Method and apparatus of the quantization matrix computation and representation for video coding

1. A method of video coding, the method comprising:

receiving input data related to a current block in a current picture, wherein the input data correspond to a transform block of the current block at a video encoder side and the input data correspond to a decoded-quantized transform block of the current block at a video decoder side, and wherein a maximum side of the transform block of the current block corresponds to 64;

deriving a scaling matrix from elements of an 8×8 base scaling matrix, wherein when zero out is applied, signaling of the elements in a bottom-right 4×4 region of the 8×8 base scaling matrix is skipped; and

applying a quantization process to the input data according to the scaling matrix to generate a coded-quantized transform block at the video encoder side or applying an inverse quantization process to the input data according to the scaling matrix to generate a decoded transform block at the video decoder side.

2. The method of claim 1 , wherein when the coded-quantized transform block at the video encoder side or the decoded transform block at the video decoder side is 64×64 in size, the transform block has 32×32 non-zero value elements.

3. The method of claim 1 , wherein when the coded-quantized transform block at the video encoder side or the decoded transform block at the video decoder side is 64×N or N×64 in size, the transform block has 32×N or N×32 non-zero value elements, and wherein N is an integer smaller than 64.

4. An apparatus of video coding, the apparatus comprising one or more electronic circuits or processors arranged to:

receive input data related to a current block in a current picture, wherein the input data correspond to a transform block of the current block at a video encoder side and the input data correspond to a decoded-quantized transform block of the current block at a video decoder side, and wherein a maximum side of the transform block of the current block corresponds to 64;

derive a scaling matrix from elements of an 8×8 base scaling matrix, wherein when zero out is applied, signaling of the elements in a bottom-right 4×4 region of the 8×8 base scaling matrix arc is skipped; and

apply a quantization process to the input data according to the scaling matrix to generate a coded-quantized transform block at the video encoder side or apply an inverse quantization process to the input data according to the scaling matrix to generate a decoded transform block at the video decoder side.

5. A method of video coding, the method comprising:

receiving input data related to a current block belonging to a current picture in a first color format that has only a first color component, wherein the input data corresponds to a transform block of the current block at a video encoder side and the input data corresponds to a decoded-quantized transform block of the current block at a video decoder side, and wherein the current block corresponds to the first color component associated with the first color format;

signaling a first scaling matrix at the video encoder side or parsing the first scaling matrix at the video decoder side for the first color component of the current block;

disabling signaling any second scaling matrix at the video encoder side or disabling parsing any second scaling matrix at the video decoder side for a second or third color component that is absent from the current block; and

applying a quantization process to the input data according to the first scaling matrix to generate a coded-quantized transform block at the video encoder side or applying an inverse quantization process to the input data according to the first scaling matrix to generate a decoded transform block at the video decoder side.

6. The method of claim 5 , wherein a flag is signaled in a bitstream to indicate whether said signaling any second scaling matrix at the video encoder side or said parsing any second scaling matrix at the video decoder side for the second or third color component is enabled or disabled.

7. The method of claim 6 , wherein the flag is signaled in an Adaptation Parameter Set (APS) of the bitstream, and wherein the APS has a type corresponding to scaling list data.

8. The method of claim 5 , wherein when one second scaling matrix is not signaled at the video encoder side or not parsed at the video decoder side, a pre-defined second scaling matrix is inferred.

9. The method of claim 8 , wherein whether the pre-defined second scaling matrix is inferred is determined according to syntax elements scaling_list_copy_mode_flag and scaling_list_pred_id_delta.

10. The method of claim 9 , wherein values of the syntax elements scaling_list_copy_mode_flag and scaling_list_pred_id_delta are inferred at the video decoder side if the values of the syntax elements scaling_list_copy_mode_flag and the scaling_list_pred_id_delta are not received.

11. The method of claim 5 , wherein the first color format is a 4:0:0 color format, and the first color component is luma component.

12. The method of claim 5 , wherein the first scaling matrix is referenced by another dependent video layer in a 4:0:0 color format.

13. The method of claim 5 , wherein whether the current picture is in a 4:0:0 color format is indicated by a color format index associated with the current picture.

14. The method of claim 5 , wherein the second or third color component comprises a chroma component.

15. An apparatus of video coding, the apparatus comprising one or more electronic circuits or processors arranged to:

receive input data related to a current block belonging to a current picture in a first color format that has only a first color component, wherein the input data corresponds to a transform block of the current block at a video encoder side and the input data corresponds to a decoded-quantized transform block of the current block at a video decoder side, and wherein the current block corresponds to the first color component associated with the first color format;

signal a first scaling matrix at the video encoder side or parsing the first scaling matrix at the video decoder side for the first color component of the current block;

disable signaling any second scaling matrix at the video encoder side or disabling parsing any second scaling matrix at the video decoder side for a second or third color component that is absent from the current block; and

apply a quantization process to the input data according to the first scaling matrix to generate a coded-quantized transform block at the video encoder side or applying an inverse quantization process to the input data according to the first scaling matrix to generate a decoded transform block at the video decoder side.