- Retaining Input instances for segments without clogging up memory indefinitely

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.

- ALL_FORMATS but for HLS only

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