# Conduction Camera Delay



## chadoli1 (Nov 10, 2009)

What is the solution to Conduction Camera Delay?

When we added LCD Flat Screens to replace our CRTs the signal had very slight (.25 second) Delay- Which was not acceptable to the opera conductor and singers.

I have heard rumors of Plasma working better, and RF-modulators but what is the REAL solution to eliminate 100% delay of a live Video Fee when using a Flat Panel Monitor?

chad


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## Footer (Nov 10, 2009)

I assume your not getting this delay using a CRT? Odds are there is some type of image correction turned on in your monitor. Find that setting and turn it off.


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## chadoli1 (Nov 10, 2009)

You are correct- the CRT has No Delay- we spoke with the monitor manufacturer and turned off all delay function, and still had the delay- so we returned the flat Screens-


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## philhaney (Nov 10, 2009)

chadoli1 said:


> You are correct- the CRT has No Delay- we spoke with the monitor manufacturer and turned off all delay function, and still had the delay- so we returned the flat Screens-



CRT monitors are analog and flat screen monitors are digital. 

Your 0.25 second delay was a result of the flat screen having to convert the analog feed to digital and load it into the monitor's video memory.


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## chadoli1 (Nov 10, 2009)

So the real question is how do I use a Flat Screen TV for a live video feed with no delay?


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## Footer (Nov 10, 2009)

The better the hardware the less lag there will be. A 100 dollar LCD from wal-mart is not going to have good A-D converters in it.


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## SHARYNF (Nov 10, 2009)

while the quality of the a/d may vary, I think you are going to find that there is no way to completely eliminate the delay. Basically the monitor needs to get the full frame in and then convert it to digital and then send it to the display,
Analog monitor starts to paint the screen as soon as the signal arrives. 
You will see some articles about measuring and zero delay displays but these are NOT converting composite video to a digital display

http://www.behardware.com/articles/632-1/lcd-retard-affichage-crt-oui.html

Sharyn


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## chadoli1 (Nov 10, 2009)

So what if I use an HD Camera going into an HD Monitor? Will there be a delay?


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## philhaney (Nov 10, 2009)

chadoli1 said:


> So what if I use an HD Camera going into an HD Monitor? Will there be a delay?



If the signal and monitor are analog, no. If they are digital, yes.

Like SHARYNF said in a previous post, "_the monitor needs to get the full frame in and then convert it to digital and then send it to the display_."

Even if they are both digital so no conversion is required, the digital monitor needs to load a full frame into video memory before it can display it on the screen. An analog monitor "draws" the lines (or image) on the screen as they come in. At 29.97 frames per second (standard NTSC) there will be a delay. HD comes in several frame rates, but whether interlaced or progressive, the "load it into memory" delay factor will still be there.....


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## museav (Nov 11, 2009)

There is also the issue of scaling, unless your source and display match in resolution the display is having to 'map' whatever resolution it is receiving to the native resolution of the display. When a display is having to deal with all three factors (A/D, buffering and scaling) the resulting latency can often be noticeable.


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## FMEng (Nov 22, 2009)

chadoli1 said:


> So what if I use an HD Camera going into an HD Monitor? Will there be a delay?



Most likely, yes. An HD camera has digital processing inside, just like the LCD monitors. Anything digital, be it for video or audio, has latency. You might be able to find latency specs for cameras, monitors, and other digital video devices. Some are obviously faster than others.

Back to the original problem, you might find that more expensive monitors, with a faster refresh rate, may have less latency. Refresh rates for LCDs seem to vary from 60 Hz to 240 Hz these days. Unless you can find latency specs, get several models and compare them.


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## Chris15 (Nov 24, 2009)

There is no way of avoiding latency in a digital system. You have to use analog for things like conductor cameras. You also need to avoid any processing along the way apart from something like a distribution amp.


So basically the answer to the original question, _So the real question is how do I use a Flat Screen TV for a live video feed with no delay_ is that you can't. You may be able to reduce the latency to an acceptable level but that's just one of those fun bonuses attached to using digital...


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