Programs for screencapping .AVI files?

I've looked through the memories, but I can't seem to find anything. Sorry if I've overlooked the answer.

I have a .AVI file that I want to take screencaps of. However, I don't know how to go about doing this. I have DivX, but when it plays in DivX the quality is really crappy, and I have VideoLAN, but I can only screencap when hardware acceleration is turned off, and the quality becomes crappy.

So what other programs are there that I can screencap successfully that doesn't decrease the quality and works with .AVI files?

Thanks.