[bigshot]

Maybe they will make another dongle to plug into the headphones! They like dongles there at Apple.

 

[bigshot]

I figured out a way to toggle Spacial Audio on and off. It appears to have nothing to do with the multichannel mix. It's just a DSP added to a regular stereo mix. It adds a tiny bit of phasey reverb, like the sound of a small room with a concrete floor. It also boosts the bass, maybe with some sort of additional phase shift, and it boosts the overall volume level (natch!) I don't see why this is limited to Atmos tracks on certain streaming services. It seems like it could be applied to any kind of stereo audio.

 

[Davesrose]

I figured out a way to toggle Spacial Audio on and off. It appears to have nothing to do with the multichannel mix. It's just a DSP added to a regular stereo mix. It adds a tiny bit of phasey reverb, like the sound of a small room with a concrete floor. It also boosts the bass, maybe with some sort of additional phase shift, and it boosts the overall volume level (natch!) I don't see why this is limited to Atmos tracks on certain streaming services. It seems like it could be applied to any kind of stereo audio.

Interestingly I had a friend ask me about headphones for Dolby Atmos for watching movies off an OLED TV (since he’s scared about having speakers with active kids around). My experience with Dolby Atmos with Windows is that it’s great for passing Atmos tracks to my 7.1.4 speakers….but actual positional sound with headphones seem limited to sources that are specifically Atmos Headphone (the Atmos Windows filter with stereo just seems to add some bass to my ears). I did look up Apple spacial audio for AiPods/Max. Oddly, it supports Dolby Atmos with the Apple TV app (for movies encoded in Atmos) on iOS (iPhone and iPad), but movies are not supported with the Apple TV 4K (say what???). Apple does support positional audio with AirPods on Apple TV 4K with the music app. If you’re looking for positional audio with Dolby Atmos for movies, it seems the best is the JVC EXOFIELD system (not as limiting with movies as Apple). It’s not cheap, but apparently it has a receiver base and does model your ear for a custom HRTF. I haven’t read a review about how it is with a stereo source….but with a regular Atmos track, it is supposed to have convincing 7.4 positioning.

 

[bigshot]

I don't believe you can have convincing surround sound without custom HRTF calibration. People are calling Apple's Spatial Audio "surround" and it clearly isn't. I don't think most people know what multichannel actually sounds like.

Dolby plays it close to the chest with this stuff. My suspicion is that all the spatial stuff is a DSP running on the phone itself. The audio track itself is a normal stereo fold down. AirPods Max only support stereo, so the signal being fed to them has to be something like Dolby Stereo, or more likely just processed normal stereo.

 

[sander99]

Some quotes related to the JVC Exofield:

The JVC XP-EXT1 is not a generic HRTF based system.
Originally it also worked with what basicily is a PRIR measurement. But now they do it differently. From a video somewhere I understood it as follows: Now the headphones have 4 microphones built in each cup. In the calibration process they measure how the test signals from the drivers end up at the different microphones. Now from this result they don't calculate the HRTF or room impulse responses - maybe that isn't even possible - but they compare the result with results from a lot of different people in a database, and next they choose the HRTF or room impulse responses from the person in the database that comes closest. (Reminds me of the approach to compare photographs of the ears with photographs in a large database and pick the HRTF of the best matching person.)

... I was 63 when I ordered. I may be deaf (or dead) by the time I get my A16. In the meanwhile I bought a JVC EP-EXT1 - it's fun but no A16.

And, did the JVC put the sound far outside your head like real speakers or was the effect limited in some way?
(Of course Camano's answer won't give any guarentees for other people, because for example different people's brains can react very differently to the absence of headtracking, for some it spoils the effect, for some it doesn't seem to matter. But I am just curious.)

The answer for me is no. I've run the calibration a dozen times and they all sound about the same. Sound placement is great, but it all seems to be right next to my head unless some room sound was recorded on tthe soundtrack. There is no sense of a virtual room. It is firmware upgradable so this might get better, or it might just be me. Atmos placement is good. Head tracking would probably help with a sense of room.

Is it better than an A16 - definitely not. Is it better than nothing while I wait (...and wait...) - definitely yes.

(PS - I would have happily paid Smyth what I paid for the JVC to expedite shipment of my A16, but that would have been only 1/3 of what they're actually asking)

So from Camano's experience I conclude that the calibration process of the Exofield probably doesn't work as well as I had hoped, not as well as a Realiser PRIR+HPEQ measurement.
(Too strong a conclusion from one user's experience? I think maybe not because a good calibration process should make it work for everybody or most people.)
And with that it looses the main potential benefit - easier calibration without needing speakers - it would have over using Impulcifer to create a preset for HeSuVi. (Only you won't have Atmos and have to use the pc as your AV source with Impulcifer/HeSuVi. Both solutions don't have headtracking so no difference there.) The software is free, all you need is in-ear-mics and maybe an audio interface to connect them to a pc. And speakers to measure of course.

 

[Davesrose]

I don't believe you can have convincing surround sound without custom HRTF calibration. People are calling Apple's Spatial Audio "surround" and it clearly isn't. I don't think most people know what multichannel actually sounds like.

Dolby plays it close to the chest with this stuff. My suspicion is that all the spatial stuff is a DSP running on the phone itself. The audio track itself is a normal stereo fold down. AirPods Max only support stereo, so the signal being fed to them has to be something like Dolby Stereo, or more likely just processed normal stereo.

From what I can read, it’s not just stereo. All sources do specifically say that the spatial audio is with Dolby Atmos. So with convincing positional audio I’ve heard with headphones…..the first time I heard it was a Sennheiser Dolby Pro Logic processor which had you dial in parametric settings (based on your ear type). I do admit that when I’ve tried the Dolby Headphone examples with Dolby Atmos app on Windows, I have been blown away by how well it works (without any kind of active calibration) for sources that are specifically Atmos Headphone tracks. Stereo, or the more conventional 7.1 Atmos movie track doesn’t have any sense of positional audio when I try feeding them through any pair of headphones with the Dolby Windows filter, though. So the only time I’ve heard really convincing positional audio with headphones and Dolby Atmos is extremely limited scenarios. From what I can tell, the JVC headphones are the main ones that actually do take the common Atmos tracks (7.1 movies) to create the sound field based on HRTF.

https://www.apple.com/newsroom/2021/05/apple-music-announces-spatial-audio-and-lossless-audio/

 

[Davesrose]

So from Camano's experience I conclude that the calibration process of the Exofield probably doesn't work as well as I had hoped, not as well as a Realiser PRIR+HPEQ measurement.
(Too strong a conclusion from one user's experience? I think maybe not because a good calibration process should make it work for everybody or most people.)
And with that it looses the main potential benefit - easier calibration without needing speakers - it would have over using Impulcifer to create a preset for HeSuVi. (Only you won't have Atmos and have to use the pc as your AV source with Impulcifer/HeSuVi. Both solutions don't have headtracking so no difference there.) The software is free, all you need is in-ear-mics and maybe an audio interface to connect them to a pc. And speakers to measure of course.

My friend balked at the price of the JVC: I didn’t bring up the Realiser because he already indicated that he couldn’t fathom how much I spend on audio. I do think that JVC is gambling on a certain market: those that need an isolated system that brings 3D sound for movies (and optimized with Atmos sources), or folks that want more than just a sound bar. In todays age, that in itself might be limiting: I’m always floored that many YouTube reviews go on about how great sound bars or Apple HomePods sound. I’m thinking that with my stereo systems, my bookshelf speakers are going to sound much better than a pod. Then with my 7.1.4 speaker system that has full tower mains, full cabinet speakers, and nice controlled subwoofer……I’m never going to equate a sound bar as “wow, this can replace my speaker system”.

 

[bigshot]

From what I can read, it’s not just stereo. All sources do specifically say that the spatial audio is with Dolby Atmos.

I think Dolby is playing fast and loose with the definition of Atmos. Switching back and forth to toggle Spacial Audio on and off, the mix is identical. The only differences are things that a DSP would modify on a stereo source. Is an iPhone even able to pass through Atmos sound?

I did a comparison of a David Attenborough special on AppleTV (or was it HBO Max? Don't remember now.) with a David Attenborough special on Netflix with Atmos sound (but not compatible with Spacial Audio) and there was no difference in the placement of sound in space. Both were a straight line through the ears. No front/rear depth at all. They sounded identical in sound quality.

I really think this is targeted at an audience who has never heard a multichannel speaker system and is impressed by phase/reverb effects like Pink Floyd.

 

[MayaTlab]

I think Dolby is playing fast and loose with the definition of Atmos. Switching back and forth to toggle Spacial Audio on and off, the mix is identical. The only differences are things that a DSP would modify on a stereo source. Is an iPhone even able to pass through Atmos sound?

https://learning.dolby.com/hc/en-us/articles/360052744252-Module-1-2-Beyond-Multichannel-Audio-

TLDR : it's not stereo, but I don't think that we know exactly how Apple transposes the master file into deliverable formats and at which point. The master file (all 128 beds / objects) is probably too large to be streamed.
That being said, since when Apple streams a Dolby Atmos track to an iPhone, they don't know exactly on which device it's going to be played, and whether this device is a pair of headphones, stereo speakers, etc... the deliverable must have a decent number of beds (and objects ?) to work with. It's probably then transposed on the device (the phone in that case) into something that can work on the device it's being played on.

 

[bigshot]

I don't think the iPhone is doing object based mixes or spatial coding. I think it is just applying a DSP with a reverb and EQ to a stereo signal.

 

[MayaTlab]

I don't think the iPhone is doing object based mixes or spatial coding. I think it is just applying a DSP with a reverb and EQ to a stereo signal.

I don't think that it's receiving 128 beds / objects to work with for sure, but I don't think that it's receiving a stereo format either.

 

[bigshot]

If they are breaking down 5 channels it's still incredibly underwhelming. I am listening to this stuff and it is NOT 3D. It's phase tricks like on Pink Floyd albums. I have DSPs on my AVR that sound more dimensional than that, but that is probably because you can actually get depth with a multichannel speaker system. Not with headphones without serious bandwidth and processing and calibration to personal HRTF.

Can the iPhone's internal sound process multichannel? I know the DAC in the AirPods Max can't. That can't even do lossless. I really think this is just a DSP on top of stereo.

 

[MayaTlab]

If they are breaking down 5 channels it's still incredibly underwhelming. I am listening to this stuff and it is NOT 3D.

That could be caused by a lot more factors than what the deliverable format is.

Can the iPhone's DAC process multichannel? I know the DAC in the AirPods Max can't. That can't even do lossless.

Dolby Atmos isn't just a multi-channel format. Cf link above.
DACs don't process multichannel audio, they just convert a digital signal to an analog one. The conversion happens in the digital domain.
The APM's wireless internal chain is simply meant to process a bluetooth stereo feed from your device into an analog signal. So the transposition from a Dolby Atmos streaming deliverable to stereo happens at least before that point (most likely on your device since it's the one that can know which device the sound is being played back on).

 

[bigshot]

That is my question. Can the iPhone handle multichannel audio? Is there any other app or application that runs multichannel sound through an iPhone? Can you stream Netflix on your phone and cast it to your AVR and listen in multichannel Atmos on speakers? I've never tried to do that, so I don't know.

 

[MayaTlab]

That is my question. Can the iPhone handle multichannel audio? Is there any other app or application that runs multichannel sound through an iPhone? Can you stream Netflix on your phone and cast it to your AVR and listen in multichannel Atmos on speakers? I've never tried to do that, so I don't know.

I see no reason for it to be unable to transpose a format with multi-channel audio (or object base audio) to stereo. It's a software thing in the digital domain.
What's certain however is that the Apple TV's Dolby Atmos implementation in videos works with Dolby Atmos receivers and multiple channels, so in that case it's quite obvious that Apple's delivery format for Dolby isn't stereo.