Method for producing video coding and programme-product

Patent metadata

Field	Value
Publication number	US-9356620-B2
Application number	US-48965102-A
Country	US
Kind code	B2
Filing date	Sep 11, 2002
Priority date	Sep 14, 2001
Publication date	May 31, 2016
Grant date	May 31, 2016

Abstract

According to the invention, there are provided sets of contexts specifically adapted to encode special coefficients of a prediction error matrix, on the basis of previously encoded values of level k. Furthermore, the number of values of levels other than 0 is explicitly encoded and numbers of appropriate contexts are selected on the basis of the number of spectral coefficients other than 0.

First claim

The invention claimed is:

1. A method for video coding using symbols, the method performed by execution of a computer program stored on a non-transitory computer readable medium and comprising the steps of:
receiving a current image of a video data stream via a data input interface;
segmenting the received current image into a plurality of rectangular macro blocks;
comparing the rectangular macroblocks with respective macro blocks from one or more previously received reference images to calculate motion vectors, whereby previously received references images are stored in an image memory;
calculating a prediction image associated with movement of the macroblocks of the reference image based on the calculated motion vectors;
calculating a prediction error by subtracting the prediction image from the current image;
generating a prediction error matrix by transformation and quantization of the prediction error;
converting the prediction error matrix by coefficient sampling into a series of symbols;
performing context-adaptive arithmetic encoding of the symbols to form a bitstream, wherein the encoding includes for a symbol being encoded, selecting from different predetermined distributions of symbol frequencies a particular predetermined distribution of symbol frequencies based on the symbol encoded immediately beforehand, the predetermined distribution of symbol frequencies indicating the likelihood of different types of symbols occurring immediately following the type of the symbol encoded immediately beforehand based on known statistical interdependencies between different types of symbols occurring in succession; and
transmitting the bitstream formed by the context-adaptive arithmetic encoding of the symbols via a data output interface.

2. A method for video coding as claimed in claim 1 , wherein the prediction error matrix is converted by coefficient sampling into a series of levels and length of zero sequences.

3. A method for video coding as claimed in claim 2 , wherein the levels and lengths are represented as unary values.

4. A method for video coding as claimed in claim 2 , wherein the levels are arithmetically encoded context-adaptively in each case, with a distribution of underlying level value frequencies being selected depending on a level value encoded beforehand in each case.

5. A method for video coding as claimed in claim 2 , wherein the lengths are arithmetically encoded context-adaptively in each case, with a distribution of underlying length value frequencies being selected depending on a length value encoded beforehand in each case.

6. A method for video coding as claimed in claim 2 , wherein level values are sorted before the context-adaptive arithmetic encoding in accordance with level values.

7. A method for video coding as claimed in claim 1 , wherein the selection of the distribution of symbol frequencies is undertaken depending on the number of symbols read out.

8. A computer program, stored on a non-transitory computer readable medium, containing program code for executing a method for video coding using symbols, comprising the steps of:
receiving a current image of a video data stream via a data input interface;
segmenting the received current image into a plurality of rectangular macro blocks;
comparing the rectangular macroblocks with respective macro blocks from one or more previously received reference images to calculate motion vectors, whereby previously received references images are stored in an image memory;
calculating a prediction image associated with movement of the macroblocks of the reference image based on the calculated motion vectors;
calculating a prediction error by subtracting the prediction image from the current image;
generating a prediction error matrix by transformation and quantization of the prediction error;
converting the prediction error matrix by coefficient sampling into a series of symbols;
performing context-adaptive arithmetic encoding of the symbols to form a bitstream, wherein the encoding includes for a symbol being encoded, selecting from different predetermined distribution of symbol frequencies a particular predetermined distribution of symbol frequencies based on the symbol encoded immediately beforehand, the predetermined distributions of symbol frequencies indicating the likelihood of different types of symbols occurring immediately following the type of the symbol encoded immediately beforehand based on known statistical interdependencies between different types of symbols occurring in succession; and
transmitting the bitstream formed by the context-adaptive arithmetic encoding of the symbols via a data output interface.

9. A method for video coding as claimed in claim 1 , wherein the transformation of the prediction error is performed using a discrete cosine transformer.

10. An encoder for video coding using symbols, the encoder comprising:
a data input interface configured to receive a current image of a video data stream;
a movement estimation unit configured to segment the received current image into a plurality of rectangular macro blocks;
a movement estimation unit configured to compare the rectangular macroblocks with respective macro blocks from one or more previously received reference images to calculate motion vectors, whereby previously received references images are stored in an image memory;
a movement compensator configured to calculate a prediction image associated with movement of the macroblocks of the reference image based on the calculated motion vectors;
an error calculator configured to calculate a prediction error by subtracting the prediction image from the current image;
a transformer and quantizer configured to generate a prediction error matrix by transformation and quantization of the prediction error; and
a context-sensitive encoding unit configured to:
converting the prediction error matrix by coefficient sampling into a series of symbols corresponding to levels and lengths of zero sequences;
perform context-adaptive arithmetic encoding of the symbols to form a bitstream, wherein the encoding includes for a symbol being encoded, selecting from different predetermined distributions of symbol frequencies a particular predetermined distribution of symbol frequencies based on the symbol encoded immediately beforehand, the predetermined distribution of symbol frequencies indicating the likelihood of different types of symbols occurring immediately following the type of the symbol encoded immediately beforehand based on known statistical interdependencies between different types of symbols occurring in succession; and
output the bitstream formed by the context-adaptive arithmetic encoding of the symbols via a data input interface.

Assignees

• Bäse Gero
• Oertel Norbert
• Siemens Ag

Inventors

• Bäse Gero
• Oertel Norbert

Classifications

• H04N19/91

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

• H04N19/62

  by frequency transforming in three dimensions [3D] (H04N19/63 takes precedence) · CPC title

• H04N19/61 Primary

  in combination with predictive coding · CPC title

• H04N19/176

  the region being a block, e.g. a macroblock · CPC title

• H04N19/517

  by encoding · CPC title