problem acquiring the video from webcam

hi every one .i am trying to acquire the video frames using the following codes .

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
a = imaqhwinfo;                   

[camera_name, camera_id, format] = getCameraInfo(a);

vid = videoinput(camera_name, camera_id, format);

% Set the properties of the video object
set(vid, 'FramesPerTrigger', Inf);

set(vid, 'ReturnedColorspace', 'rgb')

vid.FrameGrabInterval = 5;

%start the video aquisition here
start(vid)

while(vid.FramesAcquired<=200)

data = getsnapshot(vid);

end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%the camera info routine is as follows 

function [camera_name, camera_id, resolution] = getCameraInfo(a)

camera_name = char(a.InstalledAdaptors(end));

camera_info = imaqhwinfo(camera_name);

camera_id = camera_info.DeviceInfo.DeviceID(end);

resolution = char(camera_info.DeviceInfo.SupportedFormats(end));

%%%%%end of routine %%%

following are the errors i am getting

??? Error using ==> end Incorrect cell or structure reference involving "end". Most likely cause is a reference to multiple elements of a cell or structure followed by additional subscript or structure references.

Error in ==> getCameraInfo at 4 camera_id = camera_info.DeviceInfo.DeviceID(end);

Error in ==> redObjectTrack at 2 [camera_name, camera_id, format] = getCameraInfo(a);

please help me out of this ..Same codes are working for a desktop PC and a webcam..But when i try this on my laptop its not working ..

Answer 1

[Image Analyst]

You can't have a function defined down below your script. I didn't see a function line for the first chunk of your code, which you need. You need something like this as the first line:

function redObjectTrack()

When I do that it runs the getCameraInfo() function fine. All I did was to remove the semicolons so that I could see the outputs, and I renamed format to format1 so as to not overwrite a built-in MATLAB function and it printed out this:

camera_name =
winvideo
camera_info = 
       AdaptorDllName: 'C:\Program Files\MATLAB\R2011b\toolbox\imaq\imaqadaptors\win64\mwwinvideoimaq.dll'
    AdaptorDllVersion: '4.2 (R2011b)'
          AdaptorName: 'winvideo'
            DeviceIDs: {[1]}
           DeviceInfo: [1x1 struct]
camera_id =
     1
resolution =
RGB24_960x720

[Max]

thanks image analyst ...it worked welll

[Walter Roberson]

(As of R2016b it become possible to put a function below a script, but that was not possible in the 2012 time frame.)

[Jibin Lukose]

Me don't have any idea with this MATLAB Track coding, so could you share the edited code, that would run successfully please? @Max & @Image Analyst

Answer 2

[Jiro Doke]

Put a breakpoint on line 4 of your function getCameraInfo, and explore your variable camera_info. Maybe your laptop isn't recognizing your webcam.

Answer 3

[Walter Roberson]

camera_info is a structure array directly or at the DeviceInfo level.

[Max]

function [camera_name, camera_id, resolution] = getCameraInfo(a)

camera_name = char(a.InstalledAdaptors(end));

camera_info = imaqhwinfo(camera_name);

camera_id = camera_info.DeviceInfo.DeviceID(end);

resolution = char(camera_info.DeviceInfo.SupportedFormats(end));

it was at DeviceInfo level

Answer 4

[WORAWUT KUNGHUN]

a = imaqhwinfo;
camera_name  = char(a.InstalledAdaptors(end));
camera_info    = imaqhwinfo(camera_name);
camera_id        = camera_info.DeviceInfo.DeviceID(end);
resolution        = char(camera_info.DeviceInfo.SupportedFormats(end));
vid                    = videoinput(camera_name, camera_id, resolution);
set(vid, 'FramesPerTrigger', Inf);
set(vid, 'ReturnedColorspace', 'rgb')
vid.FrameGrabInterval = 5;
start(vid)

change the resolution in image acquired by webcam command.