gui and web camera muti access

hi every one i made project in matlab 2009 contains GUI when GUI started ,timer function while start and this function use camera to recorde video but in same time i want to preview video in axes inside GUI how can i do this???? or if any way to multi object access to camera in same time??

thanks ...

Answer 1

[Jacob Mathew]

Hey Syed,

I understand that your query is to create a MATLAB App that lets you record a video while also showing you the preview of what is recorded within the app.

To achieve this, we can createa a private property that holds a webcam object. This object can then be used to both preview the video onto a UIAxes component while also being used by the Video Writer to write the video to video file.

The following code demonstrates this approach:

classdef recorder < matlab.apps.AppBase 
    % Properties that correspond to app components 
    properties (Access = public) 
        % Component Properties 
    end 
    properties (Access = private) 
        cam % Camera Object 
        isRecording logical = false % Track the recording state 
        videoWriter % Video Writer Object 
        timer 
    end 
    methods (Access = public) 
        function updateLiveFeed(app) 
            frame = snapshot(app.cam); 
            image(app.UIAxes, frame); 
            drawnow; % Update UI 
            % Write frame to video if recording 
            if app.isRecording 
                writeVideo(app.videoWriter, frame); 
            end 
        end 
    end 
    % Callbacks that handle component events 
    methods (Access = private) 
        % Code that executes after component creation 
        function startupFcn(app) 
            % Initialize webcam and timer 
            app.cam = webcam; 
            app.timer = timer('ExecutionMode', 'fixedRate', 'Period', 1/60, ... 
                'TimerFcn', @(~,~) updateLiveFeed(app)); 
            start(app.timer); 
        end 
        % Button pushed function: RecordButton 
        function RecordRecordButtonPushed(app, event) 
            if ~app.isRecording 
                % Start recording 
                app.isRecording = true; 
                app.RecordButton.Text = 'Stop'; 
                % Initialize video writer 
                app.videoWriter = VideoWriter('recordedVideo.avi'); 
                open(app.videoWriter); 
            else 
                % Stop recording 
                app.isRecording = false; 
                app.RecordButton.Text = 'Record'; 
                % Release video writer 
                close(app.videoWriter); 
            end 
        end 
    end 
    % Component initialization 
    methods (Access = private) 
        % Create UIFigure and components 
    end
end

The app interface should look as follows:

Once you record a video, you can see it show up in the same directory as the app:

You can refer to the documentation of Video Writer below:

https://www.mathworks.com/help/releases/R2024b/matlab/ref/videowriter.html

Also, to use the webcam, ensure that you have MATLAB Support Package for USB Webcams Add On package installed. You can find the link to the Add On below:

https://www.mathworks.com/matlabcentral/fileexchange/45182-matlab-support-package-for-usb-webcams