Video Delay Issues

[RZUMBA]

I using a camcorder with std rca video cable (35ft) (with coupler) to show live video on two 50" televisions behind the stage. There is about a 1/2 second delay between the screens and what is happening on stage. What causes this? How can it be corrected? Shorter cable? S-Video Cable?

 

[tyler.martin]

your camera probably does not output a strong enough signal to run 35ft with no signal degredation. Try using a video signal amp right at the start of the cable. Svideo might make a difference in the quality of the picture, but if the camera has a weak output, there still might be a delay.

Also, check your camera to see if it has a 24 frame per second setting. It should be on 30fps.

Let us know if this works

 

[RZUMBA]

Thank You I will give this a try!!

 

[mrb]

your cable isnt going to give you 1/2 second of delay. Its probably the camcorder taking its time to process the image and send it out the video out. Try a regular CCTV camera.

 

[SHARYNF]

What Camcorder are you using? some of the recent HD consumer cams have to down res and process the output and give priority to compressing the image for storage on the camcorder. 15 frames delay seems excessive but certainly is possible. Note the if you are using any switcher it can introduce a 1 or two frame delay and many of the DLP projectors also introduce a 1 or 2 frame delay
Cable loss will degrade the quality of the signal but will NOT add a delay
Sharyn

 

[museav]

I moved this thread to the more appropriate area.

I have to agree with the last couple of posts, it is not the cable and a DA or buffer amp will not reduce any latency. Sharyn probably nailed part of it, on many camcorders the composite video output is down processed and that introduces some latency. Another aspect may be the displays themselves, if they are digital displays (LCD, plasma or DLP) then they are having to process and scale the composite video signal from the camcorder, thus introducing additional latency. And as Sharyn also noted, any intermediate switching or processing could introduce additional latency. Simply an inherent part of using digital devices with an analog signal, there are often multiple A/D and D/A conversions and some signal/format processing involved and those normally introduce some latency.

 

[fredthe]

I've seen some displays add a lot of delay, but as Sharyn said, it may be the camera...

As a quick test, try plugging the camera into an old-fashioned (CRT) TV (if you can find one...) and see if the delay is present there. That will tell you which end is your problem.

If you are otherwise seeing a good image, then your cable is not a problem.

One additional thought... how are you splitting the signal to the two screens?

-Fred

 

[RZUMBA]

Thank You All! Here is some more specific Info. I am using a Sony DCR-DVD300 Camcorder. I have the option to change the setting to Sports, will this give me a faster frame/sec rate? Since this is done inside in low light I might trying setting to Night Shot. Would this increase the frame/sec rate?

Also to answer how am I spotiing to two screens - I am using a 1-in 4-out video amp.

My set-up looks like this

Camera to A/V Mixer (Numark AVM01)
Audio out of Mixer to Yamaha EMX 640 - out of EMX 640 to Speakers/Sub
Video Out of Mixer to video amp splitter
Video Amp Splitter to two 50" LG Screens

Picture is Adequate - Just having a Video Delay Issue

When using the Camera, it is just on the "On Position" Not doing any recording.

The Setting During High EnergyAerobic Class is

1500 Aerobic Floor Approx 45ft wide by 33ft deep
16ft Stage w/ LED Lighting

Lights out except for an emergency light in the back. Lighting generated by stage lighting.

As class follows instructor it is important (if possible to eliminate delay)
shown on the screens.

Last question, is it possible to delay the audio to sync up to the video?












Cables basic RCA Cables

 

[SHARYNF]

Changing from normal to sports mode is not likely to help, the issue is probably in the camcorder conversion to Composite video and the mixer and the display.
Try to connect the camcorder directly to the display and see how that changes the delay. The Numark mixer could very likely be addiing a significant delay.

Your display MIGHT very well normally delay the audio for its processing but you are not able to use that since you are bypassing the display audio.
try to connect the video camera to a standard tv. this way you can begin to look at the delay added vie the camcorder, the mixer and the display

If you look on ebay there are some PEAVEY IDL 655's for sale starting at about 50 dollars, these could be used to delay the audio for you by setting the dip switches
here is the link for the manual

http://www.peavey.com/assets/literature/manuals/80300584.pdf

You can use the traditional clapper method where you align the image of the clapper closing with the audio hit.

Sharyn

 

[RZUMBA]

Thanks Sharynf. I will try some direct connections to see if the delay is still present. I may try a different camera (CCTV) first. Then I will go the Peavey option to delay the audio. Thanks again!

 

[SHARYNF]

Thanks Sharynf. I will try some direct connections to see if the delay is still present. I may try a different camera (CCTV) first. Then I will go the Peavey option to delay the video. Thanks again!

The Peavey option is to DELAY THE AUDIO, your video is already delayed based on what you are saying here.

I would GUESS that most of your delay is from the mixer be interested to see what you find out
Standard video runs at 29.97 Frames per second so roughly 30 frames per second, or 15 frames for half a second delay
I would GUESS that you are closer to 7 frames delay with 1-2 in the camera 2-3 in the mixer and 1-2 in the display
2 frames or so is not noticable under most conditions and even 3

Sharyn

 

[Chris15]

This is why digital anything is a really bad idea for something like a conductor relay camera...

I'd try camera straight into display and see what the latency is there and then add in extra components and see where the main culprit is...

Yes you could delay the audio, but that won't fix the issue of the half of the class watching the instructor direct being out of sync with those watching on the displays...

 

[SHARYNF]

I could depend on the application, IF the class watching is remote from the live performance and just needs to see audio and video in sync then a delay will work, IF on the other hand the class needs to be doing something where timing is very critical and they need to rely on the monitor to say for instance PLAY instruments in sync with the live performance then things get a bit more critical

Our eyes are very very good at picking up the out of sync between sound and lips for instance
Sharyn

 

[RZUMBA]

I hooked up camera directly to the Video Distribution Amp (By passed Mixer) which splits signal to both screens and still experience same delay. Since I need to split the signal to both screens, I did not try direct to displays. Given the fact that I need to split the signal is there a recommendation of cameras that offer a faster frame/sec or do not need to process like a video camera. Will a CCTV Camera work better? I don't have one, but I also don't want to buy one just to see if it would work.

I guess I need to try direct to the displays, if it is acceptable, or at least improved, I could possible get a cable with two males at one end and connect one cable to both displays.?.?.?

By the way, delaying the audio is not an option since the audience is live and the instructor on stage needs to be in sync with the screens.

Thanks to everyone for their input - Problem is, I have a show this weekend and it sounds as though there is no quick solution or at least not an affordable one.

 

[fredthe]

I'd say it's 50/50 chance between the camera and the display being the problem. See if you can find a CRT TV to connect the camera to, to see if it's the source of the delay. If it's the displays causing the problem, replacing the camera won't help.

And no, you can't just use a Y-cable to drive both displays, and I doubt they have a loop through connection.

-Fred

 

[SHARYNF]

Interesting that the mixer is not the problem. See if you can borrow a standard Camcorder, Personally I like the sony models, as they typically don't need to use the remote to turn off the display mode of info on the display feed. Leave the tape out, use the composite video as the connection (you might need to find the av cable from the camcorder sony uses a 3 connection cable.

Try to re set the displays to standard video resolution. It is Possible that the display is taking a few frames to upscale the image.

A few frames of delay is probably the best you are going to get. what is the application where the display needs to be exactly in sync with the audio? If it is just talking then it is annoying but workable (a lot of tv cable/Sat feeds get out of sync) Is they any chance that the connection to the display is VIA a RF link usiing a TV channel. I have seen this where a RF conversion is used to feed remote display tv;s and they you are absolutely going to get a delay that is not going to be able to be eliminated unless you go direct to the display.

Sharyn

Sharyn

 

[RZUMBA]

Thanks again to fredthe & sharynf. To answer the question, "what is the application" The live person on stage (dancing) needs to be in-sync with the live video on the screens. People in the audience are following the instructor on stage. As far as the audio is concerned, it is a separate matter.

I will try to find a CRT TV as well as another Sony Camcorder. I had an old one, but I am hard pressed to know where it may be.

As i mentioned earlier, I am using a Sony, but is is a DCR-DVD Camera.