Hls.js: Switching subtitle track through hls.js api (question)

[dan-ziv]

Hi, I saw that hls.js provides getter and setter for subtitleTrack.
I was trying to use it to switch subtitles via the hls.js api to avoid doing it via the html5 video api.
Is it supposed to work at all?

Environment

• [x] The stream has correct Access-Control-Allow-Origin headers (CORS)
• [x] There are no network errors such as 404s in the browser console when trying to play the stream
• [x] The issue observed is not already reported by searching on Github under https://github.com/video-dev/hls.js/issues
• [x] The issue occurs in the latest reference client on http://video-dev.github.io/hls.js/demo and not just on my page
• Link to playable M3U8 file: http://cdnbakmi.kaltura.com/p/243342/sp/24334200/playManifest/entryId/0_uka1msg4/flavorIds/1_vqhfu6uy,1_80sohj7p/format/applehttp/protocol/http/a.m3u8
• Hls.js version: 0.7.9
• Browser name/version: Chrome
• OS name/version: MacOS

Steps to reproduce

Play the stream:
http://cdnbakmi.kaltura.com/p/243342/sp/24334200/playManifest/entryId/0_uka1msg4/flavorIds/1_vqhfu6uy,1_80sohj7p/format/applehttp/protocol/http/a.m3u8

Hls provides in his MANFIEST_LOADED event few subtitles tracks.
Try switch subtitles via the api:
hls.subtitleTrack = ;

Expected behavior

1. hls.subtitleTrack has been updated with the new id.
2. Subtitles has been switch successfully on the video.

Actual behavior

1. hls.subtitleTrack has been updated with the new id.
2. Subtitles stays has they were before.

[johnBartos]

I can confirm this. After using the setter, the video tag's text tracks objects aren't updated to switch the active track to showing.

Marking this as a bug for now but I'm not quite certain this feature was ever implemented. As far as I understand the native player's CC button does the job of manipulating the mode of each track (which lets them display or not); Hls.js just listens for these changes and updates it's internal state accordingly. I don't see anything in our codebase which actually sets this mode. In JWPlayer we manage this stuff ourselves.

[dan-ziv]

@johnBartos you are right that the native CC button already does the job of manipulating the mode of each track, but in my case I don't want to use the native html controls for video tag, but to use my own custom UI. In that case, I was think it just reasonable that hls.js will wrap me this implementation with his own api (I just observe that setter and thought this is his purpose).

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[rkalpakova]

I am having the same issue. I need to get the subtitle track to play by default.
I also observed manually setting the subtitle track doesn't flip the mode.