Prepare for Supporting Additional Video Codecs

[softworkz]

This PR is making preparations for the support of additional video codecs in the future.

The individual changes are:

Rename types and variables for generic video codec handling

• Rename interface DemuxedVideoTrack to DemuxedVideoTrackBase
• Rename DemuxedAvcTrack to DemuxedVideoTrack
• Add manifestCodec property to DemuxedVideoTrackBase
• Rename AvcSample to VideoSample
• Rename AvcSampleUnit to VideoSampleUnit
• Rename ParsedAvcSample to ParsedVideoSample
• Rename avcData to videoData
• Rename avcId to videoPid
• Rename audioId to audioPid and id3Id to id3Pid (for clarity)
• Rename segmentCodec to segmentAudioCodec and add segmentVideoCodec

Re-Organization

• Add BaseVideoParser and AvcVideoParser classes and move parseAVCPES and related methods into those classes
• Create subfolders demux/audio and demux/video and move the corresponding modules there

[softworkz]

All comments addressed, thanks again, Rob!

[robwalch]

There are no plans to support additional codecs in MPEG-TS. Other players depend on adavanced codecs being delivered via fmp4. It would be best to maintain cross-compatibility and drive adoption of fmp4 (#4943).

[softworkz]

There are no plans to support additional codecs in MPEG-TS. Other players depend on adavanced codecs being delivered via fmp4. It would be best to maintain cross-compatibility and drive adoption of fmp4 (#4943).

Then, thanks for merging, though. This provides at least room for working on HEVC support without running into rebase trouble on each upstream update.

From our side, adoption of HEVC over fmp4 is a non-option. The primary interest is in re-streaming TV signals where the original mux is just filtered and segmented without remuxing or re-packaging.
Besides that, MPEGTS allows for lower latency than fmp4 (afaik).

Also, beyond those TV streams, we have no intentions for fmp4 adoption either.
This is purely an Apple idea (I don't know why), but not even reflected in the HLS spec (albeit mostly driven by Apple).

Actually, there are two codecs of interest: HEVC and MPEG2 Video. The latter is not supported in Chrome yet and they said they have no plans for supporting it. But they said the same about HEVC even until shortly before it was delivered.. 😆

[softworkz]

adoption of fmp4 (#4943).

The referenced issue shows that there's not much agreement regarding HEVC-over-fmp4 only.