Video Decoding CPU Utilisation
Video decoding capabilities is one area that S3 appear to have put a lot of effort into with GammaChrome. The video decoding capabilities of the graphics processor should offload more video operations from the CPU to be processed directly on the video core. 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 |
| S18 Nitro | 1.56% | 10.94% | 6.20% |
| X600 PRO | 3.13% | 12.50% | 5.25% |
| 6600 | 3.13% | 17.19% | 10.46% |
| 6200 | 4.69% | 14.19% | 10.71% |
With straight MPEG2 decoding we see that the S18's CPU utilisation is around 6% on average, with the X600 PRO only having a little less than that.
| DiVX (% CPU Usage) | Min | Max | Average |
| S18 Nitro | 14.06% | 25.00% | 18.54% |
| X600 PRO | 12.50% | 23.44% | 17.36% |
| 6600 | 20.31% | 34.38% | 26.59% |
| 6200 | 20.31% | 32.81% | 26.88% |
The CPU utilisation with a file coded in the DiVX codec shows a similar trend as MPEG2 with the S18 having a slightly greater CPU overhead than the X600 PRO, however overall the CPU utilisation is greater than with MPEG2.
| WMV9 - 1080i (% CPU Usage) | Min | Max | Average |
| S18 Nitro | 26.56% | 53.13% | 39.00% |
| X600 PRO | 28.13% | 53.13% | 39.59% |
| 6600 | 39.06% | 62.50% | 48.63% |
| 6200 | 39.06% | 64.06% | 48.82% |
The high resolution WMV9 version of the file shows the average CPU utilisations for the S18 coming out a little lower than that of the X600 PRO on this occasion.
