your sample amv files will surely never jump. I am sure the problem is not due to the player, but the amv files itself. If the converted file is OK , then it will never jump. But The amv filkes I converted using the converting tools even jump when I play them in my computer and not just in my mp4 player. So, I am sure the problem does not come from my mp4 player, the amv file itself has problem. As I mentioned before, I think this is due to the way of the tool selecting video frames from the original viode files.

Eg. My original avi files has a frame rate of 30 per second, but the amv file only have , let's say, 10 per second, but does the converting tool choose the original frames in an even way? ie. the 1st, 4th, 7th......... ? Or just simply choose the first 10 original frames (ie. the original first 0.33 second) and then become the final 10 frames in the amv file ? How even does the program choose the frames from origianl video file ?