Context initialization based on slice header flag and slice type

Patent metadata

Field	Value
Publication number	US-12489902-B2
Application number	US-202519258498-A
Country	US
Kind code	B2
Filing date	Jul 2, 2025
Priority date	Jun 30, 2011
Publication date	Dec 2, 2025
Grant date	Dec 2, 2025

Abstract

Technique for initialization of encoders and decoders. In some cases, the decoder receives a slice and identifies if the slice is either a forward predicted B-slice or a backward predicted B-slice, and not both a forward and backward predicted B-slice, and based upon this identification initializes, using a P-slice technique, a context associated with the slice.

First claim

The invention claimed is:

1 . An encoding apparatus comprising at least one processor comprising processor circuitry configured individually and/or collectively to:
encode, in a bitstream, a presence flag indicating that an initialization flag is not included in the bitstream; for a slice of a picture, select initialization values for initializing an arithmetic coding; based on the presence flag indicating that the initialization flag is not included in the bitstream, select a first set of initialization values in response to a slice type of the slice being a B slice type, and select a second set of initialization values in response to the slice type of the slice being a P slice type; initialize the arithmetic coding using the selected initialization values; and encode one or more syntax elements of the slice using the arithmetic coding.

2 . The encoding apparatus of claim 1 , wherein the presence flag is in a picture parameter set.

3 . The encoding apparatus of claim 1 , wherein the arithmetic coding is context-based adaptive binary arithmetic coding (CABAC).

4 . The encoding apparatus of claim 1 , wherein to initialize the arithmetic coding, the at least one processor is further configured individually and/or collectively to:
set context models using the selected initialization values.

5 . A video encoding method comprising:
encoding, in a bitstream, a presence flag indicating that an initialization flag is not included in the bitstream; for a slice of a picture, selecting initialization values for initializing an arithmetic coding; based on the presence flag indicating that the initialization flag is not included in the bitstream, selecting a first set of initialization values in response to a slice type of the slice being a B slice type, and selecting a second set of initialization values in response to the slice type of the slice being a P slice type; initializing the arithmetic coding using the selected initialization values; and encoding one or more syntax elements of the slice using the arithmetic coding.

6 . The video encoding method of claim 5 , wherein the presence flag is in a picture parameter set.

7 . The video encoding method of claim 5 , wherein the arithmetic coding is context-based adaptive binary arithmetic coding (CABAC).

8 . The video encoding method of claim 5 , wherein initializing the arithmetic coding further comprises:
setting context models using the selected initialization values.

9 . A decoding apparatus comprising at least one processor comprising processor circuitry configured individually and/or collectively to:
decode, from a bitstream, a presence flag indicating that an initialization flag is not included in the bitstream; for a slice of a picture, select initialization values for initializing an arithmetic coding; based on the presence flag indicating that the initialization flag is not included in the bitstream, select a first set of initialization values in response to a slice type of the slice being a B slice type, and select a second set of initialization values in response to the slice type of the slice being a P slice type; initialize the arithmetic coding using the selected initialization values; and decode one or more syntax elements of the slice using the arithmetic coding.

10 . The decoding apparatus of claim 9 , wherein the presence flag is in a picture parameter set.

11 . The decoding apparatus of claim 9 , wherein the arithmetic coding is context-based adaptive binary arithmetic coding (CABAC).

12 . The decoding apparatus of claim 9 , wherein to initialize the arithmetic coding, the at least one processor is further configured individually and/or collectively to:
set context models using the selected initialization values.

13 . A video decoding method comprising:
decoding, from a bitstream, a presence flag indicating that an initialization flag is not included in the bitstream; for a slice of a picture, selecting initialization values for initializing an arithmetic coding; based on the presence flag indicating that the initialization flag is not included in the bitstream, selecting a first set of initialization values in response to a slice type of the slice being a B slice type, and selecting a second set of initialization values in response to the slice type of the slice being a P slice type; initializing the arithmetic coding using the selected initialization values; and decoding one or more syntax elements of the slice using the arithmetic coding.

14 . The video decoding method of claim 13 , wherein the presence flag is in a picture parameter set.

15 . The video decoding method of claim 13 , wherein the arithmetic coding is context-based adaptive binary arithmetic coding (CABAC).

16 . The video decoding method of claim 13 , wherein initializing the arithmetic coding further comprises:
setting context models using the selected initialization values.

Assignees

• Velos Media Llc

Inventors

• Misra Kiran
• Segall Christopher

Classifications

• H04N19/70

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

• H04N19/44

  Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder · CPC title

• H04N19/172

  the region being a picture, frame or field · CPC title

• H04N19/174

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

• H04N19/577

  Motion compensation with bidirectional frame interpolation, i.e. using B-pictures · CPC title