MP4 to MKV with AC3 and back to MP4

[Biggles]

I have a MPEG4 file with separate AC3 stream, Sub stream and Idx stream.

I wish to split out the audio in the Mpeg4 and add the AC3 stream and sub stream such that the file will be streamed to a PS3

How do I do this?

[Comatose]

AFAIK, the PS3 can't handle AVC+AC3 in MP4. You have to use mkv2vob to create an AVC+AC3 VOB which the PS3 can play.

[Biggles]

OK
How do I convert a mp4 file back to mkv and strip out the audio and then attach the new audio when converting to a vob

[Oleg Rode]

Sorry for my English...
I have a MPEG4 file
AVC or DivX/XviD?