Inter-app audio routing is - as you can imagine - something we take seriously here at Cycling ‘74. For a while, we were supporting the Soundflower program/driver setup, which allowed you to create virtual audio streams and capture/route them as needed. It was a great tool for creative audio folk, but it was also fraught with issues (mainly due to changes in the underlying operating system technologies) - and became impossible for us to support. Rogue Amoeba took over support for a while, then passed it back to its original author - Matt Ingalls - who now provides the source on his Github site.
What It Is
Rogue Amoeba also has a long history of creative audio tooling, and has extended the audio routing concept with a new product: Loopback. Rather than acting like a audio pipeline, Loopback is a driver-level system that can work with specific audio-enabled packages, turning the audio I/O pipeline into a stream that is mighty easy to capture, use and monitor.
There is a Loopback application, which allows you to set up virtual drivers - each one can be set up for specific source applications, monitoring applications and channel routings.
Once the setup is complete, each of the virtual drivers shows up as an individual audio source in Mac CoreAudio applications.
From there, you are just running per normal. Internal differences in streams are managed by Loopback, and I’ve not found a situation where it was confused. It’s a solid piece of engineering, and hasn’t caused any problems either in the routing or at the operating system level.
How Do I Use It?
If you can’t imagine a use for Loopback (and I’m actually betting you already have…), you can think of it as a patchbay for your studio, but housed inside your computer. You can shoot audio throughout your system, and record/effect/mangle with almost any program that can speak Mac audio. It holds a few important positions on my laptop: I use it for recording Skype conversations, for quickly piping audio from Max to my recording software, or for snagging police calls from my copy of iScan (a police-and-fire scanner package available on the App Store). It’s a great way to capture anything, and since it avoids entanglement with other software packages, it’s not as invasive as Soundflower was.
Some pieces of software stand proudly on your desktop screen, and they are first-click items every time you turn on your system. But it is often the subtle, less-visible software products that really make your system hum, and Loopback is one of those for me. Worth every cent, and part of my everyday quick-and-effective toolkit.
Loopback - US$99, or bundled with Audio Hijack for $130 by Rogue Amoeba