chyron8472 said:

I suppose it is a question related to technical help regarding AVCHDs in general instead of Harmy's edit specifically. Sorry. :p

I may be missing something. but I thought mp4 files generally consist of H.264 video and AAC audio.

IIRC, Harmy AVCHD and mkv video is already H.264, so all you should need to do is convert the desired soundtrack to AAC and mux together with the video into an mp4 container: much less effort than converting the video.

It may also be possible to use MP3 audio instead of AAC, but I don't have much experience with Apple proprietary formats.

Technical queries should probably be directed to another forum section.