US 11,388,436 B2Granted

Bit-width control for bi-directional optical flow

AssigneeBeijing Dajia Internet Information Technology Co., Ltd.

InventorsXiaoyu Xiu, Yi-Wen Chen, Xianglin Wang

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Abstract

A method for controlling bit-width for bi-directional optical flow (BDOF) for video coding includes decoding a first reference picture and a second reference picture, the second reference picture being different than the first reference picture, wherein the first reference picture is displayed before a current picture and the second reference picture is displayed after the current picture. A motion refinement of a coding unit (CU) is calculated by minimizing a difference between a first prediction L0 and a second prediction L1. First gradient values for the first prediction Lo and second gradient values for the second prediction L1 are calculated. A final bi-prediction of the CU is calculated. Also disclosed are an associated apparatus and an associated non-transitory computer readable storage medium.

Claims21

Dependent claims

A method for video decoding, comprising:

decoding a first reference picture and a second reference picture, the second reference picture being different than the first reference picture, wherein the first reference picture is displayed before a current picture and the second reference picture is displayed after the current picture;
determining, for a current block of the current picture, a first prediction L0 corresponding to the first reference picture;
determining, for the current block, a second prediction L1 corresponding to the second reference picture;
calculating a respective motion refinement (vx, vy) of each subblock of the current block by minimizing a difference between the first prediction L0 and the second prediction L1 based on a motion refinement threshold and a plurality of internal parameters representing different summation characters of the first prediction L0 and the second prediction L1;
calculating first gradient values
∂
I
(
0
)
∂
x
⁢
(
i
,
j
)
⁢
⁢
and
⁢
⁢
∂
I
(
0
)
∂
y
⁢
(
i
,
j
)
for the first prediction L0 and second gradient values
∂
I
(
1
)
∂
x
⁢
(
i
,
j
)
⁢
⁢
and
⁢
⁢
∂
I
(
1
)
∂
y
⁢
(
i
,
j
)
for the second prediction L1, wherein I(0)(i, j) is a prediction sample at sample location (i, j) of the first prediction L0, and I(1)(i, j) is a prediction sample at the sample location (i, j) of the second prediction L1;
and
calculating a final bi-prediction of the current block based on the first prediction L0, the second prediction L1, respective motion refinements (vx, vy), the first gradient values
∂
I
(
0
)
∂
x
⁢
(
i
,
j
)
⁢
⁢
and
⁢
⁢
∂
I
(
0
)
∂
y
⁢
(
i
,
j
)
,
and the second gradient values
∂
I
(
1
)
∂
x
⁢
(
i
,
j
)
⁢
⁢
and
⁢
⁢
∂
I
(
1
)
∂
y
⁢
(
i
,
j
)
.

133 more elements

A computing device, comprising:

one or more processors;
a non-transitory storage coupled to the one or more processors;
and
a plurality of programs stored in the non-transitory storage that, when executed by the one or more processors, cause the computing device to perform acts comprising:
decoding a first reference picture and a second reference picture, the second reference picture being different than the first reference picture, wherein the first reference picture is displayed before a current picture and the second reference picture is displayed after the current picture;
determining, for a current block of the current picture, a first prediction L0 corresponding to the first reference picture;
determining, for the current block, a second prediction L1 corresponding to the second reference picture;
calculating a respective motion refinement (vx, vy) of each subblock of the current block by minimizing a difference between the first prediction L0 and the second prediction L1 based on a motion refinement threshold and a plurality of internal parameters representing different summation characters of the first prediction L0 and the second prediction L1;
calculating first gradient values
∂
I
(
0
)
∂
x
⁢
(
i
,
j
)
⁢
⁢
and
⁢
⁢
∂
I
(
0
)
∂
y
⁢
(
i
,
j
)
for the first prediction L0 and second gradient values
∂
I
(
1
)
∂
x
⁢
(
i
,
j
)
⁢
⁢
and
⁢
⁢
∂
I
(
1
)
∂
y
⁢
(
i
,
j
)
for the second prediction L1, wherein I(0)(i, j) is a prediction sample at sample location (i, j) of the first prediction L0, and I(1)(i, j) is a prediction sample at the sample location (i, j) of the second prediction L1;
and
calculating a final bi-prediction of the current block based on the first prediction L0, the second prediction L1, respective motion refinements (vx, vy), the first gradient values
∂
I
(
0
)
∂
x
⁢
(
i
,
j
)
⁢
⁢
and
⁢
⁢
∂
I
(
0
)
∂
y
⁢
(
i
,
j
)
,
and the second gradient values
∂
I
(
1
)
∂
x
⁢
(
i
,
j
)
⁢
⁢
and
⁢
⁢
∂
I
(
1
)
∂
y
⁢
(
i
,
j
)
.

137 more elements

Dependencies are inferred from the claim text.

Facts

Application: 17/368,468Filed 6 Jul 2021 · continuation
Priority: 6 Jan 2019
Published: US 2021/0344952 A14 Nov 2021
Granted: 12 Jul 2022
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

H04N 19/105
Selection of coding mode or of prediction mode: selection of the reference unit for prediction within a chosen coding or prediction mode, e.g.…
H04N 19/577
Motion estimation or motion compensation: motion compensation with bidirectional frame interpolation, i.e. using B-pictures
H04N 19/103
Characterised by the element, parameter or selection affected or controlled by the adaptive coding: selection of coding mode or of prediction mode
H04N 19/176
The unit being an image region, e.g. an object: the region being a block, e.g. a macroblock

Family

Application62/788,898Us provisional application · filed 6 Jan 2019
PCT/US2020/012338Parent of this continuation · filed 6 Jan 2020
US 2021/0344952 A1Pre-grant publication · published 4 Nov 2021
US 11,350,123 B2Related patent
US 11,388,436 B2This patent

From the US filing history. Foreign family members aren’t listed.