What's the best way to encode video (with audio) on the iPhone? It looks like QTKit isn't available... so I might have to link with ffmpeg, but ffmpeg doesn't look like it encodes H.264 (judging from their home page.)
If it is possible, I'm also curious how fast I can expect it to perform on the ARM. I imagine it might take minutes to encode a 20sec movie.
Both ffmpeg and mencoder will encode H2.264 videos when combined with x264, but I'd imagine getting it all running iPhone would be an absolute nightmare, let alone the performance of it once you've got it running.
A while ago I wrote an AVI encoder for the iPhone that used raw file I/O. I just started work on a QuickTime encoder that encodes BMP data into a quicktime container. If it is H.264 you want to encode, I would try making a server that uses QTKit and having your app connect to that for conversion.