X-bit labs

Ready to HD: Performance of Contemporary Graphics Accelerators during Video Playback (page 7)

Category: Video

by Alexey Stepin , Yaroslav Lyssenko, Anton Shilov

[ 02/26/2007 | 05:24 PM ]

High-End and Performance-Mainstream Graphics Cards

Playing DVDs is no test for such graphics cards. The CPU load is as low as with the premium-class products.

The Radeon X1900 XT and Radeon X1950 Pro keep the CPU load at the same level, although the latter card has worse technical characteristics. The slightly higher load must be due to the fluctuations of the system during our measurements because the Radeon X1900 XT’s core and memory frequencies are higher while the number of pixel processors doesn’t seem to play any big role at video decoding. The GeForce 8800 has a very low minimum of CPU load, but the average and maximum levels are comparable to those of the AMD solutions.

Decoding DivX SD takes about the same amount of CPU resources as the previous task. The difference is no bigger than 1%, which is negligible considering our measurement method.

The same goes for DivX HD, but the difference is somewhat bigger here, from 2% to 5%. Strangely enough, the GeForce 7950 GT loses to the dual-processor GeForce 7950 GX2 although works at higher frequencies.

We don’t see the above-described anomalies when playing H.264 video: the GeForce 7950 GT quite naturally performs better than the GeForce 7950 GX2 in both 1280x720 and 1920x1080 resolutions. The Radeon X1900 XT and Radeon X1950 Pro perform in a similar manner. An interesting fact, it is when processing the 1080p format that the Radeon X1900 series cards have poor results.

Nvidia’s PureVideo HD engine turns in good results again, contrary to the Radeon X1950 XTX, Radeon X1900 XT and Radeon X1950 Pro that line up in order of descending computing power. However, the Radeon X1950 Pro is quite capable of decoding VC-1 video without putting a big load on the CPU.

These results correlate well with the results of the premium-class products. The CPU load level is generally low, but lower with Nvidia’s than with AMD’s graphics cards.

Graphics cards from the performance-mainstream category are just as good at decoding various video formats as the more advanced products are. Like with the premium-class solutions, the peak CPU load is never higher than 50%, and the average CPU load varies from 6% to 35-37%.