Get regular playlist url properly in ha-hls-player#7417
Get regular playlist url properly in ha-hls-player#7417bramkragten merged 6 commits intohome-assistant:devfrom
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@hunterjm How about just doing this? It will skip one extra load if possible, and it will fall back to the master playlist if it doesn't match. The only potential concern is it would only grab the first stream of an adaptive master playlist (or a playlist with separated tracks), but I don't think we will be using those. Actually, if that is a concern we could easily test for those too as those would have more matches to the regexp. |
src/components/ha-hls-player.ts
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| const playlistRegexp = /#EXT-X-STREAM-INF:.*?(?:CODECS=".*?(hev1|hvc1)?\..*?".*?)?(?:\n|\r\n)(.+)/g; | ||
| const match = playlistRegexp.exec(masterPlaylist); | ||
| if (match !== null && playlistRegexp.exec(masterPlaylist) === null) { | ||
| playlist_url = new URL(match[2], this.url).href; |
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Please explain to me, and in a comment in the code, what we are doing here.
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Sure, I added comments to the code which should help clarify things.
HLS has two types of playlists, a master playlist and regular playlists. The master playlist usually contains multiple variant streams and metadata which describes them (including bandwidth and resolution). The players can then choose between the variants depending on available resources.
The stream component originally just used a single regular playlist since we only have one stream variant. In 0.115, we made several changes to stream, including not including an audio stream with the video stream when there is no audio. However, this made chromecast devices not play the stream. We realized that we could fix around this problem by making a master playlist with only our single variant regular playlist with metadata which indicated that the stream had only video and no audio.
After this change, the stream component now sends a master playlist instead of a regular playlist. This is slightly less efficient since a master playlist must be loaded and parsed before the regular playlist can be loaded and played. Using a master playlist did help us by giving the ability to check the codec of the stream so we could restrict ExoPlayer use to only videos using the H.265 (HEVC) codec. But this actually resulted in 2 loads of the master playlist before the regular playlist load - once by ha-hls-player to check the codec, then once by the player itself. So we effectively went from one load (the player loading the regular playlist) to three loads (ha-hls-player loading the master playlist, the player loading the master playlist, then the player loading the regular playlist).
We previously reduced these 3 loads to 2 loads by passing the regular playlist directly to the player, helping the player avoid loading the master playlist. However, we did this by a simple string replace. @hunterjm noted that this might be undesirable because makes the frontend rely on the path of the variant stream coded in the backend.
This PR just gets the regular playlist correctly by parsing the regular playlist url from the master playlist.
src/components/ha-hls-player.ts
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| // Get the regular playlist url from the input (master) playlist, falling back to the input playlist if necessary | ||
| // This avoids the player having to load and parse the master playlist again before loading the regular playlist | ||
| let playlist_url: string; | ||
| if (match !== null && playlistRegexp.exec(masterPlaylist) === null) { |
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It still is not clear what we are doing here, why do we do the regex a second time and why should it not match?
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The second regex is to test whether there's another #EXT-X-STREAM-INF line which would mean that our master playlist has more than one stream. We should actually not encounter this case currently as we are currently only include one stream in our master playlist, but in case we change things, this safely sends the master_playlist instead of skipping to the regular playlist when there is more than one stream available.
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Please add comment for that, can we also give the various match part logical variable names? like:
const isHevc = match && match[1];
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I pushed a change, does that look better? I haven't had a chance to test it yet
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Yes, that looks better. Let me know when you tested it :-)
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Just tested it and seems to be working fine
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Proposed change
The existing way of getting the regular playlist from the master playlist used a simple string replace. This couples the frontend to the naming convention of the playlists in the backend. This PR gets the regular playlist url properly by parsing the url from the master playlist.
Type of change
Example configuration
Additional information
Checklist
If user exposed functionality or configuration variables are added/changed: