Topics covered in this article:
- Single composite Bed output
- Multiple Bed output
- Bed tracks for reverb returns and other plug-ins
- Stereo Object tracks
- Object/Bus toggle automation
The first ten inputs to the Renderer are dedicated to Bed audio input. Beds are configured in the I/O setup of the DAW and in the Renderer Input Configuration Window. The Renderer defaults to a single 7.1.2 Bed; however, a smaller Bed width can be used.
Alternatively, Objects alone can be used (the first 10 channels will still be reserved for Bed audio), or the DAW and the Renderer can be configured to use multiple Beds to facilitate a traditional stem-based workflow.
The decision on whether to use a single composite Bed and leave 118 Renderer inputs available for Object audio, or to use multiple Beds with fewer Renderer inputs available for Object audio, is dependent on the mixer’s preferences, the content and workflow considerations. Multiple Bed workflows are use primarily for post production workflows.
For some projects and workflows, the flexibility of having more inputs available for Objects is outweighed by the inefficiency of having to perform multiple mastering passes (selectively muting tracks in the DAW) in order to derive channel-based stem re-renders. For some projects and workflows, the simplicity of a single Bed and the availability of 118 Objects makes sense.
Single Composite Bed Output
If the decision is made to go with a single composite 7.1.2 Bed (as per the default Renderer Input Configuration and supplied templates), this does not restrict the flexibility to work with stems within the DAW. As long as audio leaves the DAW as a combined 7.1.2 output routed to the first ten Renderer inputs, there are no restrictions on how the DAW session is laid out and routed internally. For example, each stem may be assigned to a 7.1.2 aux input track with audio tracks of any width feeding each stem as needed. These may be summed to a single 7.1.2 aux input before output if bus processing is desired, or may be bussed to the main 7.1.2 output for summing.
Bed Tracks for Reverb Returns and Other Plug-ins
There are a multitude of different reverbs and plug-ins for use with 7.0.2 and 7.1.2 track widths in a DAW.
When working in Dolby Atmos, multichannel reverbs can be shared between multichannel Bed tracks and Object tracks using similar send-and-return routing to that used in traditional surround formats. These can return to their own 7.1.2 aux inputs bussed to the composite Bed output, a stem output, or their own Bed output.
If the Object track’s reverb can work effectively with generalized pan positioning, then a 7.1.2 return to the appropriate Bed is usually the best option. An added benefit of this configuration is that both Bed tracks and Object tracks can share the same reverb using a traditional send-and-return configuration, although it does mean that the Object’s reverb will be present in the Bed without the dry source Object present. A 7.1.2 re-render from the Renderer is therefore required in order to provide a complete stem, with Object and Object reverb rendered and present.
To apply reverb to an Object track and return the reverb to a 7.1.2 Bed:
- Create a 7.1.2 aux input track and insert the desired reverb plug-in on the track.
- Create a new 7.1.2 bus in I/O Setup for use as a reverb send path, and allocate this as the input to the aux input track. Route the output of the aux input track back to sum with the appropriate Bed track, such as the main 7.1.2 Bed or a 7.1.2 stem/group Bed.
- On the Object track, create a send to the 7.1.2 aux input track. The send fader can then be used effectively as a wet/dry level control. In most cases, you’ll want to enable Follow Main Pan (or FMP) in the send’s panner so that the Object panning metadata will be applied to the send pan position.
Using Stereo Tracks for Objects
When creating a Dolby Atmos mix, stereo sources can be assigned to stereo Objects. This can be somewhat confusing to configure, as the Renderer treats all Object inputs as mono. In addition, the Pro Tools I/O Setup only supports bus mapping to mono Object paths. Subpaths are used to combine two mono Objects into a single stereo Object output path. If using the stereo Object templates, this is already configured, as the outputs are stereo. To configure this manually from a setup that uses mono outputs:
- Delete the mono outputs to be replaced by stereo outputs.
- Create a new Stereo output path in the I/O Output page by checking Create Default.
- Name the path with the Object numbers you want to convert for Stereo or Mono use.
- Verify or move the output assignments to the proper outputs.
When expanded in the bus page, the new path will reveal the subpaths that can be mapped to Objects.
In the Edit window Object column, the stereo Object assignment will be available from a stereo Audio track...
and the subpaths as mono Object assignments from a mono Audio track.
Object/Bus Toggle Automation
The Object/Bus Toggle setting can be automated on Object tracks. To facilitate writing Object/Bus Toggle automation for Object tracks, this parameter must be enabled in the Automation window (Window > Automation). To prevent Object/Bus Toggle automation from being written, or to protect existing Object/Bus Toggle automation from being overwritten, you can disable this parameter in the Automation window.
The Object/Bus Toggle button enabled (red) in the Automation window
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