Using Pro Tools Aux IO to simultaneously monitor Atmos and stereo

Nov 29, 2022
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Using-Pro-Tools-Aux-IO-to-simultaneously-monitor-Atmos-and-stereo

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BennettS, 11/23/2022 6:06 PM

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BennettS, 11/29/2022 10:25 PM

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With the release of Pro Tools 2022.9 and Aux I/O, Mac users can now add any core audio device as extra inputs/outputs to their I/O in Pro Tools.

When working with an existing stereo mix it can be advantageous to A/B between the existing stereo mix and the current Atmos mix.

This article will cover how to use Aux I/O with the Dolby Audio Bridge, HDX, and a MTRX to create a setup that allows for simultaneous playback of Atmos and stereo reference tracks within a single Pro Tools session. This allows users working on a single computer system the ability to A/B two sources simultaneously, something that is possible with an external RMW and had previously required solo sets within the session on a single machine.

While this article uses HDX and MTRX, the same basic principle and workflow can be used with other Core Audio devices (given that they have sufficient output capabilities) and monitor control solutions.

It should be noted that using Aux I/O introduces variable latency into the system and any workflow using Aux I/O should take this into account. While this article covers the basic setup, Aux I/O is created and maintained by Avid, so any issues with Aux I/O should be directed to Avid support.

Aux I/O is covered in detail in the Pro Tools 2022.9 release notes, on the AVID Knowledge Base. Avid has also created a quick tip video covering Aux I/O and the Dolby Audio Bridge. Aux I/O and this workflow are Mac only.

In the Dolby Atmos Renderer:

Navigate to preferences and select the Dolby Audio Bridge as the input device and HDX (or other Core Audio device) as your output device.

Navigate to the Room Setup window (command + M) Routing tab and verify the speaker outputs. These outputs will not change with this workflow, but the headphone output may need to be changed to avoid overlapping output channels.

In Pro Tools:

Navigate to the Playback Engine window and ensure that the Playback Engine is set to Dolby Audio Bridge and the Aux I/O check box is enabled.

Navigate to the I/O Setup window Output tab.

Click the Aux I/O button to open the Aux I/O setup window.

Select HDX In and Out to add HDX as additional I/O. Click OK.

HDX now shows up after the Dolby Audio Bridge in the I/O Setup window and is available to use as I/O within the session.

In DADman (or other monitor control software):

Select 2 dedicated outputs for the stereo mix (for this example HDX outputs 63-64 are used). As noted above, verify that these channels do not overlap with existing Renderer output channels (speakers, headphones, or re-renders). The number of outputs available is dependent on the Core Audio output device.

Select these inputs as sources for a new stereo output in the source monitor profile in DADMAN

In the image below, source RMU is sourced from outputs 1-16 of the Renderer, and source Stereo is sourced from outputs 63-64 of Pro Tools.

Note: Using Dolby Audio Bridge as the main playback engine and HDX as an Aux I/O device does not utilize onboard DSP of the HDX card.