296efbb395
We add an entire class like we do for parsing other codec initialization formats; it's currently not doing any parsing though (... initialization data is really simple for AV1 though: just the entire contents of the box). For testing, we add the sample file, having been re-encoded with ffmpeg (and we also happen to have another av1 file, too). PiperOrigin-RevId: 439453823
Extractor module
Provides media container extractors and related utilities. Application code will not normally need to depend on this module directly.