SEARCH REGION DETERMINATION FOR INTER CODING WITHIN A PARTICULAR PICTURE OF VIDEO DATA

• US 20160337661A1
• Filed: 05/10/2016
• Published: 11/17/2016
• Est. Priority Date: 05/11/2015
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Pang, Chao, Rapaka, Krishnakanth, Seregin, Vadim, Karczewicz, Marta, Joshi, Rajan Laxman
• Granted Patent: US 10,200,713 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04N 19/105 Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
• CPC Class Codes: H04N 19/182 the unit being a pixel
• CPC Class Codes: H04N 19/186 the unit being a colour or a chrominance component
• CPC Class Codes: H04N 19/503 involving temporal prediction adaptive coding with adaptive selection between spatial and temporal predictive coding H04N19/107; adaptive coding with adaptive selection among a plurality of temporal predictive coding modes H04N19/109
• CPC Class Codes: H04N 19/52 by predictive encoding
• CPC Class Codes: H04N 19/523 with sub-pixel accuracy
• CPC Class Codes: H04N 19/57 Motion estimation characterised by a search window with variable size or shape
• CPC Class Codes: H04N 19/593 involving spatial prediction techniques
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

An example method of encoding video data includes determining a resolution that will be used for a motion vector that identifies a predictor block in a current picture of video data for a current block in the current picture of video data; determining, based on the determined resolution, a search region for the current block such that a size of the search region is smaller where the resolution is fractional-pixel than where the resolution is integer-pixel; selecting, from within the search region, a predictor block for the current block; determining the motion vector that identifies the selected predictor block for the current block; and encoding, in a coded video bitstream, a representation of the motion vector.

Claims

1. A method of encoding video data, the method comprising:

determining a resolution that will be used for a vector that identifies a predictor block in a current picture of the video data for a current block in the current picture of video data;

determining, based on the determined resolution, a search region for the current block such that a size of the search region is smaller where the resolution is fractional-pixel than a size of the search region where the resolution is integer-pixel;

selecting, from within the search region, a predictor block for the current block;

determining the vector that identifies the selected predictor block for the current block; and

encoding, in a coded video bitstream, a representation of the vector.

2. The method of claim 1, wherein determining the search region for the current block comprises:

determining an initial search region; and

where the resolution that will be used for the vector is integer-pixel, determining that the initial search region is the search region for the current block;

or

where the resolution that will be used for the vector is fractional-pixel, determining the search region comprises;

reducing the initial search region by M samples from right and bottom boundaries of the initial search region; and

reducing the initial search region by N samples from top and left boundaries of the initial search region.

3. The method of claim 2, wherein M is 2 and N is 2.

4. The method of claim 2, wherein the vector is a chroma motion vector with fractional-pixel resolution, and wherein encoding the representation of the vector comprises encoding a luma motion vector from which the chroma motion vector is derivable.

5. The method of claim 1, wherein determining the resolution that will be used for the vector comprises determining a resolution that will be used for a chroma motion vector that identifies a chroma predictor block for the current block, the method further comprising:

determining that fractional-pixel resolution will be used for the vector where a ratio of chroma sampling relative to luma sampling for the current block is greater than one.

6. The method of claim 5, wherein the ratio of chroma sampling relative to luma sampling for the current block is greater than one where a chroma sampling format of the current block is 4:

2;

2 or 4;

2;

0.

7. The method of claim 1, further comprising:

encoding, in the coded video bitstream, a syntax element that indicates the resolution that will be used for the vector.

8. The method of claim 1, further comprising:

where the vector has fractional-pixel resolution, determining, using fractional-pixel interpolation and based at least in part on sample pixel values from outside of the predictor block, pixel values of the predictor block; and

reconstructing the current block based on the pixel values of the predictor block.

9. A method of decoding video data, the method comprising:

obtaining, from a coded video bitstream, a representation of a vector that identifies a predictor block in a current picture of the video data for a current block in the current picture of video data;

determining whether the vector has fractional-pixel resolution or integer-pixel resolution;

determining, based on the vector, a predictor block for the current block from within a search region having a size that is smaller where the resolution is fractional-pixel than a size of the search region where the resolution is integer-pixel;

in response to determining that the vector has fractional-pixel resolution, determining, using fractional-pixel interpolation and based at least in part on sample pixel values from outside of the predictor block, pixel values of the predictor block; and

reconstructing the current block based on the pixel values of the predictor block.

10. The method of claim 9, wherein:

when the vector has integer-pixel resolution, the search region for the current block comprises an initial search region,

when the vector has fractional-pixel resolution, the search region for the current block comprises a reduced search region determined by reducing the initial search region by M samples from right and bottom boundaries of the initial search region, and reducing the initial search region by N samples from top and left boundaries of the initial search region, and

performing fractional-pixel interpolation to determine the pixel values of the predictor block based at least in part on sample pixel values from outside of the initial search region but within the reduced search region.

11. The method of claim 10, wherein M is 2 and N is 2.

12. The method of claim 10, wherein the vector is a chroma motion vector, and wherein obtaining the representation of the motion vector comprises:

obtaining, from the coded video bitstream, a representation of luma motion vector; and

determining the chroma motion vector based on the luma motion vector.

13. The method of claim 9, wherein the vector is a chroma motion vector, the method further comprising:

determining that fractional-pixel resolution will be used for the chroma motion vector where a ratio of chroma sampling relative to luma sampling for the current block is greater than one.

14. The method of claim 13, wherein the ratio of chroma sampling relative to luma sampling for the current block is greater than one where a chroma sampling format of current block is 4:

2;

2 or 4;

2;

0.

15. The method of claim 9, further comprising:

decoding, from the coded video bitstream, a syntax element that indicates whether the vector has fractional-pixel resolution or integer-pixel resolution.

16. A device for encoding video data, the device comprising:

a memory configured to store a portion of the video data; and

one or more processors configured to;

determine a resolution that will be used for a vector that identifies a predictor block in a current picture of video data for a current block in the current picture of video data;

determine, based on the determined resolution, a search region for the current block such that a size of the search region is smaller where the resolution is fractional-pixel than where the resolution is integer-pixel;

select, from within the search region, a predictor block for the current block;

determine the vector that identifies the selected predictor block for the current block; and

encode, in a coded video bitstream, a representation of the vector.

17. The device of claim 16, wherein, to determine the search region for the current block, the one or more processors are configured to:

determine an initial search region that comprises a reconstructed region of the current picture; and

where the resolution that will be used for the vector is integer-pixel, determine that the initial search region is the search region for the current block;

or

where the resolution that will be used for the vector is fractional-pixel, determine the search region by at least;

reducing the initial search region by M samples from right and bottom boundaries of the initial search region; and

reducing the initial search region by N samples from top and left boundaries of the initial search region.

18. The device of claim 17, wherein M is 2 and N is 2.

19. The device of claim 17, wherein the vector is a chroma motion vector, and wherein, to encode the representation of the motion vector, the one or more processors are configured to encode a luma motion vector from which the chroma motion vector is derivable.

20. The device of claim 16, wherein, to determine the resolution that will be used for the vector, the one or more processors are configured to determine a resolution that will be used for a chroma motion vector that identifies a chroma predictor block for the current block, and wherein the one or more processors are further configured to:

determine that fractional-pixel resolution will be used for the chroma motion vector where a ratio of chroma sampling relative to luma sampling for the current block is greater than one.

21. The device of claim 20, wherein the ratio of chroma sampling relative to luma sampling for the current block is greater than one where a format of current block is 4:

2;

2 or 4;

2;

0.

22. The device of claim 16, wherein the one or more processors are further configured to:

encode, in the coded video bitstream, a syntax element that indicates the resolution that will be used for the vector.

23. The device of claim 16, wherein the one or more processors are further configured to:

where the vector has fractional-pixel resolution, determine, using fractional-pixel interpolation and based at least in part on sample pixel values from outside of the predictor block, pixel values of the predictor block; and

reconstruct the current block based on the pixel values of the predictor block.

24. An apparatus for encoding video data, the apparatus comprising:

means for determining a resolution that will be used for a vector that identifies a predictor block in a current picture of video data for a current block in the current picture of video data;

means for determining, based on the determined resolution, a search region for the current block such that a size of the search region is smaller where the resolution is fractional-pixel than where the resolution is integer-pixel;

means for selecting, from within the search region, a predictor block for the current block;

means for determining the vector that identifies the selected predictor block for the current block; and

means for encoding, in a coded video bitstream, a representation of the vector.

25. A computer-readable storage medium storing instructions that, when executed, cause one or more processors of a video encoding device to:

determine a resolution that will be used for a vector that identifies a predictor block in a current picture of video data for a current block in the current picture of video data;

determine, based on the determined resolution, a search region for the current block such that a size of the search region is smaller where the resolution is fractional-pixel than where the resolution is integer-pixel;

select, from within the search region, a predictor block for the current block;

determine the vector that identifies the selected predictor block for the current block; and

encode, in a coded video bitstream, a representation of the vector.

26. A device for decoding video data, the device comprising:

a memory configured to store a portion of the video data; and

one or more processors configured to;

obtain, from a coded video bitstream, a representation of a vector that identifies a predictor block in a current picture of the video data for a current block in the current picture of video data;

determine whether the vector has fractional-pixel resolution or integer-pixel resolution;

determine, based on the vector, a predictor block for the current block from within a search region having a size that is smaller where the resolution is fractional-pixel than where the resolution is integer-pixel;

in response to determining that the vector has fractional-pixel resolution, determine, using fractional-pixel interpolation and based at least in part on sample pixel values from outside of the predictor block, pixel values of the predictor block; and

reconstruct the current block based on the pixel values of the predictor block.

27. The device of claim 26, wherein:

when the vector has integer-pixel resolution, the search region for the current block comprises an initial search region, and

when the vector has fractional-pixel resolution the search region for the current block comprises the initial search region reduced by M samples from right and bottom boundaries of the initial search region, and reduced by N samples from top and left boundaries of the initial search region.

28. The device of claim 27, wherein M is 2 and N is 2.

29. The device of claim 27, wherein the vector is a chroma motion vector, and wherein, to obtain the representation of the chroma motion vector, the one or more processors are configured to:

obtain, from the coded video bitstream, a representation of luma motion vector; and

determine the chroma motion vector based on the luma motion vector.

30. The device of claim 26, wherein the vector is a chroma motion vector, and wherein the one or more processors are further configured to:

determine that fractional-pixel resolution will be used for the chroma motion vector where a ratio of chroma sampling relative to luma sampling for the current block is greater than one.

31. The device of claim 30, wherein the ratio of chroma sampling relative to luma sampling for the current block is greater than one where a format of current block is 4:

2;

2 or 4;

2;

0.

32. The device of claim 26, wherein the one or more processors are further configured to:

decode, from the coded video bitstream, a syntax element that indicates whether the vector has fractional-pixel resolution or integer-pixel resolution.

33. An apparatus for decoding video data, the apparatus comprising:

means for obtaining, from a coded video bitstream, a representation of a vector that identifies a predictor block in a current picture of video data for a current block in the current picture of video data;

means for determining whether the vector has fractional-pixel resolution or integer-pixel resolution;

means for determining, based on the vector, a predictor block for the current block from within a search region having a size that is smaller where the resolution is fractional-pixel than where the resolution is integer-pixel;

means for in response to determining that the vector has fractional-pixel resolution, determining, using fractional-pixel interpolation and based at least in part on sample pixel values from outside of the predictor block, pixel values of the predictor block; and

means for reconstructing the current block based on the pixel values of the predictor block.

34. A computer-readable storage medium storing instructions that, when executed, cause one or more processors of a video decoding device to:

obtain, from a coded video bitstream, a representation of a vector that identifies a predictor block in a current picture of video data for a current block in the current picture of video data;

determine whether the vector has fractional-pixel resolution or integer-pixel resolution;

determine, based on the vector, a predictor block for the current block from within a search region having a size that is smaller where the resolution is fractional-pixel than where the resolution is integer-pixel;

in response to determining that the vector has fractional-pixel resolution, determine, using fractional-pixel interpolation and based at least in part on sample pixel values from outside of the predictor block, pixel values of the predictor block; and

reconstruct the current block based on the pixel values of the predictor block.