Apple AirPlay comes with a hidden gotcha. Not the “stream-must-travel-through-the-iPhone” gotcha. That’s well-known. I’m speaking a few totally different, much less apparent gotcha. Awwwwww.
What follows is predicated on analysis performed by a Darko.Audio Patron – we’ll name him Brother Thomas – whose work confirms the long-standing rumours that Apple AirPlay isn’t all the time lossless. Typically it’s, typically it isn’t. In sure circumstances, AirPlay compresses the audio right down to a lossy format earlier than sending it throughout to the community streaming endpoint within the hi-fi rack. In different phrases, AirPlay typically discards audio knowledge and it does so with out telling us.
As we progress, issues will turn out to be slightly technical (however hopefully not too technical). I’ll attempt to preserve Brother Thomas’ findings as layman-relevant as potential however as all the time, for those who care not for the final ounce of sound high quality when streaming music, you possibly can alight right here.
Moreover, AirPlay has by no means been able to streaming hi-res audio with out downsampling it to CD high quality. Such pattern price down-conversion isn’t as audible – or as troublesome – as lossy compression. No less than, that’s the way in which I hear it.
Apart from, the hi-res content material offered by Apple Music, Tidal, Qobuz, Deezer and Amazon Music HD nonetheless sits at lower than 10% of all titles. As we speak we concern ourselves with the 99.9% of all titles which might be obtainable in CD high quality. It’s from this 16bit/44.1kHz music base that we are going to dig into when and why Apple’s AirPlay transmission scheme offers us lossy-compressed audio.
OK. Let’s start.
Apple’s AirPlay is available in two flavours: AirPlay 1 and AirPlay 2.
Launched by Apple in 2010, AirPlay 1 allowed customers to stream audio straight from their iPhone or iPad (or MacBook/iMac) wirelessly to an AirPlay-equipped receiver. Again then, it wasn’t referred to as AirPlay 1. It was referred to as AirPlay. However as a result of at the moment we have to clearly differentiate between AirPlay 1 and a pair of, I’ll proceed to consult with the unique AirPlay as AirPlay 1.
One early instance of an reasonably priced AirPlay 1 receiver was Apple’s AirPort Categorical which might be linked to a DAC over TOSLINK. Nevertheless, hi-fi {hardware} producers have been fast so as to add AirPlay 1 compatibility to their streaming merchandise. A number of even circumvented Apple’s personal certification course of with the Linux-based Shairport plugin.
AirPlay 1’s first gotcha was that the digital audio stream travelled by means of the iPhone or iPad on its solution to the streaming endpoint. Stroll the iPhone (or iPad) out of community vary – or flip it off – and the music quickly stops. We’ve identified this since day one.
AirPlay 1’s second gotcha is successful to the iPhone’s battery run time. AirPlay 1 transmission sees the iPhone convert any incoming stream to 16bit/44.1kHz ALAC – thus sustaining a minimal of CD high quality – earlier than making a two-second knowledge buffer and repeatedly streaming audio knowledge in real-time to the AirPlay 1 receiver. That is all in line with Brother Thomas’s findings:
Word the usage of the phrase “repeatedly”.
Additionally be aware: “CD high quality”.
By the way, that two-second knowledge buffer is why play/pause actions with AirPlay 1 can appear slightly laggy and likewise, as we will see, why AirPlay 1 could be extra susceptible to dropouts than AirPlay 2, which Apple launched 2 in 2018.
AirPlay 2 took purpose at a few of the unique’s gotchas. It was designed to:
- enhance the responsiveness of play/pause actions
- to decrease the incidence of dropouts
- to scale back its influence on the host system’s battery runtime
AirPlay 2 additionally added multi-room help, permitting customers to stream to a number of AirPlay 2 receivers round the home. Maybe most significantly, AirPlay 2 would even be backwards-compatible with AirPlay 1. An AirPlay 1 transmission might arrive at an AirPlay 2 system with out problem – and vice versa.
In accordance with Brother Thomas, AirPlay 2’s new and improved streaming mode would see an AirPlay 2-operating iPhone transmit an preliminary knowledge burst of as much as 3MB to the AirPlay 2 receiver – with a purpose to set up a buffer – after which stream extra knowledge chunks at 10-second intervals. These intervals inform us that AirPlay 2 streaming isn’t steady (as it’s with AirPlay 1).
The profit to battery life is apparent nevertheless it raises an necessary query: how is AirPlay 2 carrying CD-quality knowledge when it’s solely transmitting 10% of the time? The reply is: it isn’t. Any CD-quality stream emanating from a web based service or NAS is transcoded to AAC 256kbps by the iOS app earlier than it’s despatched to the receiver to execute a small hit to audio high quality.
This discovering jives with What Hifi’s AirPlay 2 explainer piece (final up to date in March 2023) that reads: “Nevertheless, the information isn’t so good with reference to utilizing AirPlay 2 to ship lossless Apple Music streams. Apple Music’s Lossless streams supposedly convert from ALAC (Apple’s lossless codec) into AAC (Apple’s lossy codec) at a reasonably lowly 256kbps when transmitted over AirPlay – and subsequently not losslessly.”
Discover how I wrote “iOS app” above, not iPhone (or iPad). We’re accustomed to considering of streaming endpoints as being AirPlay 1 or AirPlay 2 succesful and trendy iPhones (fifth Gen and past) and iPads (fifth Gen and past) are already geared up with AirPlay 2 smarts. However there’s a recent wrinkle: in line with Brother Thomas, our chosen streaming app’s operational mode can additionally be set to AirPlay 1 or AirPlay 2 by the developer.
Assuming the presence of a contemporary iPhone or iPad, lossy audio compression solely takes place when an AirPlay 2 app streams to an AirPlay 2 endpoint. An AirPlay 1 app streaming to an AirPlay 2 endpoint will revert to AirPlay 1’s real-time steady streaming mode, ergo no AAC compression. Ditto an AirPlay 2 app streaming to an AirPlay 1 endpoint. Put extra merely, anybody streaming to (or from) an AirPlay 1 system will all the time get pleasure from lossless CD-quality streams.
So now you in all probability questioning which apps stream in AirPlay 1 mode and which stream in AirPlay 2.
Let’s get Roon out of the way in which as a result of the audio doesn’t originate from an iPhone or iPad however from a Roon Core (server), which has been coded by Roon Labs to stream in AirPlay 1 mode. The upshot is that CD-quality streams stay untouched by AAC compression. Phew.
Nevertheless, if we pull up a CD-quality stream from Apple Music on, say, an iPhone 13 Mini and ship that stream to a WiiM Professional Plus linked to a hi-fi system, the stream might be AAC compressed by Apple Music’s iOS app earlier than dispatch. That’s as a result of the Apple Music app, in line with Brother Thomas, operates in AirPlay 2 mode. And so too does the Tidal iOS app.
Qobuz customers can breathe simple. The French streaming service’s iOS app (at time of writing) runs in AirPlay 1 mode. So too do Amazon, Plex/Plexamp, Soundcloud and Spotify, once more in line with Brother Thomas’s analysis.
Proper now, a few of you may be considering: “However my iPhone does multi-room streaming with the Qobuz app, in order that should imply it’s AirPlay 2!” Not fairly. Multiroom capabilities appear to be set on the {hardware} stage: by the receiver and the transmitter. An AirPlay 1 app working on a later-generation (learn: AirPlay 2-equipped) iPhone or iPad will stream in lossless CD high quality to a number of AirPlay 2 endpoints.
Confused? Fortunately, Brother Thomas has kindly summarised his findings in a desk:
The underside line: it’s solely when 1) the streaming app, 2) the iPhone/iPad mannequin on which that app runs and 3) the streaming endpoint are all AirPlay 2-equipped that the stream is lossy compressed to AAC 256kbps.
Brother Thomas additionally neatly factors out that an iPhone/iPad will point out an AirPlay 1 reference to a tick however will put that tick inside a circle when an AirPlay 2 connection is current:
AirPlay 1
AirPlay 2
Why can we name him Brother Thomas? As a result of he’s doing God’s work.
Additional info: Nope
