AFFINE MOTION PREDICTION FOR VIDEO CODING

• US 20170332095A1
• Filed: 05/04/2017
• Published: 11/16/2017
• Est. Priority Date: 05/16/2016
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Zou, Feng, Chen, Jianle, Karczewicz, Marta, Li, Xiang, Chuang, Hsiao-Chiang, Chien, Wei-Jung
• Granted Patent: US 10,560,712 B2
• Time in Patent Office: Days
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/18 the unit being a set of transform coefficients
• CPC Class Codes: H04N 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• CPC Class Codes: H04N 19/513 Processing of motion vectors
• CPC Class Codes: H04N 19/52 by predictive encoding
• CPC Class Codes: H04N 19/537 Motion estimation other than block-based
• CPC Class Codes: H04N 19/567 Motion estimation based on rate distortion criteria
• CPC Class Codes: H04N 19/91 Entropy coding, e.g. variable length coding [VLC] or arithmetic coding

Abstract

An example method includes obtaining, for a current block of video data, values of motion vectors (MVs) of an affine motion model of a neighboring block of video data; deriving, from the values of the MVs of the affine motion model of the neighboring block, values of predictors for MVs of an affine motion model of the current block; decoding, from a video bitstream, a representation of differences between the values of the MVs of the affine motion model for the current block and the values of the predictors; determining the values of the MVs of the affine motion model for the current block from the values of the predictors and the decoded differences; determining, based on the determined values of the MVs of the affine motion model for the current block, a predictor block of video data; and reconstructing the current block based on the predictor block.

Claims

1. A method for decoding video data, the method comprising:

obtaining, by one or more processors of a video decoder and for a current block of video data, values of motion vectors of an affine motion model of a neighboring block of video data;

deriving, by the one or more processors and from the values of the motion vectors of the affine motion model of the neighboring block of video data, values of predictors for motion vectors of an affine motion model of the current block of video data;

decoding, by the one or more processors and from an encoded video bitstream, a representation of differences between the values of the motion vectors of the affine motion model for the current block of video data and the values of the predictors;

determining, by the one or more processors, the values of the motion vectors of the affine motion model for the current block of video data from the values of the predictors and the decoded differences;

determining, based on the determined values of the motion vectors of the affine motion model for the current block of video data, a predictor block of video data; and

reconstructing the current block of video data based on the predictor block of video data.

2. The method of claim 1, wherein the current block of video data is decoded using affine inter mode.

3. The method of claim 2, wherein the neighboring block of video data is decoded using affine inter mode or affine merge mode.

4. The method of claim 1, wherein the neighboring block of video comprises a selected neighboring block of video data, and wherein obtaining the values of the motion vectors of the affine motion model of the selected neighboring block of video data comprises:

evaluating, in a pre-defined order, neighboring blocks of video data of the current block of video data; and

selecting a first neighboring block of video data of the plurality of neighboring blocks of video data decoded using affine motion compensation as the selected neighboring block of video data.

5. The method of claim 1, further comprising:

determining, by the one or more processors, whether the affine motion model for the current block of video data comprises a four-parameter model that is convertible to two motion vectors or a six-parameter model that is convertible to three motion vectors.

6. The method of claim 5, wherein determining whether the affine motion model for the current block of video data comprises a four-parameter model or a six-parameter model comprises:

decoding, by the one or more processors and from the encoded video bitstream, a syntax element that indicates whether the affine motion model for the current block of video data comprises a four-parameter model or a six-parameter model.

7. The method of claim 6, wherein decoding the syntax element comprises decoding the syntax element from one or more of a video parameter set (VPS), sequence parameter set (SPS), picture parameter set (PPS), and a slice header referred to by the current block of video data.

8. The method of claim 6, wherein decoding the syntax element comprises decoding the syntax element from a coding unit (CU) that includes the current block of video data.

9. The method of claim 1, the method being executable on a wireless communication device, wherein the device comprises:

a memory configured to store the video data;

a processor configured to execute instructions to process the video data stored in the memory; and

a receiver configured to receive the video data and store the video data to the memory.

10. The method of claim 9, wherein the wireless communication device is a cellular telephone and the video data is received by the receiver and modulated according to a cellular communication standard.

11. A method for encoding video data, the method comprising:

determining, by one or more processors of a video encoder, values of motion vectors of an affine motion model of a current block of video data, the motion vectors of the affine motion model identifying a predictor block of video data for of the current block of video data;

obtaining, by the one or more processors, values of motion vectors of an affine motion model of a neighboring block of video data;

deriving, by the one or more processors and from the values of the motion vectors of the affine motion model of the neighboring block of video data, values of predictors for motion vectors of an affine motion model of the current block of video data; and

encoding, by the one or more processors and in an encoded video bitstream, a representation of differences between the values of the motion vectors of the affine motion model for the current block of video data and the values of the predictors.

12. The method of claim 11, wherein the current block of video data is encoded using affine inter mode.

13. The method of claim 12, wherein the neighboring block of video data is encoded using affine inter mode or affine merge mode.

14. The method of claim 11, wherein the neighboring block of video comprises a selected neighboring block of video data, and wherein obtaining the values of the motion vectors of the affine motion model of the selected neighboring block of video data comprises:

evaluating, in a pre-defined order, neighboring blocks of video data of the current block of video data; and

selecting a first neighboring block of video data of the plurality of neighboring blocks of video data decoded using affine motion compensation as the selected neighboring block of video data.

15. The method of claim 11, further comprising:

determining, by the one or more processors, whether the affine motion model for the current block of video data comprises a four-parameter model that is convertible to two motion vectors or a six-parameter model that is convertible to three motion vectors.

16. The method of claim 15, further comprising:

encoding, by the one or more processors and in the encoded video bitstream, a syntax element that indicates whether the affine motion model for the current block of video data comprises a four-parameter model or a six-parameter model.

17. The method of claim 16, wherein encoding the syntax element comprises encoding the syntax element in a video parameter set (VPS), sequence parameter set (SPS), picture parameter set (PPS), or a slice header referred to by the current block of video data.

18. The method of claim 16, wherein encoding the syntax element comprises encoding the syntax element in a coding unit (CU) that includes the current block of video data.

19. The method of claim 11, the method being executable on a wireless communication device, wherein the device comprises:

a memory configured to store the video data;

a processor configured to execute instructions to process the video data stored in the memory; and

a transmitter configured to transmit the encoded video bitstream.

20. The method of claim 19, wherein the wireless communication device is a cellular telephone and the encoded video bitstream is transmitted by the transmitted and modulated according to a cellular communication standard.

21. A device for decoding a block of video data, the device comprising:

a memory configured to store the video data; and

one or more processing units implemented in circuitry and configured to;

obtain, for a current block of video data, values of motion vectors of an affine motion model of a neighboring block of video data;

derive, from the values of the motion vectors of the affine motion model of the neighboring block of video data, values of predictors for motion vectors of an affine motion model of the current block of video data;

decode, from an encoded video bitstream, a representation of differences between the values of the motion vectors of the affine motion model for the current block of video data and the values of the predictors;

determine the values of the motion vectors of the affine motion model for the current block of video data from the values of the predictors and the decoded differences;

determine based on the determined values of the motion vectors of the affine motion model for the current block of video data, a predictor block of video data; and

reconstruct the current block of video data based on the predictor block of video data.

22. The device of claim 21, wherein the current block of video data is decoded using affine inter mode.

23. The device of claim 22, wherein the neighboring block of video data is decoded using affine inter mode or affine merge mode.

24. The device of claim 21, wherein the neighboring block of video comprises a selected neighboring block of video data, and wherein, to obtain the values of the motion vectors of the affine motion model of the selected neighboring block of video data, the one or more processing units are configured to:

evaluate, in a pre-defined order, neighboring blocks of video data of the current block of video data; and

select a first neighboring block of video data of the plurality of neighboring blocks of video data decoded using affine motion compensation as the selected neighboring block of video data.

25. The device of claim 21, wherein the one or more processing units are further configured to:

determine whether the affine motion model for the current block of video data comprises a four-parameter model that is convertible to two motion vectors or a six-parameter model that is convertible to three motion vectors.

26. The device of claim 25, wherein, to determine whether the affine motion model for the current block of video data comprises a four-parameter model or a six-parameter model, the one or more processing units are configured to:

decode, from the encoded video bitstream, a syntax element that indicates whether the affine motion model for the current block of video data comprises a four-parameter model or a six-parameter model.

27. The device of claim 26, wherein, to decode the syntax element, the one or more processing units are configured to decode the syntax element from one or more of a video parameter set (VPS), sequence parameter set (SPS), picture parameter set (PPS), and a slice header referred to by the current block of video data.

28. The device of claim 26, wherein, to decode the syntax element, the one or more processing units are configured to decode the syntax element from a coding unit (CU) that includes the current block of video data.

29. The device of claim 21, further comprising at least one of:

a display configured to display the reconstructed video data;

or

a camera configured to capture the video data.

30. The device of claim 21, wherein the device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

31. A device for encoding a block of video data, the device comprising:

a memory configured to store the video data; and

one or more processing units implemented in circuitry and configured to;

determine values of motion vectors of an affine motion model of a current block of video data, the motion vectors of the affine motion model identifying a predictor block of video data for of the current block of video data;

obtain values of motion vectors of an affine motion model of a neighboring block of video data;

derive, from the values of the motion vectors of the affine motion model of the neighboring block of video data, values of predictors for motion vectors of an affine motion model of the current block of video data; and

encode, in an encoded video bitstream, a representation of differences between the values of the motion vectors of the affine motion model for the current block of video data and the values of the predictors.

32. The device of claim 31, wherein the current block of video data is encoded using affine inter mode.

33. The device of claim 32, wherein the neighboring block of video data is encoded using affine inter mode or affine merge mode.

34. The device of claim 31, wherein the neighboring block of video comprises a selected neighboring block of video data, and wherein, to obtain the values of the motion vectors of the affine motion model of the selected neighboring block of video data, the one or more processing units are configured to:

evaluate, in a pre-defined order, neighboring blocks of video data of the current block of video data; and

select a first neighboring block of video data of the plurality of neighboring blocks of video data decoded using affine motion compensation as the selected neighboring block of video data.

35. The device of claim 31, wherein the one or more processing units are further configured to:

determine whether the affine motion model for the current block of video data comprises a four-parameter model that is convertible to two motion vectors or a six-parameter model that is convertible to three motion vectors.

36. The device of claim 35, wherein the one or more processing units are further configured to:

encode, in the encoded video bitstream, a syntax element that indicates whether the affine motion model for the current block of video data comprises a four-parameter model or a six-parameter model.

37. The device of claim 36, wherein, to encode the syntax element, the one or more processing units are configured to encode the syntax element in a video parameter set (VPS), sequence parameter set (SPS), picture parameter set (PPS), or a slice header referred to by the current block of video data.

38. The device of claim 36, wherein, to encode the syntax element, the one or more processing units are configured to encode the syntax element in a coding unit (CU) that includes the current block of video data.

39. The device of claim 31, further comprising at least one of:

a display configured to display the reconstructed video data;

or

a camera configured to capture the video data.

40. The device of claim 31, wherein the device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

41. A device for encoding or decoding video data, the device comprising:

means for obtaining, for a current block of video data, values of motion vectors of an affine motion model of a neighboring block of video data;

means for deriving, from the values of the motion vectors of the affine motion model of the neighboring block of video data, values of predictors for motion vectors of an affine motion model of the current block of video data;

means for obtaining differences between the values of the motion vectors of the affine motion model for the current block of video data and the values of the predictors;

means for determining each of the values of the motion vectors of the affine motion model for the current block of video data from the values of the predictors and the decoded differences; and

means for identifying, based on the determined values of the motion vectors of the affine motion model for the current block of video data, a predictor block of video data.

42. A computer-readable storage medium storing instructions that, when executed, cause one or more processors of a video encoder or a video decoder to:

obtain, for a current block of video data, values of motion vectors of an affine motion model of a neighboring block of video data;

derive, from the values of the motion vectors of the affine motion model of the neighboring block of video data, values of predictors for motion vectors of an affine motion model of the current block of video data;

obtain differences between the values of the motion vectors of the affine motion model for the current block of video data and the values of the predictors;

determine each of the values of the motion vectors of the affine motion model for the current block of video data from the values of the predictors and the decoded differences; and

identify, based on the determined values of the motion vectors of the affine motion model for the current block of video data, a predictor block of video data.