METHOD FOR MOTION VECTOR DIFFERENCE (MVD) AND INTRA BLOCK COPY VECTOR DIFFERENCE (BVD) CODING OF SCREEN CONTENT VIDEO DATA

• US 20150382010A1
• Filed: 06/25/2015
• Published: 12/31/2015
• Est. Priority Date: 06/30/2014
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Rapaka, Krishnakanth, Karczewicz, Marta, Pang, Chao, Sole Rojals, Joel
• Granted Patent: US 9,854,253 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04N 19/13 Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC]
• CPC Class Codes: H04N 19/139 Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/184 the unit being bits, e.g. of the compressed video stream
• CPC Class Codes: H04N 19/52 by predictive encoding

Abstract

A method for motion vector difference (MVD) coding of screen content video data is disclosed. In one aspect, the method includes determining an MVD between a predicted motion vector and a current motion vector and generating a binary string comprising n bins via binarizing the MVD. The method further includes determining whether an absolute value of the MVD is greater than a threshold value and encoding a subset of the n bins via an exponential Golomb code having an order that is greater than one in response to the absolute value of the MVD being greater than the threshold value.

Claims

1. A method operable by a video encoder for encoding screen content, the method comprising:

determining a motion vector (MVD) difference between a predicted motion vector and a current motion vector;

generating a binary string comprising n bins via binarizing the MVD;

encoding at least one bin of the n bins via a first entropy coding operation;

determining whether an absolute value of the MVD is greater than a threshold value; and

encoding a subset of the n bins via a second entropy coding operation in response to the absolute value of the MVD being greater than the threshold value, the second entropy coding operation comprising an exponential coding having an order that is greater than one.

2. The method of claim 1, wherein:

the first entropy coding operation comprises Context Adaptive Binary Arithmetic Coding (CABAC); and

the second entropy coding operation comprises an exponential Golomb coding.

3. The method of claim 2, further comprising determining a context for each of the at least one bin based on whether the MVD is a horizontal component MVD or a vertical component MVD.

4. The method of claim 1, wherein the at least one bin comprises first and second bins, the first bin indicating whether the absolute value of the MVD is greater than zero.

5. The method of claim 4, wherein the second bin indicates whether the absolute value of the MVD is greater than the threshold value.

6. The method of claim 4, wherein the subset of the n bins comprises third though n−

1^th bins of the n bins, the method further comprising encoding the third through n−

1^th bins using a fixed length code in response to the absolute value of the MVD being less than or equal to the threshold value, wherein the length of the fixed length code is equal to the threshold value.

7. The method of claim 4, wherein the subset of the n bins comprises third though n−

1^th bins of the n bins, the encoding the third through n−

1^th bins comprising encoding the third to n−

1^th bins in bypass mode.

8. The method of claim 1, further comprising encoding the n^th bin of the n bins in bypass mode, the n^th bin indicating a sign of the MVD.

9. The method of claim 1, wherein MVD is binarized and encoded via the same method as a block vector difference (BVD).

10. The method of claim 1, wherein the MVD comprises a plurality of directional components, the method further comprising generating a plurality of directional component binary strings respectively corresponding to the directional components via binarizing the directional components, the corresponding ordinal bins of the directional component binary strings sharing the same context.

11. The method of claim 1, wherein the at least one bin indicates whether the subset of the n bins are encoded via the second entropy coding operation or a fixed length code.

12. The method of claim 1, further comprising encoding at least a portion of the subset via a truncated Exponential Golomb coding in response to the absolute value of the MVD being less than or equal to the threshold value.

13. A method operable by a video decoder for decoding screen content, the method comprising:

receiving a bitstream comprising an encoded binary string, the binary string comprising n bins;

decoding at least one bin of the n bins via a first entropy coding operation, the at least one bin indicating whether an absolute value of a motion vector difference (MVD) is greater than a threshold value, the MVD being a difference between a predicted motion vector and a current motion vector;

decoding a subset of the n bins via a second entropy coding operation in response to the at least one bin indicating that the absolute value of the MVD is greater than the threshold value, the second entropy coding operation comprising an exponential coding having an order that is greater than one; and

generating the MVD based at least in part on the decoded bins.

14. The method of claim 13, wherein:

the first entropy coding operation comprises Context Adaptive Binary Arithmetic Coding (CABAC); and

the second entropy coding operation comprises an exponential Golomb coding.

15. The method of claim 13, wherein the at least one bin comprises first and second bins, the second bin indicating whether the absolute value of the MVD is greater than the threshold value, the first bin indicating whether the absolute value of the MVD is greater than zero.

16. The method of claim 13, further comprising decoding the subset of the n bins using a fixed length code in response to the at least one bin indicating that the absolute value of the MVD is less than or equal to the threshold value, wherein the length of the fixed length code is equal to the threshold value.

17. The method of claim 13, wherein the MVD is decoded via the same method as a block vector difference (BVD).

18. A device for encoding screen content, comprising:

a memory configured to store at least a portion of the screen content; and

at least one processor in communication with the memory and configured to;

determine a motion vector difference (MVD) between a predicted motion vector and a current motion vector;

generate a binary string comprising n bins via binarizing the MVD;

encode at least one bin of the n bins via a first entropy coding operation;

determine whether an absolute value of the MVD is greater than a threshold value; and

encode a subset of the n bins via a second entropy coding operation in response to the absolute value of the MVD being greater than the threshold value, the second entropy coding operation comprising an exponential coding having an order that is greater than one.

19. The device of claim 18, wherein:

the first entropy coding operation comprises Context Adaptive Binary Arithmetic Coding (CABAC); and

the second entropy coding operation comprises an exponential Golomb coding.

20. The device of claim 18, wherein the at least one bin comprises first and second bins, the first bin indicating whether the absolute value of the MVD is greater than zero.

21. The device of claim 20, wherein the second bin indicates whether the absolute value of the MVD is greater than the threshold value.

22. The device of claim 20, wherein the subset of the n bins comprises third though n−

1^th bins of the n bins, the at least one processor being further configured to encode the third through n−

1^th bins using a fixed length code in response to the absolute value of the MVD being less than or equal to the threshold value, wherein the length of the fixed length code is equal to the threshold value.

23. The device of claim 18, wherein the at least one processor is further configured to binarize and encode the MVD via the same method as a block vector difference (BVD).

24. The device of claim 18, wherein the at least one bin indicates whether the subset of the n bins are encoded via the second entropy coding operation or a fixed length code.

25. The device of claim 18, wherein the at least one processor is further configured to encode of the subset of the n bins via encoding at least a portion of the subset via a truncated Exponential Golomb coding in response to the absolute value of the MVD being less than or equal to the threshold value.

26. A device for decoding screen content, comprising:

a memory configured to store at least a portion of the screen content; and

at least one processor in communication with the memory and configured to;

receive a bitstream comprising an encoded binary string, the binary string comprising n bins;

decode at least one bin of the n bins via a first entropy coding operation, the at least one bin indicating whether an absolute value of a motion vector difference (MVD) is greater than a threshold value, the MVD being a difference between a predicted motion vector and a current motion vector;

decode a subset of the n bins via a second entropy coding operation in response to the at least one bin indicating that the absolute value of the MVD is greater than the threshold value, the second entropy coding operation comprising an exponential coding having an order that is greater than one; and

generate the MVD based at least in part on the decoded bins.

27. The device of claim 26, wherein:

the first entropy coding operation comprises Context Adaptive Binary Arithmetic Coding (CABAC); and

the second entropy coding operation comprises an exponential Golomb coding.

28. The device of claim 26, wherein the at least one bin comprises first and second bins, the second bin indicating whether the absolute value of the MVD is greater than the threshold value, the first bin indicating whether the absolute value of the MVD is greater than zero.

29. The device of claim 26, wherein the at least one processor is further configured to decode the subset of the n bins using a fixed length code in response to the at least one bin indicating that the absolute value of the MVD is less than or equal to the threshold value, wherein the length of the fixed length code is equal to the threshold value.

30. The device of claim 26, wherein the at least one processor is further configured to decode the MVD via the same method as a block vector difference (BVD).