delay on conductor camera...suggestions?

[ZachRosing]

I know the issue of delay with LCD panel televisions used for conductor monitors has been brought up before, but my situation is slightly different and I haven't found a clear answer for it. I'm using a cheap Sony Handycam sent through an RF modulator, to a distribution amp and out to two TVs on Channel 3. These are cheap $150 models we got from Walmart.

The issue is sometimes I have no delay between the camera and the monitors (ok, it's a fraction of a second maybe, but it's certainly acceptable) but then other times the delay is much longer...about an entire beat of music off.

So I'm curious why the delay isn't consistent--this part makes no sense to me. I can plug the camera directly into the TV through composite and the delay will be the same as running through the RF modulator, so I suspect its not my camera, RF or amplifier doing something. I understand that my cheapo TV isn't going to have the best A->D conversion--I just don't get why it wouldn't be consistent.

My next question is if anyone has an LCD TV they can personally recommend that has as minimal (and consistent) delay as possible? Based on where we need to place our TVs it's not very practical to try and mount CRT's.


Thanks

Zach

 

[BurkeTheJerk]

Are you noticing the inconsistency within the same song? When you say that it can sometimes be a beat behind, you're using musical terms to describe technology, which doesn't always work. If it's more noticeable in some songs than others, what's different about them? A delay would be more outstanding in a piece with a faster tempo than that with a slower one.

Or the delay could just come and go as it pleases, day by day, week by week, and I'm totally off base

 

[FMEng]

Welcome to the digital age. It's hard to say if the camera, the TV, or both are causing the delay. The modulator and amp do not cause delay. If you can find a TV with a CRT display and an analog camera, (NTSC security camera, or one that records to tape) then you won't have any latency issue. Anything with digital circuitry can introduce latency, which is basically all TVs and cameras made today, although the amount of latency will vary widely.

 

[chausman]

<snip> ...although the amount of latency will vary widely.

And as we've proven, can apparently change. But your saying analog doesn't have those issues? That's nice to know.

 

[DuckJordan]

And as we've proven, can apparently change. But your saying analog doesn't have those issues? That's nice to know.

Thats why the touring broadway shows still have me lug out those 50 lb 15" screens, 250' of analog video cable, and setup that old IR camera...

 

[ZachRosing]

Are you noticing the inconsistency within the same song? When you say that it can sometimes be a beat behind, you're using musical terms to describe technology, which doesn't always work. If it's more noticeable in some songs than others, what's different about them? A delay would be more outstanding in a piece with a faster tempo than that with a slower one.

Or the delay could just come and go as it pleases, day by day, week by week, and I'm totally off base

I realize I'm using very objective terms. I did testing with the camera by flashing a menu up on the screen, looking at the LCD on the camera and the TV at the same time to see how much delay there was and it was nearly instantaneous. Our conductor confirmed this, and then watched himself conducting and confirmed it looked just fine. People in the pit, able to see the conductor and the TV are the ones that notice it being dead on sometimes and very off other times--enough of a delay that it couldn't just be the result of a particular song. It really does seem to come and go, which really makes no sense to me.

It's sounding like it's my TV then. Kind of what I expected. Back to my original question--can anyone suggest an LCD panel or brand they know from experience to be very low latency? For various reasons it's not practical for us to use CRT sets.

 

[DuckJordan]

look for a very high end, gaming monitor, What kind of output is that camera able to put out. What kind of signal are you using from camera to TV? are you using your own cable? or are you sending it through an installed distribution system?

 

[Chris15]

Consider what's happening in an LCD or similar device...
The analog signal comes in and needs to be digitised so it can be sent to the pixels. This process takes time.
Often there are buffers involved and these add more delay and can create a non deterministic element to the delay (a big word to say it's not predictable and not consistent)...

The way analog works with CRTs is that basically the analog video signal has sync signals that directly control the horizontal and vertical beam deflection in the CRT - there's no extra processing involved...

 

[Kingcaffeine]

You'll always end up with delay if your source is analog and your destination is digital. I've used SDI all the way thru the chain before and it's rock solid. So get a decent camera that can output SDI, and use the coax line to an SDI monitor, or a monitor with a DVI input and a mini SDI-DVI box.