This is not hardware acceleration, it's hardware support for YUV colorspace, plus drivers that allow you to write directly to video memory rather than letting the slow broken xf86 drivers copy the image around and convert it multiple times before actually displaying it.

I thought this is what -vo sdl:dga was for. Isn't it faster than vidix? On my Geforce 256 card, for full-screen playback @ 640x480 using libav (default) for mpeg4 decoding, -vo xv seems to be the smoothest and sdl:dga is second, being just a little jerky. I'm using an AMD Athlon 1.2 Ghz. Shaun