Mountain Lion's AirPlay Feature is Your New Audio Interface

by Nikolozi Meladze

I’ve been running OS X Mountain Lion since its release and I haven’t had any issues. It all works great. If you haven’t already checked out the reviews here are two great ones by John Gruber and John Siracusa. I think, Siracusa sums it up best — “Where Lion stumbled, Mountain Lion regroups and forges ahead.”

Apple updated iWork along with the Mountain Lion release, and now they properly support retina display. I’ve complained about this in the past and it’s great to see it resolved. But I’m still waiting for a Logic Pro (and GarageBand) update for the retina display. All other Apple mac apps are retina ready, including the professional ones — Final Cut Pro X & Aperture. But I digress.

Admittedly, the most exciting feature in OS X 10.8 Mountain Lion for audio engineers and producers is AirPlay. I dream of wireless studios. This brings us a step closer. If you launch any DAW and check its audio interface settings, you’ll notice that AirPlay will appear as one of the CoreAudio drivers. This means you can stream your stereo output to AirPort Express, Apple TV or any other receiver that supports AirPlay. You can have one of these devices connected to your studio speakers and you are set. I have a great setup at home right now. I have my studio speakers in the lounge, which are connected to my Apple TV. I can stream audio from my MacBook Pro straight from my couch. There is no need for a cable running across the room making things look ugly.

Now, there are two concerns using AirPlay as your audio interface. First, sound quality that’s being streamed to the speakers and the second, audio latency. Fortunately, they are not issues. According to wikipedia AirPlay streams lossless audio:

The AirTunes part of the AirPlay protocol stack uses UDP for streaming audio and is based on the RTSP network control protocol. The streams are transcoded using the Apple Lossless codec with 44100 Hz and 2 channels encrypted with AES, requiring the receiver to have access to the appropriate private key to decrypt the streams

Here are AirPlay & Built-in sound card audio latencies for 256 samples buffer size (screenshots of Logic Pro’s Core Audio settings):

The audio latency for AirPlay is only 111.6ms. Sure it’s much greater than built-in audio card’s 6.0ms latency, but the audio latency of 111.6ms is quite usable when making music. Even if you have a MIDI keyboard connected to your DAW hearing sound feedback on MIDI note on after 100ms is bearable. I’ve tried it and it’s more than usable. But the audio latency will improve in the near future anyway, with the faster wifi chips.

It’s interesting to note that the audio latency is much longer when using GarageBand on iOS. I tried using GarageBand on my iPad, I timed the AirPlay latency using a stopwatch. Time difference between strumming a virtual guiater and hearing it on my speakers is 2.2 seconds. This makes the app completely unusable for creating music while streaming the audio using AirPlay. Playing back a composition is fine, of course. I don’t know why there’s such a big difference between the Mac and the iPad.

In conslusion, wireless studio is no longer an unrealistic dream. Maybe in the near future will be able to stream microphone audio output straight to the DAW apps.