Signaling syntax elements for transform coefficients for sub-sets of a leaf-level coding unit

Patent metadata

Field	Value
Publication number	US-9826238-B2
Application number	US-201213413475-A
Country	US
Kind code	B2
Filing date	Mar 6, 2012
Priority date	Jun 30, 2011
Publication date	Nov 21, 2017
Grant date	Nov 21, 2017

Abstract

This disclosure describes techniques for coding transform coefficients for a block of video data. According to these techniques, a video encoder divides a leaf-level unit of video data into a plurality of transform coefficient sub-sets. The video encoder generates, for a sub-set of the plurality of transform coefficient sub-sets, a syntax element that indicates whether or not the sub-set includes any non-zero coefficients. In some examples, the video encoder may selectively determine whether to generate the syntax element for each sub-set. A decoder may read an entropy encoded bit stream that includes the syntax element, and determine whether to decode the sub-set based on the syntax element.

First claim

The invention claimed is:

1. A method of encoding video data, the method comprising:
dividing a transform block of video data into a plurality of transform coefficient sub-sets;
determining, for each respective transform coefficient sub-set of the plurality of transform coefficient sub-sets, whether or not to generate a respective syntax element that indicates whether or not the respective transform coefficient sub-set includes any non-zero coefficients, wherein determining whether or not to generate the respective syntax element includes determining not to generate the respective syntax element for the respective transform coefficient sub-set where the respective transform coefficient sub-set includes a last non-zero coefficient of the transform block in a scan order;
generating the respective syntax element for each of the transform coefficient sub-sets of the plurality of transform coefficient sub-sets for which it was determined to generate the syntax element.

2. The method of claim 1 , further comprising:
determining a number of potential non-zero coefficients, wherein determining whether or not to generate the respective syntax element comprises comparing the number of potential non-zero coefficients of the respective transform coefficient sub-set to at least one threshold; and
if the number of potential non-zero coefficients of the respective transform coefficient sub-set is greater than the threshold, generating the respective syntax element with a value based on whether or not the respective transform coefficient sub-set includes any non-zero coefficients.

3. The method of claim 2 , wherein determining the number of potential non-zero coefficients comprises determining the number of potential non-zero coefficients based on how many coefficients of the respective transform coefficient sub-set have a position after the last non-zero coefficient of the transform block.

4. The method of claim 1 , wherein determining whether or not to generate the respective syntax element comprises:
determining, for a plurality of previously coded transform blocks of video data, an average number of non-zero coefficients included in the respective transform coefficient sub-set;
comparing the average number of non-zero coefficients included in the respective transform coefficient sub-set to a threshold; and
if the average number of non-zero coefficients is less than the threshold, generating the respective syntax element with a value based on whether or not the respective transform coefficient sub-set includes any non-zero coefficients.

5. A device configured to encode video data, the device comprising:
a memory configured to store video data; and
an integrated circuit configured to:
divide a transform block of video data into a plurality of transform coefficient sub-sets;
determine, for each respective transform coefficient sub-set of the plurality of transform coefficient sub-sets, whether or not to generate a respective syntax element that indicates whether or not the respective transform coefficient sub-set includes any non-zero coefficients, wherein, to determine whether or not to generate the respective syntax element, the integrated circuit is configured to determine not to generate the respective syntax element for the respective transform coefficient sub-set where the respective transform coefficient sub-set includes a last non-zero coefficient of the transform block in a scan order;
generate the respective syntax element for each of the transform coefficient sub-sets of the plurality of transform coefficient sub-sets for which it was determined to generate the syntax element.

6. The device of claim 5 , wherein the integrated circuit is further configured to:
determine a number of potential non-zero coefficients;
determine whether or not to generate the respective syntax element based on comparing the number of potential non-zero coefficients of the respective transform coefficient sub-set to at least one threshold; and
if the number of potential non-zero coefficients of the respective transform coefficient sub-set is greater than the threshold, generate the respective syntax element with a value based on whether or not the respective transform coefficient sub-set includes any non-zero coefficients.

7. The device of claim 6 , wherein the integrated circuit is configured to determine the number of potential non-zero coefficients based on how many coefficients of the respective transform coefficient sub-set have a position after the last non-zero coefficient of the transform block.

8. The device of claim 5 , wherein the integrated circuit is further configured to:
determine, for a plurality of previously coded transform blocks of video data, an average number of non-zero coefficients included in the respective transform coefficient sub-set;
compare the average number of non-zero coefficients included in the respective transform coefficient sub-set to a threshold; and
if the average number of non-zero coefficients is less than the threshold, generate the respective syntax element with a value based on whether or not the respective transform coefficient sub-set includes any non-zero coefficients.

9. A non-transitory computer-readable storage medium that stores instructions that, when executed, cause a computing device to:
divide a transform block of video data into a plurality of transform coefficient sub-sets;
determine, for each respective transform coefficient sub-set of the plurality of transform coefficient sub-sets, whether or not to generate a respective syntax element that indicates whether or not the respective transform coefficient sub-set of includes any non-zero coefficients, wherein the instructions that cause the computing device to determine whether or not to generate the respective syntax element comprise instructions that cause the computing device to determine not to generate the respective syntax element for the respective transform coefficient sub-set where the respective transform coefficient sub-set includes a last non-zero coefficient of the transform block in a scan order;
generate the respective syntax element for each of the transform coefficient sub-sets of the plurality of transform coefficient sub-sets for which it was determined to generate the syntax element.

10. The non-transitory computer-readable storage medium of claim 9 , wherein the instructions further cause the computing device to:
determine a number of potential non-zero coefficients;
determine whether or not to generate the respective syntax element based on comparing the number of potential non-zero coefficients of the respective transform coefficient sub-set to at least one threshold; and
if the number of potential non-zero coefficients of the respective transform coefficient sub-set is greater than the threshold, generate the respective syntax element with a value based on whether or not the respective transform coefficient sub-set includes any non-zero coefficients.

11. The non-transitory computer-readable storage medium of claim 10 , wherein the instructions further cause the computing device to:
determine the number of potential non-zero coefficients based on how many coefficients of the respective transform coefficient sub-set have a position after the last non-zero coefficient of the transform block.

12. The non-transitory computer-readable storage medium of claim 9 , wherein the instructions further cause the computing device to:
determine, for a plurality of previously coded transform blocks units of video data, an average number of non-zero coefficients included in the respective transform coefficient sub-set;
compare the average number of non-zero coef

Assignees

• Karczewicz Marta
• Wang Xianglin
• Guo Liwei
• Qualcomm Inc

Inventors

• Karczewicz Marta
• Wang Xianglin
• Guo Liwei

Classifications

• H04N19/129

  Scanning of coding units, e.g. zig-zag scan of transform coefficients or flexible macroblock ordering [FMO] · 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

• H04N19/61

  in combination with predictive coding · CPC title

• H04N19/14 Primary

  Coding unit complexity, e.g. amount of activity or edge presence estimation (H04N19/146 takes precedence) · CPC title

• H04N19/46

  Embedding additional information in the video signal during the compression process (H04N19/517, H04N19/68, H04N19/70 take precedence) · CPC title