# US 12,120,335 B2 · Hardware friendly design for intra mode coding

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- Number: US 12,120,335 B2
- Document ID: US12120335B2
- Status: Granted
- Kind: B2
- Application number: 17/573,856
- Filed: 2022-01-12
- Published: 2023-03-09
- Granted: 2024-10-15
- Earliest claimed: 2021-08-24
- Assignees: Tencent America LLC
- Applicants: Tencent America LLC
- Inventors: Liang Zhao; Xin Zhao; Shan Liu
- Web page: https://patentgrep.com/patent/US12120335B2

## CPC

- H04N 19/44: Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
- H04N 19/105: Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
- H04N 19/11: among a plurality of spatial predictive coding modes
- H04N 19/159: Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
- H04N 19/176: the region being a block, e.g. a macroblock
- H04N 19/593: involving spatial prediction techniques
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

Methods, apparatus, and computer readable storage medium for intra prediction mode coding in video decoding. The method includes receiving a coded video bitstream; constructing a list of intra modes for a block in the coded video bitstream according to a pre-defined rule based on a size of the block; dividing the list of intra modes into a plurality of intra mode sets for the block; extracting, from the coded video bitstream, a set index indicating an intra mode set from the plurality of intra mode sets; extracting, from the coded video bitstream, a mode index indicating an intra prediction mode from the intra mode set; determining the intra prediction mode for the block based on the set index and the mode index; and decoding the coded video bitstream based on the intra prediction mode.

## Claims

### Claim 1

A method for intra prediction mode coding in video decoding, the method comprising:
receiving, by a device comprising a memory storing instructions and a processor in communication with the memory, a coded video bitstream;
constructing, by the device, a list of intra modes for a block in the coded video bitstream according to a pre-defined rule based on a size of the block;
dividing, by the device, the list of intra modes into a plurality of intra mode sets for the block;
extracting, by the device from the coded video bitstream, a set index indicating an intra mode set from the plurality of intra mode sets;
extracting, by the device, from the coded video bitstream, a mode index indicating an intra prediction mode from the intra mode set;
determining, by the device, the intra prediction mode for the block based on the set index and the mode index; and
decoding, by the device, the coded video bitstream based on the intra prediction mode, wherein:
when the size of the block is equal to or greater than a first threshold:
the list of intra modes comprises a first sub-list being at a top of the list, and
the first sub-list comprises all non-directional intra prediction modes.

### Claim 2 (depends on 1)

The method according to claim 1, wherein:
the first threshold is 8×8; or
the first threshold is 32 in a number of samples.

### Claim 3 (depends on 1)

The method according to claim 1, wherein:
when a neighboring block uses a directional intra prediction mode and when the size of the block is equal to or greater than the first threshold:
the list of intra modes comprises a second sub-list being next to the first sub-list in the list; and
the second sub-list comprises multiple derived intra prediction modes based on the directional intra prediction mode of the neighboring block.

### Claim 4 (depends on 3)

The method according to claim 3, wherein:
the multiple derived intra prediction modes comprises nine directional intra prediction modes by adding an offset of [0, −1, +1, −2, +2, −3, +3, −4, +4] to the directional intra prediction mode of the neighboring block.

### Claim 5 (depends on 3)

The method according to claim 3, wherein:
the list of intra modes comprises a third sub-list being next to the second sub-list in the list; and
the third sub-list comprises default intra prediction modes.

### Claim 6 (depends on 5)

The method according to claim 5, wherein:
the default intra prediction modes comprises at least one nominal directional intra prediction modes with zero delta angle.

### Claim 7 (depends on 1)

The method according to claim 1, wherein:
when the size of the block is smaller than the first threshold:
the list of intra modes comprises the first sub-list being at a top of the list; and
the first sub-list comprises all non-directional intra prediction modes.

### Claim 8 (depends on 7)

The method according to claim 7, wherein:
the list of intra modes comprises a second sub-list being next to the first sub-list in the list; and
the second sub-list comprises default intra prediction modes.

### Claim 9

A method of intra prediction mode coding in video encoding, the method comprising:
receiving, by a device comprising a memory storing instructions and a processor in communication with the memory, video data;
constructing, by the device, a list of intra modes for a block in the video data according to a pre-defined rule based on a size of the block;
dividing, by the device, the list of intra modes into a plurality of intra mode sets for the block;
determining, by the device, a set index indicating an intra mode set from the plurality of intra mode sets;
encoding, by the device, the set index into a coded video bitstream;
determining, by the device, a mode index indicating an intra prediction mode from the intra mode set;
encoding, by the device, the mode index into the coded video bitstream;
determining, by the device, the intra prediction mode for the block based on the set index and the mode index; and
encoding, by the device, the block into the coded video bitstream based on the intra prediction mode,
wherein:
when the size of the block is equal to or greater than a first threshold:
the list of intra modes comprises a first sub-list being at a top of the list, and
the first sub-list comprises all non-directional intra prediction modes.

### Claim 10 (depends on 9)

The method according to claim 9, wherein:
the first threshold is 8×8; or
the first threshold is 32 in a number of samples.

### Claim 11 (depends on 9)

The method according to claim 9, wherein:
when a neighboring block uses a directional intra prediction mode and when the size of the block is equal to or greater than the first threshold:
the list of intra modes comprises a second sub-list being next to the first sub-list in the list; and
the second sub-list comprises multiple derived intra prediction modes based on the directional intra prediction mode of the neighboring block.

### Claim 12 (depends on 11)

The method according to claim 11, wherein:
the multiple derived intra prediction modes comprises nine directional intra prediction modes by adding an offset of [0, −1, +1, −2, +2, −3, +3, −4, +4] to the directional intra prediction mode of the neighboring block.

### Claim 13 (depends on 11)

The method according to claim 11, wherein:
the list of intra modes comprises a third sub-list being next to the second sub-list in the list; and
the third sub-list comprises default intra prediction modes.

### Claim 14 (depends on 13)

The method according to claim 13, wherein:
the default intra prediction modes comprises at least one nominal directional intra prediction modes with zero delta angle.

### Claim 15 (depends on 9)

The method according to claim 9, wherein:
when the size of the block is smaller than the first threshold:
the list of intra modes comprises the first sub-list being at a top of the list; and
the first sub-list comprises all non-directional intra prediction modes.

### Claim 16 (depends on 15)

The method according to claim 15, wherein:
the list of intra modes comprises a second sub-list being next to the first sub-list in the list; and
the second sub-list comprises default intra prediction modes.

### Claim 17

A method of processing video data, the method comprising:
performing, by a device comprising a memory storing instructions and a processor in communication with the memory, a conversion between video data and a bitstream by:
constructing, by the device, a list of intra modes for a block in the video data according to a pre-defined rule based on a size of the block;
dividing, by the device, the list of intra modes into a plurality of intra mode sets for the block;
determining, by the device, a set index indicating an intra mode set from the plurality of intra mode sets;
encoding, by the device, the set index into the bitstream;
determining, by the device, a mode index indicating an intra prediction mode from the intra mode set;
encoding, by the device, the mode index into the bitstream;
determining, by the device, the intra prediction mode for the block based on the set index and the mode index; and
encoding, by the device, the block into the bitstream based on the intra prediction mode,
wherein:
when the size of the block is equal to or greater than a first threshold:
the list of intra modes comprises a first sub-list being at a top of the list, and
the first sub-list comprises all non-directional intra prediction modes.

### Claim 18 (depends on 17)

The method according to claim 17, wherein:
the first threshold is 8×8; or
the first threshold is 32 in a number of samples.

### Claim 19 (depends on 17)

The method according to claim 17, wherein:
when a neighboring block uses a directional intra prediction mode and when the size of the block is equal to or greater than the first threshold:
the list of intra modes comprises a second sub-list being next to the first sub-list in the list; and
the second sub-list comprises multiple derived intra prediction modes based on the directional intra prediction mode of the neighboring block.

### Claim 20 (depends on 19)

The method according to claim 19, wherein:
the multiple derived intra prediction modes comprises nine directional intra prediction modes by adding an offset of [0, −1, +1, −2, +2, −3, +3, −4, +4] to the directional intra prediction mode of the neighboring block.