Quote:
Originally posted by DaViD Boulet
Actually, very few progressive scan DVD players have scalers.
They all have de-interlacing engines, which is not the same thing.
What makes the SDI path so promising is that the scaling engine...the algorithm that takes you from 480 x 720 pixels to 720 x 1200 or 1080 x 1920 whatever has a direct digital 480x720 source to work from (just like the scaling done in a HTPC).
You're right that a progressive-scan DVD player should be just as good with deinterlacing...but we're not talking about watching a 480P image on the screen here (other wise, all we'd need is a 480P DVD player). We're talking about *scaling* that image to synthesize HD resolutions.
-dave |
Good point. I really should have written "de-interlacers." Although it might be argued that a 480i->480p conversion has also been commonly known as "line-doubling," which is an elementary form of scaling, I will nevertheless concede that most contemporary high-performance displays (except for 42" plasmas) require a true "scaler" for best performance.
[Disclaimer: Yes, I know that 42" plasmas actually _do_ need real scalers to do picture width and height adjustments. To accommodate overscan, they usually end up mapping slightly fewer than 480 lines to the 480 physical lines in the display.]
Nevertheless, the principle stands: do we put the D/A->A/D conversions before the de-interlacer, before the scaler, before the display, or do we dispense with it altogether? While there are a few displays now available that will accept a digital input, most of us still have to deal with analog inputs, at least for the moment.
Of course, CRT displays, being intrinsically analog devices, do not require an A/D conversion. But even systems driving a CRT display _must_ have a D/A conversion somewhere in the path.