[Openchrome-users] CN700, XvMC and HDTV.

[Thomas Hellström]

Hi, all

I just got a chance to play around with a CN700 board.

Unfortunately it seems like VIA has used the same video core as the 
Unichrome Pro group B series (The K8M800 / K8N800 chips), and all nice 
features that were present on the CN400 seem to be gone.

This includes

    * Mpeg2 decoder AGP DMA capabilities. This means that mpeg data
      can't be queued up to the decoder and the processor has to wait
      for decoder ready. Gone is the small CPU usage and you will
      basically end up at 20% or so with a normal (SD) dvd.
    * Mpeg2 decoder HD capabilities. The hardware decoder is not capable
      of anything above 1024x1024. Smooth software decoding of HDTV
      using a via processor should probably not work very well either.

I'd say xvmc is more or less useless on this chip if the video player 
has a good software mpeg2 decoder.

If the HQV (video prefilter engine) is the same as the other group B 
chips, then CN700 users can also say goodbye to future 
composite-compatible playback.

Out of curiosity it would be interesting to know how CN700 behaves with 
VEXP and VEMP? Does anybody see any HD capabilities with those players?

/Thomas