How to log acquired data to disk, and save the video file as mp4 or .avi ?

Hi,

I am trying to log acquired data to disk, and save the video file as mp4 or .avi, but it doesn't create any file in the folder? Any advice would be appreciated.

thanks.

clear ;
 close all;
 vid = videoinput('winvideo', 1, 'YUY2_640x480');
 
 vid.Timeout = 20;
 set(vid, 'FrameGrabInterval', 2);

vid.LoggingMode = 'disk';
logfile = VideoWriter('MATLAB.mp4', 'MPEG-4')

vid.FramesPerTrigger = 20;
start( vid );
wait( vid, Inf );
[d t] = getdata( vid, vid.FramesAvailable );
fps =  1 / mean( diff( t ) );
 vid.ReturnedColorSpace = 'grayscale'
 preview(vid);
 start(vid);
 pause(2);

 frames = getdata(vid);
 
 stop(vid)
 clear vid

Answer 1

[Sulaymon Eshkabilov]

Hi,

Probably, you'd need to indicate the directory of your log data as a whole, e.g.: '../dir/videos/MATLAB.mp4'

[Koohyar]

Thanks for your comment, I tried this but didn't work. It goes and saved in memory by removing vid.LoggingMode = 'disk'; and logfile = VideoWriter('MATLAB.mp4', 'MPEG-4').

but I need to log in disk (directory), as mp4 file.

any advice ?

thanks

[Sulaymon Eshkabilov]

you'd need to indcate the directory of your disk completely, e.g.: F:/MY_data/videos/MATLAB.mp4

[Koohyar]

Yes I did exactly the same, but shows error as below:

Logging to disk requires a VideoWriter or an AVIFILE object.

Does that work for you?

thanks

[Koohyar]

I can log to disk according to another script, but not as 'graysclae', whcih I am looking for! I dont know how can I return the colorspace to graysclae?

vidobj = videoinput('winvideo', 1, 'YUY2_640x480');
vidobj.LoggingMode = 'disk'
vidobj.DiskLogger = VideoWriter('logfile.mp4', 'MPEG-4')
vidobj.ReturnedColorSpace = 'grayscale'
vidobj.FramesPerTrigger = 30;
start(vidobj)
wait(vidobj)
while (vidobj.FramesAcquired ~= vidobj.DiskLoggerFrameCount) 
    pause(.1)
end
vidobj.FramesAcquired
vidobj.DiskLoggerFrameCoun

delete(vidobj)
clear vidobj

[Koohyar]

my Matlab version is R2020a