I convert recordings from WTV to MPG and then to AVI using ffmpeg with the Xvid/MP3 Fast - Medium Quality. The conversions seem to work fine but the output sizes of different shows are quite different. I have two shows that are on the same network that are both HD but after converting one show with the commercials removed at 44 minutes is 1.1 gigs, and the other one with commercials (they should have been removed but weren't, at least it didn't work today) at 63 minutes is 798 megs. Another show on a different network without commercials at 37 minutes is 386 megs. Can somebody explain why these shows would vary so much in their output size and if there is anything I can do to control it? Even if I can change the bit rate somewhere I would assume that it should be using a fixed rate already so it seems like the sizes should be more proportional.