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multiple USB cameras in Labview

Hi Angiras,

 

"...I tried copying and pasting the .vi and running both parts in one loop, but ..."

 

what do you mean with it, which loop? What exactly is not working? Do you get any images, from maybe only one camera? I don't have 4 cameras now, but i tried the original example and it works with two.

 

On which system are you working? The example was made on WinXP.

 

Mike

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Message 31 of 47
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Hi,


So I have edited WebCam.Example03 and I can switch between different usb cameras and it works. But now I want to save a sequence of pictures. I am new to LabView and all the image tools that I see need an "image arraye" input but all I have in the program is the handle of the window. If I am correct, there should be a way to tell the program to read the image from that handle but I don't know how, could anyone help me with that? I am using LabView 8.0 on windows XP


Best,

Arash

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Message 32 of 47
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Hi Arash,

 

Could you upload your working version please?  Are you able to get streaming video on multiple cams or is it one image at a time?  what are your frame rates?

 

Thanks

 

Puya

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Message 33 of 47
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Hi Puya,

I could not have both camera runnig at the same time but as far as I understood it was the problem with the memory and other hardware limitations, so now I look at one camera at a time and can switch to a other one while running the program. Next step is to save the sequence of images.

Since yesterday I found out that if I send a WM_CAP_GET_SEQUENCE to camera in principle I could get the sequence in c:\capture.avi and I could control the parameters with WM_CAP_GET_SEQUENCE_SETUP, but still the output is not working and beside I don't know how to specify the file path.

Attached is the main file WebCam.Example05.vi and the WebCam.savefile.vi which I currently am working on to be able to save the image sequence. all the other subVI are same as the files provided previousely in this topic.

Best,
Arash

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Message 34 of 47
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So I wrote a dll to pass the structure that has the information to set my capture properties. But this does not work, anyone could help me on that?

attached are the new savefile and the cpp file for dll (it does not allow me to attach dll)

 

any help would be appreciated

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Message 35 of 47
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Hi aarash,

 

Could you explain a little more?  What are you trying to accomplish with this dll?  What do you mean by not working?

 

Since this is an older post it would probably be best to start a new discussion, especially if it is a different question.  You would get more views and possibly a quicker response.

Justin D.

Applications Engineer
National Instruments
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Message 36 of 47
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Hi Justin,

 

thanks for the suggestion I have made a new topic here: http://forums.ni.com/t5/LabVIEW/Capture-USB-camera-with-user32-dll/td-p/1571476

 

and tried to explain what my question is exactly.

 

Best,

Arash

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Message 37 of 47
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hi friend,i'm quite new to labview and i am needing the same thing also. i've tried the example but i am missing 5 sub vi,advise me wat i shud do plz.

thnx

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Message 38 of 47
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Hi,

 

     Which Vis are you missing? I guess that you don't have NI Vision installed, and that you need the library for vision. There is 2 ways to obtain what you need. Install NI vision, which should install the lib, or just install NI vision module like when you install NI-VISA for a RS232 communication.

 

 

note, Did you went there? "http://forums.ni.com/t5/LabVIEW/Capture-USB-camera-with-user32-dll/td-p/1571476" ?? 2 post up

This thread is a very old one... I were here like 5 or 6 years ago... (I still receive email of these thread... very funny...) if you're new to Labview, Then I understand that you hang here, but I'll recommand to build it from scratch, since it may have a better way those day to do what you need... or take a look at the NEW thread... 😉

 

Hope that I'm helping you a little bit...

 

Good luck!

 

Fak

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Message 39 of 47
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Hi again.you surely a pro in labview, thnx for your advice. by the way the missing sub VI's from the errors are:

'user32.Get desktop.vi'

'WebCam.CreateCaptureWindowsA.vi'

'user32.FindWindowA.vi'

I had previously installed IMAQ 4_6_4. Is that not an NI vision?

 

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Message 40 of 47
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