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NVIDIA GeForce 7800 GTX
by Damien Triolet et Marc Prieur
Published on June 22, 2005

Windows Media 9 decompression
When introducing the GeForce 6800 in April 2004, NVIDIA announced taht this chip was able to decode in hardware MPEG1, MPEG2, MPEG4 and WMV9 video, as well as to encode in hardware all MPEG formats.

These functionalities were unavailable at the release. We had to wait until the end of 2004 to find out what was behind the PureVideo name and until the end of May 2005 for Microsoft to release the DXVA patch that enables acceleration for Windows Media videos decoding. For the moment there´s still no question of encoding acceleration and even worse, the GeForce 6800 GT & Ultra have a bugged PureVideo engine which forbids WMV9 decoding acceleration. This functionality is then restricted to graphic cards such as the GeForce 6200 or 6600.

With the GeForce 7800 GTX, NVIDIA finally has a high end solution capable of accelerating WMV9 videos decoding. We verified this by measuring the processor use rate during the Step Into Liquid video read in 1080p version with an Athlon 64 processor clocked at 2.8 GHz:

On average, with the Radeon X850 XT PE the CPU usage is 39.5% instead of 41.4% with the GeForce 7800 GTX and 68,6% with GeForce 6800 Ultra. There is no doubt that the WMV9 acceleration is now functionnal.

It is interesting to note that there is some talk of future H.264 decoding acceleration. The H.264, is a part of the MPEG-4 norm (the other denomination is MPEG-4 Part 10), and goes even further for compression at the expense of encoding and decoding complexity. A semi hardware solution by the graphic processor would be welcomed.

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