Encoding and decoding methods and corresponding devices

Patent metadata

Field	Value
Publication number	US-12355996-B2
Application number	US-202318198886-A
Country	US
Kind code	B2
Filing date	May 18, 2023
Priority date	Nov 23, 2017
Publication date	Jul 8, 2025
Grant date	Jul 8, 2025

Abstract

A decoding method is disclosed. First, context for a syntax element associated with a current transform coefficient of a block of a picture is determined. The context is determined based on the area of said block, on the position of the current transform coefficient within the block and on the number of non-zero neighboring transform coefficients in a local template. Second, the syntax element is decoded based at least on the determined context. Advantageously, the local template depends on the shape of said block.

First claim

The invention claimed is:

1. A method for decoding video data, comprising:
determining a context for a syntax element associated with a current transform coefficient of a current sub-block of a picture, the current sub-block resulting from a partitioning of a current block of samples according to a split mode selected from a plurality of split modes for splitting a block into at least one of rectangular sub-blocks or square sub-blocks, wherein the context is determined based on a value representative of an area of said current sub-block, a position of the current transform coefficient within the current sub-block, and transform coefficients in a local template, wherein the local template is a subset of transform coefficients of the current sub-block comprising transform coefficients in a causal neighborhood of the current transform coefficient, wherein, a position of at least one of the transform coefficients of the local template with respect to the current transform coefficient depends on a value representative of the shape of the current sub-block resulting from the partitioning of the current block of samples according to the selected split mode; and
decoding said syntax element based at least on the determined context.

2. The method of claim 1 , wherein said syntax element is a significant flag.

3. The method of claim 1 , wherein said local template comprises more transform coefficients along a direction of a longest dimension of the current sub-block.

4. The method of claim 1 , wherein the transform coefficients of the local template and said current transform coefficient form a horizontal rectangle in the case where the current sub-block is a horizontal rectangle and form a vertical rectangle in the case where the current sub-block is vertical rectangle.

5. The method of claim 1 , wherein the position of at least one of the transform coefficients of the local template with respect to the current transform coefficient further depends on a scan order of said current sub-block.

6. The method of claim 5 , wherein the transform coefficients of the local template and said current transform coefficient form a horizontal rectangle in the case where said scan order is horizontal and form a vertical rectangle in the case where said scan order is vertical.

7. A non-transitory storage medium carrying a software program including program code instructions for the method according to claim 1 .

8. A method for encoding video data, comprising:
determining a context for a syntax element associated with a current transform coefficient of a current sub-block of a picture, the current sub-block resulting from a partitioning of a current block of samples according to a split mode selected from a plurality of split modes for splitting a block into at least one of rectangular sub-blocks or square sub-blocks, wherein the context is determined based on a value representative of an area of said current sub-block, a position of the current transform coefficient within the current sub-block, and transform coefficients in a local template, wherein the local template is a subset of transform coefficients of the current sub-block comprising transform coefficients in a causal neighborhood of the current transform coefficient, wherein, a position of at least one of the transform coefficients of the local template with respect to the current transform coefficient depends on a value representative of the shape of the current sub-block resulting from the partitioning of the current block of samples according to the selected split mode; and
encoding said syntax element based at least on the determined context.

9. The method of claim 8 , wherein said syntax element is a significant flag.

10. The method of claim 8 , wherein said local template comprises more transform coefficients along a direction of a longest dimension of the current sub-block.

11. The method of claim 8 , wherein the transform coefficients of the local template and said current transform coefficient form a horizontal rectangle in the case where the current sub-block is a horizontal rectangle and form a vertical rectangle in the case where the current sub-block is vertical rectangle.

12. The method of claim 8 , wherein the position of at least one of the transform coefficients of the local template with respect to the current transform coefficient further depends on a scan order of said current sub-block.

13. The method of claim 12 , wherein the transform coefficients of the local template and said current transform coefficient form a horizontal rectangle in the case where said scan order is horizontal and form a vertical rectangle in the case where said scan order is vertical.

14. A non-transitory storage medium carrying a software program including program code instructions for the method according to claim 8 .

15. A device for decoding video data, the device comprising electronic circuitry adapted for:
determining a context for a syntax element associated with a current transform coefficient of a current sub-block of a picture, the current sub-block resulting from a partitioning of a current block of samples according to a split mode selected from a plurality of split modes for splitting a block into at least one of rectangular sub-blocks or square sub-blocks, wherein the context is determined based on a value representative of an area of said current sub-block, a position of the current transform coefficient within the current sub-block, and transform coefficients in a local template, wherein the local template is a subset of transform coefficients of the current sub-block comprising transform coefficients in a causal neighborhood of the current transform coefficient, wherein, a position of at least one of the transform coefficients of the local template with respect to the current transform coefficient depends on a value representative of the shape of the current sub-block resulting from the partitioning of the current block of samples according to the selected split mode; and
decoding said syntax element based at least on the determined context.

16. The device of claim 15 , wherein said syntax element is a significant flag.

17. The device of claim 15 , wherein said local template comprises more transform coefficients along a direction of a longest dimension of the current sub-block.

18. The device of claim 15 , wherein the transform coefficients of the local template and said current transform coefficient form a horizontal rectangle in the case where the current sub-block is a horizontal rectangle and form a vertical rectangle in the case where the current sub-block is vertical rectangle.

19. The device of claim 15 , wherein the position of at least one of the transform coefficients of the local template with respect to the current transform coefficient further depends on a scan order of said current sub-block.

20. The device of claim 19 , wherein the transform coefficients of the local template and said current transform coefficient form a horizontal rectangle in the case where said scan order is horizontal and form a vertical rectangle in the case where said scan order is vertical.

21. A device for encoding video data, the device comprising electronic circuitry adapted for:
determining a context for a syntax element associated with a current transform coefficient of a current sub-block of a picture, the current sub-block resulting from a partitioning of a current block of samples according to a split mode selected from a plurality of split modes for splitting a bloc

Assignees

• Interdigital Vc Holdings Inc

Inventors

• Leleannec Fabrice
• Poirier Tangi
• Chen Ya

Classifications

• H04N19/60

  using transform coding · CPC title

• H04N19/70

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

• H04N19/176

  the region being a block, e.g. a macroblock · CPC title

• H04N19/91

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

• H04N19/96

  Tree coding, e.g. quad-tree coding · CPC title