Aquire webcam frames

[henk_kempen]

Hi everyone,

I want to aquire 30 fps with a resolution of 960x720. It doesn't matter in what format. (In a different LV program I want to open them).

I want to simultaneously look at a triggermoment to see at what framenumber he triggered. (so it has to work realtime)

What is the best way to do this (with not too big size)

Probrably this is very vague, because of my bad english, so please answer what you think I mean and I can explain it better.

Best Regards,

Henk

[udka]

Check the example Triggered Grab or search for grab in Help>>Find Examples>> Search.

-Assuming that you have Vision acquisition software.

[henk_kempen]

I have vision, but I want to record everything, before and after triggermoment, at that point I just want to save the framenumber to a textfile, so I can open it in a different VI.

edit: Example triggered grab.vi didn't work, he says attribute not supported by the camera

[udka]

can you explain more on triggermoment please?
-"Record everything" ? if i understand correctly may be you are referring to live images without trigger?
-How you are triggering?
-are you able to access camera in MAX?

[henk_kempen]

-"Record everything" ? if i understand correctly may be you are referring to live images without trigger?

I want to press on a button 'record'', from that moment till I press stop, I want to save all the frames (30per sec.), at the same time (while he is recording) I want to detect a trigger (see next question)
-How you are triggering?

I have a device that drives a steppermotor, if I press a button (hardware on the device) the program must save just the number  (pe. 534) to a textfile, so I can later open the frames and set a cursor in a graph or something by that frame.
-are you able to access camera in MAX?

What do you mean by MAX?

[udka]

Measurement & Automation Explorer (MAX) , please google for it.
-use the grab function to capture live images and snap to take one image
-please check this post http://forums.ni.com/t5/LabVIEW/Trigger-button-click-programatically-after-a-specified-time/m-p/2664...

[henk_kempen]

Thanks for your response, I use the grab function (see attached vi), but the .avi's becomes very big (pe. 36 sec 3,4 GB!), also, he seemes to skip a few frames, because if i record a stopwatch it has less frames. I can't open your examples in other topics, because I use LV 2010 fall.

[henk_kempen]

Is it also possible to capture with a square resolution (like 720x720), If not, is it possible to change the resolution afterwards?

[henk_kempen]

Ignore the question about resolution above, it isn't important anymore

[henk_kempen]

Now the size is normal (I changed the codec to Microsoft video 1), The problem that remains is the fps...

edit: If I record 1:10 afterwards I check the properties and he says: duration: 1:02, also he skipped many frames, anyone an idea?