Well, it looks like there is going to be a long drawn-out war on AVI versus MP4 containers. So be it. As an iPod-user, I favor MP4.

However, mencoder is strongly geared for the AVI format. I hear that ffmpeg has some mp4 capabilities, though. Any chance of getting them in the GUI? For instance:

==Video Passthru for MP4 containers==
I would LOVE to see a video passthru option when encoding to MP4 XVID (ffmpeg). This would allow us to cleanly convert an MPEG4 XVID AVI to an MPEG4 XVID MP4 file while only re-encoding the audio to AAC. Dear gawd, words cannot describe how awesome it would be to do that!

Note: Yes, I'm aware of DIVX Doctor II, which converts to MOV at least. However, the audio is still in MP3, and I can't run this through FFMPEGX because it lacks a video passthru feature for MOV as well. So, it requires much dancing with a registered copy of Quicktime Pro. Blech.

==MP4 muxing==
No brainer. Windows users have MP4Box with YAMB. Mac users have...well...Quicktime Pro has some limited abilities if you tinker with it enough (and pay for it). I'd rather not pay for two programs. This way, at least then I could split the video and audio from an AVI file, re-encode the audio, then mux into an MP4 container.

Anyhow, thanks for the latest update to FFMPEGX in v0.0.9u. The x264 encoding is top-notch!