How can I use the same webcam for displaying video on a gui and a function that is run with the gui. I get a error saying winvideo: The device associated with device ID 1 is already in use. A new videoinput object cannot be created ....while in use

I am making a GUI and I want to display a live video on my GUI with the same webcam i use for collecting data for a function that i run with the GUI. My function uses the webcam to take a snap shot and than calculates a value that is used later in the function. I think i know whats going on but i don't know how to fix it or even if i can. I need to make something global right...but what and where. THANKS IN ADVANCE and here is the error i get.

winvideo: The device associated with device ID 1 is already in use. A new videoinput object cannot be created for this device while it is in use.

Answer 1

[David Sanchez]

Before you create the video object using videoinput function:

obj = videoinput('winvideo',1); % or something similar, I guess

declare it as global:

global obj

obj = videoinput('winvideo',1); % or something similar, I guess

Then, declare the global variable within your function, and then, use the variable, for example, taking an image.

function your_fun(inputvars)
global obj
frame = getsnapshot(obj);

I never did it, but I think it could work

[Richard]

No this did not work....but now i can see live video on my GUI so that's good. I get the same error now when i try to start my function with the push button in my GUI.

Answer 2

[Chaitra]

As you have indicated in your code:

videoinput('winvideo', 1, 'YUY2_640x480');

A new video input object is being created on the same device. This object is already created as you are accessing it via GUI. I would suggest you to use the same object handle to perform further operations.

Instead of using custom GUI, you can use Imaqtool GUI that is shipped with MATLAB.

>>imaqtool