With MPEG-2 video becoming increasingly popular, hardware video acceleration has become an important feature for today's graphics adapters. Buzzwords like motion compensation, de-interlacing, moiré, and scaling are thrown around freely and it isn't hard to get hit with unfamiliar terminology. To simplify the situation, we will briefly explain the features of the top performing cards.

One of the most popular of these buzzwords is motion compensation. Taken from our article on Benchmarking DVD On The PC:

"Basically, motion compensation attempts to match information from the previous frame to the information in the frame being decoded. The algorithm then has an acceptable chance of "block matching" sections of the current frame to previous frames and saving the decompression work it would otherwise undergo. Although it seems like more work than would be otherwise saved, a hardware implementation of motion compensation on a graphics chip can offload up to 30% of the CPU requirements, reducing the minimum system requirements for full frame software playback. Please note that a software decoder must support the hardware manufacturer's specific motion compensation algorithm for gains to be realized."

Both the Radeon and the GeForce2 are equipped with motion compensation engines supported by the leading software decoding titles.

Inverse Discrete Cosine Transform (IDCT) is another performance feature that aids in the decoding of the MPEG-2 stream. Serving as the method for de-compressing the video data, IDCT performed onboard the video card further enables the CPU to be freed of the decoding process. Of the three chipsets in our shootout, the Radeon is the only one to support this feature. Judging video acceleration is significantly more difficult than 3D performance. Video 2000, the only available video benchmark, is not compatible with the Radeon because of ATI's advanced de-interlacing technique, so we are forced to do a subjective test. On average, the Voodoo5 consumed nearly 25% of our 1GHz Pentium III while playing the movie Face/Off. The GeForce surprised us by hovering around 30% and the Radeon remained close to 15%. It was interesting to observe that the Radeon was the only card to correctly display the alpha menu highlights in the root menu of Face/Off (the crosshairs). For the purpose of resizing MPEG-2 video, the Radeon makes use of a 4-tap horizontal/4 tap vertical scalar while the GeForce2 has an integrated 5-tap horizontal/3 tap vertical scalar.

Without a doubt, video acceleration belongs to the Radeon. S3 was the only company to ever rival the video features that ATI has incorporated, but that is another story entirely. NVIDIA's GeForce2 takes second, mainly because 3dfx forgot to include any video acceleration features into the Voodoo5. Whoops, maybe next time, guys.

And now... on to the benchmarks!