I wonder how fast these two mainstream brands handle texture upload on different OS'es.
It may not be very optimized in the driver since this operation is rarely used during gameplay, but it's a potential bottleneck for video processing. I expect major performance differences here.
Did anyone compare nVidia vs ATI on different OS's on this aspect?
We actually have fairly extensive data on this.
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. 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).
Linux is closer to Windows than OSX as far as drivers go with Nvidia hardware, so you can expect similar texturing performance.
I can post measured performance data between Win32 and OSX GEM if you are interested.
cgc
j#|@