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View Full Version : Stereo sequence capture with DMK 21F04



pauljurczak
January 21, 2005, 06:19:53
Hi,

is it possible to have frame synchronized (or nearly synchronized) video capture from two DMK 21F04 (or 21BF04) cameras on the same firewire bus?

Paul.

Stefan Geissler
January 21, 2005, 09:25:19
Yes, it is. For bandwidth allocation see here:

http://www.1394imaging.com/resources/backgnd/1394/video_bandwidth

With the 21BF04 you will be able synchronize the images exactly by using an external trigger.

pauljurczak
January 21, 2005, 14:13:59
How accurate is the synchronization with two DMK 21F04 cameras (maximum time difference between start of exposure of stereo pair on two cameras)? What is the latency (time difference between end of frame exposure and frame available for processing in PC memory) on fast PC?

Paul.

Stefan Geissler
January 21, 2005, 17:15:17
Paul,

this is a very good question. Since Windows is no real time operating system, there is no way to say something about the latency times. But i think, the time difference between images from should not be more the two or three images.
I did not test this.

pauljurczak
January 21, 2005, 17:44:27
Stefan,

I presume that you mean latency is two or three frames. What about stereo synchronization (maximum time difference between start of exposure of stereo pair on two cameras)?

Paul.

Stefan Geissler
January 21, 2005, 17:50:09
Paul,

you can not synchronize two DMK 21F04 cameras. They have no external trigger input. If you would use cameras with external trigger input, then you can synchronize cameras excatly. The DMK 21BF04 will have an external trigger input.
This means: While the external trigger signal does not occur, no images are delivered, and no data is send through FireWire. Then the trigger triggers.. Both cameras start to send their images. When the computer has revieved the images from the camera, the capture software can get them. May be, the images are recieved with a little time latency, but they are completely catched at the same point of time. If the capture software has reveiced both images, the next trigger impuls can be engaged.
This is the only way i know to synchronize images from different cameras,