JVET-AP0215 AHG9: On detection of SEI message extensions in SPO [T. M. Borges, Y. Sanchez, R. Skupin, C. Hellge, T. Schierl (HHI)]

SPO includes provisions for the fact that a decoder system may not be able to understand certain SEI messages, e.g. by indicating payload types and prefix bits in the SPO SEI message. However, no dedicated provision in SPO allows decoder systems to recognize presence of SEI message extensions in an efficient way.

This document proposes an extension for the SPO SEI message to add provisions allowing decoder systems to recognize the presence of required SEI message extensions bits in the SEI messages of the indicated processing chains during processing of the SPO SEI message.

The proposal adds a loop over the indicated SEI message types in the SPO SEI message extension to transmit a flag (po_sei_ext_indespensable_flag[ i ]) that indicates whether an SEI message type contains an SEI message payload extension that is required to correctly process the SEI message.

Is related to JVET-AP0216.

Further discussion requested.

Further discussed at 1645 on Wednesday 29 April 2026 chaired by J. Boyce.

A scenario has been described about v6 bitstream handling by a v5 decoder.

This is related to general extensibility in JVET-AP0216. It is requested to study the use cases where the current syntax can not address that requires the message to be the SPO chain.

Further study.

Encoder optimization information (EOI) SEI message (9)

Contributions in this area were discussed during 1725–1930 on Sunday 26 April 2026 and during 1520-1630 on Tuesday 28 April 2026 (chaired by J. Boyce).