Signaling of slice types in video pictures headers

An apparatus for processing video data comprising a processor and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to:

• determine, for a conversion between a first video picture of a video comprising one or more video pictures and a bitstream of the video, a value of a first syntax element included in a picture header for the first video picture, wherein the first syntax element indicates whether all slices included in the first video picture are I slices;
• determine, based on the value of the first syntax element, whether to signal a second syntax element in a slice header of a slice included in the first video picture, wherein the second syntax element indicates a slice type of the slice;
• and
• perform the conversion based on the determining,
• wherein, in response to the value of the first syntax element indicating that all slices included in the first video picture are I slices, the second syntax element is omitted from slice headers of all slices included in the first video picture, and a value of the second syntax element is inferred to indicate an I slice,
• wherein, in response to the value of the first syntax element indicating that all slices included in the first video picture are I slices, one or more syntax elements are omitted from the picture header for the first video picture in the bitstream,
• wherein the one or more syntax elements comprise a third syntax element specifying usage of a first prediction mode for the first video picture,
• wherein, in the first prediction mode, a signaled motion vector is refined based on at least one motion vector with an offset to the signaled motion vector, and
• wherein the one or more syntax elements are conditionally included in the picture header when the value of the first syntax element does not indicate all slices included in the first video picture are I slices.

A non-transitory computer-readable storage medium storing instructions that cause a processor to:

• determine, for a conversion between a first video picture of a video comprising one or more video pictures and a bitstream of the video, a value of a first syntax element included in a picture header for the first video picture, wherein the first syntax element indicates whether all slices included in the first video picture are I slices;
• determine, based on the value of the first syntax element, whether to signal a second syntax element in a slice header of a slice included in the first video picture, wherein the second syntax element indicates slice type of the slice;
• and
• perform the conversion based on the determining,
• wherein, in response to the value of the first syntax element indicating that all slices included in the first video picture are I slices, the second syntax element is omitted from slice headers of all slices included in the first video picture, and a value of the second syntax element is inferred to indicate I slice,
• wherein, in response to the value of the first syntax element indicating that all slices included in the first video picture are I slices, one or more syntax elements are omitted from the picture header for the first video picture in the bitstream,
• wherein the one or more syntax elements comprise a third syntax element specifying usage of a first prediction mode for the first video picture,
• wherein, in the first prediction mode, a signaled motion vector is refined based on at least one motion vector with an offset to the signaled motion vector, and
• wherein the one or more syntax elements are conditionally included in the picture header when the value of the first syntax element does not indicate all slices included in the first video picture are I slices.

A non-transitory computer-readable storage medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises:

• determine, for a first video picture of a video comprising one or more video pictures, a value of a first syntax element included in a picture header for the first video picture, wherein the first syntax element indicates whether all slices included in the first video picture are I slices;
• determine, based on the value of the first syntax element, whether to signal a second syntax element in a slice header of a slice included in the first video picture, wherein the second syntax element indicates a slice type of the slice;
• and
• generating the bitstream based on the determining,
• wherein, in response to the value of the first syntax element indicating that all slices included in the first video picture are I slices, the second syntax element is omitted from slice headers of all slices included in the first video picture, and a value of the second syntax element is inferred to indicate an I slice,
• wherein, in response to the value of the first syntax element indicating that all slices included in the first video picture are I slices, one or more syntax elements are omitted from the picture header for the first video picture in the bitstream,
• wherein the one or more syntax elements comprise a third syntax element specifying usage of a first prediction mode for the first video picture,
• wherein, in the first prediction mode, a signaled motion vector is refined based on at least one motion vector with an offset to the signaled motion vector, and
• wherein the one or more syntax elements are conditionally included in the picture header when the value of the first syntax element does not indicate all slices included in the first video picture are I slices.