IMAQ USB Grab.vi not collecting image, USB Snap.vi does

[goofylogic98]

I am trying to continously collect video data using a USB device.  the USB Snap.vi does great at capturing a single image, however USB Grab.vi returns a blank image.  I don't get any errors when I run the Grab.vi, just no image.  Any help would be appreciated.

[goofylogic98]

In addition, when I opne Vision Assistant 8.6, and go to acquire from USB camera, it shows the moving image.

[rpursley8]

If I recall, there was a bug in the USB Grab that required you to use a RGB (U32) image to get anything out.  Are you trying to acquire a different type of image?

[goofylogic98]

I have tried RGB (U32) and all others, and still get no image at all. 

[goofylogic98]

The camera is a color camera and thus the RGB (U32) is the appropriate one to use.

[rpursley8]

This works for me.

Message Edited by rpursley8 on 07-13-2009 03:42 PM

[goofylogic98]

Still no images are being capture or displayed.  Using a Sabarent USB-AVCPT USB 2.0 Capture device.

[rpursley8]

I kind of see the same thing.  If I use a uEye USB based camera, it works fine.  If I try to use an Avermedia DVD EZMaker USB Gold (similar to your device), the device is detected and opened, but I get an error during acquisition (both Snap and Grab).  I do not know the differences between the drivers for these types of devices, but obviously something is different.

You might try to talk to someone at NI to see if they at least have an explanation as to why.

[OliviaC]

Hi rpursley8,

What exactly is the error that you see?

It is most likely a difference between the USB drivers. Most of out other vision drivers require that the cameras being used are Direct Show compliant. Unfortunately, USB cameras do not have a standard and so we cannot guarantee which cameras the IMAQ for USB will be compatible with. 

[rpursley8]

It is error -1074396024

 Error -1074396024 occurred at IMAQ USB Grab Setup.vi
  Error system.

The Avermedia device does not mention Directshow support in its specifications.  Maybe that is the reason it doesn't work with the USB Camera drivers.