So basically I have an MKV movie file in a foreign language that did not contain it's own subtitle file. However, when I downloaded it, it came with a separate external SRT subtitle file. My problem is when I try to mux the movie in MP4tools into a format I can play on my ipad/Apple TV. Everything looks fine as it does a passt through of the video, transcodes the audio, and adds the srt subtitles(soft-sub.) When I play it on my ipad/apple tv, there are not options for subtitles. In fact, the only option is Off. On the other hand, I'll open the movie on vlc, I can turn the subtitles on and everything is fine. This also happens when I use Subler. What's weird is, I tried to mux the video without the subtitles. After that, I would then try to mux it again along with the subtitle file. So then, the subtitles would work, but then no audio at all! Does anyone know what's going on? Am I doing this all wrong?