Dolby Atmos/Spatial Audio or 5.1 Audio over Bluetooth

General
1

As I understand it, Infuse relies upon Apple’s Spatial Audio tech stack when working with Dolby Atmos over Bluetooth. Does that differ according to what platform the video is being played on? The “compatible devices” support page that Infuse’s own Dolby Atmos page links out to only talks about devices with “Personalized Spatial Audio with Head Tracking”. Plus, the page only talks about Apple TV. I want to know if the capabilities are different if I’m playing it over USB-C to HDMI but using Bluetooth headphones for audio.

There are Beats headphones that do support plain-vanilla “Spatial Audio” without the special head tracking bit. Would those headphones work with Infuse faithfully reproducing Dolby Atmos from E-AC3 tracks? There’s no consumer-facing toggle that lets you turn Spatial Audio on and/or off on those models (unlike the models that do support Head Tracking), so how would one go about verifying that Dolby Atmos Object data is being faithfully reproduced? Are multi-channel audio tracks (like AAC 5.1) that don’t use the E-AC3 codec downmixed to stereo as well over Bluetooth?

Secondly, what happens if you’re using a pair of bluetooth headphones that don’t support Spatial Audio? Is any audio track with more than 2 channels simply downmixed to stereo? I know that over HDMI, Infuse on Apple TV will convert DTS HD-MA and TrueHD to multi-channel LPCM? How does Infuse navigate that over bluetooth on iPad/iOS devices? Does Infuse support uncommon channel configurations over bluetooth like 3.0/4.0 that some DTS HD-MA tracks can have? If it’s not downsampled to 2.0 stereo, are there any specific channels that get discarded (like height channels etc) over Bluetooth transmission?

Finally, what about wired Audio? Apple Music supports Dolby Atmos on any Apple or Beats Headphones + any wired headphones. Can Infuse extend that same capability?

Thank you for all your work on this beautiful app!

1 Like
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This is the compatible devices support page that Infuse’s page links out to.

3

It looks like Apple has recently rewritten that guide, but here is a screenshot from the original version which lists the compatible devices.

Screenshot 2025-04-08 at 8.03.17 AM
Screenshot 2025-04-08 at 8.03.17 AM1680×982 86.7 KB

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Hi, @james! Thank you for responding! So, if you look here, all three say they support “Spatial Audio”, with the little caveat that:
“Compatible hardware and software required. Works with compatible content in supported apps. Not all content available in Dolby Atmos.”

Would any of these work for Atmos over Bluetooth through Infuse?

It seems the guide you initially linked to and the current one both are geared towards “Personalized Spatial Audio with Head Tracking”. Is the Personalized and Head Tracking bit essential for the reproduction of Dolby Atmos through Spatial Audio in Infuse? And what about wired audio? And is multi-channel audio sent as multi-channel over Bluetooth or is it downmixed to Stereo if Spatial Audio isn’t supported on the connected earphones?

5

This is more or less determined by Apple.

In a nutshell, if the system says there is a Spatial Audio (or multichannel) audio pipeline available then Infuse will use it. If not, then Infuse will provide stereo.

I can’t say whether there are any non-Apple headphones that Apple would recognize as supported.

6

Thank you! Is there a way for us as consumers to test if Spatial Audio is being used for Dolby Atmos or multi-channel audio? Maybe a way to generate logs and read them to see if Infuse is sending audio as Spatial Audio? Maybe a test file that tells you how the audio should sound (where the object should sound from) if Spatial Audio and Dolby Atmos are being used?