Data storage in buffers for intra block copy in video coding

Patent metadata

Field	Value
Publication number	US-11228775-B2
Application number	US-202117320008-A
Country	US
Kind code	B2
Filing date	May 13, 2021
Priority date	Feb 2, 2019
Publication date	Jan 18, 2022
Grant date	Jan 18, 2022

Abstract

A method of visual media processing includes determining a size of a buffer to store reference samples for prediction in an intra block copy mode; and performing a conversion between a current video block of visual media data and a bitstream representation of the current video block, using the reference samples stored in the buffer, wherein the conversion is performed in the intra block copy mode which is based on motion information related to a reconstructed block located in same video region with the current video block without referring to a reference picture.

First claim

The invention claimed is:

1. A method of visual media processing, comprising:
determining, for a conversion of a current video block of a video and a bitstream of the video, that a first coding mode is applied on the current video block;
deriving a first block vector (BVx, BVy) for the current video block;
generating, based on the first block vector and a buffer, a first prediction sample for a first sample (x0, y0) in the current video block, wherein a width and a height of the buffer is represented by M and N respectively, and wherein in the first coding mode, prediction samples of the current video block are derived from a same picture including the current video block; and
performing the conversion based on the prediction samples of the current video block;
wherein a location converting operation is applied on (x0+BVx, y0+BVy) to derive a position in the buffer for the first prediction sample,
wherein the location converting operation is a modulus operation, and the position of the first prediction sample is represented by ((x0+BVx) mod M, (y0+BVy) mod N), mod is a modulus function, or
wherein the location converting operation is a clipping operation, and the position of the first prediction sample is represented by ((clip3(leftBry, rightBry, (x0+BVx), (clip3(topBry, botBry, (x0+BVx), (y0+BVy) mod N), and wherein leftBry, rightBry, topBry and botBry is a left boundary, right boundary, top boundary and bottom boundary of the buffer respectively, and clip3 is a clipping operation which is defined as:

Clip
⁢

⁢
3
⁢

(

x
,
y
,
z

)

=

{

x
;

z
<
x

y
;

z
>
y

z
;

otherwise

.

2. The method of claim 1 , wherein the first block vector (BVx, BVy) is based on integer-pixel precision.

3. The method of claim 1 , wherein the buffer is stored with reconstructed samples without applying an in-loop filtering process.

4. The method of claim 1 , wherein the M and N are kept unchanged for the picture including the current video block.

5. The method of claim 1 , wherein the buffer is reset to a fix value for every coding tree unit row.

6. The method of claim 1 , wherein an order of storing reconstructed samples is same as a coding order.

7. The method of claim 1 , wherein the buffer is a rectangular region, and M is great than N.

8. The method of claim 1 , wherein the conversion includes encoding the current video block into the bitstream.

9. The method of claim 1 , wherein the conversion includes decoding the current video block from the bitstream.

10. An apparatus for processing video data comprising a processor and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to:
determine, for a conversion of a current video block of a video and a bitstream of the video, that a first coding mode is applied on the current video block;
derive a first block vector (BVx, BVy) for the current video block;
generate, based on the first block vector and a buffer, a first prediction sample for a first sample (x0, y0) in the current video block, wherein a width and a height of the buffer is represented by M and N respectively, and wherein in the first coding mode, prediction samples of the current video block are derived from a same picture including the current video block; and
perform the conversion based on the prediction samples of the current video block;
wherein a location converting operation is applied on (x0+BVx, y0+BVy) to derive a position of the first prediction sample,
wherein the location converting operation is a modulus operation, and the position of the first prediction sample is represented by ((x0+BVx) mod M, (y0+BVy) mod N), mod is a modulus function, or wherein the location converting operation is a clipping operation, and the position of the first prediction sample is represented by ((clip3(leftBry, rightBry, (x0+BVx), (clip3(topBry, botBry, (x0+BVx), (y0+BVy) mod N), and wherein leftBry, rightBry, topBry and botBry is a left boundary, right boundary, top boundary and bottom boundary of the buffer respectively, and clip3 is a clipping operation which is defined as:

Clip
⁢

⁢
3
⁢

(

x
,
y
,
z

)

=

{

x
;

z
<
x

y
;

z
>
y

z
;

otherwise

.

11. The apparatus of claim 10 , wherein the first block vector (BVx, BVy) is based on integer-pixel precision.

12. The apparatus of claim 10 , wherein the buffer is

Assignees

• Beijing Bytedance Network Tech Co Ltd
• Bytedance Inc

Inventors

• Xu Jizheng
• Zhang Li
• Zhang Kai
• Liu Hongbin
• Wang Yue

Classifications

• H04N19/117

  Filters, e.g. for pre-processing or post-processing (sub-band filter banks H04N19/635) · CPC title

• H04N19/82

  involving filtering within a prediction loop · CPC title

• H04N19/426

  using memory downsizing methods · CPC title

• H04N19/86

  involving reduction of coding artifacts, e.g. of blockiness · CPC title

• H04N19/186

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