Recording a Video From Webcam Using MATLAB Code

Recording a Video From Webcam Using MATLAB Code is a very simple task if, you know how to access your webcam or other imaging device using MATLAB & snapping from them.

Click Here to know more about accessing Webcam using MATLAB code.

Click Here to know more about snapping an image from Webcam using MATLAB code.

Code:

clear all;

close all;
clc;

% Constructing a video input interface 
vid = videoinput('winvideo',1,'YUY2_640x480');

% setting the frame rate as 12 (it will depend on your webcam device also)
set(vid,'FramesPerTrigger',12);
set(vid,'FrameGrabInterval',10); 
start(vid);
wait(vid,Inf);

% Retrieve the frames and timestamps for each frame.
[frames,time] = getdata(vid, get(vid,'FramesAvailable'));

% Calculate frame rate by averaging difference between each frame's timestamp
framerate = mean(1./diff(time));
capturetime = 30;

%The FrameGrabInterval property specifies how often frames are stored from 
%the video stream. For instance, if we set it to 5, then only 1 in 5 frames
%is kept -- the other 4 frames will be discarded. Using the framerate, 
%determine how often you want to get frames
interval = get(vid,'FrameGrabInterval');

%To determine how many frames to acquire in total, calculate the total 
%number of frames that would be acquired at the device's frame rate, 
%and then divide by the FrameGrabInterval.
numframes = floor(capturetime * framerate / interval);

%If a large number of frames will be acquired, it is more practical to log 
%the images to disk rather than to memory. 
%Using the Image Acquisition Toolbox, you can log images directly %
%to an AVI file. We configure this using the LoggingMode property.
set(vid,'LoggingMode','disk');

%Create an AVI file object to log to, using the avifile command. 
%We must specify the filename to use, and the frame rate that 
%the AVI file should be played back at. Then, set the DiskLogger property 
%of the video input object to the AVI file.
avi = avifile('timelapsevideo.avi','fps',framerate);
set(vid,'DiskLogger',avi);
start(vid);

wait(vid,Inf); % Wait for the capture to complete before continuing.

%Once the capture is completed, retrieve the AVI file object, and use the 
%close function to release the resources associated with it.

wait(vid,Inf); % Wait for the capture to complete before continuing.

avi = get(vid,'DiskLogger');
avi = close(avi);

%When you are done with the video input object, you should use 
%the delete function to free the hardware resources associated with it, 
%and remove it from the workspace using the clear function.
delete(vid);
clear vid;

NOTE: 

# After the code execution you will see a .avi video file in your 

current working Directory as timelapsevideo.avi.

# If the video file is completely black, your camera is slow & thus need some

warm up time to start off. So give delay of 1-2 seconds during the camera capturing

step.

# The following error/warning can also arise, the 1st one is due to the fact that 

"avifile" function is obsolete now & MATLAB has decided to remove in further 

releases.

The 2nd one is due to the fact that the following codec the MATLAB is trying to

use is not installed in your system, so either install it or change it or MATLAB

will self use the 'none' attribute in place of the codec.

Warning: AVIFILE will be removed in a future release. Use VIDEOWRITER instead. 
> In avifile.avifile at 81
  In img at 33 
Warning: Cannot locate Indeo5 compressor, using 'None' as the compression type.
See Mathworks Technical Solution 1-4G50RI for more information.  

Author: Vibhutesh Kumar Singh

An active & prominent author at Digital iVision Labs! Specializing in MATLAB, C++, Arduino, OpenCV, NI Labview, Web Designing & other Electronics stuffs! Just started M.Tech. From IIIT Delhi, looking for excellent PhD Opportunities with prominent researchers. Drop a mail: vibhutesh[at]gmail.com or Follow him at....

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