PureVideo: Features & Performance
Next we took another look at Digital Video processing capabilities between the two competing core GPU architectures, "PureVideo" technology at work for NVIDIA and "AVIVO" driving ATI.
To characterize CPU utilization when playing back WMV HD content, we used the Performance Monitor built into Windows XP. Using the data provided by Windows Performance Monitor, we created a log file that sampled the percent of CPU utilization every second, while playing back the 1080p version of the "The Living Sea" video available on Microsoft's WMVHD site. The data was then imported into Excel to create the graph below. The graph shows the CPU utilization for a GeForce 7900 GTX, a GeForce 7800 GTX, and a Radeon X1900 XTX using Windows Media Player 10, patched using the DXVA updates posted on Microsoft's web site (Updates Available Here).
Average CPU Utilization (Athlon 64 FX-55 @ 2.6GHz)
|GeForce 7900 GTX||GeForce 7800 GTX||Radeon X1900 XT|
These flagship GPU architectures are roughly on par, CPU utilization-wise, when playing High-Def content in Windows Media Player 10. The two NVIDIA GeForce 7 series cards put up slightly lower utilization levels than the Radeon X1900 XTX but as you'll see in the following section, this variance is minor and it's not all about low CPU overhead. And depending on which video is being played, the utilization can change to favor either architecture.
Next up, we have a new addition to the HotHardware testing arsenal, the HQV DVD video benchmark from Silicon Optics. HQV is comprised of a sampling of video clips and test patterns that have been specifically designed to evaluate a variety of interlaced video signal processing tasks, including decoding, de-interlacing, motion correction, noise reduction, film cadence detection, and detail enhancement. As each clip is played, the viewer is required to "score" the image based on a predetermined set of criteria. The numbers listed below are the sum of the scores for each section. We played the HQV DVD using the latest version of NVIDIA's PureVideo Decoder on the GeForce 7900 GTX, and as recommended by ATI, we played the DVD on the ATI hardware using Intervideo's WinDVD 7 Platinum, with hardware acceleration enabled.
When the ATI's X1K family of products first launched, their score in this benchmark was below 40 points. With the latest set of Catalyst 6.2 drivers though, video playback quality is vastly improved. And even more improvements are on the way in the Catalyst 6.4 drivers. The biggest boost to ATI's score comes by way of the eight individual film cadence test and the noise reduction tests. As things stand today, NVIDIA's PureVideo technology, from an image quality perspective, doesn't compete favorably to ATI. For playing back DVDs, or similar digital video files, ATI's X1K family of cards and the new X1900 XTX are the yardsticks to measure by.
However, we would offer the caveat that you should watch this space closely, as both companies will be releasing driver revisions in the coming months that will reportedly offer significant improvements in image quality. We saw a future NVIDIA driver release up and running, which supported all of the cadence tests, and also did a great job with noise reduction and sharpening in the film detail tests. ATI too is improving their noise reduction algorithm and introducing image sharpening in a future release. We suspect both companies will offer similar performance in this benchmark by the late-April to May time frame.
We should also mention that NVIDIA has been working with partners to enable full PureVideo support with video playback applications that are DXVA compliant. That means applications like WinDVD, PowerDVD, and Nero will benefit from PureVideo and end-users will no longer have to purchase NVIDIA's decoder separately to experience the benefits of the video-engine built into their cards. NVIDIA also offers H.264 acceleration on all cards in the GeForce 7 and GeForce 6 series of products (excluding early NV40s with the first-gen PureVideo engine), which will accelerate HD videos when Blue-Ray and HD DVDs hit the scene in the coming months.