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US 2026/0313090 A1Published application
Video coding using cross-component linear model
AssigneeBeijing Dajia Internet Information Technology Co., Ltd.
InventorsYi-Wen CHEN, Xianglin WANG, Xiaoyu XIU
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Abstract
A method, a computing device, and a computer readable storage medium are provided for video coding. The method may include deriving parameter α and parameter β for a CCLM mode by using a predetermined number of neighboring reconstructed luma samples and chroma samples in a CU; and generating a final chroma predictor for the chroma samples of the CU by using the parameter α and the parameter β.
Claims19
A method for video coding, comprising:
- deriving a first parameter α and a second parameter β for a cross-component linear model (CCLM) mode by using four neighboring down-sampled luma samples and four corresponding chroma samples of a coding unit (CU);
- wherein deriving the first parameter α and the second parameter β by using the four neighboring down-sampled luma samples and the four corresponding chroma samples comprises:
- obtaining the first parameter α and the second parameter β by using a weighted average luma value xA of two smaller luma samples xA0, xA1 from the four neighboring down-sampled luma samples, a weighted average luma value xB of two larger luma samples xB0, xB1 from the four neighboring down-sampled luma samples, a weighted average chroma value yA of two chroma samples yA0, yA1 corresponding to the two smaller luma samples, and a weighted average chroma value yB of two chroma samples yB0, yB1 corresponding to the two larger luma samples,
- wherein xA, xB, yA, and yB are obtained by using following equations:
- x
- A
- =
- (
- w
-
- 1
- *
- x
- A
-
- 0
- +
- w
-
- 2
- *
- x
- A
-
- 1
- +
- offset
-
- 1
- )
- ≫
- N
-
- 1
- ;
- x
- B
- =
- (
- w
-
- 3
- *
- x
- B
-
- 0
- +
- w
-
- 4
- *
- x
- B
-
- 1
- +
- offset
-
- 2
- )
- ≫
- N
-
- 2
- ;
- y
- A
- =
- (
- w
-
- 1
- *
- y
- A
-
- 0
- +
- w
-
- 2
- *
- y
- A
-
- 1
- +
- offset
-
- 1
- )
- ≫
- N
-
- 1
- ;
- y
- B
- =
- (
- w
-
- 3
- *
- y
- B
-
- 0
- +
- w
-
- 4
- *
- y
- B
-
- 1
- +
- offset
-
- 2
- )
- ≫
- N
-
- 2
- ;
- wherein w1+w2=(1<<N1), offset1=1<<(N1−1), w3+w4=(1<<N2), offset2=1<<(N2−1),
- wherein w1 is a first weight factor, w2 is a second weight factor, w3 is a third weight factor, w4 is a fourth weight factor, N1 is a first shift value, N2 is a second shift value, offset1 is a first offset factor, and offset2 is a second offset factor;
- and
- generating a predicted chroma sample of the CU by using the first parameter α and the second parameter β.
129 more elements
A computing device, comprising:
- at least one processor;
- 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 processor, cause the computing device to perform acts comprising:
- deriving a first parameter α and a second parameter β for a cross-component linear model (CCLM) mode by using four neighboring down-sampled luma samples and four corresponding chroma samples of a coding unit (CU);
- wherein deriving the first parameter α and the second parameter β by using the four neighboring down-sampled luma samples and the four corresponding chroma samples comprises:
- obtaining the first parameter α and the second parameter β by using a weighted average luma value xA of two smaller luma samples xA0, xA1 from the four neighboring down-sampled luma samples, a weighted average luma value xB of two larger luma samples xB0, xB1 from the four neighboring down-sampled luma samples, a weighted average chroma value yA of two chroma samples yA0, yA1 corresponding to the two smaller luma samples, and a weighted average chroma value yB of two chroma samples yB0, yB1 corresponding to the two larger luma samples,
- wherein xA, xB, yA, and yB are obtained by using following equations:
- x
- A
- =
- (
- w
-
- 1
- *
- x
- A
-
- 0
- +
- w
-
- 2
- *
- x
- A
-
- 1
- +
- offset
-
- 1
- )
- ≫
- N
-
- 1
- ;
- x
- B
- =
- (
- w
-
- 3
- *
- x
- B
-
- 0
- +
- w
-
- 4
- *
- x
- B
-
- 1
- +
- offset
-
- 2
- )
- ≫
- N
-
- 2
- ;
- y
- A
- =
- (
- w
-
- 1
- *
- y
- A
-
- 0
- +
- w
-
- 2
- *
- y
- A
-
- 1
- +
- offset
-
- 1
- )
- ≫
- N
-
- 1
- ;
- y
- B
- =
- (
- w
-
- 3
- *
- y
- B
-
- 0
- +
- w
-
- 4
- *
- y
- B
-
- 1
- +
- offset
-
- 2
- )
- ≫
- N
-
- 2
- ;
- wherein w1+w2=(1<<N1), offset1=1<<(N1−1), w3+w4=(1<<N2), offset2=1<<(N2−1),
- wherein w1 is a first weight factor, w2 is a second weight factor, w3 is a third weight factor, w4 is a fourth weight factor, N1 is a first shift value, N2 is a second shift value, offset1 is a first offset factor, and offset2 is a second offset factor;
- and
- generating a predicted chroma sample of the CU by using the first parameter α and the second parameter β.
133 more elements
A non-transitory computer readable storage medium storing a bitstream generated by performing a method for video coding comprising:
- deriving a first parameter α and a second parameter β for a cross-component linear model (CCLM) mode by using four neighboring down-sampled luma samples and four corresponding chroma samples of a coding unit (CU);
- wherein deriving the first parameter α and the second parameter β by using the four neighboring down-sampled luma samples and the four corresponding chroma samples comprises:
- obtaining the first parameter α and the second parameter β by using a weighted average luma value xA of two smaller luma samples xA0, xA1 from the four neighboring down-sampled luma samples, a weighted average luma value xB of two larger luma samples xB0, xB1 from the four neighboring down-sampled luma samples, a weighted average chroma value yA of two chroma samples yA0, yA1 corresponding to the two smaller luma samples, and a weighted average chroma value yB of two chroma samples yB0, yB1 corresponding to the two larger luma samples,
- wherein xA, xB, yA, and yB are obtained by using following equations:
- x
- A
- =
- (
- w
-
- 1
- *
- x
- A
-
- 0
- +
- w
-
- 2
- *
- x
- A
-
- 1
- +
- offset
-
- 1
- )
- ≫
- N
-
- 1
- ;
- x
- B
- =
- (
- w
-
- 3
- *
- x
- B
-
- 0
- +
- w
-
- 4
- *
- x
- B
-
- 1
- +
- offset
-
- 2
- )
- ≫
- N
-
- 2
- ;
- y
- A
- =
- (
- w
-
- 1
- *
- y
- A
-
- 0
- +
- w
-
- 2
- *
- y
- A
-
- 1
- +
- offset
-
- 1
- )
- ≫
- N
-
- 1
- ;
- y
- B
- =
- (
- w
-
- 3
- *
- y
- B
-
- 0
- +
- w
-
- 4
- *
- y
- B
-
- 1
- +
- offset
-
- 2
- )
- ≫
- N
-
- 2
- ;
- wherein w1+w2=(1<<N1), offset1=1<<(N1−1), w3+w4=(1<<N2), offset2=1<<(N2−1),
- wherein w1 is a first weight factor, w2 is a second weight factor, w3 is a third weight factor, w4 is a fourth weight factor, N1 is a first shift value, N2 is a second shift value, offset1 is a first offset factor, and offset2 is a second offset factor;
- and
- generating a predicted chroma sample of the CU by using the first parameter α and the second parameter β.
129 more elements
Dependencies are inferred from the claim text.