Any utility to mux AAC audio track from .rmvb file into MP4?

[whileloop]

I currently use mkvmerge and mkvextract from MKVToolNix to extract AAC audio track from .rmvb file to a ADTS-AAC (.aac) file. Then mux the .acc and .264 into mp4 by MP4Box. But MKVToolNix is a little too big to be included into another package.

I tried ffmpeg, but ffmpeg seems have bugs handling the timestamps of rmvb file.

Is there any other command line utility that can extract AAC audio from .rmvb or mux into mp4 without re-encoding?

[roozhou]

That is also what i am looking for.
Here is the result from my test with ffmpeg's aac demuxer/muxer:

mkv/mp4/rm/adts -> adts OK
adts -> mkv ................ Broken
anything -> rm ............ Broken
anything -> avi ............ Broken
rm/avi/mkv/adts -> mp4 . Broken
rm/avi/mp4/mkv -> mkv . OK
mp4(non ipod) -> mp4 ... OK
anything -> ts ............ Broken
ts -> anything ............ Broken

IMHO the best way is to fix ffmpeg's broken aac demuxer/muxer ... on your own. It may take years for ffmpeg-devel to fix these bugs.