John Darko
Here we go again with Apple AirPlay 2’s mixed behaviour: sometimes it’s lossless and sometimes it’s lossy. This time out, however, we’ve got receipts that anyone can read.
We’ve known for a long time that an AirPlay stream plays gaplessly but travels through the iPhone (or iPad) as it journeys from the cloud to an AirPlay-compatible streaming endpoint. We’ve also known for a while that AirPlay cannot handle hi-res audio. That said, many audiophiles, myself included, would like to use AirPlay – built into every iPhone and iPad (but not Android devices) – to move CD-quality streams from Apple Music to a hi-fi system. And this is where the fun starts…
Earlier this year, Darko.Audio Patreon Brother Thomas discovered that sometimes CD-quality AirPlay streams are sent by the iPhone as is – i.e. losslessly – but that other times those streams are re-encoded in a lossy format by the iPhone before being forwarded to the streaming endpoint. Why pay for CD-quality audio when it doesn’t reach the hi-fi system?
Anyone using an AirPlay 1 endpoint – indicated by a naked tick on an iPhone’s AirPlay screen – can breathe easy. Per Brother Thomas’ research, no matter what generation your iPhone or iPad, AirPlay 1 endpoints will always receive audio losslessly. I still have a couple of AirPort Express knocking about — they are AirPlay 1 receivers. It’s not just older hardware though: many new streaming products use the Shairport plugin* (or similar) to deliver AirPlay compatibility; and they too show up as AirPlay 1 receivers. One example is the Shanling ET3: a CD transport that houses an AirPlay 1 streaming endpoint. IIRC, the Eversolo DMP-A6 and FiiO R7 are also AirPlay 1.
However, a tick embedded in a circle (see image below) indicates an AirPlay 2 endpoint. And this is where the fun starts.
Brother Thomas used a bandwidth monitor to determine how much data travelled across his network when running AirPlay. The amount of data seen in a given time interval told him whether the stream was lossy or lossless.
I have since discovered a much easier method using a WiiM streamer and the corresponding WiiM Home app, whose now playing screen gives us the bitrate of the incoming stream. The newly arrived WiiM Ultra doesn’t do AirPlay – about which I’ll have more to say in an upcoming post – so I’ve fallen back to the WiiM Pro Plus which has a Roon Ready input and an AirPlay 2 input (as indicated by the tick inside a solid circle). We’re interested in what that AirPlay 2 input sees when fed files from different sources.
Let us begin.
I have a FLAC download of Blur’s recently released Live at Wembley Stadium sitting on my Roon Nuclues One server. If I send that album across the network to the Pro Plus’s AirPlay input using the Roon Remote app, the audio stream travels from the Nucleus One directly to the Pro Plus. It does not pass through the iPhone (and does not collect $200). Roon’s Signal Path pop-up tells us that the stream sent by the Nucleus One to the Pro Plus is an AirPlay 2 varietal with a resolution of 16bit/44.1kHz (so: CD-quality).
We now move to the WiiM Home app’s ‘now playing’ screen to see what data rate is arriving at the Pro Plus’s AirPlay input. I could have done this with the iPhone that controls playback but I opted to use a second phone – an Android smartphone – to have both phones sit side by side in a single photo. Click the photo to enlarge it:
You can see the ‘source’ phone on the left showing AirPlay 2, CD-quality and the desination phone on the right showing 900kbps and 16bit/44.1kHz. We’re interested in the ‘900kbps’. As any song progresses, lossless audio’s bitrate varies between 700kbps and 1200kbps. It’s likely that WiiM’s app cannot track those variations in real time and instead shows us ‘900kbps’ to indicate lossless audio’s average bitrate. I am taking this as an indication that the Pro Plus is receiving lossless audio.
We can repeat this lossless control test with Plexamp. However, Plexamp on an iPhone works differently to Roon: the AirPlay stream travels from the Plex server (in my case, a NAS) through the iPhone and then on to the WiiM Pro Plus. To confirm as much, I turned the iPhone off and the music stopped. I played the extended version of The Style Council’s “Long Hot Summer” with Plexamp showing a 16/44 FLAC file being dispatched and Wiim’s Home app indicating receipt of a ‘900kbps’ stream. Again, I am reading this as “lossless stream sent” and “lossless stream received”.
Things get spicier when we move to Apple Music with The Chemical Brothers’ Loops of Fury EP getting the nod. The stream comes down from the cloud, to the iPhone insigating it and then onto the WiiM Pro Plus under my TV. To confirm, once again I turned the iPhone off and the music stopped. The transmitting iPhone’s ‘now playing’ screen clearly shows ‘Lossless’ but the WiiM Home’s ‘now playing’ screen tells us that it is only seeing the arrival 256kbps, a long way below the bitrate required for lossless audio carriage. This suggests, per Brother Thomas’s research, that the iPhone is converted the stream to AAC 256kbps before sending it onward.
If it weren’t for WiiM’s Home app, many of us would be none the wiser. Some of us might even refuse to believe what’s happening: seeing (not hearing) is believing. It matters not that the audible difference between ‘900kbps’ lossless and ‘256kbps’ lossy is neglible; the issue is Apple’s sleight of hand, presumably to tackle the number one complaint about (lossless) AirPlay 1 streams: audible drop outs.
OK — so what about Tidal? The Police have just issued a Deluxe Edition of Synchronicity and I’d not heard the song “Synchronicity II” for years. You can see on Tidal’s ‘now playing’ screen (running on the source iPhone on the left) that the file being sent is a 16bit/44.1kHz FLAC. The blue AirPlay logo above the Synchronicity Deluxe cover art confirms we are using AirPlay, not Tidal Connect. On the right, the WiiM Home app that monitors data arriving at the Pro Plus tells us it’s seeing ‘256kbps’ AAC. Lossy as charged! This finding contradicts Brother Thomas’s most recent update on the Tidal app’s AirPlay behaviour.
Time for another control: using Tidal Connect to send a 24bit/96kHz ‘MAX’ FLAC of Peter Gabriel’s “Come Talk To Me” direct from the cloud to the Pro Plus puts 2808kbps on the WiiM Home app’s ‘now playing’ screen. Moving Peter Gabriel back to AirPlay causes that number to drop to ‘256kbps’. That’s one-tenth the data throughput! Yikes.
This article will undoubtedly trigger the whatabouters: Whatabout Qobuz? Whatabout Amazon Music? I can’t cover every scenario. I pay for Spotify, SoundCloud, Tidal and Apple Music. That’s enough for one man…and it’s enough for most of the Darko.Audio readership. Our most recent ‘Which music streaming service?’ poll saw Tidal and Apple Music cover 69% of voters. Qobuz clocked in at 18% and Amazon Music at 9%.
I highly doubt that Qobuz and Amazon Music will forward audio to AirPlay 2 endpoints (like the WiiM Pro Plus) any differently than Tidal and Apple Music — but I could be wrong. Perhaps it’s time for you to go to work!
The conclusion remains that most streaming service apps running on an iPhone (or iPad) will send their output losslessly to an AirPlay 1 endpoint but will re-encode the incoming stream to 256kbps AAC before sending it to an AirPlay 2 endpoint. Plexamp shows us that it doesn’t have to be this way. (Roon isn’t part of this discussion as the audio doesn’t journey through the iPhone).
And before anyone hollers “Whatabout Chromecast?”, it doesn’t suffer AirPlay 2’s lossy rewrite but it isn’t gapless.
*[Footnote 1] I remain hazy on how Shairport deployment squares itself with Apple’s hardware certification process.
