Trouble with videoinput and dcam device

Hi all,

I'm relatively new to Matlab. I am trying to write a script that takes a live video feed from a Logitech HD Pro Webcam C920. Eventually I want to use edge detection with it rather than a recorded video, but thats not where Im having the issue. I am using Matlab R2014b.

This is my code for creating a videoinput object:

caminf = imaqhwinfo;
mycam = char(caminf.InstalledAdaptors());
mycaminfo = imaqhwinfo(mycam);
resolution = char(mycaminfo.DeviceInfo.SupportedFormats());
vid = videoinput(mycam, 1, resolution);

if I enter the command: imaqhwinfo(mycam), it says that AdaptorName: 'dcam'. However, if I run this code in a script I get the error message:

Error using videoinput (line 233)
There are no devices installed for the specified ADAPTORNAME. See IMAQHWINFO.

Im not really sure where the problem could be here...

Thank you

[Geoff Hayes]

Luke - what happens when you step through the code? i.e. put a breakpoint at the line

 mycaminfo = imaqhwinfo(mycam);

and step through each line. What does mycaminfo become? What is mycam?

[Luke]

So, if I input the lines one by one mycaminfo becomes:

mycaminfo =

       AdaptorDllName: 'C:\MATLAB\SupportPackages\R2014b\dcamhardware\toolbo...'
    AdaptorDllVersion: '4.8 (R2014b)'
          AdaptorName: 'dcam'
            DeviceIDs: {1x0 cell}
           DeviceInfo: [1x0 struct]

and:

mycam =

dcam

[Luke]

I did some digging and found this help thread where they say that if DeviceIDs is {1x0 cell}, it means the computer does not recognize the camera. In the command Window I set mycaminfo.DeviceIDs = 1, but this does not change the situation.

[Geoff Hayes]

Luke - have you installed any (all?) drivers for this webcam? What happens if you run the command webcamlist in the MATLAB Command Window? Does your webcam appear in the list?

[Kais Abu saleh]

hey, i'm having same problem as luke, i tried the command webcamlist and i get an empty list as a result, i've tried everything do you have any idea what to do next?

[Nhat Nguyen Thanh Minh]

install webcam package from Support Package Installer could show you the webcam list

[Dipendra Bhandari]

where do I get a support package installer? i'm facing the exact same problem

[Walter Roberson]

http://www.mathworks.com/help/matlab/ref/supportpackageinstaller.html

[Vishwas Banjan]

http://www.mathworks.com/hardware-support/directshow.html

[Yousef Mohamed]

When i write webcam list it tells me that it identifies the webcam and its name but the same problem occurs does that mean i have to work with a usb cam not the built in laptop cam ?

[Diah Junaidi]

Best way to solve this ---> if the usb webcam doesnt wanna install winvideo but you just have webcam, so you absolutely should choose : Image Acquisition Toolbox Support Package for "OS Generic Video Interface". This is the answer.

[Vijay Hiremath]

Diah Junaidi : It worked as I installed the "OS Generic Video Interface" Thank you so much & U are really osm !

Answer 1

[David Tarkowski]

You are using a Logitech camera which is a webcam. The dcam adaptor does not support webcams. If you are using the videoinput command, you should use the winvideo adaptor.

Since you are using R2014b, you can also use the webcam object. It doesn't have all of the features of videoinput, but has a simpler interface.

[Yousef Mohamed]

winvideo adaptor wasn't installed when i installed image acquisition toolbox how can i install it ?

[Walter Roberson]

https://www.mathworks.com/help/imaq/installing-the-support-packages-for-image-acquisition-toolbox-adaptors.html

[KAE]

Thanks for the link, Walter. It worked for me.

Answer 2

[Duy Dang]

Thank you Vishwas Banjan, it work with your solution.