I need to clarify some questions about the signal Flow in ATMOS related in post-production ambients: 1.- Do i need always a RMU unit (Separated Computer with the Atmos Mastering Suite) to encode the ATMOS file? or is possible to make in the same Protools Computer with internal routing? 2.- What happen with the ATMOS file? where it is added or summed with the final Video File? Another Dolby Suite? or a Video Editing software? 3.- Which is the sync method of the 2 Computers (Protools & RMU)? SMPTE by LTC? EUCON or another protocol?
Hi, Some big topics here.
1. The Home Theater Renderer software is what records (or print masters) an Atmos master which contains audio and panning/positional metadata from your DAW. This creates a .atmos master file set.
The Home Theater Renderer can run on dedicated hardware as the Dolby Atmos Mastering Suite or locally on the DAW workstation as the Dolby Atmos Production Suite. For complex content it is recommended to use approved dedicated hardware with the Mastering Suite. This is available configured from an authorized Dolby dealer.
The Production Suite was design to function primarily as an editorial and sound design tool. While it be used to print master it can also over-tax your CPU/drives which can in turn cause problems with the master file. When using the Production Suite with Pro Tools internal routing to the Renderer is via send/return plugins are used which are pre-delay compensation which is inconvenient. A core audio emulator name the Dolby Audio Bridge can be used which is post delay compensation but this is limited to 32 tracks of I/O with Pro Tools.
The Renderer can also export the .atmos master file set as ADM BWF or IAB MXF
2. Once you have a Dolby Atmos master file recorded it can be encoded to Dolby Digital Plus with Atmos Content (for streaming) or to Dolby TrueHD (for Blu-Ray). The master files used for encoding can be .atmos, or ADM.wav or IAB.mxf exported from the Renderer.
The tool used for Dolby Digital Plus with Atmos Content or Dolby TrueHD is the Dolby Media Producer Suite. There is also an enterprise command line tool available name the Dolby Encoding Engine for cloud and distributed encoding of Dolby Digital Plus with Atmos Content.
For streaming purposes the Atmos audio (Dolby Digital Plus with Atmos content - .ec3) is multiplexed with compressed video (.h264/.h265) to create an .mp4 which is segmented for streaming services delivery. Dolby Encoding Engine can do this and there is also a command line open source mp4 multiplexer that Dolby has made available on Github.
For Blu-Ray the Atmos audio (Dolby TrueHD - .mlp) is authored with compressed video using the Scenarist or Blueprint authoring applications.
Future workflows will enable the importation of IAB.mxf into NLEs to create IMF for delivery to streaming services.
3. Synchronization between the DAW and Rendering and Mastering Workstation is via LTC. When using a Rendering and Mastering Workstation with MADI I/O, LTC is input directly to a sync daughterboard. When using a Rendering and Mastering Workstation with Dante I/O the LTC occupies a Dante channel.
I hope this helps.
There is more information here:
Also please have a look at the knowledge base for both the Dolby Atmos Mastering Suite and Dolby Atmos Production Suite here:
Adam at Dolby
short question: Is there any advantage in having the .atmos master file set as an archive master in to archiving an ADM WAV master?
Not really. It is personal preference and up to any given facility or company to decide what works best for them.
Archiving a .atmos master file set means keeping four files around in a folder so perhaps more opportunity to misplace one. On the positive they can be opened up in the Renderer for punch-in operations and rewriting downmix metadata without conversion.
Archiving a ADM .wav means only keeping track of a single file. They can be readily imported as session data into Pro Tools. The only downside is that these would need to be convert back to .atmos if you needed to perform a punch-in from the original Pro Tools session. There is however the extra step of exporting an ADM .wav for export.
On balance I think ADM .wav is a better choice for deep storage.
Great, thanks for the info Adam!
Adam, short follow up question: Is there a way to tell from the metadata that an ADM file is a Dolby Atmos file? We're trying to build automatic workflows into our MAM system that need to tell if a file is a Dolby Atmos file or not.
We didn't find anything yet that can be used as a unique identifier.
Hi Sebastian, It depends how intelligent you need to the system to be. The easiest thing to do would be to look at the channel count of the .wav. Do you have any interleaved .wav if your workflow that go beyond 6 channels (5.1) or 8 channels (7.1 or 5.1+2)? If not interrogating the channel count with MediaInfo for being more than 6 channels might be sufficient. If not I'll need to get back to you. There is an ADM validation component as part of our SIDKs but that might be overkill for your implementation. I will get back to you about other potential solutions.
There is more information of what you can use to identify ADM Wav and the components that would identify it as Dolby Atmos.
The ADM atmos profile doc can be downloaded from here: https://developer.dolby.com/technology/dolby-atmos/adm-atmos-profile/
The includes looking for AXML as specified here: https://tech.ebu.ch/docs/tech/tech3285s5.pdf (see section 4.2) and also the Dolby specific dbms chunk. This document is currently in review but will be posted to this site when it is available.
Hope this helps.