1920x1200 video playback performance

[azenz]

I am running Kubuntu 8.04 with a Geforce XFX 8600 GT 256MB / 540Mhz and a 1920x1200 pixel resolution screen. I use the 177.82 driver and the performance tweaks suggested on this site. 2D performance is generally acceptable but video playback is not very smooth, both for regular DVDs and especially for high definition video (MP2) files taken with my HD camcorder. Under Windows they play fine (I have a Q6600 2.4 Ghz quad core). Especially HD playback is not very smooth at all, lots of vertical banding appearing there. Is that supposed to be the best to expect from a 8600 GT under Linux?

[azenz]

Is HD resolution video playback not much of a concern within the Nvidia community?

[gbil]

Originally Posted by azenz

Is HD resolution video playback not much of a concern within the Nvidia community?

There is a search function in the forum.

[adamorjames]

Isn't VDPAU suppose to fix this? or is there something I'm not seeing..

[azenz]

I did search around but could not find any information that was really helpful (and some relevant posts had no solutions in them).

I don't think that VDPAU is the issue here because I have a fast CPU and MP2 playback at full resolution only uses 40-50% cpu (one core). What I get is like a banding effect which is quite noticeable in panning scenes, not just HD resolution video but also simple PAL (although there it is slightly less noticeable). Helpful comments would be much appreciated, especially since I managed to solve the terrible 2D performance problem with upgrading to the 177.82 driver and using the recommended settings. Unfortunately, that didn't solve the video playback problem...

[gbil]

Originally Posted by azenz

I did search around but could not find any information that was really helpful (and some relevant posts had no solutions in them).

I don't think that VDPAU is the issue here because I have a fast CPU and MP2 playback at full resolution only uses 40-50% cpu (one core). What I get is like a banding effect which is quite noticeable in panning scenes, not just HD resolution video but also simple PAL (although there it is slightly less noticeable). Helpful comments would be much appreciated, especially since I managed to solve the terrible 2D performance problem with upgrading to the 177.82 driver and using the recommended settings. Unfortunately, that didn't solve the video playback problem...

VDPAU IS the answer. 50% of 2 cores is 100% of 1 core since your player uses only one cpu and without VDPAU you don't get hardware acceleration from the GPU, so you have reached the maximum cpu utilization and that is why your video isn't smooth.

[conky]

He says he sees it for standard definition mpeg2 as well, so it can't be a CPU utilization issue. My guess is that he doesn't have sync to vblank turned on for Xv and is seeing tearing.

[azenz]

No sync to vblank turned on for Xv: that sounds really interesting and I have no idea what it means. Could someone tell me how to turn it on so I can check whether that is the issue? Thanks!

Gbil, what do you mean by "50% of 2 cores is 100% of 1 core"? I only saw 50% cpu utilisation on ONE of the four cores, not on two. I agree that PAL playback shouldn't be a CPU issue...

[Dragoran]

Yo can find it in nvidia-settings -> "X Server XVideo Settings" but this should be on by default.
Are you using muliple screens?
Compiz?

[azenz]

I use compiz but only one screen. In NVidia settings I have "sync to XV" checked, so probably meaning it is enabled. I disabled it to see if that made a difference but it didn't.

When I said banding effect what I mean is that vertical chunks of video (usually about 1 inch in height on the screen) are at times displayed with a slight delay, which creates like a flickering effect. It is as if the video cannot be displayed at full speed at the required refresh rate. The limit in my opinion can only be the Linux driver performance or a related setting.

[Dragoran]

Enable "sync to vblank" in compiz, set the refresh rate to your monitors refresh rate and disable "detect refresh_rate" .

[gbil]

Originally Posted by azenz

Gbil, what do you mean by "50% of 2 cores is 100% of 1 core"? I only saw 50% cpu utilisation on ONE of the four cores, not on two. I agree that PAL playback shouldn't be a CPU issue...

My mistake then, I read it a 50% of total thus 100% of one - you never clarified how many cores you have.

Try the refresh rate and also post a bug report, to have your whole config.