Component vs. S-video output
Posted by Jonas A [IP: 130.244.107.130] on August 10, 1999 at 21:20:28
Using Mozilla/4.0 (compatible; MSIE 4.01; Windows 95):
In Reply to: Component vs. S-video output posted by Ken Simmons on July 28, 1999 at 10:51:06:
The component video may be "the most expensive system to implement", but only by the cost of an extra 10bit D/A-converter (Which is implemented anyway in most "better" DVD-players.
As you probably know the image is stored in component video format on the DVD and all TV:s use Component video internally...
Yes, it is better than Y/C, and the reason is simple. Once you combine the separate components of the videosignal you can't separate them completly again.
The more you combine the signal, the more you degrade it when separating the components again!
The signal originates as a RGB-signal in the TV-camera or filmscanner, which immediatly is converted to Component Video (Y-Pr-Pb-format, aka Y-Cr-Cb, aka YUV, where Y is a B/W picture an Pr and Pb is the difference betwen B/W and red resp. blue,) video is usually edited and sometimes stored in this format professionally. This conversion doesn't degrade the signal if the converter is of sufficient quality.
After that the Pr and Pb components are combined to a C-signal (aka Chroma, all Colours together) which gives you Y/C (aka S-video), the next step (and the worst, regarding picture degradation) is to combine the Y and C-signals to composite and in the last step the composite is combined with sound and modulated onto a RF-signal for broadcast.
In the TV the process is reversed.
Most better european TV:s has RGB inputs and many US TV:s has Y-Pr-Pb inputs though.
My TV actually converts the RGB inputs into Y-Pr-Pb for processing and then converts it back to RGB before entering the CRT..
The less conversion stages the better!
DVD is Component Video
S-VHS is Y/C
VHS is also Y/C on the tape, but allways goes through Composite for unknown reason...
LD is composite
TV broadcasts is RF
On the other hand those formats have different limitations in other aspects than vidoesignal, like timeing and most notably resolution. Thats why LD looks much better than VHS and Broadcast TV.