I recently bought a Nvidia GT 440, and installed the proprietary nvidia-experimental-310
driver.
Every player seems to be working alright with VDPAU, except Mplayer frontends like SMPlayer.
Any ideas on why this is happening?
If it actually works with mplayer:
mplayer -vo vdpau -vc ffh264vdpau somefile.mkv
in SMPlayer, it should be as simple as setting it to use vdpau in Options / Preferences / General / Video. Set the Output driver vdpau
(it should be there in the drop-down list in a recent enough version, without the need to use the User defined setting).
How did you install the proprietary drivers and are you sure the required libraries for vdpau are installed?