Things to check:
Does the
in.mp4
file actually exist on the server and is it in the correct temporary folder?Check that file size limits (
upload_max_filesize
PHP setting) are not being hit.Does the
ffmpeg
command work properly from a shell promt as the user that the webserver is running as? (this test should be performed in the folder where you are processing the file) Use the verbose logging options to check for errorsCapture all the output from the
shell_exec
and check for errors. Try usingsystem
orexec
where you can also capture the return value offfmpeg
which can then be used for error checking
Finally, I would specify actual directory names for the input and output files. This will narrow down problems as you know exactly what folder to look in for results. You can also adjust permissions if required