Advanced arithmetic coder

Patent metadata

Field	Value
Publication number	US-2016353110-A1
Application number	US-201615166044-A
Country	US
Kind code	A1
Filing date	May 26, 2016
Priority date	May 29, 2015
Publication date	Dec 1, 2016
Grant date	—

Abstract

An example method of entropy coding video data includes determining a window size of a plurality of window sizes for a context of a plurality of contexts used in a context-adaptive coding process to entropy code a value for a syntax element of the video data; entropy coding, based on a probability state of the context, a bin of the value for the syntax element; updating a probability state of the context based on the window size and the coded bin. The example method also includes entropy coding a next bin with the same context based on the updated probability state of the context.

First claim

What is claimed is:

1 . A method for entropy coding of video data, the method comprising:
determining a window size of a plurality of window sizes for a context of a plurality of contexts used in a context-adaptive entropy coding process to entropy code a value for a syntax element of the video data; entropy coding, based on a probability state of the context, a bin of the value for the syntax element; and updating the probability state of the context based on the window size and the coded bin.

2 . The method of claim 1 , wherein the context-adaptive entropy coding process comprises a context-adaptive binary arithmetic coding (CABAC) process, or a context-adaptive variable length coding (CAVLC) process.

3 . The method of claim 1 , further comprising:
entropy coding another bin associated with the same context based on the updated probability state.

4 . The method of claim 1 , wherein the context is a first context, the method further comprising:
determining a window size of the plurality of window sizes for a second context of the plurality of contexts, wherein the window size of the second context is different than the window size of the first context.

5 . The method of claim 4 , wherein the window size for the first context and the window size for the second context are not signaled in a bitstream that includes the coded bin.

6 . The method of claim 1 , wherein the plurality of window sizes comprises a pre-defined set of window sizes.

7 . The method of claim 6 , wherein entropy coding comprises entropy encoding, and wherein determining the window size comprises:
determining, for respective window sizes of the pre-defined set of window sizes, respective quantities of bits used to entropy encode a particular bin string that includes the bin values for the syntax element; and selecting the window size of the pre-defined set of window sizes that corresponds to the smallest quantity of bits as the window size for the context to entropy encode the particular bin string.

8 . The method of claim 1 , further comprising:
coding a first syntax element that indicates whether a default window size is used for the plurality of contexts.

9 . The method of claim 8 , further comprising:
based on the first syntax element indicating that the default window size is not used for the plurality of contexts, coding a second syntax element that indicates the window size for the context.

10 . The method of claim 9 , wherein to indicate the window size for the context, the second syntax element indicates a difference between the window size for the context and the default window size.

11 . The method of claim 8 , wherein coding the first syntax element comprises coding a slice header of a current slice including the first syntax element, wherein the first syntax element indicates whether the default window size is used for the plurality of contexts when entropy coding bins of the current slice.

12 . The method of claim 1 , further comprising:
coding, in a slice header of a current slice, a syntax element that indicates whether window sizes for the plurality of contexts are inherited from a previously coded slice.

13 . The method of claim 1 , wherein determining the window size for the context comprises:
determining the window size for the context based on a type of the syntax element.

14 . The method of claim 1 , wherein entropy coding comprises entropy decoding, the method further comprising:
decoding, from a coded video bitstream, one or more syntax elements that indicate the window size for the context.

15 . An apparatus for entropy coding of video data, the apparatus comprising:
a memory configured to store a plurality of contexts used in a context-adaptive entropy coding process to entropy code a value for a syntax element of the video data; and one or more processors configured to:
determine a window size of a plurality of window sizes for a context of the plurality of contexts;
entropy code, based on a probability state of the context model, a bin of the value for the syntax element; and
update the probability state of the context model based on the window size the coded bin.

16 . The apparatus of claim 15 , wherein the one or more processors are further configured to:
entropy code another bin associated with the same context based on the updated probability state.

17 . The apparatus of claim 16 , wherein the context model is a first context, and wherein the one or more processors are further configured to:
determine a window size of the plurality of window sizes for a second context of the plurality of contexts, wherein the window size of the second context is different than the window size of the first context.

18 . The apparatus of claim 17 , wherein the window size for the first context and the window size for the second context are not signaled in a bitstream that includes the coded bin.

19 . The apparatus of claim 16 , wherein the plurality of window sizes comprises a pre-defined set of window sizes.

20 . The apparatus of claim 19 , wherein, to entropy code, the one or more processors are configured to entropy encode, and wherein, to determine the window size, the one or more processors are configured to:
determine, for respective window sizes of the pre-defined set of window sizes, respective quantities of bits used to entropy encode a particular bin string that includes the bin value for the syntax element; and select the window size of the pre-defined set of window sizes that corresponds to the smallest quantity of bits as the window size for the context to entropy encode the particular bin string.

21 . The apparatus of claim 15 , wherein the one or more processors are further configured to:
code a first syntax element that indicates whether a default window size is used for the plurality of contexts.

22 . The apparatus of claim 21 , wherein, based on the first syntax element indicating that the default window size is not used for the plurality of contexts, the one or more processors are further configured to:
code a second syntax element that indicates the window size for the context.

23 . The apparatus of claim 22 , wherein to indicate the window size for the context, the second syntax element indicates a difference between the window size for the context and the default window size.

24 . The apparatus of claim 21 , wherein, to code the first syntax element, the one or more processors are configured to code a slice header of a current slice including the first syntax element, wherein the first syntax element indicates whether the default window size is used for the plurality of context models when entropy coding bins of the current slice.

25 . The apparatus of claim 15 , wherein the one or more processors are further configured to:
code, in a slice header of a current slice, a syntax element that indicates whether window sizes for the plurality of contexts are inherited from a previously coded slice.

26 . The apparatus of claim 15 , wherein, to determine the window size for the context, the one or more processors are configured to:
determine the window size for the context based on a type of the syntax element.

27 . The apparatus of claim 15 , wherein the apparatus comprises at least one of:
an integrated circuit; a microprocessor; or a wireless communication device.

Assignees

• Qualcomm Inc

Inventors

• Zhang Li
• Chen Jianle
• Zhao Xin
• Li Xiang
• Liu Hongbin
• Chen Ying
• Karczewicz Marta

Classifications

• H04N19/146 Primary

  Data rate or code amount at the encoder output · CPC title

• H04N19/13 Primary

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

• H04N19/159

  Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction · CPC title

• H04N19/174

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

• H04N19/91

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