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Conduction Camera Delay

Discussion in 'Multimedia, Projection, and Show Control' started by chadoli1, Nov 10, 2009.

  1. chadoli1

    chadoli1 New Member

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    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
  2. Footer

    Footer Senior Team Senior Team Premium Member

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    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.
  3. chadoli1

    chadoli1 New Member

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    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-
  4. philhaney

    philhaney CBMod CB Mods

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    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.
  5. chadoli1

    chadoli1 New Member

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

    Footer Senior Team Senior Team Premium Member

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    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.
  7. SHARYNF

    SHARYNF Well-Known Member

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    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
    Last edited: Nov 10, 2009
  8. chadoli1

    chadoli1 New Member

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

    philhaney CBMod CB Mods

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

    Like [user]SHARYNF[/user] 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.....
  10. museav

    museav CBMod CB Mods Departed Member

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    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.
  11. FMEng

    FMEng Well-Known Member

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    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.
  12. Chris15

    Chris15 CBMod CB Mods Premium Member

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    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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