Choppy high definition video playback

[azenz]

I run Kubuntu 8.04 64 bit with Intel quad core 6600 and XFX GeForce 8600GT 256 PCI-express graphics card @ 620 Mhz GPU speed. High definition video playback (mpeg4 lavc codec) as well as normal DVDs (mpeg2) is a bit choppy since I upgraded from my 17" 1280x1024 to a 22" 1920x1200 pixel screen. Of course almost twice the amount of pixels have to be displayed. I was kind of surprised though that a Windows Media WMV high definition video (1920x1080) plays back fine (also using Kaffeine). Also, the same DVDs play just fine under Windows XP.

I have Nvidia restricted drivers (version 169.12) installed. I tried 4 different players (Kaffeine, mplayer, vlc, KMplayer), results all identical.

My BIG question is: is the limit a) the Kubuntu Nvidia drivers and/or media players, b) my graphics card performance, c) limited graphics card memory (256 MB) and memory speed?

[Snowhog]

Re: Choppy high definition video playback

After you replaced your "smaller" monitor with the larger one, did you reconfigure the nvidia driver??

[azenz]

Re: Choppy high definition video playback

No, I didn't, but have since re-installed the nvidia driver because for some reason it got removed. Nvidia xconfig automatically configures the monitor in xorg.conf as 1920x1200. Through that I also found that without nvidia driver playback is much worse, so at least something is working on my system.

I have since discovered that lavc mpeg4 playback is much smoother at low bitrates (i.e. 2 MBit) but somewhat choppy at 4-5 MBit. But that really shouldn't happen...There got to be a Kubuntu performance bottleneck somewhere since the graphics card can apparently manage the video part of it and the CPU is certainly fast enough.