I'm going crazy trying to find a way to convert a .mkv file with H264/AAC to an .mp4 file with the same content (so QT can play it natively). VLC's transcoding doesn't work, ffmpeg doesn't seem to be able to do what I want, and I don't know what to do with the video file I get out of mkvextract (QT won't open it).
Surely someone has done this before.