usb camera activex

[CSD]

I'm dealing with an ActiveX control in LabView 7.0 that allows me to input video / audio from a USB webcamera. The ActiveX control also allows for the playback of the AVI files that are recorded from the webcam. During playback, I occasionally get a eventoracle.cpp @ line 370 error that is hard to diagnose and hard to reproduce. Any ideas? I do have the ability to move to LabView 7.1.1 if needed, but I have not tried that yet.

Chris Davis

[chrisger]

hi there

i once had an error in eventoracle.cpp when using MSCOMCTL Toolbar, but i can't remember the line number anymore. the error occured after a ActiveX event which i registered with the "Register Event Callback - node.  the whole event - code was in the Callback - VI. then i moved the code to a dynamic event case in the Event Structure of my top level VI and fired the dynamic event inside the CallBack - VI. then all was fine...

best regards
chris

[yeang]

hi chris,

read about how you solved the "eventoracle.cpp" error by registering your event callback as a dynamic event in an event structure. Here I am facing the same problem, can you provide some information on how that can be achieved? or maybe provide a simple sample vi on how dynamic event is registered instead of using the Register Event Callback node?

Thank you in advance.

with regards,

yeang 

[chrisger]

hi there

here it is....

[yeang]

Hi Chris,

Thanks for the sample, I am in the process of integrating the sample program into my own program. However I'm facing a small problem here as i'm trying to capture which callback functions are actually triggering the events. (I have registered more than ten events in my program).

Any advice?

Regards,

yeang

[chrisger]

hi there

you can adjust the user event data type to your needs. for example you can add a string "source" to the events data. additionally you can pass the "user parameter" to the callback vi to specify its location. see attachment below.....

[Mozill]

Hi Chrisger,

                I want to acqire continuous image in LABVIEW using a wireless usb security webcamera. The manufacturer has provided the DirectX drivers for windows on the cd. I am  having hard time finding the usb class for the webcamera. I am totally new to this area. Could you please help me out.


Thank you for your time.

[chrisger]

hi there

first try to find out if the camera is supported by the windows webcam api. if so you can acquire images with this api, you then won't need to use the DirectX interface. I'm not sure but i think supported cameras are shown in the explorers tree at "Scanners and cameras" at the system control. 

[Mozill]

Hi Chrisger,


Thank you very much for a prompt response. The camera does appear in the 'scanners and camera' explorer bar, so according to you what should be my next step?

Thank you very much for your time.

Truly,

Mozill

[chrisger]

hi there

well, then try the links mentioned here

http://forums.ni.com/ni/board/message?board.id=140&message.id=7359&query.id=45618#M7359
http://forums.ni.com/ni/board/message?board.id=170&message.id=168315&query.id=45618#M168315

or search in this forum for "webcam", "usb" etc.