Abstract: Methods and apparatus for video bitstream processing are described. The processing may include encoding, decoding or transcoding of digital video. One example method of video bitstream processing includes parsing, for decoding a video picture comprising one or more subpictures, a syntax structure to obtain type information about one or more network abstraction layer (NAL) units making up the video picture and whether the video picture is an intra random access picture (IRAP) and reconstructing the one or more subpictures based on the parsing.

Abstract: Methods, apparatus and systems for video bitstream generation and parsing are described. One example bitstream decoding method includes parsing a portion of a video bitstream at a video unit level for a first field indicative of whether a slice height is specified for a subpicture partitioning or for a tile partitioning at the video unit level, parsing, due to determining that the first field indicates that the slice height is specified for the subpicture partitioning, N second fields in the portion of the video bitstream to obtain heights for rectangular slices in the video unit, wherein the heights are indicated in multiple of coding tree unit (CTU) heights, and wherein each rectangular slice comprises one or more CTU rows that belong to a same subpicture, wherein N is a positive integer, and decoding, based on the first field and/or the N second fields, the video bitstream to generate a video.

Abstract: Methods, apparatus and systems for video bitstream generation and parsing are described. One example method of video bitstream processing includes parsing a header at a video unit level in a video bitstream for a first field indicative of whether the video unit includes multiple network abstraction layer bit units having multiple types, parsing, due to determining that the video unit includes multiple network abstraction layer bit units having multiple types, a second field in the header indicative of whether the video unit comprises an intra random access point, and decoding, based on the first field and the second field, the video bitstream to generate a video.