> Project leaders from Ffmpeg, Google, Mozilla, Microsoft (and probably Nvidia and AMD) need to all get together and decide on a single method.
Speaking non-officially as a browser implementer, VUI isn't always reliable as a source of color, both because the encoders don't always know, and the decoders don't always extract it reliably. The container is a more reliable place to put it (eg. MP4 'colr' box).
Browsers do differ in behavior when these sources of metadata differ. It currently looks likely that WebCodecs will require implementations to use app-provided color metadata over in-band metadata, which would be good for interoperability!
Speaking non-officially as a browser implementer, VUI isn't always reliable as a source of color, both because the encoders don't always know, and the decoders don't always extract it reliably. The container is a more reliable place to put it (eg. MP4 'colr' box).
Browsers do differ in behavior when these sources of metadata differ. It currently looks likely that WebCodecs will require implementations to use app-provided color metadata over in-band metadata, which would be good for interoperability!