Signaling output picture size for reference picture resampling

1. A method for video decoding performed by at least one processor, the method comprising:

acquiring an input bitstream comprising metadata and video data;

decoding the video data;

determining whether the metadata comprises at least one flag signaling at least one component of a picture size of at least one picture of the video data;

signaling, in a case where it is determined that the metadata comprises the at least one flag, a display device to display the at least one picture from the video data according to the at least one flag;

signaling, in response to determining that the metadata comprises at least one of a width value and a height value, at least one post-resampling process to maintain the at least one of the width value and the height value for display of the at least one picture by the display device; and

determining, in response to determining that the metadata comprises the at least one flag, whether the metadata specifies that any post-resampling process is applied to each of a plurality of cropped output pictures such that each of a plurality of resampled output pictures has a constant picture size by indicating in which at least one of:

the metadata comprises the width value specifying the width with respect to a plurality of pictures, including the at least one picture, and

the metadata comprises the height value specifying the height with respect to the plurality of pictures,

wherein at least one of the value of the component comprises the at least one of the width and the height,

wherein the video data is encoded in a versatile video coding (VVC) format, and

wherein the at least one flag specifies whether to display the at least one picture at the picture size according to a value of the component that is present and indicated by the metadata.

2. The method for video decoding according to claim 1 ,

wherein the component comprises at least one of a width and a height of the at least one picture.

3. The method for video decoding according to claim 2 ,

wherein the at least one of the width and the height of the at least one picture comprises units of luma samples.

4. The method for video decoding according to claim 1 , further comprising:

signaling, in response to determining that the metadata is absent the width value, the at least one post-resampling process to maintain the width value at a value indicated by a sequence parameter set of the video data.

5. The method for video decoding according to claim 1 , further comprising:

signaling, in response to determining that the metadata is absent the height value, the at least one post-resampling process to maintain the height value at a height indicated by a sequence parameter set of the video data.

6. The method for video decoding according to claim 1 ,

wherein the video data comprises the at least one flag as a video usage information (VUI) parameter.

7. An apparatus for video decoding, the apparatus comprising:

at least one memory configured to store computer program code;

at least one processor configured to access the computer program code and operate as instructed by the computer program code, the computer program code including:

acquiring code configured to cause the at least one processor to acquire an input bitstream comprising metadata and video data;

decoding code configured to cause the at least one processor to decode the video data;

determining code configured to cause the at least one processor to determine whether the metadata comprises at least one flag signaling at least one component of a picture size of at least one picture of the video data;

signaling code configured to cause the at least one processor to:

signal, in a case where it is determined that the metadata comprises the at least one flag, a display device to display the at least one picture from the video data according to the at least one flag; and

signal, in in response to determining that the metadata comprises at least one of a width value and a height value, at least one post-resampling process to maintain the at least one of the width value and the height value for display of the at least one picture by the display device; and

further determining code configured to cause the at least one processor to determine, in response to determining that the metadata comprises the at least one flag, whether the metadata specifies that any post-resampling process is applied to each of a plurality of cropped output pictures such that each of a plurality of resampled output pictures has a constant picture size by indicating in which at least one of:

the metadata comprises the width value specifying the width with respect to a plurality of pictures, including the at least one picture, and

the metadata comprises the height value specifying the height with respect to the plurality of pictures,

wherein at least one of the value of the component comprises the at least one of the width and the height,

wherein the video data is encoded in a versatile video coding (VVC) format, and

wherein the at least one flag specifies whether to display the at least one picture at the picture size according to a value of the component that is present and indicated by the metadata.

8. The apparatus for video decoding according to claim 1 ,

wherein the component comprises at least one of a width and a height of the at least one picture.

9. The apparatus for video decoding according to claim 8 ,

wherein the at least one of the width and the height of the at least one picture comprises units of luma samples.

10. The apparatus for video decoding according to claim 7 , wherein the signaling code is further configured to cause the at least one processor to signal, in response to determining that the metadata is absent the width value, the at least one post-resampling process to maintain the width value at a value indicated by a sequence parameter set of the video data.

11. The apparatus for video decoding according to claim 7 , wherein the signaling code is further configured to cause the at least one processor to signal, in response to determining that the metadata is absent the height value, the at least one post-resampling process to maintain the height value at a height indicated by a sequence parameter set of the video data.

12. A non-transitory computer readable medium storing a program configured to cause a computer to:

acquire an input bitstream comprising metadata and video data;

decode the video data;

determine whether the metadata comprises at least one flag signaling at least one component of a picture size of at least one picture of the video data; and

signal, in a case where it is determined that the metadata comprises the at least one flag, a display device to display the at least one picture from the video data according to the at least one flag;

signal, in response to determining that the metadata comprises at least one of a width value and a height value, at least one post-resampling process to maintain the at least one of the width value and the height value for display of the at least one picture by the display device; and

determine, in response to determining that the metadata comprises the at least one flag, whether the metadata specifies that any post-resampling process is applied to each of a plurality of cropped output pictures such that each of a plurality of resampled output pictures has a constant picture size by indicating in which at least one of:

the metadata comprises the width value specifying the width with respect to a plurality of pictures, including the at least one picture, and

the metadata comprises the height value specifying the height with respect to the plurality of pictures,

wherein at least one of the value of the component comprises the at least one of the width and the height,

wherein the video data is encoded in a versatile video coding (VVC) format, and

wherein the at least one flag specifies whether to display the at least one picture at the picture size according to a value of the component that is preset and indicated by the metadata.