Topics covered in this article:
- Creative use of Dolby Atmos
- Creative use of music in a Dolby Atmos post mix
- Creative practices for mixing music in Dolby Atmos
- Tips for mixing in Dolby Atmos
- Mastering, exports, and conversion
Creative use of Dolby Atmos
Sonic details off-screen add to the world surrounding a character and help the audience hear what the character is hearing.
Track where a character’s eyes are focused off-screen with sound — a monster in the room above or something in a tree above.
Use a change of room reverberation that includes height reflections to emphasize a character’s perception of an interior space they are entering.
A tall reverb can add to the perceived scale of a tall interior.
Recorded crowd audio can be panned around and above the listener to increase the sense of inclusion when reproducing a concert or comedy special.
Sound effects meant to give a sense of awe may be included in the overheads to enhance the perceived scale and scope of the scene.
- To fully envelop the listener, layers of sound can be split into multiple Objects and individually panned. Ocean sounds, for instance, can be lifted up over the listener and crash all around to give the feeling of being overwhelmed by the power of water.
Creative Use of Music in a Dolby Atmos Post Mix
Pull music back in the room to separate it from on-screen elements and add emotional impact to the scene. Give breathing room to SFX and ambiences placed in Left and Right by pulling the music into the Left-wide and Right-wide areas.
Music panning in the surrounds and overheads can create feelings of intimacy and inclusion. Music soaring into the overheads enhances an epic scene.
- Use Dolby Atmos-mixed music to maintain sonic continuity. When building a mix that contains a lot of dialog and music segments with SFX-heavy sections, using immersive mixing techniques on the music tracks can help maintain the feeling of immersion throughout your show.
Creative Practices for Mixing Music in Dolby Atmos
Percussion elements work particularly well in the front wide and front overheads.
Try to receive the drums stem broken down into smaller groups rather than one stereo or 5.1 drum stem.
Steady rhythmic elements, such as shakers, are meant to be locked in time and are best kept in the front half of the mix soundstage to assure cohesion with similar elements in L/R. This will help maintain tight rhythmic phase with the front rhythmic elements.
Look at using upmixers on stems or finished sub-mixes to create overhead space. These can turn stereo, 5.1, or 7.1 mixes and stems into 7.1.2 Beds. Some are built with algorithms that can retain centered vocals and downmixes in a stereo deliverable. Use the channel balance to control how much overhead sound is extracted.
The Size parameter can spread tracks to fill out larger areas of the sound stage and make the room sound bigger.
- There are a number of excellent 7.1.2 (and higher) reverbs on the market. Use the FMP feature (Follow Main Pan) in Pro Tools when sending an Object to a surround reverb to maintain natural panning in the reverb return.
Tips for Mixing in Dolby Atmos
Beds vs. Objects:
Typical uses for a 7.1.2 bed are diffuse sounds that don’t rely on precision placement:
- Reverb returns
- Musical elements meant to envelop the listener
Typical uses for Objects are sounds that require more precise and dynamic placement:
- Diegetic sound effects
- Individual music elements
There is no right or wrong approach, and the Bus/Object toggle can be utilized as needed.
Approach a mix from the top down – Dolby Atmos (7.1.2) to 5.1 to stereo. Approaching Dolby Atmos as “do 5.1 or 7.1 first and think of supplemental elements” does not lead to optimal results.
Building contrasting elements in the overheads and sides can increase the feeling of immersion.
Sounds that are intentionally diffuse in the overheads, like wind, are best placed in the overhead Bed channels, which cover the whole ceiling. Using Objects, especially without size metadata, may be too point-source to be as effective.
In the Dolby Atmos Panner, use the wedge shape automatic height panning mode when mostly staying left/right; use sphere for pans that go over and across the room.
Pay close attention to how many speakers are being used as you pan to the interior. Panning too far into the middle of the room can decrease the stereo image and quickly become mono.
Size can be a handy way to grow a sound to fill more speakers (with no phase issues), but as it is basically a 3D cube, it can quickly become room-filling mono. Small quantities of size can do a lot.
Humans have more acuity to localize things as being above us if they are higher in the frequency spectrum. If you want a stem to be accentuated in the overheads, it’s best to use tracks that have some frequency content above 2K.
Dolby Atmos allows for the full frequency range in all speakers, in both the cinema and at home. This is unlike prior practices for cinema, where surround arrays were bandlimited, removing any low-end content. In Dolby Atmos, don’t be afraid to move sounds with significant low-end away from the screen, as on-screen and off-screen Objects will have the same weight. However, it is important to be aware of where bass-heavy Objects are panned. Not only do humans perceive the verticality of higher frequencies better than bass frequencies, but most soundbars route much of the bass to the sub, so directionality will be perhaps be less noticeable than intended. Excessive low-end in a Dolby Atmos mix may take up too much headroom and weight in the stereo re-render if this is a target deliverable. (This doesn't pertain to the LFE channel, as LFE is not included in LtRt or LoRo re-renders. As such, it is not recommended to route content solely to the LFE channel.)
Pay attention to the Dolby Atmos soundstage between cuts. Abrupt changes between mixes in stereo and Dolby Atmos can be disorienting.
When panning in a mix stage that has deployed speaker arrays, remember that Objects move through individual speakers in an array, whereas Bed channels will address the arrayed speakers as a set.
Monitor a mix with Spatial Coding Emulation turned on. You can simulate the final presentation in Dolby Digital Plus at data rates used by leading streaming services by selecting 16 elements in Preferences or Settings.
In Pro Tools, VCAs can be used to control and hit loudness target levels as measured by the Renderer or plug-ins (via the loudness re-render).
In Pro Tools, you can use groups to gang only plug-in parameters in a given slot. Use this to your advantage to control compressors, limiters, filters, and EQ on multiple Objects.
Use care when using track groups and master busses with Objects, especially if you are toggling between Objects and Beds, as your Bed master busses may have additional processing, such as limiters.
Use the Groups in the Renderer to their full advantage; plan routing to make re-renders and multiple deliverables much easier.
- Use the Description field of the Renderer input page. This description shows up in Pro Tools in the "mapping to Object" field in the bus routing. This helps organize complex routing between the two applications.
Mastering, Exports, and Conversion
Use the LKFS metering in the Renderer to comply with loudness requirements. The meter conforms to international loudness measurement standards.
Alternatively, use the loudness-specific re-render with other loudness measurement plug-ins and applications.
Use the different monitoring paths in the Dolby Atmos Renderer to check different channel-based renders.
When recording your master, it may be helpful to add 2 pops to the top of the program if live re-renders are to be recorded. This will make it easier to sync stems for channel-based work downstream. Use FFOA to mark a First Frame of Action that will be read by the encoder.
If the Master File contains a 2-pop, use the “set manually” option of ADM or IMF IAB.mxf exports to remove the pop when exporting masters.
- Alternatively, if you want to remove the pops from Master Files destructively, use the Dolby Atmos Conversion Tool trim feature. You can also pre- and post-append the silence to the master if needed.