~/.mplayer/config is as follows with 2 profiles:
[fast] vf=eq2 [default] vf=hqdn3d vo=gl:yuv=3:lscale=5:cscale=5 ao=pulse
default one gives good video quality by using the
hqdn3d video filter while the CPU usage is high. If the CPU is not enough for some high-resolution videos, the
fast profile can be used by calling
mplayer -profile fast video.mp4 which will then use the less CPU consuming
eq2 video filter.