Savingsame video several times with while loop

Hello,

I have some video that i have to cut several times at different moment of the video. But when it tries to verify if the "filename_1.mp4" exist it just stop saying that it exist and cannot save the next one.

I tried this but still doesn't work :

%% video editing
%save current location
disp('outputing videos')
outputfile = [namevids '_1.mp4'];
i=1;
while exist(outputfile)
    i=i+1;
    outputfile = [namevids '_' num2str(i) '.mp4'];
end
comm = ['ffmpeg -i "' VideoDataPath '" -vf crop=' num2str(cropdim(1)) ':' num2str(cropdim(2)) ':' num2str(cropTL(1)) ':' num2str(cropTL(2)) ' -ss 00:' num2str(tstartmin,'%02.f') ':' num2str(tstartsec,'%.3f') ' -to 00:' num2str(tendmin,'%02.f') ':' num2str(tendsec,'%.3f') ' "' pathvid '\' outputfile '"'];
disp('Converting Video')
[status,cmdout]=system(comm);
if status~=0
    error(['ffmpeg failed render, status = ' num2str(status) ' ' cmdout]);
end

fprintf('\nend\n');

Answer 1

[Dyuman Joshi]

When checking for a file with an extension using exist(), you need to compare the output to 2.

%% Example
y = primes(50);
writematrix(y, 'file.xlsx')
exist('file.xlsx')

ans = 2

Refer to the description section of exist for more information.

Do you have to repeat this operation for multiple video files?

[Laurine]

Im a super beginner, so i'll try to explain what im trying to do

I just want it to verify by himself if the file named "filename_1.mp4" exist but without telling me and just save the video with the right name :

If its the first video saved : "filename_1.mp4"

if its n video saved : "Filename_n.mp4"

Yes i have to do this with a lot of video files but its only this part who is not working well.

[Dyuman Joshi]

I assume the all files are saved in the same folder.

Instead of checking for each file, a better approach is to get all the files in the folder and perform operations accordingly.

If there are files with .mp4 extension in the folder, that you do not want to work with, you can either relocate them or check the filename if it includes the phrase "Filename_" or not, using contains

%Read all the files in the folder that end with .mp4 extension
arr = dir('*.mp4');
n = numel(arr);

%loop through the files
for k=1:n
    %this will give the name of the kth file   
    outputfile = arr.name(k);
    
    %performing operations accordingly
    comm = ['ffmpeg -i "' VideoDataPath '" -vf crop=' num2str(cropdim(1)) ':' num2str(cropdim(2)) ':' num2str(cropTL(1)) ':' num2str(cropTL(2)) ' -ss 00:' num2str(tstartmin,'%02.f') ':' num2str(tstartsec,'%.3f') ' -to 00:' num2str(tendmin,'%02.f') ':' num2str(tendsec,'%.3f') ' "' pathvid '\' outputfile '"'];
    [status,cmdout]=system(comm);
    if status~=0
        error(['ffmpeg failed render, status = ' num2str(status) ' ' cmdout]);
    end
end

[Laurine]

i resolved by changing everything :

%% video editing
% save current location
disp('outputing videos')
outputfile = [namevids '_1.mp4'];
i = 1;

while i <= 100
    % Check if the file with the current name exists
    if ~exist(fullfile(pathvid, outputfile), 'file')
        break; % File doesn't exist, exit the loop
    else
        i = i + 1;
        outputfile = [namevids '_' num2str(i) '.mp4']; % Construct the next filename
    end
end

% Check if we reached the maximum iterations without finding a suitable filename
if i > 100
    error('Unable to find a suitable filename.');
end

% Continue with your existing code to process and save the file
comm = ['ffmpeg -i "' VideoDataPath '" -vf crop=' num2str(cropdim(1)) ':' num2str(cropdim(2)) ':' num2str(cropTL(1)) ':' num2str(cropTL(2)) ' -ss 00:' num2str(tstartmin,'%02.f') ':' num2str(tstartsec,'%.3f') ' -to 00:' num2str(tendmin,'%02.f') ':' num2str(tendsec,'%.3f') ' "' fullfile(pathvid, outputfile) '"'];
disp('Converting Video')
[status,cmdout] = system(comm);

if status ~= 0
    error(['ffmpeg failed render, status = ' num2str(status) ' ' cmdout]);
end

fprintf('\nend\n');