One of the first and best things to observe with MARS is that you actually get some of your CPU cycles back. At lower resolutions, the utilization difference is less, but our 1920x1080 test with the two-minute Pirates 2 XviD trailer on the 9600 GT clearly shows how much CUDA can help. Not only does maximum usage drop from 95% to 74%—an actually practical number if you need to run anything else, such as Outlook or a system backup—but the output time drops by a stunning 81 percent. On the 320x240 version, render time plummets by 92 percent. These are jaw-dropping numbers that could make a serious difference in your everyday usage when converting movies, if, of course, this is an application you actually use in the real-world.
Speaking of which, it seemed important to try out MARS on a full-length video, so we took a 4 GB MPEG-4 home movie and threw it at MARS’s iPod profile. The performance improvement wasn’t quite as mind-blowing as with the Pirates trailer, but come on. A more than 60% acceleration, cutting the completion time in less than half, is nothing to sneeze at.
The interesting bit of weirdness here is that we don’t see the expected amount of scaling improvement when switching to the 9800 GTX. Yes, there’s some improvement on the HD Pirates test, and we shaved a couple minutes off of the 4 GB transcode job, but the 320x240 test showed no gain at all, as if the biggest help came from simply having CUDA and not the number of stream processors actually running it.