Fiedler Audio Dolby Atmos Composer

Screen 1: The main view of Dolby Atmos Composer.

Now you can create Atmos mixes using any DAW! But that’s not all this app has to offer...

It probably won’t have escaped your attention that mixing music for Dolby Atmos has become a big deal. Despite the inescapable fact that few music consumers out in the real world are fortunate enough to have listening spaces equipped with, say, 7.1.4 playback systems, there’s a whole load of music being mixed for Atmos. There are several reasons for this. Firstly, the Atmos format is smart: an Atmos mix, which might have been created in a studio equipped with a full‑fat 9.1.6 monitoring system, can, on playback, fold itself down to suit whatever channel format it encounters. Secondly, when an Atmos mix is created, the option is present to render a binaural version for headphone playback — you may have noticed that one or two folk out there primarily consume their music on headphones! Furthermore, Apple Music’s Spatial binaural format is derived from Atmos encoded material, and both Tidal and Amazon offer Atmos binaural music streaming.

Back in the studio world, where Dolby Atmos mixes are created, the workflow has to date required an ‘extended channel width’ capable DAW and Dolby’s not‑inexpensive Dolby Atmos Renderer app. At the time of writing, the only DAW apps that officially support the extended channel widths that the Dolby Atmos Renderer expects are Pro Tools (Studio and Ultimate), Logic Pro, Reaper, Nuendo, Pyramix and DaVinci Resolve. (See the box for an explanation of what I mean by ‘extended channel width’.)

Fiedler Audio’s Dolby Atmos Composer completely upsets the trolley of fruit, because it enables DAW apps that only offer mono or stereo channel widths to join the Atmos party. But there’s much more to Dolby Atmos Composer than that, because along with widening the range of DAW options it offers an Atmos mix workflow and routing philosophy that, to my mind, is better suited to the needs of music mix engineers than the somewhat prescriptive and convoluted demands of Dolby Atmos Renderer. Fiedler’s Dolby Atmos Composer is also pretty affordable.

Dolby Atmos Composer is available from Fiedler Audio in two flavours; the fully featured version and a less expensive Essential version that omits a few of the more advanced features. This review is of the full version. The Fiedler Audio website has a full list of features not included in Essential, but I’ll mention in this review if any feature isn’t included in Essential. While I’m on the subject of software with two versions, closely associated with Dolby Atmos Composer is version 1.5 of Fiedler’s SpaceLab, a multi‑channel/immersive algorithmic reverb plug‑in that’s available in Interstellar and Ignition editions — this is primarily a review of Dolby Atmos Composer, but it’s worth knowing that SpaceLab is fully integrated with it.

Objects & Beds

Before I get on to how Fiedler Dolby Atmos Composer can handle multi‑channel widths in DAWs that can only do stereo, I need to introduce a further complication that Atmos brings to the multi‑channel table: objects. Dolby Atmos is an ‘object oriented’ audio format in that any mono source can be described in terms of its position in 3D space defined by some associated XYZ coordinate metadata. In Atmos‑speak, such an audio source is an ‘object’. Objects can be placed anywhere in the 3D soundfield using a 3D panner plug‑in and they can be dynamically moved around as a mix progresses with as much exuberance as you can imagine. You want that trumpet to circle around above the listener’s head in time to the music? You’ll want to make it an Atmos object.

It’s substantially the concept of objects, with their positional metadata, that enables Atmos mixes to ‘fold down’ to match the abilities of the playback system. The Atmos decoder looks at the metadata and uses clever algorithms to work out how much of that trumpet, for example, should be sent to each available speaker in order for it to appear to be located as close as possible to where the XYZ coordinates say it should be. The more speakers in an Atmos replay (or monitoring) system, the more accurate the subjective result will be. However, Atmos doesn’t simply employ objects, it also allows for audio ‘beds’ (Fiedler Audio use the term ‘composite’ rather than ‘bed’). Beds are the Atmos equivalent of what we used to know as ‘surround sound’ — in other words, audio that’s reproduced across multiple channels to surround the listener and create phantom images. There’s no XYZ positional metadata encoded into beds, so their reproduced location is simply a result of traditional panning (although the panning can also include a height element).

An Atmos mix can contain a mix of beds and objects or be entirely created from one or the other, and the first head‑scratching moments that I suspect occur for any mix engineer on entering the world of Dolby Atmos using Dolby’s own Dolby Atmos Renderer app will concern session routing and how to accommodate beds and objects. It certainly was for me — I have quite possibly never scratched my head quite so much. Where once the paradigm was almost exclusively that a DAW output, bus or bounce is stereo, with the Dolby Atmos Renderer that is no longer the case, because not only are output buses much wider (the default Atmos bed for mix purposes is 7.1.2), there are also mono object tracks to accommodate that make their way, completely independently of the main output, to the Renderer. This all means that mix session routing and workflow using Dolby’s Atmos Renderer has to be completely rethought. And it also means that any mix session that was originally configured for conventional stereo will probably have to be rebuilt from the ground up if it’s to be mixed for Atmos.

A New Way

With the arrival of Fiedler Dolby Atmos Composer there’s a new way of working, and it’s one that’s possible with a far wider variety of host DAWs. There are two elements to Dolby Atmos Composer. The Dolby Atmos Composer plug‑in itself and a second plug‑in called Dolby Atmos Beam. Dolby Atmos Composer is inserted on the main output of the session, where it effectively sits in between the DAW and the nominated hardware interface. The output bus on which the DAC is inserted can be anything from a stereo channel width right up to 9.1.6. For the session I created for this review, I went with a stereo output bus to make it obvious from the screens that Dolby Atmos Composer doesn’t need an extended‑channel‑width DAW! Speaking of which, Screen 1 and Screen 2 illustrate, respectively, the main pane of the Dolby Atmos Composer plug‑in itself and the Dolby Atmos Composer mix session I created in Pro Tools for the review.

I’ll describe Screen 2 first because doing so will explain the role of Dolby Atmos Beam, but first I’d like to give credit where it’s due: the mix session incorporates stems from a track by a friend of mine, Danny Mulhern, and you can find the original stereo version of the track on Spotify. It’s a piece that, to my ears, falls into an ambient contemporary classical genre that’s well suited to an ‘immersive’ treatment.

Screen 2: A stereo mix session created by the author for the review tests.

You’ll see in Screen 2 that I’ve bused each audio stem to an aux track and inserted a send in each one for the Dolby Atmos Beam (DlbyAtmsB) plug‑in. The role of Dolby Atmos Beam is to send the audio on the track directly to the Dolby Atmos Composer (DlbyAtmsC), bypassing completely the basic mix functions of the DAW. So the track’s fader, mute, pan, solo and automation will no longer function (unless the DAW in question offers post fader inserts). This is fundamentally how Dolby Atmos Composer is able to work with extended channel widths in DAWs that can’t see beyond stereo — the actual ‘mixing’ is done in Dolby Atmos Composer rather than in the DAW.

The action of Dolby Atmos Beam to bypass the mix function of the DAW is why I chose to bus each stem to its own aux track rather than insert Dolby Atmos Beam directly on the stem tracks. Doing this means, firstly, that conventional fader moves and automation can be used to to tweak the mix, and secondly, it provides a neat way of creating a session that can be relatively easily configured for both traditional stereo and Atmos mix duties. In principle, you simply take an existing stereo mix session, add a second master output for Dolby Atmos Composer, and add an aux bus on which Dolby Atmos Beam is inserted as a send for each track.

You’ll also see in Screen 2 that I set up a conventional reverb aux track (Stereo FX) that takes sends from all but the Horns and Vibes to create a reverb to be used in the Atmos bed. The reasons for leaving the Horns and Vibes out of the bed reverb send are, firstly, that I chose to assign those two stems as Atmos objects with their own reverb and, secondly, that I decided to use Fiedler SpaceLab reverb for them. SpaceLab routing works in a similar manner to Dolby Atmos Composer, with a Beam insert that sends audio directly to the reverb plug‑in. Dolby Atmos Composer automatically identifies the presence of SpaceLab and includes it in its list of sources. And if you’re wondering why the SpaceLab Beam tracks have an additional send (bus 17‑18, set to 0dB) to the SpaceLab aux track, it’s to ensure the correct plugin processing order.

And speaking of the Dolby Atmos Composer list of sources, Screen 1 illustrates the main pane of the plug‑in. On the left is the list of Atmos Beam and SpaceLab Beam sources, each with a variety of options to configure; in the middle is a display of Dolby Atmos channels; and on the right are the Atmos output settings. Looking at the left‑hand side of the pane first, the options include mute and solo (remember, they no longer work on the source tracks, although they can be automated by enabling plug‑in automation) and a button that enables selection of the Atmos bed channel layout or enables sources to be assigned Atmos object status.

In the middle of the plug‑in pane, the list of Atmos channels reveals that the first 10 are the bed channels, followed by up to 118 object channels. My mix session employs six object channels (11 to 16), the first two being the stereo Vibes, the second two the stereo Horns and the third two objects created by the SpaceLab reverb. I configured SpaceLab as stereo for the purposes of screenshot clarity but it can go all the way to a 32‑channel full sphere. Each of these stereo sources requires two object tracks because in the Atmos world, objects are always mono. However, this raises some mix questions, because treating linked stereo channels as independent mono sources can potentially result in some unpredictable effects — it might actually make sense either to select the ‘left channel only’ mono option provided in Atmos Beam and SpaceLab Beam, or to create mono aux sends in the mix session. It seems to me a slight shame that Atmos Beam and SpaceLab Beam create mono sources simply by deleting the right channel.

It’s perfectly feasible to create an Atmos mix without the luxury of, say, nine monitors and a subwoofer. It can be done with just headphones.

Moving to the right‑hand side of the plug‑in pane, the configuration options cover output device and monitoring setup, and Atmos/binaural render export and loudness measurement. It’s all very intuitive and easy to use, though having written that I should mention features that don’t appear in Essential. This doesn’t have the loudness measurement features and it’s unable to monitor or export to headphones (binaural) and speakers simultaneously. One thing that it is important to emphasise, however, is that it’s not only in terms of export that Dolby Atmos Composer can produce a binaural render of an Atmos mix. The monitor output can be binaural too. So it’s perfectly feasible to create an Atmos mix without the luxury of, say, nine monitors and a subwoofer. It can be done with just headphones. Headphone‑based Atmos mixing is of course also possible with the Dolby Atmos Renderer app, but Dolby Atmos Composer makes it decidedly more accessible.

Screen 3: Dolby Atmos Beam.

Where The Magic Happens

Moving swiftly on to Screen 3, it shows the Dolby Atmos Beam pane and, in many respects, it’s where the Atmos magic happens. The Beam plug‑in not only sends audio to Dolby Atmos Composer, it also provides the 3D panning features that are perhaps the core creative element of all immersive audio. The panning display in ‘full‑fat’ Dolby Atmos Beam can show a top, side or 3D illustration of the monitor positions and the listener, but in Essential only the 3D display is available.

The icons stacked vertically on the right provide options to constrain the panning axes. The audio sources are displayed in the panning display by the light‑blue sphere icons — there are two of them because, in the case shown, the source track is stereo. The source icons can be selected by clicking singularly or in multiples, and once selected they can be moved around using the mouse. Alternatively, the azimuth, elevation and distance knobs can be adjusted. The spread knob increases or decreases the apparent size of an object in the immersive soundfield and the volume knob does what it says on the tin. In theory, the Atmos Beam volume knob could be used to replace the lost functionality of the source track fader. All the Beam panning controls, and the volume knob, can be automated by enabling plug‑in automation and going back to the mix session to make the required adjustments in the automation lanes. Dolby Atmos Beam doesn’t offer the panning tempo‑sync options that are found in, for example, Dolby’s 3D panner, but snapping automation break points to tempo markers can potentially achieve similar results.

Screen 4: The main window of the (separately available but deeply integrated) SpaceLab reverb.

Before I wrap up, while this isn’t ostensibly a review of the SpaceLab reverb, users of Dolby Atmos Composer will no doubt be interested in it, so I thought it worth a quick discusion. Screen 4 shows the main SpaceLab pane, with a panning display that’s not dissimilar to that provided in Atmos Beam. The orange blobs define the positions of the reverb inputs and, since I had SpaceLab configured in stereo mode for clarity’s sake, there’s just two. Screen 5 shows the SpaceLab reverb pane and, along with all the configuration controls you’d expect of a high‑end reverb plug‑in, there’s a good selection of presets. The ones I tried displayed a natural and seductive smoothness combined with fine detail in the reverb tails, and the ability to spread such reverb fun around an immersive soundfield is genuinely inspiring.

Screen 5: SpaceLab offers all the controls you’d expect to find on a good algorithmic reverb.

Music To My Ears?

When I first began to experiment with mixing music for Dolby Atmos, about six months or so before conducting this review, I used Dolby’s own Dolby Atmos Renderer. I’d naïvely imagined that I’d simply open an existing stereo mix and then just ‘do’ an Atmos version, but Dolby Atmos Renderer is primarily a commercial movie sound tool rather than a music mixing one, and it really was not that easy. In fact, I found the hoops it required me to jump through somewhat discouraging, as I’d spend more time working out and trying to understand the session workflow and routing options than I did on the creative possibilities of the mix.

Fiedler’s Dolby Atmos Composer is significantly more friendly to work with in a music mix context, and had I started my immersive music adventures with this, I suspect my progress towards creating worthwhile (to my ears) Atmos music mixes would have been far quicker and rather less painful. This software doesn’t yet do everything that Dolby Atmos Renderer can do. I’ve mentioned that there’s no panning tempo sync but there’s also no monitor EQ or delay functionality, so the way I understand how these things work, despite the fact that Dolby Atmos Composer itself has Dolby’s blessing, an Atmos mix room based on it would at the time of writing be unable to achieve official Dolby Atmos certification — but that isn’t necessarily a major problem, since it’s possible to master mixes in a Dolby certified room, and I understand from Fiedler Audio that these features are in the pipeline. And for many prospective users, its compatibility with DAWs that can’t handle extended channel widths will be a clincher. In fact, this could be a genuine breakthrough moment for Atmos music.