Video Card Roundup - DVD Quality, Features & Performance - October 2000

The next big step – ATI’s Rage 128

Another big contributor to the evolution of DVD playback on the PC was ATI.  ATI’s Rage Pro chipset, one of the first chipsets ever to be used on an AGP card, also featured a Hardware Motion Compensation engine, even precluding the Savage3D’s HWMC engine.

However ATI did not stop there, in the next incarnation of the Rage family, the Rage 128, ATI took two more DVD decoding tasks off the host CPU and placed their graphics chip in control of. 

The first feature the Rage 128 chip boasted as hardware sub-picture acceleration.  During DVD playback, there are times when a sub-picture (compressed bitmap) must be decompressed and outputted.  Such situations include displaying subtitles or menu features.  The Rage 128 was able to handle this relatively simple task of decompression in hardware. 

Secondly, the Rage 128 implemented a feature known as inverse Discrete Cosine Transformation (iDCT) in hardware as well.  In the MPEG-2 decoding process, this corresponds to subdividing the translated image we mentioned in our explanation of HWMC and dealing with the removal of data that isn’t noticeable to the viewer.  Having hardware iDCT support gave the Rage 128 an advantage over the competition that ATI would continue to hold even through the release of their Radeon graphics chip.