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ATI Stream: Finally, CUDA Has Competition
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For those of you who wondered exactly which “Pirates 2 trailer” I was testing with in the CUDA article, here it is again: Pirates of the Caribbean: Dead Man’s Chest, a 71 MB, 1280x528 file (plus black bars) in DivX AVI format. Let’s say you have a thing for playing movie trailers on your PlayStation 3. I picked the 720x480 profile as a target. This should be a straightforward test with neither player supporting decode acceleration of the source and both accelerating the target.

The outcome here was a little odd for two reasons. First, we finally see a slight disparity in CPU-only encode times, although a 7.6% variance on a three minute file is nothing to fret about. Second, even though Nvidia had the higher CPU-only time, it manages to scoot just past AMD on the GPU-assist score, beating Stream by 11 seconds, or 13.5 percent, and contradicting our earlier results.

The next test was purposefully weighted toward AMD by selecting an MPEG-2 source, which Stream accelerates but CUDA does not, and converting into AVC for the iPod Touch. This is actually one of the more important tests because I selected a 298 MB VOB file—the trailer video from the Mr. and Mrs. Smith DVD, making this representative of performance for when you want to encode your DVD rips into H.264. We have AMD accelerating both ends of the transcode while Nvidia is only lifting the back end. The results seem to mirror this exactly. Both cards show the same CPU-only times, but whereas CUDA cuts 35.5% off the transcode time, Stream shows a 108% improvement. In my mind, this test above all others shows Stream’s best value.

 Yeah, I skewed the last test toward AMD, but that doesn’t change the fact that Stream is doing something CUDA can’t.  Score: AMD 3, Nvidia 3.

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