Video encoding device, video decoding device, video encoding method, video decoding method, video encoding or decoding program

Patent metadata

Field	Value
Publication number	US-9521433-B2
Application number	US-67620708-A
Country	US
Kind code	B2
Filing date	Sep 5, 2008
Priority date	Sep 6, 2007
Publication date	Dec 13, 2016
Grant date	Dec 13, 2016

Abstract

Intended is to obtain a video encoding device, a video encoding method, and a video encoding program which enable to prevent reduction in compression efficiency caused by drastic changes in symbol occurrence probabilities in context adaptive coding, and a video decoding device, a video decoding method and a decoding program corresponding thereto.
The video data 101 is input into video encoding device on a macroblock basis, and after quantization, the PCM determination unit 139 determines whether the coded data 123 is PCM mode or not. Even when the coded data 123 is PCM mode, the context updating unit 301 executes context updating processing so as to improve efficiency of binary arithmetic coding. According to the determination of PCM mode or non PCM mode, the third switch 148 supplies either binary arithmetic coding output or PCM coding output as its output data.

First claim

What is claimed is:

1. A video encoding device, comprising:
a first encoding unit for subjecting transformed and quantized values which are obtained by applying frequency-transform and quantization to an image block, to binary arithmetic coding which is entropy coding based on contexts, and updating said contexts based on data of being target to encode;
a second encoding unit for encoding said image block by an encoding method which is different from the method of said first encoding unit and is non-entropy encoding;
an output data selection unit for selecting either first output data output by said first encoding unit or second output data output by said second encoding unit; and
a context updating unit for, when the output data selection unit selects said second output data encoded by the non-entropy coding, updating said contexts for use in the binary arithmetic coding of said transformed and quantized values by increasing least-probable-symbol occurrence probabilities of said contexts with respect to least-probable-symbol so that symbol occurrence probabilities of the context coincide occurrence probabilities of bin, which is the least-probable-symbol, in the coded data before the next entropy coding being execute.

2. The video encoding device according to claim 1 , wherein said context updating unit is a unit which updates contexts for use in the binary arithmetic coding of said transformed and quantized values so as to decrease the number of contexts associated with low least-probable-symbol occurrence probabilities.

3. The video encoding device according to claim 1 , wherein said context updating unit is a unit which increases occurrence probabilities of least-probable-symbols of contexts for use in the binary arithmetic coding of said transformed and quantized values.

4. The video encoding device according to claim 1 , wherein said context updating unit is a unit which writes contexts associated with predetermined certain values of symbol occurrence probabilities over contexts for use in the binary arithmetic coding of said transformed and quantized values.

5. The video encoding device according to claim 4 , wherein said predetermined certain values of symbol occurrence probabilities are the value of equal probability.

6. The video encoding device according to claim 1 , wherein the encoding method different from the method of said first encoding unit is PCM coding.

7. A video encoding method, comprising:
a first encoding step of subjecting transformed and quantized values which are obtained by applying frequency-transform and quantization to an image block to binary arithmetic coding which is entropy coding based on contexts, and updating said contexts based on data of being target to encode;
a second encoding step of encoding said image block by an encoding method which is different from the method of said first encoding step and is non-entropy encoding;
an output data selection step of selecting either first output data output at said first encoding step or second output data output at said second encoding step; and
a context updating step of, when at the output data selection step, said second output data encoded by the non-entropy coding is selected, updating said contexts for use in the binary arithmetic coding of said transformed and quantized values by increasing least-probable-symbol occurrence probabilities of said contexts with respect to least-probable-symbol so that symbol occurrence probabilities of the context coincide occurrence probabilities of bin, which is the least-probable-symbol, in the coded data before the next entropy coding being execute.

8. The video encoding method according to claim 7 , wherein the coding method different from the method of said first encoding step is PCM coding.

9. The video encoding method according to claim 7 , wherein at said context updating step, updating contexts for use in the binary arithmetic coding of said transformed and quantized values so as to decrease the number of contexts having low least-probable-symbol occurrence probabilities.

10. The video encoding method according to claim 7 , wherein at said context updating step, increasing occurrence probabilities of least-probable-symbols of contexts for use in the binary arithmetic coding of said transformed and quantized values.

11. The video encoding method according to claim 7 , wherein at said context updating step, writing contexts associated with predetermined certain values of symbol occurrence probabilities over contexts for use in the binary arithmetic coding of said transformed and quantized values.

12. The video encoding method according to claim 11 , wherein said predetermined certain values of symbol occurrence probabilities are the value of equal probability.

13. The video encoding device according to claim 1 , wherein said context updating unit updates contexts for use in the binary arithmetic coding of said transformed and quantized values by setting most-probable-symbol occurrence probabilities of contexts to low probability.

14. The video encoding method according to claim 7 , wherein at said context updating step, updating contexts for use in the binary arithmetic coding of said transformed and quantized values is by setting most-probable-symbol occurrence probabilities of contexts to low probability.

Assignees

• Chono Keiichi
• Miyamoto Yoshihiro
• Nec Corp

Inventors

• Chono Keiichi
• Miyamoto Yoshihiro

Classifications

• H04N19/196

  being specially adapted for the computation of encoding parameters, e.g. by averaging previously computed encoding parameters (processing of motion vectors H04N19/513) · CPC title

• H04N19/136

  Incoming video signal characteristics or properties · CPC title

• H04N19/21

  with binary alpha-plane coding for video objects, e.g. context-based arithmetic encoding [CAE] · CPC title

• H04N19/91

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

• H04N19/93 Primary

  Run-length coding · CPC title