a video and a bitstream representation of the video. The
bitstream representation conforms to a format rule specifying that
whether a joint coding of chroma residuals mode is applicable to
the block is indicated at a coding unit level in the bitstream
representation.
[0711] In some embodiments, during the conversion, a transform
block within a coding unit inherits information about whether the
joint coding of chroma residuals mode is applicable at the coding
unit level.
[0712] In some embodiments, the conversion includes encoding the
video into the bitstream representation. In some embodiments, the
conversion includes decoding the bitstream representation into the
video.
[0713] Some embodiments of the disclosed technology include making
a decision or determination to enable a video processing tool or
mode. In an example, when the video processing tool or mode is
enabled, the encoder will use or implement the tool or mode in the
processing of a block of video, but may not necessarily modify the
resulting bitstream based on the usage of the tool or mode. That
is, a conversion from the block of video to the bitstream
representation of the video will use the video processing tool or
mode when it is enabled based on the decision or determination. In
another example, when the video processing tool or mode is enabled,
the decoder will process the bitstream with the knowledge that the
bitstream has been modified based on the video processing tool or
mode. That is, a conversion from the bitstream representation of
the video to the block of video will be performed using the video
processing tool or mode that was enabled based on the decision or
determination.
[0714] Some embodiments of the disclosed technology include making
a decision or determination to disable a video processing tool or
mode. In an example, when the video processing tool or mode is
disabled, the encoder will not use the tool or mode in the
conversion of the block of video to the bitstream representation of
the video. In another example, when the video processing tool or
mode is disabled, the decoder will process the bitstream with the
knowledge that the bitstream has not been modified using the video
processing tool or mode that was enabled based on the decision or
determination.
[0715] The disclosed and other solutions, examples, embodiments,
modules and the functional operations described in this document
can be implemented in digital electronic circuitry, or in computer
software, firmware, or hardware, including the structures disclosed
in this document and their structural equivalents, or in
combinations of one or more of them. The disclosed and other
embodiments can be implemented as one or more computer program
products, i.e., one or more modules of computer program
instructions encoded on a computer readable medium for execution
by, or to control the operation of, data processing apparatus. The
computer readable medium can be a machine-readable storage device,
a machine-readable storage substrate, a memory device, a
composition of matter effecting a machine-readable propagated
signal, or a combination of one or more them. The term "data
processing apparatus" encompasses all apparatus, devices, and
machines for processing data, including by way of example a
programmable processor, a computer, or multiple processors or
computers. The apparatus can include, in addition to hardware, code
that creates an execution environment for the computer program in
question, e.g., code that constitutes processor firmware, a
protocol stack, a database management system, an operating system,
or a combination of one or more of them. A propagated signal is an
artificially generated signal, e.g., a machine-generated
electrical, optical, or electromagnetic signal, that is generated
to encode information for transmission to suitable receiver
apparatus.
[0716] A computer program (also known as a program, software,
software application, script, or code) can be written in any form
of programming language, including compiled or interpreted
languages, and it can be deployed in any form, including as a
stand-alone program or as a module, component, subroutine, or other
unit suitable for use in a computing environment. A computer
program does not necessarily correspond to a file in a file system.
A program can be stored in a portion of a file that holds other
programs or data (e.g., one or more scripts stored in a markup
language document), in a single file dedicated to the program in
question, or in multiple coordinated files (e.g., files that store
one or more modules, sub programs, or portions of code). A computer
program can be deployed to be executed on one computer or on
multiple computers that are located at one site or distributed
across multiple sites and interconnected by a communication
network.
[0717] The processes and logic flows described in this document can
be performed by one or more programmable processors executing one
or more computer programs to perform functions by operating on
input data and generating output. The processes and logic flows can
also be performed by, and apparatus can also be implemented as,
special purpose logic circuitry, e.g., an FPGA (field programmable
gate array) or an ASIC (application specific integrated
circuit).
[0718] Processors suitable for the execution of a computer program
include, by way of example, both general and special purpose
microprocessors, and any one or more processors of any kind of
digital computer. Generally, a processor will receive instructions
and data from a read only memory or a random-access memory or both.
The essential elements of a computer are a processor for performing
instructions and one or more memory devices for storing
instructions and data. Generally, a computer will also include, or
be operatively coupled to receive data from or transfer data to, or
both, one or more mass storage devices for storing data, e.g.,
magnetic, magneto optical disks, or optical disks. However, a
computer need not have such devices. Computer readable media
suitable for storing computer program instructions and data include
all forms of non-volatile memory, media and memory devices,
including by way of example semiconductor memory devices, e.g.,
EPROM, EEPROM, and flash memory devices; magnetic disks, e.g.,
internal hard disks or removable disks; magneto optical disks; and
CD ROM and DVD-ROM disks. The processor and the memory can be
supplemented by, or incorporated in, special purpose logic
circuitry.
[0719] While this patent document contains many specifics, these
should not be construed as limitations on the scope of any subject
matter or of what may be claimed, but rather as descriptions of
features that may be specific to particular embodiments of
particular techniques. Certain features that are described in this
patent document in the context of separate embodiments can also be
implemented in combination in a single embodiment. Conversely,
various features that are described in the context of a single
embodiment can also be implemented in multiple embodiments
separately or in any suitable subcombination. Moreover, although
features may be described above as acting in certain combinations
and even initially claimed as such, one or more features from a
claimed combination can in some cases be excised from the
combination, and the claimed combination may be directed to a
subcombination or variation of a subcombination.
[0720] Similarly, while operations are depicted in the drawings in
a particular order, this should not be understood as requiring that
such operations be performed in the particular order shown or in
sequential order, or that all illustrated operations be performed,
to achieve desirable results. Moreover, the separation of various
system components in the embodiments described in this patent
document should not be understood as requiring such separation in
all embodiments.
[0721] Only a few implementations and examples are described and
other implementations, enhancements and variations can be made
based on what is described and illustrated in this patent
document.
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