Help with IMAQ IEEE1394 buffer VI's

[Frank_Rizzo]

I'm using the "IMAQ 1394 Grab Acquire.vi" in a while loop to monitor an experiment.  I gave the user the option to record an AVI or to take a screen shot and save it as a bitmap.  One thing I would like to add is a buffer that would allow the user to capture the last XX seconds of data if an incident were to occur and they were not recording at that time.  If the user were to hit the "capture buffer" button I would like to dump the contents of the buffer and create an AVI.  Does anyone have any suggestions or examples to help me accomplish this?  Thanks for your time!!!

[VuD]

Hello Frank,

Typically buffered acquisition is handled using a "ring".  A ring initiates a continuous high-speed acquisition to multiple buffers and is appropriate for high-speed applications that perform processing on every image.  Here is some more information about ring acquisition.

Developer Zone: Ring Acquisitions

Here is a document which explains how to do a ring acquisition with your IEEE 1394 camera. 

KB 497CAQBE: Ring Acquisition with an IEEE-1394 Camera

If you have the Vision Development Module, you could also monitor the frame numbers of an AVI file and pull certain frames (i.e. the last x frames acquired) by using the "IMAQ AVI Read Frame" VI.  You can configure an event or some other sort of condition that will extract the images/frames based on a user control. I hope this helps get you started.

Vu