Hello,
I develop a webOS TV video app (com.gostream.app, currently in QA). Playback uses a plain HTML5 <video> element, and the streams are MKV or TS files that carry several embedded subtitle tracks.
In topic 28519 the answer to a question about luna://com.webos.media was that it is a webOS OSE resource, and that webOS TV apps should use only the webOS TV resources documented on this site.
I accept that. So my question is not about com.webos.media - it is about what replaces it:
What is the supported webOS TV API for a store app to enumerate, select and display the subtitle tracks embedded in the file that an HTML5 <video> element is playing?
Concretely:
(a) Enumeration. On our test TVs video.textTracks stays empty for embedded subtitle tracks, while video.audioTracks is correctly populated with the embedded audio tracks of the same file. Both come from the same demuxer. Is the empty textTracks intended behaviour, or a defect?
(b) Selection. If textTracks is not populated, there is no standard way to switch between, for example, three embedded subtitle languages. Is there a documented webOS TV API for this?
(c) Styling. The TV’s own caption settings (size, colour, position) apply to the built-in player. Is there a supported way for an app to read or apply them to HTML5 video?
(d) If the answer to all three is “there is none”, could you please state that explicitly? Then developers know the only supported route is to demux subtitles off-device and render them in JavaScript. That carries a real cost in extraction, bandwidth and latency, and we would rather build it deliberately than guess.
Why this is time-sensitive. From March 2027 requiredACG becomes mandatory in appinfo.json, and declaring it on webOS TV 26 turns enforcement on immediately. Every app that reaches embedded subtitles through com.webos.media will lose that feature at the exact moment it complies with the ACG requirement. If a supported replacement exists, developers need to know it before that deadline. If none exists, a large number of video apps are about to lose subtitle track selection without anyone noticing.
Thank you.