How to deliver a Dolby Atmos Music project
Delivering an Atmos project is not a matter of exporting a file. Here is the reference format, the checks it must pass, and what changes for an album.
The reference format: ADM BWF
For a Dolby Atmos Music delivery, the reference format is ADM BWF. For Atmos deliveries intended for Apple Music, Apple asks in particular for a BWF ADM file in 24 bit LPCM / 48 kHz, synchronised with the corresponding stereo master.
Apple also imposes requirements on integrated loudness and True Peak, and asks that each track of an album be delivered as an individual ADM BWF file.
Delivering is not exporting
Delivering an Atmos project is not simply a matter of exporting a file. The master must be verified in the Dolby Atmos Renderer. Here is what we check.
| What we verify | Why |
|---|---|
| Duration and sample rate | an offset or a non-compliant rate gets the delivery rejected |
| Loudness and True Peak | platform requirements, and the risk of distortion on transcoding |
| Downmix settings | what becomes of the mix when the listener does not have the target system |
| Binaural metadata | they determine the headphone render, where most people will listen |
| Overall consistency | the file must behave like the mix approved in the room |
Dolby also recommends carrying out a listening check both on a speaker system and on headphones via the binaural render, then verifying how the master behaves on the various playback systems concerned.
The album case
For an album, each track must be delivered as a separate ADM BWF, while maintaining overall consistency across the tracks. The two requirements go together: separate files, but a set that holds up.
Specifications depend on the destination
Exact specifications may depend on the distributor, the label or the destination platform. We therefore always check the requirements that apply to the final workflow. Dolby itself notes that delivery settings can vary by service or broadcaster.
If you cannot decode an ADM, we can supply a binaural file and an MP4 JOC, so that you can listen to and approve your master.
On the limits of working on headphones upstream of this delivery, see can you mix Dolby Atmos on headphones.
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