SampleAuxiliaryInformationOffsetsBox - allowed versions?

[bradh]

The syntax for the SampleAuxiliaryInformationOffsetsBox in ISO/IEC 14496-12:2022 has options for the size of the offset array that looks like:

if ( version == 0 ) {
    unsigned int(32) offset[ entry_count ];
}
else {
    unsigned int(64) offset[ entry_count ];
}

Is the intention that the version field can be anything? Would it be (technically) valid to write a version of 0xFF and expect that any implementation could correctly parse it, at least at iso6 or higher? Or should the version always be 0x00 or 0x01?

[podborski]

The version should always be 0 or 1 in this case. I raised the same issue some time ago at MPEG. I think we should fix all the syntax to something like:

if ( version == 0 ) {
    unsigned int(32) offset[ entry_count ];
}
else if (version == 1) {
    unsigned int(64) offset[ entry_count ];
}

And make sure that if an unspecified version is used there would be no syntax elements defined.

[cconcolato]

The group agrees to clarify the syntax. We will decide on the best vehicle to make the changes, possibly in the 8th edition. We also look into clearly specifying a "max version" and clarifying which flags are defined. We welcome concrete text in contributions. We also look into the collaboration with the SDL group.