During the last couple of months I have had major problems playing high-definition videos in Ubuntu. Generally it's 1080p videos that I have problems with, but I do recall having the same kind of problems with a 720p video a while back. This occurs on both my laptop (with an integrated Intel video chip) and my desktop (Nvidia Geforce 250GTS). It's strange, because I don't think I've had this problem in earlier versions of Ubuntu, and it works fine in Windows on the same machine(s).
The problems occur when trying to play a video that has been encoded to/with "avc1" in an mkv container. I'm not very knowledgeable when it comes to video codecs and such, but from what I've read, avc1 seems like a pretty old codec. How come I have problems with that, when Xvid works just fine?
Suggestions on how to fix this problem?
EDIT: So I've now tried all of the solutions proposed. None of them really worked, although some did lessen the choppiness. I even tried a 720p video using the same encoding, and that was also very choppy. Could someone explain to me why this just will not work, when I can play back other 1080p videos flawlessly?