Escape sample coding in palette-based video coding

Patent metadata

Field	Value
Publication number	US-10038915-B2
Application number	US-201514719215-A
Country	US
Kind code	B2
Filing date	May 21, 2015
Priority date	May 22, 2014
Publication date	Jul 31, 2018
Grant date	Jul 31, 2018

Abstract

In an example, a method of processing video data includes determining a value of a block-level syntax element that indicates, for all samples of a block of video data, whether at least one respective sample of the block is coded based on a color value of the at least one respective sample not being included in a palette of colors for coding the block of video data. The method also includes coding the block of video data based on the value.

First claim

What is claimed is:

1. A method of processing video data, the method comprising:
determining a value of a block-level syntax element, wherein the block-level syntax element corresponds to an entirety of a block of the video data that includes a plurality of samples, and wherein the value of the block-level syntax element indicates whether at least one respective sample of the plurality of samples included in the block is coded using a color value of the at least one respective sample not being included in a palette of color values for coding the block of video data; and
coding the block of video data based on the value of the block-level syntax element.

2. The method of claim 1 , wherein determining the value of the block-level syntax element comprises determining a value of a block-level escape flag that indicates whether at least one respective sample of the block is coded as an escape sample.

3. The method of claim 2 , wherein the block of the video data comprises a coding unit (CU) of the video data, and wherein determining the value of the block-level escape flag comprises determining the value of the block-level escape flag for the CU.

4. The method of claim 3 , further comprising:
coding palette entries associated with the color values of the palette for the CU; and
coding the block-level escape flag for the CU after coding the palette entries associated with the color values of the palette.

5. The method of claim 3 , further comprising:
coding the block-level escape flag for the CU; and
coding palette entries associated with the color values of the palette for the CU after coding the block-level escape flag for the CU.

6. The method of claim 3 , further comprising conditionally coding the block-level escape flag for the CU based on a size of the CU, wherein conditionally coding the block-level escape flag for the CU comprises only coding the block-level escape flag when the size of the CU exceeds a threshold size.

7. The method of claim 1 , further comprising:
determining, based on the value of the block-level syntax element, that all samples of the plurality of samples included in the block are coded according to the color values of the palette;
determining that a palette size that indicates a number of palette indices included in the palette of color values for the block is equal to one; and
based on the determined palette size being equal to one, coding all samples of the block based on the one index of the palette and without coding any other syntax for the block that indicates palette indices for the block.

8. The method of claim 7 , wherein coding the block without coding any other syntax for the block that indicates palette indices for the block comprises coding the block without coding at least one of data that indicates a palette mode associated with coding the block, data that indicates index values of the palette of color values for the block, or data that indicates a run of palette indices of the palette.

9. The method of claim 1 , further comprising:
determining that a palette size that indicates a number of palette indices of the palette for the block is equal to zero; and
based on the determined palette size being equal to zero, determining the value of the block-level syntax element at least in part by inferring the value of the block-level syntax element, wherein inferring the value of the block-level syntax element comprises determining the value of the block-level syntax element without coding the block-level syntax element, and wherein the inferred value of the block-level syntax element indicates that all samples of the block are coded based on color value information not included in the palette.

10. The method of claim 9 , wherein coding the block of the video data comprises coding, based on the determined palette size being zero indices, all samples of the plurality of samples included in the block using the color value information that is not included in the palette and without coding any other syntax for the block that indicates palette indices for the palette of color values for the block of the video data.

11. The method of claim 10 , wherein coding the block without coding any other syntax for the block that indicates palette indices for the block comprises coding the block without coding at least one of data that indicates a palette mode associated with coding the block, data that indicates palette indices of the palette of color values for the block, or data that indicates a run of palette indices of the palette.

12. The method of claim 1 , wherein coding the block of the video data comprises encoding the block of the video data, and wherein encoding the block of the video data based on the value of the block-level syntax element comprises:
based on the determined value of the block-level syntax element indicating that the at least one respective sample of the plurality of samples included in the block is to be encoded using the color value of the at least one respective sample not being included in the palette of colors, entropy encoding respective index values for all samples of the plurality of samples included in the block, wherein the respective index values identify respective entries of the palette, and wherein one of the respective index values indicates an escape sample that is to be encoded using the color value that is not included in the palette of colors; and
signaling the respective index values of the palette in an encoded bitstream.

13. The method of claim 1 , wherein coding the block of the video data comprises decoding the block of the video data, and wherein decoding the block of the video data based on the value of the block-level syntax element comprises:
obtaining, from an encoded bitstream, respective index values of a palette of color values for the block for the plurality of samples included in the block of the video data, wherein each of the respective index values identifies a respective entry of the palette of color values;
and
based on the determined value of the block-level syntax element indicating that the at least one respective sample of the plurality of samples included in the block is to be decoded using the color value of the at least one respective sample not being included in the palette of colors:
entropy decoding values for all samples of the plurality of samples included in the block by matching the respective index values to at least one of the entries of the palettes; and
entropy decoding the at least one sample using the respective color value that is not included in the palette of color values.

14. A device for processing video data, the device comprising:
a memory configured to store a block of video data, the block including a plurality of samples; and
one or more processors in communication with the memory, the one or more processors being configured to:
determine a value of a block-level syntax element, wherein the block-level syntax element corresponds to an entirety of a block of the video data that includes a plurality of samples, and wherein the value of the block-level syntax element indicates whether at least one respective sample of the plurality of samples included in the block of the video data stored to the memory is coded using a color value of the at least one respective sample not being included in a palette of color values for coding the block of video data; and
code the block of video data stored to the memory based on the value of the block-level syntax element.

15. The device of claim 14 , wherein to determine the value of the block-level syntax element, the one or more processors are config

Assignees

• Qualcomm Inc

Inventors

• Joshi Rajan Laxman
• Seregin Vadim
• Pu Wei
• Karczewicz Marta
• Sole Rojals Joel
• Rapaka Krishnakanth

Classifications

• H04N19/91

  Entropy coding, e.g. variable length coding [VLC] or arithmetic coding · CPC title

• H04N19/132

  Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking · CPC title

• H04N19/70

  characterised by syntax aspects related to video coding, e.g. related to compression standards · CPC title

• H04N19/186 Primary

  the unit being a colour or a chrominance component · CPC title

• H04N19/93

  Run-length coding · CPC title