i5-2520M (Sandy Bridge) using GPU acceleration makes 1080p a lot worse

[bean]

I am using Arch Linux, and if the switch "Use GPU acceleration (experimental)" in VLC Input & Codecs part is off then a H.264 1080p MKV plays at around 40% CPU. Not too bad. But I would prefer less CPU so I switch on GPU acceleration. As verified by looking at vlc -vv output I see vaapi used now (it wasnt before). Surprise: the CPU is now 50-60% and the video is choppy as hell. vainfo reports:

VAProfileMPEG2Simple : VAEntrypointVLD
VAProfileMPEG2Main : VAEntrypointVLD
VAProfileH264Baseline : VAEntrypointVLD
VAProfileH264Main : VAEntrypointVLD
VAProfileH264High : VAEntrypointVLD
VAProfileVC1Simple : VAEntrypointVLD
VAProfileVC1Main : VAEntrypointVLD
VAProfileVC1Advanced : VAEntrypointVLD

So what's going on here?

[bean]

I forgot to add, I am running KDE 4.6 with Desktop Effects on. If this matters.

[darkbasic]

Did you try with desktop effects off?

[Kano]

Basically vlc is very ineffective using vaapi. Much better are xbmc or mplayer vaapi.

[bean]

Desktop effects off solved it seemingly with videolan.

Desktop effects on. xbmc was jerky though different ways than videolan. Crashed KDE when I tried to quit.

mplayer-vaapi works even with desktop effects, and the CPU is below 5%. But I get the dreaded Your system is too SLOW to play this! message and very very occassionally a few frames drop (along with the audio). That was with -vo vaapi. If I add -va vaapi as well, this leads to a KDE crash after a few minutes.

All in all either switch off desktop effects or go software or your KDE crashes.

[Kano]

you need -va vaapi AND -vo vaapi otherwise it is not accellerated.