Coding data using an enhanced context-adaptive binary arithmetic coding (cabac) design

Patent metadata

Field	Value
Publication number	US-2016353113-A1
Application number	US-201615166153-A
Country	US
Kind code	A1
Filing date	May 26, 2016
Priority date	May 29, 2015
Publication date	Dec 1, 2016
Grant date	—

Abstract

A video coding device includes processor(s) configured to determine, for each of a plurality of bins of a value for a syntax element of a current transform coefficient, contexts using respective corresponding bins of values for the syntax element of previously coded transform coefficients. The processor(s) are configured to determine a context for an i th bin of the value for the syntax element of the current transform coefficient using a corresponding i th bin of a value for the syntax element of a previously coded transform coefficient. To use the corresponding i th bin of the value for the syntax element of the previously coded transform coefficient, the processor(s) are configured to use only the i th bin, and no other bins, of the value for the syntax element of the previously coded transform coefficient. ‘i’ represents a non-negative integer.

First claim

What is claimed is:

1 . A method of decoding video data, the method comprising:
for each of a plurality of bins of a value for a syntax element of a current transform coefficient, determining contexts using respective corresponding bins of values for the syntax element of one or more previously-decoded transform coefficients, wherein determining the contexts comprises determining a context for an i th bin of the value for the syntax element of the current transform coefficient using a corresponding i th bin of a value for the syntax element of a previously-decoded transform coefficient, wherein i comprises a non-negative integer, and wherein using the corresponding i th bin of the value for the syntax element of the previously-decoded transform coefficient comprises using only the i th bin of the value for the syntax element of the previously-decoded transform coefficient and no other bins of the value for the syntax element of the previously-decoded transform coefficient; and context adaptive binary arithmetic coding (CABAC) decoding the i th bin of the value for the syntax element of the current transform coefficient using the determined context.

2 . The method of claim 1 , wherein determining the context for the i th bin of the value for the syntax element of the current transform coefficient comprises determining the context for the i th bin of the value for the syntax element of the current transform coefficient using a template that identifies one or more neighboring transform coefficients to be used for CABAC decoding the current transform coefficient.

3 . The method of claim 2 , further comprising determining at least one of a size or a shape of the template based on at least one of a size of a transform unit that includes the current transform coefficient, a coding mode associated with a coding unit that includes including the transform unit, a position of the current transform coefficient in the transform unit that includes the current transform coefficient, or a position of the current transform coefficient in a coefficient group that includes the current transform coefficient.

4 . The method of claim 1 ,
wherein the current transform coefficient is included in a transform unit, wherein some or all bins of the transform unit are CABAC encoded according to a regular mode, and wherein CABAC decoding the i th bin of the value for the syntax element of the current transform coefficient comprises decoding the i th bin of the value for the syntax element of the current transform coefficient during an i th coding pass during which all corresponding i th bins of all transform coefficients of the transform unit are CABAC decoded.

5 . The method of claim 1 , wherein determining the context for the i th bin of the value for the syntax element of the current transform coefficient comprises determining a context index for the i th bin of the value for the syntax element of the current transform coefficient using a function of the previously-decoded transform coefficients.

6 . The method of claim 5 , wherein the previously-decoded transform coefficients are positioned in a template.

7 . The method of claim 5 , wherein using the function of the previously-decoded transform coefficients comprises using the function of a first ‘M’ previously-decoded transform coefficients, and wherein ‘M’ represents a non-negative value.

8 . The method of claim 5 ,
wherein the function comprises a summation function, and wherein the corresponding i th bin of the value for the syntax element of previously-decoded transform coefficient is included in a plurality of corresponding i th bins of values for syntax elements of a plurality of previously-decoded transform coefficients.

9 . The method of claim 8 , wherein determining the context index for the i th bin of the value for the syntax element of the current transform coefficient using the summation function comprises defining the context index for the i th bin of the value for the syntax element of the current transform coefficient as a sum of all of the plurality of the corresponding i th bins of values for the syntax elements of the plurality of the previously-decoded transform coefficients.

10 . The method of claim 8 , further comprising clipping a result of the summation function to form a clipped sum that is within a pre-defined range.

11 . The method of claim 1 , wherein determining the context for the i th bin of the value for the syntax element of the current transform coefficient comprises:
determining a context index for the i th bin of the value for the syntax element of the current transform coefficient; and adding an offset to the determined context index.

12 . The method of claim 11 , further comprising determining the offset based on a size of a transform unit that includes the current transform coefficient.

13 . The method of claim 12 , further comprising:
determining whether the transform unit is within a threshold size; and if the transform unit is within the threshold size, determining that the transform unit is associated with a set of context models that is common to all transform units that are within the threshold size.

14 . The method of claim 13 , wherein the threshold size is associated with a 16×16 dimensionality.

15 . The method of claim 1 , wherein the current transform coefficient is included in a transform unit that is encoded according to a bypass mode.

16 . A method of encoding video data, the method comprising:
for each of a plurality of bins of a value for a syntax element of a current transform coefficient, determining contexts using respective corresponding bins of values for the syntax element of one or more previously-encoded transform coefficients, wherein determining the contexts comprises determining a context for an i th bin of the value for the syntax element of the current transform coefficient using a corresponding i th bin of a value for the syntax element of a previously-encoded transform coefficient, wherein i comprises a non-negative integer, and wherein using the corresponding i th bin of the value for the syntax element of the previously-encoded transform coefficient comprises using only the i th bin of the value for the syntax element of the previously-encoded transform coefficient and no other bins of the value for the syntax element of the previously-encoded transform coefficient; and CABAC encoding the i th bin of the value for the syntax element of the current transform coefficient using the determined context.

17 . The method of claim 16 , wherein determining the context for the i th bin of the value for the syntax element of the current transform coefficient comprises determining the context for the i th bin of the value for the syntax element of the current transform coefficient using a template that identifies one or more neighboring transform coefficients to be used for CABAC decoding the current transform coefficient.

18 . The method of claim 17 , further comprising determining at least one of a size or a shape of the template based on at least one of a size of a transform unit that includes the current transform coefficient, a coding mode associated with a coding unit that includes including the transform unit, a position of the current transform coefficient in the transform unit that includes the current transform coefficient, or a position of the current transform coefficient in a coefficient group that includes the current transform coefficient.

19 . The method of claim 16 ,

Assignees

• Qualcomm Inc

Inventors

• Zhang Li
• Karczewicz Marta
• Chen Jianle
• Chien Wei-Jung

Classifications

• H04N19/157

  Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter · CPC title

• H04N19/436

  using parallelised computational arrangements · CPC title

• H04N19/174

  the region being a slice, e.g. a line of blocks or a group of blocks · CPC title

• H04N19/17

  the unit being an image region, e.g. an object · CPC title

• H04N19/122

  Selection of transform size, e.g. 8x8 or 2x4x8 DCT; Selection of sub-band transforms of varying structure or type · CPC title