Projecting live video

[estra]

what we want to do is have a live video of the performers projected onto the screen behind the stage. we have a camcorder with firewire and what we want to do is have the camcorder at the back of the audience with a firewire lead running into a laptop networked with another laptop at the front with a projector attached to it. what I was wondering is if there is a way we can stream the live video from the camcorder to the projector at the front with software? is there a way to do this with low latency?

 

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[paulears]

Why do you want to use two laptops? Seems a very longwinded method of doing the job. Much depends on the data rate down the network, but firewire already has some noticable delay, so adding two more conversions into the line won't help that at all, and, the quality will also go down - how much, and if it's acceptable or not will be down to experimentation. I'm guessing that one laptop will be for some kind of effects and processing (more delay) The second is the query? I have to admit that while using 'latency' as an audio term very often, I tend to use 'delay' in video systems - to be honest, I don't really know why?

[dunk_1984]

Surely the simplest way is just to use BNC/RCA/RGB(with converter) to send the signal. Admittedly a little bit more expensive, however will have less delay, and possibly better quality too.

[Pete McCrea]

I'd be certain there'd be a phono video out on the camera. Take a length of Coax video cable and use this straight to the projector. No worries then with the 'Latency' or PC problems. If it doesn't work you know it's one of three things, where as if you using 2 PC's and other stuff then there could well be 5 things to try and trouble shoot plus all the fun of PC's and software.

 

Forget fire wire and use a video cable.

[O Richardson]

Depending on the length of run FOH - Proj, I would consider running data (VGA) and scaling the video image up using an analogue way or kramer unit. More costs involved but a better result.

If the cable run exceeds 40m consider adding into the system a CAT5 system www.smart-e.co.uk do a good one.

[estra]

thanks everyone. I suppose it would probably be easier to do this. I know this has been covered before but is there an easy way to blackout a normal projector (i.e. not one designed specifically for theatres)?

[peternewman]

I know this has been covered before but is there an easy way to blackout a normal projector (i.e. not one designed specifically for theatres)?

Yes, look at one of the previous topics. Sorry but as you say this has been covered before, indeed there is a topic recently active here (this one is mainly DMX blackout, but mentions alternative methods). So have a look through that first, then if you've got any specific questions, ask in that thread or one of the other relevant ones.

[Pete McCrea]

With regard to scaling, it is a feasible option, and as Ollie points out more costly. However if your are scaling up, try to get the scaler to run at a 50Hz output rate, as if it runs at 60Hz and other frequencies it can introduce a strobing effect into the video due the difference in frame rates of the scaled and non scaled signals. Some projectors will not accept a 50Hz data input, and most LCD PC Monitors will not accept a 50Hz data input.

 

Personally if it is a simple set up, I'd run the video at video level, with possibly a line driver if the O/P from the camera is poor, and make sure that you are using good cables, leaving the projector to do the scaling within it's image processing system..