After a bazillion tests I finally found an encoder and settings I'm happy with, except XviD with mencoder seems to have audio just slightly out of sync. I tried encoding with VisualHub which does pass the -async flag and it does not have the problem. It kind of sucks that you can't pass additional arguments through ffmpegX, unless I'm missing it somewhere. I have about 300 VHS tapes I'm planning on capturing and encoding, so streamlining the process is very important to me. Messing around with demuxing and fixing the offset isn't high on my list. It's bad enough ffmpegX won't work with edited QuickTime reference movies.

So... I guess what I'm getting at is is there any way to pass an async flag in ffmpegX, and if not, is there any chance custom flags will be added in the (near) future? Or is there some other easy way I can fix the audio sync issue? Thanks.