latency frame drop in IMAG

[timcates]

Hey guys - setting up a new system and can't seem to get the delay down as far as I would like....here's the rig:

2 Sony NX-5 cameras - connecting via HD-SDI

Panasonic HMX-100 switcher -
Multiview out via DVI - inputs via HDMI (cable converts) to a Sony 42" TV -

Program out via DVI to a TVOne RGBHV converter for the projectors (CHristie LX-1500s)

Main SDI out to an AJA KiPro recorder.

the lag that I see is present on the preview monitor, and is worse when I set things up to run at 1080i/60 than when I set things up at 720/60.....seems odd to me.....our screens are in view of the choir/band and it can be distracting to them if the camera is focused on the conductor.... (we're seeing about 1/4 of a second of delay or a 16th note at 60bpm.).......

Any ideas? Is the multiview out to a consumer TV the culprit? I've tried an AJA SDI to HDMI converter instead for the multi out and not noticed any improvement......

Thanks in advance for any ideas!

Tim Cates
Highland Baptist Church
Waco, TX

[petereit]

1. You should be running a tri-level sync generator to your switcher and cameras. This will shave as much as 3 frames off your delay.
   
2. Don't run your 42" TV off the multiviewer output. The multiviewer itself is probably adding 3 or 4 frames of delay. Run straight from PGM out. There will still be 1 to 5 frames of delay from your TV's internal scaler (depending on its quality), and that's the best you'll ever get.
   
3. Train your band/choir to only look directly at the conductor.

[timcates]

Thanks - the AJA GEN10 looks like a good match for this........BUT, since the Sony cams don't have genlock......is there a black box that can add this capability to the cameras? Is there a better way (that doesn't involve a new camera...)?

[petereit]

Originally Posted by timcates

Thanks - the AJA GEN10 looks like a good match for this........BUT, since the Sony cams don't have genlock......is there a black box that can add this capability to the cameras? Is there a better way (that doesn't involve a new camera...)?

Ooh. Nope.

[tdangelo]

Tim,

Any time your switcher or production system converts a signal from one flavor to another, scales a signal from one resolution to another, or frame syncs a non-genlockable signal delay is incurred.

With the exception of the input to your Ki Pro, it seems like every other input and output is being converted and therefore creating delay.

• Sony HXRNX5U cameras into switcher (cameras are non-genlockable, switcher will frame sync inputs)
• Panasonic Multiviewer DVI signal converted to HDMI to go into multi-viewer Sony screen
• Sony 42" TV may be scaling the DVI-to-HDMI input signal if its at a resolution not native to the screen
• DVI to TVOne RGBHV converter for the projectors
• Main SDI out to an AJA KiPro recorder (delay only if then coming out of Ki Pro to ???)

To avoid frame you must get rid of some/all of these conversions. Regarding the cameras, yes replacing them with gen-lockable models will help. Until then, try genlocking the switcher to one of camera signals (page 28 of the switcher manual describes how to do this). Are the camera cables the same length? If yes to these two questions you may be able to rid yourself of the camera delay if the switcher allows you to turn off the internal frame syncs.

[Gracetech]

Is this only happening in your preview monitor? If so then it's possible that you have a monitor with just an abnormal latency. I have a couple of monitors at home and one has around 8ms of latency which is what i would expect. The other although is says in it's specifications is 6ms is actually 44ms(yeah i tested it). I had to go with the 8ms monitor because the 44ms of latency is just unusable.

Also as others have mentioned you will accumulate latency on conversions and processing but that should only come out to 5-8ms through your system.

Try a different monitor if you have one. If that doesn't sort it out then you may be stuck.

We have the NX5's running HD-SDI back to our HS50N and our Multi-Viewer output is pretty tight. Now our Campus feed is slow to me and i adjusted the audio to compensate for it. As bad as i though it was most people just couldn't see it even though i was pointing it out.

crt

[timcates]

thanks all for the info and advice....much appreciated!

Gracetech, I assume that you're also feeding computer into the switcher for overlays and still seeing things pretty tight.....what res are your NX5s set to? What about the computer input resolution and settings? As far as the Sony TV....I'm seeing the same delay in the preview that I see on the FOH screens.....I'll try a straight DVI monitor that I've got laying around later today and report back....

TC

[Gracetech]

Well I'm running 1080i out of the cameras and into the switcher. I don't do overlays with CG just switch back and forth between ProPresenter and Cameras. We are running 1024X768 on the CG side but that will change soon as i get a new computer. Our IMac just can't hang with high resolution graphics.

I was thinking, you may just want to bypass the switcher and plug one of your cameras straight into the hdmi converter and see if it is still laggy.

crt

[waynehoskins]

Here's a for-what-it's-worth.

Our system is entirely analog composite. Now we rarely run IMAG, but when we do there's about a 3-4 frame delay -- or at least there was with the old projectors that we recently replaced; I haven't tested the new ones.

This delay is entirely within the projectors themselves, since our entire chain through that is all broadcast gear that's properly synchronized, feeding 525 lines to the projectors.

The point of all that is that even a single conversion (with a cheap built-in converter) in the projectors can introduce quite a bit of delay. Our situation is best-case for analog IMAG (projectors aside). Throw in several conversions and resyncs upstream of that, and you're just asking for trouble.