jerky vcds

[linut]

I've been making vcds from downloaded divX avi's using avidemux -> mplex -> vcdimager -> cdrdao as per the instructions on the avidemux website. Recently I've been running into xvid avi's the process has failed me. I have xvid support in avidemux and the resulting mp2 and m1v files seem fine until I multiplex them. When I play the generated mpeg file it is smooth in mplayer, but you can see mplayer's counter going crazy and as a vcd in my dvdplayer it's jerky as a monkeys uncle. Do I need to change something in avidemux or mplex? - Thanks