2 cameras, iMac, recording plus live output

My church is interested in purchasing Boinx TV to record our services as well as sending live video and audio throughout the church. We are planning on connecting two firewire cameras using the sonnet echo express card thunderbolt adapter with a firewire pro 800 express card. We would like to capture the sermon slides using the epiphan VGA2USB for PIP. Audio will be from the audio input on the back of the iMac from our soundboard. Will this set up work and if so what version of the iMac should we purchase? Secondly I would like to distribute live video from BoinxTV that I can send through our video distribution system. Can I record and have live output from a second monitor simultaneously using Boinx TV? If so what iMac do I need to purchase?

Thanks for your interest in BoinxTV!

Your setup sounds very good. I recommend to get the fastest iMac with the biggest graphic cards you can get, because video processing means lots of data to be put trough your machine. If you can afford it, I recommend using a MacPro because you want to have multiple camera inputs and record live to disk.

One thing to take in account is, that the digital video processing has a latency of at least 1/3 second, which makes it useless for “live to stage” productions. If you plan to send the video to a big screen inside the church the viewers will recognize the latency for sure.

Sound vs. video delay: If you use the sound input of the iMac, the sound is way ahead of the video you will capture from your cameras. We added an option to delay the sound, so that you can get it back in synch. (See the BoinxTV Preferences -> Devices)

Recording while streaming: BoinxTV is able to display the live output on the secondary monitor output and record live to disk at the same time.

I have same question.I went to mac shop today and saw a 27"iMac that I really liked so much and have made up my mind to buy.Is it going to be efficient ( i mean no lagging etc) with boinxtv?
If so, what card should be use and please can you specify how it should be use so I can follow up properly.I am actually buying this Mac instead of Pc for this boinxtv to use in my church and also for my small home studio.(Final Cut Pro)

Thanks and waiting hear from you.

Just to add to my previous comment,I want to use up to 4 cameras.


Is there any ways I can use component(RGB) cables instead of a fire wire?

iMac: Please have a look at our Example Configurations page here: http://www.boinx.com/boinxtv/exampleconfigurations/ For more than 2 cameras we suggest that you buy an Mac Pro because it is easily extendable, an iMac is not. Currently hardware is able to handle 4 cameras in SD resolution, but hardly in HD resolution.

Component RGB: Please have a look at our Studio Equipment page here: http://www.boinx.com/boinxtv/equipment/ In the Video Input section you find some equipment we tested by ourselves. Have a closer look at the Matrox Products.

Lagging: As already stated in this thread a digital video production setup has always some latency so that you won’t use the result as “live to stage” projection. This is independent from BoinxTV because the latency comes from the digital image processing: The frames has to be digitalized, compressed, send over serial cables, decompressed and displayed. This takes at least 4 to 5 frames.

Thanks.But hopefully SD is gonna come out perfect.

@ Achim.

Is there any fix for this latency issue? I would like to send live videos to a screen also in my church but like you described, it would be odd. Any help will be appreciated.

there really isn’t a fix for the latency issue as it’s just there, as Achim explained. there’s just simply too much processing / compression going on. You’re gonna see it. the only way around it is to split off the feed from the camera & go directly to the projector. Even then there still might be a slight delay because a lot of it depends on the camera too. There’s a reason a broadcast quality cameras costs $10k+ because to work in a true live environment, your gear needs to be built for it & that’s what makes the costs go up. a lot :-/

@Achim do you mean an imac is able to handle 4 sd cameras or a mac pro is able to handle 4 sd cameras? and also, can you upgrade your mac pro graphics card to an unauthorized model that’s not sold in apple stores like the latest tahiti 7000 series line-up. And how much performance gain can you expect than from the current 5770 card?

@adhiravishankar: We are using a MacPro with 3 cameras and an VGA grabber via USB. So, yes, a MacPro can handle 4 SD sources. However, an iMac will have trouble to get the 4 cameras fed into it. We are using FireWire extension cards to have multiple FireWire busses, one for each camera. Otherwise the DV signals on the FireWire Bus will interfere with each other. You can’t install them in an iMac thought.

I can’t comment on the graphics cards you mentioned, because we don’t have them for test driving.