idea: discontinuities with extra decoder config on the packet.
Also, why not just have the packet metadata on the packet? I think that would make things easier overall.

- keep input/demuxer.isSupported()?
- getCodecParamterString() hack feels dirty; idk. well its not really a hack but, surface it over a different field?

- Add an HLS "live mode". Challenge, where does bitrate come from?

- fmp4 muxing (CMAF??)
- ext-x-i-frames-only writing