Have Apple F***ed Atmos?

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If you’ve recently listened to music on an Apple ear-mounted device with Spatial Audio turned on, you’d be forgiven for thinking this Dolby Atmos malarkey is an absolute sack of sh*t and that we should all just stick with stereo.

A few short years ago, binaural versions of Dolby Atmos mixes intended for listening on headphones sounded a bit like the stereo mix, but with a poorly chosen, vaguely immersive reverb. To quote myself from back then, it sounded like the stereo mix in a large bin. 

Then, things started to get good.

I vividly remember switching to headphones to check the Dolby binaural version of some mixes we'd completed for a regular Atmos client. I was so convinced I’d forgotten to mute the speakers that I took them off again and was met with silence! The binaural render was getting that close to faithfully reproducing what we hear in the studio on a multi-channel speaker system. Hurrah!

And if you’re listening on any headphones, on a platform that uses Dolby’s latest AC-4 IMS codec (that’s Audio Codec-4, IMmersive Stereo if you're interested), namely Tidal or Amazon Music, it sounds pretty good—especially with objects placed behind the listener. It's truly immersive audio for everyone. Hurrah!

Everyone apart from Apple users, it seems. 

If you take a listen on your trusty Apple device with AirPods Pro or Max, it sounds like they’ve remastered the stereo mix using a wax cylinder as the technical reference, then rolled it in mud. It's, frankly, appalling, and has taken a huge step backwards. It’s bad enough that our clients call to ask what the actual f**k we’ve done to their carefully crafted art once it’s released on Apple Music. Boo!

So, what's going on?

Well, Apple don’t use AC-4 IMS. They use a lossy, detail-stripping codec called DD+JOC (that’s Dolby Digital Plus Joint Object Coding if you really care) and then push it through their own Spatial Audio algorithm. Why? We think it’s so they can better utilise their head-tracking functionality.

This isn’t a bad thing, and it actually mimics how the human perception of sound directionality works. If we’re being stalked by a bear in the forest and aren’t exactly sure where the gentle sound of heavy breathing and huge paws crushing twigs is coming from, our brain automatically triggers a slight head movement, enabling far more directional accuracy. This, combined with reflections from nearby surfaces - trees in this case - means we can reliably determine in which direction to run, or which side of the nearest tree to hide behind if we’re too late for that. It's a basic survival instinct and a true miracle of evolution.

And other animals have an even more developed system. FlopCat can rotate his ears independently of each other, as can dogs, and many other animals. This enhances their ability to locate sounds and can not only be used to effectively escape danger, but also hone in on prey. When Flop is stalking a rodent in a hedgerow you can actually see his ears focus in on the precise location of the poor, doomed creature.

But does this matter for music?

Well, yes and no.

While the head-tracking functionality can better "sell" the immersive effect to our brains, I don’t want the band we’ve intentionally positioned at the front of the mix to suddenly be in my right ear because I turned my head to look out the train window. And I certainly don't want a spatially convincing version of my mix that sounds like it’s being audibly compressed by the streaming platform and is trying to reach my ears from a tin can on Mars.

So, what's the answer?

Apple - stop this nonsense and respect the intention and the mix that we, the labels, and the artists have signed off on - what you're effectively doing is akin to Netflix recolouring a movie based on what they think it should look like!

We, and many others (including Dolby), have been putting pressure on Apple to just adopt the far better AC-4 IMS codec, like everyone else has. 

But if you're working in Dolby Atmos and are concerned about this, we'd encourage you to just ignore what Apple is doing for the moment. Be thankful that the carefully crafted ADM file you sent to the label is being decoded in real-time on the device it's playing on, and so can (and will) change over time—hopefully for the better! Then, send the artist the binaural version from the Dolby Atmos Renderer for them to approve on headphones, and explain to them why they should ignore Apple as well.

Is this the death knell for Dolby Atmos?

Absolutely not. This is still an evolving format, with the 7.1.4 and above speaker version being the gold standard to work with. That's what the codecs are trying to replicate and, in the case of AC4-IMS at least, doing a great job of. We at PDP Towers are still very much in love with the format and truly believe it is the future of music.

How many times have you recorded an acoustic guitar and struggled to get it to sound half as good as it does when you listen in the room? You save for a better microphone, better preamps, a better guitar, and work hard to build a better-sounding room. I've had that struggle for decades, and since we’ve been working in Dolby Atmos, it’s become clearly apparent to me that it's the playback format (ie stereo) that's at fault, not the recording chain.

A well-recorded instrument in a good-sounding room with an immersive microphone array can truly sound like the musician is right there in the room with you on a good Atmos speaker system—or on a good pair of headphones listening to Dolby’s binaural render. It's not the fidelity you were missing; it's the sense of space, height, and immersion. It’s the way our ears work!

See you next week.

Lots of love,

Mark