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US 10,855,997 B2Granted
Secondary transform kernel size selection
AssigneeMediatek Inc.
InventorsMan-Shu Chiang, Chih-Wei Hsu, Tzu Der Chuang, Ching-Yeh Chen
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Abstract
A method and apparatus related to secondary transform operations. In which, the non-zero transform coefficients in a particular subset of the transform coefficients of the block of pixels is counted and compared with a particular threshold so as to determine whether or not to perform the secondary transform on the block of pixels. Besides, the optimal secondary transform kernel size is derived implicitly based on the size of the block, or derived explicitly based on a flag coded by using an adaptive code word.
Claims20
A video decoding method comprising:
- receiving data associated with a block of pixels to be decoded as a current block of a current picture of video;
- applying inverse non-separable secondary transform (NSST) to transformed coefficients of the block of pixels according to an NSST kernel size selected from a plurality of possible kernel sizes when determining a count of non-zero transformed coefficients in a particular subset of the transformed coefficients of the block of pixels is greater than a first threshold;
- and
- decoding using the selected NSST kernel size that is derived according to a width of the block or a height of the block,
- wherein the applying of the inverse NSST comprises:
- applying inverse 4×4 NSST to first 8 or 16 coefficients for a transform block based on the width or the height of the block being less than a second threshold;
- or
- applying inverse 8×8 NSST to first 8 or 16 coefficients for a transform block based on the width and the height of the block being greater than or equal to the second threshold,
- wherein the inverse 4×4 NSST and the inverse 8×8 NSST indicate different kernel sizes and the particular subset of the transformed coefficients depends on the width of the block or the height of the block.
6 more elements
An electronic apparatus comprising:
- a circuit configured to perform operations comprising:
- receiving data associated with a block of pixels to be decoded as a current block of a current picture of video;
- applying inverse non-separable secondary transform (NSST) to transformed coefficients of the block of pixels according to an NSST kernel size selected from a plurality of possible kernel sizes when determining a count of non-zero transformed coefficients in a particular subset of the transformed coefficients of the block of pixels is greater than a first threshold;
- and
- decoding using the selected NSST kernel size that is derived according to a width of the block or a height of the block, wherein, in applying the inverse NSST, the circuit performs operations comprising:
- applying inverse 4×4 NSST to first 8 or 16 coefficients for a transform block based on the width or the height of the block being less than a second threshold;
- or
- applying inverse 8×8 NSST to first 8 or 16 coefficients for the transform block based on the width and the height of the block being greater than or equal to the second threshold,
- wherein the inverse 4×4 NSST and the inverse 8×8 NSST indicate different kernel sizes and the particular subset of the transformed coefficients depends on the width of the block or the height of the block.
6 more elements
Dependencies are inferred from the claim text.