To quickly explain the term, video encoding is the process of taking a sequence of images (or a video file) and compressing that into a different digital video format. For example, let's say you have some home videos from your digital Handycam but you want to play it on your iPod video: you have to encode it to an iPod compatible format first.
Video encoding is a fundamental difference between the capabilities of Avivo and Purevideo. ATI claims that Avivo allows for accelerated video encoding. Nvidia makes no similar claim with Purevideo.
There is a lot of talk on the Net about ATI GPUs being flexible enough to use as general-purpose processors. Not only have Radeon X1900 cards been used in helping molecular simulation with the folding-at-home project, but AMD has even re-released a version of the X1900 as a "stream coprocessor." Now imagine all of this power used to speed up the rendering of video files!
Well keep imagining, because this isn't the case.
When I first heard about the Avivo encoding feature, I hastily assumed (based on the buzz) that ATI GPUs would assist in the rendering of video files, providing some hardware acceleration... not so. The Avivo encoder is traditional software and utilizes only CPU power. It has nothing to do with the video card except that it requires a Radeon X1k series card to be present in order to work.
To make sure this was the case, I checked CPU utilization with the Avivo encoder vs. the encoder in Premiere. There was no difference, as the CPU utilization rate was 100% in both cases.
To be doubly sure something else wasn't happening behind the scenes, I closely watched the GPU temperature in both scenarios. Once again, the GPU temperature didn't move one iota, and video memory wasn't utilized any more than when the processor was in idle mode, suggesting that the Avivo encoder has no hooks in the ATI GPU at all.
For me, the real appeal was the thought of using all that Radeon graphics horsepower to accelerate the encoding process. That is likely to remain a dream at this point; with AMD marketing the "stream coprocessor" cards, there is probably very little incentive at AMD/ATI to add any co-processing functionality to Radeon cards, even if it's just for video encoding.
Not to ignore the good stuff though, I should mention that the Avivo encoder is a nice bit of value-added software. It is a fairly fast video encoder and is a great simple tool for the quick and dirty jobs. But the weaknesses are pretty glaring: Why can the encoding program only be accessed in the basic Catalyst driver panel? It's not in the advanced panel because I wasted a lot of time looking for it. Why isn't it a separate application, launched through the ATI tray icon? Without specific instruction, it's almost impossible to find. In addition, the encoding options are sparse at best and offer little or no control for someone who knows what they're doing.
I would have liked to do a comparison of Avivo vs. other encoders, but the lack of control or explanation in Avivo makes it almost impossible for an apples-to-apples comparison. Without being able to force the Avivo encoder to produce identical output to the competition, a comparison is fundamentally flawed. I even tried to match up the output quality with some other encoding tools, but the output was different enough that a benchmark graph would be almost completely meaningless.
Suffice to say that the Avivo encoder is a great bonus for people who need a fast, no-frills encoder. But it's not the killer app it could have been if it had hooks in the X1900 GPU. I would love to see the Avivo encoder interface with ATI video processing hardware in the future; let's keep our fingers crossed.