Latency on VT3 using Projection of live video

[crchambers]

We use a VT3 ministry bundle and have some problems with latency during a live service, projecting the live cameras sometimes creates a problem only when using cameras other sources don't have a problem only cameras.

Does anyone have any suggestions, we are building a new church,the current distance is about a 100ft but will be about 300ft which will create even a longer latency.

Would going to SDI throught the whole system kill the latency?

Would genlock help or hurt?

Is there a better way to get the signal from VT3 to the projectors without latency?

Please feel free to respond....

We are having a big meeting on wednesday the 15th of june 2004 on our new property to discuss A/V, lighting and audio.

Any help you can shed on the matter before would greatly be appreciated.


Thanks..... Charles Chambers.... Assitant TD

[Jim_C]

http://vbulletin.newtek.com/showthread.php?s=&threadid=22942&highlight=projector

http://vbulletin.newtek.com/showthread.php?s=&threadid=19662&highlight=delay+projector

http://vbulletin.newtek.com/showthread.php?s=&threadid=15731&highlight=delay+projector

http://vbulletin.newtek.com/showthread.php?s=&threadid=1638&highlight=delay+projector

[PIZAZZ]

Latency. What fun huh? First off let me state that we do a ton of live switching in the field and also have setup quite a few churches with VT and projection systems. We have worked with the latency issue in many different setups and the following is what we have come up with.


Originally posted by crchambers
Does anyone have any suggestions, we are building a new church,the current distance is about a 100ft but will be about 300ft which will create even a longer latency.
Actually the longer or further distance from the screen the less of the latency will be perceived. Sound travels slower than light so the further back you are from the screen then the less latency you will see.

Would going to SDI throught the whole system kill the latency?
Would genlock help or hurt?
By genlocking all of your cameras then you will definitely minimize the work that VT3 has to do. With all of the cameras synced together you are presenting to the VT a unified signal instead of several different ones all having to be resynced by the VT. We have one install that has 4 JVC studio config cameras with CCUs and the latency there is 3 frames on the screen. I can see it but I have only had one other person in the congregation ask me about it. They were sitting about 5 feet from the preacher and looking at the screen over his shoulder. I told him it was rude not to look at the preacher if he was that close anyway. I haven't heard a word since.... LOL


Is there a better way to get the signal from VT3 to the projectors without latency?
The format of the signal would not really make that much of a difference. For the best quality signal then yes definitely go with the SDI format.

Different manufacturers of projectors definitely make a difference. If at all possible try to rent the same projector as you are planning to buy and do a test run before commiting. I have done that for several churches and that has made all the difference in the world. One they can see the brightness and detail in the new projector and 2 they can justify the difference in cost especially if you have their previous projector still hooked up also. One local church went from a 2000 lumen to a 5200 lumen with no problems after the demo one Sunday morning.

Hope this helps you out some. Let me know if I can be of further service.

[jcupp]

Keep in mind anything that processes the video digitally will probably add at least a frame of delay. So beware line doublers, video scalers and the like.

-Jeff
Digital Arts

[BrentYoung]

We use our Toaster to feed two live overflow rooms. We simply added a audio delay to sync with the rooms and everything is peachy. Behringer makes a box that looks like a direct box but has a varriable delay that works great.

B

[vanguard]

We fought this for a long time.

I agree: Sync the cameras, it definately eases the VT.

Also be aware that some LCD and DLP projectors add 3-7 frames of delay in their internal A to D converters.

When you add that to the VTs 3-4 frame (my estimate) delay, you're reaching to objectionable delay times.

We went back to CRT/Telaria based projectors for live VT events to prevent as much delay as possible.

Any time you go from digital to Analog or back you are adding delay for the processing. We first saw this on DVCPro machines in analog linear edit stations.

Interesting side note: D-2 VTRs have no delay in Analog signals..... Because they can pre-read the data real time it reads the data ahead of the processing delay so the signal exits the machine "on time"".....

And you can do a linear dissolve without the 3rd. machine....

I'm sorry I got off track there.

[RandyM]

I'm just getting into projection in the next couple of weeks. I understand what you all are saying. My question is how to sync the cameras before they hit the SX8. ?

We are using 3 x Sony VX2000 prosumer cameras. Svideo out

[hartley]

The syncing of the cameras as referred to here is Genlocking them with a blackburst or other sync source. To do this you have to have the inputs on your cameras/CCUs. The VX2000 does not have this capability, as far as I know.

A side note we actually removed the genlock (GASP...I know) because we found the delay to nearly perfectly match our auditoriums delay loudspeakers without having things genlocked. It was actually awkward for attendees to have less of a delay. This goes back to the previous comment on how the latency will be perceived.

Hartley