So where does PureVideo on the 7800GTX come in?

NVIDIA’s PureVideo de-interlacing on the GeForce 6 series and GeForce 7800GTX use othe same algorithm: a region-based motion-adaptive de-interlacing strategy and it turns out that it’s actually very good. Essentially what is done is that for each pixel in the video, a determination is made if the region contains motion. This is done by looking at a region of adjacent pixels over a few historical fields (the region size and number of historical fields are not disclosed by NVIDIA but it would not be hard to reverse-engineer those numbers with custom test patterns). If the region of pixels do not contain motion, then it is possible to display both fields without losing data. Therefore, only regions that contain motion undergo the “bob” type deinterlacing.

In standard definition, PureVideo holds its own against “gold standard” products for standard definition interlaced sources such as the Faroudja DCDi and is even superior to DScaler (but not the scaling portion). When it comes to HD content however, HDTVs with Faroudja processing and HTPCs with GeForce 6 series products are virtually identical as they both rely on using only one field at any given time.

The key point is that the 7800GTX has sufficient horsepower to apply those same PureVideo calculations to 1080i HD video. This means that the 7800GTX decodes 1920x1080i at 60 fields per second to 1920x1080p at 60 frames per second while selectively preserving detail in areas that are not in motion.

The Competition

NVIDIA is not the first manufacturer with region-based motion-adaptive HD deinterlacing, but NVIDIA is joining the company of only a select few. You’ll find this technology in Gennum’s VXP that powers a $15,000 Marantz DLP front projector or Christie Digital’s professional grade projectors. The impressive feat is that the 7800GTX actually brings this down to your desktop and the $600 for the 7800GTX suddenly doesn’t look all too expensive. (Of course, VXP does other stuff like diagonal filtering and noise-reduction which NVIDIA does not).

Note that although NVIDIA advertises their PureVideo in the 7800GTX as being a “Spatial-Temporal Per-Pixel Deinterlacing,” but we are electing to use the term “region-based motion-adaptive de-interlacing” because it’s really per-pixel-spatial and region-based-temporal de-interlacing. Although each pixel is evaluated independently, determination of whether there is motion or not happens at a larger scale rather than the individual pixel level. Still, NVIDIA should still be very proud of their achievement – they have a HD deinterlacing solution better than the former gold standard Faroudja, and are in the company of peers such as Gennum.

GeForce 6-class PureVideo is an excellent solution for high-quality DVD playback and whether you’re building an HTPC or a gamer simply interested in high-quality DVD playback, we have no hesitations about recommending a $20 investment in the NVIDIA DVD Decoder.