Tech Support > Computers & Technology > Video & DVD > component rca to bnc inut on PC monitor?
component rca to bnc inut on PC monitor?
Posted by Another Spellman Revision2 on July 4th, 2003


I want to connect my dvd player to my monitor, via the bnc inputs on the
monitor. Problem is, the dvd player has Pb (blue), Pr (red) and Y (Green
with sync) output. No H or V means that I cannot generate a signal
acceptable by the monitor using the dvd player alone.

So, my idea is to use my old PC to generate a H and V signal. I will connect
a vga to bnc lead to the PC card output and connect the H and V bnc plugs to
the monitor input and the three outputs from the dvd player to the R, G and
B inputs on the monitor. Will this work? I'm thinking that I should set the
monitor to sync on green - correct?

Any idea how to determine what refresh rate I'll need to set my PC card to?
I've assumed that it'll be 60Hz as that is what NTSC runs at. My plan is to
create an mpeg file that is approximately 720 x 480 pixels, then run it in
full screen mode to ensure the H and V output corresponds to that required
by the DVD player.

Is there any risk of damaging my monitor through this procedure?


Posted by John Howells on July 4th, 2003



"Another Spellman Revision2" <customer-serviceDELETEALLTHE CAPS AND SPACES
TOO @sCAPS AND SPACESupanet.com> wrote

Assuming you have correctly described the DVD output this does not stand a
chance!

First, the output you describe from the DVD is component, not RGB, so the
three signals are not the blue, red, and green that a PC monitor expects.
The Y ("green") is luminance (the B&W component) and the other two are
colour difference signals. The page
http://www.gregssandbox.com/gtech/movievideo/comp.htm shows how to create
the Y, Pr (there called R-Y) and Pb (aka B-Y) signal from RGB, and you can
work out similar equations to convert Y, Pr, PB to RGB (in typical text book
style I leave this to the reader!).

Second, the sync has to be *IN* sync! There is little chance that the sync
signal from the PC will be in step with the picture from the DVD player.
Even if the frequency were PRECISELY correct, which it has to be but will
not be, it has to have frame and line pulses at PRECISELY the right moments,
which they will not be. That's why it's called the sync signal, because it
tells the receiver PRECISELY how to synchronize itself to display the
picture properly. The sync source MUST start from the DVD player, however it
may be processed along the way. Any old signal at about the right frequency
just will not do!

If you really want to connect the DVD player to the PC monitor you will have
to get a Component to RBG converter. That will do the "sums" to convert the
signal appropriately and generate the right sync signal. You might be able
to find one at http://www.lektropacks.co.uk or http://www.keene.co.uk/, but
the only ones I could see in a quick look converted component to a "TV" RGB,
which has a composite sync (H and V on one lead), not the separate H and V
sync a PC monitor usually expects.

John Howells



Posted by lash on July 4th, 2003



"Another Spellman Revision2" <customer-serviceDELETEALLTHE CAPS AND SPACES
TOO @sCAPS AND SPACESupanet.com> wrote in message
news:3f05a4bd_1@mk-nntp-2.news.uk.tiscali.com...
Excellent way to get a psychedelic color job on your monitor! PC (VGA)
CRT monitors accept VGA signals (R/G/B component video, + separate H,V sync
as you noticed.) Nearly all DVD-players with component-video output will
only output Y/Pb/Pr (Macrovision license prohibits unprotected RGB
component video output, I believe.)

As for the scan-frequency, a progressive-scan DVD-player's output is
very close to VGA-frequency (33KHz for pscan/NTSC vs 31.5KHz for VGA.) Any
modern multisync SVGA PC monitor will lock-on and properly display the
signal (except for the color.)

....

A handful of specialty (i.e. expensive) PC CRTs can accept Y/Pb/Pr in
addition to the usual RGB VGA input.

No, the video-clock on the DVD-player and the PC must match perfectly. I.e.,
they must be 'source synchronous.' What you're doing is running 2
independent
clocks separately, setting them to nearly identical nominal rates, and
*hoping* they'll just happen to line up. You can try it, but the signals
will drift over time.

probably not... For component Y/Pb/Pr, the signalling level is +/- 0.7vpp
(on the Pb/Pr channels.) RGB VGA is +/- 1.0vpp, I think.

If you're that desperate, you can get a 'transcoder' (RGB -> YPbPr.)
Ask the folks over at www.avsforum.com -- transcoders are often needed
for DVD-players to drive certain digital-projector systems (stupid ones
with only RGB input, instead of Y/Pb/Pr. Or maybe it's the other way
around...)

........

in all honesty, it would be a lot *easier* to just buy a DVD-ROM drive
for your PC. Then install a software (PC) DVD-player and use that
program to watch the DVD on your PC-monitor.



Posted by Another Spellman Revision2 on July 4th, 2003


Many thanks for the reply!

As with most things in my life, I'm most wrong about something when I feel
I'm halfway right.




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