Consider giving dvbcut a look ( http://dvbcut.sourceforge.net/ ) and comparing it to avidemux.
It doesn't do nearly as much, but I've had much better success with it (specifically, it
doesn't cause A/V desync. like I have experienced with avidemux) and it can be significantly
faster - it only re-transports rather than re-encodes and, for files that come from ivtv,
means I can go right from ivtv to dvbcut to DVD without ever once re-encoding (only changing