20. The computer system of claim 17 , wherein the different syntax structure includes a next slice segment address that indicates a slice segment address for a next slice segment header when the slice segment address for the next slice segment header is present in the elementary bitstream.
17. A computer system comprising one or more processors, memory, and storage, the memory and/or storage having stored therein computer-executable instructions for causing the computer system, when programmed thereby, to perform operations comprising: detecting completion of a coded region for a region of an image or video; and outputting, in an elementary bitstream, one or more syntax structures that contain the coded region, and, after the one or more syntax structures that contain the coded region, a different syntax structure that indicates the completion of the coded region, wherein the different syntax structure is a supplemental enhancement information (“SEI”) message having a payload type that designates the SEI message as an end-of-region indicator.