[herg]

First, here's a log:
http://pastebin.com/CgtdtvC0

Debug logging is NOT turned on, but I can grab a debug log when I have time if needed.

Hardware is an Acer Revo 1600 connected via HDMI for both video and audio.

I just got a new projector, and as a result, I'm going from 720p display to 1080p. It's a new Ubuntu 10.10 install and a new XBMC Dharma install. I get lots of frame drops, despite VDPAU decoding being enabled. I messed with settings, and the one thing I can find that makes it better is dropping the scaling method from Bicubic to Bilinear or NN. Even at NN, the 1080p Avatar video drops occasionally.

So, I decided to try a DVD rip, and it has problems with Bicubic also. Fps stays about 20 and video falls behind, then catches up quickly. Switching to Bilinear makes this 480p source work fine.

With either the 1080p or 480p source, the CPU utilization remains low.

Switching to 720p output also fixes the problem.

[bobo1on1]

Turning off desktop effects in gnome should help, but ion systems generally max out at 30 fps with these scalers.

[herg]

I'm pretty sure that desktop effects are off.

If I'm reading the log correctly, though, my output refresh rate is 109 Hz (weird number). Does this mean it's trying to run the scaler at 109 fps? If so, I'm guessing that dropping the refresh rate should help. That "adjust refresh rate to match source frame rate" option sounds useful. I'll give that a try.

I guess it would be a feature request, but it would seem to make sense to not run the scaler if source and output resolution is the same. Maybe I'm overlooking something, though.

[bobo1on1]

The strange refreshrate is because dynamic twinview is on, you need to turn that off in xorg.conf.
The scaler does not run at the refreshrate, it runs at the video fps.
Turning off the scaler if the output size is the same as the input size is probably a good idea, but it still won't make it any faster.

[herg]

Thanks, I disabled Twinview, and I get 60 Hz (along with others) now.

I've tried a few different 1080p/24 sources, and I get occasional jerky video with all of them, even with NN scaling.

I guess I'm stuck making a choice between two of the following three:
1080p output
Completely smooth video
Acer Revo 1600

Anyway, if it's normal for Ion systems, at least I know. Thanks for the info.

[bobo1on1]

You could try and follow http://forum.xbmc.org/showthread.php?tid=70068