Support forced subtitles from Dash manifest

[laruedavid]

Use case description

Video can have a "forced" subtitle track used, for example, when characters speak a different language from the main language.
Dash manifests support this feature using a role as mentioned in Amd. 5 for 23009-1: Dash-Industry-Forum/DASH-IF-IOP#165
ExoPlayer already manage forced subtitle with HLS.

Proposed solution

ExoPlayer should parse the "forced_subtitle" role from DASH manifest. If no other subtitle tracks are selected it should show the forced subtitle corresponding to the audio language.

[icbaker]

Thanks for the request - would you be able to provide a sample stream containing the forced_subtitle role that we can use for testing?

[laruedavid]

Hi, thanks for your response. Unfortunately I'm not able to provide a sample stream for now.
Have you possibility to do differently or is it blocking for the feature ?

[icbaker]

We can add the support without a test stream.

[laruedavid]

Do you have any idea of when this feature could be added ?