Enhanced intra-prediction mode signaling for video coding using neighboring mode

Patent metadata

Field	Value
Publication number	US-9654785-B2
Application number	US-201213491076-A
Country	US
Kind code	B2
Filing date	Jun 7, 2012
Priority date	Jun 9, 2011
Publication date	May 16, 2017
Grant date	May 16, 2017

Abstract

This disclosure describes techniques for intra-prediction mode signaling for video coding. In one example, a video coder is configured to determine, for a block of video data, a set of most probable intra-prediction modes such that the set of most probable intra-prediction modes has a size that is equal to a predetermined number that is greater than or equal to two. The video coder is also configured to code a value representative of an actual intra-prediction mode for the block based at least in part on the set of most probable intra-prediction modes and code the block using the actual intra-prediction mode. The video coder may further be configured to code the block using the actual intra-prediction mode, e.g., to encode or decode the block. Video encoders and video decoders may implement these techniques.

First claim

The invention claimed is:

1. A method of coding video data, the method comprising:
determining, by at least one processor for a block of video data, a set of most probable intra-prediction modes for predicting the block of video data from available intra-prediction modes for predicting the block of video data, wherein the set of most probable intra-prediction modes has a size that is equal to a predetermined number that is greater than or equal to two;
coding, by the at least one processor, a value indicating that an actual intra-prediction mode for the block of video data is included in the set of most probable intra-prediction modes; and
coding, by the at least one processor, the block of video data using the actual intra-prediction mode;
wherein determining the set of most probable intra-prediction modes further comprises:
determining, by the at least one processor, a first intra-prediction mode for a left-neighboring block of the block of video data,
determining, by the at least one processor, a second intra-prediction mode for an above-neighboring block of the block of video data,
when the first intra-prediction mode is different than the second intra-prediction mode, including, by the at least one processor, both the first intra-prediction mode and the second intra-prediction mode in the set of most probable intra-prediction modes,
when the first intra-prediction mode is the same as the second intra-prediction mode, and when the first and second intra-prediction modes comprise a mode other than a planar mode, including, by the at least one processor, the first intra-prediction mode and the planar mode in the set of most probable intra-prediction modes, and
when the first intra-prediction mode is the same as the second intra-prediction mode, and when the first and second intra-prediction modes comprise a planar mode, including, by the at least one processor, the planar mode and a DC mode in the set of most probable intra-prediction modes.

2. The method of claim 1 , wherein the block of video data comprises a luminance block, the method further comprising:
determining, by the at least one processor for a chrominance block corresponding to the luminance block, a mapping of a set of values to a set of intra-prediction modes, the set of intra-prediction modes comprising horizontal mode, vertical mode, planar mode, DC mode, and luma signal prediction mode, wherein when the actual intra-prediction mode for the luminance block comprises a mode other than horizontal mode, vertical mode, planar mode, or DC mode, the set of intra-prediction modes further comprises a reuse of luma intra-prediction mode mapped from a first value of the set of values, and wherein when the actual intra-prediction mode for the luminance block comprises one of horizontal mode, vertical mode, planar mode, or DC mode, the set of intra-prediction modes further comprises a mode other than horizontal mode, vertical mode, planar mode, or DC mode mapped from the first value of the set of values;
coding, by the at least one processor, a value representative of an actual intra-prediction mode for the chrominance block based on the mapping of the set of values to the set of modes; and
coding, by the at least one processor, the chrominance block using the actual intra-prediction mode for the chrominance block.

3. The method of claim 1 , further comprising:
determining, by the at least one processor, a prediction direction of the actual intra-prediction mode,
wherein determining the set of most probable intra-prediction modes further comprises including, by the at least one processor, at least one intra-prediction mode having a prediction direction closest to the prediction direction of the actual intra-prediction mode in the set of most probable intra-prediction modes.

4. The method of claim 1 , wherein the size of the set of most probable intra-prediction modes is equal to three.

5. The method of claim 4 , further comprising:
determining, by the at least one processor, a prediction direction of a first intra-prediction mode; and
comparing, by the at least one processor, the prediction direction of the first intra-prediction mode to prediction directions of one or more other available intra-prediction modes; and
wherein determining the set of most probable intra-prediction modes further comprises including, by the at least one processor, the first intra-prediction mode, a second intra-prediction mode of the one or more available intra-prediction modes, and a third intra-prediction mode of the one or more available intra-prediction modes in the set of most probable intra-prediction modes, wherein the second and third intra-prediction modes have prediction directions determined to be closest to the prediction direction of the first intra-prediction mode based on the comparison.

6. The method of claim 4 , wherein the set of three most probable intra-prediction modes includes DC mode, vertical mode, and planar mode.

7. The method of claim 1 , wherein:
the size of the set of most probable intra-prediction modes is equal to four,
when two of the most probable intra-prediction modes are the same, the set of four most probable intra-prediction modes comprises two available intra-prediction modes having prediction directions that are closest to a prediction direction of the same most probable intra-prediction mode, otherwise the most probable intra-prediction modes comprise at least one of the DC intra-prediction mode, the vertical intra-prediction mode, or the horizontal intra-prediction mode.

8. The method of claim 1 , further comprising:
selecting, by the at least one processor, the actual intra-prediction mode for the block of video data, and
wherein coding the block of video data further comprises encoding, by the at least one processor, the block of video data based on the actual intra-prediction mode.

9. The method of claim 1 , wherein:
coding the block of video data further comprises decoding, by the at least one processor, the block of video data using the actual intra-prediction mode, and
coding the value representative of the actual intra-prediction mode comprises determining, by the at least one processor, the actual intra-prediction mode from the value.

10. The method of claim 1 , wherein when the actual intra-prediction mode is the planar, vertical, horizontal, or DC mode, a chroma intra-prediction mode is an upper-right direction intra-prediction mode.

11. A device for coding video data, the device comprising:
a memory configured to store a block of video data; and
a video coder configured to:
determine, for the block of video data, a set of most probable intra-prediction modes for predicting the block of video data from available intra-prediction modes for predicting the block of video data, wherein the set of most probable intra-prediction modes has a size that is equal to a predetermined number that is greater than or equal to two, and
code a value indicating that an actual intra-prediction mode for the block of video data is included in the set of most probable intra-prediction modes, and code the block using the actual intra-prediction mode,
wherein determine the set of most probable intra-prediction modes further comprises that the video coder is configured to determine a first intra-prediction mode for a left-neighboring block of the block of video data, determine a second intra-prediction mode for an above-neighboring block of the block of video data, and when the first intra-prediction mode is different than the second intra-prediction mode, include both the first intra-prediction mode and the second intra-prediction mode in the set of most probable intra-prediction modes, when the first intr

Assignees

• Chien Wei-Jung
• Karczewicz Marta
• Wang Xianglin
• Qualcomm Inc

Inventors

• Chien Wei-Jung
• Karczewicz Marta
• Wang Xianglin

Classifications

• H04N19/186

  the unit being a colour or a chrominance component · CPC title

• H04N19/159 Primary

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

• H04N19/463

  by compressing encoding parameters before transmission · CPC title

• H04N19/46

  Embedding additional information in the video signal during the compression process (H04N19/517, H04N19/68, H04N19/70 take precedence) · CPC title

• H04N19/11

  among a plurality of spatial predictive coding modes · CPC title