FFMPEG works from command line but not PHP

FFMPEG works from command line but not PHP

I have a strange situation that has just happend. FFMPEG is no longer
executing from PHP but will from the command line.
Here is exactly what the command is:
ffmpeg -i ../../uploads/ee78d5deb564901626067cc0008456ed.mp3 -ab 96k -y
../../uploads/mp3/ee78d5deb564901626067cc0008456ed_6203688.mp3
How it is executed in the PHP script:
if(! exec("ffmpeg -i
".$target_path."".$hash_filename.".".$path_extension." -ab 96k -y
".$target_path."mp3/".$hash_filename."_".$session_ID.".mp3")){
echo 'ffmpeg failed';
}
This command did work but not longer does. I have recently updated plesk
but I highly doubt that has affected this. The only thing that I think
could affect it that I have recently done is have the file upload go to a
subdomain. So the directory where the file is located and stored in the
command is in a directory outside the document root. However, the
move_uploaded_file function works and I have altered the open_basedir in
PHP ini to the webspace root.