Apple Spatial Audio Down-mixing

  • 13 August 2023
  • 3 replies

I have read that Apple down-mixes Dolby Atmos so that it can be delivered via Apple Music using AAC 256kbps in stereo i.e. they are simulating Dolby Atmos in stereo and I guess this is why they call it Spatial Audio? 

Does anyone know if this is correct, or whether Spatial Audio is in fact being delivered using the Dolby Digital Plus codec without down-mixing.  

Long story short I am trying to figure out whether Apple's Spatial Audio (and Amazon Music Unlimited I guess) is using all of the Era 300’s drivers or just simulating through stereo when playing via S2 app.


Best answer by GuitarSuperstar 13 August 2023, 23:10

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3 replies

Userlevel 7

The Spatial Audio tracks on Apple Music are mixed in Dolby Atmos and delivered via Dolby Digital Plus for streaming. The non-Spatial Audio tracks are mixed in stereo. Typically a Dolby Atmos audio track is created as a 7.1.4 mix. But since the Era 300 is just a standalone speaker, it is designed to take a Dolby Atmos mix and fully utilize all of its drivers to reproduce the Dolby Atmos audio experience.

@GuitarSuperstar that’s great info, thanks. Do you know what bitrate it’s streamed at, and whether there’s any quality difference between Apple’s Spatial Audio and Amazon Music Unlimited’s Dolby Atmos when played via the S2 app?

Userlevel 7

I’ve read that Dolby Atmos music from Apple Music is streamed at around 750 kbps.

I’m not sure if there is much of a difference in quality between Apple Music and Amazon Music Unlimited. Apple Music will probably have a larger selection of Atmos music though.