I'm wondering if anyone else is having problems using the audio pass-through for MP3 audio in ffmpeg (or ffmpegx)? I've never been able to get ot to work properly, as ffmpeg always identifies the audio as MP2 audio instead of MP3, making the audio unplayable in both QT and VLC. If I use the force format switch it just re-encodes it to MP3.
My current way of making DivX avi files is to first use ogmtools to make an ogm file including video and audio and then piping it through mencoder (since I don't know how to get mencoder to accept different source files for audio and video) using pass-through.