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Dolby Atmos music mixing terminology explained by Mix Engineer John Hanes

DavidMcRoy

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Hanes wrote this on Gearspace, and it’s a Must Read:

“First, we need to get terminology straight. We can't use binaural and stereo interchangeably. Binaural is not stereo; it is a 2-channel downmix to be delivered to Headphones.

“So the process is to do the mix, record it into the Dolby Renderer.

“This captures the entire Atmos mix, which will be essentially a .WAV file with 12 to xxx tracks of audio. 12 Bed tracks, plus a track for each object. I'll generally use up to 20 object tracks, so that would be a .WAV file that has 32 tracks. The renderer also captures the Object metadata which tells the decoder where to pan objects.

“Then inside the renderer, there are options to create the Binaural Downmix. Basically can set each bed track and object as Off, Near, Mid, Far. This is also encoded into the ADM-BWV file that is sent out for delivery.

“At the decode end, where you are listening, your decoder will know if you are listening on Headphones and decode and dowmix to binaural with the specified settings, or know if you are listening on a multichannel speaker system where is will decode and send beds and objects to the speakers available to it. So if you have a 5.1 speaker system, the decoder will know and playback to the appropriate speakers. If you have a 9.2.6 speaker system, it will also know that and will playback.

“So one file is delivered and streamed that can be decoded to whichever listening environment is appropriate.”

You can find it one page 3 in this forum thread:

https://gearspace.com/board/new-pro...ll-bring-lossless-audio-entire-catalog-3.html
 
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DavidMcRoy

DavidMcRoy

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Here are my takeaways—answers, presumptions and further questions—regarding the nature of Dolby Atmos signal/file hierarchy as they relate to home playback of Dolby Atmos music mixes provided through streaming services such as Apple Music, Tidal, etc., based on what I’ve read from Apple itself and from mix engineer John Hanes (above):

(1) When listening to Dolby Atmos, the mix you hear is determined by what equipment you’re using.

(2) Hanes says there is a primary Dolby Atmos mix designed for multichannel playback in an immersive home theater-type environment, and a particular version will be delivered depending on how many speakers you are using. Hanes says the first mix he creates is for 7.1.4 channels. He mixes in a 7.1.4 control room, and my playback environment happens to also be a 7.1.4 system. Apple indicates that currently an Apple TV4K running tvOS 14.6 or higher is required to deliver such a signal from Apple Music. If fewer speakers are available, for example a 2.1.2 system or a 4.1.2 system, etc., appropriate downmixes will be provided by the Apple TV4K. I do not know whether the downmix hierarchy goes down to 2.0 speakers.

(3) After the Dolby Atmos 7.1.4 mix is created from speaker playback, that file is fed to a Dolby Renderer which creates a binaural downmix that’s exclusively for playback on headphones and in-ear monitors (earbuds.) The Dolby Renderer apparently has some degree of control available to the mixing engineer, such as panning, depth, loudness, etc. of specifics sound objects.

(4) I presume that a determination is made as to whether you’re using the headphone jack or not to distinguish between downmixes for headphones vs. speakers? I don’t know. I also don’t know how peripheral devices like Homepods fit into the scheme.

(5) Hanes has stated that feeding a binaural mix into 2 stereo speakers is liable to sound strange, since it wasn’t created for that’s scenario. It can be anticipated that some listeners (like many of us here) will feed whatever the file is that’s being sent from an iPhone or iPad Lightning port, to an outboard DAC/headphone amplifier to feed a set of headphones. Is this still a binaural downmix? Presumably it is. If so, then it’s unsuitable for 2 speaker stereo playback, and one should use the original 2-channel stereo mix, not any Dolby Atmos mix.

Hanes has said what I presumed, that across the industry mixing music for Dolby Atmos is kind of in its infancy, and some of the mixes are going to be better than others. Having lived with Dolby Atmos over a 7.1.4 system for movie and TV soundtracks, I know how well the system can work, and I hate to see new users getting bad first impressions because of poor implementation at any part of the chain, production, distribution or playback.
 
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markanini

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IMO it's largely a device to extract licensing fees from manufacturers and consumers. I'm saying so because I know of the tools of in the trade to create space and distance, even elevation, on traditional stereophonic delivery formats. Finally the incentive to lock your audience to exclusive systems isn't there so don't expect a wide adoption.
 
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DavidMcRoy

DavidMcRoy

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IMO it's largely a device to extract licensing fees from manufacturers and consumers. I'm saying so because I know of the tools of in the trade to create space and distance, even elevation, on traditional stereophonic delivery formats. Finally the incentive to lock your audience to exclusive systems isn't there so don't expect a wide adoption.

I don’t have any comment about profit motivation theories. I’m only concerned with the practical and successful implementation of a technology that has become familiar to me and which I think deserves more widespread availability. The various “versions” of Dolby Atmos for everything from immersive speaker arrays to earbuds strive to create a larger palette onto which a sonic picture can be painted. The technology doesn’t threaten the implementation of alternative methods of sound reproduction, it’s just another tool. You remain free to advocate for and practice your own techniques as you see fit. The art and science of sound reproduction are a part of the entertainment industry, within which a profit motive will often be a consideration.
 

amirm

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IMO it's largely a device to extract licensing fees from manufacturers and consumers. I'm saying so because I know of the tools of in the trade to create space and distance, even elevation, on traditional stereophonic delivery formats. Finally the incentive to lock your audience to exclusive systems isn't there so don't expect a wide adoption.
It is true that Dolby lives to make royalties from everything they can. That aside, authoring spatial sound is always superior to extracting them from lower number of channels.
 

Soundmixer

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“This captures the entire Atmos mix, which will be essentially a .WAV file with 12 to xxx tracks of audio. 12 Bed tracks, plus a track for each object. I'll generally use up to 20 object tracks, so that would be a .WAV file that has 32 tracks. The renderer also captures the Object metadata which tells the decoder where to pan objects.
He must be using the Atmos ISF format (gaming format), as that is the only one that allows 12-bed tracks plus objects. Cinema Atmos uses a 9.1 bed plus objects, and the Atmos format for HT only uses a single bed channel(LFE) plus up to 16 dynamic objects.
 

Soundmixer

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IMO it's largely a device to extract licensing fees from manufacturers and consumers. I'm saying so because I know of the tools of in the trade to create space and distance, even elevation, on traditional stereophonic delivery formats. Finally the incentive to lock your audience to exclusive systems isn't there so don't expect a wide adoption.
You may have the tools (XYZ panner plug-in), but you don't have the integrated processing software and streamlined workflow that Atmos and X have.
 
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