[vlc-devel] VAAPI playback on PCI video card

[Yuval Levy]

Dear VLC developers

first: mega kudos to all of you.  Yesterday I was able to use VLC to play AVCHD 
videos (24Mb/s) at full screen on a low powered AMD machine (nVidia chipset 
with on board video).  Amazing performance on such "low" hardware!

Next, I tried to go lower (0dB custom nettop).  The motherboard is Intel's 
D945GCLF (the first Atom board) with a fanless ATI video card (Radeon HD 4350).  
it's PCI (the Mobo does not have PCIe nor AGP).

The system is Kubuntu 10.04, with ATI proprietary drivers (the latest from 
ATI's website, previous ones including those in the 'buntu repos don't work) 
because AFAIK [0] only works with the proprietary drivers; and the fglrx 
version in the 'buntus repo is too old to be supported.

This is the output of vainfo:

$ vainfo
libva: libva version 0.31.1-sds1
Xlib:  extension "XFree86-DRI" missing on display ":0.0".
libva: va_getDriverName() returns 0
libva: Trying to open /usr/lib/va/drivers/fglrx_drv_video.so
libva: va_openDriver() returns 0
vainfo: VA API version: 0.31
vainfo: Driver version: Splitted-Desktop Systems XvBA backend for VA API - 
0.7.2
vainfo: Supported profile and entrypoints
      VAProfileMPEG2Simple            : VAEntrypointIDCT
      VAProfileMPEG2Main              : VAEntrypointIDCT
      VAProfileH264High               : VAEntrypointVLD
      VAProfileVC1Advanced            : VAEntrypointVLD


when I try to play one of the AVCHD files with VLC 1.2, it stutters.  For a few 
frames it is smooth, then it kind of pauses, shows a couple of "pixelated" 
frames, then it catches up to smooth playback for another few frames.  Audio 
is OK.

Am I demanding too much of my low power hardware, or is this something that 
can be fixed?  I understand PCI does not have as much bandwidth as PCIe, but it 
is only the compressed video stream that has to go through the PCI bottleneck 
and once decoded the GPU can output directly to the display, or am I missing 
something?

If this can be fixed, where do I start investigating?

thanks
Yuv

[0] http://www.splitted-desktop.com/~gbeauchesne/xvba-video/xvba-
video_0.7.2-1_amd64.deb
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