If cron is ok, then try to run ffmpeg from SSH command line and see if it can be run on your OS. We updated ffmpeg binary - it still can be run on almost all linux OS'es, but it maybe that not in your server environment - then you need specific ffmpeg binary especially for your system.
If cron is ok, then try to run ffmpeg from SSH command line and see if it can be run on your OS. We updated ffmpeg binary - it still can be run on almost all linux OS'es, but it maybe that not in your server environment - then you need specific ffmpeg binary especially for your system.
Also it maybe just ffmpeg permission problem.