Playlist: HLS (.m3u8) files not playing

[petemill]

Description

Playlist service is assuming all files will be .mp4 (or single file). Many sites provide an m3u8 index which offers conditional chunks based on device characteristics like resolution or network speed. This affects:

• Online playing because the wrong type is provided to the client
• Offline saving because the Playlist service does not know how to download all the chunks

The HLS Playlist format looks like this:

• Multivariant: https://developer.apple.com/documentation/http-live-streaming/creating-a-multivariant-playlist
• Simple: https://developer.apple.com/documentation/http-live-streaming/video-on-demand-playlist-construction

Android stop-gap solution

In order to support m3u8 on android the quickest, we could allow Android to perform its own .m3u8 offline download with local APIs which are available. The android Java would check its own offline state for each media item as well as the Playlist Service's offline state for each media item.

In the future, the Playlist Service may support .m3u8 / HSL offline download and we can change Android to use that at that time.

Supporting offline HLS media downloads in Chromium

To integrate HSL in to the current PlaylistService architecture, we would need to

• Download and parse the parent .m3u8 file
• If the playlist is multivariant, decide which variants are important via choices of codecs, resolution, bitrate, etc.
• Download the chosen variant's .m3u8 file
• Download to disk all files from each required track
• Create a new .m3u8 that only contains our chosen tracks, with URLs to each track segment that makes sense to the URLDataSource that we can provide to a video player element.

Parsing

• We can download and parse via media::hls::Playlist::IdentifyPlaylist which tells us if it's a simple MediaPlaylist, or a MultivariantPlaylist with multiple VariantStream children (each of which point to a MediaPlaylist via Url).
• We can make a decision about which variant we should use, based on codec and bandwidth.
• We can download and parse the variant's m3u8 via MediaPlaylist::Parse.
• We can download each MediaSegment within that Playlist via GetUri + GetByteRange.

Unknowns

• [ ] How to decide which Variant we support (which codec / resolution chromium's video player can play back)
• [ ] Does a separate audio Variant need to be downloaded
• [ ] How to reconstutute the simplified m3u8 file, might need to make custom code for that.

[sangwoo108]

@deeppandya , so online playing wasn't working with wrong extension? I'm really curious why it had worked before.

[deeppandya]

@deeppandya , so online playing wasn't working with wrong extension? I'm really curious why it had worked before.

I have the implementation ready to work with HLS file with online mode.

[sangwoo108]

I have the implementation ready to work with HLS file with online mode.

I mean, you said it worked before, HLS wasn't supported then?

[sangwoo108]

Accidentlay typed "Playlist" to cs.chromium.org and got this

https://source.chromium.org/chromium/chromium/src/+/8b69eb115911bcb85a160c7ae31e4c323535f5eb:media/formats/hls/playlist.h;bpv=1;bpt=0