From Github #17
I was trying to use this as part of a general video pipeline, but the script doesn't exit with error codes if there are any problems (other than the one check to verify that ffmpeg exists). This makes it hard to know if it succeeded or not.
With the forked processes for multiple bitrates this may be a little tricky to implement. But it might also be that we can switch away from forking the processes (if I can find my notes from previous tinkering to see why I chose not to use it).
In any case, we should at least attempt to return an appropriate exit status on failure.