Embedded ASS subtitle track in streamed video?

Question

We'd like to build a small specialized clone of the ill-fated popcorn-time project, that is to say a node-webkit frontend for peerflix. The videos we'd like to play are mkv files that have embedded ASS subtitle tracks, and we can't seem to get the embedded subtitles to show up: while VLC nicely shows them, html5 video players in webkit-based things don't, not even in Google Chrome (so it's not a matter of Chromium's reduced codec support).

Now, I'm a bit out of our depths here, I don't really know much about these things, but it seems to me the media engine underneath webkit just ignores the ASS subtitle track here. Is it because it's ASS? Is it a matter of codecs somehow? Or is it, after all, a html5 thing? Now, the html5 video "living standard" mentions that "captions can be provided, either embedded in the video stream or as external files using the track element" - so the feature is at least planned, but I do realize that implementation is lacking. However, given that node-webkit uses ffmpeg as the underlying engine, it seems strange to me that the subtitles are not picked up at all.

Could someone more knowledgeable please advise us the problem? Also, is there anything we could do about it?

Extracting the subtitles beforehand is not an option, though I have been playing with the idea of extracting the subtitles on the fly, and feeding that stream back to the player - I had some modest success with this, and it looks like it could be done with some effort, but I'm really out of my depth here, and the whole idea is pretty contrived anyway.

However, I find it improbable that nobody has run into this problem before, hence this question: is there any way to show embedded (ASS) subtitle tracks in a streamed video in node-webkit?

Answer 1

Not sure if this would help but according to this page node-webkit doesn't ship with codec for patented media formats. They do have a few suggestions on the page, one of which is to compile your own node-webkit.

You could try using Popcorn Time's ffmpegsumo file which is what I used when I needed mp3 support and Chrome's version didn't work. Although, I don't know if that supports ASS subtitle format(considering its use, I would think it has to).

Note: I would have commented this answer but unfortunately I don't have commenting privileges yet. A couple of upvotes sure would be nice ;)