Video Decoding CPU Utilisation
The video decoding capabilities of the graphics processor should offload more video operations from the CPU to be processed directly on the video processor. Here we'll take a look at the CPU utilisation under three decoding operations, DVD MPEG-2, High Definition (1080i) WMV9 and DiVX in order to see which board provides the lowest CPU utilisations under each of the formats, using the Catalyst 5.3 drivers. In each case we used the same Terminator 2 trailer clip found at Microsoft's High Definition Video site, converted it into the other two formats and played each one back through Windows Media Player 10, monitoring the CPU utilisation via the Performance Monitor in the Microsoft Management Console.
| DVD MPEG2 (% CPU Usage) | Min | Max | Average |
| X1800 XT | 6.25% | 12.50% | 9.03% |
| X1800 XL | 4.69% | 12.50% | 8.08% |
| X850 XT PE | 1.56% | 6.25% | 4.19% |
| X800 XT | 0.0% | 7.8% | 3.8% |
It would appear that the MPEG2 decoding on the X1800's is not yet fully optimised in the drivers, seeing as the CPU utilisation is higher than their predecessors.
| DiVX (% CPU Usage) | Min | Max | Average |
| X1800 XT | 12.50% | 21.88% | 16.89% |
| X1800 XL | 12.50% | 21.88% | 17.30% |
| X850 XT PE | 12.50% | 21.88% | 16.06% |
| X800 XT | 12.50% | 21.88% | 16.37% |
The CPU utilisation with DiVX for both the X1800's is in the same region as the previous boards.
| WMV8 - 1080i (% CPU Usage) | Min | Max | Average |
| X1800 XT | 18.75% | 46.88% | 34.31% |
| X1800 XL | 17.19% | 46.88% | 35.19% |
| X850 XT PE | 25.00% | 50.00% | 34.22% |
| X800 XT | 20.31% | 50.00% | 34.05% |
As with DiVX, the CPU utilisation for High Definition WMV playback on the X1800's is similar to the previous generation of Radeon's.
The X1800's also have hardware acceleration for H.264 decoding, however there is presently no DXVA interface for this so it can't be tested through Media Player.
