Video assist LCD Monitor delay

[davidm]

I'm getting a little tired of vision delays on LCD's used for video assist systems. Typically the delay seems to be around 4- 6 frames. For some reason, everyone on set seems to think this a sound problem.  The people who supply the video assist systems say there's no LCD's video monitors available with low delay - say 1 frame.  When I suggest that there's no problem with CRT's the video assist crew all get grumpy and start mumbling about how heavy they and the director wanting a large monitor (to watch a low res picture from a film camera tap!)

On my current shoot, I purchased a Behringer Shark DSP110 and settled on 0.25 seconds delay on the Comtek feed. This was fine until the director and script  supervisor ended up in the set near the actors. Having the delay was fine looking at the monitor but when they look at the live action......

Does anyone know of low latency LCD video monitors out there being used in video assist systems?

David Madigan

[Guest klingklang]

4-6 frames seems to be a lot. Regular SD LCD-TVs have around 1-3 frames. Maybe it´s because of added delay though HD to SD down-conversion?

[davidm]

I have experienced the delay in HD downconversion but in this case we are shooting film. We have a standard PAL video taps on Panaflex Millenium's

David Madigan

[Philip Perkins]

The downconvert delay is usually about 1-2 frames w/ the HD cameras I see.  This is easily fixed with an cheap used MI market multifx box in the audio line to video assist.  These boxes sound ok, are programmable w/ nameable patches and often can do two separate feeds/fx at once if needed.  They are also usually rack mountable and run on AC.  I don't find this an issue on a stage shoot--on location we usually bag the delay as one more hassle that no one is caring about.  We mostly have to send audio to the camera too, and find that for critical playbacks for Important People they want to play back the HD master and not the SD low-rez video assist anyway.  (So we have to have playback speakers for the DIT to do this....)

Philip Perkins

[wolf]

LCD monitors only have 1 frame or 2 delay. if you are shooting film and there is a 4 frame delay something very weird is going on. Maybe a digital Tx from camera to video ass.?

here a home brew manual for the Shark. the Manufacturers is marginal, the shark itslef sounds as good as the $ 900 Rane though and has a lot more features. We rent a Rane and a Shark.

Audio Delay

SHARK DSP110  a digital delay also called a delay line, the audio delay is set matching the picture delay so that the 2 are in sync on the monitor.

How to save settings

It’s important to leave the DSP110 powered on for several minutes after creating new settings for any function so that they will be saved.  When you power it up again the new settings will be remembered and  re-appear.

To lock the front panel:

Push and hold  the LOW CUT button (till all 5 LEDs above display are on) – the LOW CUT YELLOW LED will blink. Do the reverse to unlock the unit to be reset.

How to increase the speed of UP-DOWN control

This works for any parameter where there is a big numeric difference between minimum and maximum.

Press and hold the UP or DOWN arrow keys, to initiate resetting of numbers .

While holding the UP or DOWN button, press the opposite direction button a couple of times.  Each press makes the numbers increase or decrease at a faster rate. Cool -

TO ADJUST LOW CUT

Press low cut button briefly – LED lights up. Hold the DOWN button till you see OFF in display. To count faster hold DOWN and press UP briefly several times. Range of cut off is 150Hz to Off. For speech use I suggest somewhere between 80 and 120 Hz for a roll off. There is no info on the slope of the filter.

TO TURN OFF GATE

Press GATE button briefly – LED lights up.

Do not press and hold Gate button – if led flashes, gate is in learning mode – that’s would activate it.

You do not want it ON at all!

Press DOWN until you see OFF in display.

To count faster hold DOWN and press UP briefly.

TO MAKE THE GATE WORK

Using the Noise Gate Learn Function

With no program material going through the system ( the input turned down at the previous stage), press and hold GATE button until all parameter lights at the top are lit.

The DSP110 will automatically adjust the gate threshold to suppress any unwanted noise.

monitor what you just did so you know what it sounds like!

TO TURN OFF COMPRESSOR

Press COMPRESSOR once.

You see numbers from 0-100.

For density press and hold DOWN till  you see 0.

To count faster, hold DOWN and press UP briefly often.

Press COMPRESSOR a second time – the m sec light above display comes on. This is the attack time adjustment. It should not matter.

Mechanical Controls

Mic input gain pot in the rear with switchable +48 V phantom power for mic.

Digital headroom adjust pot on front left with 5 vertical LED display – automatically keeps output level the same, it only controls digital headroom for maximum S/N. Do not let the red LED come on ever!

Shark Turnoffs:

It may be RF sensitive so keep it away from Comteks, transmitters, etc. The remote power supply has a transformer in it that radiates a magnetic field. It gets pretty warm, ventilate.

It has good sounding 24-bit A/D and D/A converters and XLRs and phono jacks.

It has an awkward-to-adjust compressor and a noise gate with LEARN Mode useful as a total quieting tool only.

List $ 99.99, Street: $ 80.00 what a deal!  By Behringer engineered in Germany, made in China, poorly written manual, external power supply on 6 ft. cable. Terrific tech help at Behringer USA 1-425-627-0816 X 141 ask for JH; he has some FAQs to email to you ( the useful info is included in this manual). For sales info http://www.behringer.com/DSP110/index.cfm?lang=ENG  can be purchased

from many places such as : http://www.bswusa.com/searchresult.asp?searchType=keyword&searchValue=DSP110

good luck  wolf

[Guest klingklang]

Does anyone know of low latency LCD video monitors out there being used in video assist systems?

David Madigan

Any consumer LCD  out there has "only" 1-2 frames delay  so there is actually a huge market to pick one.

[davidm]

Thanks for the comments, in particular Wolf.  Perhaps my problem is limited to the fact that I always see video assists from the one supplier and I'm very suspect of the mass of wiring and boxes on the video assist Magliner.  I suspect all assembled to a price rather than a specification.  Our monitors are newish Sony LMD 2030's & 2010's.

David Madigan

[Marc Wielage]

I have experienced the delay in HD downconversion but in this case we are shooting film. We have a standard PAL video taps on Panaflex Milleniums...

It shouldn't be more than 2 frames, even including the delay inherent in LCD or Plasma monitors.

If the feed was a standard-def feed from an HD Cam, then it's almost always about 5 frames. That's typical for Evertz, Sony, and several other downconverters.

I agree that it's disconcerting for people to try to watch the live-action with delayed audio, or to try to watch the monitor with live audio. Neither works very well.

--Marc W.

[curleysound]

Not a music guy, but could something like this be helpful?

It's a digital delay stomp box. You could set the appropriate delay, and then place the box at video village. When they want delay, they stomp the box, when they want to watch the live action, they un-stomp.

It's available here: http://www.fullcompass.com/product/335980.html

Tom

[Philip Perkins]

Not a music guy, but could something like this be helpful?

It's a digital delay stomp box. You could set the appropriate delay, and then place the box at video village. When they want delay, they stomp the box, when they want to watch the live action, they un-stomp.

It's available here: http://www.fullcompass.com/product/335980.html

Tom

This might work if the controls allow you to set (and keep) a precise delay that is pretty short by music/guitar standards, and it can memorize that delay setting and hold it when the unit is off.  One advantage of the MI multifx box I use (Alesis QuadraVerb) is it can remember and name many different patches.  I have 1, 2, 3, 4 frame delays for 29.97 and 23.98 programmed and they can be called up instantly, and tweaked if necessary (as w/ Ultimatte etc).

Philip Perkins