Feature Request: Adding `sox` command

Hi,
Thanks ton for the amazing package.

I wanted to request addition of [SOX](http://sox.sourceforge.net/Main/HomePage)
Along with ffmpeg, this can be a powerful combination.

Envisioned use case

- screen record on iPad
- create a shortcut to send the recorded video to a-shell
- use ffmpeg+ sox to clean background noise (http://www.zoharbabin.com/how-to-do-noise-reduction-using-ffmpeg-and-sox/)
- send the cleaned video back to file system for share screen from a-shell

With ffmpeg binaries already available for a-shell, this could be a gamechanger!

The license for sox seems to be GPLv2 or LGPL https://en.wikipedia.org/wiki/SoX
Aside - is there a page for some existing shortcuts interacting with a-shell? That would be very useful!