Today I was randomly distracted, trying to make my youtube-dl wrapper script show progress while converting a file to mp3.
The problem is, youtube-dl does not seem to show any indication that it is in fact converting. The only way to know for sure, that I am aware of, is to open up a second terminal window and do something like:
watch ls -s
This will give you a list of the files in a directory, including their file sizes (-s). So, if a file is currently converting, you will see its file size grow, and you will know that the youtube-dl triggered ffmpeg process is working.
The watch command will automatically update every 2 seconds.
Another option is to open the process monitor and look at the CPU use for the relevant process, but, as you may know, even when a process is using a lot of CPU, it could still have silently frozen up. So, the best way I know is to watch the ls command in a second terminal.
Hopefully youtube-dl will include a progress indication for ffmpeg sometime.