I have an MKV (an Italian version). I have extracted the H264 and the unwanted (Italian) AC3 audio. Now, I'd like to remux it with an English audio track (I have).
The problem is, the English track is quite long (around 1 hr. 50 mins or so...) while the H264 track is 4 mins behind. Is there a way I can reduce the duration of the audio (by some approximation) so that I can resync with the track and mux it into MKV container?
Actually, the audio delay at different positions made me suspect that the rate of AC3 track is quite fast (relative to the H264 track). And now, with mkvmerge, I changed the FPS to the default
24000/1001p and finally, it synced with the audio. Now, it's playing perfect...