U.S. patent application number 16/222626 was filed with the patent office on 2020-01-02 for method and apparatus for video coding.
This patent application is currently assigned to Tencent America LLC. The applicant listed for this patent is Tencent America LLC. Invention is credited to Guichun LI, Xiang LI, Shan LIU, Xiaozhong XU.
Application Number | 20200007864 16/222626 |
Document ID | / |
Family ID | 69008522 |
Filed Date | 2020-01-02 |
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United States Patent
Application |
20200007864 |
Kind Code |
A1 |
LI; Guichun ; et
al. |
January 2, 2020 |
METHOD AND APPARATUS FOR VIDEO CODING
Abstract
Aspects of the disclosure provide method and apparatus for video
encoding/decoding. In some examples, an apparatus for video
decoding includes receiving circuitry and processing circuitry. The
processing circuitry decodes prediction information for a block in
a current picture that is a part of a coded video bitstream. The
prediction information is indicative of an inter prediction mode.
In response to the inter prediction mode, the processing circuitry
constructs a candidate list of candidate motion vector predictors
in a ranking order that are sorted based on statistics of motion
information in a spatial neighboring region of the block. The
processing circuitry then determines, a motion vector predictor
from the candidate list following the ranking order, and
reconstructs samples of the block according to motion information
associated with the determined motion vector predictor.
Inventors: |
LI; Guichun; (Milpitas,
CA) ; XU; Xiaozhong; (State College, PA) ; LI;
Xiang; (Los Gatos, CA) ; LIU; Shan; (San Jose,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Tencent America LLC |
Palo Alto |
CA |
US |
|
|
Assignee: |
Tencent America LLC
Palo Alto
CA
|
Family ID: |
69008522 |
Appl. No.: |
16/222626 |
Filed: |
December 17, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62693055 |
Jul 2, 2018 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04N 19/176 20141101;
H04N 19/105 20141101; H04N 19/52 20141101; H04N 19/44 20141101;
H04N 19/139 20141101; H04N 19/129 20141101 |
International
Class: |
H04N 19/129 20060101
H04N019/129; H04N 19/44 20060101 H04N019/44; H04N 19/139 20060101
H04N019/139; H04N 19/105 20060101 H04N019/105; H04N 19/176 20060101
H04N019/176 |
Claims
1. A method for video decoding in a decoder, comprising: decoding
prediction information for a current block in a current picture
from a coded video bitstream, the prediction information being
indicative of an inter prediction mode; scanning a line of blocks
in a spatial neighboring region of the current block to collect
statistics of motion information in the spatial neighboring region,
the line of blocks including adjacent blocks to the current block
and at least one non-adjacent block to the current block;
constructing, in response to the inter prediction mode and if the
current block satisfies at least one of a width requirement and a
height requirement, a candidate list of candidate motion vector
predictors in a ranking order that are sorted based on the
statistics of the motion information in the spatial neighboring
region of the current block; determining a motion vector predictor
from the candidate list following the ranking order; and
reconstructing at least a sample of the current block according to
motion information associated with the determined motion vector
predictor.
2. The method of claim 1, wherein the scanning comprises: scanning
neighboring blocks in the spatial neighboring region to collect the
statistics of the motion information in the spatial neighboring
region.
3. The method of claim 1, wherein the scanning comprises: scanning
minimum-size blocks in the spatial neighboring region to collect
the statistics of the motion information in the spatial neighboring
region.
4. The method of claim 1, wherein the scanning comprises: scanning
minimum-size blocks that are adjacent to the current block to
collect the statistics of the motion information in the spatial
neighboring region.
5. The method of claim 1, wherein the scanning includes scanning
first minimum-size blocks that are located in a left column next to
the current block and are extended in a bottom-left direction; and
the method further includes scanning second minimum-size blocks
that are located in an upper row next to the current block and are
extended in an above-right direction to collect the statistics of
the motion information in the spatial neighboring region.
6. The method of claim 1, wherein the scanning includes scanning
first minimum-size blocks that are located in multiple left columns
next to the current block and are extended in a bottom-left
direction to collect the statistics of the motion information in
the spatial neighboring region; and the method further includes
scanning second minimum-size blocks that are located in multiple
upper rows next to the current block and are extended in an
above-right direction to collect the statistics of the motion
information in the spatial neighboring region.
7. The method of claim 1, wherein the scanning comprises: scanning
representative minimum-size blocks respectively in grid units that
are adjacent to the current block to collect the statistics of the
motion information in the spatial neighboring region.
8. The method of claim 1, wherein the scanning includes scanning
first representative minimum-size blocks respectively in first grid
units that are located in a left column next to the current block
and are extended in a bottom-left direction to collect the
statistics of the motion information in the spatial neighboring
region; and the method further includes scanning second
representative minimum-size blocks respectively in second grid
units that are located in an upper row next to the second block and
are extended in an above-right direction to collect the statistics
of the motion information in the spatial neighboring region.
9. The method of claim 1, wherein the scanning includes scanning
first representative minimum-size blocks respectively in first grid
units that are located in multiple left columns, including the line
of blocks, next to the current block and are extended in a
bottom-left direction to collect the statistics of the motion
information in the spatial neighboring region; and the method
further includes scanning second representative minimum-size blocks
respectively in second grid units that are located in multiple
upper rows next to the current block and are extended in an
above-right direction to collect the statistics of the motion
information in the spatial neighboring region.
10. The method of claim 2, further comprising: constructing a
histogram of the motion information in the spatial neighboring
region according to the statistics; and sorting motion vector
predictors from the spatial neighboring region into the ranking
order according to the histogram.
11. The method of claim 10, further comprising: constructing the
histogram with bins corresponding to individual motion vectors.
12. The method of claim 10, further comprising: constructing the
histogram with bins corresponding to ranges of motion vectors.
13. The method of claim 10, further comprising: selecting a portion
of the sorted motion vector predictors based on rankings in the
ranking order.
14. (canceled)
15. An apparatus for video decoding, comprising: processing
circuitry configured to: decode prediction information for a
current block in a current picture from a coded video bitstream,
the prediction information being indicative of an inter prediction
mode; scan a line of blocks in a spatial neighboring region of the
current block to collect statistics of motion information in the
spatial neighboring region, the line of blocks including adjacent
blocks to the current block and at least one non-adjacent block to
the current block; construct, in response to the inter prediction
mode and if the current block satisfies at least one of a width
requirement and a height requirement, a candidate list of candidate
motion vector predictors in a ranking order that are sorted based
on the statistics of the motion information in the spatial
neighboring region of the current block; determine a motion vector
predictor from the candidate list following the ranking order; and
reconstruct at least a sample of the current block according to
motion information associated with the determined motion vector
predictor.
16. The apparatus of claim 15, wherein the processing circuitry is
further configured to: perform the scan on neighboring blocks in
the spatial neighboring region to collect the statistics of the
motion information in the spatial neighboring region.
17. The apparatus of claim 6, wherein the processing circuitry is
further configured to: perform the scan on minimum-size blocks in
the spatial neighboring region to collect the statistics of the
motion information in the spatial neighboring region.
18. The apparatus of claim 16, wherein the processing circuitry is
further configured to: construct a histogram of the motion
information in the spatial neighboring region according to the
statistics; and sort motion vector predictors from the spatial
neighboring region into the ranking order according to the
histogram.
19. The apparatus of claim 18, wherein the processing circuitry is
further configured to: select a portion of the sorted motion vector
predictors based on rankings in the ranking order to construct the
candidate list.
20. (canceled)
Description
INCORPORATION BY REFERENCE
[0001] This present disclosure claims the benefit of priority to
U.S. Provisional Application No. 62/693,055, "METHODS FOR
RANKING-BASED SPATIAL MERGE CANDIDATE LIST FOR INTERPICTURE
PREDICTION" filed on Jul. 2, 2018, which is incorporated by
reference herein in its entirety.
TECHNICAL FIELD
[0002] The present disclosure describes embodiments generally
related to video coding.
BACKGROUND
[0003] The background description provided herein is for the
purpose of generally presenting the context of the disclosure. Work
of the presently named inventors, to the extent the work is
described in this background section, as well as aspects of the
description that may not otherwise qualify as prior art at the time
of filing, are neither expressly nor impliedly admitted as prior
art against the present disclosure.
[0004] Video coding and decoding can be performed using
inter-picture prediction with motion compensation. Uncompressed
digital video can include a series of pictures, each picture having
a spatial dimension of, for example, 1920.times.1080 luminance
samples and associated chrominance samples. The series of pictures
can have a fixed or variable picture rate (informally also known as
frame rate), of, for example 60 pictures per second or 60 Hz.
Uncompressed video has significant bitrate requirements. For
example, 1080p60 4:2:0 video at 8 bit per sample (1920.times.1080
luminance sample resolution at 60 Hz frame rate) requires close to
1.5 Gbit/s bandwidth. An hour of such video requires more than 600
GBytes of storage space.
[0005] One purpose of video coding and decoding can be the
reduction of redundancy in the input video signal, through
compression. Compression can help reduce the aforementioned
bandwidth or storage space requirements, in some cases by two
orders of magnitude or more. Both lossless and lossy compression,
as well as a combination thereof can be employed. Lossless
compression refers to techniques where an exact copy of the
original signal can be reconstructed from the compressed original
signal. When using lossy compression, the reconstructed signal may
not be identical to the original signal, but the distortion between
original and reconstructed signals is small enough to make the
reconstructed signal useful for the intended application. In the
case of video, lossy compression is widely employed. The amount of
distortion tolerated depends on the application; for example, users
of certain consumer streaming applications may tolerate higher
distortion than users of television distribution applications. The
compression ratio achievable can reflect that: higher
allowable/tolerable distortion can yield higher compression
ratios.
[0006] Motion compensation can be a lossy compression technique and
can relate to techniques where a block of sample data from a
previously reconstructed picture or part thereof (reference
picture), after being spatially shifted in a direction indicated by
a motion vector (MV henceforth), is used for the prediction of a
newly reconstructed picture or picture part. In some cases, the
reference picture can be the same as the picture currently under
reconstruction. MVs can have two dimensions X and Y, or three
dimensions, the third being an indication of the reference picture
in use (the latter, indirectly, can be a time dimension).
[0007] In some video compression techniques, an MV applicable to a
certain area of sample data can be predicted from other MVs, for
example from those related to another area of sample data spatially
adjacent to the area under reconstruction, and preceding that MV in
decoding order. Doing so can substantially reduce the amount of
data required for coding the MV, thereby removing redundancy and
increasing compression. MV prediction can work effectively, for
example, because when coding an input video signal derived from a
camera (known as natural video) there is a statistical likelihood
that areas larger than the area to which a single MV is applicable
move in a similar direction and, therefore, can in some cases be
predicted using a similar motion vector derived from MVs of
neighboring area. That results in the MV found for a given area to
be similar or the same as the MV predicted from the surrounding
MVs, and that in turn can be represented, after entropy coding, in
a smaller number of bits than what would be used if coding the MV
directly. In some cases, MV prediction can be an example of
lossless compression of a signal (namely: the MVs) derived from the
original signal (namely: the sample stream). In other cases, MV
prediction itself can be lossy, for example because of rounding
errors when calculating a predictor from several surrounding
MVs.
[0008] Various MV prediction mechanisms are described in H.265/HEVC
(ITU-T Rec. H.265, "High Efficiency Video Coding", December 2016).
Out of the many MV prediction mechanisms that H.265 offers,
described here is a technique henceforth referred to as "spatial
merge".
[0009] Referring to FIG. 1, a current block (101) comprises samples
that have been found by the encoder during the motion search
process to be predictable from a previous block of the same size
that has been spatially shifted. Instead of coding that MV
directly, the MV can be derived from metadata associated with one
or more reference pictures, for example from the most recent (in
decoding order) reference picture, using the MV associated with
either one of five surrounding samples, denoted A0, A1, and B0, B1,
B2 (102 through 106, respectively). In H.265, the MV prediction can
use predictors from the same reference picture that the neighboring
block is using.
SUMMARY
[0010] Aspects of the disclosure provide method and apparatus for
video encoding/decoding. In some examples, an apparatus for video
decoding includes receiving circuitry and processing circuitry. The
processing circuitry decodes prediction information for a block in
a current picture that is a part of a coded video bitstream. The
prediction information is indicative of an inter prediction mode.
In response to the inter prediction mode, the processing circuitry
constructs a candidate list of candidate motion vector predictors
in a ranking order that are sorted based on statistics of motion
information in a spatial neighboring region of the block. The
processing circuitry then determines, a motion vector predictor
from the candidate list following the ranking order, and
reconstructs samples of the block according to motion information
associated with the determined motion vector predictor.
[0011] According to an aspect of the disclosure, the processing
circuitry scans neighboring blocks in the spatial neighboring
region to collect the statistics of the motion information in the
spatial neighboring region.
[0012] In an example, the processing circuitry scans minimum-size
blocks in the spatial neighboring region to collect the statistics
of the motion information in the spatial neighboring region. For
example, the processing circuitry scans minimum-size blocks that
are adjacent to the block to collect the statistics of the motion
information in the spatial neighboring region.
[0013] In an embodiment, the processing circuitry scans first
minimum-size blocks that are located in a left column next to the
block and are extended in a bottom-left direction to collect the
statistics of the motion information in the spatial neighboring
region, and scans second minimum-size blocks that are located in an
upper row next to the block and are extended in an above-right
direction to collect the statistics of the motion information in
the spatial neighboring region.
[0014] In another embodiment, the processing circuitry scans first
minimum-size blocks that are located in multiple left columns next
to the block and are extended in a bottom-left direction to collect
the statistics of the motion information in the spatial neighboring
region, and scans second minimum-size blocks that are located in
multiple upper rows next to the block and are extended in an
above-right direction to collect the statistics of the motion
information in the spatial neighboring region.
[0015] In another embodiment, the processing circuitry scans
representative minimum-size blocks respectively in grid units that
are adjacent to the block to collect the statistics of the motion
information in the spatial neighboring region.
[0016] In another embodiment, the processing circuitry scans first
representative minimum-size blocks respectively in first grid units
that are located in a left column next to the block and are
extended in a bottom-left direction to collect the statistics of
the motion information in the spatial neighboring region, and scans
second representative minimum-size blocks respectively in second
grid units that are located in an upper row next to the block and
are extended in an above-right direction to collect the statistics
of the motion information in the spatial neighboring region.
[0017] In another embodiment, the processing circuitry scans first
representative minimum-size blocks respectively in first grid units
that are located in multiple left columns next to the block and are
extended in a bottom-left direction to collect the statistics of
the motion information in the spatial neighboring region, and scans
second representative minimum-size blocks respectively in second
grid units that are located in multiple upper rows next to the
block and are extended in an above-right direction to collect the
statistics of the motion information in the spatial neighboring
region.
[0018] According to an aspect of the disclosure, the processing
circuitry constructs a histogram of the motion information in the
spatial neighboring region according to the statistics, and sorts
motion vector predictors from the spatial neighboring region into
the ranking order according to the histogram. In an embodiment, the
processing circuitry constructs the histogram with bins
corresponding to individual motion vectors. In another embodiment,
the processing circuitry constructs the histogram with bins
corresponding to ranges of motion vectors.
[0019] In some examples, the processing circuitry selects a portion
of sorted the motion vector predictors based on rankings in the
ranking order.
[0020] In some embodiments, the processing circuitry constructs the
candidate list of candidate motion vector predictors in the ranking
order when the block satisfies at least one of a width requirement
and a height requirement.
[0021] Aspects of the disclosure also provide a non-transitory
computer-readable medium storing instructions which when executed
by a computer for video decoding cause the computer to perform the
method for video decoding.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Further features, the nature, and various advantages of the
disclosed subject matter will be more apparent from the following
detailed description and the accompanying drawings in which:
[0023] FIG. 1 is a schematic illustration of a current block and
its surrounding spatial merge candidates in accordance with
H.265.
[0024] FIG. 2 is a schematic illustration of a simplified block
diagram of a communication system (200) in accordance with an
embodiment.
[0025] FIG. 3 is a schematic illustration of a simplified block
diagram of a communication system (300) in accordance with an
embodiment.
[0026] FIG. 4 is a schematic illustration of a simplified block
diagram of a decoder in accordance with an embodiment.
[0027] FIG. 5 is a schematic illustration of a simplified block
diagram of an encoder in accordance with an embodiment.
[0028] FIG. 6 shows a block diagram of an encoder in accordance
with another embodiment.
[0029] FIG. 7 shows a block diagram of a decoder in accordance with
another embodiment.
[0030] FIG. 8 shows an example of spatial and temporal candidates
in some examples.
[0031] FIG. 9 shows a diagram of potential spatial merge candidates
of a current block (910) according to an embodiment of the
disclosure.
[0032] FIG. 10 shows a diagram of potential merge candidates of a
current block (1010) according to another embodiment of the
disclosure.
[0033] FIG. 11 shows a diagram of potential merge candidates of a
current block (1110) according to another embodiment of the
disclosure.
[0034] FIG. 12 shows a diagram of potential merge candidates of a
current block (1210) according to another embodiment of the
disclosure.
[0035] FIG. 13 shows a diagram of potential merge candidates of a
current block (1310) according to another embodiment of the
disclosure.
[0036] FIG. 14 shows a diagram of potential merge candidates of a
current block (1410) according to another embodiment of the
disclosure.
[0037] FIG. 15 shows a flow chart outlining a process (1500)
according to an embodiment of the disclosure.
[0038] FIG. 16 is a schematic illustration of a computer system in
accordance with an embodiment.
DETAILED DESCRIPTION OF EMBODIMENTS
[0039] FIG. 2 illustrates a simplified block diagram of a
communication system (200) according to an embodiment of the
present disclosure. The communication system (200) includes a
plurality of terminal devices that can communicate with each other,
via, for example, a network (250). For example, the communication
system (200) includes a first pair of terminal devices (210) and
(220) interconnected via the network (250). In the FIG. 2 example,
the first pair of terminal devices (210) and (220) performs
unidirectional transmission of data. For example, the terminal
device (210) may code video data (e.g., a stream of video pictures
that are captured by the terminal device (210)) for transmission to
the other terminal device (220) via the network (250). The encoded
video data can be transmitted in the form of one or more coded
video bitstreams. The terminal device (220) may receive the coded
video data from the network (250), decode the coded video data to
recover the video pictures and display video pictures according to
the recovered video data. Unidirectional data transmission may be
common in media serving applications and the like.
[0040] In another example, the communication system (200) includes
a second pair of terminal devices (230) and (240) that performs
bidirectional transmission of coded video data that may occur, for
example, during videoconferencing. For bidirectional transmission
of data, in an example, each terminal device of the terminal
devices (230) and (240) may code video data (e.g., a stream of
video pictures that are captured by the terminal device) for
transmission to the other terminal device of the terminal devices
(230) and (240) via the network (250). Each terminal device of the
terminal devices (230) and (240) also may receive the coded video
data transmitted by the other terminal device of the terminal
devices (230) and (240), and may decode the coded video data to
recover the video pictures and may display video pictures at an
accessible display device according to the recovered video
data.
[0041] In the FIG. 2 example, the terminal devices (210), (220),
(230) and (240) may be illustrated as servers, personal computers
and smart phones but the principles of the present disclosure may
be not so limited. Embodiments of the present disclosure find
application with laptop computers, tablet computers, media players
and/or dedicated video conferencing equipment. The network (250)
represents any number of networks that convey coded video data
among the terminal devices (210), (220), (230) and (240), including
for example wireline (wired) and/or wireless communication
networks. The communication network (250) may exchange data in
circuit-switched and/or packet-switched channels. Representative
networks include telecommunications networks, local area networks,
wide area networks and/or the Internet. For the purposes of the
present discussion, the architecture and topology of the network
(250) may be immaterial to the operation of the present disclosure
unless explained herein below.
[0042] FIG. 3 illustrates, as an example for an application for the
disclosed subject matter, the placement of a video encoder and a
video decoder in a streaming environment. The disclosed subject
matter can be equally applicable to other video enabled
applications, including, for example, video conferencing, digital
TV, storing of compressed video on digital media including CD, DVD,
memory stick and the like, and so on.
[0043] A streaming system may include a capture subsystem (313),
that can include a video source (301), for example a digital
camera, creating for example a stream of video pictures (302) that
are uncompressed. In an example, the stream of video pictures (302)
includes samples that are taken by the digital camera. The stream
of video pictures (302), depicted as a bold line to emphasize a
high data volume when compared to encoded video data (304) (or
coded video bitstreams), can be processed by an electronic device
(320) that includes a video encoder (303) coupled to the video
source (301). The video encoder (303) can include hardware,
software, or a combination thereof to enable or implement aspects
of the disclosed subject matter as described in more detail below.
The encoded video data (304) (or encoded video bitstream (304)),
depicted as a thin line to emphasize the lower data volume when
compared to the stream of video pictures (302), can be stored on a
streaming server (305) for future use. One or more streaming client
subsystems, such as client subsystems (306) and (308) in FIG. 3 can
access the streaming server (305) to retrieve copies (307) and
(309) of the encoded video data (304). A client subsystem (306) can
include a video decoder (310), for example, in an electronic device
(330). The video decoder (310) decodes the incoming copy (307) of
the encoded video data and creates an outgoing stream of video
pictures (311) that can be rendered on a display (312) (e.g.,
display screen) or other rendering device (not depicted). In some
streaming systems, the encoded video data (304), (307), and (309)
(e.g., video bitstreams) can be encoded according to certain video
coding/compression standards. Examples of those standards include
ITU-T Recommendation H.265. In an example, a video coding standard
under development is informally known as Versatile Video Coding
(VVC). The disclosed subject matter may be used in the context of
VVC.
[0044] It is noted that the electronic devices (320) and (330) can
include other components (not shown). For example, the electronic
device (320) can include a video decoder (not shown) and the
electronic device (330) can include a video encoder (not shown) as
well.
[0045] FIG. 4 shows a block diagram of a video decoder (410)
according to an embodiment of the present disclosure. The video
decoder (410) can be included in an electronic device (430). The
electronic device (430) can include a receiver (431) (e.g.,
receiving circuitry). The video decoder (410) can be used in the
place of the video decoder (310) in the FIG. 3 example.
[0046] The receiver (431) may receive one or more coded video
sequences to be decoded by the video decoder (410); in the same or
another embodiment, one coded video sequence at a time, where the
decoding of each coded video sequence is independent from other
coded video sequences. The coded video sequence may be received
from a channel (401), which may be a hardware/software link to a
storage device which stores the encoded video data. The receiver
(431) may receive the encoded video data with other data, for
example, coded audio data and/or ancillary data streams, that may
be forwarded to their respective using entities (not depicted). The
receiver (431) may separate the coded video sequence from the other
data. To combat network jitter, a buffer memory (415) may be
coupled in between the receiver (431) and an entropy decoder/parser
(420) ("parser (420)" henceforth). In certain applications, the
buffer memory (415) is part of the video decoder (410). In others,
it can be outside of the video decoder (410) (not depicted). In
still others, there can be a buffer memory (not depicted) outside
of the video decoder (410), for example to combat network jitter,
and in addition another buffer memory (415) inside the video
decoder (410), for example to handle playout timing. When the
receiver (431) is receiving data from a store/forward device of
sufficient bandwidth and controllability, or from an isosynchronous
network, the buffer memory (415) may not be needed, or can be
small. For use on best effort packet networks such as the Internet,
the buffer memory (415) may be required, can be comparatively large
and can be advantageously of adaptive size, and may at least
partially be implemented in an operating system or similar elements
(not depicted) outside of the video decoder (410).
[0047] The video decoder (410) may include the parser (420) to
reconstruct symbols (421) from the coded video sequence. Categories
of those symbols include information used to manage operation of
the video decoder (410), and potentially information to control a
rendering device such as a render device (412) (e.g., a display
screen) that is not an integral part of the electronic device (430)
but can be coupled to the electronic device (430), as was shown in
FIG. 4. The control information for the rendering device(s) may be
in the form of Supplemental Enhancement Information (SEI messages)
or Video Usability Information (VUI) parameter set fragments (not
depicted). The parser (420) may parse/entropy-decode the coded
video sequence that is received. The coding of the coded video
sequence can be in accordance with a video coding technology or
standard, and can follow various principles, including variable
length coding, Huffman coding, arithmetic coding with or without
context sensitivity, and so forth. The parser (420) may extract
from the coded video sequence, a set of subgroup parameters for at
least one of the subgroups of pixels in the video decoder, based
upon at least one parameter corresponding to the group. Subgroups
can include Groups of Pictures (GOPs), pictures, tiles, slices,
macroblocks, Coding Units (CUs), blocks, Transform Units (TUs),
Prediction Units (PUs) and so forth. The parser (420) may also
extract from the coded video sequence information such as transform
coefficients, quantizer parameter values, motion vectors, and so
forth.
[0048] The parser (420) may perform an entropy decoding/parsing
operation on the video sequence received from the buffer memory
(415), so as to create symbols (421).
[0049] Reconstruction of the symbols (421) can involve multiple
different units depending on the type of the coded video picture or
parts thereof (such as: inter and intra picture, inter and intra
block), and other factors. Which units are involved, and how, can
be controlled by the subgroup control information that was parsed
from the coded video sequence by the parser (420). The flow of such
subgroup control information between the parser (420) and the
multiple units below is not depicted for clarity.
[0050] Beyond the functional blocks already mentioned, the video
decoder (410) can be conceptually subdivided into a number of
functional units as described below. In a practical implementation
operating under commercial constraints, many of these units
interact closely with each other and can, at least partly, be
integrated into each other. However, for the purpose of describing
the disclosed subject matter, the conceptual subdivision into the
functional units below is appropriate.
[0051] A first unit is the scaler/inverse transform unit (451). The
scaler/inverse transform unit (451) receives a quantized transform
coefficient as well as control information, including which
transform to use, block size, quantization factor, quantization
scaling matrices, etc. as symbol(s) (421) from the parser (420).
The scaler/inverse transform unit (451) can output blocks
comprising sample values, that can be input into aggregator
(455).
[0052] In some cases, the output samples of the scaler/inverse
transform (451) can pertain to an intra coded block; that is: a
block that is not using predictive information from previously
reconstructed pictures, but can use predictive information from
previously reconstructed parts of the current picture. Such
predictive information can be provided by an intra picture
prediction unit (452). In some cases, the intra picture prediction
unit (452) generates a block of the same size and shape of the
block under reconstruction, using surrounding already reconstructed
information fetched from the current picture buffer (458). The
current picture buffer (458) buffers, for example, partly
reconstructed current picture and/or fully reconstructed current
picture. The aggregator (455), in some cases, adds, on a per sample
basis, the prediction information the intra prediction unit (452)
has generated to the output sample information as provided by the
scaler/inverse transform unit (451).
[0053] In other cases, the output samples of the scaler/inverse
transform unit (451) can pertain to an inter coded, and potentially
motion compensated block. In such a case, a motion compensation
prediction unit (453) can access reference picture memory (457) to
fetch samples used for prediction. After motion compensating the
fetched samples in accordance with the symbols (421) pertaining to
the block, these samples can be added by the aggregator (455) to
the output of the scaler/inverse transform unit (451) (in this case
called the residual samples or residual signal) so as to generate
output sample information. The addresses within the reference
picture memory (457) from where the motion compensation prediction
unit (453) fetches prediction samples can be controlled by motion
vectors, available to the motion compensation prediction unit (453)
in the form of symbols (421) that can have, for example X, Y, and
reference picture components. Motion compensation also can include
interpolation of sample values as fetched from the reference
picture memory (457) when sub-sample exact motion vectors are in
use, motion vector prediction mechanisms, and so forth.
[0054] The output samples of the aggregator (455) can be subject to
various loop filtering techniques in the loop filter unit (456).
Video compression technologies can include in-loop filter
technologies that are controlled by parameters included in the
coded video sequence (also referred to as coded video bitstream)
and made available to the loop filter unit (456) as symbols (421)
from the parser (420), but can also be responsive to
meta-information obtained during the decoding of previous (in
decoding order) parts of the coded picture or coded video sequence,
as well as responsive to previously reconstructed and loop-filtered
sample values.
[0055] The output of the loop filter unit (456) can be a sample
stream that can be output to the render device (412) as well as
stored in the reference picture memory (457) for use in future
inter-picture prediction.
[0056] Certain coded pictures, once fully reconstructed, can be
used as reference pictures for future prediction. For example, once
a coded picture corresponding to a current picture is fully
reconstructed and the coded picture has been identified as a
reference picture (by, for example, the parser (420)), the current
picture buffer (458) can become a part of the reference picture
memory (457), and a fresh current picture buffer can be reallocated
before commencing the reconstruction of the following coded
picture.
[0057] The video decoder (410) may perform decoding operations
according to a predetermined video compression technology in a
standard, such as ITU-T Rec. H.265. The coded video sequence may
conform to a syntax specified by the video compression technology
or standard being used, in the sense that the coded video sequence
adheres to both the syntax of the video compression technology or
standard and the profiles as documented in the video compression
technology or standard. Specifically, a profile can select certain
tools as the only tools available for use under that profile from
all the tools available in the video compression technology or
standard. Also necessary for compliance can be that the complexity
of the coded video sequence is within bounds as defined by the
level of the video compression technology or standard. In some
cases, levels restrict the maximum picture size, maximum frame
rate, maximum reconstruction sample rate (measured in, for example
megasamples per second), maximum reference picture size, and so on.
Limits set by levels can, in some cases, be further restricted
through Hypothetical Reference Decoder (HRD) specifications and
metadata for HRD buffer management signaled in the coded video
sequence.
[0058] In an embodiment, the receiver (431) may receive additional
(redundant) data with the encoded video. The additional data may be
included as part of the coded video sequence(s). The additional
data may be used by the video decoder (410) to properly decode the
data and/or to more accurately reconstruct the original video data.
Additional data can be in the form of, for example, temporal,
spatial, or signal noise ratio (SNR) enhancement layers, redundant
slices, redundant pictures, forward error correction codes, and so
on.
[0059] FIG. 5 shows a block diagram of a video encoder (503)
according to an embodiment of the present disclosure. The video
encoder (503) is included in an electronic device (520). The
electronic device (520) includes a transmitter (540) (e.g.,
transmitting circuitry). The video encoder (503) can be used in the
place of the video encoder (303) in the FIG. 3 example.
[0060] The video encoder (503) may receive video samples from a
video source (501) (that is not part of the electronic device (520)
in the FIG. 5 example) that may capture video image(s) to be coded
by the video encoder (503). In another example, the video source
(501) is a part of the electronic device (520).
[0061] The video source (501) may provide the source video sequence
to be coded by the video encoder (503) in the form of a digital
video sample stream that can be of any suitable bit depth (for
example: 8 bit, 10 bit, 12 bit, . . . ), any colorspace (for
example, BT.601 Y CrCB, RGB, . . . ), and any suitable sampling
structure (for example Y CrCb 4:2:0, Y CrCb 4:4:4). In a media
serving system, the video source (501) may be a storage device
storing previously prepared video. In a videoconferencing system,
the video source (501) may be a camera that captures local image
information as a video sequence. Video data may be provided as a
plurality of individual pictures that impart motion when viewed in
sequence. The pictures themselves may be organized as a spatial
array of pixels, wherein each pixel can comprise one or more
samples depending on the sampling structure, color space, etc. in
use. A person skilled in the art can readily understand the
relationship between pixels and samples. The description below
focuses on samples.
[0062] According to an embodiment, the video encoder (503) may code
and compress the pictures of the source video sequence into a coded
video sequence (543) in real time or under any other time
constraints as required by the application. Enforcing appropriate
coding speed is one function of a controller (550). In some
embodiments, the controller (550) controls other functional units
as described below and is functionally coupled to the other
functional units. The coupling is not depicted for clarity.
Parameters set by the controller (550) can include rate control
related parameters (picture skip, quantizer, lambda value of
rate-distortion optimization techniques, . . . ), picture size,
group of pictures (GOP) layout, maximum motion vector search range,
and so forth. The controller (550) can be configured to have other
suitable functions that pertain to the video encoder (503)
optimized for a certain system design.
[0063] In some embodiments, the video encoder (503) is configured
to operate in a coding loop. As an oversimplified description, in
an example, the coding loop can include a source coder (530) (e.g.,
responsible for creating symbols, such as a symbol stream, based on
an input picture to be coded, and a reference picture(s)), and a
(local) decoder (533) embedded in the video encoder (503). The
decoder (533) reconstructs the symbols to create the sample data in
a similar manner as a (remote) decoder also would create (as any
compression between symbols and coded video bitstream is lossless
in the video compression technologies considered in the disclosed
subject matter). The reconstructed sample stream (sample data) is
input to the reference picture memory (534). As the decoding of a
symbol stream leads to bit-exact results independent of decoder
location (local or remote), the content in the reference picture
memory (534) is also bit exact between the local encoder and remote
encoder. In other words, the prediction part of an encoder "sees"
as reference picture samples exactly the same sample values as a
decoder would "see" when using prediction during decoding. This
fundamental principle of reference picture synchronicity (and
resulting drift, if synchronicity cannot be maintained, for example
because of channel errors) is used in some related arts as
well.
[0064] The operation of the "local" decoder (533) can be the same
as of a "remote" decoder, such as the video decoder (410), which
has already been described in detail above in conjunction with FIG.
4. Briefly referring also to FIG. 4, however, as symbols are
available and encoding/decoding of symbols to a coded video
sequence by an entropy coder (545) and the parser (420) can be
lossless, the entropy decoding parts of the video decoder (410),
including the buffer memory (415), and parser (420) may not be
fully implemented in the local decoder (533).
[0065] An observation that can be made at this point is that any
decoder technology except the parsing/entropy decoding that is
present in a decoder also necessarily needs to be present, in
substantially identical functional form, in a corresponding
encoder. For this reason, the disclosed subject matter focuses on
decoder operation. The description of encoder technologies can be
abbreviated as they are the inverse of the comprehensively
described decoder technologies. Only in certain areas a more detail
description is required and provided below.
[0066] During operation, in some examples, the source coder (530)
may perform motion compensated predictive coding, which codes an
input picture predictively with reference to one or more
previously-coded picture from the video sequence that were
designated as "reference pictures". In this manner, the coding
engine (532) codes differences between pixel blocks of an input
picture and pixel blocks of reference picture(s) that may be
selected as prediction reference(s) to the input picture.
[0067] The local video decoder (533) may decode coded video data of
pictures that may be designated as reference pictures, based on
symbols created by the source coder (530). Operations of the coding
engine (532) may advantageously be lossy processes. When the coded
video data may be decoded at a video decoder (not shown in FIG. 5),
the reconstructed video sequence typically may be a replica of the
source video sequence with some errors. The local video decoder
(533) replicates decoding processes that may be performed by the
video decoder on reference pictures and may cause reconstructed
reference pictures to be stored in the reference picture cache
(534). In this manner, the video encoder (503) may store copies of
reconstructed reference pictures locally that have common content
as the reconstructed reference pictures that will be obtained by a
far-end video decoder (absent transmission errors).
[0068] The predictor (535) may perform prediction searches for the
coding engine (532). That is, for a new picture to be coded, the
predictor (535) may search the reference picture memory (534) for
sample data (as candidate reference pixel blocks) or certain
metadata such as reference picture motion vectors, block shapes,
and so on, that may serve as an appropriate prediction reference
for the new pictures. The predictor (535) may operate on a sample
block-by-pixel block basis to find appropriate prediction
references. In some cases, as determined by search results obtained
by the predictor (535), an input picture may have prediction
references drawn from multiple reference pictures stored in the
reference picture memory (534).
[0069] The controller (550) may manage coding operations of the
source coder (530), including, for example, setting of parameters
and subgroup parameters used for encoding the video data.
[0070] Output of all aforementioned functional units may be
subjected to entropy coding in the entropy coder (545). The entropy
coder (545) translates the symbols as generated by the various
functional units into a coded video sequence, by lossless
compressing the symbols according to technologies such as Huffman
coding, variable length coding, arithmetic coding, and so
forth.
[0071] The transmitter (540) may buffer the coded video sequence(s)
as created by the entropy coder (545) to prepare for transmission
via a communication channel (560), which may be a hardware/software
link to a storage device which would store the encoded video data.
The transmitter (540) may merge coded video data from the video
coder (503) with other data to be transmitted, for example, coded
audio data and/or ancillary data streams (sources not shown).
[0072] The controller (550) may manage operation of the video
encoder (503). During coding, the controller (550) may assign to
each coded picture a certain coded picture type, which may affect
the coding techniques that may be applied to the respective
picture. For example, pictures often may be assigned as one of the
following picture types:
[0073] An Intra Picture (I picture) may be one that may be coded
and decoded without using any other picture in the sequence as a
source of prediction. Some video codecs allow for different types
of intra pictures, including, for example Independent Decoder
Refresh ("IDR") Pictures. A person skilled in the art is aware of
those variants of I pictures and their respective applications and
features.
[0074] A predictive picture (P picture) may be one that may be
coded and decoded using intra prediction or inter prediction using
at most one motion vector and reference index to predict the sample
values of each block.
[0075] A bi-directionally predictive picture (B Picture) may be one
that may be coded and decoded using intra prediction or inter
prediction using at most two motion vectors and reference indices
to predict the sample values of each block. Similarly,
multiple-predictive pictures can use more than two reference
pictures and associated metadata for the reconstruction of a single
block.
[0076] Source pictures commonly may be subdivided spatially into a
plurality of sample blocks (for example, blocks of 4.times.4,
8.times.8, 4.times.8, or 16.times.16 samples each) and coded on a
block-by-block basis. Blocks may be coded predictively with
reference to other (already coded) blocks as determined by the
coding assignment applied to the blocks' respective pictures. For
example, blocks of I pictures may be coded non-predictively or they
may be coded predictively with reference to already coded blocks of
the same picture (spatial prediction or intra prediction). Pixel
blocks of P pictures may be coded predictively, via spatial
prediction or via temporal prediction with reference to one
previously coded reference picture. Blocks of B pictures may be
coded predictively, via spatial prediction or via temporal
prediction with reference to one or two previously coded reference
pictures.
[0077] The video encoder (503) may perform coding operations
according to a predetermined video coding technology or standard,
such as ITU-T Rec. H.265. In its operation, the video encoder (503)
may perform various compression operations, including predictive
coding operations that exploit temporal and spatial redundancies in
the input video sequence. The coded video data, therefore, may
conform to a syntax specified by the video coding technology or
standard being used.
[0078] In an embodiment, the transmitter (540) may transmit
additional data with the encoded video. The source coder (530) may
include such data as part of the coded video sequence. Additional
data may comprise temporal/spatial/SNR enhancement layers, other
forms of redundant data such as redundant pictures and slices, SEI
messages, VUI parameter set fragments, and so on.
[0079] A video may be captured as a plurality of source pictures
(video pictures) in a temporal sequence. Intra-picture prediction
(often abbreviated to intra prediction) makes use of spatial
correlation in a given picture, and inter-picture prediction makes
uses of the (temporal or other) correlation between the pictures.
In an example, a specific picture under encoding/decoding, which is
referred to as a current picture, is partitioned into blocks. When
a block in the current picture is similar to a reference block in a
previously coded and still buffered reference picture in the video,
the block in the current picture can be coded by a vector that is
referred to as a motion vector. The motion vector points to the
reference block in the reference picture, and can have a third
dimension identifying the reference picture, in case multiple
reference pictures are in use.
[0080] In some embodiments, a bi-prediction technique can be used
in the inter-picture prediction. According to the bi-prediction
technique, two reference pictures, such as a first reference
picture and a second reference picture that are both prior in
decoding order to the current picture in the video (but may be in
the past and future, respectively, in display order) are used. A
block in the current picture can be coded by a first motion vector
that points to a first reference block in the first reference
picture, and a second motion vector that points to a second
reference block in the second reference picture. The block can be
predicted by a combination of the first reference block and the
second reference block.
[0081] Further, a merge mode technique can be used in the
inter-picture prediction to improve coding efficiency.
[0082] According to some embodiments of the disclosure,
predictions, such as inter-picture predictions and intra-picture
predictions are performed in the unit of blocks. For example,
according to the HEVC standard, a picture in a sequence of video
pictures is partitioned into coding tree units (CTU) for
compression, the CTUs in a picture have the same size, such as
64.times.64 pixels, 32.times.32 pixels, or 16.times.16 pixels. In
general, a CTU includes three coding tree blocks (CTBs), which are
one luma CTB and two chroma CTBs. Each CTU can be recursively
quadtree split into one or multiple coding units (CUs). For
example, a CTU of 64.times.64 pixels can be split into one CU of
64.times.64 pixels, or 4 CUs of 32.times.32 pixels, or 16 CUs of
16.times.16 pixels. In an example, each CU is analyzed to determine
a prediction type for the CU, such as an inter prediction type or
an intra prediction type. The CU is split into one or more
prediction units (PUs) depending on the temporal and/or spatial
predictability. Generally, each PU includes a luma prediction block
(PB), and two chroma PBs. In an embodiment, a prediction operation
in coding (encoding/decoding) is performed in the unit of a
prediction block. Using a luma prediction block as an example of a
prediction block, the prediction block includes a matrix of values
(e.g., luma values) for pixels, such as 8.times.8 pixels,
16.times.16 pixels, 8.times.16 pixels, 16.times.8 pixels, and the
like.
[0083] FIG. 6 shows a diagram of a video encoder (603) according to
another embodiment of the disclosure. The video encoder (603) is
configured to receive a processing block (e.g., a prediction block)
of sample values within a current video picture in a sequence of
video pictures, and encode the processing block into a coded
picture that is part of a coded video sequence. In an example, the
video encoder (603) is used in the place of the video encoder (303)
in the FIG. 3 example.
[0084] In an HEVC example, the video encoder (603) receives a
matrix of sample values for a processing block, such as a
prediction block of 8.times.8 samples, and the like. The video
encoder (603) determines whether the processing block is best coded
using intra mode, inter mode, or bi-prediction mode using, for
example, rate-distortion optimization. When the processing block is
to be coded in intra mode, the video encoder (603) may use an intra
prediction technique to encode the processing block into the coded
picture; and when the processing block is to be coded in inter mode
or bi-prediction mode, the video encoder (603) may use an inter
prediction or bi-prediction technique, respectively, to encode the
processing block into the coded picture. In certain video coding
technologies, merge mode can be an inter picture prediction submode
where the motion vector is derived from one or more motion vector
predictors without the benefit of a coded motion vector component
outside the predictors. In certain other video coding technologies,
a motion vector component applicable to the subject block may be
present. In an example, the video encoder (603) includes other
components, such as a mode decision module (not shown) to determine
the mode of the processing blocks.
[0085] In the FIG. 6 example, the video encoder (603) includes the
inter encoder (630), an intra encoder (622), a residue calculator
(623), a switch (626), a residue encoder (624), a general
controller (621), and an entropy encoder (625) coupled together as
shown in FIG. 6.
[0086] The inter encoder (630) is configured to receive the samples
of the current block (e.g., a processing block), compare the block
to one or more reference blocks in reference pictures (e.g., blocks
in previous pictures and later pictures), generate inter prediction
information (e.g., description of redundant information according
to inter encoding technique, motion vectors, merge mode
information), and calculate inter prediction results (e.g.,
predicted block) based on the inter prediction information using
any suitable technique. In some examples, the reference pictures
are decoded reference pictures that are decoded based on the
encoded video information.
[0087] The intra encoder (622) is configured to receive the samples
of the current block (e.g., a processing block), in some cases
compare the block to blocks already coded in the same picture,
generate quantized coefficients after transform, and in some cases
also intra prediction information (e.g., an intra prediction
direction information according to one or more intra encoding
techniques). In an example, the intra encoder (622) also calculates
intra prediction results (e.g., predicted block) based on the intra
prediction information and reference blocks in the same
picture.
[0088] The general controller (621) is configured to determine
general control data and control other components of the video
encoder (603) based on the general control data. In an example, the
general controller (621) determines the mode of the block, and
provides a control signal to the switch (626) based on the mode.
For example, when the mode is the intra mode, the general
controller (621) controls the switch (626) to select the intra mode
result for use by the residue calculator (623), and controls the
entropy encoder (625) to select the intra prediction information
and include the intra prediction information in the bitstream; and
when the mode is the inter mode, the general controller (621)
controls the switch (626) to select the inter prediction result for
use by the residue calculator (623), and controls the entropy
encoder (625) to select the inter prediction information and
include the inter prediction information in the bitstream.
[0089] The residue calculator (623) is configured to calculate a
difference (residue data) between the received block and prediction
results selected from the intra encoder (622) or the inter encoder
(630). The residue encoder (624) is configured to operate based on
the residue data to encode the residue data to generate the
transform coefficients. In an example, the residue encoder (624) is
configured to convert the residue data from a spatial domain to a
frequency domain, and generate the transform coefficients. The
transform coefficients are then subject to quantization processing
to obtain quantized transform coefficients. In various embodiments,
the video encoder (603) also includes a residue decoder (628). The
residue decoder (628) is configured to perform inverse-transform,
and generate the decoded residue data. The decoded residue data can
be suitably used by the intra encoder (622) and the inter encoder
(630). For example, the inter encoder (630) can generate decoded
blocks based on the decoded residue data and inter prediction
information, and the intra encoder (622) can generate decoded
blocks based on the decoded residue data and the intra prediction
information. The decoded blocks are suitably processed to generate
decoded pictures and the decoded pictures can be buffered in a
memory circuit (not shown) and used as reference pictures in some
examples.
[0090] The entropy encoder (625) is configured to format the
bitstream to include the encoded block. The entropy encoder (625)
is configured to include various information according to a
suitable standard, such as the HEVC standard. In an example, the
entropy encoder (625) is configured to include the general control
data, the selected prediction information (e.g., intra prediction
information or inter prediction information), the residue
information, and other suitable information in the bitstream. Note
that, according to the disclosed subject matter, when coding a
block in the merge submode of either inter mode or bi-prediction
mode, there is no residue information.
[0091] FIG. 7 shows a diagram of a video decoder (710) according to
another embodiment of the disclosure. The video decoder (710) is
configured to receive coded pictures that are part of a coded video
sequence, and decode the coded pictures to generate reconstructed
pictures. In an example, the video decoder (710) is used in the
place of the video decoder (310) in the FIG. 3 example.
[0092] In the FIG. 7 example, the video decoder (710) includes an
entropy decoder (771), an inter decoder (780), a residue decoder
(773), a reconstruction module (774), and an intra decoder (772)
coupled together as shown in FIG. 7.
[0093] The entropy decoder (771) can be configured to reconstruct,
from the coded picture, certain symbols that represent the syntax
elements of which the coded picture is made up. Such symbols can
include, for example, the mode in which a block is coded (such as,
for example, intra mode, inter mode, bi-predicted mode, the latter
two in merge submode or another submode), prediction information
(such as, for example, intra prediction information or inter
prediction information) that can identify certain sample or
metadata that is used for prediction by the intra decoder (772) or
the inter decoder (780), respectively, residual information in the
form of, for example, quantized transform coefficients, and the
like. In an example, when the prediction mode is inter or
bi-predicted mode, the inter prediction information is provided to
the inter decoder (780); and when the prediction type is the intra
prediction type, the intra prediction information is provided to
the intra decoder (772). The residual information can be subject to
inverse quantization and is provided to the residue decoder
(773).
[0094] The inter decoder (780) is configured to receive the inter
prediction information, and generate inter prediction results based
on the inter prediction information.
[0095] The intra decoder (772) is configured to receive the intra
prediction information, and generate prediction results based on
the intra prediction information.
[0096] The residue decoder (773) is configured to perform inverse
quantization to extract de-quantized transform coefficients, and
process the de-quantized transform coefficients to convert the
residual from the frequency domain to the spatial domain. The
residue decoder (773) may also require certain control information
(to include the Quantizer Parameter (QP)), and that information may
be provided by the entropy decoder (771) (data path not depicted as
this may be low volume control information only).
[0097] The reconstruction module (774) is configured to combine, in
the spatial domain, the residual as output by the residue decoder
(773) and the prediction results (as output by the inter or intra
prediction modules as the case may be) to form a reconstructed
block, that may be part of the reconstructed picture, which in turn
may be part of the reconstructed video. It is noted that other
suitable operations, such as a deblocking operation and the like,
can be performed to improve the visual quality.
[0098] It is noted that the video encoders (303), (503), and (603),
and the video decoders (310), (410), and (710) can be implemented
using any suitable technique. In an embodiment, the video encoders
(303), (503), and (603), and the video decoders (310), (410), and
(710) can be implemented using one or more integrated circuits. In
another embodiment, the video encoders (303), (503), and (503), and
the video decoders (310), (410), and (710) can be implemented using
one or more processors that execute software instructions.
[0099] Aspects of the disclosure provide techniques for
constructing ranking-based spatial merge candidate list for
inter-picture prediction.
[0100] Generally, a motion vector for a block can be coded either
in an explicit way, to signal the difference to a motion vector
predictor (e.g., advanced motion vector prediction or AMVP mode);
or in an implicit way, to be indicated completely from one
previously coded or generated motion vector. The later one is
referred to as merge mode, meaning the current block is merged into
a previously coded block by using its motion information.
[0101] Both the AMVP mode and the merge mode construct candidate
list during decoding.
[0102] FIG. 8 shows an example of spatial and temporal candidates
in some examples.
[0103] For the merge mode in the inter prediction, merge candidates
in a candidate list are primarily formed by checking motion
information from either spatial or temporal neighboring blocks of
the current block. In the FIG. 8 example, candidate blocks A1, B1,
B0, A0 and B2 are sequentially checked. When any of the candidate
blocks are valid candidates, for example, are coded with motion
vectors, then, the motion information of the valid candidate blocks
can be added into the merge candidate list. Some pruning operation
is performed to make sure duplicated candidates will not be put
into the list again. The candidate blocks A1, B1, B0, A0 and B2 are
adjacent to corners of the current block, and are referred to as
corner candidates.
[0104] After spatial candidates, temporal candidates are also
checked into the list (merge candidate list). In some examples, the
current block's co-located block in a specified reference picture
is found. The motion information at C0 position (bottom right
corner of the current block) of the co-located block will be used
as temporal merge candidate. If the block at this position is not
coded in inter mode or not available, C1 position (at the outer
bottom right corner of the center of the co-located block) will be
used instead.
[0105] The advanced motion vector prediction (AMVP) mode in HEVC
refers to using spatial and temporal neighboring blocks' motion
information to predict the motion information of the current block,
while the prediction residue is further coded. Examples of spatial
and temporal neighboring candidates are shown in FIG. 8 as
well.
[0106] In some embodiments, in AMVP mode, a two-candidate motion
vector predictor list is formed. For example, the list includes a
first candidate predictor and a second candidate predictor. The
first candidate predictor is from the first available motion vector
from the left edge, in the order of spatial A0, A1 positions. The
second candidate predictor is from the first available motion
vector from the top edge, in the order of spatial B0, B1 and B2
positions. If no valid motion vector can be found from the checked
locations for either the left edge or the top edge, no candidate
will be filled in the list. If the two candidates available and are
the same, only one will be kept in the list. If the list is not
full (with two different candidates), the temporal co-located
motion vector (after scaling) from C0 location will be used as
another candidate. If motion information at C0 location is not
available, location C1 will be used instead.
[0107] In some examples, if there are still no enough motion vector
predictor candidates, zero motion vector will be used to fill up
the list.
[0108] In a related art, the order of candidates in the merge list
or in the AMVP predictor list is based on a pre-defined pattern,
for example, left candidate(s) (e.g., A0 and A1)->top
candidate(s) (e.g., B0, B1 and B2)->temporal candidate(s) (e.g.,
C0 and C1)-> . . . . However, the actual correlation between a
spatial/temporal neighbor and the current block may vary depending
on the content. The neighboring position with most similar motion
information as the current block may not always be the top
candidates in the merge list or in the AMVP predictor list.
[0109] Aspects of the disclosure provide techniques to further
improve MV predictor list in merge mode or AMVP mode. In some
embodiments, the MV candidate list is re-ordered according to the
correlations between neighboring blocks and the current block.
While the following description uses merge mode to illustrate the
techniques to re-order the MV candidate list, the techniques can be
similarly used in the AMVP mode as well.
[0110] Specifically, in some examples, the disclosed methods can
identify what are the merge candidate locations to be evaluated,
and determine statistics of the merge candidates at the merge
candidate locations. Further the disclosed methods can generate a
merge candidate list based on the ranking of the statistics of
evaluated merge candidates.
[0111] In an example, for large blocks or blocks with long sides,
more potential merge candidates are available along the long sides
of a block. Further, among all available spatial neighboring
blocks, multiple candidates can have the same motion information.
According to an aspect of the disclosure, the disclosed methods of
merge candidate derivation can include additional spatial
candidates (e.g., other than A0, A1, B0, B1 and B2) in the
candidate list, if the additional spatial candidates are available.
The candidate list can be conditionally constructed and pruned with
a ranking based method.
[0112] The disclosed method may extend the range of spatial
neighboring blocks to be considered as merge candidate. Various
techniques can be used to select potential merge candidates.
Additionally, the merge candidate list construction method can be
switched, based on certain conditions, between the original merge
candidate list construction method and the proposed ranking based
merge candidate list construction.
[0113] According to an aspect of the disclosure, additional spatial
merge candidates can be included in the merge candidate list. For
example, in addition to the spatial merge candidates A0-A1 and
B0-B2, new spatial merge candidates may be included into the merge
candidate list conditionally. In some examples, the merge candidate
list based on the spatial merge candidates A0-A1 and B0-B2 before
adding the spatial merge candidates is referred to as the original
merge candidate list.
[0114] In some embodiments, statistics of spatial merge candidates
at block edges are obtained. For example, before constructing the
merge candidate list, spatial neighboring blocks are scanned, and
the statistics of all or selected available spatial merge
candidates are collected. Then, a histogram of the motion
information is constructed, based on the count of neighboring
blocks with same motion information.
[0115] FIG. 9 shows a diagram of potential spatial merge candidates
of a current block (910) according to an embodiment of the
disclosure. In some examples, all spatial neighbors with minimum
block size (e.g., minimum motion-compensation block, such as
4.times.4 luma samples) which contain inter prediction information
adjacent to the left edge and top edge of current block are scanned
(e.g., checked for motion information). In the FIG. 9 example, a
first plurality of minimum size blocks (e.g., shown as L1, L2, L3,
. . . , Ln, . . . ) that are adjacent to left edge of the current
block (910) are scanned. Further, a second plurality of minimum
size blocks (e.g., shown as T1, T2, T3, . . . , Tm, . . . ) that
are adjacent to a top edge of the current block (910) are scanned.
In addition, the bottom-left neighboring block (e.g., shown as L0
in FIG. 9, which corresponds to A0 in FIG. 8), the above-right
neighboring block (e.g., shown as T0 in FIG. 9, which corresponds
to B0 in FIG. 8), and the above-left neighboring block (e.g., shown
as TL in FIG. 9, which corresponds to B2 in FIG. 8), are also
scanned. In the FIG. 9 example, the gray colored area (920)
includes all the spatial neighboring blocks with minimum block size
that are scanned, and the grey colored area (920) is referred to as
a scanning range (920) in some examples.
[0116] FIG. 10 shows a diagram of potential merge candidates of a
current block (1010) according to another embodiment of the
disclosure. In the FIG. 10 example, potential merge candidates can
be spatial candidates adjacent to the current block (1010) and can
be extended beyond bottom-left and above-right positions. The grey
colored area in FIG. 10 is the scanning range (1020) of the spatial
neighbors for the current block (1010) in some examples. The
scanning range (1020) of spatial neighbors includes all
minimum-sized (e.g., 4.times.4 luma samples) blocks which are
adjacent to the current block (1010), N minimum-sized blocks below
the bottom left neighboring block, and M minimum-sized blocks on
the right side of the above-right neighboring block. M and N are
positive integers, and can be the same integer or different
integers.
[0117] FIG. 11 shows a diagram of potential merge candidates of a
current block (1110) according to another embodiment of the
disclosure. In the FIG. 11 example, potential merge candidates
include multiple layers of spatial candidates. The grey colored
area in FIG. 11 is the scanning range (1120) of the spatial
neighboring blocks for the current block (1110) in some examples.
The scanning range (1120) of spatial neighboring blocks is extended
to a plurality layers, e.g., layer 1, layer 2 and layer 3, of
minimum-sized blocks. The order of layers is from the layer (e.g.,
layer 1) adjacent to the current block (1110), to the layer (e.g.,
layer 3) which is farthest away from the current block (1110). The
first layer (e.g., layer 1) includes all spatial neighboring blocks
with minimum block size which contain inter prediction information
adjacent to the left edge and top edge of current block. In
addition, the first layer (e.g., layer 1) includes the bottom-left
neighboring block, the above-right neighboring block, and the
above-left neighboring block. In each of the other layers, all
minimum-size blocks adjacent to the previous layer are included.
For example, the second layer (e.g., layer 2) includes all minimum
size blocks that are adjacent to the blocks in the first layer; and
the third layer (e.g., layer 3) includes all minimum size blocks
that are adjacent to the blocks in the second layer.
[0118] FIG. 12 shows a diagram of potential merge candidates of a
current block (1210) according to another embodiment of the
disclosure. In the FIG. 12 example, potential merge candidates
include multiple layers of spatial candidates. The grey colored
area in FIG. 12 is the scanning range (1220) of the spatial
neighboring blocks for the current block (1210) in some examples.
The scanning range (1220) of spatial neighboring blocks is extended
to a plurality layers, e.g., layer 1, layer 2 and layer 3, of
minimum-sized blocks. The order of layers is from the layer (e.g.,
layer 1) adjacent to the current block (1210), to the layer (e.g.,
layer 3) which is farthest away from the current block (1210). The
first layer (e.g., layer 1) includes all spatial neighboring blocks
with minimum block size which contain inter prediction information
adjacent to the left edge and top edge of current block. In
addition, the first layer (e.g., layer 1) includes the bottom-left
neighboring block and n more candidates below the bottom-left
neighboring block, the above-right neighboring block and M more
candidate on the right of the above-right neighboring block, and
the above-left neighboring block. In each of the other layers, all
minimum-size blocks adjacent to the previous layer are included.
For example, the second layer (e.g., layer 2) includes all minimum
size blocks that are adjacent to the blocks in the first layer; and
the third layer (e.g., layer 3) includes all minimum size blocks
that are adjacent to the blocks in the second layer.
[0119] FIG. 13 shows a diagram of potential merge candidates of a
current block (1310) according to another embodiment of the
disclosure. The scanning range (1320) is shown by the grey color
area. The scanning (also referred to as search) process is
performed according to a grid size (e.g., search grid height in the
vertical direction and search grid width in the horizontal
direction). The grid size is greater than or equal to minimum block
size. When the grid size equals to the minimum block size, the
scanning process is similar to the examples in FIG. 9 and FIG. 10
depending on whether the scanning range is extended. In some
examples, when the gird size is greater than the minimum block
size, for each grid unit, a representative block of the minimum
block size is selected for the grid unit as merge candidate.
[0120] FIG. 14 shows a diagram of potential merge candidates of a
current block (1410) according to another embodiment of the
disclosure. The scanning range (1420) is shown by the grey color
area. The scanning range (1420) includes multiple layers of spatial
neighboring blocks. The scanning (also referred to as search)
process is performed according to a grid size (e.g., search grid
height in the vertical direction and search grid width in the
horizontal direction). The grid size is greater than or equal to
minimum block size. When the grid size equals to the minimum block
size, the scanning process is similar to the examples in FIG. 11
and FIG. 12 depending on whether the scanning range is extended. In
some examples, when the gird size is greater than the minimum block
size, for each grid unit, a representative block of the minimum
block size is selected for the grid unit as merge candidate.
[0121] In some embodiments, when grid size is used and the width or
height of the grid size is larger than the minimum block size, the
merge candidate block with minimum block size may be located at a
certain location within the grid. In an embodiment, each
minimum-sized merge candidate block is located at the bottom right
corner of a grid unit, when the grid unit located on the left side
of the current block. In another embodiment, each minimum-size
merge candidate block is located at the top right corner of a grid
unit, when the grid unit is located on the left side of the current
block.
[0122] In an embodiment, each minimum-sized merge candidate block
is located at the bottom left corner of a grid unit, when the grid
unit is located on the above side of the current block. In another
embodiment, each minimum-size merge candidate block is located at
the bottom right corner of a grid unit, when the grid unit is
located on the above side of the current block.
[0123] In another embodiment, when the candidate block is located
on the left of current block and above the bottom-left neighboring
block (as A0 in FIG. 13), the minimum-size merge candidate block is
located at the bottom right corner of the grid unit. When candidate
block is in the same row with or below the bottom-left neighboring
block (as A0 depicted in FIG. 13), the minimum-size merge candidate
block is located at the top-right corner of the grid unit.
[0124] In another embodiment, when the candidate block is located
above of current block, when the candidate block is on the left of
the above-right neighboring block (depicted as B0 in FIG. 13), the
minimum-size merge candidate block is located at the bottom right
corner of the grid unit. When candidate block is in the same column
with or on the right of the above-right neighboring block (depicted
as B0 in FIG. 13), the minimum-size merge candidate block is
located at the bottom-left corner of the grid unit.
[0125] In another embodiment, when scanning the neighboring
minimum-sized blocks, when multiple minimum blocks belong to a same
neighboring (prediction) block (e.g. prediction unit) with the same
motion information, only one block is counted in the
statistics.
[0126] According to an aspect of the disclosure, the scanning range
of a current block is scanned to obtain motion information of the
neighboring blocks. After the scanning process, a histogram of
neighboring blocks' motion information is generated.
[0127] In an embodiment, the histogram is constructed with one
histogram interval (also known as bin) for each individual motion
information. Thus, the number of bins corresponds to the number of
individual motion vectors, in an example.
[0128] In another embodiment, the histogram is constructed with one
histogram interval (also known as bin) for a small range of motion
information. For example, when motion vector values of two
candidates are different by less than 1 pixel, the two candidates
can be considered the same and may be counted into one bin. It is
noted that the range of motion information in each bin is not
limited to the value used in this example. The motion information
range based binning process for constructing the histogram also
serves as a lossy pruning process.
[0129] When the motion information histogram is generated, a
sorting process is applied on the bins with non-zero counts. In an
embodiment, the motion information candidates are sorted in
descending order based on the count of each individual motion
information in the scanning range. In another embodiment, the
motion information candidates are sorted in ascending order based
on the count of each individual motion information.
[0130] According to an aspect of the disclosure, a merge candidate
list is constructed based on ranking of candidates according to the
histogram. In some embodiments, once the candidates are sorted, the
first N candidates (N is a positive integer and N<=maximum
number of merge candidates) may be added to the merge candidate
list in the sorted order.
[0131] In an embodiment, N is equal to the maximum number of merge
candidates. The generated merge candidate list is the final merge
candidate list.
[0132] In another embodiment, N is smaller than the maximum number
of merge candidates. Other suitable candidates can be added into
the remaining entries of the merge candidate list. For example, the
temporal merge candidate can be added into the merge candidate
list. In another example, artificial merge candidates, such as
combined bi-prediction merge candidates, or zero valued merge
candidates can be added into the merge candidate list.
[0133] In another embodiment, the first N candidates on the sorted
list may be inserted with other merge candidates, such as temporal
merge candidates, combined bi-prediction merge candidates, and zero
valued merge candidates, until the total number of candidates equal
to the maximum merge candidates.
[0134] According to an aspect of the disclosure, the ranking based
merge candidate list is constructed when certain conditions are
satisfied. When the certain conditions are not satisfied, the video
coding process can switch back to the original merge candidate
list. The switching based on the certain conditions between the
original merge candidate list and the ranking based merge candidate
list is referred to as conditional switching between the original
merge candidate list and the ranking based merge candidate
list.
[0135] The conditional switching is based on a size (e.g., a width
of the block, a height of the block) of the current block. In an
example, when the width and height of the current block are both
smaller than a threshold (e.g., 8 pixels), the original merge
candidate list (e.g., defined by HEVC standard) is constructed and
used. When the width or height of current block is larger than the
threshold (e.g., 8 pixels), the ranking based merge candidate list
is constructed and used in video encoding/decoding. It is noted
that the threshold is not limited to the value used in this
example. The threshold can be any width or height which is smaller
than the maximum block width or height.
[0136] In an embodiment, only the ranking based merge candidate is
constructed and used.
[0137] In another embodiment, the conditional switching is used to
determine whether certain conditions are satisfied in order to
construct the original merge candidate list or to construct the
ranking based merge candidate list.
[0138] FIG. 15 shows a flow chart outlining a process (1500)
according to an embodiment of the disclosure. The process (1500)
can be used in the reconstruction of a block coded in intra mode,
so to generate a prediction block for the block under
reconstruction. In various embodiments, the process (1500) are
executed by processing circuitry, such as the processing circuitry
in the terminal devices (210), (220), (230) and (240), the
processing circuitry that performs functions of the video encoder
(303), the processing circuitry that performs functions of the
video decoder (310), the processing circuitry that performs
functions of the video decoder (410), the processing circuitry that
performs functions of the intra prediction module (452), the
processing circuitry that performs functions of the video encoder
(503), the processing circuitry that performs functions of the
predictor (535), the processing circuitry that performs functions
of the intra encoder (622), the processing circuitry that performs
functions of the intra decoder (772), and the like. In some
embodiments, the process (1500) is implemented in software
instructions, thus when the processing circuitry executes the
software instructions, the processing circuitry performs the
process (1500). The process starts at (S1501) and proceeds to
(S1510).
[0139] At (S1510), prediction information of a block in a current
picture is decoded from a coded video bitstream. The prediction
information is indicative of an inter prediction mode, such as a
merge mode, a skip mode, and the like that determines a motion
vector for the block from a motion vector predictor.
[0140] At (S1520), a candidate list is constructed in response to
the inter prediction mode. The candidate list includes a plurality
of motion vector predictors arranged with a ranking order. The
motion vector predictors are sorted to have the ranking order based
on statistics of motion information in a spatial neighboring region
of the block, such as disclosed with reference to FIG. 9-FIG.
14.
[0141] At (S1530), a motion vector predictor is determined from the
candidate list according to the ranking order.
[0142] At (S1540), samples of the block are reconstructed according
to the motion vector predictor. Then, the process proceeds to
(S1599) and terminates.
[0143] The techniques described above, can be implemented as
computer software using computer-readable instructions and
physically stored in one or more computer-readable media. For
example, FIG. 16 shows a computer system (1600) suitable for
implementing certain embodiments of the disclosed subject
matter.
[0144] The computer software can be coded using any suitable
machine code or computer language, that may be subject to assembly,
compilation, linking, or like mechanisms to create code comprising
instructions that can be executed directly, or through
interpretation, micro-code execution, and the like, by one or more
computer central processing units (CPUs), Graphics Processing Units
(GPUs), and the like.
[0145] The instructions can be executed on various types of
computers or components thereof, including, for example, personal
computers, tablet computers, servers, smartphones, gaming devices,
internet of things devices, and the like.
[0146] The components shown in FIG. 16 for computer system (1600)
are exemplary in nature and are not intended to suggest any
limitation as to the scope of use or functionality of the computer
software implementing embodiments of the present disclosure.
Neither should the configuration of components be interpreted as
having any dependency or requirement relating to any one or
combination of components illustrated in the exemplary embodiment
of a computer system (1600).
[0147] Computer system (1600) may include certain human interface
input devices. Such a human interface input device may be
responsive to input by one or more human users through, for
example, tactile input (such as: keystrokes, swipes, data glove
movements), audio input (such as: voice, clapping), visual input
(such as: gestures), olfactory input (not depicted). The human
interface devices can also be used to capture certain media not
necessarily directly related to conscious input by a human, such as
audio (such as: speech, music, ambient sound), images (such as:
scanned images, photographic images obtain from a still image
camera), video (such as two-dimensional video, three-dimensional
video including stereoscopic video).
[0148] Input human interface devices may include one or more of
(only one of each depicted): keyboard (1601), mouse (1602),
trackpad (1603), touch screen (1610), data-glove (not shown),
joystick (1605), microphone (1606), scanner (1607), camera
(1608).
[0149] Computer system (1600) may also include certain human
interface output devices. Such human interface output devices may
be stimulating the senses of one or more human users through, for
example, tactile output, sound, light, and smell/taste. Such human
interface output devices may include tactile output devices (for
example tactile feedback by the touch-screen (1610), data-glove
(not shown), or joystick (1605), but there can also be tactile
feedback devices that do not serve as input devices), audio output
devices (such as: speakers (1609), headphones (not depicted)),
visual output devices (such as screens (1610) to include CRT
screens, LCD screens, plasma screens, OLED screens, each with or
without touch-screen input capability, each with or without tactile
feedback capability--some of which may be capable to output two
dimensional visual output or more than three dimensional output
through means such as stereographic output; virtual-reality glasses
(not depicted), holographic displays and smoke tanks (not
depicted)), and printers (not depicted).
[0150] Computer system (1600) can also include human accessible
storage devices and their associated media such as optical media
including CD/DVD ROM/RW (1620) with CD/DVD or the like media
(1621), thumb-drive (1622), removable hard drive or solid state
drive (1623), legacy magnetic media such as tape and floppy disc
(not depicted), specialized ROM/ASIC/PLD based devices such as
security dongles (not depicted), and the like.
[0151] Those skilled in the art should also understand that term
"computer readable media" as used in connection with the presently
disclosed subject matter does not encompass transmission media,
carrier waves, or other transitory signals.
[0152] Computer system (1600) can also include an interface to one
or more communication networks. Networks can for example be
wireless, wireline, optical. Networks can further be local,
wide-area, metropolitan, vehicular and industrial, real-time,
delay-tolerant, and so on. Examples of networks include local area
networks such as Ethernet, wireless LANs, cellular networks to
include GSM, 3G, 4G, 5G, LTE and the like, TV wireline or wireless
wide area digital networks to include cable TV, satellite TV, and
terrestrial broadcast TV, vehicular and industrial to include
CANBus, and so forth. Certain networks commonly require external
network interface adapters that attached to certain general purpose
data ports or peripheral buses (1649) (such as, for example USB
ports of the computer system (1600)); others are commonly
integrated into the core of the computer system (1600) by
attachment to a system bus as described below (for example Ethernet
interface into a PC computer system or cellular network interface
into a smartphone computer system). Using any of these networks,
computer system (1600) can communicate with other entities. Such
communication can be uni-directional, receive only (for example,
broadcast TV), uni-directional send-only (for example CANbus to
certain CANbus devices), or bi-directional, for example to other
computer systems using local or wide area digital networks. Certain
protocols and protocol stacks can be used on each of those networks
and network interfaces as described above.
[0153] Aforementioned human interface devices, human-accessible
storage devices, and network interfaces can be attached to a core
(1640) of the computer system (1600).
[0154] The core (1640) can include one or more Central Processing
Units (CPU) (1641), Graphics Processing Units (GPU) (1642),
specialized programmable processing units in the form of Field
Programmable Gate Areas (FPGA) (1643), hardware accelerators for
certain tasks (1644), and so forth. These devices, along with
Read-only memory (ROM) (1645), Random-access memory (1646),
internal mass storage such as internal non-user accessible hard
drives, SSDs, and the like (1647), may be connected through a
system bus (1648). In some computer systems, the system bus (1648)
can be accessible in the form of one or more physical plugs to
enable extensions by additional CPUs, GPU, and the like. The
peripheral devices can be attached either directly to the core's
system bus (1648), or through a peripheral bus (1649).
Architectures for a peripheral bus include PCI, USB, and the
like.
[0155] CPUs (1641), GPUs (1642), FPGAs (1643), and accelerators
(1644) can execute certain instructions that, in combination, can
make up the aforementioned computer code. That computer code can be
stored in ROM (1645) or RAM (1646). Transitional data can be also
be stored in RAM (1646), whereas permanent data can be stored for
example, in the internal mass storage (1647). Fast storage and
retrieve to any of the memory devices can be enabled through the
use of cache memory, that can be closely associated with one or
more CPU (1641), GPU (1642), mass storage (1647), ROM (1645), RAM
(1646), and the like.
[0156] The computer readable media can have computer code thereon
for performing various computer-implemented operations. The media
and computer code can be those specially designed and constructed
for the purposes of the present disclosure, or they can be of the
kind well known and available to those having skill in the computer
software arts.
[0157] As an example and not by way of limitation, the computer
system having architecture (1600), and specifically the core (1640)
can provide functionality as a result of processor(s) (including
CPUs, GPUs, FPGA, accelerators, and the like) executing software
embodied in one or more tangible, computer-readable media. Such
computer-readable media can be media associated with
user-accessible mass storage as introduced above, as well as
certain storage of the core (1640) that are of non-transitory
nature, such as core-internal mass storage (1647) or ROM (1645).
The software implementing various embodiments of the present
disclosure can be stored in such devices and executed by core
(1640). A computer-readable medium can include one or more memory
devices or chips, according to particular needs. The software can
cause the core (1640) and specifically the processors therein
(including CPU, GPU, FPGA, and the like) to execute particular
processes or particular parts of particular processes described
herein, including defining data structures stored in RAM (1646) and
modifying such data structures according to the processes defined
by the software. In addition or as an alternative, the computer
system can provide functionality as a result of logic hardwired or
otherwise embodied in a circuit (for example: accelerator (1644)),
which can operate in place of or together with software to execute
particular processes or particular parts of particular processes
described herein. Reference to software can encompass logic, and
vice versa, where appropriate. Reference to a computer-readable
media can encompass a circuit (such as an integrated circuit (IC))
storing software for execution, a circuit embodying logic for
execution, or both, where appropriate. The present disclosure
encompasses any suitable combination of hardware and software.
APPENDIX A: ACRONYMS
[0158] JEM: joint exploration model VVC: versatile video coding
BMS: benchmark set
MV: Motion Vector
HEVC: High Efficiency Video Coding
SEI: Supplementary Enhancement Information
VUI: Video Usability Information
GOPs: Groups of Pictures
TUs: Transform Units,
PUs: Prediction Units
CTUs: Coding Tree Units
CTBs: Coding Tree Blocks
PBs: Prediction Blocks
HRD: Hypothetical Reference Decoder
SNR: Signal Noise Ratio
CPUs: Central Processing Units
GPUs: Graphics Processing Units
CRT: Cathode Ray Tube
LCD: Liquid-Crystal Display
OLED: Organic Light-Emitting Diode
CD: Compact Disc
DVD: Digital Video Disc
ROM: Read-Only Memory
RAM: Random Access Memory
ASIC: Application-Specific Integrated Circuit
PLD: Programmable Logic Device
LAN: Local Area Network
[0159] GSM: Global System for Mobile communications
LTE: Long-Term Evolution
CANBus: Controller Area Network Bus
USB: Universal Serial Bus
PCI: Peripheral Component Interconnect
FPGA: Field Programmable Gate Areas
[0160] SSD: solid-state drive
IC: Integrated Circuit
CU: Coding Unit
[0161] While this disclosure has described several exemplary
embodiments, there are alterations, permutations, and various
substitute equivalents, which fall within the scope of the
disclosure. It will thus be appreciated that those skilled in the
art will be able to devise numerous systems and methods which,
although not explicitly shown or described herein, embody the
principles of the disclosure and are thus within the spirit and
scope thereof.
* * * * *