The main problem is, with sequential vob files the video and audio is continuous. That's why they can be indexed as a single file. There's no guarantee that'll be the case for MP4s though, or that the audio and video in each MP4 would be the same length.
Even if you appended them as a single MKV and encoded the video in one go you might still have problems, although after encoding, if you opened the encoded video with MKVToolNixGUI, added the original MKV, de-selected the original video and remuxed, there's some chance the audio and video would still be in sync, although if the audio in any of the MP4s happened to be longer than the video, that probably wouldn't work either.
|