[PD] system requirements video

[Daniel Heckenberg]

Hi Chris, Johannes, list

On 10/9/03 6:21 AM, "chris clepper" <cgc at humboldtblvd.com> wrote:
> Starting with OSX 10.2 all textures can be uploaded using DMA
> resulting in 0% CPU time for the transfer.  Plus 10.2 can handle
> non-power-of-two texture sizes and YUV pixels for even more
> efficiency.  This applies for both ATI Radeon (not Rage) and Nvidia
> Geforce hardware on OSX.  Of course GEM fully supports these
> features. ;)
> 
> Windows does not feature any of these enhancements in it's standard
> OpenGL implementation, so significant CPU time can be spent handling
> the texture uploads.  There might be some vendor specific extensions
> to enable fast texturing, but to my knowledge none of them have been
> implemented in GEM.

Yes... Microsoft is try to get openGL to quietly rot on the PC.  I've done
some testing with nVidia's Pixel Data Range extension for Windows (which
allow AGP texture transfers using asynchronous DMA) but (surprisingly) the
performance improvements were not at all spectacular so I didn't implement
them in GEM.  This extension is also available for Linux when using recent
nVidia drivers.
http://oss.sgi.com/projects/ogl-sample/registry/NV/pixel_data_range.txt

I haven't seen reports from anyone (except nVidia) getting significant
improvmements using that extension.  It's probably time I played with it
again though, as texture upload certainly is an enormous bottleneck for
Gem...

> Windows will be getting system wide support for
> using video as textures, unfortunately it will be for Direct3D and
> won't be released until 2005 or 2006 (as part of the Longhorn GDI).

I'm no windows zealot so I'm not going to start a platform battle... but
DirectX 9 has the ability to "directly" use video as textures and indeed
does so by default when building media graphs in DirectShow.
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnwmt/html/
vmr_d3d.asp

I don't believe that there are YUV texture formats but I think that AGP DMA
transfer does get used... does anyone know more?  It's hard to get this info
out of DirectShow/DirectX.

Longhorn is supposed to bring Quartz-Extreme style "everything is a
texture", "everything is done on the GPU" to replace the old GDI interface
but video playback is already being done with the 3d pipeline.

Daniel