Feature request: choose a specific software as a casting source

[amergin]

First of all, thank you for providing this wonderful software, which I use on a daily basis.

One feature I very much would like to see here is the option to grab a specific audio stream from a running application.

For example, on a daily basis I run Spotify, Chrome browser and other applications on my laptop. For instance, I would like choose to cast only music from the Chrome. That way, if I get Windows notification sounds when working on other stuff, they wouldn't show up on the audio stream.

This feature is already implemented in Airparrot and in Airfoil, so I would think it is technically plausible to implement: