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Multiple tv outs

does anybody know of a cheap possibility to use every output of your graphics card as a composite video signal? has anybody worked with those cheap hd15 vga to composite video adapters? can you use more than one of them at a time? do they produce underscan or overscan video?

those cheap hd15 vga to composite video adapters
what devices do you have in mind?

its actually possible to wire an adaptor from hd15 vga plug to a SCART plug. as long as the tv understands RGB on its SCART input (most tvs will do)

the tv will not be happy with standard xga resolutions, but by using powerstrip it should be possible to force the graphic card to output signals with interlacing and PAL or NTSC resolutions and framerates. i think home cinema enthusiasts do this all the time. inhabitants of NTSC countries even might have a windows standard monitor type already configured.

apart from that you can generate 3 monochrome luninance signals from one rgb output, any color monitor should be able to display this luminance signal as a greyscale image (due to some breathtaking oldschool backwards compatibility engineering from the 60ties). but you already talked about color from what i remember.

those cheap hd15 vga to composite video adapters
what devices do you have in mind?

For instances the
Matrox
TV-output adapter cable (HD15 to composite video and S-video)
Part #: CAB-HD15-TVF

"Allows a composite video and/or an S-video output device (typically a TV or video recorder) to connect to an HD-15 connector. Each output device (composite video or S-video) receives the same video signal in different formats.

… as seen on their technical upgrades page:
http://www.matrox.com/mga/workstation/3dws/products/upgrades.cfm

Something similar exists for apple dvi-outputs.

its actually possible to wire an adaptor from hd15 vga plug to a SCART plug.
as long as the tv understands RGB on its SCART input (most tvs will do)

hm … I have do bridge long distances with coaxial cable, and I have to multiply the signal. I need to supply 40-50 TV sets with a video signal.

Re: CAB-HD15-TVF

i presume this cable will just instruct the driver to output composite signals on one of the pins usually used for red, green or blue.
so you might be able to use a hd15 to 5xBNC cable plus some BNC to cynch adapter to do similar things.
so for underscan and overscan things you need to find a solution in the driver. powerstrip most probably would also do the trick.

hm … I have do bridge long distances with coaxial cable, and I have to
multiply the signal. I need to supply 40-50 TV sets with a video signal.

ok. so if you do not want to use an rf-sender to transmit the signal over the air, composite signals might be more convenient.
i think a composite video distribution amp shouldnt be too expensive. there are even cheaper ones for home use…

i came across the followin card Xentera GT 8: 4 RADEON 9000 chips on a board sharing 256MB and plugged in over one PCI (!) slot. dont expect shaders to work (DirectX8.1) and dont expect fast loading of textures (or full motion video).

it might do some tricks for slide shows or simple graphics, and you might be able to put several of these in one standard box…

has anybody out there used this for vvvv?

We stumbled over the german distributor of the Colorgraphics Cards before. Funny name. DIMESO

They also offer the quad version of the card for rent, cheap.

okay. I had contact with dimeso and checked out their xentera gt 8 / 4. for my purpose they would certainly be fine. unfortunately they do not have a pool for cards to rent.

in which way is a composite signal different from a black and white signal? would it theoretically be possible to write a shader, that combines the rgb values into one signal, that could be routed to one of the hd 15 pins? a composite signal is just one signal. or is it a signal that is spilt into different frequencies, that run through the same cable? or does one channel of the rgb signal just have not a frequenncy that is high enough to contain the color information. could this be achieved with powerstrip, maybe? questions, questions … i still didnt really understand what these hd15 to comp video adapters do. you said they tell the driver to send a composite signal out of one pin. shoulnt it then be possible to send a composite signal out of each pin?


i dug into the format of a composite video signal. i now understad, that it basically consits of two parts, the luminance and the crominace. the luminance is - as you said - a pretty straight forward analog represantation of what is going to be seen on the screen. the chrominance, though is encoded at 3.18 MHz, and the color signal is then being modulated onto the luminance signal. i assume, that 3.18 MHz is actually a frfequency too high for a componet hd15 output.
but the graphics card seems to be able to generate such a signal … maybe there is still a possibibility … ?