
The `MediaMuxer` (FrameworkMuxer) supports AV1 mime type from API 34. For this to work track `Format/MediaFormat` must have `CSD` data. Change also include providing AV1 option in demo app. Transmuxing of an AV1 mime type input will not work because `Extractor` does not extract AV1 CSD data. Verified changes manually via demo app. PiperOrigin-RevId: 603002380