Group flag in transform coefficient coding for video coding

Patent metadata

Field	Value
Publication number	US-9491463-B2
Application number	US-201313861319-A
Country	US
Kind code	B2
Filing date	Apr 11, 2013
Priority date	Apr 14, 2012
Publication date	Nov 8, 2016
Grant date	Nov 8, 2016

Abstract

A method of decoding data indicative of a subset of transform coefficients is described. The coefficients are indicative of a block of video data. The method may include determining that no transform coefficient in the subset of transform coefficients has an absolute value greater than one, and, based on the determining, skipping one or more decoding passes on the subset of transform coefficients, the decoding passes relating to decoding level information associated with the subset of transform coefficients.

First claim

What is claimed is:

1. A method of decoding data indicative of a subset of transform coefficients, the coefficients being indicative of residual data for a block of video data, the method comprising:
decoding one or more significance flags in the subset of transform coefficients;
determining that no transform coefficient in the subset of transform coefficients has an absolute value greater than one based on a first group flag, wherein the first group flag indicates whether or not the subset includes at least one transform coefficient with an absolute value greater than one in the case that the one or more significance flags indicate that the subset of transform coefficients includes at least one particular transform coefficient having an absolute value greater than zero; and
based on the determining, skipping one or more decoding passes on the subset of transform coefficients, the decoding passes relating to decoding level information associated with the subset of transform coefficients.

2. The method of claim 1 , further comprising:
decoding a greater-than-one flag for the transform coefficients in the subset of transform coefficients in the case that the first group flag indicates that the subset of transform coefficients includes at least one transform coefficient with an absolute value greater than one, wherein the greater-than-one flag indicates whether or not the particular transform coefficient has an absolute value greater than one,
wherein skipping one or more decoding passes on the subset of transform coefficients comprises not decoding the greater-than-one flag in the case that the first group flag indicates that the subset of transform coefficients does not include at least one transform coefficient with an absolute value greater than one.

3. The method of claim 2 , wherein skipping one or more decoding passes on the subset of transform coefficients further comprises not decoding a greater-than-two-flag and a level remaining syntax element in the case that the first group flag indicates that the subset of transform coefficients does not include at least one transform coefficient with an absolute value greater than one.

4. The method of claim 1 , further comprising:
decoding a second group flag indicating whether or not the subset of transform coefficients includes any transform coefficients with an absolute value greater than two in the case that one or more greater-than-one flags or the first group flag indicates at least one transform coefficient has an absolute value greater than one; and
decoding a greater-than-two flag for the transform coefficients in the subset of transform coefficients indicated as having an absolute value larger than one in the case that the second group flag indicates that the subset of transform coefficients includes transform coefficients with an absolute value greater than two, wherein the greater-than-two flag indicates whether or not the particular transform coefficient has an absolute value greater than two, and
wherein skipping one or more decoding passes on the subset of transform coefficients comprises not decoding the greater-than-two flag in the case that the second group flag indicates that the subset of transform coefficients does not include transform coefficients with an absolute value greater than two.

5. The method of claim 4 , wherein skipping one or more decoding passes on the subset of transform coefficients further comprises not decoding a level remaining syntax element in the case that the second group flag indicates that the subset of transform coefficients does not include transform coefficients with an absolute value greater than two.

6. The method of claim 1 , wherein decoding the first group flag comprises:
inferring a value of the first group flag based on one or more predetermined criteria.

7. The method of claim 6 , wherein the predetermined criteria includes a presence of a DC coefficient in the subset of transform coefficients.

8. The method of claim 6 , wherein the predetermined criteria includes a threshold number of significant coefficients in the subset of transform coefficients.

9. A method of encoding data indicative of a subset of transform coefficients, the coefficients being indicative of residual data for a block of video data, the method comprising:
encoding one or more significance flags in the subset of transform coefficients;
determining that no transform coefficient in the subset of transform coefficients has an absolute value greater than one;
encoding a first group flag indicating whether or not the subset includes at least one transform coefficient with an absolute value greater than one in the case that the one or more significance flags indicate that the subset of transform coefficients includes at least one particular transform coefficient having an absolute value greater than zero; and
based on the determining, skipping one or more encoding passes on the subset of transform coefficients, the encoding passes relating to encoding level information associated with the subset of transform coefficients.

10. The method of claim 9 , further comprising:
encoding a greater-than-one flag for the transform coefficients in the subset of transform coefficients in the case that the first group flag indicates that the subset of transform coefficients includes at least one transform coefficient with an absolute value greater than one, wherein the greater-than-one flag indicates whether or not the particular transform coefficient has an absolute value greater than one,
wherein skipping one or more encoding passes on the subset of transform coefficients comprises not encoding the greater-than-one flag in the case that the first group flag indicates that the subset of transform coefficients does not include at least one transform coefficient with an absolute value greater than one.

11. The method of claim 10 , wherein skipping one or more encoding passes on the subset of transform coefficients further comprises not encoding a greater-than-two-flag and a level remaining syntax element in the case that the first group flag indicates that the subset of transform coefficients does not include at least one transform coefficient with an absolute value greater than one.

12. The method of claim 9 , further comprising:
encoding a second group flag indicating whether or not the subset of transform coefficients includes any transform coefficients with an absolute value greater than two in the case that one or more greater-than-one flags or the first group flag indicates at least one transform coefficient has an absolute value greater than one; and
encoding a greater-than-two flag for the transform coefficients in the subset of transform coefficients indicated as having an absolute value larger than one in the case that the second group flag indicates that the subset of transform coefficients includes transform coefficients with an absolute value greater than two, wherein the greater-than-two flag indicates whether or not the particular transform coefficient has an absolute value greater than two, and
wherein skipping one or more encoding passes on the subset of transform coefficients comprises not encoding the greater-than-two flag in the case that the second group flag indicates that the subset of transform coefficients does not include transform coefficients with an absolute value greater than two.

13. The method of claim 12 , wherein skipping one or more encoding passes on the subset of transform coefficients further comprises not encoding a level remaining syntax element in the case that the second group flag indicates that the subset of transform coefficients does not include tra

Assignees

• Qualcomm Inc

Inventors

• Sole Rojals Joel
• Joshi Rajan Laxman
• Chien Wei-Jung
• Chen Jianle
• Seregin Vadim
• Karczewicz Marta

Classifications

• H04N19/14

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

• H04N19/13

  Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC] · CPC title

• H04N19/615 Primary

  using motion compensated temporal filtering [MCTF] · CPC title

• H04N19/18

  the unit being a set of transform coefficients · CPC title

• H04N19/70 Primary

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