U.S. patent application number 16/603991 was filed with the patent office on 2020-04-16 for 360-degree video coding using face continuities.
This patent application is currently assigned to VID SCALE, INC.. The applicant listed for this patent is VID SCALE, INC.. Invention is credited to Philippe Hanhart, Yuwen He, Yan Ye.
Application Number | 20200120359 16/603991 |
Document ID | / |
Family ID | 62067880 |
Filed Date | 2020-04-16 |
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United States Patent
Application |
20200120359 |
Kind Code |
A1 |
Hanhart; Philippe ; et
al. |
April 16, 2020 |
360-DEGREE VIDEO CODING USING FACE CONTINUITIES
Abstract
A coding device (e.g., that may be or may include encoder and/or
decoder) may receive a frame-packed picture of 380-degree video.
The coding device may identify a face in the frame-packed picture
that the current block belongs to. The coding device may determine
that a current block is located at a boundary of the face that the
current block belongs to. The coding device may identify multiple
spherical neighboring blocks of the current block. The coding
device may identify a cross-face boundary neighboring block. The
coding device may identify a block in the frame-packed picture that
corresponds to the cross-face boundary neighboring block. The
coding device may determine whether to use the identified block to
code the current block based on availability of the identified
block. The coding device may code the current block based on the
determination to use the identified block.
Inventors: |
Hanhart; Philippe; (La
Conversion, CH) ; He; Yuwen; (San Diego, CA) ;
Ye; Yan; (San Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
VID SCALE, INC. |
Wilmington |
DE |
US |
|
|
Assignee: |
VID SCALE, INC.
Wilmington
DE
|
Family ID: |
62067880 |
Appl. No.: |
16/603991 |
Filed: |
April 10, 2018 |
PCT Filed: |
April 10, 2018 |
PCT NO: |
PCT/US2018/026828 |
371 Date: |
October 9, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62484218 |
Apr 11, 2017 |
|
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62525880 |
Jun 28, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04N 19/105 20141101;
H04N 19/597 20141101; H04N 19/52 20141101; H04N 19/61 20141101;
H04N 19/167 20141101; H04N 19/593 20141101; H04N 19/174 20141101;
H04N 19/176 20141101; H04N 19/117 20141101 |
International
Class: |
H04N 19/597 20060101
H04N019/597; H04N 19/105 20060101 H04N019/105; H04N 19/117 20060101
H04N019/117; H04N 19/174 20060101 H04N019/174; H04N 19/593 20060101
H04N019/593; H04N 19/61 20060101 H04N019/61 |
Claims
1-20. (canceled)
21. A method of decoding a 360-degree video comprising: receiving a
frame-packed picture in a bitstream; receiving a cross boundary
loop filter indicator that indicates whether loop filtering is
disabled across a boundary in the frame-packed picture; based on
the cross boundary loop filter indicator indicating that loop
filtering is disabled across the boundary in the frame-packed
picture, determining a location of the boundary in the frame-packed
picture where loop filtering is disabled based on the cross
boundary loop filter indicator; and disabling loop filtering across
the determined location of the boundary in the frame-packed
picture.
22. The method of claim 21, wherein the boundary in the
frame-packed picture comprises one or more of a face boundary, a
tile boundary, or a slice boundary.
23. The method of claim 21, wherein the cross boundary loop filter
indicator comprises a cross boundary loop filter flag that
indicates whether loop filtering is disabled across the boundary in
the frame-packed picture.
24. The method of claim 21, wherein the cross boundary loop filter
indicator is received in a picture parameter set (PPS).
25. The method of claim 21, wherein determining the location of the
boundary in the frame-packed picture where loop filtering is
disabled based on the cross boundary loop filter indicator further
comprises: identifying a plurality of boundaries in the
frame-packed picture; and determining, from the plurality of
identified boundaries in the frame-packed picture, the location of
the boundary where loop filtering is disabled based on the cross
boundary loop filter indicator.
26. The method of claim 25, further comprising: receiving a
plurality of indications that indicate corresponding locations of
the plurality of boundaries in the frame-packed picture, wherein
the plurality of boundaries in the frame-packed picture are
identified based on the plurality of indications.
27. The method of claim 21, wherein the cross boundary loop filter
indicator comprises one or more of a sample adaptive offset (SAO)
filter, a deblocking filter, or an adaptive loop filter (ALF).
28. The method of claim 21, wherein the method comprises:
identifying a plurality of boundaries in the frame-packed picture;
determining, from the plurality of identified boundaries in the
frame-packed picture, the location of the boundary where loop
filtering is enabled based on the cross boundary loop filter
indicator; and applying loop filtering across the determined
location of the boundary where loop filtering is enabled.
29. The method of claim 21, wherein the cross boundary loop filter
indicator indicates that loop filtering is disabled across a
discontinuous boundary of in the frame-packed picture and indicates
that loop filtering is enabled across a continuous boundary of in
the frame-packed picture.
30. The method of claim 21, wherein the frame-packed picture
comprises a horizontal boundary and a vertical boundary associated
with the frame-packed picture.
31. A coding device for a 360-degree video comprising: a memory;
and a processor configured to: receive a frame-packed picture in a
bitstream; receive a cross boundary loop filter indicator that
indicates whether loop filtering is disabled across a boundary in
the frame-packed picture; based on the cross boundary loop filter
indicator indicating that loop filtering is disabled across the
boundary in the frame-packed picture, determine a location of the
boundary in the frame-packed picture where loop filtering is
disabled based on the cross boundary loop filter indicator; and
disable loop filtering across the determined location of the
boundary in the frame-packed picture.
32. The coding device of claim 31, wherein the boundary in the
frame-packed picture comprises one or more a face boundary, a tile
boundary, or a slice boundary.
33. The coding device of claim 31, wherein the cross boundary loop
filter indicator comprises a cross boundary loop filter flag that
indicates whether loop filtering is disabled across the boundary in
the frame-packed picture.
34. The coding device of claim 31, wherein the cross boundary loop
filter indicator is received in a picture parameter set (PPS).
35. The coding device of claim 31, wherein to determine the
location of the boundary in the frame-packed picture where loop
filtering is disabled based on the cross boundary loop filter
indicator, the processor is further configured to: identify a
plurality of boundaries in the frame-packed picture; and determine,
from the plurality of identified boundaries in the frame-packed
picture, the location of the boundary where loop filtering is
disabled based on the cross boundary loop filter indicator.
36. The coding device of claim 35, the processor is further
configured to: receive a plurality of indications that indicate
corresponding locations of the plurality of boundaries in the
frame-packed picture, wherein the plurality of boundaries in the
frame-packed picture are identified based on the plurality of
indications.
37. The coding device of claim 31, wherein the cross boundary loop
filter indicator comprises one or more of a sample adaptive offset
(SAO) filter, a deblocking filter, or an adaptive loop filter
(ALF).
38. The coding device of claim 31, wherein the processor is
configured to: identify a plurality of boundaries in the
frame-packed picture; determine, from the plurality of identified
boundaries in the frame-packed picture, the location of the
boundary where loop filtering is enabled based on the cross
boundary loop filter indicator; and apply loop filtering across the
determined location of the boundary where loop filtering is
enabled.
39. The coding device of claim 31, wherein the cross boundary loop
filter indicator indicates that loop filtering is disabled across a
discontinuous boundary of in the frame-packed picture and indicates
that loop filtering is enabled across a continuous boundary of in
the frame-packed picture.
40. The coding device of claim 31, wherein the frame-packed picture
comprises a horizontal boundary and a vertical boundary associated
with the frame-packed picture.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application Ser. No. 62/484,218 filed Apr. 11, 2017 and U.S.
Provisional Application Ser. No. 62/525,880 filed Jun. 28, 2017,
the contents of which are incorporated by reference herein.
BACKGROUND
[0002] Virtual reality (VR) started to go into our daily lives. For
example, VR has many application in areas including, but not
limited to, healthcare, education, social networking, industry
design/training, game, movie, shopping, and/or entertainment. VR
may enhance a viewer's experience, for example, by creating a
virtual environment surrounding the viewer and generating a true
sense of "being there" for the viewer. A user's experience may rely
on, for example, providing a full real feeling in the VR
environment. For example, the VR system may support interactions
through posture, gesture, eye gaze, and/or voice. The VR system may
provide haptic feedback to the user to allow the user to interact
with objects in the VR world in a natural way. VR systems may use
360-degree video to provide the users, for example, the capability
to view the scene from 360-degree angles in the horizontal
direction and/or 180-degree angles in the vertical direction.
SUMMARY
[0003] A coding device (e.g., a device that may be or may include
an encoder and/or a decoder) may receive a frame-packed picture of
360-degree video. The frame-packed picture may include multiple
faces and a current block. The coding device may identify a face in
the frame-packed picture that the current block belongs to. The
coding device may determine that the current block is located at an
exiting boundary of the face that the current block belongs to. For
example, the coding device may determine that the current block is
located at the exiting boundary of the face that the current block
belongs according to the coding order of the frame-packed picture.
The exiting boundary of the face that the current block belongs to
may be located in the same direction of the coding order that is
relative to the current block.
[0004] The frame-packed picture may be coded in a coding order. In
examples, the coding order may have left to right direction
relative to a current block associated with the frame-packed
picture. In examples, the coding order may have top to bottom
direction relative to the current block. In examples, the coding
order may have left to right and top to bottom direction relative
to the current block. In examples, if the coding order has left to
right direction relative to the current block, the exiting boundary
of the face may be located on the right side (e.g., rightmost side
of the face that the current block belongs to). In examples, if the
coding order has top to bottom direction relative to the current
block, the exiting boundary of the face may be located on the
bottom side (e.g., bottommost side of the face that the current
block belongs to). In examples, if the coding order has left to
right and top to bottom direction relative to the current block,
the exiting boundary of the face may be located at the right and
bottom side (e.g., rightmost and bottommost side of the face that
the current block belongs to).
[0005] Upon determining that the current block is located at the
exiting boundary of the face that the current block belongs to, the
coding device may use a cross-face boundary neighboring block
located on a face that shares a boundary with the exiting boundary
of the face that the current block belongs to for coding the
current block. For example, the coding device may identify multiple
spherical neighboring blocks of the current block. For example, the
coding device may identify multiple spherical neighboring blocks of
the current block based on the spherical characteristics of the
360-degree video. The coding device may identify a cross-face
boundary neighboring block associated with the current block. For
example, the coding device may identify the cross-face boundary
neighboring block among the identified multiple spherical
neighboring blocks of the current block. In examples, the
cross-face boundary neighboring block may be located on a face that
shares a boundary with the exiting boundary of the face that the
current block belongs to. In examples, the cross-face boundary
neighboring block may be located on an opposite side of the face
boundary that the current block belongs to and is located in the
same direction of the coding order relative to the current
block.
[0006] The coding device may determine whether to use the
cross-face boundary neighboring block to code the current block.
For example, a block in the frame-packed picture that corresponds
to the cross-face boundary neighboring block may be identified. The
block in the frame-packed picture that corresponds to the
cross-face boundary neighboring block may be identified based on
the frame-packing information of the 360-degree video. The coding
device may determine whether to use the identified block in the
frame-packed picture that corresponds to the cross-face boundary
neighboring block to code the current block based on availability
of the identified block in the frame-packed picture. For example,
the availability of the identified block in the frame-packed
picture may be determined based on whether the identified block has
been coded. The coding device may code the current block based on
the determination to use the identified block in the frame-packed
picture and may code the current block using the identified and
available block that corresponds to the cross-face boundary
neighboring block.
[0007] As used herein, a 360-degree video may include or may be a
spherical video, an omnidirectional video, a virtual reality (VR)
video, a panorama video, an immersive video (e.g., a light field
video that may include 6 degree of freedom), a point cloud video,
and/or the like.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1A depicts an example sphere sampling in longitudes
(.PHI.) and latitudes (.theta.).
[0009] FIG. 1B depicts an example sphere being projected to 2D
plane using a equirectangular projection (ERP).
[0010] FIG. 1C depicts an example picture produced using ERP.
[0011] FIG. 2A depicts an example 3D geometry structure in a
cubemap projection (CMP).
[0012] FIG. 2B depicts an example 2D planar with 4.times.3 frame
packing and six faces.
[0013] FIG. 2C depicts an example picture produced using CMP.
[0014] FIG. 3 depicts an example workflow for a 360-degree video
system.
[0015] FIG. 4A depicts an example picture generated by the
repetitive padding boundaries using ERP.
[0016] FIG. 4B depicts an example picture generated by the
repetitive padding boundaries using CMP.
[0017] FIG. 5A depicts an example geometry padding for ERP showing
padding geometry.
[0018] FIG. 5B depicts an example geometry padding for ERP showing
padded ERP picture.
[0019] FIG. 6A depicts an example geometry padding process for CMP
showing padding geometry.
[0020] FIG. 6B depicts an example geometry padding process for CMP
showing padded CMP faces.
[0021] FIG. 7 is an example diagram of block-based video
encoder.
[0022] FIG. 8 is an example diagram of block-based video
decoder.
[0023] FIG. 9 depicts example reference samples used in high
efficiency video coding (HEVC) intra prediction.
[0024] FIG. 10 depicts an example indication of intra prediction
directions in HEVC.
[0025] FIG. 11A depicts an example projection of left reference
samples to extend the top reference row to the left.
[0026] FIG. 11B depicts an example projection of above reference
samples to extend the left reference column upward.
[0027] FIGS. 12A-D depict example boundary prediction filtering for
(A) intra mode 2; (B) intra mode 34; (C) intra modes 3-6; and (D)
intra modes 30-33.
[0028] FIG. 13 depicts example spatial neighbors used for most
probable modes in the HEVC intra angular process.
[0029] FIG. 14 depicts an example location of the samples used for
derivation of .alpha. and .beta. in cross-component linear model
prediction.
[0030] FIG. 15 depicts an example inter prediction with one motion
vector.
[0031] FIG. 16 depicts an example padding for reference samples
outside the picture boundary.
[0032] FIG. 17 depicts an example spatial neighbors used for merge
candidates in the HEVC merge process.
[0033] FIG. 18A depicts an example 3D representation of CMP.
[0034] FIG. 18B depicts an example 3.times.2 frame packing
configuration of CMP.
[0035] FIG. 19 depicts an example reconstructed samples used for
predicting the current block in intra and inter coding.
[0036] FIGS. 20A-C depict example spatial neighbors at the (A)
right face boundary; (B) bottom face boundary; and (C) bottom right
face boundary.
[0037] FIGS. 21A-C depict example availability of reconstructed
samples at the (A) right face boundary; (B) bottom face boundary;
and (C) bottom right face boundary.
[0038] FIGS. 22A-B depict example additional intra prediction modes
at (A) right face boundary; and (B) bottom face boundary.
[0039] FIGS. 23A-D depict example additional intra prediction modes
at the (A-B) right face boundaries; and (C-D) bottom face
boundaries.
[0040] FIGS. 24A-D depict example bi-directional intra predictions
at the (A-B) right face boundaries; and (C-D) bottom face
boundaries.
[0041] FIGS. 25A-H depict example boundary prediction filtering at
right face boundary for: (A) intra mode 2; (B) intra modes 3-6; (C)
intra modes 7-9; (D) intra mode 10; (E) intra modes 11-17; (F)
intra mode 18; (G) intra modes 19-21; and (H) intra mode 22.
[0042] FIGS. 26A-H depict example boundary prediction filtering at
bottom face boundary for: (A) intra mode 14; (B) intra modes 15-17;
(C) intra mode 18; (D) intra modes 19-25; (E) intra mode 26; (F)
intra modes 27-29; (G) intra modes 30-33; and (H) intra mode
34.
[0043] FIGS. 27A-C depict example location of the samples used for
cross-component linear model prediction at the (A) right face
boundary; (B) bottom face boundary; and (C) bottom right face
boundary.
[0044] FIG. 28 illustrates example equations for calculating linear
model parameters (e.g., equations (38), (41), (43) and (44)).
[0045] FIGS. 29A-B depicts examples of block processing order for
CMP 3.times.2 packing configuration: (A) raster scan order; and (B)
face scan order.
[0046] FIG. 30 depicts an example coding tree unit (CTU) and block
partitioning.
[0047] FIG. 31 depicts an example 3.times.2 packing configuration.
The dashed lines may represent the CTU boundaries, and the arrows
may represent the shared boundary between two faces.
[0048] FIG. 32 depicts an example 3.times.2 packing configuration
as described herein. The dashed lines may represent the CTU
boundaries, and the arrows may represent the shared boundary
between two faces.
[0049] FIG. 33A is a system diagram illustrating an example
communications system in which one or more disclosed embodiments
may be implemented.
[0050] FIG. 33B is a system diagram illustrating an example
wireless transmit/receive unit (WTRU) that may be used within the
communications system illustrated in FIG. 33A according to an
embodiment.
[0051] FIG. 33C is a system diagram illustrating an example radio
access network (RAN) and an example core network (CN) that may be
used within the communications system illustrated in FIG. 33A
according to an embodiment.
[0052] FIG. 33D is a system diagram illustrating a further example
RAN and a further example CN that may be used within the
communications system illustrated in FIG. 33A according to an
embodiment.
DETAILED DESCRIPTION
[0053] A detailed description of illustrative embodiments will now
be described with reference to the various Figures. Although this
description provides a detailed example of possible
implementations, it should be noted that the details are intended
to be exemplary and in no way limit the scope of the
application.
[0054] VR system and/or 360-degree video may be for media
consumption beyond, for example, Ultra High Definition (UHD)
service. Improving the quality of 360-degree video in VR and/or
standardizing the processing chain for client's interoperability
may have been focused by one or more groups. In examples, an ad hoc
group may set up in ISO/IEC/MPEG to work on the requirements and/or
technologies for omnidirectional media application format. In
examples, an ad hoc group, may have performed exploration
experiments for 360-degree 3D video application. The ad hoc group
may have tested for 360-degree video (e.g., omnidirectional video)
based system and/or multi-view based system. A joint video
exploration team (JVET) from MPEG and ITU-T, which is exploring
technologies for next generation video coding standard, issued a
call for test sequences including VR. Ad hoc group (AHG8) was
established and the mandates of the AHG8 group are to work out the
common test conditions, test sequence formats, and evaluation
criteria for 360-degree video coding. AHG8 may study the effect on
compression when different projection methods are applied, as well
as the conversion software. One or more companies were willing to
provide some 360-degree videos as test sequences to develop coding
technologies for 360-degree video. A reference software 360Lib is
established by JVET to perform projection format conversion and
measure objective 360-degree video quality metric in order to
conduct experiments following a set of common test conditions and
evaluation procedures. Considering the interest in 360-degree video
coding, JVET agreed to include 360-degree video in the preliminary
joint call for evidence on video compression with capability beyond
HEVC.
[0055] Quality and/or user's experience of one or more aspects in
the VR processing chain, including capturing, processing, display,
and/or applications may be improved. For example, on the capturing
side, VR system may use one or more cameras to capture a scene from
one or more different views (e.g., 6.about.12 views). The different
views may be stitched together to form 360-degree video in high
resolution (e.g., 4K or 8K). For example, on the client or user
side, the VR system may include a computation platform, a head
mounted display (HMD), and/or a head tracking sensor. The
computation platform may receive and/or decode the 360-degree video
and may generate a viewport for display. Two pictures, one for each
eye, may be rendered for the viewport. The two pictures may be
displayed in the HMD for stereo viewing. Lens may be used to
magnify the image displayed in the HMD for better viewing. The head
tracking sensor may keep (e.g., constantly keep) track of the
viewer's head orientation and may feed the orientation information
to the system to display the viewport picture for that orientation.
A VR system may provide a touch device (e.g., specialized touch
device) for the viewer, e.g., to interact with objects in the
virtual world. In examples, a VR system may be driven by a
workstation with GPU support. In examples, a VR system may use a
smartphone as a computation platform, a HMD display, and/or a head
tracking sensor. The spatial HMD resolution may be 2160.times.1200.
Refresh rate may be 90 Hz, and the field of view (FOV) may be 110
degree. The sampling rate for a head tracking sensor may be 1000
Hz, which may capture fast (e.g., very fast) movement. An example
of VR system may use a smartphone as computation platform and may
include of lens and/or cardboard. 360-degree video streaming
service may exist.
[0056] Quality of experience, such as interactivity and/or haptic
feedback, may be improved in the VR systems. For example, a HMD may
be too big and/or may not convenient to wear. The resolution
provided by the HMDs (e.g., 2160.times.1200 for stereoscopic views)
may not be sufficient, and may cause dizziness and/or discomfort
for a user. The resolution may be increased. A feeling from vision
in VR environment may be combined with a feedback (e.g., force
feedback) in the real world and may enhance VR experience. VR
roller coaster may be an example such combined application.
[0057] 360-degree video delivery may represent the 360-degree
information, e.g., using a sphere geometry structure. For example,
the synchronized one or more views captured by the one or more
cameras may be stitched on a sphere as an integral structure. The
sphere information may be projected to 2D planar surface with a
geometry conversion process. For example, an equirectangular
projection (ERP) and/or a cubemap projection (CMP) may be used to
illustrate the projection format.
[0058] ERP may map the latitude and/or longitude coordinates of a
spherical globe onto (e.g., directly onto) horizontal and/or
vertical coordinates of a grid. FIG. 1A depicts an example of
sphere sampling in longitudes (.PHI.) and latitudes (.theta.). FIG.
1B depicts an example of sphere being projected to 2D plane using,
for example ERP. FIG. 1C depicts an example of projective picture
with ERP. The longitude .PHI. in the range [-.pi., .pi.] may be
yaw, and latitude .theta. in the range [-.pi./2, .pi./2] may be
pitch in aviation. .pi. may be the ratio of a circle's
circumference to its diameter. In FIGS. 1A-B, (x, y, z) may
represent a point's coordinates in 3D space, and (ue, ve) may
represent the coordinate of one point in 2D plane. ERP may be
represented mathematically as shown in Equations 1 and/or 2:
ue=(.phi./(2*.pi.)+0.5)*W (1)
ve=(0.5-.theta./.pi.)*H (2)
where W and H may be the width and height of the 2D planar picture.
As shown in FIG. 1A, the point P, the cross point between longitude
L4 and latitude A1 on the sphere, may be mapped to a unique point q
(e.g., FIG. 1B) in the 2D plane using the Equation (1) and (2). The
point q in 2D plane may be projected back to the point P on the
sphere via inverse projection. The field of view (FOV) in FIG. 1B
may show an example that the FOV in sphere may be mapped to 2D
plane with the view angle along X axis being about 110 degrees.
[0059] 360-degree video may be mapped to a 2D video using ERP. For
example, the 360-degree video may be encoded with video codecs,
such as H.264 and/or HEVC. The encoded 360-degree video may be
delivered to the client. At the client side, the equirectangular
video may be decoded. The equirectangular video may be rendered,
e.g., based on user's viewport by projecting and/or displaying the
portion belonging to FOV in the equirectangular picture onto the
HMD. Spherical video may be transformed to 2D planar picture for
encoding with ERP. The characteristic of equirectangular 2D picture
may differ from a 2D picture (e.g., rectilinear video).
[0060] FIG. 1C depicts an example picture produced using ERP. As
shown in FIG. 1C, the top and/or bottom portions of the ERP picture
(e.g., North Pole and/or South Pole, respectively) may be stretched
compared to, for example, the middle portion of the picture (e.g.,
equator). The stretching of the top and/or bottom portions of the
ERP picture may indicate that the spherical sampling density may be
uneven for ERP format. The motion field, which may describe the
temporal correlation among neighboring ERP pictures, may become
complicated than 2D video.
[0061] A video codec (e.g., MPEG-2, H.264, or HEVC) may use
translational model to describe motion field. The video codec may
not represent (e.g., not efficiently represent) shape varying
movement in equirectangular projected 2D planar pictures. As shown
in FIG. 1C, areas closer to the poles (e.g., North and/or South
Pole) in ERP may be less interesting for a viewer and/or a content
provider. For example, the viewer may not focus on the top and/or
bottom regions for a long duration. Based on the warping effect,
the stretched areas may become a large portion of the 2D plane
after ERP, and compressing these regions may take a lot of bits.
Equirectangular picture coding may be improved by applying
pre-processing, such as smoothing to the pole areas to reduce the
bandwidth to code the pole areas. One or more geometric projections
may be used to map 360-degree video onto multiple faces. For
example, the one or more geometric projections may include, but not
limited to, cubemap, equal-area, cylinder, pyramid, and/or
octahedron.
[0062] The cubemap projection (CMP) may be in a compression
friendly format. The CMP includes 6 faces. For example, the CMP may
include 6 square faces. The faces may be a planar square. FIG. 2A
depicts an example 3D geometry structure in CMP. If the radius of
the tangent sphere is 1 (e.g., FIG. 2A), the lateral length of one
or more faces (e.g., square faces) of CMP may be 2. FIG. 2B depicts
an example 2D packing method to place 6 faces into a rectangular
picture, which may be used for encoding and/or delivery. FIG. 2C
depicts an example picture produced using CMP. The shaded parts
shown in FIG. 2C may be padded regions to fill in the rectangular
picture. For a face, the picture may look the same as 2D picture.
The boundary of a face may not be continuous. For example, the
straight line crossing two neighboring faces may bend and/or may
become multiple line segments (e.g., two line segments) at the
boundary of the two faces. The motion at the face boundary may be
discontinuous.
[0063] One or more objective quality metrics have been proposed for
the coding efficiency of one or more different geometry
projections. For example, peak signal-to-noise ratio (PSNR)
measurements may include spherical PSNR (S-PSNR) and viewport PSNR.
In S-PSNR, the distortion may be measured with mean square error
(MSE) computed over a set of pre-defined samples (e.g., which may
be evenly distributed on the sphere). The latitude based PSNR
(L-PSNR) may be used. L-PSNR may consider the viewer's viewing
behavior by weighting one or more samples based on the sample's
latitude. The weight may be derived by tracking the view angle of
viewers when the viewers view the training sequences. The weight
may be larger if it is viewed frequently. From the statistics, the
weight around the Equator may be larger. For example, the weight
around the Equator may be larger than the weight near the Pole(s)
as interesting content may be located around the Equator. For the
viewport PSNR, a viewport may be rendered and the PSNR may be
computed on the rendered viewport. A portion of the sphere may be
considered, e.g., for the distortion measurement. Average viewport
PSNR may be computed over multiple viewports that cover different
portions of the sphere. S-PSNR may consider a number of samples.
For example S-PSNR may consider samples that may be evenly
distributed on the sphere. The weighted to spherically uniform PSNR
(WS-PSNR) may be used. WS-PSNR may calculate PSNR using one or more
(e.g., all) samples available on the 2D projection plane. For one
or more positions on the 2D projection plane, the distortion may be
weighted by the spherical area covered by that sample position.
WS-PSNR may be computed, e.g., directly in the projection plane.
Different weights may be derived for the different projection
formats. Craster parabolic projection (CPP) may be used to project
the 360-degree image and/or may compute PSNR on the projected
image. This approach may be CPP-PSNR.
[0064] Equirectangular format may be supported with the 360-degree
cameras and/or stitching procedure. Encoding a 360-degree video in
cubemap geometry may use conversion of equirectangular format to
cubemap format. Equirectangular may have relationship with the
cubemap. In FIG. 2A, there are six faces (e.g., PX, NX, PY, NY, PZ,
and NZ), and three axes (e.g., X, Y, and Z) going from the center
of sphere (e.g., O) to the center of a face. "P" may stand for
positive, and "N" may stand for negative. PX may be the direction
along positive X axis from the center of sphere, and NX may be the
reverse direction of PX. Similar notion may be used PY, NY, PZ, and
NZ. The six faces (e.g., PX, NX, PY, NY, PZ, and NZ) may correspond
to the front, back, top, bottom, left, and right faces,
respectively. The faces may be indexed from 0 to 5 (e.g., PX (0),
NX (1), PY (2), NY (3), PZ (4), and NZ (5)). Ps (X_s, Y_s, Z_s) may
be a point on the sphere with a radius being 1. Ps may be
represented in yaw .PHI. and pitch .theta. as follows:
X_s=cos(.theta.)cos(.PHI.) (3)
Y_s=sin(.theta.) (4)
Z_s=-cos(.theta.)sin(.PHI.) (5)
Pf may be a point on the cube when extending the line from the
sphere center to Ps, and Pf may be on face NZ. The coordinates of
Pf, (X_f, Y_f, Z_f), may be calculated as:
X_f=X_s/|Z_s| (6)
Y_f=Y_s/|Z_s| (7)
Z_f=-1 (8)
where |x| may be the absolute value of variable x. The coordinates
of Pf, (uc, vc), in the 2D plane of face NZ may be calculated
as:
uc=W*(1-X_f)/2 (9)
vc=H*(1-Y_f)/2 (10)
[0065] Using one or more equations (3) to (10), there may be a
relationship between the coordinates (uc, vc) in cubemap on a
particular face and the coordinates (.PHI., .theta.) on the sphere.
The relationship between equirectangular point (ue, ye) and the
point (.PHI., .theta.) on the sphere may be known from Equations
(1) and/or (2). There may be a relationship between equirectangular
geometry and cubemap geometry. The geometry mapping from cubemap to
equirectangular may be expressed. For example, the point (uc, vc)
may be given on a face on a cubemap. The output (ue, ve) on the
equirectangular plane may be calculated. For example, the
coordinates of 3D point P_f on the face may be calculated with (uc,
vc) based on the Equations (9) and (10). The coordinates of 3D
point P_s on the sphere may be calculated with P_f based on the
Equations (6), (7), and (8). The (.PHI., .theta.) on the sphere may
be calculated with P_s based on the Equations (3), (4) and (5). The
coordinates of the point (ue, ye) on the equirectangular picture
may be calculated from (.PHI., .theta.) based on the Equations (1)
and (2).
[0066] A 360-degree video may be represented in a 2D picture. For
example, a 360-degree video may be presented in a 2D picture using
cubemap. The six faces of the cubemap may be packed into a
rectangular area. This may be frame packing. The frame packed
pictures may be treated (e.g., coded) as a 2D picture. Different
frame packing configuration(s) may be used (e.g., 3.times.2 and/or
4.times.3 packing configuration). In 3.times.2 configuration, the
six cubemap faces may be packed into 2 rows, with 3 faces in one
row. In 4.times.3 configuration, the 4 faces (e.g., PX, NZ, NX, and
PZ) may be packed into one row (e.g., the center row), and the
faces PY and NY may be packed (e.g., packed separately) into two
different rows (e.g., the top and bottom rows). FIG. 20 depicts an
example of 4.times.3 frame packing that corresponds to the
equirectangular picture in FIG. 1C.
[0067] A 360-degree video in equirectangular format may be input
and may be converted into a cubemap format. For a (e.g., each)
sample position (uc, vc) in cubemap format, the corresponding
coordinates (ue, ve) in equirectangular format may be calculated.
If the calculated coordinates (ue, ve) in equirectangular are not
at an integer sample position, an interpolation filter may be used.
For example, the interpolation filter may be used to obtain a
sample value at the fractional position using samples from the
neighboring integer positions.
[0068] FIG. 3 depicts an example work flow for a 360-degree video
system. The work flow may include a 360-degree video capture using
one or more cameras (e.g., covering the whole sphere space). The
videos may be stitched together in a geometry structure (e.g.,
using an equirectangular geometry structure). The equirectangular
geometry structure may be converted to another geometry structure
(e.g., cubemap or other projection formats) for encoding (e.g.,
encoding with video codecs). The coded video may be delivered to
the client, for example via dynamic streaming or broadcasting. The
video may be decoded. For example, the video may be decoded at the
receiver. The decompressed frame may be unpacked to display
geometry (e.g., equirectangular). The geometry may be used for
rendering (e.g., via viewport projection according to a user's
viewing angle).
[0069] Chroma components may be subsampled, e.g., to a smaller
resolution. For example, chroma components may be subsampled to a
smaller resolution than that of a luma component. Chroma
subsampling may reduce the amount of video data used for encoding
and may save bandwidth and/or computing power and may do so without
affecting (e.g., significantly affecting) video quality. With a
4:2:0 chroma format, both of the chroma components may be
subsampled to be 1/4 of the luma resolution (e.g., 1/2 horizontally
and 1/2 vertically). After chroma subsampling, the chroma sampling
grid may be different from the luma sampling grid. In FIG. 3,
throughout the processing flow, the 360-degree video being
processed at each stage may be in a chroma format where the chroma
components may have been subsampled.
[0070] A video codec(s) may be designed considering 2D video
captured on a plane. When motion compensated prediction uses one or
more samples outside of a reference picture's boundary, padding may
be performed by copying the sample values from the picture
boundaries. For example, repetitive padding may be performed by
copying the sample values from the picture boundaries. FIGS. 4A-B
depict examples of extended pictures generated by the repetitive
padding for ERP (e.g., FIG. 4A) and CMP (e.g., FIG. 4B). In FIGS.
4A-B, the original picture may be within the dotted box, and
extended boundary may be outside of the dotted box. A 360-degree
video may include video information on the whole sphere and may
have a cyclic property. When considering the cyclic property of the
360-degree video, the reference pictures of the 360-degree video
may not have boundaries, as the information that the picture of the
360-degree video includes may be wrapped around a sphere. The
cyclic property may be maintained for one or more different
projection formats or which frame packing is used to represent the
360-degree video on a 2D plane. Geometry padding may be used for
360-degree video coding. For example, geometry padding may be used
for the 360-degree video coding by padding the samples and/or by
considering the 3D geometry structure represented in 360-degree
video.
[0071] Geometry padding for ERP may be defined on the sphere with
longitude and/or latitude. For example, given a point (u, v) to be
padded (e.g., outside of the ERP picture), the point (u', v') used
to derive the padding sample may be calculated as follows:
if ( u < 0 or u .gtoreq. W ) and ( 0 .ltoreq. v < H ) , u ' =
u % W , v ' = v ; ( 11 ) if ( v < 0 ) , v ' = - v - 1 , u ' = (
u + w 2 ) % W ; ( 12 ) if ( v .gtoreq. H ) , v ' = 2 * H - 1 - v ,
u ' = ( u + w 2 ) % W ; ( 13 ) ##EQU00001##
where W and H may be the width and height of the ERP picture. FIG.
5A depicts an example geometry padding process for ERP. For padding
outside of the left boundary of the picture, that is, the samples
at A, B, and C in FIG. 5A, the samples may be padded with the
corresponding samples at A', B', and C', which are located inside
the right boundary of the picture. For padding outside of the right
boundary of the picture (e.g., the samples at D, E, and F in FIG.
5A), the samples may be padded with the corresponding samples at
D', E', and F', which are located inside the left boundary of the
picture. For samples located outside of the top boundary, that is,
the samples at G, H, I, and J in FIG. 5A, the samples are padded
with the corresponding samples at G', H', I', and J', which are
located inside the top boundary of the picture with an offset of
half the width. For samples located outside of the bottom boundary
of the picture (e.g., the samples at K, L, M, and N in FIG. 5A),
the samples may be padded with the corresponding samples at K', L',
M', and N', which are located inside the bottom boundary of the
picture with an offset of half the width. FIG. 5B depicts an
example extended ERP picture using geometry padding. The geometry
padding shown in FIGS. 5A-B may provide meaningful samples and/or
improve continuity of neighboring samples for areas outside of the
ERP picture boundaries.
[0072] If the coded picture is in CMP format, a face of CMP may be
extended by using geometry padding through projecting the samples
of the neighboring faces onto the extended area of the current
face. FIG. 6A depicts an example of how the geometry padding may be
performed for a given CMP face in 3D geometry. In FIG. 6A, point P
may be on face F1 and may be outside of face F1's boundaries. Point
P may be padded. Point O may be the center of the sphere. R may be
the left boundary point closest to P and may be inside face F1
Point Q may be the projection point of point P on face F2 from the
center point O. Geometry padding may use the sample value at point
Q to fill the sample value at point P (e.g., rather than using
sample value at point R to fill the sample value at point P). FIG.
6B depicts an example extended faces with geometry padding for the
CMP 3.times.2 picture. The geometry padding shown in FIGS. 6A-B may
provide meaningful samples for areas outside of the CMP face
boundaries.
[0073] FIG. 7 illustrates an example block-based hybrid video
encoding system 600. The input video signal 602 may be processed
block by block. Extended block sizes (e.g., a coding unit or CU)
may be used (e.g., in HEVC) to compress high resolution (e.g.,
1080p and/or beyond) video signals. A CU may have up to 64.times.64
pixels (e.g., in HEVC). A CU may be partitioned into prediction
units or PUs, for which separate predictions may be applied. For an
input video block (e.g., a macroblock (MB) or CU), spatial
prediction 660 or temporal prediction 662 may be performed. Spatial
prediction (e.g., intra prediction) may use pixels from already
coded neighboring blocks in the same video picture and/or slice to
predict a current video block. Spatial prediction may reduce
spatial redundancy inherent in the video signal. Temporal
prediction (e.g., inter prediction or motion compensated
prediction) may use pixels from already coded video pictures to
predict a current video block. Temporal prediction may reduce
temporal redundancy inherent in the video signal. A temporal
prediction signal for a given video block may be signaled by a
motion vector that indicates the amount and/or direction of motion
between the current block and its reference block. If multiple
reference pictures are supported (e.g., in H.264/AVC or HEVC), the
reference picture index of a video block may be signaled to a
decoder. The reference index may be used to identify from which
reference picture in a reference picture store 664 the temporal
prediction signal may come.
[0074] After spatial and/or temporal prediction, a mode decision
680 in the encoder may select a prediction mode, for example based
on a rate-distortion optimization. The prediction block may be
subtracted from the current video block at 616. Prediction
residuals may be de-correlated using a transform module 604 and a
quantization module 606 to achieve a target bit-rate. The quantized
residual coefficients may be inverse quantized at 610 and inverse
transformed at 612 to form reconstructed residuals. The
reconstructed residuals may be added back to the prediction block
at 626 to form a reconstructed video block. An in-loop filter such
as a de-blocking filter and/or an adaptive loop filter may be
applied to the reconstructed video block at 666 before it is put in
the reference picture store 664. Reference pictures in the
reference picture store 664 may be used to code future video
blocks. An output video bit-stream 620 may be formed. Coding mode
(e.g., inter or intra), prediction mode information, motion
information, and/or quantized residual coefficients may be sent to
an entropy coding unit 608 to be compressed and packed to form the
bit-stream 620.
[0075] FIG. 8 illustrates an example block-based hybrid video
decoder. The decoder in FIG. 8 may correspond to the encoder in
FIG. 7. A video bit-stream 202 may be received, unpacked, and/or
entropy decoded at an entropy decoding unit 208. Coding mode and/or
prediction information may be sent to a spatial prediction unit 260
(e.g., if intra coded) and/or to a temporal prediction unit 262
(e.g., if inter coded). A prediction block may be formed the
spatial prediction unit 260 and/or temporal prediction unit 262.
Residual transform coefficients may be sent to an inverse
quantization unit 210 and an inverse transform unit 212 to
reconstruct a residual block. The prediction block and residual
block may be added at 226. The reconstructed block may go through
in-loop filtering 266 and may be stored in a reference picture
store 264. Reconstructed videos in the reference picture store 264
may be used to drive a display device and/or to predict future
video blocks.
[0076] A video codec(s), such as H.264 and HEVC, may be used to
code 2D planar rectilinear video(s). Video coding may exploit
spatial and/or temporal correlation(s), e.g., to remove information
redundancies. Various prediction techniques such as intra
prediction and inter prediction may be applied during video coding.
Intra prediction may predict a sample value with its neighboring
reconstructed samples. FIG. 9 depicts an example reference samples
that may be used to intra-predict a current transform unit (TU).
The current TU described herein may be a current block, and the two
terms may be used interchangeably. As described herein, the
reference samples may include reconstructed samples located above
or to the left of the current TU.
[0077] One or more intra prediction modes may be selected. For
example, HEVC may specify 35 intra prediction modes that include
planar (0), DC (1), and angular predictions (2.about.34), as shown
in FIG. 10. The planar prediction may generate a first order
approximation for the current block, e.g., using the top and/or
left reconstructed samples. The top right and bottom left sample
values may be copied along the right column and bottom row,
respectively (e.g., because of the raster scan order). A vertical
predictor may be formed for one or more positions within the block,
e.g., using a weighted average of the corresponding top and bottom
samples. A horizontal predictor may be formed using the
corresponding left and right samples. The final predictor may be
formed, e.g., by averaging the vertical and horizontal predictors.
The bottom right sample value may be extrapolated as the average of
the top right and bottom left sample values. The right column
(e.g., bottom row) may be extrapolated using the top right and
bottom right samples (e.g., bottom left and bottom right
samples).
[0078] The angular predictions may be designed to predict the
directional textures. For example, in HEVC, the intra angular
prediction process may be performed by extrapolating sample values
from the reconstructed reference samples utilizing a given
direction. One or more (e.g., all) sample locations within the
current block may be projected to a reference row or column (e.g.,
depending on the angular mode). If the projected pixel locations
have negative indexes, the reference row may be extended to the
left by projecting the left reference column for vertical
prediction, whereas the reference column may be extended upward by
projecting the top reference row for horizontal prediction. FIGS.
11A-B depict example projection for left reference samples (e.g.,
FIG. 11A) and above reference samples (e.g., FIG. 11B). The bold
arrow in FIGS. 11A-B may represent the prediction direction and the
thin arrows may represent the reference sample projection. FIG. 11A
depicts an example process for extending the top reference row
using samples from the left reference column. The predicted samples
may be filtered at the block boundaries to reduce blocking
artifacts (e.g., the intra prediction block has been generated).
For vertical intra mode (e.g., in HEVC), the left-most column of
the prediction samples s.sub.i,j may be adjusted using the left
reference column R.sub.i,j as follows:
s.sub.1,j=s.sub.1,j+(R.sub.0,j-R.sub.0,0) j=1 . . . N (14)
[0079] For horizontal intra mode, the top-most row of the
prediction samples may be adjusted using a similar process. FIGS.
12A-D depict examples of boundary prediction filtering for other
angular modes. For example, FIG. 12A depicts an example boundary
prediction filtering for intra mode 2. For example, FIG. 12B
depicts an example boundary prediction filtering for intra mode 34.
For example, FIG. 12C depicts an example boundary prediction
filtering for intra mode 3-6. For example, FIG. 12D depicts an
example boundary prediction filtering for intra mode 30-33. An
appropriate intra prediction mode may be selected at the encoder
side by minimizing the distortion between prediction generated by
one or more intra prediction modes and original samples. Most
probable mode (MPM) may be used for intra coding (e.g., to encode
the intra prediction mode efficiently). The MPM may reuse the intra
angular mode of spatial neighboring PUs. For example, the MPM may
reuse the intra angular mode of spatial neighboring PUs so that it
may not code the intra angular mode for current PU.
[0080] FIG. 13 depicts an example spatial neighbors (e.g., bottom
left (BL), left (L), above right (AR), top (A), above left (AL))
used for IPM candidate derivation. The selected MPM candidate index
may be coded. The MPM candidate list may be constructed at the
decoder side in the same way as the encoder side. The entry with
the signaled MPM candidate index may be used as the intra angular
mode of current PU. RGB to YUV color conversion may be performed,
e.g., to reduce the correlation between the different channels. A
correlation between the luma and chroma channels may exist. The
cross-component linear model prediction may exploit this
correlation to predict the chroma channels from the luma channels
using a liner model to predict the chroma sample values, p.sub.i,j,
from the downsampled reconstructed luma sample values, L.sub.i,j',
as follows (e.g., assuming a chroma block of N.times.N samples and
following the same notation as in FIG. 9):
p.sub.i,j=.alpha.L.sub.i,j'+.beta. (15)
[0081] The downsampled luma samples may be computed as follows:
L i , j ' = L 2 i - 2 , 2 j - 1 + 2 L 2 i - 1 , 2 j - 1 + L 2 i , 2
j - 1 + L 2 i - 2 , 2 j + 2 L 2 i - 1 , 2 j + L 2 i , 2 j 8 ( 16 )
##EQU00002##
[0082] The parameters of the linear model may be derived by
minimizing the regression error between the top and left
neighboring reconstructed samples. The parameters of the linear
model may be computed as follows:
.alpha. = 2 N [ i = 1 N ( L i , 0 ' C i , 0 ) + j = 1 N ( L 0 , j '
C 0 , j ) ] - ( i = 1 N L i , 0 ' + j = 1 N L 0 , j ' ) ( i = 1 N C
i , 0 + j = 1 N C 0 , j ) 2 N [ i = 1 N ( L i , 0 ' L i , 0 ' ) + j
= 1 N ( L 0 , j ' L 0 , j ' ) ] - ( i = 1 N L i , 0 ' + j = 1 N L 0
, j ' ) ( i = 1 N L i , 0 ' + j = 1 N L 0 , j ' ) ( 17 ) .beta. = (
i = 1 N C i , 0 + j = 1 N C 0 , j ) - .alpha. ( i = 1 N L i , 0 ' +
j = 1 N L 0 , j ' ) 2 N ( 18 ) ##EQU00003##
[0083] FIG. 14 depicts an example location of the top and left
neighboring reconstructed samples used for the derivation of
.alpha. and .beta.. FIG. 15 depicts an example inter prediction
with a motion vector (MV). The block B0' and B1' in the reference
picture may be the reference block of block B0 and B1,
respectively. The reference block B0' may be partially outside the
picture boundary. The padding process (e.g., in HEVC/H.264) may be
configured to fill unknown samples outside the picture boundary.
FIG. 16 depicts an example padding for reference samples outside
the picture boundary (e.g., Block B0') in HEVC/H.264. The Block B0'
may have 4 parts, e.g., P0, P1, P2, and P3. Part P0, P1, and P2 may
be outside the picture boundary and may be filled with padding
process. Part P0 may be filled with the top-left sample of the
picture. Part P1 may be filled with vertical padding using the
topmost row of the picture. Part P2 may be filled with horizontal
padding using the leftmost column of the picture. Motion vector
prediction and merge mode may be used for inter coding to encode
the motion vector information. The motion vector prediction may use
the motion vectors from its neighboring PUs or temporal collocated
PU as current MV's predictor. The encoder and/or the decoder may
form a motion vector predictor candidate list, e.g., in the same
manner. The index of the selected MV predictor from the candidate
list may be coded and signaled to the decoder. The decoder may
construct a MV predictor list, and the entry with the signaled
index may be used as the predictor of current PU's MV. The merge
mode may reuse the MV information of spatial and temporal
neighboring PUs, so that it may not code the motion vectors for
current PU. The encoder and/or the decoder may form a motion vector
merge candidate list, e.g., in the same manner. FIG. 17 depicts an
example spatial neighbors (e.g., bottom left, left, above right,
above, above left) used for merge candidate derivation. The
selected merge candidate index may be coded. The merge candidate
list may be constructed at a decoder side, e.g., in the same way as
at an encoder. The entry with the signaled merge candidate index
may be used as the MV of current PU.
[0084] A frame packed 360-degree video may have different
characteristics than the 2D video. The 360-degree video may include
360-degree information of the environment surrounding a viewer. The
360-degree information may indicate that the 360-degree video has
an intrinsic circular symmetry. The 2D video does not have this
symmetry characteristic. A video codec(s) may have been designed
for a 2D video and may not consider the symmetric feature of the
360-degree video. For example, the codec(s) may process (e.g.,
code) the video in a coding order. For example, the codec(s) may
process the video signal block-by-block using a coding order, such
as a raster scan order, that codes the block from top to bottom
and/or from left to right. The information for coding the current
block may be inferred from blocks located above and/or on the left
of the current block.
[0085] For 360-degree video, a neighboring block in the frame
packed picture may not be the relevant one, e.g., to code the
current block. Blocks that are neighbors of the current block in
the frame packed picture may be frame packed neighbors. Blocks that
are neighbors of the current block in the 3D geometry may be as
face neighbors or spherical neighboring blocks. FIGS. 18A-B depict
examples of CMP. FIG. 18A depicts an example 3D representation of
CMP. FIG. 18B depicts an example 3.times.2 frame packing
configuration of CMP. In FIGS. 18A-B, block A may be the frame
packed neighbor located above block C. Considering the 3D geometry,
block D may be the correct face neighbor (e.g., or spherical
neighboring block) located above block A. An additional face
neighbor block in 360-degree video coding may be used. For example,
when the current block is at the right and/or bottom face boundary
associated with a face of the frame-packed picture, the right
and/or bottom face neighbor block may be used. The right and/or
bottom face neighbor block may be located in the face that is on
the other side (e.g., on the opposite side or cross-face) of the
boundary. For example, the right and/or bottom face neighboring
block may share boundary located at the right and/or bottom face
boundary of the face that the current block belongs to. The face
arrangement and/or scan processing order (e.g., raster scan order)
may be used to determine which blocks may be used to code the
current block as described herein. In the example depicted in FIG.
18B, block B may be the right face neighbor with respect to block
A. If the block B is the right face neighbor with respect to block
A, the right face neighbor may match the right frame packed
neighbor. If the block is scanned from left to right (e.g., a
raster scan having the scan order moving from left to right), block
B may not be coded when coding block A, and the right face neighbor
may not available (e.g., may not be coded yet). When encoding block
E, its right face neighbor (e.g., block F using the intrinsic
spherical characteristics of 360-degree video), may have been coded
and may be used to code (e.g., predict) block E. When encoding
block G, its below face neighbor (e.g., block H using the intrinsic
spherical characteristics of 360-degree video) may have been coded
and may be used to code (e.g., predict) block G. In FIGS. 18A-B, a
block located at the face boundary in one of the hatched areas
(e.g., FIG. 18B) may use its right and/or below face neighbor
block(s) in the coding (e.g., prediction) process of the current
block, as their right and/or bottom neighbors have already been
coded (e.g., available), e.g., considering the spherical
characteristic(s) of 360-degree video. The right and/or bottom face
neighbor blocks may be used as reference blocks.
[0086] For example, the left (L), above (A), above right (AR),
above left (AL), and/or below left (BL) neighbors may be used to
infer information (e.g., because of the scan order, such as raster
scan processing) in 2D video coding (e.g., as shown in FIG. 13 and
FIG. 17). With 360-degree video, if the current block is at the
right face boundary, the right (R) and below right (BR) face
neighbor blocks may be used for inferring attributes (e.g., for
deriving the list of MPMs in intra prediction) for deriving motion
vector candidates in motion vector prediction and/or merge mode. If
the current block is at the bottom face boundary, the below (B) and
below right (BR) face neighbor blocks may be used for inferring
attribute(s). One or more additional spatial candidates may be used
for inferring attribute(s) from neighboring blocks.
[0087] For example, reconstructed samples located above and/or on
the left of the current block may be used (e.g., because of the
raster scan processing) in 2D video coding for predicting the
current block (e.g., as shown in FIG. 9). With 360-degree video, if
the neighboring reconstructed samples are located outside of the
face that the current block belongs to, the samples may be
extrapolated, e.g., using geometry padding. For example, if a block
is at the right face boundary, samples R.sub.N+1,0 . . . R.sub.2N,0
may be obtained using geometry padding. The reconstructed samples
located on the right side of the block (e.g., R.sub.N+1,0 . . .
R.sub.N+1,2N shown in FIG. 19) may be used. FIG. 19 depicts example
reconstructed samples used for prediction the current block in
intra and inter coding. When a block is at the bottom face
boundary, samples located on the bottom side of the block (e.g.,
R.sub.0,N+1 . . . R.sub.2N,N+1) may be used. As described herein,
reconstructed samples (e.g., additional and/or more meaningful
reconstructed samples) may be used in different prediction methods
(e.g., DC, planar, and/or angular modes in intra prediction,
cross-component linear model prediction, boundary prediction
filtering, and/or in-loop filtering).
[0088] 360-degree video coding may use spatial neighbors and
reconstructed samples for intra prediction and/or inter prediction.
A block described herein may include a current block or a sub-block
and may be used interchangeably. If a block is on the right (e.g.,
or bottom) face boundary, its right and below right (e.g., or below
and below right) face neighbor blocks may be considered as a
candidate(s) for the different procedure(s) that infer attributes
from spatial neighbors (e.g., for deriving the MPM in the intra
angular process, for deriving the merge mode in inter prediction,
for motion vector prediction and/or the like). The blocks outside
of the current face may be obtained from the neighboring face(s).
The position of spatial candidates at face boundaries may be
described herein.
[0089] For intra and/or inter prediction, if a block (e.g., current
block) is on the right (e.g., or bottom) face boundary, the
reconstructed samples from its right and below right (e.g., or
below and below right) face neighbor blocks may be used for coding
(e.g., predicting) the current block. The reconstructed samples may
be outside of the current face and may be obtained, e.g., using
geometry padding. The position of reconstructed samples at face
boundaries may be identified as described herein.
[0090] For intra prediction, if a block is on the right (e.g., or
bottom) face boundary, the reconstructed samples from its right and
below right (e.g., or below and below right) face neighbor blocks
may be used for deriving the reference samples. If a block is on
the right (e.g., or bottom) face boundary, one or more additional
horizontal (e.g., or vertical) angular prediction modes may be
defined. The reference samples derivation process and one or more
additional angular modes at face boundaries may be described
herein.
[0091] For intra angular prediction, if a block is on the right
(e.g., or bottom) face boundary, the boundary filtering may be
applied at the block right (e.g., or bottom) boundary. For example,
the boundary filtering may be applied at the block right (e.g.,
bottom) boundary to reduce the discontinuity that may appear at the
intersection between interpolated and reconstructed samples. The
boundary prediction filtering at face boundaries may be described
herein.
[0092] In 2D video coding, the top, right, bottom, and/or left
picture boundaries may not be filtered, e.g., during the in-loop
filtering process. For deblocking, a sample(s) outside of the
boundaries (e.g., top, right, bottom, and/or left) may not exist.
For 360-degree video coding, the top, right, bottom, and/or left
boundaries of a face may be connected to another face boundary. For
example, 360-degree video coding, the top, right, bottom, and/or
left boundaries of a face may be connected to another face boundary
because of the intrinsic circular characteristic of the 360-degree
video. In-loop filtering may be applied across one or more (e.g.,
all) face boundaries. The in-loop filtering process at face
boundaries may be described herein.
[0093] For cross-component linear model prediction, if a block is
on the right (e.g., or bottom) face boundary, the reconstructed
samples from its right (e.g., or below) face neighbor blocks may be
used for estimating the parameters of the linear model. The
reconstructed samples may be outside of the current face and may be
obtained, e.g., using geometry padding. The position of
reconstructed samples at face boundaries, downsampling of the
reconstructed luma samples, and/or derivation of the linear model
parameters may be described herein.
[0094] One or more faces may be processed (e.g., processed
sequentially) by using a scan order (e.g., raster scan order)
within a face. With a face scan order, the availability of face
neighbor blocks may be increased. The face scan order is described
herein.
[0095] For CMP and/or related cube-based geometries, one or more
faces may be packed using a configuration described herein. For
example, the one or more faces may be packed, e.g., having a
3.times.2 packing configuration. The 3.times.2 packing
configuration described herein may maximize the availability of
face neighbor blocks.
[0096] A coding device (e.g., a device that may be or may include
an encoder and/or a decoder) may use one or more additional
neighboring blocks, e.g., based on a position of a current block
inside a geometry face. For example, a coding device may use one or
more additional neighboring blocks based on the position of the
current block inside of the geometry face to increase a number of
candidates that infer information from neighboring block(s). A
coding device may use MPM in intra prediction, motion estimation in
inter prediction, and/or merge mode in inter prediction to infer
information from the neighboring block(s).
[0097] In examples, a coding device (e.g., a device that may be or
may include an encoder and/or a decoder) may receive a frame-packed
picture coded in a coding order. The current block may be located
at an exiting boundary of the face in the frame-packed picture that
the current block belongs to. For example, the coding device may
determine that the current block is located at the exiting boundary
of the face that the current block belongs according to the coding
order of the frame-packed picture. The exiting boundary of the face
that the current block belongs to may be located in the same
direction of the coding order relative to the current block.
[0098] In examples, the coding block may have left to right
direction relative to the current block. If the coding block has
left to right direction relative to the current block, the exiting
boundary of the face in the frame-packed picture that the current
block belongs to may be located at the right face boundary (e.g.,
rightmost face boundary) that the current block belongs to (e.g.,
that may be in the same direction as the coding order). In
examples, the coding block may have top to bottom direction
relative to the current block. If the coding block has top to
bottom direction relative to the current block, the exiting
boundary of the face in the frame-packed picture that the current
block belongs to may be located at the bottom face boundary (e.g.,
bottommost face boundary) that the current block belongs to (e.g.,
that may be in the same direction as the coding order). In
examples, the coding block may have left to right and top to bottom
direction relative to the current block. If the coding block has
left to right and top to bottom direction relative to the current
block, the exiting boundary of the face in the frame-packed picture
that the current block belongs to may be located at the right and
bottom face boundary (e.g., rightmost and bottommost face boundary)
that the current block belongs to (e.g., that may be in the same
direction as the coding order).
[0099] If the coding device determines that the current block is
located at an exiting boundary of the face that the current block
belongs to (e.g., the rightmost and/or bottommost face boundary
that the current block belongs to), the coding device may identify
one or more (e.g., multiple) spherical neighboring blocks of the
current block. For example, the coding device may identify the
spherical neighboring block(s) of the current block based on the
spherical characteristics of the 360-degree video.
[0100] The coding device may identify a cross-face boundary
neighboring block located on a face (e.g., another face) among the
identified spherical neighboring blocks. The face that the
cross-face boundary neighboring block belongs to may share the
boundary (e.g., right and/or bottom face boundary) of the face that
the current block belongs to. For example, the cross-face boundary
neighboring block may be located outside of the current block and
may be located across the face that the current block belongs to
and/or in an opposite side of the face boundary from the current
block. The cross-face boundary neighboring block may be located in
the same direction of the coding order relative to the current
block. For example, the cross-face boundary neighboring block may
be the right (R) block, below (B) block, and/or below right (BR)
block of the current block.
[0101] In examples, if the current block is located at the right
boundary (e.g., rightmost boundary) of the face that the current
block belongs to, the coding device may determine whether the
identified block that corresponds to the cross-face neighboring
block (e.g., right (R) block and/or below right (BR) block) may be
used as candidate(s) (e.g., additional candidate(s)), as depicted
on FIG. 20A.
[0102] FIGS. 20A-C depict example spatial neighbors at the right
face boundary (e.g., FIG. 20A), bottom face boundary (e.g., FIG.
20B), and bottom right face boundary (e.g., FIG. 20C) of the face
that the current block belongs to. Block(s) depicted using a
hatched pattern in FIGS. 20A-C may be located outside of the
current face. If the current block is at the bottom face boundary,
the below (B) and/or below right (BR) (e.g., already coded
neighboring blocks) may be used as candidates (e.g., additional
candidates), as depicted on FIG. 20B, e.g., to predict the current
block. The current block located at the bottom face boundary may
follow similar approach as described herein for the right face
boundary. If the current block is at the bottom right face
boundary, the right, below, and/or below right (e.g., already coded
neighboring blocks) may be used as candidates (e.g., additional
candidates), as depicted on FIG. 20C, e.g., to predict the current
block. The current block located at the bottom right face boundary
may follow similar approach as described herein for the right face
boundary. If a neighboring block position is outside of the current
face, the corresponding block may be obtained from the
corresponding neighboring face (e.g., by mapping sample position
for deriving a spatial neighboring block as described herein).
[0103] Upon identifying the cross-face boundary neighboring block,
the coding device may identify a block in the frame-packed picture
that corresponds to the cross-face neighboring block. For example,
the coding device may identify a block in the frame-packed picture
that corresponds to the cross-face neighboring block based on
frame-packing information of the 360-degree video.
[0104] The coding device may determine whether to use the
identified block in the frame-packed picture that corresponds to
the cross-face neighboring block to code the current block. For
example, the coding device may determine whether to use the
identified block that corresponds to the cross-face neighboring
block to code the current block, e.g., based on the availability of
the identified block in the frame-packed picture. The identified
block in the frame-packed picture may be considered available if
the identified block has been coded. The coding device may
determine whether the identified block that corresponds to the
cross-face neighboring block (e.g., right and/or below right
block(s)) has been coded and/or available to code the current
block. If the coding device determines that the identified block
that corresponds to the cross-face neighboring block (e.g., right
and/or below right block(s)) are available (e.g., already been
coded), the coding device may use the identified block that
corresponds to the cross-face neighboring block.
[0105] The coding device may determine not to use the identified
block that corresponds to the cross-face neighboring block. In
examples, the coding device may determine that the identified block
that corresponds to the cross-face neighboring block has not been
coded and/or unavailable to code the current block. In examples,
the coding device may determine that the current block is located
within a face that the current block belongs to. In examples, the
coding device may determine that the current block is located at an
entering boundary of the face that the current belongs to. The
entering boundary of the face that the current block belongs to may
be located according to the coding order relative to the
frame-packed picture. If the coding device determines not to use
the identified block that corresponds to the cross-face neighboring
block (e.g., when the cross-face neighboring block is not available
and/or has not been coded, the current block is located within a
face, or the current block is located at an entering boundary of a
face that the current block belongs to), the coding device may use
one or more spherical neighboring block(s) that has been coded to
code the current block. A spherical neighboring block(s) described
herein may include a neighboring block of a frame-packed or a
neighboring block of the 3D geometry (e.g., that have been already
coded). For example, the coding device may use at least one of left
(L), above (A), and/or above left blocks as the one or more
spherical neighboring block(s) to code (e.g., predict) the current
block. In examples, the coding device may use geometry padding to
code (e.g., predict) the current block.
[0106] A coding device may use one or more additional blocks (e.g.,
associated with an identified block that corresponds to a
cross-face neighboring block described herein) to increase the
number of available samples associated with the one or more
additional block to predict the current block (e.g., intra
prediction). For example, the coding device may use one or more
additional reconstructed samples, e.g., based on the position of
the current block inside a geometry face. For example, the coding
device may use one or more reconstructed samples (e.g., additional
reconstructed samples) associated with an identified block that
corresponds to a cross-face neighboring block described herein
and/or shown in FIG. 19.
[0107] In examples, the coding device may not use one or more
(e.g., all) reconstructed samples (e.g., additional reconstructed
samples as described herein). For example, if the coding device
determines that a current block is within a face and/or if the
current block is located at the face boundary and the current block
is located in the opposite direction of the coding order relative
to the current block (e.g., at the top face boundary and/or at the
left face boundary), the coding device may use one or more
reconstructed samples depicted in FIG. 9. For example, the coding
device may use one or more reconstructed samples that are available
(e.g., coded). The one or more available reconstructed samples may
be located in the left and/or above neighboring block(s) of the
current block (e.g., spatial neighboring block(s)). One or more
samples located at the right and/or bottom neighboring block of the
current block may not be available (e.g., may not have been coded
and/or reconstructed). If one or more reconstructed samples are
outside of the current block (e.g., current block associated with
the current face), the coding device may obtain one or more
reconstructed samples, e.g., using geometry padding.
[0108] As described herein, a coding device may determine to use
one or more samples from the identified block that corresponds to
the cross-face neighboring block for coding the current block. In
examples, if the coding device determines that the current block is
located at the right face boundary of a face associated with a
frame-packed picture, the coding device may use one or more
reconstructed samples located on the right side of the current
block (e.g., R.sub.N+1,0 . . . R.sub.N+1,2N) (e.g., in addition to
the one or more reconstructed samples associated with a block(s)
located on the left and/or above the current block (e.g., R.sub.0,0
. . . R.sub.0,2N and/or R.sub.0,0 . . . R.sub.N,0, respectively),
as depicted on FIG. 21A). FIGS. 21A-C depict examples of one or
more (e.g., additional) available reconstructed samples at the
right face boundary (e.g., FIG. 21A), bottom face boundary (e.g.,
FIG. 21B), and bottom right face boundary (e.g., FIG. 21C).
Reconstructed sample(s) depicted using a hatched pattern in FIGS.
21A-C may be located outside of the current block (e.g., or current
face). A coding device may apply pre-processing to one or more of
the reconstructed samples. For example, pre-processing may include,
but not limited to filtering, interpolation, and/or resampling. If
the coding device applies pre-processing (e.g., filtering,
interpolation, and/or resampling) on the one or more of the
reconstructed samples located on the left side of the current
block, the coding device may apply similar (e.g., same)
pre-processing on the one or more reconstructed samples located on
the right side of the current block.
[0109] In examples, if the coding device determines that the
current block is at located at the bottom face boundary of a face
associated with a frame-packed picture, the coding block may use
one or more reconstructed samples located below the current block
(e.g., R.sub.0,N+1 . . . R.sub.2N,N+1) (e.g., in addition to the
one or more reconstructed samples associated with a block(s)
located on the left and/or above the current block (e.g., R.sub.0,0
. . . R.sub.0,N and/or R.sub.0,0 . . . R.sub.2N,0, respectively),
as depicted on FIG. 21B). If the coding device applies
pre-processing (e.g., filtering, interpolation, and/or resampling)
on the reconstructed sample(s) located above the current block, the
coding device may apply similar (e.g., same) pre-processing on the
reconstructed sample(s) located below the current block.
[0110] In examples, if the coding device determines that the
current block is located at the bottom right face boundary of a
face associated with a frame-packed picture, the coding block may
use one or more reconstructed samples located on the right side of
and below the current block (e.g., R.sub.N+1,0 . . . R.sub.N+1,N+1
and/or R.sub.0,N+1 . . . R.sub.N+1,N+1, respectively) (e.g., in
addition to the one or more reconstructed samples associated with a
block(s) located on the left and/or above the current block (e.g.,
R.sub.0,0 . . . R.sub.0,N and/or R.sub.0,0 . . . R.sub.N,0,
respectively), as depicted on FIG. 21C). If the coding device
applies pre-processing (e.g., filtering, interpolation, and/or
resampling) on the reconstructed sample(s) located on the left side
of and/or above the current block, the coding device may apply
similar (e.g., same) pre-processing on the reconstructed sample(s)
located on the right side of and/or below the current block.
[0111] The coding device may use one or more reference sample lines
in one or more (e.g., all) cases described herein. The coding
device may apply one or more cases described herein to a
rectangular block(s).
[0112] If a current block associated with a face is at a right face
boundary of the face, a sample(s) located on a cross-face boundary
neighboring block (e.g., that is located to the right side of the
current block) (e.g., R.sub.N+1,0 . . . R.sub.N+1,2N) may be used
as depicted on FIGS. 21A-C. The reference sample(s) to be predicted
that is derived from the cross-face boundary neighboring block
(e.g., R.sub.N+1,0 . . . R.sub.N+1,2N) may be located closer to the
samples located on the above right (AR) side of the current block
(e.g., R.sub.N+1,0 . . . R.sub.2N,0). The reference sample(s)
(e.g., R.sub.N+1,0 . . . R.sub.N+1,2N) may be filtered. For
example, the one or more reference samples (e.g., R.sub.N+1,0 . . .
R.sub.N+1,2N) may be filtered prior to performing prediction (e.g.,
similar to the intra prediction process in HEVC).
[0113] A cross-face boundary neighboring block may be used to
predict the current block (e.g., as described herein). A reference
row or a reference column (e.g., depending on the directionality of
the selected prediction mode) may be used. The above reference row
may be extended to the right, e.g., by projecting the right
reference column, as depicted in FIG. 22A. FIGS. 22A-B depict
examples of intra prediction at right face boundary (e.g., FIG.
22A) and bottom face boundary (e.g., FIG. 22B). The bold arrow
shown in FIGS. 22A-B may represent the prediction direction and the
thin arrows may represent the reference sample projection.
Reference samples depicted using dashed lines in FIGS. 22A-B may be
located outside of the current face. Considering the intra angular
prediction directions defined in FIG. 10, samples R.sub.N+1,N . . .
R.sub.N+1,2N may not be used for extending the above reference row
to the right. Samples R.sub.N+1,N . . . R.sub.N+1,2N may be used
for filtering the right reference column.
[0114] The samples located below right of the current block (e.g.,
R.sub.N+1,N+1 . . . R.sub.N+1,2N) may be used when considering
intra angular prediction directions, e.g., covering a wider range
than the
[ - 3 .pi. 4 , .pi. 4 ] ##EQU00004##
range depicted in FIG. 10. The right reference column may be used,
as depicted in FIG. 23A, or extended upwards by projecting the
above reference row, as depicted in FIG. 23B. FIGS. 23A-D depict
examples of additional intra prediction modes at the right face
boundaries (e.g., FIGS. 23A-B) and bottom face boundaries (e.g.,
FIGS. 23C-D). The bold arrow shown in FIGS. 23A-D may represent the
prediction direction and the thin arrows may represent the
reference sample projection. Reference samples depicted using
dashed lines in FIGS. 23A-D may be located outside of the current
face.
[0115] For horizontal angular directions, a blending between the
left and the right reference columns may be performed to predict
the current block samples, as depicted in FIGS. 24A-B. A linear
weighting or similar process may be performed, e.g., considering
the distance between the sample to be predicted and the reference
samples. In examples, the projected pixel locations may have
negative indexes. If the projected pixel locations have negative
indexes, the left reference column may be extended upwards, e.g.,
by projecting the above reference row, as depicted in FIG. 24A,
and/or the right reference column may be extended upwards, e.g., by
projecting the above reference row, as depicted in FIG. 24B. FIGS.
24A-D depict example bi-directional intra prediction at the right
face boundaries (e.g., FIGS. 24A-B) and bottom face boundaries
(e.g., FIGS. 24C-D). The bold arrow shown in FIGS. 24A-D may
represent the prediction direction and the thin arrows may
represent the reference sample projection. Reference samples
depicted using dashed lines in FIGS. 24A-D may be located outside
of the current face.
[0116] For DC mode, if the current block is at the right face
boundary, the samples located on the right side of the current
block may be used to compute the DC predictor:
p = 1 3 N ( i = 1 N R i , 0 + j = 1 N R 0 , j + j = 1 N R N + 1 , j
) ( 19 ) ##EQU00005##
[0117] For planar mode, if the current block is at the right face
boundary, the samples R.sub.N+1,1 . . . R.sub.N+1,N obtained, e.g.,
using geometry padding, may be used for the horizontal predictor.
For the vertical predictor, the value of sample R.sub.i,N+1, i=1 .
. . N, may be interpolated from R.sub.0,N+1 and R.sub.N+1,N+1,
e.g., using a linear weighting or similar process considering the
distance to these two samples. The value of R.sub.N+1,N+1 may be
obtained from the corresponding available reconstructed sample.
[0118] If the current block is at the bottom face boundary, the
samples located below the current block (e.g., R.sub.0,N+1 . . .
R.sub.2N,N+1) may be used as depicted on FIG. 21B. In this manner,
the reference samples (e.g., derived from the reconstructed
samples) derived from a block associated with the cross-face
boundary neighboring block as described herein may be closer to the
current block samples to be predicted. The reference samples
R.sub.0,N+1 . . . R.sub.2N,N+1 may be filtered, e.g., prior to
performing prediction. For example, the reference samples
R.sub.0,N+1 . . . R.sub.2N,N+1 may be filtered prior to performing
prediction similar to the intra prediction process (e.g., in
HEVC).
[0119] For example, the left reference column may be extended
downwards (e.g., by projecting the below reference row, as depicted
in FIG. 22B). Considering the intra angular prediction directions
in FIG. 10, samples R.sub.N,N+1 . . . R.sub.2N,N+1 may not be used
for extending the left reference column downwards. The samples
R.sub.N,N+1 . . . R.sub.2N,N+1 may be used for filtering the below
reference row.
[0120] The samples located below right of the current block (e.g.,
R.sub.N+1,N+1 . . . R.sub.2N,N+1) may be used when considering
intra angular prediction directions, e.g., covering a wider range
than the
[ - 3 .pi. 4 , .pi. 4 ] ##EQU00006##
range depicted in FIG. 10. In this case, the below reference row
may be used, as depicted in FIG. 23C. The below reference row may
be extended to the left, e.g., by projecting the left reference
column, as depicted in FIG. 23D.
[0121] For vertical angular directions, a blending between the
above and below reference rows may be performed to predict the
current block samples, as depicted in FIGS. 24C-D. In this case, a
linear weighting or similar process may be performed, e.g.,
considering the distance between the sample to be predicted and the
reference samples. In some cases, the projected pixel locations may
have negative indexes. If the projected pixel locations have
negative indexes, the above reference row may be extended to the
left, e.g., by projecting the left reference column, as depicted in
FIG. 24C. The below reference row may be extended to the left,
e.g., by projecting the left reference column, as depicted in FIG.
24D.
[0122] For DC mode, if the current block is at the bottom face
boundary, the samples located below the current block may be used
to compute the DC predictor:
p = 1 3 N ( i = 1 N R i , 0 + j = 1 N R 0 , j + i = 1 N R i , N + 1
) ( 20 ) ##EQU00007##
[0123] For planar mode, if the current block is at the bottom face
boundary, samples R.sub.1,N+1 . . . R.sub.N,N+1 obtained using
geometry padding may be used for the vertical predictor. For the
horizontal predictor, the value of sample R.sub.N+1,j j=1 . . . N,
may be interpolated from R.sub.N+1,0 and R.sub.N+1,N+1, e.g., using
a linear weighting or similar process considering the distance to
these two samples. The value of R.sub.N+1,N+1 may be obtained from
the corresponding available reconstructed sample.
[0124] If the current block is at the bottom right face boundary,
the samples located on the right side of the current block (e.g.,
R.sub.N+1,0 . . . R.sub.N+1,N+1) may be used. The samples located
below the current block (e.g., R.sub.0,N+1 . . . R.sub.N+1,N+1) may
be used as depicted on FIG. 21C. The reference samples derived from
the cross-face boundary neighboring block as described herein may
be closer to the current block samples to be predicted.
[0125] For DC mode, if the current block is at the bottom right
face boundary, the samples located on the right side of and/or
below the current block may be used to compute the DC
predictor:
p = 1 4 N ( i = 1 N R i , 0 + j = 1 N R 0 , j + i = 1 N R i , N + 1
+ j = 1 N R N + 1 , j ) ( 21 ) ##EQU00008##
[0126] For planar mode, if the current block is at the bottom right
face boundary, the samples R.sub.N+1,1 . . . R.sub.N+1,N obtained
using geometry padding may be used for the horizontal predictor,
and samples R.sub.1,N+1 . . . R.sub.N,N+1 obtained using geometry
padding may be used for the vertical predictor.
[0127] One or more reference sample lines may be used in one or
more (e.g., all) cases described herein, and rectangular blocks may
be configured to use reconstructed samples as described herein.
[0128] If a current block is at the right, bottom, and/or bottom
right face boundary, e.g., of a face in a frame-packed picture
associated with 360-degree video, additional boundary prediction
filtering(s) (e.g., after intra prediction) may be applied. For
example, additional boundary prediction filtering(s) after intra
prediction may be applied to reduce discontinuities at face
boundaries. The filtering described herein may be applied on top of
boundary prediction filtering. In examples, the filtering described
herein may be applied to the block's top row(s) (e.g., top-most
row(s)) and/or left column(s) (e.g., left-most column(s)).
[0129] For horizontal intra mode(s), e.g., that may be close to
horizontal, if the current block is at the right face boundary, the
predicted sample(s) s.sub.i,j of the block located at the right
column (e.g., right-most column) may be adjusted, e.g., using the
right reference column R.sub.i,j as follows:
s.sub.N,j=s.sub.N,j+(R.sub.N+1,j-R.sub.N+1,0) j=1 . . . N (22)
[0130] FIGS. 25 A-H depict example boundary prediction filtering at
right face boundary for intra mode 2 (e.g., FIG. 25A), intra modes
3-6 (e.g., FIG. 25B), intra modes 7-9 (e.g., FIG. 25C), intra mode
10 (e.g., FIG. 25D), intra modes 11-17 (e.g., FIG. 25E), intra mode
18 (e.g., FIG. 25F), intra modes 19-21 (e.g., FIG. 25G), and intra
mode 22 (e.g., FIG. 25H). Reference samples depicted using dashed
lines in FIGS. 25A-H may be located outside of the current
face.
[0131] For other intra angular mode(s), if the current block is at
the right face boundary, the predicted sample(s) s.sub.i,j of the
block located at the right column(s) (e.g., right-most column(s))
may be filtered, e.g., using the right reference column R.sub.i, j
as follows:
For mode 2 (e.g., FIG. 25A)
s.sub.N-.delta.,j=a(.delta.)s.sub.N-.delta.,j+b(.delta.)R.sub.N+1,j-1-.d-
elta. (23)
j=1 . . . N,.delta.=0 . . . min(j-1, D),
a(.delta.)+b(.delta.)=1
For modes 3-6 (e.g., FIG. 25B) and/or modes 7-9 (e.g., FIG.
25C)
s.sub.N,j=as.sub.N,j+bR.sub.N+1,j+cR.sub.N+1,j-1 (24)
j=1 . . . N, a+b+c=1
For mode 10 (e.g., FIG. 25 D)
s.sub.N-.delta.,j=a(.delta.)s.sub.N-.delta.,j+b(.delta.)R.sub.N+1,j
(25)
j=1 . . . N, .delta.=0 . . . D, a(.delta.)+b(.delta.)=1
For modes 11-17 (e.g., FIG. 25 E)
s.sub.N,j=as.sub.N,j+bR.sub.N+1,j+cR.sub.N+1,j-1 (26)
j=1 . . . N, a+b+c=1
For mode 18 (e.g., FIG. 25F)
s.sub.N-.delta.,j=a(.delta.)s.sub.N-.delta.,j+b(.delta.)R.sub.N+1,j+1+.d-
elta. (27)
j=1N . . . N, =0 . . . D, a(.delta.)+b(.delta.)=1
For modes 19-21 (e.g., FIG. 25G)
s.sub.N,j=as.sub.N,j+bR.sub.N+1,j+1+cR.sub.N+1,j+2 (28)
j=1 . . . N, a+b+c=1
For modes 22 (e.g., FIG. 25H)
s.sub.N,j=as.sub.N,j+bR.sub.N+1,j+2+cR.sub.N+1,j+3 (29)
j=1 . . . N, a+b+c=1
where D may be a parameter that controls the number of right-most
columns and may be filtered. The weights `a`, `b`, and `c` may be
chosen, e.g., depending on the intra mode and/or distance to the
reference samples. For example, a look up table (LUT) may be used
to get the parameter(s) as a function of the intra mode. In the
LUT, depending on the intra mode, higher weight may be given to a
reference sample(s) that may be closer to the current position. For
example, for modes 2 and 18, the weights defined in Table 1 may be
used (e.g., Equations (23) and (27), respectively) to filter the
block right-most columns.
TABLE-US-00001 TABLE 1 Weights for diagonal, vertical, and/or
horizontal mode .delta. a (.delta.) b (.delta.) 0 8/16 8/16 1 12/16
4/16 2 14/16 2/16 3 15/16 1/16
The weights defined in Table 1 may be used for the horizontal mode
(e.g., mode 10). For modes 19 to 22, the weights defined in Table 2
may be used.
TABLE-US-00002 TABLE 2 Weights for near diagonal mode Mode a b c 19
8/16 6/16 2/16 20 12/16 2/16 2/16 21 12/16 1/16 3/16 22 12/16 3/16
1/16
[0132] For the other mode(s), the weights may be determined such
that the values for `b` and/or `c` may map to the position in the
right reference sample column. The predicted sample may be
projected considering the opposite angular direction and may weigh
(e.g., equally weigh) this value with the predicted sample value.
For example, for modes 3 to 9, the weights may be determined as
a = 0.5 , b = .DELTA. y 2 .DELTA. x , c = 0.5 - b ,
##EQU00009##
where .DELTA..sub.x and .DELTA..sub.y may be the horizontal and
vertical components of the angular direction, respectively.
[0133] For vertical intra mode(s), e.g., which may be close to
vertical, if the current block is at the bottom face boundary,
e.g., of a face in a frame-packed picture associated with
360-degree video, the predicted samples s.sub.i,j of the block
located at the bottom-most row may be adjusted, e.g., using the
below reference row R.sub.i,j as follows:
s.sub.i,N=s.sub.i,N+(R.sub.i,N+1-R.sub.0,N+1) i=1 . . . A (30)
[0134] Filtering (e.g., boundary prediction filtering) may be
applied to the current block, e.g., using the cross-face boundary
neighboring block as described herein. FIGS. 26 A-H depict example
boundary prediction filtering at bottom face boundary for intra
mode 14 (e.g., FIG. 26A), intra modes 15-17 (e.g., FIG. 26B), intra
mode 18 (e.g., FIG. 26C), intra modes 19-25 (e.g., FIG. 26D), intra
mode 26 (e.g., FIG. 26E), intra modes 27-29 (e.g., FIG. 26F), intra
modes 30-33 (e.g., FIG. 26G), and intra mode 34 (e.g., FIG. 26H).
Reference sample(s) depicted using dashed lines in FIGS. 26A-H may
be located outside of the current face.
[0135] For other intra angular mode(s), if the current block is at
the bottom face boundary, the predicted sample(s) s.sub.i,j of the
block located at the bottom row(s) (e.g., bottom-most row(s)) may
be filtered, e.g., using the below reference row R.sub.i,j as
follows:
For modes 14 (e.g., FIG. 26A)
s.sub.i,N=as.sub.i,N+bR.sub.i+2,N+1+cR.sub.i+3,N+1 (31)
j=1 . . . N, a+b+c=1
For modes 15-17 (e.g., FIG. 26B)
s.sub.i,N=as.sub.i,N+bR.sub.i+1,N+1+cR.sub.i+2,N+1 (32)
j=1 . . . N, a+b+c=1
For mode 18 (e.g., FIG. 26C)
s.sub.i,N-.delta.=a(.delta.)s.sub.i,N-.delta.+b(.delta.)R.sub.i+1+.delta-
.,N+1 (34)
i=1 . . . N, .delta.=0 . . . D, a(.delta.)+b(.delta.)=1
For modes 19-25 (e.g., FIG. 26D)
s.sub.i,N=as.sub.i,N+bR.sub.i,N+1+cR.sub.i+1,N+1 (34)
i=1 . . . N, a+b+c=1
For mode 26 (e.g., FIG. 26E)
s.sub.i,N-.delta.=a(.delta.)s.sub.i,N-.delta.+b(.delta.)R.sub.i,N+1
(35)
i=1 . . . N, .delta.=0 . . . D, a(.delta.)+b(.delta.)=1
For modes 27-29 (e.g., FIG. 26F) and modes 30-33 (e.g., FIG.
26G)
s.sub.i,N=as.sub.i,N+bR.sub.i-1,N+1+cR.sub.i,N+1 (36)
i=1 . . . N, a+b+c=1
For mode 34 (e.g., FIG. 26H)
s.sub.i,N-.delta.=a(.delta.)s.sub.i,N-.delta.+b(.delta.)R.sub.i-1-.delta-
.,N+1 (37)
i=1 . . . N, .delta.=0 . . . min(i-1, D),
a(.delta.)+b(.delta.)=1
where D may be a parameter that controls the number of bottom-most
rows and may be filtered. The weights `a`, `b`, and `c` may be
selected, e.g., depending on the intra mode and/or distance to the
reference samples.
[0136] For intra angular mode(s), if the current block is at the
bottom right face boundary, e.g., of a face in a frame-packed
picture associated with 360-degree video, the predicted samples of
the block located at the right column(s) (e.g., right-most
column(s)) may be filtered, e.g., using the right reference column,
and the block located at the bottom row(s) (e.g., bottom-most
row(s)) may be filtered, e.g., using the below reference row, as
described herein.
[0137] For DC mode, if the current block is at the right face
boundary, e.g., of a face in a frame-packed picture associated with
360-degree video, the predicted sample(s) of the block located at
the right column(s) (e.g., right-most column(s)) may be filtered,
e.g., using the right reference column (e.g., according to Equation
(25)). If the current block is at the bottom face boundary, e.g.,
of a face in a frame-packed picture associated with 360-degree
video, the predicted sample(s) of the block located at the bottom
row(s) (e.g., bottom-most row(s)) may be filtered, e.g., using the
below reference row (e.g., according to Equation (35)). If the
current block is at the bottom right face boundary, e.g., of a face
in a frame-packed picture associated with 360-degree video, the
predicted sample(s) of the block located at the right column(s)
(e.g., right-most column(s)) may be filtered, e.g., using the right
reference column, and the block located at the bottom row(s) (e.g.,
bottom-most row(s)) may be filtered, e.g., using the below
reference row (e.g., according to Equations (25) and (35)).
[0138] The filtering process may be implemented, e.g., using fixed
point precision and/or bit shift operation. Similar filtering
operations may be applied to the block located at the right
column(s) (e.g., right-most column(s)) and/or the block located at
the bottom row(s) (e.g., bottom-most row(s)), e.g., when
considering finer intra angular granularity and/or rectangular
blocks.
[0139] For in-loop filtering, filtering may be applied across one
or more (e.g., all) face boundaries. For example, the filtering may
be applied across face boundaries including the right and/or bottom
face boundaries. If a current block is on the left (e.g., or above)
face boundary, e.g., of a face in a frame-packed picture associated
with 360-degree video, the left (e.g., or above) reconstructed
sample(s) may be used for filtering the block located at the
left-most column(s) (e.g., or top-most row(s)), even if the block
may be on the frame-packed picture boundary. If a block is on the
top left face boundary, e.g., of a face in a frame-packed picture
associated with 360-degree video, the left and above reconstructed
sample(s) may be used for filtering the block located at the
left-most column(s) and top-most row(s), respectively, even if the
block may be on the frame-packed picture boundary. If a block is on
the right (e.g., or bottom) face boundary, e.g., of a face in a
frame-packed picture associated with 360-degree video, the right
(e.g., or below) reconstructed sample(s) may be used for filtering
the block located at the right-most column(s) (e.g., or bottom-most
row(s)), even if the block may be on the frame-packed picture
boundary. If a block is on the bottom right face boundary, e.g., of
a face in a frame-packed picture associated with 360-degree video,
the right and below reconstructed sample(s) may be used for
filtering the block located at the right-most column(s) and
bottom-most row(s), respectively, even if the block may be on the
frame-packed picture boundary. The reconstructed sample(s) may be
outside of the current face, and the reconstructed samples may be
obtained, e.g., using geometry padding.
[0140] For cross-component linear model prediction, reconstructed
sample(s) (e.g., additional resource sample(s)) may be used. For
example, the reconstructed sample(s) (e.g., additional resource
sample(s)) may be based on the position of the current block inside
a geometry face.
[0141] FIGS. 27A-C depict example locations of the samples used for
cross-component linear model prediction at the right face boundary
(e.g., FIG. 27A), bottom face boundary (e.g., FIG. 27B), and bottom
right face boundary (e.g., FIG. 27C). Reconstructed samples
depicted using dotted lines in FIGS. 27A-C may be located outside
of the current face. If the current block is at the right face
boundary, e.g., of a face in a frame-packed picture associated with
360-degree video, the reconstructed sample(s) located on the right
side of the current block may be used, e.g., in addition to the
reconstructed sample(s) located on the left side of and/or the
reconstructed sample(s) located above the current block to predict
the parameter(s) of the linear model, as depicted on FIG. 27A. In
this case, the linear model parameter(s) may be computed as follows
(e.g., Equations (38)-(40)):
[0142] Equation (38) is shown in FIG. 28 and
.beta. = ( i = 1 N C i , 0 + j = 1 N C 0 , j + j = 1 N C N + 1 , j
) - .alpha. ( i = 1 N L i , 0 ' + j = 1 N L 0 , j ' + j = 1 N L N +
1 , j '' ) 3 N ( 39 ) ##EQU00010##
where L.sub.i,j'' may be the downsampled reconstructed luma
samples, e.g., located on the right side of the current block.
L.sub.i,j'' may be computed, e.g., considering the availability of
reconstructed luma samples and/or the chroma location, as
follows:
L i , j '' = L 2 i - 1 , 2 j - 1 + L 2 i - 1 , 2 j 2 ( 40 )
##EQU00011##
[0143] One or more downsampling filters may be applied, e.g., using
a cross-face boundary neighboring block(s). If a pre-processing
(e.g., filtering) is applied on the reconstructed samples located
on the left side of the current block, a similar (e.g., same)
pre-processing may be applied on the reconstructed samples located
on the right side of the current block.
[0144] If the current block is at the bottom face boundary, e.g.,
of a face in a frame-packed picture associated with 360-degree
video, the reconstructed samples located below the current block
may be used, e.g., in addition to the reconstructed samples located
on the left side of and/or the reconstructed samples located above
the current block, to predict the parameters of the linear model,
as depicted on FIG. 27B. In this case, the linear model parameters
may be computed as follows (e.g., Equations (41)-(42)): Equation
(41) is shown in FIG. 28 and
.beta. = ( i = 1 N C i , 0 + j = 1 N C 0 , j + i = 1 N C i , N + 1
) - .alpha. ( i = 1 N L i , 0 ' + j = 1 N L 0 , j ' + i = 1 N L i ,
N + 1 ' ) 3 N ( 42 ) ##EQU00012##
[0145] The reconstructed luma samples located below the current
block may be downsampled (e.g., according to Equation (16)). One or
more downsampling filters may be applied, e.g., using a cross-face
boundary neighboring block(s). If a pre-processing (e.g.,
filtering) is applied on the reconstructed samples located above
the current block, a similar (e.g., same) pre-processing may be
applied on the reconstructed samples located below the current
block.
[0146] If the current block is at the bottom right face boundary,
e.g., of a face in a frame-packed picture associated with
360-degree video, the reconstructed samples located on the right
side of and below the current block may be used (e.g., in addition
to the reconstructed samples located on the left side of and the
reconstructed samples located above the current block) to predict
the parameters of the linear model, as depicted on FIG. 27C. The
linear model parameters may be computed as follows (e.g., Equations
(43) and (44)):
[0147] Equations (43) and (44) are shown in FIG. 28.
[0148] For a rectangular block(s), the neighboring samples of the
longer boundary may be subsampled, e.g., using a cross-face
boundary neighboring block(s). For example, the neighboring samples
of the longer boundary of the rectangular block may be subsampled
to have the same number of samples to the shorter boundary. The
cross-component linear model prediction described herein may be
used to predict between two chroma components (e.g., in the sample
domain or in the residual domain). Multiple cross-component linear
models may be used at the face boundary, where one or more
cross-component linear model predictions may be defined on a range
of sample values and may be applied as described herein. If a
reconstructed sample(s) is outside of the current face, the
reconstructed samples may be obtained, e.g., using geometry
padding.
[0149] One or more available blocks and/or samples located on the
other side of the right and/or bottom face boundaries (e.g.,
opposite side of a face boundary from the current block location
and in the same direction of the coding order relative to the
current block or cross-face boundary neighboring block) may be used
for prediction. The availability of face neighbor blocks and/or
samples may depend on the coding order in which the blocks of the
frame packed picture are processed. For example, FIG. 29A depicts
an example raster scan order (e.g., from top to bottom and/or from
left to right) for CMP 3.times.2 packing configuration. The blocks
may be processed face-by-face, e.g., using a raster scan order
within one or more faces (e.g., as illustrated in FIG. 29B). Using
the face scan order shown in FIG. 29B may increase the availability
of the face neighbor blocks and/or samples. One or more different
frame packing configurations may be used to achieve a similar
result. For example, in the situation depicted in FIG. 29A, if a
6.times.1 packing configuration is used (e.g., instead of or in
addition to the 3.times.2 packing configuration), the raster scan
order may process one or more faces one by one. The block coding
order (e.g., processing order) may be different depending on the
used face arrangement.
[0150] A constraint(s) may be applied, e.g., during block
partitioning. For example, a constraint(s) may be applied during
block partitioning to reduce block overlapping over two or more
faces. If one or more coding tree units (CTUs) are used, the CTUs
may be configured such that one or more (e.g., all) coded blocks
within a CTU belongs to the same face. If the face size is not a
multiple of the CTU size, the overlapping CTUs may be used where
the blocks that are within the face that the CTU belongs to may be
coded. FIG. 30 depicts an example CTU and block partitioning of a
face where the face size is not a multiple of the CTU size. The
solid lines shown in FIG. 30 may represent the face boundaries. The
dashed lines may represent the CTU boundaries and the dotted lines
may represent the block boundaries. Blocks depicted using a hatched
pattern may be located outside of the current face. One or more
different block scan orders may be used for the intra and inter
coded frames. For example, intra-coded frames may use the face scan
order (e.g., FIG. 29B). Inter-coded frames may use the raster scan
order (e.g., FIG. 29A). Different scan order(s) between and/or
within different faces may be used, e.g., based on the coding mode
(e.g., prediction mode) of the face.
[0151] Loop filter operation(e.g., as described herein where using
neighboring samples from already-coded faces to the right and/or
bottom boundaries in loop filtering operations) may be enabled or
disabled. For example, loop filter operation may be enabled or
disabled based on face scan order and/or frame packing
configuration. If proper neighboring samples in the 3D geometry are
not used in deblocking filter or other in-loop filters,
objectionable visual artefacts in the form of face seams may become
visible in the reconstructed video. For example, when the
reconstructed video is used to render a viewport and displayed to
the user, e.g., via head mount device (HMD) or via 2D screen, face
seams may become visible in the reconstructed video. For example,
FIG. 18B illustrates a 3.times.2 CMP example. The 3 faces in the
top half shown in FIG. 18B may be horizontally continuous in the 3D
geometry. The 3 faces in the bottom half may be horizontally
continuous in the 3D geometry. The top half and bottom half may be
discontinuous in the 3D geometry. The 3.times.2 CMP picture may be
coded using two tiles (e.g., a tile for the top half and a tile for
the bottom half of the 3.times.2 CMP picture) and loop filtering
may be disabled across the tile boundaries. For example, loop
filtering may be disabled across the tile boundaries, e.g., by
setting the value of the picture parameter set (PPS) syntax element
loop_filter_across_tiles_enabled_flag to 0. Loop filtering may be
disabled, e.g., to avoid applying deblocking and/or other in-loop
filters across the discontinuous edge (e.g., the horizontal edge
separating the top and bottom halves).
[0152] Face scan order may be used to encode and/or decode the
blocks in a frame-packed picture. The 6 faces shown in FIG. 18B may
be processed using the order shown in FIG. 29B. Face scan order may
be achieved by aligning the 6 faces with 6 tiles. In this case,
setting an indicator (e.g., loop_filter_across_tiles_enabled_flag
to 0) may cause deblocking and in-loop filters to be disabled
across the horizontal edges between tiles (e.g., which may be
discontinuous and may be disabled) and across the vertical edges
(e.g., which may be continuous and may not be disabled). Whether
the edges loop filters are applied or the edges loop filters are
not applied may be specified. The type of loop filters may be
considered. For example, loop-filters, such as deblocking and/or
Adaptive Loop Filters (ALF), may be N-tap filters that use
neighboring samples in the filtering process. One or more of the
neighboring samples used for the filters may be cross discontinuous
edges. Loop-filters, such as Sample Adaptive Offset (SAO), may add
an offset to correct the decoded sample value at the current
position. In examples, loop-filters (e.g., SAO) may not use
neighboring sample values in the filtering operation. Deblocking
and/or ALF across some tiles and/or face boundaries may be
disabled. SAO may be enabled. For example, deblocking and/or ALF
across some tiles and/or face boundaries may be disabled, while SAO
may be enabled.
[0153] Extensions to an indicator (e.g.,
loop-filter_across_tiles_enabled_flag) may be indicated (e.g., in a
bitstream) to a coding device. The indicator (e.g.,
loop_filter_across_tiles_enabled_flag) syntax element may be
separated. For example, the loop_filter_across_tiles_enabled_flag
syntax element may be separated into two or more syntax elements
(e.g., two syntax elements). In examples, whether to apply loop
filter to the horizontal edges may be indicated, e.g., via a syntax
element. In examples, whether to apply loop filter to the vertical
edges may be indicated, e.g., via a syntax element.
[0154] The indicator (e.g., loop_filter_across_tiles_enabled_flag)
syntax element may be separated into two or more syntax elements
may be indicated (e.g., in a bitstream) to a coding device. Whether
to enable or disable loop filters across a given edge may be
indicated, e.g., via the two or more separated syntax elements. For
example, the frame-packed projection format including M.times.N
faces (e.g., FIG. 18B where M=3 and N=2) may be considered. In the
frame-packed projection format including M.times.N faces,
(M-1).times.N vertical edges between faces in the picture may
exist, and M.times.(N-1) horizontal edges between faces in the
picture may exist. In this case, (M-1).times.N+M.times.(N-1)
indications (e.g., flags) may specify whether to enable or disable
one or more of the horizontal and/or vertical edges. The semantics
of the indicator (e.g., loop_filter_across_tiles_enabled_flag)
syntax element may be adapted to disable or enable loop filters
across edges between continuous faces. In this case, loop filters
may be disabled across edges between discontinuous faces, e.g., to
avoid the occurrence of seam. Signaling may be configured to
specify which edges are between continuous faces and/or which edges
are between discontinuous faces.
[0155] The indicator (e.g., loop_filter_across_tiles_enabled_flag)
syntax element may be separated into two or more syntax elements.
The two or more syntax elements may be used to control a different
type of loop filter. For example, an indication (e.g., flag) may be
used to enable or disable deblocking. An indication (e.g., flag),
for example, may be used to enable or disable ALF. An indication
(e.g., flag), for example, may be used to enable or disable SAO. If
more loop filters are used in the video encoder and/or decoder
(e.g., shown in FIG. 7 and FIG. 8), more indication (e.g., flags)
may be used. The indicator (e.g.,
loop_filter_across_tiles_enabled_flag) syntax element may be
separated (e.g., into two syntax elements). For example, an
indication (e.g., flag) may be controlling loop filters that use
neighboring samples. A different indication (e.g., flag), for
example, may be controlling loop filters that do not use
neighboring samples. The indicator (e.g.,
loop_filter_across_tiles_enabled_flag) syntax element may indicate
whether to disable or enable loop filters that use neighboring
samples. In this case, loop filters that do not use neighboring
samples may be enabled.
[0156] The extensions described herein may be combined. For
example, if multiple indications (e.g., flags) are used, one or
more indications (e.g., flags) may be used for controlling a type
of loop filter, and the semantics of the one or more indications
(e.g., flags) may be adapted accordingly. For example, the
semantics of the one or more indications may be adapted to control
whether to apply that filter to edges across continuous faces, and
that filter may be disabled for edges across discontinuous faces
(e.g., to avoid the occurrence of seam).
[0157] The extensions to the indicator (e.g.,
loop_filter_across_tiles_enabled_flag) described herein may be
using tiles as an exemplary manner. Those skilled in the art would
appreciate that they may apply to other face levels (e.g., slices).
For example, pps_oop_filter_across_slices_enabled_flag and/or
slice_loop_filter_across_slices_enabled_flag, which control whether
to apply loop filters across slides may be used as an indicator
(e.g., different indicator). As the coded blocks within a CTU
belong to the same tile and/or slice, the tile and/or slice size
may be a multiple of the CTU size. The face size may not be a
multiple of the CTU size. Tiles and/or slices described herein may
be replaced with faces (e.g., to avoid using tiles and/or slices
and to change the semantic described herein). For example, an
indicator (e.g., loop_filter_across_tiles_enabled_flag) syntax
described herein and its one or more extensions may be replaced
with (e.g., or used in conjunction with) a different indicator
(e.g., loop_filter_across_faces_enabled_flag). Face-based loop
filter control indications (e.g., flags) may work when tiles and/or
slices are enabled. In this case, such face-based loop filter
control indications (e.g., flags) may be applicable to edges on
face boundaries, and the tile and/or slice-based loop filter
control indications (e.g., flags) may be applied to edges on tile
and/or slice boundaries.
[0158] Overlapping CTUs such that one or more (e.g., all) coded
blocks within a CTU belonging to the same face and the blocks that
are within the face that the CTU belongs to may be coded. In this
way, tiles and/or slices may be used (e.g., even if the face size
is not a multiple of the CTU size).
[0159] For CMP and/or related cube-based geometries, 3.times.2
packing configuration may be used. For example, the 3.times.2
packing configuration may be used for a representation (e.g.,
compact representation) and may form a rectangular frame packed
picture. The 3.times.2 packing configuration may skip filling the
empty regions with default (e.g., void) samples to form a
rectangular frame packed picture (e.g., 4.times.3 packing
configuration) shown in FIG. 2B. One or more faces of the 3.times.2
packing configuration may be arranged such that the discontinuity
between two neighboring faces in the frame picture may be reduced.
A 3.times.2 packing configuration may be defined such that the
right, front, and left faces may be placed in the top row (e.g., in
this particular order), and the bottom, back, and top faces may be
placed in the bottom row (e.g., in this particular order), as
depicted in FIG. 31. FIG. 31 illustrates an example 3.times.2
packing configuration (e.g., having the right, front, and left
faces placed in the top row and the bottom, back, and top faces
placed in the bottom row). The dashed lines from FIG. 31 may
represent the CTU boundaries. The arrow may represent the shared
boundary between two faces. Within a face row (e.g., each face
row), the faces may rotated. For example, the face row may rotate
to minimize the discontinuities between two neighboring faces. The
face size may not be a multiple of the CTU size. Part of the second
face row may be coded, e.g., before the first face row is fully
coded. When coding one or more blocks in the bottom, back, and top
faces, neighboring blocks in the right, front, and/or left faces
may not be available. For example, for the 3.times.2 packing
configuration depicted in FIG. 31, when encoding the blocks in the
first (e.g., partial) CTU row of the bottom face (e.g., shaded area
in FIG. 31), information may not be inferred from the neighboring
blocks in the front and left faces, as the corresponding
neighboring blocks may not have been encoded yet. Similarly, for
the back face, the first blocks within a width of size h=mod(face
size, CTU size), where mod(x,y) may be the modulo operator, in the
first (e.g., partial) CTU row (e.g., shaded area in FIG. 31) may
not infer information from the neighboring blocks in the left face,
as the corresponding neighboring blocks may not have been encoded
yet.
[0160] A 3.times.2 packing configuration may be used and/or
signaled in a bitstream, e.g., to/from a coding device. For
example, when 3.times.2 packing configuration described herein is
used, information from one or more neighboring faces in the first
face row may be inferred for the faces located in the second face
row. The 3.times.2 packing configuration may be defined such that
the right, front, and left faces are placed in the first face row
(e.g., in this particular order), and the top, back, and bottom
faces are placed in the second face row (e.g., in this particular
order), as depicted in FIG. 32. FIG. 32 illustrates an example
3.times.2 packing configuration (e.g., having the right, front, and
left faces in the first face row and the top, back, and bottom
faces in the second face row). Within a face row (e.g., each face
row), the faces may be rotated, e.g., to minimize the
discontinuities between two neighboring faces. For the 3.times.2
packing configuration shown in FIG. 32, one or more faces in the
second face row may be rotated by 180 degrees (e.g., in comparison
to the 3.times.2 packing configuration illustrated in FIG. 31).
With the configuration shown in FIG. 32, neighboring blocks in the
right, front, and left faces may be available when encoding the
top, back, and bottom faces.
[0161] The definition of front, back, left, right, top, and/or
bottom faces described herein may be relative. Rotation may be
applied to the cube to get a similar arrangement as described
herein.
[0162] FIG. 33A is a diagram illustrating an example communications
system 100 in which one or more disclosed embodiments may be
implemented. The communications system 100 may be a multiple access
system that provides content, such as voice, data, video,
messaging, broadcast, etc., to multiple wireless users. The
communications system 100 may enable multiple wireless users to
access such content through the sharing of system resources,
including wireless bandwidth. For example, the communications
systems 100 may employ one or more channel access methods, such as
code division multiple access (CDMA), time division multiple access
(TDMA), frequency division multiple access (FDMA), orthogonal FDMA
(OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word
DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM),
resource block-filtered OFDM, filter bank multicarrier (FBMC), and
the like.
[0163] As shown in FIG. 33A, the communications system 100 may
include wireless transmit/receive units (VRUs) 102a, 102b, 102c,
102d, a RAN 104/113, a CN 106/115, a public switched telephone
network (PSTN) 108, the Internet 110, and other networks 112,
though it will be appreciated that the disclosed embodiments
contemplate any number of WTRUs, base stations, networks, and/or
network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be
any type of device configured to operate and/or communicate in a
wireless environment. By way of example, the WTRUs 102a, 102b,
102c, 102d, any of which may be referred to as a "station" and/or a
"STA", may be configured to transmit and/or receive wireless
signals and may include a user equipment (UE), a mobile station, a
fixed or mobile subscriber unit, a subscription-based unit, a
pager, a cellular telephone, a personal digital assistant (PDA), a
smartphone, a laptop, a netbook, a personal computer, a wireless
sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT)
device, a watch or other wearable, a head-mounted display (HMD), a
vehicle, a drone, a medical device and applications (e.g., remote
surgery), an industrial device and applications (e.g., a robot
and/or other wireless devices operating in an industrial and/or an
automated processing chain contexts), a consumer electronics
device, a device operating on commercial and/or industrial wireless
networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d
may be interchangeably referred to as a UE.
[0164] The communications systems 100 may also include a base
station 114a and/or a base station 114b. Each of the base stations
114a, 114b may be any type of device configured to wirelessly
interface with at least one of the WTRUs 102a, 102b, 102c, 102d to
facilitate access to one or more communication networks, such as
the CN 106/115, the Internet 110, and/or the other networks 112. By
way of example, the base stations 114a, 114b may be a base
transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a
Home eNode B, a gNB, a NR NodeB, a site controller, an access point
(AP), a wireless router, and the like. While the base stations
114a, 114b are each depicted as a single element, it will be
appreciated that the base stations 114a, 114b may include any
number of interconnected base stations and/or network elements.
[0165] The base station 114a may be part of the RAN 104/113, which
may also include other base stations and/or network elements (not
shown), such as a base station controller (BSC), a radio network
controller (RNC), relay nodes, etc. The base station 114a and/or
the base station 114b may be configured to transmit and/or receive
wireless signals on one or more carrier frequencies, which may be
referred to as a cell (not shown). These frequencies may be in
licensed spectrum, unlicensed spectrum, or a combination of
licensed and unlicensed spectrum. A cell may provide coverage for a
wireless service to a specific geographical area that may be
relatively fixed or that may change over time. The cell may further
be divided into cell sectors. For example, the cell associated with
the base station 114a may be divided into three sectors. Thus, in
one embodiment, the base station 114a may include three
transceivers, i.e., one for each sector of the cell. In an
embodiment, the base station 114a may employ multiple-input
multiple output (MIMO) technology and may utilize multiple
transceivers for each sector of the cell. For example, beamforming
may be used to transmit and/or receive signals in desired spatial
directions.
[0166] The base stations 114a, 114b may communicate with one or
more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116,
which may be any suitable wireless communication link (e.g., radio
frequency (RF), microwave, centimeter wave, micrometer wave,
infrared (IR), ultraviolet (UV), visible light, etc.). The air
interface 116 may be established using any suitable radio access
technology (RAT).
[0167] More specifically, as noted above, the communications system
100 may be a multiple access system and may employ one or more
channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA,
and the like. For example, the base station 114a in the RAN 104/113
and the WTRUs 102a, 102b, 102c may implement a radio technology
such as Universal Mobile Telecommunications System (UMTS)
Terrestrial Radio Access (UTRA), which may establish the air
interface 115/116/117 using wideband CDMA (WCDMA). WCDMA may
include communication protocols such as High-Speed Packet Access
(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed
Downlink (DL) Packet Access (HSDPA) and/or High-Speed UL Packet
Access (HSUPA).
[0168] In an embodiment, the base station 114a and the WTRUs 102a,
102b, 102c may implement a radio technology such as Evolved UMTS
Terrestrial Radio Access (E-UTRA), which may establish the air
interface 116 using Long Term Evolution (LTE) and/or LTE-Advanced
(LTE-A) and/or LTE-Advanced Pro (LTE-A Pro).
[0169] In an embodiment, the base station 114a and the WTRUs 102a,
102b, 102c may implement a radio technology such as NR Radio
Access, which may establish the air interface 116 using New Radio
(NR).
[0170] In an embodiment, the base station 114a and the WTRUs 102a,
102b, 102c may implement multiple radio access technologies. For
example, the base station 114a and the WTRUs 102a, 102b, 102c may
implement LTE radio access and NR radio access together, for
instance using dual connectivity (DC) principles. Thus, the air
interface utilized by WTRUs 102a, 102b, 102c may be characterized
by multiple types of radio access technologies and/or transmissions
sent to/from multiple types of base stations (e.g., a eNB and a
gNB).
[0171] In other embodiments, the base station 114a and the WTRUs
102a, 102b, 102c may implement radio technologies such as IEEE
802.11 (i.e., Wireless Fidelity (WiFi), IEEE 802.16 (i.e.,
Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,
CDMA2000 1.times., CDMA2000 EV-DO, Interim Standard 2000 (IS-2000),
Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global
System for Mobile communications (GSM), Enhanced Data rates for GSM
Evolution (EDGE), GSM EDGE (GERAN), and the like.
[0172] The base station 114b in FIG. 33A may be a wireless router,
Home Node B, Home eNode B, or access point, for example, and may
utilize any suitable RAT for facilitating wireless connectivity in
a localized area, such as a place of business, a home, a vehicle, a
campus, an industrial facility, an air corridor (e.g., for use by
drones), a roadway, and the like. In one embodiment, the base
station 114b and the WTRUs 102c, 102d may implement a radio
technology such as IEEE 802.11 to establish a wireless local area
network (WLAN). In an embodiment, the base station 114b and the
WTRUs 102c, 102d may implement a radio technology such as IEEE
802.15 to establish a wireless personal area network (WPAN). In yet
another embodiment, the base station 114b and the WTRUs 102c, 102d
may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,
LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. As
shown in FIG. 33A, the base station 114b may have a direct
connection to the Internet 110. Thus, the base station 114b may not
be required to access the Internet 110 via the CN 106/115.
[0173] The RAN 104/113 may be in communication with the CN 106/115,
which may be any type of network configured to provide voice, data,
applications, and/or voice over internet protocol (VoIP) services
to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may
have varying quality of service (QoS) requirements, such as
differing throughput requirements, latency requirements, error
tolerance requirements, reliability requirements, data throughput
requirements, mobility requirements, and the like. The CN 106/115
may provide call control, billing services, mobile location-based
services, pre-paid calling, Internet connectivity, video
distribution, etc., and/or perform high-level security functions,
such as user authentication. Although not shown in FIG. 33A, it
will be appreciated that the RAN 104/113 and/or the CN 106/115 may
be in direct or indirect communication with other RANs that employ
the same RAT as the RAN 104/113 or a different RAT. For example, in
addition to being connected to the RAN 104/113, which may be
utilizing a NR radio technology, the CN 106/115 may also be in
communication with another RAN (not shown) employing a GSM, UMTS,
CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.
[0174] The CN 106/115 may also serve as a gateway for the WTRUs
102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110,
and/or the other networks 112. The PSTN 108 may include
circuit-switched telephone networks that provide plain old
telephone service (POTS). The Internet 110 may include a global
system of interconnected computer networks and devices that use
common communication protocols, such as the transmission control
protocol (TCP), user datagram protocol (UDP) and/or the internet
protocol (IP) in the TCP/IP internet protocol suite. The networks
112 may include wired and/or wireless communications networks owned
and/or operated by other service providers. For example, the
networks 112 may include another CN connected to one or more RANs,
which may employ the same RAT as the RAN 104/113 or a different
RAT.
[0175] Some or all of the WTRUs 102a, 102b, 102c, 102d in the
communications system 100 may include multi-mode capabilities
(e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple
transceivers for communicating with different wireless networks
over different wireless links). For example, the WTRU 102c shown in
FIG. 33A may be configured to communicate with the base station
114a, which may employ a cellular-based radio technology, and with
the base station 114b, which may employ an IEEE 802 radio
technology.
[0176] FIG. 33B is a system diagram illustrating an example WTRU
102. As shown in FIG. 33B, the WTRU 102 may include a processor
118, a transceiver 120, a transmit/receive element 122, a
speaker/microphone 124, a keypad 126, a display/touchpad 128,
non-removable memory 130, removable memory 132, a power source 134,
a global positioning system (GPS) chipset 136, and/or other
peripherals 138, among others. It will be appreciated that the WTRU
102 may include any sub-combination of the foregoing elements while
remaining consistent with an embodiment.
[0177] The processor 118 may be a general purpose processor, a
special purpose processor, a conventional processor, a digital
signal processor (DSP), a plurality of microprocessors, one or more
microprocessors in association with a DSP core, a controller, a
microcontroller, Application Specific Integrated Circuits (ASICs),
Field Programmable Gate Arrays (FPGAs) circuits, any other type of
integrated circuit (IC), a state machine, and the like. The
processor 118 may perform signal coding, data processing, power
control, input/output processing, and/or any other functionality
that enables the WTRU 102 to operate in a wireless environment. The
processor 118 may be coupled to the transceiver 120, which may be
coupled to the transmit/receive element 122. While FIG. 33B depicts
the processor 118 and the transceiver 120 as separate components,
it will be appreciated that the processor 118 and the transceiver
120 may be integrated together in an electronic package or
chip.
[0178] The transmit/receive element 122 may be configured to
transmit signals to, or receive signals from, a base station (e.g.,
the base station 114a) over the air interface 116. For example, in
one embodiment, the transmit/receive element 122 may be an antenna
configured to transmit and/or receive RF signals. In an embodiment,
the transmit/receive element 122 may be an emitter/detector
configured to transmit and/or receive IR, UV, or visible light
signals, for example. In yet another embodiment, the
transmit/receive element 122 may be configured to transmit and/or
receive both RF and light signals. It will be appreciated that the
transmit/receive element 122 may be configured to transmit and/or
receive any combination of wireless signals.
[0179] Although the transmit/receive element 122 is depicted in
FIG. 33B as a single element, the WTRU 102 may include any number
of transmit/receive elements 122. More specifically, the WTRU 102
may employ MIMO technology. Thus, in one embodiment, the WTRU 102
may include two or more transmit/receive elements 122 (e.g.,
multiple antennas) for transmitting and receiving wireless signals
over the air interface 116.
[0180] The transceiver 120 may be configured to modulate the
signals that are to be transmitted by the transmit/receive element
122 and to demodulate the signals that are received by the
transmit/receive element 122. As noted above, the WTRU 102 may have
multi-mode capabilities. Thus, the transceiver 120 may include
multiple transceivers for enabling the WTRU 102 to communicate via
multiple RATs, such as NR and IEEE 802.11, for example.
[0181] The processor 118 of the WTRU 102 may be coupled to, and may
receive user input data from, the speaker/microphone 124, the
keypad 126, and/or the display/touchpad 128 (e.g., a liquid crystal
display (LCD) display unit or organic light-emitting diode (OLED)
display unit). The processor 118 may also output user data to the
speaker/microphone 124, the keypad 126, and/or the display/touchpad
128. In addition, the processor 118 may access information from,
and store data in, any type of suitable memory, such as the
non-removable memory 130 and/or the removable memory 132. The
non-removable memory 130 may include random-access memory (RAM),
read-only memory (ROM), a hard disk, or any other type of memory
storage device. The removable memory 132 may include a subscriber
identity module (SIM) card, a memory stick, a secure digital (SD)
memory card, and the like. In other embodiments, the processor 118
may access information from, and store data in, memory that is not
physically located on the WTRU 102, such as on a server or a home
computer (not shown).
[0182] The processor 118 may receive power from the power source
134, and may be configured to distribute and/or control the power
to the other components in the WTRU 102. The power source 134 may
be any suitable device for powering the WTRU 102. For example, the
power source 134 may include one or more dry cell batteries (e.g.,
nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride
(NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and
the like.
[0183] The processor 118 may also be coupled to the GPS chipset
136, which may be configured to provide location information (e.g.,
longitude and latitude) regarding the current location of the WTRU
102. In addition to, or in lieu of, the information from the GPS
chipset 136, the WTRU 102 may receive location information over the
air interface 116 from a base station (e.g., base stations 114a,
114b) and/or determine its location based on the timing of the
signals being received from two or more nearby base stations. It
will be appreciated that the WTRU 102 may acquire location
information by way of any suitable location-determination method
while remaining consistent with an embodiment.
[0184] The processor 118 may further be coupled to other
peripherals 138, which may include one or more software and/or
hardware modules that provide additional features, functionality
and/or wired or wireless connectivity. For example, the peripherals
138 may include an accelerometer, an e-compass, a satellite
transceiver, a digital camera (for photographs and/or video), a
universal serial bus (USB) port, a vibration device, a television
transceiver, a hands free headset, a Bluetooth.RTM. module, a
frequency modulated (FM) radio unit, a digital music player, a
media player, a video game player module, an Internet browser, a
Virtual Reality and/or Augmented Reality (VR/AR) device, an
activity tracker, and the like. The peripherals 138 may include one
or more sensors, the sensors may be one or more of a gyroscope, an
accelerometer, a hall effect sensor, a magnetometer, an orientation
sensor, a proximity sensor, a temperature sensor, a time sensor; a
geolocation sensor; an altimeter, a light sensor, a touch sensor, a
magnetometer, a barometer, a gesture sensor, a biometric sensor,
and/or a humidity sensor.
[0185] The WTRU 102 may include a full duplex radio for which
transmission and reception of some or all of the signals (e.g.,
associated with particular subframes for both the UL (e.g., for
transmission) and downlink (e.g., for reception) may be concurrent
and/or simultaneous. The full duplex radio may include an
interference management unit to reduce and or substantially
eliminate self-interference via either hardware (e.g., a choke) or
signal processing via a processor (e.g., a separate processor (not
shown) or via processor 118). In an embodiment, the WRTU 102 may
include a half-duplex radio for which transmission and reception of
some or all of the signals (e.g., associated with particular
subframes for either the UL (e.g., for transmission) or the
downlink (e.g., for reception)).
[0186] FIG. 33C is a system diagram illustrating the RAN 104 and
the CN 106 according to an embodiment. As noted above, the RAN 104
may employ an E-UTRA radio technology to communicate with the WTRUs
102a, 102b, 102c over the air interface 116. The RAN 104 may also
be in communication with the CN 106.
[0187] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it
will be appreciated that the RAN 104 may include any number of
eNode-Bs while remaining consistent with an embodiment. The
eNode-Bs 160a, 160b, 160c may each include one or more transceivers
for communicating with the WTRUs 102a, 102b, 102c over the air
interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may
implement MIMO technology. Thus, the eNode-B 160a, for example, may
use multiple antennas to transmit wireless signals to, and/or
receive wireless signals from, the WTRU 102a.
[0188] Each of the eNode-Bs 160a, 160b, 160c may be associated with
a particular cell (not shown) and may be configured to handle radio
resource management decisions, handover decisions, scheduling of
users in the UL and/or DL, and the like. As shown in FIG. 33C, the
eNode-Bs 160a, 160b, 160c may communicate with one another over an
X2 interface.
[0189] The CN 106 shown in FIG. 33C may include a mobility
management entity (MME) 162, a serving gateway (SGW) 164, and a
packet data network (PDN) gateway (or PGW) 166. While each of the
foregoing elements are depicted as part of the CN 106, it will be
appreciated that any of these elements may be owned and/or operated
by an entity other than the CN operator.
[0190] The MME 162 may be connected to each of the eNode-Bs 162a,
162b, 162c in the RAN 104 via an S1 interface and may serve as a
control node. For example, the MME 162 may be responsible for
authenticating users of the WTRUs 102a, 102b, 102c, bearer
activation/deactivation, selecting a particular serving gateway
during an initial attach of the WTRUs 102a, 102b, 102c, and the
like. The MME 162 may provide a control plane function for
switching between the RAN 104 and other RANs (not shown) that
employ other radio technologies, such as GSM and/or WCDMA.
[0191] The SGW 164 may be connected to each of the eNode Bs 160a,
160b, 160c in the RAN 104 via the S1 interface. The SGW 164 may
generally route and forward user data packets to/from the WTRUs
102a, 102b, 102c. The SGW 164 may perform other functions, such as
anchoring user planes during inter-eNode B handovers, triggering
paging when DL data is available for the WTRUs 102a, 102b, 102c,
managing and storing contexts of the WTRUs 102a, 102b, 102c, and
the like.
[0192] The SGW 164 may be connected to the PGW 166, which may
provide the WTRUs 102a, 102b, 102c with access to packet-switched
networks, such as the Internet 110, to facilitate communications
between the WTRUs 102a, 102b, 102c and IP-enabled devices.
[0193] The CN 106 may facilitate communications with other
networks. For example, the CN 106 may provide the WTRUs 102a, 102b,
102c with access to circuit-switched networks, such as the PSTN
108, to facilitate communications between the WTRUs 102a, 102b,
102c and traditional land-line communications devices. For example,
the ON 106 may include, or may communicate with, an IP gateway
(e.g., an IP multimedia subsystem (IMS) server) that serves as an
interface between the CN 106 and the PSTN 108. In addition, the CN
106 may provide the WTRUs 102a, 102b, 102c with access to the other
networks 112, which may include other wired and/or wireless
networks that are owned and/or operated by other service
providers.
[0194] Although the WTRU is described in FIGS. 33A-33D as a
wireless terminal, it is contemplated that in certain
representative embodiments that such a terminal may use (e.g.,
temporarily or permanently) wired communication interfaces with the
communication network.
[0195] In representative embodiments, the other network 112 may be
a WLAN.
[0196] A WLAN in Infrastructure Basic Service Set (BSS) mode may
have an Access Point (AP) for the BSS and one or more stations
(STAs) associated with the AP. The AP may have an access or an
interface to a Distribution System (DS) or another type of
wired/wireless network that carries traffic in to and/or out of the
BSS. Traffic to STAs that originates from outside the BSS may
arrive through the AP and may be delivered to the STAs. Traffic
originating from STAs to destinations outside the BSS may be sent
to the AP to be delivered to respective destinations. Traffic
between STAs within the BSS may be sent through the AP, for
example, where the source STA may send traffic to the AP and the AP
may deliver the traffic to the destination STA. The traffic between
STAs within a BSS may be considered and/or referred to as
peer-to-peer traffic. The peer-to-peer traffic may be sent between
(e.g., directly between) the source and destination STAs with a
direct link setup (DLS). In certain representative embodiments, the
DLS may use an 802.11e DLS or an 802.11z tunneled DLS (TDLS). A
WLAN using an Independent BSS (IBSS) mode may not have an AP, and
the STAs (e.g., all of the STAs) within or using the IBSS may
communicate directly with each other. The IBSS mode of
communication may sometimes be referred to herein as an "ad-hoc"
mode of communication.
[0197] When using the 802.11 ac infrastructure mode of operation or
a similar mode of operations, the AP may transmit a beacon on a
fixed channel, such as a primary channel. The primary channel may
be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set
width via signaling. The primary channel may be the operating
channel of the BSS and may be used by the STAs to establish a
connection with the AP. In certain representative embodiments,
Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)
may be implemented, for example in in 802.11 systems. For CSMA/CA,
the STAs (e.g., every STA), including the AP, may sense the primary
channel. If the primary channel is sensed/detected and/or
determined to be busy by a particular STA, the particular STA may
back off. One STA (e.g., only one station) may transmit at any
given time in a given BSS.
[0198] High Throughput (HT) STAs may use a 40 MHz wide channel for
communication, for example, via a combination of the primary 20 MHz
channel with an adjacent or nonadjacent 20 MHz channel to form a 40
MHz wide channel.
[0199] Very High Throughput (VHT) STAs may support 20 MHz, 40 MHz,
80 MHz, and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz,
channels may be formed by combining contiguous 20 MHz channels. A
160 MHz channel may be formed by combining 8 contiguous 20 MHz
channels, or by combining two non-contiguous 80 MHz channels, which
may be referred to as an 80+80 configuration. For the 80+80
configuration, the data, after channel encoding, may be passed
through a segment parser that may divide the data into two streams.
Inverse Fast Fourier Transform (IFFT) processing, and time domain
processing, may be done on each stream separately. The streams may
be mapped on to the two 80 MHz channels, and the data may be
transmitted by a transmitting STA. At the receiver of the receiving
STA, the above described operation for the 80+80 configuration may
be reversed, and the combined data may be sent to the Medium Access
Control (MAC).
[0200] Sub 1 GHz modes of operation are supported by 802.11af and
802.11ah. The channel operating bandwidths, and carriers, are
reduced in 802.11 af and 802.11 ah relative to those used in
802.11n, and 802.11ac. 802.11af supports 5 MHz, 10 MHz and 20 MHz
bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah
supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using
non-TVWS spectrum. According to a representative embodiment,
802.11ah may support Meter Type Control/Machine-Type
Communications, such as MTC devices in a macro coverage area. MTC
devices may have certain capabilities, for example, limited
capabilities including support for (e.g., only support for) certain
and/or limited bandwidths. The MTC devices may include a battery
with a battery life above a threshold (e.g., to maintain a very
long battery life).
[0201] WLAN systems, which may support multiple channels, and
channel bandwidths, such as 802.11n, 802.11 ac, 802.11 af, and
802.11 ah, include a channel which may be designated as the primary
channel. The primary channel may have a bandwidth equal to the
largest common operating bandwidth supported by all STAs in the
BSS. The bandwidth of the primary channel may be set and/or limited
by a STA, from among all STAs in operating in a BSS, which supports
the smallest bandwidth operating mode. In the example of 802.11 ah,
the primary channel may be 1 MHz wide for STAs (e.g., MTC type
devices) that support (e.g., only support) a 1 MHz mode, even if
the AP, and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16
MHz, and/or other channel bandwidth operating modes. Carrier
sensing and/or Network Allocation Vector (NAV) settings may depend
on the status of the primary channel. If the primary channel is
busy, for example, due to a STA (which supports only a 1 MHz
operating mode), transmitting to the AP, the entire available
frequency bands may be considered busy even though a majority of
the frequency bands remains idle and may be available.
[0202] In the United States, the available frequency bands, which
may be used by 802.11ah, are from 902 MHz to 928 MHz. In Korea, the
available frequency bands are from 917.5 MHz to 923.5 MHz. In
Japan, the available frequency bands are from 916.5 MHz to 927.5
MHz. The total bandwidth available for 802.11ah is 6 MHz to 26 MHz
depending on the country code.
[0203] FIG. 33D is a system diagram illustrating the RAN 113 and
the CN 115 according to an embodiment. As noted above, the RAN 113
may employ an NR radio technology to communicate with the WTRUs
102a, 102b, 102c over the air interface 116. The RAN 113 may also
be in communication with the CN 115.
[0204] The RAN 113 may include gNBs 180a, 180b, 180c, though it
will be appreciated that the RAN 113 may include any number of gNBs
while remaining consistent with an embodiment. The gNBs 180a, 180b,
180c may each include one or more transceivers for communicating
with the WTRUs 102a, 102b, 102c over the air interface 116. In one
embodiment, the gNBs 180a, 180b, 180c may implement MIMO
technology. For example, gNBs 180a, 108b may utilize beamforming to
transmit signals to and/or receive signals from the gNBs 180a,
180b, 180c. Thus, the gNB 180a, for example, may use multiple
antennas to transmit wireless signals to, and/or receive wireless
signals from, the WTRU 102a. In an embodiment, the gNBs 180a, 180b,
180c may implement carrier aggregation technology. For example, the
gNB 180a may transmit multiple component carriers to the WTRU 102a
(not shown). A subset of these component carriers may be on
unlicensed spectrum while the remaining component carriers may be
on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c
may implement Coordinated Multi-Point (CoMP) technology. For
example, WTRU 102a may receive coordinated transmissions from gNB
180a and gNB 180b (and/or gNB 180c).
[0205] The WTRUs 102a, 102b, 102c may communicate with gNBs 180a,
180b, 180c using transmissions associated with a scalable
numerology. For example, the OFDM symbol spacing and/or OFDM
subcarrier spacing may vary for different transmissions, different
cells, and/or different portions of the wireless transmission
spectrum. The WTRUs 102a, 102b, 102c may communicate with gNBs
180a, 180b, 180c using subframe or transmission time intervals
(TTIs) of various or scalable lengths (e.g., containing varying
number of OFDM symbols and/or lasting varying lengths of absolute
time).
[0206] The gNBs 180a, 180b, 180c may be configured to communicate
with the WTRUs 102a, 102b, 102c in a standalone configuration
and/or a non-standalone configuration. In the standalone
configuration, WTRUs 102a, 102b, 102c may communicate with gNBs
180a, 180b, 180c without also accessing other RANs (e.g., such as
eNode-Bs 160a, 160b, 160c). In the standalone configuration, WTRUs
102a, 102b, 102c may utilize one or more of gNBs 180a, 180b, 180c
as a mobility anchor point. In the standalone configuration, WTRUs
102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using
signals in an unlicensed band. In a non-standalone configuration
WTRUs 102a, 102b, 102c may communicate with/connect to gNBs 180a,
180b, 180c while also communicating with/connecting to another RAN
such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b,
102c may implement DC principles to communicate with one or more
gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c
substantially simultaneously. In the non-standalone configuration,
eNode-Bs 160a, 160b, 160c may serve as a mobility anchor for WTRUs
102a, 102b, 102c and gNBs 180a, 180b, 180c may provide additional
coverage and/or throughput for servicing WTRUs 102a, 102b,
102c.
[0207] Each of the gNBs 180a, 180b, 180c may be associated with a
particular cell (not shown) and may be configured to handle radio
resource management decisions, handover decisions, scheduling of
users in the UL and/or DL, support of network slicing, dual
connectivity, interworking between NR and E-UTRA, routing of user
plane data towards User Plane Function (UPF) 184a, 184b, routing of
control plane information towards Access and Mobility Management
Function (AMF) 182a, 182b and the like. As shown in FIG. 33D, the
gNBs 180a, 180b, 180c may communicate with one another over an Xn
interface.
[0208] The CN 115 shown in FIG. 33D may include at least one AMF
182a, 182b, at least one UPF 184a,184b, at least one Session
Management Function (SMF) 183a, 183b, and possibly a Data Network
(DN) 185a, 185b. While each of the foregoing elements are depicted
as part of the CN 115, it will be appreciated that any of these
elements may be owned and/or operated by an entity other than the
CN operator.
[0209] The AMF 182a, 182b may be connected to one or more of the
gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may
serve as a control node. For example, the AMF 182a, 182b may be
responsible for authenticating users of the ATRUs 102a, 102b, 102c,
support for network slicing (e.g., handling of different PDU
sessions with different requirements), selecting a particular SMF
183a, 183b, management of the registration area, termination of NAS
signaling, mobility management, and the like. Network slicing may
be used by the AMF 182a, 182b in order to customize CN support for
WTRUs 102a, 102b, 102c based on the types of services being
utilized WTRUs 102a, 102b, 102c. For example, different network
slices may be established for different use cases such as services
relying on ultra-reliable low latency (URLLC) access, services
relying on enhanced massive mobile broadband (eMBB) access,
services for machine type communication (MTC) access, and/or the
like. The AMF 162 may provide a control plane function for
switching between the RAN 113 and other RANs (not shown) that
employ other radio technologies, such as LTE, LTE-A, LTE-A Pro,
and/or non-3GPP access technologies such as WiFi.
[0210] The SMF 183a, 183b may be connected to an AMF 182a, 182b in
the CN 115 via an N11 interface. The SMF 183a, 183b may also be
connected to a UPF 184a, 184b in the CN 115 via an N4 interface.
The SMF 183a, 183b may select and control the UPF 184a, 184b and
configure the routing of traffic through the UPF 184a, 184b. The
SMF 183a, 183b may perform other functions, such as managing and
allocating UE IP address, managing PDU sessions, controlling policy
enforcement and QoS, providing downlink data notifications, and the
like. A PDU session type may be IP-based, non-IP based,
Ethernet-based, and the like.
[0211] The UPF 184a, 184b may be connected to one or more of the
gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, which may
provide the WTRUs 102a, 102b, 102c with access to packet-switched
networks, such as the Internet 110, to facilitate communications
between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF
184, 184b may perform other functions, such as routing and
forwarding packets, enforcing user plane policies, supporting
multi-homed PDU sessions, handling user plane QoS, buffering
downlink packets, providing mobility anchoring, and the like.
[0212] The CN 115 may facilitate communications with other
networks. For example, the CN 115 may include, or may communicate
with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server)
that serves as an interface between the CN 115 and the PSTN 108. In
addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with
access to the other networks 112, which may include other wired
and/or wireless networks that are owned and/or operated by other
service providers. In one embodiment, the WTRUs 102a, 102b, 102c
may be connected to a local Data Network (DN) 185a, 185b through
the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and
an N6 interface between the UPF 184a, 184b and the DN 185a,
185b.
[0213] In view of FIGS. 33A-33D, and the corresponding description
of FIGS. 33A-33D, one or more, or all, of the functions described
herein with regard to one or more of: WTRU 102a-d, Base Station
114a-b, eNode-B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF
182a-b, UPF 184a-b, SMF 183a-b, DN 185a-b, and/or any other
device(s) described herein, may be performed by one or more
emulation devices (not shown). The emulation devices may be one or
more devices configured to emulate one or more, or all, of the
functions described herein. For example, the emulation devices may
be used to test other devices and/or to simulate network and/or
WTRU functions.
[0214] The emulation devices may be designed to implement one or
more tests of other devices in a lab environment and/or in an
operator network environment. For example, the one or more
emulation devices may perform the one or more, or all, functions
while being fully or partially implemented and/or deployed as part
of a wired and/or wireless communication network in order to test
other devices within the communication network. The one or more
emulation devices may perform the one or more, or all, functions
while being temporarily implemented/deployed as part of a wired
and/or wireless communication network. The emulation device may be
directly coupled to another device for purposes of testing and/or
may performing testing using over-the-air wireless
communications.
[0215] The one or more emulation devices may perform the one or
more, including all, functions while not being implemented/deployed
as part of a wired and/or wireless communication network. For
example, the emulation devices may be utilized in a testing
scenario in a testing laboratory and/or a non-deployed (e.g.,
testing) wired and/or wireless communication network in order to
implement testing of one or more components. The one or more
emulation devices may be test equipment. Direct RF coupling and/or
wireless communications via RF circuitry (e.g., which may include
one or more antennas) may be used by the emulation devices to
transmit and/or receive data.
* * * * *