Ever since ffmpegX began supporting XviD, I've tried to encode several DVDs (both direct and from VOB files) to XviD .avis.

Whenever I attempt this, the encode begins normally, and the video looks great when previewed. However, the filesize never corresponds to the bitrate that I entered in the video fields. For example, a movie with a video bitrate that ought to make it a 700MB file will often come out at around 1500MB.

I'm certain that I'm doing the settings right, because when I switch the encoder from XviD to MPEG-4 (and leave all other settings the same), the file size is always correct.

So, is this a bug, a problem with my install, or am I just making a mistake in the settings?

Thanks in advance.