XvMC Quality?

[ejarosek]

Should XvMC based decoding be equivelent to xv? On my machine (running MythTV) whenever I enable XvMC it makes the video quality look blocky and crappy. This is for playing DVD's or watching analog TV from the PVR-250's. The video is being scaled up to 1024x768. HDTV video looks good using XvMC and the machine is not fast enough to play with the Xv driver.

One note: I am not able to use XvMC when AGP is enabled. Any application using it locks up. I have to set Option "NvAGP" "0" (disable AGP) to get XvMC to work. Should I return the 6200 and pick up a 5200 instead?

My system:

Gigabyte GA-7N400 Pro2 (Rev 1) NForce II Mb
Athlon XP 2600+
512MB RAM
PNY Verto NVidia 6200 256Mb
2x Hauppauge PVR-250
pcHDTV HD3000

[Thunderbird]

The geforce 6200 (the same for 6600 and 7800) doesn't support hardware video overlay this means it doesn't do Xv using overlay in hardware anymore. The drivers use simple blitting (a simple 2d operation).

The image quality might improve if you let XvMC use the 3d engine of your GPU instead of Xv. Add the line Option "XvmcUsesTextures" to the screen/device section of your X config file. Perhaps it helps.

[ejarosek]

What are the plans going forward for the 6200, 6600, 7800 line? Will the linux drivers eventually take advantage of the PureVideo hardware? For htpc use (including HDTV) am I better off staying with the 5200 line which uses the hardware overlay?

Thanks for the response.

[Thunderbird]

I don't know what Nvidia's plans are. These days other vendors like Ati and Via also have something like PureVideo. The main issue why there's no PureVideo support right now is that there's no X/Linux standard for yet. It might be an option to extend XvMC for this purpose but this isn't something Nvidia should do alone.