阅读说明：本技术 小型编码块的简化合并列表构建 (Reduced merge list construction for small code blocks ) 是由 许晓中 李翔 刘杉 于 2019-12-04 设计创作，主要内容包括：本公开的各方面提供了用于视频编码/解码的方法和装置。在一些示例中,用于视频解码的装置包括处理电路。该处理电路对当前图片中的当前块的预测信息进行解码。处理电路确定当前块的面积是否小于或等于阈值。处理电路构建包括多个运动矢量预测值的运动矢量预测值列表。运动矢量预测值的数目基于当前块的面积是否被确定为小于或等于阈值。处理电路基于运动矢量预测值列表来重建当前块。(Aspects of the present disclosure provide methods and apparatuses for video encoding/decoding. In some examples, an apparatus for video decoding includes a processing circuit. The processing circuit decodes prediction information for a current block in a current picture. The processing circuit determines whether the area of the current block is less than or equal to a threshold. The processing circuit constructs a motion vector predictor list comprising a plurality of motion vector predictors. The number of motion vector predictors is based on whether an area of the current block is determined to be less than or equal to a threshold value. The processing circuit reconstructs the current block based on the list of motion vector predictors.)

1. A method for video decoding in a decoder, comprising:

decoding prediction information for a current block in a current picture that is part of an encoded video sequence;

determining whether an area of the current block is less than or equal to a threshold;

constructing a motion vector predictor list including a plurality of motion vector predictors, a number of the motion vector predictors being based on whether an area of the current block is determined to be less than or equal to the threshold value; and

reconstructing the current block based on the list of motion vector predictors.

2. The method of claim 1, wherein,

when the area of the current block is determined to be less than or equal to the threshold value, the number of motion vector predictors included in the motion vector predictor list is a first number, and

the number of motion vector predictors included in the motion vector predictor list is a second number greater than the first number when the area of the current block is determined to be greater than the threshold.

3. The method of claim 2, wherein when the prediction information indicates a partition size of the current block, the constructing further comprises:

construct the motion vector predictor list based on whether the partition size is determined to be less than or equal to the threshold, wherein,

when the partition size is determined to be less than or equal to the threshold value, the number of motion vector predictors included in the motion vector predictor list is a first number, and

the number of motion vector predictors included in the motion vector predictor list is a second number when the partition size is determined to be greater than the threshold.

4. The method of claim 1, wherein the threshold is a preset number of luma samples.

5. The method of claim 1, wherein the threshold corresponds to a picture resolution of the current picture.

6. The method of claim 1, wherein the threshold is signaled in the encoded video sequence.

7. The method of claim 2, wherein the motion vector predictor list comprising the first number of motion vector predictors is constructed based on a first set of spatial or temporal motion vector predictors smaller than a second set of spatial or temporal motion vector predictors used to construct the motion vector predictor list comprising the second number of motion vector predictors.

8. The method of claim 2, wherein the motion vector predictor list comprising the first number of motion vector predictors does not comprise any spatial or temporal motion vector predictor.

9. The method of claim 2, wherein a first number of redundancy checks is performed to construct a motion vector predictor list including the first number of motion vector predictors and a second number of redundancy checks is performed to construct a motion vector predictor list including the second number of motion vector predictors, the first number of redundancy checks being less than the second number of redundancy checks.

10. The method of claim 9, wherein the first number of redundancy checks does not include at least one of: (i) a comparison between a possible spatial motion vector predictor and a first existing spatial motion vector predictor in the motion vector predictor list, (ii) a comparison between a possible temporal motion vector predictor and a first existing temporal motion vector predictor in the motion vector predictor list, (iii) a comparison between a possible history-based motion vector predictor and a first existing spatial motion vector predictor or another existing spatial motion vector predictor in the motion vector predictor list, and (iv) a comparison between the possible history-based motion vector predictor and a first existing temporal motion vector predictor or another existing temporal motion vector predictor in the motion vector predictor list.

11. The method of claim 2, wherein a motion vector predictor list comprising the first number of motion vector predictors is constructed without performing any redundancy check.

12. The method of claim 1, wherein at least one of the motion vector predictors uses the current picture as a reference picture.

13. An apparatus for video decoding, comprising a processing circuit configured to:

decoding prediction information for a current block in a current picture that is part of an encoded video sequence;

determining whether an area of the current block is less than or equal to a threshold;

constructing a motion vector predictor list including a plurality of motion vector predictors, a number of the motion vector predictors being based on whether an area of the current block is determined to be less than or equal to the threshold value; and

reconstructing the current block based on the list of motion vector predictors.

14. The apparatus of claim 13, wherein

When the area of the current block is determined to be less than or equal to the threshold value, the number of motion vector predictors included in the motion vector predictor list is a first number, and

the number of motion vector predictors included in the motion vector predictor list is a second number greater than the first number when the area of the current block is determined to be greater than the threshold.

15. The apparatus of claim 14, wherein the processing circuit is further configured to:

construct the motion vector predictor list based on whether the partition size is determined to be less than or equal to the threshold value, when the prediction information indicates the partition size of the current block, wherein,

when the partition size is determined to be less than or equal to the threshold value, the number of motion vector predictors included in the motion vector predictor list is a first number, and

the number of motion vector predictors included in the motion vector predictor list is a second number when the partition size is determined to be greater than the threshold.

16. The apparatus of claim 13, wherein the threshold is a preset number of luma samples.

17. The apparatus of claim 13, wherein the threshold is a preset number of luma samples.

18. The apparatus of claim 13, wherein the threshold is signaled in the encoded video sequence.

19. The apparatus of claim 14, wherein the motion vector predictor list comprising the first number of motion vector predictors is constructed based on a first set of spatial or temporal motion vector predictors smaller than a second set of spatial or temporal motion vector predictors used to construct the motion vector predictor list comprising the second number of motion vector predictors.

20. A non-transitory computer-readable storage medium storing a program executable by at least one processor to perform operations comprising:

decoding prediction information for a current block in a current picture that is part of an encoded video sequence;

determining whether an area of the current block is less than or equal to a threshold;

constructing a motion vector predictor list including a plurality of motion vector predictors, a number of the motion vector predictors being based on whether an area of the current block is determined to be less than or equal to the threshold value; and

reconstructing the current block based on the list of motion vector predictors.

Technical Field

This application describes embodiments generally related to video coding.

Background

The description in this background section is intended to present the background of the disclosure in general. Work of the presently named inventors, to the extent it 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 or impliedly admitted as prior art against the present disclosure.

Video encoding and decoding may be performed using inter-prediction with motion compensation. Uncompressed digital video may include a series of pictures, each picture having, for example, 1920 x 1080 luma samples and associated chroma samples in a spatial dimension. A series of pictures may have a fixed or variable picture rate (also informally referred to as frame rate), e.g. 60 pictures per second or 60 Hz. Uncompressed video has high bitrate requirements. For example, 1080p 604 with 8 bits per sample: 2:0 video (1920 × 1080 luminance sample resolution at 60Hz frame rate) requires a bandwidth of approximately 1.5 Gbit/s. An hour of the above video requires more than 600GB of storage space.

One purpose of video encoding and decoding may be to reduce redundancy of an input video signal by compression. Compression may help reduce the bandwidth requirements or storage space requirements described above, in some cases by two or more orders of magnitude. Lossless compression, lossy compression, and a combination of the two may be employed. Lossless compression refers to a technique by which an exact copy of an original signal can be reconstructed from a compressed original signal. When lossy compression is used, the reconstructed signal may be different from the original signal, but the distortion between the original signal and the reconstructed signal is small enough that the reconstructed signal is usable for the target application. Lossy compression is widely used in video. 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 that can be achieved may reflect: higher allowable/tolerable distortion can result in higher compression ratios.

Video encoders and decoders may utilize techniques in several broad categories including, for example, motion compensation, transform, quantization, and entropy coding.

Video codec techniques may include a technique referred to as intra-coding. In intra coding, sample values are represented without reference to samples or other data from previously reconstructed reference pictures. In some video codecs, a picture is spatially subdivided into blocks of samples. When all sample blocks are encoded in intra mode, the picture may be an intra picture. Intra pictures and their derivatives (e.g., independent decoder refresh pictures) can be used to reset decoder states and thus can be used as the first picture in an encoded video bitstream and video session or as still images. Samples of an intra block may be subjected to a transform and the transform coefficients may be quantized prior to entropy encoding. Intra prediction may be a technique that minimizes sample values in the pre-transform domain. In some cases, the smaller the DC value after transformation, and the smaller the AC coefficient, the fewer bits are needed to represent the block after entropy coding at a given quantization step.

Conventional intra-frame coding, such as known from, for example, MPEG-2 generation coding techniques, does not use intra-frame prediction. However, some newer video compression techniques include techniques that attempt to utilize, for example, metadata and/or surrounding sample data obtained during encoding/decoding of data blocks that are spatially adjacent and preceding in decoding order. Such techniques are hereinafter referred to as "intra-prediction" techniques. Note that in at least some cases, intra prediction only uses reference data from the current picture in reconstruction, and does not use reference data from the reference picture.

There may be many different forms of intra prediction. When more than one such technique may be used in a given video coding technique, the technique used may be coded in intra-prediction mode. In some cases, a mode may have sub-modes and/or parameters, and these sub-modes and/or parameters may be encoded separately or included in a mode codeword. Which codeword is used for a given mode/sub-mode/parameter combination may have an impact on the coding efficiency gain through intra-prediction and, therefore, on the entropy coding technique used to convert the codeword into a bitstream.

Some modes of intra prediction are introduced by h.264, refined in h.265, and further refined in newer coding techniques such as joint development model (JEM), universal video coding (VVC), and reference set (BMS). Neighboring sample values belonging to already available samples may be used to form a block of prediction values. Sample values of neighboring samples are copied into the prediction block according to the direction. The reference to the direction used may be encoded in the bitstream or may itself be predicted.

Referring to fig. 1A, a subset of 9 predictor directions known from the 33 possible predictor directions of h.265 (33 angular modes corresponding to 35 intra modes) is depicted at the bottom right. The point (101) where the arrows converge represents the predicted sample. The arrows indicate the direction in which the samples are predicted. For example, arrow (102) indicates that the sample (101) is predicted from one or more samples at an angle of 45 degrees to the horizontal from the top right. Similarly, arrow (103) indicates that the sample (101) is predicted from one or more samples at an angle of 22.5 degrees to the horizontal below and to the left of the sample (101).

Still referring to fig. 1, a square block (104) of 4 x 4 samples is depicted at the top left (indicated by the bold dashed line). Block 104 includes 16 samples. Each sample is labeled "S", its position in the Y dimension (e.g., row index), and its position in the X dimension (e.g., column index). For example, sample S21 is the second sample in the Y dimension (from the top) and the first sample in the X dimension (from the left). Similarly, sample S44 is the fourth sample in block (104) in both the Y dimension and the X dimension. Since the block size is 4 × 4 samples, S44 is in the lower right. Further shown are reference samples, which follow a similar numbering scheme. The reference sample is labeled by R, its Y position (e.g., row index) and X position (column index) relative to block (104). In both h.264 and h.265, the prediction samples are adjacent to the block in reconstruction; and therefore negative values need not be used.

Intra picture prediction may work by copying reference sample values from neighboring samples occupied by the prediction direction represented by the signal. For example, assume that the encoded video bitstream includes signaling indicating, for the block, a prediction direction that coincides with the arrow (102) -i.e., samples are predicted from one or more predicted samples at an angle of 45 degrees from horizontal, at the top right. In this case, the samples S41, S32, S23, and S14 are predicted from the same reference sample R05. The sample was then predicted from the reference sample R08S 44.

In some cases, the values of multiple reference samples may be combined, for example by interpolation, to compute a reference sample; especially when the direction is not evenly divisible by 45 degrees.

As video coding techniques have evolved, the number of possible directions has also increased. In h.264 (2003), nine different directions can be represented. This increased to 33 in h.265 (2013) and JEM/VVC/BMS could support up to 65 directions at the time of publication. Experiments have been performed to identify the most likely directions, and some techniques in entropy coding are used to represent those possible directions with a small number of bits, accepting some penalty for less likely directions. Further, sometimes the direction itself may be predicted from the neighboring direction used in neighboring decoded blocks.

Fig. 1B shows a diagram of 65 intra prediction directions according to JEM to show the number of prediction directions increasing with time (105).

The mapping of intra prediction direction bits representing directions in the encoded video bitstream may vary from video encoding technique to video encoding technique; and for example a simple direct mapping from prediction direction to intra prediction mode to codeword to a complex adaptation scheme involving the most probable mode and similar techniques. In all cases, however, there will be certain directions that are statistically less likely to occur in the video content than certain other directions. Since the goal of video compression is to reduce redundancy, in well-working video coding techniques, those less likely directions will be represented by a larger number of bits than more likely directions.

Motion compensation may be a lossy compression technique and may involve the following techniques: after spatial movement in the direction indicated by a motion vector (hereinafter MV), a block of sample data from a previously reconstructed picture or part thereof, i.e. using a reference picture, is used to predict a newly reconstructed picture or part thereof. In some cases, the reference picture may be the same as the current reconstructed picture. The MV may have two dimensions, X and Y, or may have three dimensions, where the third dimension indicates the reference picture in use (the latter dimension may be indirectly the temporal dimension).

In some video compression techniques, an MV that is available for a certain region of sample data may be predicted based on other MVs, e.g., a MV that is related to another region of sample data that is spatially adjacent to the region being reconstructed and that is earlier in decoding order. This can greatly reduce the amount of data required to encode the MV, thereby eliminating redundancy and improving compression rate. For example, MV prediction can function effectively because when encoding an input video signal (referred to as natural video) derived from an image pickup device, there is a statistical possibility that a region larger than a region to which a single MV is applied moves in a similar direction, so that a similar motion vector can be derived from MVs of adjacent regions to predict the single MV in some cases. The above makes the MV sought for a given region similar or identical to the MVs predicted from the surrounding MVs, so that after entropy coding it is possible to represent the MV using fewer bits than if the MV were coded directly. In some cases, MV prediction may be an example of lossless compression of a signal (i.e., MV) derived from an original signal (i.e., a sample stream). In other cases, MV prediction itself may be lossy, for example due to rounding errors when calculating the predicted value based on several surrounding MVs.

Various MV prediction mechanisms are described in H.265/HEVC (ITU-T H.265 recommendation, "High Efficiency Video Coding", 2016 (12 months) to Hi-Fi). Among the many MV prediction mechanisms provided by h.265, Advanced Motion Vector Prediction (AMVP) mode and merge mode are described herein.

In AMVP mode, motion information of spatial and temporal neighboring blocks of a current block may be used to predict motion information of the current block while further encoding a prediction residual. Examples of spatial and temporal neighbor candidates are shown in fig. 1C and 1D, respectively. A list of dual candidate motion vector predictors is formed. As shown in FIG. 1C, the first candidate predictor is from the first available motion vectors of two blocks A0(112), A1(113) at the lower left corner of the current block (111). The second candidate predictor is from the first available motion vectors of the three blocks B0(114), B1(115), and B2(116) above the current block (111). If no valid motion vector can be found from the checked position, no candidates will be filled in the list. If two available candidates have the same motion information, only one candidate will remain in the list. If the list is not full, i.e. the list does not have two different candidates, the temporally co-located motion vector (scaled) from C0(122) at the lower right corner of the co-located block (121) in the reference picture will be used as another candidate, as shown in fig. 1D. If motion information at the C0(122) position is not available, the center position of the co-located block in the reference picture, C1(123), will be used instead. In the above derivation, if there are still not enough motion vector predictor candidates, the list will be populated with zero motion vectors. Two flags mvp _ L0_ flag and mvp _ L1_ flag are signaled in the bitstream to indicate the AMVP index (0 or 1) of MV candidate lists L0 and L1, respectively.

In merge mode for inter-picture prediction, if a merge flag (including a skip flag) is signaled as TRUE (TRUE), a merge index is signaled to indicate which candidate in the merge candidate list is to be used to indicate the motion vector of the current block. At the decoder, a merge candidate list is constructed based on the spatial and temporal neighbors of the current block. As shown in fig. 1C, a maximum of four MVs derived from five spatial neighboring blocks (a0 through B2) are added to the merge candidate list. In addition, as shown in fig. 1D, at most one MV from two temporally co-located blocks (C0 and C1) in the reference picture is added to the list. The additional merge candidates include a combined bi-directional prediction candidate and a zero motion vector candidate. Before taking the motion information of the block as a merge candidate, a redundancy check is performed to check whether the block is identical to an element in the current merge candidate list. If the block is not the same as each element in the current merge candidate list, the block is added as a merge candidate to the merge candidate list. Maxmargecandnum is defined as the size of the merge candidate list in terms of the number of candidates. In HEVC, maxmergencardnum is signaled in the bitstream. The skip mode can be considered as a special merge mode with zero residual.

In VVC, similar to Temporal Motion Vector Prediction (TMVP) in HEVC, a sub-block based temporal motion vector prediction (SbTMVP) method may use the motion field in co-located pictures to improve motion vector prediction and merging modes for CUs in the current picture. The same co-located picture used by TMVP is used for SbTVMP. SbTMVP differs from TMVP in two main respects: (1) TMVP predicts motion at CU level, but SbTMVP predicts motion at sub-CU level; (2) although TMVP derives a temporal motion vector from a co-located block in the co-located picture (the co-located block is the bottom-right or center block relative to the current CU), SbTMVP applies a motion shift derived from a motion vector of one of the spatial neighboring blocks of the current CU prior to deriving temporal motion information from the co-located picture.

SbTVMP processing is shown in fig. 1E and 1F. SbTMVP predicts the motion vectors of sub-CUs within the current CU in two steps. In a first step, as shown in FIG. 1E, the spatial neighbors of the current block (131) are checked in the order A1(132), B1(133), B0(134) and A0 (135). Once the first available spatial neighboring block is identified with a motion vector that uses the co-located picture as its reference picture, the motion vector is selected as the motion shift to be applied. If no such motion vector is identified from the spatial neighbors, the motion shift is set to (0, 0).

In a second step, the motion shift identified in the first step is applied (i.e., added to the coordinates of the current block) to obtain sub-CU level motion information (e.g., motion vectors and reference indices) from the co-located picture as shown in fig. 1F. The example in fig. 1F assumes that the motion shift (149) is set to the motion vector (143) of the spatially neighboring block a 1. Then, for a current sub-CU (e.g., sub-CU (144)) in a current block (142) of the current picture (141), motion information of a corresponding co-located sub-CU (e.g., co-located sub-CU (154)) in a co-located block (152) of a co-located picture (151) is used to derive motion information of the current sub-CU. In a similar manner to TMVP processing in HEVC, motion information of a corresponding co-located sub-CU (e.g., co-located sub-CU (154)) is converted to a motion vector and reference index of a current sub-CU (e.g., sub-CU (144)), where temporal motion scaling is applied to align a reference picture of the temporal motion vector with a reference picture of the current CU.

In VVC, a merge sub-block-based merge list containing both SbTVMP candidates and affine merge candidates may be used in the sub-block-based merge mode. The SbTVMP mode is enabled/disabled by a Sequence Parameter Set (SPS) flag. If SbTMVP mode is enabled, the SbTMVP predictor is added as the first entry of the sub-block based merge list, followed by the affine merge candidate. In some applications, the maximum allowed size of the sub-block based merge list is 5. For example, the sub-CU size used in SbTMVP is fixed to 8 × 8. As with the affine merge mode, the SbTMVP mode is applicable only to CUs having a width and height greater than or equal to 8.

The coding logic of the additional SbTMVP merge candidates is the same as the coding logic of the other merge candidates. That is, for each CU in a P or B slice, an additional rate-distortion (RD) check is performed to determine whether to use SbTMVP candidates.

In VVC, a history-based mvp (HMVP) method includes HMVP candidates defined as motion information of previously encoded blocks. A table with multiple HMVP candidates is maintained during the encoding/decoding process. When a new slice is encountered, the table is emptied. Whenever there is an inter-coded non-affine block, the associated motion information is added as a new HMVP candidate to the last entry of the table. The encoding flow of the HMVP method is shown in fig. 1G.

The table size S is set to 6, which indicates that a maximum of 6 HMVP candidates can be added to the table. When a new motion candidate is inserted into the table, the constrained FIFO rule is utilized such that a redundancy check is first applied to determine if the same HMVP is present in the table. If found, the same HMVP is removed from the table and all HMVP candidates are moved forward, i.e., the index is decreased by 1. Fig. 1H shows an example of inserting a new motion candidate into the HMVP table.

The HMVP candidates may be used in the merge candidate list construction process. The latest HMVP candidates in the table are checked in order and inserted into the candidate list after the TMVP candidate. Pruning is applied to the HMVP candidates to exclude spatial or temporal merge candidates other than subblock motion candidates (i.e., ATMVP).

To reduce the number of pruning operations, the number of HMVP candidates to be checked (denoted by L) is set to L ═ (N < ═ 4)? M (8-N), where N indicates the number of non-sub-block merge candidates available and M indicates the number of HMVP candidates available in the table. In addition, the merge candidate list construction process from the HMVP list is terminated once the total number of available merge candidates reaches the signaled maximum allowed merge candidate minus 1. Furthermore, the logarithm used for combining bi-predictive merging candidate derivations is reduced from 12 to 6.

The HMVP candidates may also be used in the AMVP candidate list construction process. The motion vectors of the last K HMVP candidates in the table are inserted after the TMVP candidate. Only HMVP candidates having the same reference picture as the AMVP target reference picture are used to construct the AMVP candidate list. Pruning is applied to the HMVP candidates. In some applications, K is set to 4 while the AMVP list size remains unchanged, i.e., equal to 2.

Pairwise average candidates are generated by averaging predefined candidate pairs in the current merge candidate list. In VVC, the number of pairwise average candidates is 6, and the predefined pairs are defined as { (0,1), (0,2), (1,2), (0,3), (1,3), (2,3) }, where a number represents a merge index of the merge candidate list. The average motion vector is calculated separately for each reference list. If both motion vectors are available in one list, they are averaged even if they point to different reference pictures. If only one motion vector is available, one motion vector is used directly. If no motion vector is available, the list is considered invalid. The pairwise average candidate may replace a combined candidate in the HEVC standard.

Multi-hypothesis prediction may be applied to improve the single prediction of AMVP mode. A flag is signaled to enable or disable multi-hypothesis prediction. In addition, when the flag is true, an additional merge index is signaled. In this way, multi-hypothesis prediction converts uni-prediction to bi-prediction, where one prediction is obtained using the original syntax elements in AMVP mode and the other prediction is obtained using merge mode. As with bi-directional prediction, the final prediction combines the two predictions together using 1:1 weights. A merge candidate list is first derived from the merge mode excluding sub-CU candidates (e.g., affine, Alternative Temporal Motion Vector Prediction (ATMVP)). Next, the merge candidate list is split into two separate lists, one for list 0(L0) containing all L0 motions from the candidates, and the other for list 1(L1) containing all L1 motions. After removing redundancy and filling in the gaps, two merge lists are generated for L0 and L1, respectively. When applying multi-hypothesis prediction to improve AMVP mode, there are two constraints. First, this function is enabled for those CUs with luma Coded Block (CB) area greater than or equal to 64. Second, for low-delay B pictures, only L1 applies.

Disclosure of Invention

Aspects disclosed herein provide methods and apparatuses for video encoding/decoding. In some examples, an apparatus for video decoding includes a receive circuit and a processing circuit.

The processing circuit decodes prediction information for a current block in a current picture that is part of an encoded video sequence. The processing circuit determines whether the area of the current block is less than or equal to a threshold. The processing circuit constructs a motion vector predictor list comprising a plurality of motion vector predictors. The number of motion vector predictors is based on whether an area of the current block is determined to be less than or equal to a threshold value. The processing circuit reconstructs the current block based on the list of motion vector predictors.

According to aspects of the present disclosure, the number of motion vector predictors included in the motion vector predictor list is a first number when the area of the current block is determined to be less than or equal to a threshold value, and the number of motion vector predictors included in the motion vector predictor list is a second number greater than the first number when the area of the current block is determined to be greater than the threshold value.

According to aspects of the present disclosure, the prediction information indicates that the current block is to be further divided into a plurality of smaller blocks. The processing circuit divides a current block into a plurality of smaller blocks. The processing circuit determines whether an area of one of the plurality of smaller blocks is less than or equal to a threshold. The processing circuit constructs a motion vector predictor list based on whether an area of one of the plurality of smaller blocks is determined to be less than or equal to a threshold. The number of motion vector predictors included in the motion vector predictor list is a first number when an area of one of the plurality of smaller blocks is determined to be less than or equal to a threshold, and the number of motion vector predictors included in the motion vector predictor list is a second number when the area of one of the plurality of smaller blocks is determined to be greater than the threshold.

According to aspects of the present disclosure, the prediction information indicates a partition size of the current block. The processing circuit determines whether the partition size is less than or equal to a threshold. The processing circuit constructs a motion vector predictor list based on whether the partition size is determined to be less than or equal to a threshold. The number of motion vector predictors included in the motion vector predictor list is a first number when the partition size is determined to be less than or equal to the threshold value, and the number of motion vector predictors included in the motion vector predictor list is a second number when the partition size is determined to be greater than the threshold value.

In an embodiment, the threshold is a preset number of luminance samples.

In an embodiment, the threshold corresponds to a picture resolution of the current picture.

In an embodiment, the threshold is signaled in the encoded video sequence.

In an embodiment, a motion vector predictor list comprising a first number of motion vector predictors is constructed based on a first set of spatial or temporal motion vector predictors. The first set of spatial or temporal motion vector predictors is smaller than a second set of spatial or temporal motion vector predictors used for constructing a motion vector predictor list comprising a second number of motion vector predictors.

In an embodiment, the motion vector predictor list comprising the first number of motion vector predictors does not comprise any spatial or temporal motion vector predictor.

In an embodiment, a first number of redundancy checks is performed to construct a motion vector predictor list comprising the first number of motion vector predictors, and a second number of redundancy checks is performed to construct a motion vector predictor list comprising the second number of motion vector predictors. The first number of redundancy checks is less than the second number of redundancy checks.

In an embodiment, the first number of redundancy checks does not include at least one of: (i) a comparison between a possible spatial motion vector predictor and a first existing spatial motion vector predictor in a list of motion vector predictors, (ii) a comparison between a possible temporal motion vector predictor and a first existing temporal motion vector predictor in a list of motion vector predictors, (iii) a comparison between a possible history-based motion vector predictor and a first existing spatial motion vector predictor or another existing spatial motion vector predictor in a list of motion vector predictors, and (iv) a comparison between a possible history-based motion vector predictor and a first existing temporal motion vector predictor or another existing temporal motion vector predictor in a list of motion vector predictors.

In an embodiment, a motion vector predictor list comprising a first number of motion vector predictors is constructed without performing any redundancy check.

In an embodiment, at least one of the motion vector predictors uses the current picture as a reference picture, such that a reference block of the at least one of the motion vector predictors is within the current picture.

Aspects of the present disclosure also provide a non-transitory computer-readable medium storing instructions that, when executed by a computer for video decoding, cause the computer to perform any one or combination of methods for video decoding.

Drawings

Further features, properties, and various advantages of the disclosed subject matter will become more apparent from the following detailed description and the accompanying drawings, in which:

fig. 1A is a schematic diagram of an exemplary subset of intra prediction modes.

Fig. 1B is a diagram of exemplary intra prediction directions.

Fig. 1C is a schematic diagram of a current block and its surrounding spatial merge candidates in an example.

Fig. 1D is a schematic diagram of co-located block and temporal merging candidates in one example.

Fig. 1E is a diagram of a current block and its surrounding spatial merge candidates for sub-block based temporal motion vector prediction (SbTMVP), according to an example.

Fig. 1F is an exemplary process of deriving SbTMVP candidates according to one example.

Fig. 1G is a decoding flow of a history-based motion vector prediction (HMVP) method in one example.

Fig. 1H is an exemplary process of updating a table in an HMVP according to one example.

Fig. 2 is a schematic diagram of a simplified block diagram of a communication system according to an embodiment.

Fig. 3 is a schematic illustration of a simplified block diagram of a communication system according to an embodiment.

FIG. 4 is a simplified block diagram of a decoder in one embodiment;

FIG. 5 is a schematic diagram of a simplified block diagram of an encoder in one embodiment;

FIG. 6 shows a block diagram of another encoder in another embodiment;

FIG. 7 shows a block diagram of another decoder in another embodiment;

fig. 8 shows a flowchart outlining an exemplary process according to some embodiments of the present disclosure.

Fig. 9 shows another flowchart outlining an exemplary process according to some embodiments of the present disclosure.

FIG. 10 is a schematic diagram of a computer system according to an embodiment of the present application.

Detailed Description

Fig. 2 is a simplified block diagram of a communication system (200) according to an embodiment disclosed herein. The communication system (200) includes a plurality of terminal devices that can communicate with each other through, for example, a network (250). For example, a communication system (200) includes a first terminal device (210) and a second terminal device (220) interconnected by a network (250). In the embodiment of fig. 2, the first terminal device (210) and the second terminal device (220) perform unidirectional data transmission. For example, a first terminal device (210) may encode video data, such as a stream of video pictures captured by the terminal device (210), for transmission over a network (250) to another second terminal device (220). The encoded video data may be transmitted in the form of one or more encoded video streams. The second terminal device (220) may receive the encoded video data from the network (250), decode the encoded video data to recover the video data, and display a video picture according to the recovered video data. Unidirectional data transmission is common in applications such as media services.

In another embodiment, a communication system (200) includes a third terminal device (230) and a fourth terminal device (240) that perform bidirectional transmission of encoded video data, which may occur, for example, during a video conference. For bi-directional data transmission, each of the third terminal device (230) and the fourth terminal device (240) may encode video data (e.g., a stream of video pictures captured by the terminal device) for transmission over the network (250) to the other of the third terminal device (230) and the fourth terminal device (240). Each of the third terminal device (230) and the fourth terminal device (240) may also receive encoded video data transmitted by the other of the third terminal device (230) and the fourth terminal device (240), and may decode the encoded video data to recover the video data, and may display video pictures on an accessible display device according to the recovered video data.

In the embodiment of fig. 2, the first terminal device (210), the second terminal device (220), the third terminal device (230), and the fourth terminal device (240) may be a server, a personal computer, and a smart phone, but the principles disclosed herein may not be limited thereto. Embodiments disclosed herein may be used with laptop computers, tablet computers, media players, and/or dedicated video conferencing devices. Network (250) represents any number of networks that communicate encoded video data between first terminal device (210), second terminal device (220), third terminal device (230), and fourth terminal device (240), including, for example, wired (wired) and/or wireless communication networks. The communication network (250) may exchange data in circuit-switched and/or packet-switched channels. The network may include a telecommunications network, a local area network, a wide area network, and/or the internet. For purposes of the present discussion, the architecture and topology of the network (250) may be immaterial to the operation disclosed herein, unless explained below.

By way of example, fig. 3 illustrates the placement of a video encoder and a video decoder in a streaming environment. The subject matter disclosed herein is equally applicable to other video-enabled applications including, for example, video conferencing, digital TV, storing compressed video on digital media including CDs, DVDs, memory sticks, and the like.

The streaming system may include an acquisition subsystem (313), which may include a video source (301), such as a digital camera, that creates an uncompressed video picture stream (302). In an embodiment, the video picture stream (302) includes samples taken by a digital camera. The video picture stream (302) is depicted as a thick line to emphasize a high data amount video picture stream compared to the encoded video data (304) (or encoded video code stream), the video picture stream (302) being processable by an electronic device (320), the electronic device (320) comprising a video encoder (303) coupled to a video source (301). The video encoder (303) may comprise hardware, software, or a combination of hardware and software to implement or embody aspects of the disclosed subject matter as described in more detail below. The encoded video data (304) (or encoded video codestream (304)) is depicted as a thin line to emphasize the lower data amount of the encoded video data (304) (or encoded video codestream (304)) as compared to the video picture stream (302), which may be stored on a streaming server (305) for future use. One or more streaming client subsystems, such as client subsystem (306) and client subsystem (308) in fig. 3, may access streaming server (305) to retrieve copies (307) and copies (309) of encoded video data (304). The client subsystem (306) may include, for example, a video decoder (310) in an electronic device (330). The video decoder (310) decodes incoming copies (307) of the encoded video data and generates an output video picture stream (311) that may be presented on a display (312), such as a display screen, or another presentation device (not shown). In some streaming systems, encoded video data (304), video data (307), and video data (309) (e.g., video streams) may be encoded according to certain video encoding/compression standards. Examples of such standards include ITU-T H.265. In an embodiment, the video coding standard under development is informally referred to as VVC, and the present application may be used in the context of the VVC standard.

It should be noted that electronic device (320) and electronic device (330) may include other components (not shown). For example, the electronic device (320) may include a video decoder (not shown), and the electronic device (330) may also include a video encoder (not shown).

Fig. 4 is a block diagram of a video decoder (410) according to an embodiment of the present disclosure. The video decoder (410) may be disposed in an electronic device (430). The electronic device (430) may include a receiver (431) (e.g., a receive circuit). The video decoder (410) may be used in place of the video decoder (310) in the fig. 3 embodiment.

The receiver (431) may receive one or more encoded video sequences to be decoded by the video decoder (410); in the same or another embodiment, the encoded video sequences are received one at a time, wherein each encoded video sequence is decoded independently of the other encoded video sequences. The encoded video sequence may be received from a channel (401), which may be a hardware/software link to a storage device that stores encoded video data. The receiver (431) may receive encoded video data as well as other data, e.g., encoded audio data and/or auxiliary data streams, which may be forwarded to their respective usage entities (not labeled). The receiver (431) may separate the encoded video sequence from other data. To prevent network jitter, a buffer memory (415) may be coupled between the receiver (431) and the entropy decoder/parser (420) (hereinafter "parser (420)"). In some applications, the buffer memory (415) is part of the video decoder (410). In other applications, the buffer memory (415) may be external (not depicted) to the video decoder (410). While in other cases a buffer memory (not labeled) is provided external to the video decoder (410), e.g., to prevent network jitter, and another buffer memory (415) may be configured internal to the video decoder (410), e.g., to handle playout timing. The buffer memory (415) may not be required to be configured or may be made smaller when the receiver (431) receives data from a store/forward device with sufficient bandwidth and controllability or from an isochronous network. Of course, for use over traffic packet networks such as the internet, a buffer memory (415) may also be required, which may be relatively large and may be of an adaptive size, and may be implemented at least partially in an operating system or similar element (not labeled) external to the video decoder (410).

The video decoder (410) may include a parser (420) to reconstruct symbols (421) from the encoded video sequence. The categories of these symbols include information for managing the operation of the video decoder (410), as well as potential information to control a display device, such as a display screen (412), that is not an integral part of the electronic device (430), but may be coupled to the electronic device (430), as shown in fig. 4. The control Information for the display device may be a parameter set fragment (not shown) of Supplemental Enhancement Information (SEI message) or Video Usability Information (VUI). The parser (420) may parse/entropy decode the received encoded video sequence. Encoding of the encoded video sequence may be performed in accordance with video coding techniques or standards and may follow various principles, including variable length coding, Huffman coding, arithmetic coding with or without contextual sensitivity, and so forth. A parser (420) may extract a subgroup parameter set for at least one of the subgroups of pixels in the video decoder from the encoded video sequence based on at least one parameter corresponding to the group. A subgroup may include a Group of Pictures (GOP), a picture, a tile, a slice, a macroblock, a Coding Unit (CU), a block, a Transform Unit (TU), a Prediction Unit (PU), and so on. The parser (420) may also extract information from the encoded video sequence, such as transform coefficients, quantizer parameter values, motion vectors, and so on.

The parser (420) may perform entropy decoding/parsing operations on the video sequence received from the buffer memory (415), thereby creating symbols (421).

The reconstruction of the symbol (421) may involve a number of different units depending on the type of the encoded video picture or portion of the encoded video picture (e.g., inter and intra pictures, inter and intra blocks), among other factors. Which units are involved and the way in which they are involved can be controlled by subgroup control information parsed from the coded video sequence by a parser (420). For the sake of brevity, such a subgroup control information flow between parser (420) and a plurality of units below is not described.

In addition to the functional blocks already mentioned, the video decoder (410) may be conceptually subdivided into several functional units as described below. In a practical embodiment operating under business constraints, many of these units interact closely with each other and may be integrated with each other. However, for the purposes of describing the disclosed subject matter, a conceptual subdivision into the following functional units is appropriate.

The first unit is a scaler/inverse transform unit 451. The sealer/inverse transform unit (451) receives the quantized transform coefficients as symbol(s) (421) from the parser (420) along with control information, including which transform mode to use, block size, quantization factor, quantization scaling matrix, etc. The sealer/inverse transform unit (451) may output a block comprising sample values, which may be input into the aggregator (455).

In some cases, the output samples of sealer/inverse transform unit (451) may belong to an intra-coded block; namely: predictive information from previously reconstructed pictures is not used, but blocks of predictive information from previously reconstructed portions of the current picture may be used. Such predictive information may be provided by intra picture prediction unit (452). In some cases, the intra picture prediction unit (452) generates a surrounding block of the same size and shape as the block being reconstructed using the reconstructed information extracted from the current picture buffer (458). For example, the current picture buffer (458) buffers a partially reconstructed current picture and/or a fully reconstructed current picture. In some cases, the aggregator (455) adds, on a per-sample basis, the prediction information generated by the intra prediction unit (452) to the output sample information provided by the scaler/inverse transform unit (451).

In other cases, the output samples of sealer/inverse transform unit (451) may belong to inter-coded and potential motion compensated blocks. In this case, motion compensated prediction unit (453) may access reference picture memory (457) to extract samples for prediction. After motion compensating the extracted samples according to the sign (421), the samples may be added to the output of the scaler/inverse transform unit (451), in this case referred to as residual samples or residual signals, by an aggregator (455), thereby generating output sample information. The fetching of prediction samples by motion compensated prediction unit (453) from addresses within reference picture memory (457) may be controlled by motion vectors, and the motion vectors are used by motion compensated prediction unit (453) in the form of the symbol (421), e.g., comprising X, Y and a reference picture component. Motion compensation may also include interpolation of sample values fetched from the reference picture memory (457), motion vector prediction mechanisms, etc., when using sub-sample exact motion vectors.

The output samples of the aggregator (455) may be employed in a loop filter unit (456) by various loop filtering techniques. The video compression techniques may include in-loop filter techniques that are controlled by parameters included in the encoded video sequence (also referred to as an encoded video bitstream) and that are available to the loop filter unit (456) as symbols (421) from the parser (420), however, in other embodiments, the video compression techniques may also be responsive to meta-information obtained during decoding of previous (in decoding order) portions of the encoded picture or encoded video sequence, as well as to sample values previously reconstructed and loop filtered.

The output of the loop filter unit (456) may be a stream of samples that may be output to a display device (412) and stored in a reference picture memory (457) for subsequent inter picture prediction.

Once fully reconstructed, some of the coded pictures may be used as reference pictures for future prediction. For example, once the encoded picture corresponding to the current picture is fully reconstructed and the encoded picture is identified (by, e.g., parser (420)) as a reference picture, current picture buffer (458) may become part of reference picture memory (457) and a new current picture buffer may be reallocated before reconstruction of a subsequent encoded picture begins.

The video decoder (410) may perform decoding operations according to predetermined video compression techniques, such as in the ITU-T rec.h.265 standard. The encoded video sequence may conform to the syntax specified by the video compression technique or standard used, in the sense that the encoded video sequence conforms to the syntax of the video compression technique or standard and the configuration files recorded in the video compression technique or standard. In particular, the configuration file may select certain tools from all tools available in the video compression technology or standard as the only tools available under the configuration file. For compliance, the complexity of the encoded video sequence is also required to be within the limits defined by the level of the video compression technique or standard. In some cases, the hierarchy limits the maximum picture size, the maximum frame rate, the maximum reconstruction sampling rate (measured in units of, e.g., mega samples per second), the maximum reference picture size, and so on. In some cases, the limits set by the hierarchy may be further defined by a Hypothetical Reference Decoder (HRD) specification and metadata signaled HRD buffer management in the encoded video sequence.

In an embodiment, receiver (431) may receive additional (redundant) data along with the encoded video. The additional data may be part of an encoded video sequence. The additional data may be used by the video decoder (410) to properly decode the data and/or more accurately reconstruct the original video data. The additional data may be in the form of, for example, a temporal, spatial, or signal-to-noise ratio (SNR) enhancement layer, a redundant slice, a redundant picture, a forward error correction code, and so forth.

Fig. 5 is a block diagram of a video encoder (503) according to an embodiment of the present disclosure. The video encoder (503) is disposed in the electronic device (520). The electronic device (520) includes a transmitter (540) (e.g., a transmission circuit). The video encoder (503) may be used in place of the video encoder (303) in the fig. 3 embodiment.

Video encoder (503) may receive video samples from a video source (501) (not part of electronics (520) in the fig. 5 embodiment) that may capture video images to be encoded by video encoder (503). In another embodiment, the video source (501) is part of the electronic device (520).

The video source (501) may provide a source video sequence in the form of a digital video sample stream to be encoded by the video encoder (503), which may have any suitable bit depth (e.g., 8 bits, 10 bits, 12 bits, etc.), any color space (e.g., bt.601y CrCB, RGB, etc.), and any suitable sampling structure (e.g., Y CrCB 4:2:0, Y CrCB 4:4: 4). In the media service system, the video source (501) may be a storage device that stores previously prepared video. In a video conferencing system, the video source 501 may be a camera device that captures local image information as a video sequence. Video data may be provided as a plurality of individual pictures that are given motion when viewed in sequence. The picture itself may be constructed as an array of spatial pixels, where each pixel may comprise one or more samples, depending on the sampling structure, color space, etc. used. The relationship between pixels and samples can be readily understood by those skilled in the art. The following text focuses on describing the samples.

According to an embodiment, the video encoder (503) may encode and compress pictures of a source video sequence into an encoded video sequence (543) in real-time or under any other temporal constraints required by the application. It is a function of the controller (550) to perform the appropriate encoding speed. In some embodiments, the controller (550) controls and is functionally coupled to other functional units as described below. For simplicity, the couplings are not labeled in the figures. The parameters set by the controller (550) may include rate control related parameters (picture skip, quantizer, lambda value of rate distortion optimization technique, etc.), picture size, group of pictures (GOP) layout, maximum motion vector search range, etc. The controller (550) may be used to have other suitable functions relating to the video encoder (503) optimized for a certain system design.

In some embodiments, the video encoder (503) operates in an encoding loop. As a brief description, in an embodiment, an encoding loop may include a source encoder (530) (e.g., responsible for creating symbols, such as a symbol stream, based on input pictures and reference pictures to be encoded) and a (local) decoder (533) embedded in the video encoder (503). The decoder (533) reconstructs the symbols to create sample data in a similar manner as the (remote) decoder creates the sample data (since any compression between the symbols and the encoded video stream is lossless in the video compression techniques considered in this application). The reconstructed sample stream (sample data) is input to a reference picture memory (534). Since the decoding of the symbol stream produces bit accurate results independent of decoder location (local or remote), the content in the reference picture store (534) also corresponds bit-accurately between the local encoder and the remote encoder. In other words, the reference picture samples that the prediction portion of the encoder "sees" are identical to the sample values that the decoder would "see" when using prediction during decoding. This reference picture synchronization philosophy (and the drift that occurs if synchronization cannot be maintained due to, for example, channel errors) is also used in some related techniques.

The operation of "local" decoder (533) may be the same as a "remote" decoder, such as video decoder (410) that has been described in detail above in connection with fig. 4. However, referring briefly to fig. 4 additionally, when symbols are available and the entropy encoder (545) and parser (420) are able to losslessly encode/decode the symbols into an encoded video sequence, the entropy decoding portion of the video decoder (410), including the buffer memory (415) and parser (420), may not be fully implemented in the decoder (533).

At this point it can be observed that any decoder technique other than the parsing/entropy decoding present in the decoder must also be present in the corresponding encoder in substantially the same functional form. For this reason, the present application focuses on decoder operation. The description of the encoder techniques may be simplified because the encoder techniques are reciprocal to the fully described decoder techniques. A more detailed description is only needed in certain areas and is provided below.

During operation, in some embodiments, the source encoder (530) may perform motion compensated predictive encoding that predictively encodes an input picture, referencing one or more previously encoded pictures from the video sequence that are designated as "reference pictures". In this way, an encoding engine (532) encodes differences between pixel blocks of an input picture and pixel blocks of a reference picture, which may be selected as a prediction reference for the input picture.

The decoder (533) may decode encoded video data that may be designated as a picture of a reference picture based on the symbols created by the source encoder (530). The operation of the encoding engine (532) may be a lossy process. When the encoded video data can be decoded at a video decoder (not shown in fig. 5), the reconstructed video sequence may typically be a copy of the source video sequence with some errors. The decoder (533) replicates a decoding process, which may be performed on reference pictures by a video decoder, and may cause reconstructed reference pictures to be stored in the reference picture memory (534). In this way, the video encoder (503) may locally store a copy of the reconstructed reference picture that has common content (no transmission errors) with the reconstructed reference picture to be obtained by the remote video decoder.

The predictor (535) may perform a prediction search against the coding engine (532). That is, for a new picture to be encoded, predictor (535) may search reference picture memory (534) for sample data (as candidate reference pixel blocks) or some metadata, such as reference picture motion vectors, block shapes, etc., that may be referenced as appropriate predictions for the new picture. The predictor (535) may operate on a block-by-block basis of samples to find a suitable prediction reference. In some cases, from search results obtained by predictor (535), it may be determined that the input picture may have prediction references taken from multiple reference pictures stored in reference picture memory (534).

The controller (550) may manage encoding operations of the source encoder (530), including, for example, setting parameters and subgroup parameters for encoding video data.

The outputs of all of the above functional units may be entropy encoded in an entropy encoder (545). The entropy encoder (545) losslessly compresses the symbols generated by the various functional units according to techniques such as huffman coding, variable length coding, arithmetic coding, etc., to convert the symbols into an encoded video sequence.

The transmitter (540) may buffer the encoded video sequence created by the entropy encoder (545) in preparation for transmission over a communication channel (560), which may be a hardware/software link to a storage device that will store the encoded video data. The transmitter (540) may combine the encoded video data from the video encoder (503) with other data to be transmitted, such as encoded audio data and/or an auxiliary data stream (sources not shown).

The controller (550) may manage the operation of the video encoder (503). During encoding, the controller (550) may assign a certain encoded picture type to each encoded picture, but this may affect the encoding techniques applicable to the respective picture. For example, pictures may be generally assigned to any of the following picture types:

intra pictures (I pictures), which may be pictures that can be encoded and decoded without using any other picture in the sequence as a prediction source. Some video codecs tolerate different types of intra pictures, including, for example, Independent Decoder Refresh ("IDR") pictures. Those skilled in the art are aware of variants of picture I and their corresponding applications and features.

Predictive pictures (P pictures), which may be pictures that may be encoded and decoded using intra prediction or inter prediction that uses at most one motion vector and reference index to predict sample values of each block.

Bi-predictive pictures (B-pictures), which may be pictures that can be encoded and decoded using intra-prediction or inter-prediction that uses at most two motion vectors and reference indices to predict sample values of each block. Similarly, multiple predictive pictures may use more than two reference pictures and associated metadata for reconstructing a single block.

A source picture may typically be spatially subdivided into blocks of samples (e.g., blocks of 4 x 4, 8 x 8, 4 x 8, or 16 x 16 samples) and encoded block-wise. These blocks may be predictively encoded with reference to other (encoded) blocks that are determined according to the encoding allocation applied to their respective pictures. For example, a block of an I picture may be non-predictive encoded, or the block may be predictive encoded (spatial prediction or intra prediction) with reference to an already encoded block of the same picture. The pixel block of the P picture can be prediction-coded by spatial prediction or by temporal prediction with reference to one previously coded reference picture. A block of a B picture may be prediction coded by spatial prediction or by temporal prediction with reference to one or two previously coded reference pictures.

The video encoder (503) may perform encoding operations according to a predetermined video encoding technique or standard, such as the ITU-T rec.h.265 recommendation. In its operation, the video encoder (403) may perform various compression operations, including predictive encoding operations that exploit temporal and spatial redundancies in the input video sequence. Thus, the encoded video data may conform to syntax specified by the video coding technique or standard used.

In an embodiment, the transmitter (540) may transmit the additional data and the encoded video when transmitting the encoded video. The source encoder (530) may treat such data as part of a video sequence that may be encoded. The additional data may include temporal/spatial/SNR enhancement layers, redundant pictures and slices, among other forms of redundant data, SEI messages, VUI parameter set segments, and the like.

The captured video may be provided as a plurality of source pictures (video pictures) in a time sequence. Intra-picture prediction, often abbreviated as intra-prediction, exploits spatial correlation in a given picture, while inter-picture prediction exploits (temporal or other) correlation between pictures. In an embodiment, the particular picture being encoded/decoded, referred to as the current picture, is partitioned into blocks. When a block in a current picture is similar to a reference block in a reference picture that has been previously encoded in video and is still buffered, the block in the current picture may be encoded by a vector called a motion vector. The motion vector points to a reference block in a reference picture, and in the case where multiple reference pictures are used, the motion vector may have a third dimension that identifies the reference picture.

In some embodiments, bi-directional prediction techniques may be used in inter-picture prediction. According to bi-prediction techniques, two reference pictures are used, e.g., a first reference picture and a second reference picture that are both prior to the current picture in video in decoding order (but may be past and future, respectively, in display order). A block in a current picture may be encoded by a first motion vector pointing to a first reference block in a first reference picture and a second motion vector pointing to a second reference block in a second reference picture. In particular, the block may be predicted by a combination of a first reference block and a second reference block.

Furthermore, merge mode techniques may be used in inter picture prediction to improve coding efficiency.

According to some embodiments disclosed herein, prediction such as inter-picture prediction and intra-picture prediction is performed in units of blocks. For example, according to the HEVC standard, pictures in a sequence of video pictures are divided into Coding Tree Units (CTUs) for compression, the CTUs in the pictures having the same size, such as 64 × 64 pixels, 32 × 32 pixels, or 16 × 16 pixels. In general, a CTU includes three Coding Tree Blocks (CTBs), which are one luminance CTB and two chrominance CTBs. Further, each CTU may be further split into one or more Coding Units (CUs) in a quadtree. For example, a 64 × 64-pixel CTU may be split into one 64 × 64-pixel CU, or 4 32 × 32-pixel CUs, or 16 × 16-pixel CUs. In an embodiment, each CU is analyzed to determine a prediction type for the CU, such as an inter prediction type or an intra prediction type. Furthermore, depending on temporal and/or spatial predictability, a CU is split into one or more Prediction Units (PUs). In general, each PU includes a luma Prediction Block (PB) and two chroma blocks PB. In an embodiment, a prediction operation in encoding (encoding/decoding) is performed in units of prediction blocks. Taking a luma prediction block as an example of a prediction block, the prediction block includes a matrix of pixel values (e.g., luma values), such as 8 × 8 pixels, 16 × 16 pixels, 8 × 16 pixels, 16 × 8 pixels, and so on.

Fig. 6 is a diagram of a video encoder (603) according to another embodiment of the present disclosure. A video encoder (603) is used 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 an encoded picture that is part of an encoded video sequence. In this embodiment, a video encoder (603) is used in place of the video encoder (303) in the embodiment of fig. 3.

In an HEVC embodiment, a video encoder (603) receives a matrix of sample values for a processing block, e.g., a prediction block of 8 × 8 samples, etc. The video encoder (603) uses, for example, rate-distortion (RD) optimization to determine whether to encode the processing block using intra mode, inter mode, or bi-directional prediction mode. When encoding a processing block in intra mode, the video encoder (603) may use intra prediction techniques to encode the processing block into an encoded picture; and when the processing block is encoded in inter mode or bi-prediction mode, the video encoder (603) may encode the processing block into the encoded picture using inter prediction or bi-prediction techniques, respectively. In some video coding techniques, the merge mode may be an inter-picture prediction sub-mode, in which motion vectors are derived from one or more motion vector predictors without resorting to coded motion vector components outside of the predictors. In some other video coding techniques, there may be motion vector components that are applicable to the subject block. In an embodiment, the video encoder (603) comprises other components, such as a mode decision module (not shown) for determining a processing block mode.

In the embodiment of fig. 6, the video encoder (603) comprises an inter encoder (630), an intra encoder (622), a residual calculator (623), a switch (626), a residual encoder (624), a general controller (621), and an entropy encoder (625) coupled together as shown in fig. 6.

The inter encoder (630) is used to receive samples of a current block (e.g., a processing block), compare the block to one or more reference blocks in a reference picture (e.g., blocks in previous and subsequent pictures), generate inter prediction information (e.g., redundant information descriptions, motion vectors, merge mode information according to inter coding techniques), and calculate inter prediction results (e.g., predicted blocks) using any suitable technique based on the inter prediction information. In some embodiments, the reference picture is a decoded reference picture that is decoded based on encoded video information.

An intra encoder (622) is used to receive samples of a current block (e.g., a processing block), in some cases compare the block to a block already encoded in the same picture, generate quantized coefficients after transformation, and in some cases also generate intra prediction information (e.g., intra prediction direction information according to one or more intra coding techniques). In an embodiment, the intra encoder (622) also computes intra prediction results (e.g., predicted blocks) based on the intra prediction information and reference blocks in the same picture.

The universal controller (621) is used to determine universal control data and control other components of the video encoder (603) based on the universal control data. In an embodiment, a general purpose controller (621) determines a mode of a block and provides a control signal to a switch (626) based on the mode. For example, when the mode is intra, the general purpose controller (621) controls the switch (626) to select an intra mode result for use by the residual calculator (623), and controls the entropy encoder (625) to select intra prediction information and add the intra prediction information in the code stream; and when the mode is an inter mode, the general purpose controller (621) controls the switch (626) to select an inter prediction result for use by the residual calculator (623), and controls the entropy encoder (625) to select and add inter prediction information in the code stream.

A residual calculator (623) is used to calculate the difference (residual data) between the received block and the prediction result selected from the intra encoder (622) or the inter encoder (630). A residual encoder (624) is operative based on the residual data to encode the residual data to generate transform coefficients. In an embodiment, a residual encoder (624) is used to convert residual data from the time domain to the frequency domain and generate transform coefficients. The transform coefficients are then subjected to a quantization process to obtain quantized transform coefficients. In various embodiments, the video encoder (603) also includes a residual decoder (628). A residual decoder (628) is used to perform the inverse transform and generate decoded residual data. The decoded residual data may be suitably used by an intra encoder (622) and an inter encoder (630). For example, inter encoder (630) may generate a decoded block based on decoded residual data and inter prediction information, and intra encoder (622) may generate a decoded block based on decoded residual data and intra prediction information. The decoded blocks are processed appropriately to generate a decoded picture, and in some embodiments, the decoded picture may be buffered in a memory circuit (not shown) and used as a reference picture.

An entropy coder (625) is used to format the code stream to produce coded blocks. The entropy encoder (625) generates various information according to a suitable standard such as the HEVC standard. In an embodiment, the entropy encoder (625) is used to obtain general control data, selected prediction information (e.g., intra prediction information or inter prediction information), residual information, and other suitable information in the code stream. Note that, according to the disclosed subject matter, there is no residual information when a block is encoded in a merge sub-mode of an inter mode or a bi-prediction mode.

Fig. 7 is a diagram of a video decoder (710) according to another embodiment of the present disclosure. A video decoder (710) is for receiving an encoded image that is part of an encoded video sequence and decoding the encoded image to generate a reconstructed picture. In an embodiment, the video decoder (710) is used in place of the video decoder (310) in the fig. 3 embodiment.

In the fig. 7 embodiment, video decoder (710) includes an entropy decoder (771), an inter-frame decoder (780), a residual decoder (773), a reconstruction module (774), and an intra-frame decoder (772) coupled together as shown in fig. 7.

An entropy decoder (771) may be used to reconstruct certain symbols from an encoded picture, which represent syntax elements that constitute the encoded picture. Such symbols may include, for example, a mode used to encode the block (e.g., intra mode, inter mode, bi-prediction mode, a merge sub-mode of the latter two, or another sub-mode), prediction information (e.g., intra prediction information or inter prediction information) that may identify certain samples or metadata for use by an intra decoder 772 or an inter decoder 780, respectively, residual information in the form of, for example, quantized transform coefficients, and so forth. In an embodiment, when the prediction mode is inter or bi-directional prediction mode, inter prediction information is provided to an inter decoder (780); and providing the intra prediction information to an intra decoder (772) when the prediction type is an intra prediction type. The residual information may be inverse quantized and provided to a residual decoder (773).

An inter-frame decoder (780) is configured to receive inter-frame prediction information and generate an inter-frame prediction result based on the inter-frame prediction information.

An intra decoder (772) is used for receiving intra prediction information and generating a prediction result based on the intra prediction information.

A residual decoder (773) is used to perform inverse quantization to extract dequantized transform coefficients and process the dequantized transform coefficients to convert the residual from the frequency domain to the spatial domain. The residual decoder (773) may also need some control information (to obtain the quantizer parameter QP) and that information may be provided by the entropy decoder (771) (data path not labeled as this is only low-level control information).

A reconstruction module (774) is used to combine the residuals output by the residual decoder (773) and the prediction results (which may be output by an inter prediction module or an intra prediction module) in the spatial domain to form a reconstructed block, which may be part of a reconstructed picture, which in turn may be part of a reconstructed video. It should be noted that other suitable operations, such as deblocking operations, may be performed to improve visual quality.

It should be noted that video encoder (303), video encoder (503), and video encoder (603) as well as video decoder (310), video decoder (410), and video decoder (710) may be implemented using any suitable techniques. In an embodiment, video encoder (303), video encoder (503), and video encoder (603), and video decoder (310), video decoder (410), and video decoder (710) may be implemented using one or more integrated circuits. In another embodiment, the video encoder (303), the video encoder (503), and the video encoder (603), and the video decoder (310), the video decoder (410), and the video decoder (710) may be implemented using one or more processors executing software instructions.

For blocks coded in non-subblock mode, the motion vector predictor list may be constructed as follows: (1) candidate predictors from spatial and temporal neighboring blocks; (2) candidate predictors from the HMVP buffer; (3) a candidate predictor from a pairwise average of existing motion vector predictors; (4) zero motion vector predictors for different reference pictures are used. Examples of these candidate predictors are described above.

When constructing the motion vector predictor list, a series of operations including an availability check and a redundancy check may be performed. The availability check checks whether a spatial or temporal neighboring block is encoded in inter prediction mode. The redundancy check checks whether the new motion vector predictor is identical to a copy of any existing motion vector predictor in the motion vector predictor list. For example, an availability check and a redundancy check are performed for the spatial and temporal candidates. A redundancy check is performed against the existing candidates. Furthermore, for existing spatial/temporal candidates, a redundancy check is performed for the candidates from the HMVP buffer. These operations may require multiple cycles to perform when the motion vector predictor list is long. In the worst case, a picture is divided into many small blocks. The total number of cycles required to complete the construction of the motion vector predictor list for all of these small blocks may be greater than desired. For example, the merge candidate list for each encoded block may be different from its neighboring blocks. Therefore, it is desirable to reduce the number of operations and simplify the construction process of the motion vector predictor list, especially for small blocks.

The present disclosure proposes improved techniques for simplifying the construction process of motion vector predictor lists when certain block size constraints are met (e.g., in merge mode, skip mode, or AMVP mode). That is, when a current block is treated as a small block, the construction process of the motion vector predictor list of the current block may be simplified so as to include a smaller number of motion vector predictors and/or perform fewer operations of availability check and/or redundancy check.

Various thresholds may be used to indicate a small block. In an embodiment, when the block area of the current block is less than or equal to a threshold, the current block may be considered as a small block. In another embodiment, when the current block is to be further divided into a plurality of smaller blocks and one of the plurality of smaller blocks is less than or equal to a threshold value, the current block is considered to be a small block. The threshold may be a preset number of luma samples, e.g., 32 or 64 luma samples. The threshold may correspond to a picture resolution of the current picture. For example, for pictures with high resolution, the threshold may be larger than for pictures with smaller resolution. Further, the threshold may be signaled in a bitstream or coded video sequence such as a Sequence Parameter Set (SPS), Picture Parameter Set (PPS), slice or tile header, etc.

According to aspects of the present disclosure, when a current block is treated as a small block, a construction process of a motion vector predictor list of the current block may be simplified such that a reduced number of motion vector predictors are included as compared to a block that is not treated as a small block.

Motion vector prediction classes such as spatial motion vector prediction, temporal motion vector prediction, and history-based motion vector prediction may each include multiple motion vector predictors. In an embodiment, when considering a current block as a small block, the number of motion vector predictors from one or more of these classes may be reduced. For example, for each motion vector prediction category, a subset of the respective plurality of motion vector predictors is included in the motion vector predictor list, such that the motion vector predictor list is shorter than if all motion vector predictors were included in the list. The subset of motion vector predictors may be the first N (e.g., N-1, 2, etc.) candidates from each class or some classes, where N is an integer less than the number of possible candidates for the respective class. However, in other embodiments, other predetermined candidates may be selected. The number N of each or some of the categories may be the same or different. Furthermore, the selection of the subset of motion vector predictors for each category or for certain categories may be the same or different. In one example, only the first N spatial and/or temporal candidates are allowed in the motion vector predictor list, where the number N is smaller than the number of possible spatial and temporal candidates. In some examples, N may be different for spatial and temporal candidates.

In an embodiment, for the spatial and temporal motion vector prediction classes, a subset of the spatial and temporal motion vector predictors are included in the motion vector predictor list, followed by the HMVP candidates and others. In another embodiment, the motion vector predictor list does not include any spatial and/or temporal motion vector predictors. I.e. spatial and/or temporal candidates are not allowed and the motion vector predictor list starts with HMVP candidates.

According to aspects of the present disclosure, when a current block is regarded as a small block, a construction process of a motion vector predictor list of the current block may be simplified such that fewer operations, such as a redundancy check operation, are performed. The redundancy check compares the new motion vector predictor with any existing motion vector predictor in the motion vector predictor list.

In an embodiment, one or more redundancy checks between two spatial and/or temporal candidates may be removed. For example, the motion vector predictor list does not perform a redundancy check between the possible spatial predictor values and the existing spatial motion vector predictors in the motion vector predictor list. In another example, the motion vector predictor list does not perform a redundancy check between the possible temporal motion vector predictor and the sum existing temporal motion vector predictor in the motion vector predictor list.

In an embodiment, one or more redundancy checks between a candidate from the HMVP buffer and an existing candidate from a spatially and/or temporally adjacent location may be removed. For example, the motion vector predictor list does not perform a redundancy check between the possible history-based motion vector predictor and an existing spatial motion vector predictor in the motion vector predictor list. In another example, the motion vector predictor list does not perform a redundancy check between the possible history-based motion vector predictor and an existing temporal motion vector predictor in the motion vector predictor list.

In an embodiment, no redundancy check is performed. That is, the motion vector predictor list is constructed without performing any redundancy check.

Fig. 8 shows a flowchart outlining an exemplary process (800) of a simplified motion vector predictor list construction process according to some embodiments of the present disclosure. In various embodiments, the process (800) is performed by processing circuitry such as: processing circuitry in the terminal devices (210), (220), (230), and (240), processing circuitry that performs the function of the video encoder (303), processing circuitry that performs the function of the video decoder (310), processing circuitry that performs the function of the video decoder (410), processing circuitry that performs the function of the intra prediction module (452), processing circuitry that performs the function of the video encoder (503), processing circuitry that performs the function of the predictor (535), processing circuitry that performs the function of the intra encoder (622), processing circuitry that performs the function of the intra decoder (772), and so on. In some embodiments, process (800) is implemented in software instructions, such that when processing circuitry executes software instructions, processing circuitry performs process (800).

The process (800) may generally begin at step (S801), where the process (800) determines whether the current block is to be further divided. If the current block is determined not to be further divided, the process (800) will proceed to step (S802), otherwise the process (800) will proceed to step (S803).

At step (S802), the process (800) determines whether the block area of the current block is less than or equal to a threshold. If it is determined that the block area of the current block is less than or equal to the threshold value, the process (800) proceeds to step (S805), otherwise the process (800) proceeds to step (S806).

At step (S803), the process (800) divides the current block into a plurality of smaller blocks, and then proceeds to step (S804).

At step (S804), the process (800) determines whether the block area of one of the smaller blocks is less than or equal to a threshold. The threshold may be a preset number of luminance samples or may correspond to the picture resolution of the current picture or may be signaled in the encoded video sequence. If it is determined that the block area of one of the smaller blocks is less than or equal to the threshold, the process (800) will proceed to step (S805), otherwise the process (800) will proceed to step (S806).

In some embodiments, step (S801) and/or step (S803) are optional and may not be performed. For example, if the decoded prediction information of the current block indicates a partition size of the current block, the partition size indicates that the current block is to be further divided into a plurality of smaller blocks. The process (800) will determine whether the partition size is less than or equal to a threshold. This step is the same as step (S804). If it is determined that the partition size is less than or equal to the threshold value, the process (800) will proceed to step (S805), otherwise, the process will proceed to step (S806). In another embodiment, the comparison of the blocks to the threshold is performed after any block partitioning has been performed.

At step (S805), the process (800) constructs a motion vector predictor list including a first number of motion vector predictors, and then proceeds to step (S807).

At step (S806), the process (800) builds a motion vector predictor list including a second number of motion vector predictors. The second number is greater than the first number. That is, the motion vector predictor list is simplified by reducing the second number of motion vector predictors to the first number of motion vector predictors, for example, in the manner described above. Then, the process (800) proceeds to step (S807).

At step (S807), the process (800) reconstructs the current block based on the motion vector predictor list. The process (800) then terminates.

Fig. 9 shows a flowchart outlining an exemplary process (900) according to some embodiments of the present disclosure. In various embodiments, the process (900) is performed by processing circuitry such as: processing circuitry in the terminal devices (210), (220), (230), and (240), processing circuitry that performs the function of the video encoder (303), processing circuitry that performs the function of the video decoder (310), processing circuitry that performs the function of the video decoder (410), processing circuitry that performs the function of the intra prediction module (452), processing circuitry that performs the function of the video encoder (503), processing circuitry that performs the function of the predictor (535), processing circuitry that performs the function of the intra encoder (622), processing circuitry that performs the function of the intra decoder (772), and so on. In some embodiments, process (900) is implemented in software instructions, such that when processing circuitry executes software instructions, processing circuitry performs process (900).

The process (900) may generally begin at step (S901), where the process (900) decodes prediction information for a current block in a current picture that is part of an encoded video sequence. After decoding the prediction information, the process (900) proceeds to step (S902).

At step (S902), the process (900) determines whether the area of the current block is less than or equal to a threshold. Then, the process (900) proceeds to step (S903). The threshold may be a preset number of luma samples, e.g., 32 or 64 luma samples. The threshold may correspond to a picture resolution of the current picture. The threshold may be signaled in the encoded video sequence.

At step (S903), the process (900) constructs a motion vector predictor list including a plurality of motion vector predictors. The number of motion vector predictors is based on whether an area of the current block is determined to be less than or equal to a threshold value. In an embodiment, the number of motion vector predictors included in the motion vector predictor list is a first number when it is determined that the area of the current block is less than or equal to a threshold value, and otherwise the number of motion vector predictors included in the motion vector predictor list is a second number, the second number being greater than the first number.

In some embodiments, the prediction information indicates that the current block is to be further divided into a plurality of smaller blocks, the process (900) divides the current block into the plurality of smaller blocks, and determines whether an area of one of the plurality of smaller blocks is less than or equal to a threshold. The process (900) also constructs a motion vector predictor list based on whether it is determined that an area of one of the smaller blocks is less than or equal to a threshold. When it is determined that the area of one of the plurality of smaller blocks is less than or equal to the threshold, the number of motion vector predictors included in the motion vector predictor list is a first number; otherwise, the number of motion vector predictors included in the motion vector predictor list is a second number.

In some embodiments, the prediction information indicates a partition size of the current block. In such embodiments, the process (900) determines whether the partition size is less than or equal to a threshold. The process (900) also constructs a motion vector predictor list based on whether the partition size is determined to be less than or equal to a threshold. When it is determined that the partition size is less than or equal to the threshold, the number of motion vector predictors included in the motion vector predictor list is a first number; otherwise, the number of motion vector predictors included in the motion vector predictor list is a second number.

In an embodiment, a motion vector predictor list comprising a first number of motion vector predictors is constructed based on a first set of spatial or temporal motion vector predictors. The first set of spatial or temporal motion vector predictors is smaller than a second set of spatial or temporal motion vector predictors used for constructing a motion vector predictor list comprising a second number of motion vector predictors.

In an embodiment, the motion vector predictor list comprising the first number of motion vector predictors does not comprise any spatial or temporal motion vector predictor.

In an embodiment, the number of redundancy checks used to construct the motion vector predictor list comprising the first number of motion vector predictors is reduced. For example, a first number of redundancy checks is performed to construct a motion vector predictor list including the first number of motion vector predictors, and a second number of redundancy checks is performed to construct a motion vector predictor list including the second number of motion vector predictors. The first number of redundancy checks is less than the second number of redundancy checks.

In an embodiment, the first number of redundancy checks does not include at least one of: (i) a comparison between a possible spatial motion vector predictor and a first existing spatial motion vector predictor in a list of motion vector predictors, (ii) a comparison between a possible temporal motion vector predictor and a first existing temporal motion vector predictor in a list of motion vector predictors, (iii) a comparison between a possible history-based motion vector predictor and a first existing spatial motion vector predictor or another existing spatial motion vector predictor in a list of motion vector predictors, and (iv) a comparison between a possible history-based motion vector predictor and a first existing temporal motion vector predictor or another existing temporal motion vector predictor in a list of motion vector predictors.

In an embodiment, a motion vector predictor list comprising a first number of motion vector predictors is constructed without performing any redundancy check.

In an embodiment, at least one of the motion vector predictors uses the current picture as a reference picture such that a reference block of the at least one of the motion vector predictors is within the current picture.

At step (S904), the process (900) reconstructs the current block based on the motion vector predictor list.

After reconstructing the current block, the process (900) terminates.

Although the above embodiments are based on reducing the number of redundancy checks in addition to reducing the number of motion vector predictors, it is noted that in other embodiments the number of redundancy checks may be reduced without reducing the number of motion vector predictors.

The motion vector prediction method may use a different picture from the current picture as a reference picture. However, motion vector prediction or block compensation may be performed from a previously reconstructed region within the current picture. Such motion vector prediction or block compensation may be referred to as intra picture block compensation, Current Picture Reference (CPR), or Intra Block Copy (IBC). In the IBC prediction mode, a displacement vector indicating an offset between a current block and a reference block within a current picture is referred to as a Block Vector (BV). The reference block has been reconstructed before the current block. Note that BV may be considered MV as discussed in this application.

The techniques described above may be implemented as computer software using computer readable instructions and physically stored on one or more computer readable media. For example, fig. 10 illustrates a computer system (1000) suitable for implementing certain embodiments of the presently disclosed subject matter.

The computer software may be encoded using any suitable machine code or computer language, which may be assembled, compiled, linked, etc., to create code comprising instructions that may be executed directly by one or more computer Central Processing Units (CPUs), Graphics Processing Units (GPUs), etc., or by interpretation, microcode execution, etc.

The instructions may be executed on various types of computers or components thereof, including, for example, personal computers, tablet computers, servers, smart phones, gaming devices, internet of things devices, and so forth.

The components illustrated in FIG. 10 for computer system (1000) are exemplary in nature and are not intended to suggest any limitation as to the scope of use or functionality of the computer software for implementing the embodiments disclosed herein. Neither should the configuration of components be interpreted as being dependent or limited to any one component or combination of components illustrated in the exemplary embodiments of the computer system (1000).

The computer system 1000 may include some human interface input devices. Such human interface input devices may be responsive to input by one or more human users, for example tactile input (such as keystrokes, sliding, data glove movement), audio input (such as speech, tapping), visual input (such as gestures), olfactory input (not shown). The human interface device may also be used to capture media that is not necessarily directly related to human conscious input, such as audio (e.g., speech, music, ambient sounds), images (e.g., scanned images, photographic images taken from still-image cameras), video (e.g., two-dimensional video, three-dimensional video including stereoscopic video).

The input human interface device may comprise one or more of the following (only one shown each): keyboard (1001), mouse (1002), touch pad (1003), touch screen (1010), data glove (not shown), joystick (1005), microphone (1006), scanner (1007), camera (1008).

The computer system (1000) may also include certain human interface output devices. Such human interface output devices may stimulate the perception of one or more human users through, for example, tactile output, sound, light, and smell/taste. The human interface output devices may include tactile output devices (such as those that generate tactile feedback using a touch screen (1010), a data glove (not shown), or a joystick (1005), but may also use tactile feedback devices that do not act as input devices), audio output devices (such as speakers (1009), headphones (not shown)), visual output devices (such as screens (1010) including CRT, LCD, plasma, OLED, each with or without touch screen input capability, each with or without tactile feedback capability — some of which may be capable of outputting two-dimensional visual output or more than three-dimensional output by means such as stereoscopic image output means; virtual reality glasses (not shown); holographic displays and canisters (not shown)), and printers (not shown). These visual output devices, such as a screen (1010), may be connected to the system bus (1048) through a graphics adapter (1050).

The computer system (1000) may also include human-accessible storage devices and their associated media, such as optical media including CD/DVD ROM/RW (1020) with CD/DVD and like media (1021), thumb drive (1022), removable hard or solid state drive (1023), conventional magnetic media such as tape and floppy disk (not shown), dedicated ROM/ASIC/PLD based devices such as secure dongle (not shown), and so forth.

Those skilled in the art will also appreciate that the term "computer-readable medium" used in connection with the presently disclosed subject matter does not encompass transmission media, carrier waves, or other transitory signals.

The computer system (1000) may also include an interface to one or more communication networks (1055). The one or more communication networks (1055) may be, for example, wireless, wired, optical. The network 1055 may also be local, wide area, metropolitan, on-board, and industrial, real-time, delay tolerant, etc. Examples of networks 1055 include: local area networks such as ethernet, wireless LANs, cellular networks including GSM, 3G, 4G, 5G, LTE, etc., television wired or wireless wide area digital networks including cable television, satellite television, and terrestrial broadcast television, in-vehicle and industrial networks including CANBus, etc. Some networks typically require an external network interface adapter that attaches to some universal data port or peripheral bus (1049) (e.g., a USB port of computer system (1000)); other networks are typically integrated into the core of the computer system (1000) by attaching to a system bus as described below, such as an ethernet interface to a PC computer system or a cellular network interface to a smartphone computer system. The computer system (1000) may communicate with other entities using any of these networks. Such communications may be uni-directional receive-only (e.g., broadcast television), uni-directional transmit-only (e.g., from the CAN bus to certain CAN bus devices), or bi-directional (e.g., to other computer systems using a local or wide area digital network). Certain protocols and protocol stacks may be used on each of the networks and network interfaces described above.

The aforementioned human interface device, human accessible storage device and network interface may be attached to the core (1040) of the computer system (1000).

The core (1040) may include one or more Central Processing Units (CPUs) (1041), Graphics Processing Units (GPUs) (1042), special purpose programmable processing units in the form of Field Programmable Gate Arrays (FPGAs) (1043), hardware accelerators (1044) for certain tasks, and the like. These devices may be connected together by a system bus (1048) along with Read Only Memory (ROM) (1045), random access memory (1046), internal mass storage devices (1047) such as internal non-user accessible hard drives, SSDs, etc. In some computer systems, the system bus (1048) may be accessed in the form of one or more physical plugs to enable expansion by additional CPUs, GPUs, and the like. The peripheral devices may be attached to the system bus (1048) of the core either directly or through a peripheral bus (1049). The architecture of the peripheral bus includes PCI, USB, etc.

The CPU (1041), GPU (1042), FPGA (1043) and accelerator (1044) may execute certain instructions, which may be combined to form the computer code described previously. The computer code may be stored in ROM (1045) or RAM (1046). Temporary data may also be stored in RAM (1046), while permanent data may be stored in, for example, an internal mass storage device (1047). Fast storage and retrieval of any of the storage devices may be achieved by using cache memory, which may be closely associated with one or more CPUs (1041), GPUs (1042), mass storage devices (1047), ROMs (1045), RAMs (1046), etc.

Computer readable media may have computer code thereon for performing various computer-implemented operations. The media and computer code may be those specially designed and constructed for the purposes of the present disclosure, or they may be of the kind well known and available to those having skill in the computer software arts.

By way of example, and not limitation, processor(s) (including CPUs, GPUs, FPGAs, accelerators, and the like) execute software contained in one or more tangible computer-readable media to enable a computer system having architecture (1000), and in particular cores (1040), to function. Such computer-readable media may be media associated with the user-accessible mass storage devices described above, as well as some storage devices having a non-transitory core (1040), such as an intra-core mass storage device (1047) or ROM (1045). Software implementing the various embodiments disclosed herein may be stored in such devices and newly executed (1040) by the cores. The computer readable medium may include one or more memory devices or chips, according to particular needs. The software may cause the core (1040), particularly the processors therein (including CPUs, GPUs, FPGAs, etc.), to perform certain processes described herein or certain portions thereof, including defining data structures stored in RAM (1046) and modifying the data structures according to the processes defined by the software. Additionally or alternatively, the computer system may function in a logically hardwired manner, or in another manner represented as circuitry (e.g., accelerator (1044)), which may operate in place of or in conjunction with software to perform certain processes described herein or certain portions thereof. Where appropriate, reference to software may encompass logic, and vice versa. Where appropriate, reference to a computer-readable medium may encompass circuitry, such as an Integrated Circuit (IC), that stores the executed software, circuitry that contains the executed logic, or both. The present disclosure encompasses any suitable combination of hardware and software.

While the present application has described several exemplary embodiments, there are alterations, permutations, and various substitute equivalents, which fall within the scope of the present disclosure. It will thus be appreciated that those skilled in the art will be able to devise various systems and methods which, although not explicitly shown or described herein, embody the principles disclosed herein and are thus within its spirit and scope.

Appendix A: acronyms

AMVP: advanced motion vector prediction

ASIC: application specific integrated circuit

BMS: reference setting

BS: strength of boundary

BV: block vector

CANBus: controller area network bus

CD: optical disk

CPR: current picture reference

A CPU: central processing unit

CRT: cathode ray tube having a shadow mask with a plurality of apertures

CTB: coding tree block

And (3) CTU: coding tree unit

CU: coding unit

DPB: decoder picture buffer

DVD: digital video CD

FPGA: field programmable gate area

GOP: picture group

GPU: graphics processing unit

GSM: global mobile communication system

HDR: high dynamic range

HEVC: efficient video coding

HRD: hypothetical reference decoder

IBC: intra-block replication

IC: integrated circuit with a plurality of transistors

JEM: joint exploration model

Local area network: local area network

LCD: liquid crystal display device with a light guide plate

LIC: local illumination compensation

LTE: long term evolution

MR-SAD: removing sum of absolute differences of means

MR-SATD: sum of absolute Hadamard transform differences with mean removed

MV: motion vector

An OLED: organic light emitting diode

PB: prediction block

PCI: peripheral component interconnect

PLD: programmable logic device

PPS: picture parameter set

PU (polyurethane): prediction unit

RAM: random access memory

ROM: read-only memory

SCC: screen content coding

SDR: standard dynamic range

SEI: supplemental enhancement information

SMVP: spatial motion vector predictor

SNR: signal to noise ratio

SPS: sequence parameter set

SSD: solid state disk

TMVP: temporal motion vector predictor

TU: conversion unit

USB: universal serial bus

VUI: video usability information

VVC: multifunctional video coding

Attached character

FIG. 1A

Related Art of Related Art

FIG. 1B

Related Art of Related Art

PLANAR MODE PLANE MODE

DC MODE DC MODE

FIG. 1C

Related Art of Related Art

111 Current Block

FIG. 1D

Related Art of Related Art

121 parity block

FIG. 1E

Related Art of Related Art

131 current block

FIG. 1F

Related Art of Related Art

152 parity block

151 parity block

149 movement shift

142 the current block

141 current picture

FIG. 1G

Related Art of Related Art

Load a tables with HMVP candidates Using HMVP candidate Load tables

Decode block with HMVP candidates to Decode block using HMVP candidates

Updating the table using the decoded motion information for Update of the table

FIG. 1H

Related Art of Related Art

Table before update

Redundancy candidates after Redundant check of Redundant candidates after Redundant filter redundancy check

Table after update

HMVP candidate index in the table

Redundant HMVP of Redundant HMVP

HMVP candidate to be added by HMVP candidate to be added

FIG. 2

250 network

FIG. 4

401 channel

431 receiver

415 buffer memory

420 resolver

421 symbol

451 scaler/inverse transform unit

452 Intra prediction

453 motion compensated prediction

456 loop filter

457 reference picture memory

458 current picture buffer

FIG. 5

SOURCE VIDEO SEQUENCE SOURCE-SOURCE VIDEO SOURCE-VIDEO SEQUENCE SOURCE-VIDEP-SOURCE-VIDEO

550 controller

530 source encoder

532 coding engine

535 predictor

534 reference picture memory

533 decoder

545 entropy encoder

540 transmitter

560 channel

FIG. 6

BLOCK DATA Block DATA

REFERENCE PICTURES reference Picture

GENERAL CONTROL DATA GENERAL-GENERAL CONTROL

Intraprediction RESULT in intra prediction

Intra prediction INFORMATION

INTER PREDICTION RESULT

INTER PREDICTION INFORMATION

CODED VIDEO SEQUENCE encoding VIDEO SEQUENCEs

621 universal controller

622 intra coder

624 residual encoder

625 entropy coder

628 residual decoder

630 interframe coder

FIG. 7

CODED VIDEO SEQUENCE encoding VIDEO SEQUENCEs

REFERENCE PICTURES reference Picture

Intra prediction INFORMATION

Intraprediction RESULT in intra prediction

INTER PREDICTION INFORMATION

INTER PREDICTION RESULT

RECONSTRUCTED PICTURE RECONSTRUE RECONSTRUCTED PICTURE RECONSTRUE PICTURE PICTUR

771 entropy decoder

772 Intra decoder

773 residual decoder

780 interframe decoder

774 reconstruction

FIG. 8

Start

S801 is the current block to be further divided?

S802 is the current block less than or equal to the threshold?

S803 divides the current block into a plurality of smaller blocks.

S804 is one smaller block smaller than or equal to the threshold?

S805 constructs a motion vector predictor list including the first number of motion vector predictors.

S806 constructs a motion vector predictor list including the second number of motion vector predictors. The second number is greater than the first number.

S807 reconstructs the current block based on the motion vector predictor list.

Stop

Yes is

No. No

FIG. 9

Start

S901 decodes prediction information of a current block in a current picture that is part of an encoded video sequence.

S902 determines whether the area of the current block is less than or equal to a threshold.

S903 constructs a motion vector predictor list including a plurality of motion vector predictors. The number of motion vector predictors is based on whether an area of the current block is determined to be less than or equal to a threshold value.

S904 reconstructs the current block based on the motion vector predictor list.

Stop

FIG. 10 shows a schematic view of a

1044 accelerator

1048 System bus

1050 graphics adapter

1054 network interface

1055 communication network