Added some more help text for function

README.md

@@ -9,7 +9,8 @@ packaged on PyPi. You should clone the project to your local machine and
 do an [editable install](https://pip.pypa.io/en/stable/topics/local-project-installs/#editable-installs) 
 in a [virtual environment](https://docs.python.org/3/library/venv.html).
 
-Note: You will also need ffmpeg.
+Note: You will also need ffmpeg and ffprobe in order to interrogate audio 
+files for their metadata.
 
 ```sh
 $ brew install ffmpeg