Topics covered in this article:
- Binaural audio renderer
- Binaural metadata
- Binaural render mode window
- Dolby Atmos binaural settings plug-in
Binaural Audio Renderer
In addition to the Object Audio Renderer used for Speaker outputs and channel-based downmixes and re-renders, the Dolby Atmos Renderer includes a separate Binaural Renderer.
The Binaural Renderer is used for monitoring Binaural audio on headphones, creating Binaural re-renders, and for writing Binaural metadata to .atmos master files.
The Binaural Renderer reproduces the experience of a multichannel loudspeaker listening experience as closely as possible over headphones.
The Binaural Renderer renders all of the bed and object inputs to create a compelling immersive mix over headphones using head-related transfer function (HRTF) filters. The Binaural Renderer includes its own limiter, which is used for the headphone output and re-renders.
Binaural Render Mode Metadata
Binaural settings are unique to the Atmos headphone experience. These settings are intended to give varying levels of spatialization to each the objects or bed channels to which they are applied and approximate the virtual distance between an object or bed and the listener’s head.
There are four possible settings: near, mid, far and off, the last of which lets the mixer turn binaural processing on an object off completely. The “mid” setting is the default and simulates the approximate distance between the sound source and the listener if they were listening on loudspeakers 1.5 meters away. If mixing on headphones the mixer can add some depth to the mix by choosing to set objects to “near,” and bring them closer, or to “far,” and push them further away.
From a creative standpoint this allows specific sounds to be more intimate and allow more space in others and is applicable to both music production and audio post production.
It is good practice to distribute objects equally between near, mid and far, and ultimately the settings the mixer chooses may be dependent on an Object’s timbre. This includes placing rhythmic sounds like drums in near or mid mode to give them more impact, and putting things that might already have some reverb on them like guitars and synths in far mode. These are by no means rules, and can vary a lot from mix to mix.
If a mixer wants to make an object sound very close to the listeners head but wants to avoid bringing an object “off the wall” or into the room, which may make the object sound more diffuse on loudspeakers, using the “near” setting can be a great way to achieve that effect on headphones without having to make any sacrifices for loudspeaker playback. Because of this difference in rendering between loudspeakers and headphone, its generally preferable to pan objects near the edge of the Atmos cube.
Binaural Render Mode metadata is written to the entire master file and is editable from an existing .atmos master file that is unlocked for editing. Binaural Metadata is used during encoding to AC4 IMS (Immersive Stereo).
An input configuration that defines multiples Beds can be used; however, there can be only one binaural mode for each bed channel, as they are combined into a single bed upon export/encode. If you have multiple beds defined and change the setting on one of them, the setting will change on all of the other bed inputs. For example, if three beds are defined, changing the left channel on one of them to Near will change the left channel on the other two.
Some Dolby Atmos music delivery services require Binaural Render Mode metadata not to be left at default values. Please refer to the relevant technical delivery specifications.
Binaural Render Mode Window
Binaural metadata settings are made in the Binaural Render Mode window.
- From the menu bar, select Window > Binaural Render Mode or press Command+B (Mac) or Ctrl+B (Windows).
The Binaural Render Mode window uses the input configurations defined in the Input Configuration window, or the input configuration from an open master file.
A visual indicator and switch will be present if a Master File is loaded.
To make changes in the distance model settings, click on any input in the setting column to highlight and reveal the setting drop-down menu. If a .atmos master file is open it must be unlocked for editing.
In addition to the descriptive tags (Off, Near, Mid, Far), different icons are used to indicate object distance setting.
To change multiple inputs at the same time:
- Shift-click on inputs to select contiguous inputs.
- Command/Ctrl-click on inputs to make non-contiguous selections.
After selecting multiple inputs, their settings can be changed at the same time.
Controls can be adjusted while live monitoring or while playing back a master. Headphone processing (or Headphone Only mode) must be enabled, and the Headphone Render mode must be set to Binaural in Preferences or Settings.
Binaural render mode settings can be displayed in the main Renderer Window Object view from the View/Show drop-down menu.
Dolby Atmos Binaural Settings Plug-in
The Dolby Atmos Binaural Settings plug-in provides a way to set and modify the binaural render settings from Pro Tools rather than the Binaural Render Mode window in the Renderer application or Renderer Remote.
To use the Dolby Atmos Binaural Setting plug-in, instantiate the plug-in on any Audio track, or in AudioSuite.
The plug-in needs to establish communication with the Dolby Atmos Renderer independently of the DAW. This is done by entering the IP address or hostname of the external Renderer or entering localhost if the Renderer is running internally.
Once communication with the Renderer is established, the plug-in will populate with the input configuration from the Renderer and any existing settings from the Binaural Render Mode window. The user interface is almost identical, but an optional grid view provides a way to see all 128 inputs and the distance model settings at a glance and make changes as needed.
When the plug-in is used to control settings, a dialog appears in Binaural Render Mode window to alert the user.
Note that these settings are not automatable and apply per channel for the duration of the master. Care should be taken in editing these after mixing has begun, as changes to these settings are not undoable.
This is also indicated in the main Renderer window status bar.
When a master file is loaded and opened for editing, the Binaural Renderer Mode Configuration is set from the master. If the Binaural Render Mode settings match that of the master file while the plug-in is connected, this will be indicated by a blue dot. If the plug-in Binaural Render Mode setting is changed, the dot will indicate that they no longer match and turn orange. Accepting the changes by clicking Copy Setting from Input to Master will return the status dot to blue, indicating that the plug-in matches the Renderer Binaural Mode window.
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