Video Asylum

Posted by Joe Murphy Jr (A) on March 11, 2005 at 22:40:50

In Reply to: If a DVD-R has only s-video in, is component out likely to be better than s-video? posted by John C. - Aussie on March 9, 2005 at 15:01:21:

you may not be able to see much of a difference on your display. More to the point, how much of a difference you will see on the displayed output will be directly related to the quality of all the processing and converting that's taking place in the DVD recorder and the display itself -- in addition to the quality of the original source that you will be using.

Here's the simple version:

The analog S-video (Y/C) input is A/Ded and separated into color difference signals (YCbCr). What's recorded on the DVD is YCbCr 4:2:0 and is output by the MPEG decoder as YCbCr 4:2:2 digital video. Before the analog outputs, it's D/Aed and is available as component (YPbPr), S-video (Y/C) and composite (C).

Since the YPbPr output is the analog version of the YCbCr format recorded on the disc, it is closest to the original source. To use the S-video output, a downconversion/combining process must take place to get that Y/C output. That's not all too horrible, but when you consider that the display is going to take that signal, do another conversion in order to get a signal that it can process (YCbCr, YPbPr or RGB) and then do some additional processing of its own before it's even displayed... Well, any extra processing and conversions are seldom a good thing.