HLS MoQ

[mcintyrehh]

Work in progress for #863

This simplifies/cleans up the hls import a bit and allows us to proxy an HLS source to be served from a MoQ backend.

Currently an HLS client can successfully:

• fetch the master playlist, media playlists, and init segments

Requests for segments ('http://localhost:4443/fetch/anon/bbb/video0.m4s?group=284') are timing out. Debugging this now.

Updates:

• Updated web.rs to add a "Content-Type": "application/vnd.apple.mpegurl" header for .m3u8 requests. This lets us plop the master playlist url in safari/chrome directly for super easy testing.
• Removed a bunch of logic around matching video track with audio tracks. All we do now is create a video track for all variants added in the master playlist, and an audio track for all alternatives.
• Creates a new track for each each media playlist
• Creates an "init segment" track with a single group for each media playlist

What is next:

• figure out why segment/group requests are 504ing
• consolidate audio_tracks and video_tracks into media_tracks. lots we can dedupe here, the HLS import really doesn't need to care what the contents of these playlists are, outside of choosing which media importer to use (aac/fmp4)
• get rid of the hardcoding to have a single audio track
• add text track support, this should be super easy

How to test:

• run just relay in one terminal
• run just hls bbb in another
• drop http://localhost:4443/fetch/anon/bbb/playlist.m3u8 into Safari/Chrome
  • or hls.js demo page: https://hlsjs.video-dev.org/demo/?src=http%3A%2F%2Flocalhost%3A4443%2Ffetch%2Fanon%2Fbbb%2Fplaylist.m3u8&demoConfig=eyJlbmFibGVTdHJlYW1pbmciOnRydWUsImF1dG9SZWNvdmVyRXJyb3IiOnRydWUsInN0b3BPblN0YWxsIjpmYWxzZSwiZHVtcGZNUDQiOmZhbHNlLCJsZXZlbENhcHBpbmciOi0xLCJsaW1pdE1ldHJpY3MiOi0xfQ==
  • or video.js demo page: https://videojs-http-streaming.netlify.app/?debug=false&autoplay=false&muted=false&fluid=false&minified=false&sync-workers=false&liveui=true&llhls=true&url=http%3A%2F%2Flocalhost%3A4443%2Ffetch%2Fanon%2Fbbb%2Fplaylist.m3u8&type=application%2Fx-mpegURL&keysystems=&buffer-water=false&exact-manifest-timings=false&pixel-diff-selector=false&network-info=true&dts-offset=false&override-native=true&object-fit=false&use-mms=true&preload=auto&mirror-source=true&forced-subtitles=false&native-text-tracks=false

So close! You can see video.js requesting the playlists and the actual M3u8s look great: