Entropy coding of motion vector differences

Patent metadata

Field	Value
Publication number	US-9743090-B2
Application number	US-201715419006-A
Country	US
Kind code	B2
Filing date	Jan 30, 2017
Priority date	Jun 16, 2011
Publication date	Aug 22, 2017
Grant date	Aug 22, 2017

Abstract

An entropy decoder is configured to, for horizontal and vertical components of motion vector differences, derive a truncated unary code from the data stream using context-adaptive binary entropy decoding with exactly one context per bin position of the truncated unary code, which is common for horizontal and vertical components of the motion vector differences, and an Exp-Golomb code using a constant equi-probability bypass mode to obtain the binarizations of the motion vector differences. A desymbolizer is configured to debinarize the binarizations of the motion vector difference syntax elements to obtain integer values of the horizontal and vertical components of the motion vector differences. A reconstructor is configured to reconstruct a video based on the integer values of the horizontal and vertical components of the motion vector differences.

First claim

What is claimed:

1. A decoder for decoding a video from a data stream, comprising:
a desymbolizer configured to debinarize binarizations of horizontal and vertical components of motion vector differences, wherein the video is predictively coded by motion compensated prediction using motion vectors, the horizontal and vertical components of the motion vector differences representing a prediction error with respect to the motion vectors, and
each of the binarizations of the horizontal and vertical components including a prefix bin string having fixed-length binary codes based on a cutoff value, and a suffix bin string having an Exp-Golomb code, wherein a first fixed-length binary code of the prefix bin string indicates whether an absolute value of a motion vector difference is greater than zero and a second fixed-length binary code of the prefix bin string indicates whether the absolute value of the motion vector difference is greater than one, and wherein the cutoff value is two and the Exp-Golomb code has order one; and
a reconstructor configured to reconstruct the video based on the debinarized values of the horizontal and vertical components of the motion vector differences.

2. The decoder of claim 1 , the reconstructor is configured to spatially and/or temporally predict the horizontal and vertical components of motion vectors so as to acquire predictors for the horizontal and vertical components of the motion vectors and reconstruct the horizontal and vertical components of the motion vectors by refining the predictors using the horizontal and vertical components of the motion vector differences.

3. The decoder of claim 1 , wherein the reconstructor is configured to predict the horizontal and vertical components of motion vectors in different manners so as to obtain an ordered list of predictors for the horizontal and vertical components of motion vectors, obtain an list index from the data stream and reconstruct the horizontal and vertical components of motion vectors by refining the predictor to which a predictor of the list to which the list index points using the horizontal and vertical components of the motion vector differences.

4. The decoder of claim 1 , wherein the reconstructor is configured to reconstruct the video using the motion-compensated prediction by applying the horizontal and vertical components of motion vectors at a spatial granularity defined by a sub-division of the video's pictures in blocks, wherein the reconstructor uses merging syntax elements present in the data stream so as to group the blocks into merge groups and apply the debinarized values of the horizontal and vertical components of the motion vector differences obtained by the desymbolizer, in units of merge groups.

5. The decoder of claim 4 , wherein the reconstructor is configured to derive the sub-division of the video's pictures in blocks from a portion of the data stream excluding the merging syntax elements.

6. The decoder of claim 4 , wherein the reconstructor is configured to adopt the horizontal and vertical components of a predetermined motion vector for all blocks of an associated merge group, or refine same by the horizontal and vertical components of the motion vector differences associated with the blocks of the merge group.

7. The decoder of claim 1 , wherein the data stream comprises at least a portion associated with color samples of the video.

8. The decoder of claim 1 , wherein the data stream comprises at least a portion associated with depth values related to a depth map associated with the video.

9. The decoder of claim 1 , further comprising an entropy decoder configured to decode at least the fixed-length binary codes using binary arithmetic decoding.

10. The decoder of claim 9 , wherein the entropy decoder is configured to, for each motion vector difference, decoder the fixed-length binary codes of the horizontal and vertical components of the respective motion vector difference, prior to the Exp-Golomb code of the horizontal and vertical components of the respective motion vector difference.

11. A method for decoding a video from a data stream, comprising:
debinarizing binarizations of horizontal and vertical components of motion vector differences, wherein the video is predictively coded by motion compensated prediction using motion vectors, the horizontal and vertical components of the motion vector differences representing a prediction error with respect to the motion vectors, and
each of the binarizations of the horizontal and vertical components including a prefix bin string having fixed-length binary codes based on a cutoff value, and a suffix bin string having an Exp-Golomb code, wherein a first fixed-length binary code of the prefix bin string indicates whether an absolute value of a motion vector difference is greater than zero and a second fixed-length binary code of the prefix bin string indicates whether the absolute value of the motion vector difference is greater than one, and wherein the cutoff value is two and the Exp-Golomb code has order one; and
reconstructing the video based on the debinarized values of the horizontal and vertical components of the motion vector differences.

12. The method of claim 11 , the reconstructing including spatially and/or temporally predicting the horizontal and vertical components of motion vectors so as to acquire predictors for the horizontal and vertical components of the motion vectors and reconstructing the horizontal and vertical components of the motion vectors by refining the predictors using the horizontal and vertical components of the motion vector differences.

13. The method of claim 11 , the reconstructing including predicting the horizontal and vertical components of motion vectors in different manners so as to obtain an ordered list of predictors for the horizontal and vertical components of motion vectors, obtaining an list index from the data stream and reconstructing the horizontal and vertical components of motion vectors by refining the predictor to which a predictor of the list to which the list index points using the horizontal and vertical components of the motion vector differences.

14. The method of claim 11 , the reconstructing including reconstructing the video using the motion-compensated prediction by applying the horizontal and vertical components of motion vectors at a spatial granularity defined by a sub-division of the video's pictures in blocks, wherein merging syntax elements present in the data stream are used so as to group the blocks into merge groups and apply the debinarized values of the horizontal and vertical components of the motion vector differences, in units of merge groups.

15. The method of claim 14 , the reconstructing further including deriving the sub-division of the video's pictures in blocks from a portion of the data stream excluding the merging syntax elements.

16. The method of claim 14 , the reconstructing further including adopting the horizontal and vertical components of a predetermined motion vector for all blocks of an associated merge group, or refine same by the horizontal and vertical components of the motion vector differences associated with the blocks of the merge group.

17. The method of claim 11 , wherein the data stream comprises at least a portion associated with color samples of the video.

18. The method of claim 11 , wherein the data stream comprises at least a portion associated with depth values related to a depth map associated with the video.

19. The method of claim 11 , further comprising entropy decoding the f

Assignees

• Ge Video Compression Llc

Inventors

• George Valeri
• Bross Benjamin
• Kirchhoffer Heiner
• Marpe Detlev
• Nguyen Tung
• Preiss Matthias
• Siekmann Mischa
• Stegemann Jan
• Wiegand Thomas

Classifications

• H04N19/126

  Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers · CPC title

• H04N19/13 Primary

  Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC] · CPC title

• H04N19/52

  by predictive encoding · CPC title

• H03M7/4075 Primary

  Golomb codes · CPC title

• H03M7/42

  using table look-up for the coding or decoding process, e.g. using read-only memory {(H03M7/4006 takes precedence)} · CPC title