Facebook360's audio solution allows for a scene relative ambisonic signal to be played synchronously with a head locked stereo stem. The Dolby Atmos Production Suite in VR mode allows a user to output compatible signals without costly remixing for delivery to FB360 platforms. We will need to configure the renderer to output the following Rerenders:
- Scene Relative B-Format
- Head Relative Stereo/Binaural
- All Beds Stereo/Binaural
In Dolby's VR workflows all Beds are classed as Head Relative sources meaning they will be statically rendered in the users experience regardless of where they are looking, this is useful for music score that might already be mixed in 7.1 for example. We therefore need two rerenders to create the final output, the first is for our dynamically controlled (via automation) head relative objects and another for All beds.
In this example I have set the Head Objects to be a 2.0 stereo rerender but the HeadBed to be Binaural, this is just to demonstrate that you can select either depending on the sonic effect that you would like to achieve.
The Production suite is able to output in either FuMa or AmbiX flavors of B-format, similarly FB360 Spatialiser is able to ingest either format. Providing that you match formats then the result will be the same but be careful not to mix FuMa output with AmbiX input as the soundfield will not play correctly.
In Pro Tools we will create Auxiliary channels to match the Renderer Output configuration.
- Quad Auxiliary
- 2 x Stereo Auxiliary
On the Quad we will instantiate a Multi Mono instance of the Dolby Renderer Return plugin.
We then need to Unlink the channels of the plugin so that they can each be set to a different rerender channel. You do this by clicking the chain link in the top right hand corner above the L chiclet and selecting Re-render channel 1, then switching to Right channel and setting to 2 or whatever matches the output of your Renderer configuration page.
Once we have done this we will instantiate the FB360 Spatialiser plugin from the Multichannel plugin menu (you may get a message about Outputs changing from Pro Tools, you can ignore this).
Notice the Input format can be specified here, make sure to select the appropriate B-format configuration.
On the two stereo auxiliaries that we created you should now instantiate a Multi Mono Dolby Renderer Return plugin on each, unlink and assign channels as we did on the B-format above.
We then follow Facebooks recommended routing. The B-format channel should then be routed to a bus called FB360 3D Master this is where all Scene Relative sound sources end up in Facebooks platform.
The two stereo Auxiliaries route straight out to a stereo bus in this case a subpath of a bus called FBDM (Facebook Downmix) and as you can see from the routing image below is also where the 3D Master stem ends up.
Notice that this stereo subpath is reconfigured so the Right channel of the subpath is on the Center channel of the FBDM 7.1 bus.
Once configured correctly you'll be able to dynamically route object audio between the FB360 3D Master and the headlock stereo and send audio directly to the headlock stereo from bed channels.
This can be seen in the attached GIF.
The session used in this walkthrough is also attached for your reference along with an IO configuration for the Production Suite.