Simultaneous video from multiple cameras

[bhorowit]

Hi,

I am wondering if it will be possible to simultaneously acquire video from multiple cameras.

Let me first briefly describe our hardware set-up. We are planning to have a single PC with two firewire PCI cards. Each of these cards will be attached to three Imaging Source DFG/1394-1s. Each DFG/1394-1 will be attached to two analog grayscale cameras. So, the PC will be attached to a total of 12 cameras.

We are aware of the firewire and PCI bus throughput limitations; this post concerns only IC Imaging Control.

I was reading the documentation for the C++ class library, which we would like to use, at:
http://www.imagingcontrol.com/ic/docs/html/class/ref/class/grabber/c_grabber_opendev.htm
This page states that the Grabber :: openDev method closes any already-open device before opening the new device. Does this mean that I will only be able to acquire a video stream from one camera at any one time? Or does it only mean that I need multiple grabber objects, and with each grabber object I open distinct devices?

If indeed I will be able to acquire video streams from two or more cameras simulataneously, I have two additional questions:
1. Is it possible to simultaneously acquire two video streams from the two analog cameras connected to the same DFG/1394-1?
2. Is it possible to simulatenously acquire two video streams from different DFG/1394-1s?

Thanks in advance for your help! :) :) :)
Ben Horowitz, Ph.D.

[Stefan Geissler]

Hello Ben,

You are right, one Grabber object can only handle one video capture device. Therefore your application needs more than one Grabber objects. You may put them in an array:


DShowLib::Grabber m_cGrabber[6];


You can access more than one DFG/1394-1 simultaneously and display the live videos. As you mentioned correctly, the PCI bus and FireWire bus will set the limits.
Each DFG/1394-1 can deliver only one video stream regardless how much cameras are connected to the DFG/1394-1. The DFG/1394-1 uses a multiplexer to switch between the input channels (Comp1, Comp2 and S-VHS). Therefore you can see only six live videos in the described hardware configuration.
If you have connected two cameras to one DFG/1394-1 and switch the input channel from Comp1 to Comp2 the DFG/1394-1 needs some time to synchronize to the new video camera. This duration can be up to 100 ms.
It is possible to open the DFG/1394-1 with the Grabber object, start the live video and change between the input channels without stopping the live video.

You may download IC Capture Trial version (http://www.1394imaging.com/products/software/iccaptureprof/) and test the change of the input channels during the live video is shown. If both cameras a synchronized, the synchronization between DFG/1394-1 and the video camera could be faster, but i never tested this.
IC Capture is also able to open all found video capture devices simultaneously and display all video streams until the bandwidth limitations of FireWire and PCI a reached.

[bhorowit]

Hi Stefan,

Thanks very much!!

Ben

[todwin8]

Ben,
Did you try the suggestions? Did it work?
Have you been able to capture from multipe sources at the same time?

The reason I ask, I have a small video production company and we video a lot of school performances (choir, theater, etc) and I was thinking about building a computer with hot swapable SATA drives, and capture 2-3 DV cameras at one time.
I could then pull the drives and plug them into our AVID Media composer editing system and not have to transfer or re-capture the video.
I can build a dual quad core server to handle the processor load, but I have never tried to capter from 2 or 3 sources at the same time.
Any suggestions would be greatly appreciated.
Thanks
Todd

[Stefan Geissler]

Todd,

Capturing from more than one video capture source at the same time is no problem.

[bhorowit]

I'd like to second Stefan's reply. I no longer work on this part of the project, but the engineer who now does reports a lot of success in simultaneously capturing video from more than one source.