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[Rich Gouette]

How long can you effectively run a DVD's composite video output?

Application: I'd like to place a small component-style DVD player in the soundbooth, and pipe it up to our overhead projection unit(50-60 feet or so total length).

Thoughts?
Thanks all..
Rich

[Bob Payne]

Well, we have a DVD/VCR/video camera setup where we run the three separate components through a Kramer 5x4 video interval switcher, then 75 feet through RG6 quad shielded cabling to the FOH projector onto a 6'x8' screen.  We also have a 100' section of RG6Q coming back from a video camera from the FOH to the switcher which also seems to work acceptably.

No matter what you do, ordinary composite video is not going to look good on a screen of that size if viewed up close, but this particular setup seems to provide quite acceptable images considering the inherent limitations of a composite video signal.  Composite video can't begin to compare in quality to our RGBHV signaling sourced from our projection computer, but it seems just fine for occasional DVD/VCR video use.

Whatever you do, if you want to run video signals very far, use the lowest loss cabling that you can find (this usually translates to larger diameter cabling) with decent shielding.  RG6Q seems to work for distances up to 100 feet for us.

Bob Payne

[Greg Hertfelder]

Running 50-60 feet of coax shouldn't create too much degradation, as Bob described. However, instead of running one strand of composite cable, consider doubling the coax count and run the signal Y/C (S-video), by using a S-video-to-BNC break-out adapter on each end. Running the circuit Y/C will keep the monochrome and color signals seperate for the long cable run, and provide stronger color purity, and eliminate the anomaly called "chroma crawl" present in composite circuitry.

For the future, consider buying a combination scaler/switcher(seamless switcher), such as made by Analog Way, Extron, or Kramer. Seamless switchers  convert NTSC interlaced video to progressive scan, and sends the video to the projector in the RGBHV (computer) domain. It makes switching between sources a lot easier for the AV operator, as it can be located next to the DVD player & computer.

[Rich Gouette]

Ok, thanks fellas.
I should also have mentioned this:
The PC in the booth, currently sends a S-video signal out to said projector.(via a A/V card)
Would it be smarter to simply put the DVD player on a switch with the PC, and simply switch the S-Video signal going up to the Projector?
Is this doable as well? (would save me from running another cable)
Cheers!
Rich

[Brad Weber]

Once the signal is composite you've introduced all the related issues, converting to S-Video (or more accurately Y/C) can't undo what's been done.  You also have to consider that Y/C signals are normally lower in level, 0.7V P-P for Luma and 0.3V P-P for Chroma are typical versus 1V P-P for composite video, so line losses from the cable can have a greater impact on Y/C signals than on composite signals.

Most DVDs will have composite video, S-Video and component video outputs.  You say that you already have S-Video run to the projector from the computer and are apparently satisfied with the picture quality you're getting, so using the S-Video output of the DVD and a local S-Video switcher should both provide a better image and save running another cable versus running the DVD separately as composite video.

The Extron MSW 4SV (S-Video only) or SW4 SVA (S-Video and audio), the FSR PN-2102S or the Kramer 4x1S (S-Video only) or VS-61YC (S-Video and audio) are some small switchers that might fit the purpose.

Of course, from an image quality perspective an even better approach would probably be to use the existing Y/C cabling for the DVD and to add new RGBHV cabling from the computer VGA output.

[Aaron McQueen]

Since you are running cables, you should use a dual monitor set up for the PC and projector.  Get a video card that has dual outputs, use one for your monitor at the PC and the other for you projector.  Run a VGA cable from your PC to your projector.  The quality of the image will be considerably better than the s-video output you are using now.  Of course this does not cover the DVD player to projector problem.

We do the following.  We have a dual vga card, one going to the PC monitor and one going to the projector (in windows xp the two screens can have different resolutions, and are totally independent of each other).  For the DVD we run s-video to a video capture card in the PC.  We use EasyWorship software for words that supports the capture card.  In EasyWorship you can preview the capture card, cue the DVD and send it to the projector when ready.  We also ran a serial cable from the PC to projector.  I wrote a few .bat files to control the projector's ON, OFF, and SHUTTER functions, and assigned them icons, basically providing control of projector from the PC.  It works very well and is easy to use, never a blue screen or PLAY text on the screen, but without the expense of a true switcher solution.

[Jarrad Semmens]

I regularly run C-Video over RG58/59 cable up to 100meters plus. generally require some kind of ampliphier but have run without it. Composite video can run well over long distance with good cabling. S-Video on the other hand has a very limited distance. In fact most of the time the difference between S-Video and C-Video is negligable.

If you have any other questions I can dig up some technical specs of the various formats.

Jarrad

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