Topics covered in this article:
- Binaural audio renderer
- Binaural metadata
- Binaural render mode window
- Input/Master switch
- Input/Master status notification
- Setting distance settings
- 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 multi-channel 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 Dolby Atmos headphone experience. These settings are intended to give varying levels of spatialization to each of 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 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 Dolby Atmos 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 match to onscreen action or timbre. For Dolby Atmos post production the distance applied usually correlates to the environment portrayed onscreen i.e. interior/exterior, long shot/close up, etc. In Dolby Atmos Music Production 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 wil vary from mix to mix.
If a mixer wants to make an Object sound very close to the listerner’s 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 headphones, it is 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 unlock .atmos master file. 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. 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.
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).
Binaural Render Mode Window Input/Master Switch
Version 3.7 of the Dolby Atmos Renderer introduces the Input/Master switch, which decouples the Binaural Render Mode distance settings of the “Input” from that of an open Master file.
With the Input/Master switch toggled to Input, it is now possible to adjust the Binaural Render Mode distance settings as needed, independent of tes settings in an open Master file. It is also possible to copy the Binaural Render Mode distance settings from a Master file to the “Input” to enable punch-ins, or for use when creating a new Master. Conversely, Binaural Render Mode settings can be copied from the “Input” to an unlocked .atmos Master file.
Binaural Render Mode Status Notification
If the Binaural Render Mode distance settings do not match between the input and an open Master file, an orange indicator will be visible in the bottom left of the Renderer main window.
This indicator will turn off when the “Input” and “Master” match, indicating that punch-ins to the open Master are permitted.
Setting and Modifying the Binaural Render Mode Distance Settings
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 making changes to an open .atmos Master file, 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 a DAW rather than the Binaural Render Mode window in the Renderer application or Renderer Remote. Importantly, it also provides a way to save both the Input Configuration and the Binaural Render Mode distance settings as plug-in presets.
To use the Dolby Atmos Binaural Setting plug-in, insert the plug-in on any Audio track, or in Audio Suite if using Pro Tools.
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 connection status indicator will be green. The connection can also be seen in the Renderer preferences or settings Remote Clients tab.
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.
Any undefined inputs will appear with a yellow boundary to alert the user that these inputs need to be set or the input configuration copied from an open Master file.
The user interface shows a combined view of the Input Configuration and Binaural Render Mode windows. 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.
The plug-in also indicates when unused inputs are incorrectly assigned to objects. If an unassigned input in an open Master file (or a newly created Master file) is incorrectly assigned to an object, there will be a yellow border around that object in the plug-in window.
This mismatch will result in an error that will prevent both recording to a new Master file and punch-ins of an unlocked Master file. The mismatch can be resolved by clicking the illuminated Copy settings from master button (for an open Master file) or by manually assigning the unused inputs to null (---).
When the plug-in is used to control settings, a dialog appears in either the Input Configuration window Binaural Render Mode window to alert the user that the function is being controlled remotely.
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.