Video for Windows in LabView 7?

[matthias.richwin]

Hello All,

does anyone out there have any experience with Video for Windows, or the Windows Image Acquisition API? And interface VIs to capture images in LabView?

Regards
Matthias

[Johnner]

Matthias,

Last fall I used an ancient, but effective VFW API written by Eric Eilebrecht to get Webcam images with LabVIEW 7 on XP. It was recommended elsewhere on this forum. Here's where you can find it:

http://www.info-labview.org/the-archives/vi/lv4/lv_vfw.zip

--John

[Steven_H.]

NI also recently released VIs to capture images from USB cameras. Check this link.

Steven H.

[matthias.richwin]

Hi,

thanks for your help. The NI IMAQ driver for USB cameras seems to require the Vision module, though. For just automatically taking a snap shot, this seems a bit too expensive. I will be looking at calling the Windows API directly... there is an interface called "Windows Image Acquisition Automation SDK" which looks promising and can be called via the ActiveX communicaton vi's.

Regards
Matthias

[Mozill]

Hi Matthias,

I would like to do image capture just like what you did without using any vision development module. How did u proceed through the use of windows API. Could you please explain me in steps. I am totally new to this area.

Thank you.

Mozill

[matthias.richwin]

Hi,

since this thread is about 1 1/2 years old, things have changed a little. We are now on LabVIEW 8.2, and decided to buy the Vision Toolkit. So - no news regarding the Windows API. Sorry!

Best regards
Matthias

[rolfk]

---

@Mozill wrote:
Hi Matthias,

I would like to do image capture just like what you did without using any vision development module. How did u proceed through the use of windows API. Could you please explain me in steps. I am totally new to this area.

Thank you.

Mozill

---

Considering that you are total new in this I think there are better ways to spend your time. The Video for Windows API is old and considered legacy technology but that does not mean it is simple. Interfacing this to LabVIEW is not really feasable without using an external DLL that tranlates between the API and LabVIEW, both for datatypes and callback functions.

There has been one library from Pete Parente at http://www.cs.unc.edu/~parente/labview/index.shtml that uses VfW to access webcams.

The modern way to access video on Windows however is DirectX/DirectShow or whatever MS will call it tomorrow. This is however an object oriented API (OLE style) and definitely requires you some good understanding of COM/OLE. Again without an external DLL this is definitely not possible.

Last but not least you will have to think about how to display the image or video in LabVIEW. For images you could use a picture control but for video that is simply not a good idea. The overhead of translating your frames into a Picture stream and have the Picture Control render it onto the screen will make it VEERY slow. IMAQ Vision really has a good use there.

Basically if you know C well with knowledge about pointers and callbacks etc. and can program a DLL it is a feasable project to do as long as you have a few weeks of spare time. Otherwise go with the flow and use what is there. There are lots of people that would want to get a free video interface in LabVIEW but nobody that wants to spend that much time to provide such a solution for free.

If IMAQ Vision is to expensive for you you may also consider IVision instead from Hytek Automation http://www.hytekautomation.com/. Less expensive and with a very extensive image manipulation library too, but it is definitely not free and I would think this to be a very fair price.

Rolf Kalbermatter

Message Edited by rolfk on 02-15-2007 08:47 AM

[Mozill]

Hi Rolf,

I am making a temperature monitoring system where the webcamera will be installed on the moving robot. The theses I am working on is not for any commercial purposes. It is only going to be used for academic demonstration purpose until April 2007.  So, capturing video is not major task I will be utilising too much time on. I will be capturing two videos from two different webcameras simultaneously. Caputuring videos is not the prime target of my theses. I just have two weeks left to get the work done. So, according to you, which one is an easy and less time consuming task for me. I can just use the evaluation version (in case of vision development module) until April 2007 and do not have to pay a penny.
Any recommendations are appreciated.

Thank you very much for your time.

Mozill