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Henning
May 26, 2004, 17:30:32
Hi there,

I am working with LabVIEW and would like to rebuild the VB6 example "Using Multiple Buffers" in LabVIEW. I'd like to store an image sequence continuously in a Ring Buffer (is this the RAM?) without writing it to the hard disk. Only if an event occurs (e.g. pressing a button) the image sequence from about 2 minutes ago until 2 minutes after the event should be stored permanently.
Is this possible and if so how?

Thanks in advanced for any help,

Henning

Stefan Geissler
May 28, 2004, 16:06:05
Hello Henning,

The ring buffer is allocated memory in the ram. Each ring buffer element stores one complete frame that was delivered by the video capture device. With a solution of 640*480 at 24 bit you need 921600 bytes per image. At a frame rate of 25 frames per second you need to store 23 MB per second. This results in 2,7 GB memory for two minutes. When Windows starts to swap memory, the timing behaviour of Windows is unpredictable and you may loose frames. You can reduce the amount of memory by using a smaller color depth and using a smaller frame rate. With Y800 at 3,75 frames per second this would be possible. If you would use a timer to snap only one image per second, the amount of memory would be acceptable.
Using the ring buffer to save the images before and after the event is the correct beginning. The only problem is the amount of memory.