Entropy decoding method using context information

Patent metadata

Field	Value
Publication number	US-9602843-B2
Application number	US-201214009150-A
Country	US
Kind code	B2
Filing date	Mar 30, 2012
Priority date	Apr 1, 2011
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

The present invention relates to an entropy decoding method and to a decoding apparatus using same. The entropy decoding method according to the present invention comprises: a step of decoding a bin of a syntax element; and a step of acquiring information on the syntax element based on the decoded bin. In the step of decoding the bin, context-based decoding or bypass decoding is performed for each bin of the syntax element.

First claim

The invention claimed is:

1. An entropy decoding method based on a context adaptive binary arithmetic coding, the method comprising:
deriving, by a decoding apparatus, context information on at least one bin among bins of a bin string for an intra_chroma_pred_mode syntax element;
decoding, by the decoding apparatus, the bins of the bin string, wherein a regular decoding is performed for the first bin among the bin string based on the context information and a bypass decoding is performed for the remaining bins among the bin string;
deriving, by the decoding apparatus, a value of the intra_chroma_pred_mode syntax element based on the decoded bins; and
generating, by the decoding apparatus, prediction samples based on the value of the intra_chroma_pred_mode syntax elements.

2. The method of claim 1 , wherein the step of decoding bins comprises applying the bypass decoding on the remaining bins of the bin string for the intra_chroma_pred_mode syntax element and applying contexts which are independent of each other to other bins of the bin string for the intra_chroma_pred_mode syntax element.

3. The method of claim 1 , wherein in the step of the decoding bins, independent context is applied to the first bin which is decoded based on the context information, and
wherein the independent context is a context which is updated independently from other context.

4. The method of claim 1 , wherein the step of decoding bins comprises:
determining whether the bypass decoding is performed on the remaining bins of the bin string for the intra_chroma_pred_mode syntax element; and
decoding the remaining bins based on the context information when it is determined that the bypass decoding is not performed on the remaining bins.

5. The method of claim 1 , wherein the step of decoding bins comprises decoding the first bin of the bin string for the intra_chroma_pred_mode syntax element based on a context index assigned to the first bin from a context index table which assigns a context index to a bin corresponding to the intra_chroma_pred_mode syntax element.

6. The method of the claim 1 , wherein, in the step of decoding bins, the first bin is decoded using a context index table,
wherein the context index table allocates an offset corresponding to a picture type for a picture to be decoded and context index for the first bin of the bin string for the intra_chroma_pred_mode syntax element, and
wherein the first bin of the bin string for the syntax element is decoded based on a context indicated by the context index and the offset.

7. The method of claim 1 , wherein a binary code of a bin is decoded as it is not using a context when the bypass decoding is performed.

8. The method of claim 1 , wherein, in the step of deriving context information, a bin index of 0 is allocated to the first bin, and the bypass decoding is performed on the remaining bins.

9. The method of claim 1 , wherein the intra_chroma_pred_mode syntax element specifies an intra prediction mode for a chroma sample.

10. The method of claim 1 , wherein the step of decoding bins comprises:
performing the regular decoding on the first bin of the bin string for the intra_chroma_pred_mode syntax element based on the context information; and
performing the bypass decoding on a second bin through the last bin of the bin string for the intra_chroma_pred_mode syntax element.

11. The method of claim 10 , wherein the context information is specified by a sum of context index of the first bin, and
wherein the context index offset has a value of 0 when a current slice is an I slice, a value of 1 when the current slice is a P slice, and a value of 2 when the current slice is a B slice.

Assignees

• Lim Jae Hyun
• Park Seung Wook
• Jeon Yong Joon
• Kim Chul Keun
• Choi Young Hee
• Kim Jung Sun
• Park Nae Ri
• Hendry Hendry
• Jeon Byeong Moon
• Park Joon Young
• Lg Electronics Inc

Inventors

• Lim Jae Hyun
• Park Seung Wook
• Jeon Yong Joon
• Kim Chul Keun
• Choi Young Hee
• Kim Jung Sun
• Park Nae Ri
• Hendry Hendry
• Jeon Byeong Moon
• Park Joon Young

Classifications

• H04N19/13 Primary

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

• H04N19/91 Primary

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

• H04N19/70

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

• H04N19/146

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

• H04N19/184

  the unit being bits, e.g. of the compressed video stream · CPC title