by Florian Grond, PhD

In this blog entry, I will first give a brief overview of HOA, followed by an explanation of some relevant features of Dolby Atmos. Then, I will describe the general workflow connecting both approaches to create immersive audio experiences. I will conclude with some comments regarding the possibilities and limitations of some specific DAWs for the proposed workflow. 

Higher-order Ambisonics (HOA) plays a key role in all situations that require isotropic sound scenes, i.e. scenes that uniformly cover each direction. These scenes comprise VR, AR, XR, video games and generally speaking 360° audiovisual content, for instance when streaming over YouTube or Facebook. The key advantage of HOA is the ability to transform and conveniently manipulate the sound scene in a uniform and mathematically rigorous way. Ambisonics started in the 70ies through Michael Gerzon’s work with what today is referred to as first-order Ambisonics (FOA) [1]. Higher-order Ambisonics was developed in the 90ies by various researchers [2]; the spatial resolution and the sense of depth in the sound scene improved significantly. Without explaining Ambisonics in detail here I will cover some aspects that are relevant to the workflow; if you want to know more, I have compiled more about HOA below [3].       

The A- and the B-format
 
It is important to know that the raw output of an Ambisonics microphone array, the A-format, needs to be converted into what is known as the B-format before using it in an Ambisonics production workflow.  This is sometimes a bit of an obstacle for the novice. Unlike in a channel-based approach, the audio channels of the B-format are not associated in a direct way with spatial directions or positions, like the positions of speakers in the playback system, for instance. However, the more abstract representation of the sound scene in the B-format makes sound field operations like rotations fairly straightforward. 

​Although multichannel audio is at its base, the B-format is only an intermediary step and requires decoding before you can listen to a meaningful output. This decoding process can either yield speaker feeds ranging from classic stereo to multichannel surround sound setups for a conventional channel-based output, or it can result in a binaural experience over headphones. This is just one of the reasons why one would like to deliver immersive audio recorded through Ambisonics over playback solutions that support Dolby Atmos. For delivering a mobile and immersive listener experience with comparably small hardware requirements, the capabilities of headphones with integrated head-tracking are particularly attractive.

Ambisonic orders
 
For FOA recordings, the A- and the B-format have both 4 channels. The spatial resolution is limited, and sound sources usually appear as if they are all at the same remote distance. For full-sphere HOA solutions the A-format has typically more channels than the B-format. As an example, the ZYLIA ZM-1 has 19 channels as raw A-format output and 16 channels after converting it to 3rd order Ambisonics. It is important to remember these channel counts when planning your workflow with respect to the capacities of the DAW in question. 

Dolby Atmos is a surround sound technology developed by Dolby Laboratories. On the level of channel counts and positions, it expands on existing surround sound systems by adding height channels. While Dolby Atmos as a format is agnostic with respect to the speaker layout of the playback system, the inner workings are in part inspired by a channel-based approach. Dolby Atmos is not isotropic as Ambisonics is, however, it does aim in a similar way to envelop the listener from many directions, hence the desire to explore links with the immersive quality of HOA recordings.
 
In order to represent rich 360° audio content, Dolby Atmos can handle internally up to 128 channels of audio. The Audio Definition Model (ADM) ensures a proper representation of all the metadata related to these channels. Dolby Atmos files are distributed through the Broadcast Wave Format (BWF) [4]. From a mixing point of view, and also for combining it with Ambisonics, it is important to be aware of two main concepts in Dolby Atmos: beds and audio objects.  

Beds
 
You can think of beds in two ways:
 

1. Beds are a channel-based-inspired representation of audio content following surround sound speaker layouts plus additional up to 4 height channels.
2. In terms of audio content that you would send to beds, this can be for instance music that you mix for a specific surround setting. You can also think of it in general terms as soundscapes that provide a background or atmosphere for other audio elements. This background sound is spatially resolved. 

 
If you think for instance of a nature soundscape, this could be trees with rustling leaves and a creek with running water, all sound sources with more or less distinct positions. Take an urban soundscape as another example and think of traffic with various moving cars, these are sound sources that change their positions, but you would want to use the scene as is and not touch the sources individually in your mix. These are all examples of immersive audio content that you would send to beds. 

Audio objects
 
Dolby Atmos also allows for sounds to be interpreted as objects with positions in three dimensions. In a mix, these are objects that allow for control of their position in x, y, and z independently of the position of designated speaker channels. See below [5], for reading up more on beds and objects.

There are many ways how HOA sound material can be used in Dolby Atmos, involving both, beds and objects and the mixer is free to select or switch between those possibilities. For the scope of this article, let’s focus on mapping HOA to beds, in order to make a first step towards leveraging the immersive properties of Ambisonics with the end user format of Dolby Atmos. 

Mapping HOA to beds
 
While beds are channel-based in their conception, they may be rendered differently, depending on the speaker count and layout of your system. Think of beds as your main mix bus and let’s think of input for beds as surround configurations (2.0, 3.0, 5.0, 5.1, 7.0, 7.1, 7.0.2, or 7.1.2). In order to take advantage of the high resolution of 3rd order recordings made with the ZYLIA ZM-1, we will pick the 7.0.2 configuration with 7 horizontal and two elevated frontal speakers and we will decode the Ambisonic B-format to a virtual 7.0.2 speaker configuration. This results in a proper input for a Dolby Atmos bed.

The signal chain
 
Starting with a raw recording made with the ZYLIA ZM-1 we will then have the following signal chain:

STEP 1
Step one is the raw output of the microphone array, the A-format. For the ZYLIA ZM-1 this is an audio file with 19 channels. From a post-production and mixing perspective, all that matters here is where you placed your microphone with respect to the sound sources. If you want your work environment to include this step of the signal chain, the tracks of your DAW need to be able to accommodate 19 channels. But this is not absolutely necessary, you can start with step 2.

STEP 2
The 3rd order Ambisonic B-format contains 16 channels. For the conversion from step one to step two, you can use the Ambisonic Converter plugin from Zylia [6]. If your DAW cannot accommodate the necessary 19 channels for step one you can also convert offline with the ZYLIA Ambisonics Converter application, which also offers you batch conversion for multiple assets [7]. In many situations, it is advisable to start the signal chain with step 2, in order to save the CPU resources used by the A to B conversion for other effects. From a mixing perspective, operations that you apply here are mostly rotations, and global filtering, limiting or compression of the immersive sound scene that you want to send to Atmos beds. You will apply these operations based on how the immersive bed interacts with the objects that you may want to add to your scene later. There are various recognized free tools available to manipulate HOA B-format, for instance, the IEM [8] or SPARTA [9] plugin suites.

STEP 3
Then, The Ambisonic B-Format needs to be decoded to a virtual surround speaker configuration. For this conversion from the B-format, you can use various decoders that are again available from multiple plugin suites like IEM and SPARTA. ZYLIA Studio Pro [10] allows you to decode to a virtual surround layout directly from step one, the raw A-format recordings, which means that you can bypass step 2. For some background audio content, this maybe a perfectly suitable choice. Part of the roadmap for ZYLIA Studio Pro is to also offer A-format input, making it a versatile high-quality decoder. From a mixing perspective and depending on the content of your bed input, you may want to choose different virtual surround configurations to decode to. Some content might be good on a smaller, more frontal bed e.g. 3.1, and other content will need to be more enveloping. If your DAW has a channel count per track that is limited to surround sound setups, you will need to premix these beds as stems. 

STEP 4
​This bed then needs to be routed to Dolby Atmos. The details are beyond the scope of this article, and there are many excellent tutorials available that describe this process in detail. Here I want to mention that some DAWs have Dolby Atmos renderers built in, and you can study everything you practically need to know within these DAWs. With other DAWs, you will need to use the external Dolby Bridge [11]. This has a steeper learning curve to it but there are also many excellent tutorials out there that cover these topics [12]. There are also hardware solutions for Dolby Atmos renderings which interface with your speaker setup, but we will not cover them here. In Dolby Atmos, you will likely also integrate additional sources as objects, and you will control their 3D pan position with the Dolby Atmos Music Panner plug-in in your DAW. From a mixing perspective: the sonic interaction between the bed and the objects will probably make you revisit steps 2 and step 3 in order to rebalance, compress or limit your bed to optimise your mix.  

STEP 5
​You will need to monitor your mix to make sure that the end user experience is perfect. Only very few of us will have access to a Dolby Atmos studio for their work. For bedroom studio owners, you can listen to your mix always over headphones as a binaural rendering, on some recent OSX platforms over the inbuilt Atmos speakers, and with AirPods even over headphones with built-in headtracking. These solutions might be options depending on what you are producing for. Regarding this highly debated question, on whether you can mix and master over headphones, I found the following article very insightful [13], elaborating on all pros and cons and also pointing out that the overwhelming majority of end users will listen to music over headphones. With regards to an Ambisonic mix, using headphones means that the listener will be always in the sweet spot of the spatial reproduction.        

I will finish by discussing the steps of the signal chain on a couple of selected DAWs focusing on Ambisonics and beds only. In general, when planning your HOA to Dolby Atmos workflow, you need to understand how Dolby Atmos is supported in the DAW of your choice [14]. Either a Dolby Atmos renderer is integrated, or you need to get acquainted with the Dolby Bridge. On the side of HOA, you need to understand how many channels per track your DAW supports, and whether you can start working with the A-format, the B-format or premixed beds as stems.  

REAPER
Reaper is amongst the first choices when it comes to higher-order Ambisonics, due to its 64-channel count per track. Hence for the HOA aspect of the workflow sketched above, there are no limitations. However, you will need to familiarize yourself with the Dolby Bridge and the Dolby Atmos Music Panner plug-in.  

PRO TOOLS
In regular Pro Tools, you will also use the Dolby Atmos Music Panner plug-in and the Dolby Bridge. Since Pro Tools has a limitation of 16 channels per track, you will need to convert all your Ambisonic assets to B-format before you can start mixing. Upgrading to Pro Tools Studio or Flex [15] adds Dolby Atmos ADM BWF import/export, native immersive panning, I/O set-up integration with the Dolby Atmos Renderer, and a number of other Dolby Atmos workflow features as well as Ambisonics tracks.

LOGIC
In the most recent versions of Logic, Dolby Atmos is completely integrated, so no need to use the Dolby Bridge. For the monitoring of your mix, Logic will play nicely with all Atmos-ready features from Apple hardware. However, the channel count per track is limited to beds with 7.1.4. In theory, this means that you would have to premix all the beds as multichannel stems. While you can import ADM BWF files, as the Dolby Atmos project is ready for mixing, it is less obvious how to import a bed input as discussed above. In any case, once you have a premixed bed, the only modifications available to you in the mixing process are multi-mono plugins (e.g., filters), so you cannot rotate the Ambisonic sound field anymore at this point. To summarize for Logic, while Dolby Atmos is very well integrated, the HOA part of the signal chain is more difficult to realize.   

NUENDO
Nuendo also has Dolby Atmos integrated and it also features dedicated Ambisonic tracks up to 3rd order which can be decoded to surround tracks. This means you have a complete environment for the steps of the workflow described above. 

DAVINCI RESOLVE
While being mostly known as a video editing environment, DaVinci Resolve features a native Dolby Atmos renderer that can import and export master files. This allows for a self-contained Dolby Atmos workflow in Resolve without the need for the Dolby Atmos Production or Mastering Suite. DaVinci Resolve also has the Dolby Atmos renderer integrated and the tracks can host multichannel audio assets and effects. 

I hope this gives a general overview of how to connect HOA with Dolby Atmos. The proposed workflow is making use of beds in an orthodox way, but this is not the only way how HOA recordings can be mapped to Dolby Atmos. The 128 channels of Dolby Atmos including the object channels offer plenty of opportunities to explore.
 
If you like this article, then please let us know in the comments what we should describe in more detail in future articles?

[1] The publication by Michael Gerzon introducing FOA:

• M. Gerzon, "Periphony: With Height Sound Reproduction," J. Audio Eng. Soc., vol. 21, no. 1, pp. 2-10, (1973 February.)

[2] References for early works on HOA:

• J. Daniel, J. Rault, and J. Polack, "Ambisonics Encoding of Other Audio Formats for Multiple Listening Conditions," Paper 4795, (1998 September).
• R. Nicol, and M. Emerit, "3D-Sound Reproduction Over an Extensive Listening Area: A Hybrid Method Derived from Holophony and Ambisonic," Paper 16-039, (1999 March).
• An article by Jérôme Daniel about the HOA from the Ambisonics symposium 2009: LINK​

[3] A great source for HOA:     

• F. Zotter, M. Frank, "Ambisonics: A practical 3D audio theory for recording, studio production, sound reinforcement, and virtual reality", Springer Nature; 2019: LINK

[4] You can get access to Dolby’s Audio Definition model (ADM) specification here: LINK

• Here, you find more information about the broadcast Wave format BWF: LINK

[5] More information about the difference between beds and objects: LINK
[6] The Zylia Ambisonics Converter plugin: LINK
[7] The Zylia Ambisonics Converter: LINK
[8] The IEM plugin suite: LINK
[9] The SPARTA plugin suite: LINK
[10] Zylia Studio Pro plugin: LINK
[11] A video tutorial for using the Dolby Bridge with Pro Tools: LINK
[12] A video tutorial for using the Dolby Bridge with Reaper: LINK
[13] An blog post about the limits and possibilities of mixing Dolby Atmos via headphones by Edgar Rothermich: LINK
[14] Information about Dolby support for various DAWs: LINK
[15] Here you can compare Protools versions and their Dolby and HOA support: LINK

In 0ctober 2021, Mark Zuckerberg announced Metaverse – a digital future of people’s social interaction. A space where representations of people – avatars – work and entertain together in the virtual world. It sounded stunning, but also it raised multiple questions: how to do it? How make this vision come true? What are the tools that can help content creators to compete fairly in this new Metaverse market?
 
Since then, various organizations and private companies have been mobilizing their R&D teams to find technologies that could connect virtual reality, social media, and teleconference systems. Metaverse Standard Forum indicates the vast potential of what we can develop together.
 
Zylia started to work on tools for making volumetric audio many years before people even heard about Metaverse. We wanted to be ready once they are most needed – this time has come!
 
Follow the activities of Metaverse Standard Forum to stay on top of the technologies that will drive Metaverse in the next few years.
 
#metaverse #virtualreality #gamedevelopment #opportunities #zylia #Volumetric #6dofAudio #3Daudio #immersive

Last year, our creative sound engineer Florian Grond had the privilege to accompany Christophe Papadimitriou during the production of QUATRE, an immersive work of audio art connecting soundscapes with music and improvisation. The music was recorded with ZYLIA’s 6DoF VR/AR set in the studios of the Orford Music centre in Quebec, Canada and the nature soundscapes were recorded with a single ZYLIA ZM-1 microphone outdoors, the whole composition was mixed and mastered as a binaural album. Christophe was so kind to grant us an interview and to speak about what moves him as an artist and what inspired him to embark on this immersive audio journey.
 
L'année dernière, notre ingénieur du son créatif Florian Grond a eu le privilège d'accompagner Christophe Papadimitriou lors de la production de QUATRE, une œuvre d'art audio immersive reliant les paysages sonores à la musique et à l'improvisation. La musique a été enregistrée avec l'ensemble 6DoF de ZYLIA dans les studios du centre musique Orford au Québec, Canada, et les paysages sonores de la nature ont été enregistrés avec un seul ZYLIA ZM-1 microphone en extérieur, l'ensemble de la composition a été mixé et masterisé comme un album binaural. Christophe a eu la gentillesse de nous donner une interview et de parler de ce qui le touche en tant qu'artiste et de ce qui l'a inspiré à se lancer dans ce projet audio immersive.

Christophe Papadimitriou: I arrived in Quebec from France in 1978. I live in Montreal and I have performed as a musician ever since I graduated from Concordia University in 1992. There, I studied double bass with the great jazz musician Don Habib and classical music with Éric Lagacé. Since then, I have shared the stage with many artists from Montreal, especially from the jazz and world music scene as well as with chanson artists.
For the past 10 years, I have been lucky enough to be able to play and record my own compositions for theatre projects as well as for jazz and world music productions, which is what I like most! I love composing and sharing with the public the fruit of my creativity and my imagination.

Je suis arrivé au Québec de France en 1978 et je vis à Montréal où je travaille comme musicien depuis ma sortie de l’Université Concordia en 1992. J’y ai étudié la contrebasse avec les grands professeurs et artistes jazz et classiques Don Habib et Éric Lagacé. Depuis, j’ai partagé la scène avec de nombreux artistes montréalais, surtout en jazz, musique du monde et chanson.
Depuis les derniers 10 ans, j’ai la chance de pouvoir jouer et enregistrer mes propres compositions au sein de projets autant en théâtre, jazz et musique du monde.
C’est ce qui me plait le plus, j'adore composer et partager avec le public le fruit de ma créativité et de mon imagination. 

Christophe Papadimitriou: For me, music is the most faithful way to express emotions and inner feelings. Transcending words and images, music allows musicians and audiences to connect and to share simultaneously both collective and individual experiences. When the magic works and the musicians and the audience are transported by this positive energy, then we can experience a moment of grace… These moments are rare and for that, very precious.
 
Pour moi, la musique est le moyen d’exprimer le plus fidèlement les émotions et l'intériorité. Transcendant les mots et les images, la musique permet aux musiciens et à l’auditoire de se connecter ensemble et de vivre simultanément une expérience à la fois collective et individuelle. Quand la magie opère et que musiciens et audience sont transportés par cette énergie positive, alors nous pouvons vivre un moment de grâce…Ces moments sont rares et pour ça, très précieux.

Christophe Papadimitriou: ​The Covid pandemic had a significant impact on many levels on our society and forces us to reconsider, if this was not already the case, the connection we have between us and with the planet. Questioning human activity and our impact on nature became an absolute priority for me. In general, this realization has an impact on the arts and it became clear to me that this would be the material for my next project. This is how the idea came about to create a work based on the cycle of the seasons with the desire to reconnect with the nature that surrounds us. With this work, I want to create a dialogue between music and the sounds of nature, a moment of personal and quasi-meditative respite where the listener is invited to encounter nature in a different way and to recreate a link with what is precious.
 
La pandémie de Covid a eu un impact important sur plusieurs plans de notre société et nous oblige à prendre conscience, si ce n’était pas déjà le cas, de notre interconnexion au niveau planétaire. Une remise en question de l’activité humaine et de notre impact sur la nature sont des enjeux absolument prioritaires. Cette prise de conscience a naturellement un impact sur l’art en général et pour moi, il est devenu évident que ce serait la matière mon prochain projet. C’est ainsi qu’est née l’idée de créer une œuvre basée sur le cycle des saisons avec la volonté de reconnecter avec la nature qui nous entoure. Je voulais par cette œuvre créer l’effet d’un dialogue entre musique et sons de la nature, un moment de répit personnel et quasi-méditatif où l’auditeur est invité à rencontrer autrement la nature et à recréer du lien avec le précieux.

Zylia: Who are the other musicians in QUATRE?
Qui sont les autres musiciens de QUATRE ?

Christophe Papadimitriou: ​Key contributors to the project are Luzio Altobelli (accordion and marimba), Omar Abou Afach (viola, oud and nai) and Florian Grond (sound design). In addition to the great mastery of their instruments, Luzio and Omar bring their sensitivity and humanity to each piece of the work. It was very interesting to observe during the production of Quatre (which took place over more than a year), how the group dynamic evolved over the seasons. Our cultural differences and also the points that bring us together. All this is reflected in the recorded music. We can hear moments of great unity and also solos where the instrumentalists can let themselves go to follow their own vision, to express their feeling of the moment. Quatre is a work with written pieces but it also leaves plenty of room for improvisation. Thus, the musicians were able to express themselves in their own musical language which enriched the work with various traditional timbres (Middle East, Mediterranean and Quebec).
 
Collaborateurs essentiels au projet : Luzio Altobelli (accordéon et marimba), Omar Abou Afach (alto, oud et nai) et Florian Grond (design sonore). En plus de leur évidente maîtrise instrumentale, Luzio et Omar apportent leur sensibilité et leur humanité dans chaque pièce de l'œuvre. Il a été très intéressant de constater pendant la réalisation de Quatre (qui s'est déroulée sur plus d’un an), la dynamique de groupe qui évoluait au fil des saisons. Nos différences culturelles et aussi les points qui nous rassemblent. Tout ceci se perçoit dans la musique enregistrée. On peut entendre des moments d’une grande unité et aussi des solos ou l’instrumentiste peut se laisser aller à sa propre vision, son ressenti du moment. Quatre est une œuvre avec des pièces écrites mais qui laisse toujours une bonne place à l'improvisation. Ainsi, les musiciens ont pu s’exprimer dans leur propre langage et l’œuvre est riche de sonorités diverses (Moyen Orient, Méditerranée et Québec). 

Christophe Papadimitriou: During an improvised COVID concert outdoors on my terrace, Florian recorded us for the first time, starting with a single ZM-1, which was when I discovered immersive audio recording technology. A bird was singing along while we played, and I was immediately taken by the possibility of connecting my music with the sounds of nature and treating it like a 4th instrument. It is through this technology that we can really feel surrounded by the sound universe that we have created. Quatre is conceived as a journey, a walk, through Quebec's nature through the seasons. To support this feeling, we have integrated footstep sounds (in the snow, in the sand, in the water) in each season to help the listener to imagine herself walking in the forest or more generally in nature. The feedback we got from listeners show that the immersive effect was quite a success.
 
Pendant un concert Covid improvisé sur ma terrasse, Florian nous a enregistré pour la première fois, d’abord avec un seul ZM-1, c’était là que j’ai découvert la technologie d’enregistrement en audio immersif. Un oiseau chantait le long de notre jeu et j’ai été charmé par la possibilité de connecter ma musique avec les sons de la nature, et de traiter celle-ci comme un 4e instrument. C’est cette technologie qui nous a permis de réellement se sentir entouré par l’univers sonore ainsi créé. Quatre est conçue comme un voyage dans la nature québécoise au fil des saisons. D’ailleurs, nous avons intégré à chaque saison des sons de pas (dans la neige, dans le sable, dans l’eau) qui aident l’auditeur à se projeter en train de se promener en forêt ou plus général en nature. Les témoignages que nous avons reçus après l’écoute montrent que l’effet d’immersion est bien réussi.

Christophe Papadimitriou: I am convinced that listening through headphones offers the best conditions for total listener presence. The work has many subtleties and the dynamic range of the sound is great, going from very soft to loud, so headphones are necessary to appreciate every detail.
Today, a lot of people listen to music through headphones, but often while multitasking at the same time. To fully enjoy the music of Quatre, we suggest a moment of respite where the audience, comfortably seated, is completely dedicated to the act of listening. We are currently in the process of setting up several collective listening sessions with headphones in the Montreal area. These sessions will accommodate about fifteen listeners at a time and are created with the aim of discovering this work and providing an experience connecting art, nature and humans.
 
Nous sommes convaincus que l’écoute au casque offre les meilleures conditions pour une présence totale de l’auditeur. L'œuvre a beaucoup de subtilités et l'amplitude sonore est grande, passant de très doux à fort, le casque est nécessaire pour ne rien manquer.
Beaucoup de gens écoutent leur musique au casque de nos jours, mais souvent en faisant une autre tâche en même temps. Pour profiter de l’expérience au maximum, nous privilégions un moment de répit ou l’auditeur, confortablement installé, se dédie complètement à l’écoute. Nous sommes en train de mettre en place plusieurs séances d’écoute collectives au casque, dans la région de Montréal. Ces séances permettant une quinzaine d'auditeurs à la fois sont créées dans le but de faire découvrir cette œuvre et de faire vivre une expérience connectant art, nature et humains.

Support our approach and the artists by downloading Quatre here:
Appuyez notre démarche et supportez les artistes en téléchargeant Quatre ici :
 
https://christophepapadimitriou.bandcamp.com/album/quatre-sur-le-chemin

In July 2021, Jordan Rudess (Dream Theater) and his friends Steve Horelick and Jerry Marotta gathered at the Dreamland Recording Studios, NY, for a spectacular and singular concert event, spanning classical to impressionistic piano genres to progressive, experimental rock with spacious synth soundscapes. The team at Zylia captured the performance with multiple 360° cameras and 3rd order Ambisonics microphones, allowing the creation of a unique, immersive 3D journey.         
 
Zylia’s 3D Audio recording solution gives artists a unique opportunity to connect intimately with the audience. Thanks to the Oculus VR application, the viewer can experience each uniquely developed element of the performance at home as vividly as it would be by a live audience member. Using Oculus VR goggles and headphones, viewers have the opportunity to:

• watch the concert from several different perspectives each with a 360° view,   
• listen to the music in 360° spatial audio at every vantage point,
• tilt and turn their head and witness how 3D audio follows their movement perfectly
• hear the unique acoustics of the venue,
  
• feel the fantastic atmosphere of the event.

To create a multi-point 360° audio-video experience, we set up a recording spots on the stage amongst the musicians – each equipped with a ZYLIA ZM-1S and a 360° camera. This allows a listener to choose from which point they watch the concert and experience it in immersive 360°. With every move, the sound projected to the listener’s ears changes, corresponding to the position of their head. To combine 360° video with 360° audio, we used a video editor (Adobe Premiere), a Digital Audio Workstation supporting 19-channel tracks (Reaper) as well as Unity3D and Wwise engines.

Recording was done using ZYLIA 6DoF Recording Application. Qoocam 8K cameras were used for video recording.

A RAW signal from microphones was synchronized using ZYLIA 6DoF Recording Application and converted to 3rd order Ambisonics format. Output Ambisonics signals were mixed in DearVR software.

The 360° videos from the Qoocam 8K were stitched and converted to an equirectangular video format.

For the purpose of distributing the concert, a VR application was created in Unity3D and Wwise engines for Oculus Quest VR goggles.

Multi-point 360° audio and video – the outcome

The outcome of this project is an Oculus application with the concert “Jordan Rudess & Friends in 3D Audio” – an immersive, deep, and emotionally engaging music experience.

OBA
 
The most popular method of producing a soundtrack for games is known as Object-based audio. In this technique, the entire audio consists of individual sound assets with metadata describing their relationships and associations. Rendering these sound assets on the user's device means assembling these objects (sound + metadata) to create an overall user experience. The rendering of objects is flexible and responsive to the user, environmental, and platform-specific factors [ref.].​

​In practice, if an audio designer wants to create an ambient for an adventure in a jungle, he or she needs to use several individual sound objects, for example, the wind rustling through the trees, sounds of wild animals, the sound of a waterfall, the buzzing of mosquitoes, etc. The complexity associated with Object-based renderings increases with the number of sound objects. This means that the more individual objects there are (the more complex the audio scene is) the higher is the usage of the CPU (and hence power consumption) which can be problematic in the case of mobile devices or limitations of the bandwidth during data transmission.  

VSBA
 
A complementary approach for games is Volumetric Scene-based audio, especially if the goal is to achieve natural behavior of the sound (reflections, diffraction). VSBA is a set of 3D sound technologies based on Higher-Order Ambisonics (HOA), a format for the modeling of 3D audio fields defined on the surface of a sphere. It allows for accurate capturing, efficient delivery, and compelling reproduction of 3D sound fields on any device (headphones, loudspeakers, etc.). VSBA and HOA are deeply interrelated; therefore, these two terms are often used interchangeably. Higher-Order Ambisonics is an ideal format for productions that involve large numbers of audio sources, typically held in many stems. While transmitting all these sources plus meta-information may be prohibitive as OBA, the Volumetric Scene-based approach limits the number of PCM (Pulse-Code Modulation) channels transmitted to the end-user as compact HOA signals [ref.].

To summarizing, the advantages of the Volumetric Scene-based audio approach affecting the CPU and power consumption are:
 

• Rendering complexity independent of the number of objects in the scene, decreasing the CPU usage from 100 to 10 000 times in comparison to OBA

The source signals are converted to a fixed number of HOA signals, uniquely dependent on the HOA order, and not on the number of objects present in the scene (even if the audio scene is created from thousands of audio signals).

• Possibility of rendering HOA signals to any reproduction device

A single format of HOA signals (with the addition of a few audio objects, if needed) can be reproduced on any device including headphones, soundbars, mobile etc.

• Lower number of PCM channels sent to the end user

HOA signals can be “spatially compressed” while maintaining high levels of spatial accuracy.

• Personalized interaction with immersive audio

HOA can be reproduced through headphones via the HOA to Binaural rendering and paired to Head-mounted displays to allow real-time adaptation of the sound field to head rotations in VR productions. It also facilitates 360° video applications where the sound field rotation can typically be controlled by moving a finger on the touch screen of a mobile device.
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• Lower production costs for loudspeaker layout

The production (mixing and mastering) is performed in a single HOA format which can be rendered to any channel-based audio format for any loudspeaker layout (e.g., 2.0, 5.1, Dolby Atmos, …).  There is no need to produce separate mixes for each target loudspeaker layout which reduces production costs and efforts.

One of the most innovative and efficient tools for producing Volumetric Scene-based audio is ZYLIA 6 Degrees of Freedom Navigable Audio solution. It is based on several Higher Order Ambisonics microphones which capture large sound-scenes in high resolution, and a set of software for recording, synchronizing signals, converting audio to B-Format, and rendering HOA files. The Renderer can be also used independently from the 6DoF hardware – to create navigable 3D assets for audio game design.

ZYLIA 6 DoF HOA Renderer is a MAX/MSP plugin available for MAC OS and Windows. It allows processing and rendering ZYLIA Navigable 3D Audio content. With this plugin users can playback the synchronized Ambisonics files, change the listener’s position, and interpolate multiple Ambisonics spheres. The plugin is also available for Wwise, allowing developers to use ZYLIA Navigable Audio technology in various game engines.

Volumetric Scene-based audio and Higher Order Ambisonics can be used for many different purposes, not only for creating soundtracks for games. This format is very efficient when producing audio for:
 

• Virtual, Augmented, and Mixed Realities
• Facebook 360, YouTube Spatial Audio, Google Resonance
• 360° videos

#zylia #gameaudio #6dof #objectbased #scenebased #audio #volumetric #gamedevelopment #GameDevelopersConference #GDC2021 #GDC

​Zylia in collaboration with Poznań Philharmonic Orchestra showed first in the world navigable audio in a live-recorded performance of a large classical orchestra. 34 musicians on stage and 30 ZYLIA 3’rd order Ambisonics microphones allowed to create a virtual concert hall, where each listener can enact their own audio path and get a real being-there sound experience.
 
ZYLIA 6 Degrees of Freedom Navigable Audio is a solution based on Ambisonics technology that allows recording an entire sound field around and within any performance imaginable. For a common listener it means that while listening to a live-recorded concert they can walk through the audio space freely. For instance, they can approach the stage, or even step on the stage to stand next to the musician. At every point, the sound they hear will be a bit different, as in real life. Right now, this is the only technology like that in the world.

6 Degrees of Freedom in Zylia’s solution name refers to 6 directions of possible movement: up and down, left and right, forward and backward, rotation left and right, tilting forward and backward, rolling sideways. In post-production, the exact positions of microphones placed in the concert hall are being mirrored in the virtual space through the ZYLIA software. When it is done, the listener can create their own audio path moving in the 6 directions mentioned above and choose any listening spot they want.

​6DoF sound can be produced with an object-based approach – by placing pre-recorded mono or stereo files in a virtual space and then rendering the paths and reflections of each wave in this synthetic environment. Our approach, on the contrary, uses multiple Ambisonics microphones – this allows us to capture sound in almost every place in the room simultaneously. Thus, it provides a 6DoF sound which is comprised only of real-life recorded audio in a real acoustic environment.
 
How was it recorded?
* Two MacBooks pro for recording
* A single PC Linux workstation serving as a backup for recordings
* 30 ZM-1S mics – 3rd order Ambisonics microphones with synchronization
* 600 audio channels –  20 channels from each ZM-1S mic multiplied by 30 units
* 3 hours of recordings, 700 GB of audio data

To be able to choose the best versions of performances, the Orchestra played nine times the Overture and eight times the Aria with three additional overdubs.
Simultaneously to the audio recording, we were capturing the video to document the event. The film crew placed four static cameras in front of the stage and on the balconies. One cameraman was moving along the pre-planned path on the stage. Additionally, we have put two 360 degrees cameras among musicians.
Our chief recording engineer made sure that everything was ready – static cameras, moving camera operator, 360 cameras and recording engineers – and then gave a sign to the Conductor to begin the performance. When the LED rings on the 30 arrays had turned red everybody knew that the recording has started.

A large amount of data make it possible to explore the same moment in endless ways. Recording all 19 takes of two music pieces resulted in storing 700 GB of audio. The entire recording and preparation process was documented by the film with several cameras. Around 650 GB of the video has been captured. In total, we have gathered almost 1,5 TB of data.

First, we had to prepare the 3D model of the stage. The model of the concert hall was redesigned, to match the dimensions in real life. Then, we have placed the microphones and musicians according to the accurate measurements. When this was done, specific parameters of the interpolation algorithm in the ZYLIA 6DoF HOA Renderer had to be set. The next task was the most difficult in post-production - matching the real camera sequences with the sequences from the VR environment in Unreal Engine. After this painstaking process of matching the paths of virtual and real cameras, a connection between Unreal and Wwise was established. In this way, we had the possibility to render the sound of the defined path in Unreal - just as if someone was walking there in VR. Last, but not least - was to synchronize and connect the real and virtual video with the desired audio.

The outcome of this project is presented in “The Walk Through The Music” movie, where we can enter the music spectacle from the audience position and move around artists on the stage. 

​You can also watch the “Making of” movie to get more detailed information on how the setup looked like. 

In these crazy times, we musicians face many new challenges. We spend more time creating at home – we play in here, write new songs, record and mix. It is, however, a good time to learn new audio techniques and polish the old ones.
There is a tool that will allow you to take your first easy steps in sound post-processing, so you could bring yourself closer to the world of professional musicians.

ZYLIA Music set consists of one spherical microphone array (with 19 microphones hidden inside!) and easy in use ZYLIA Studio software. That’s it! This is all you need to make your home recordings in studio quality.

​Everything is simple and intuitive. The software will guide you step by step through the recording process. You don't need to be familiar with all the cables, as well as, with recording interfaces and techniques. You don't need to know how to properly position the microphones to record the sound correctly. This recording studio will do everything for you. You just have to play well ;-)

If you want to set free in full your music creativity and explore the sound design topic, we have a PRO plugin for you. This will take you to the next level of sound post-processing. You will be able to experiment with Ambisonics sound and mix the 360-degree scene using virtual microphone technology. You also have a wide range of spatial presets at your disposal. Invaluable, especially nowadays, is the possibility to stream 3D audio in binaural format, so the one which mirrors the way our ears hear.

Don't waste your time scrolling through boring videos on the Internet. Get started making beautiful music!
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Good luck!

​What does it mean? We are working on technology that gives people the possibility to listen to a concert or live performance from any point in the audio scene.  With our technology you are able to record an audio scene from different points of the space – the center of the stage, from the middle of a string quartet, audience, or backstage. Audio recorded in such a way can be used together with virtual reality projections and allow the user to freely move around the space giving the natural experience of audio scene and the possibility to listen to it from different perspectives.

The first step of test recordings was to install 9 3rd order Ambisonics microphone arrays on the same level and record musicians playing their performance. Such an approach allowed the listener to move around those 9 points and listen to their music from different perspectives. However, microphones placement on a single level introduced limitations in terms of audio resolution in the vertical plane.

Since we like challenges we decided to increase the number of microphones to 53 and build an installation on five different levels. It allowed us to freely move in every direction of the recorded scene in a truly immersive experience. The second idea behind this test setup was to check the limits of Ambisonics recordings in order to achieve a fully navigable audio scene. We placed the microphones arrays densely in the recorded scene and we received a spatial audio image of very high resolution.

We used 53 19-channel mic arrays – which gave us 1007 audio channels recorded simultaneously. Microphones were connected to a USB hub and the recordings were operated via a single laptop.

The audio recorded from each microphone array was converted to 3rd order Ambisonics using our ZYLIA Ambisonics Converter plugin (it can be done in real-time or offline).  After the recording, we used our interpolation software. This software is a MaxMSP plugin, that generates 3rd order Ambisonics spheres based on the signal from all microphones in the position you are at the moment. When you put your headphones and VR headset and move around the space the algorithm in MaxMSP takes your position and interpolates 3D sound in the position you are at the moment.

We used 3rd order Ambisonics microphone arrays. It is important because the higher the order the more precision we get in the spatial localization of sound around the listener. We are able to recreate the sound with a very high spatial resolution which influences the audio quality - an extremely important aspect for listeners.

With this simple approach, you can record the natural audio scene for your VR/AR productions and use it right away without complicated work-flow in post-production. You can record live events and stream audio directly to the listener giving him the possibility to freely choose the position in this real-time recorded space for an ultimate immersive audio experience.

We are happy to share the ProSound News product review featuring ZYLIA hardware and software. 

"Zylia Studio software is surprisingly good and is hands-down the easiest way I’ve encountered to record multiple musicians in a single room."

"Recording with the ZM-1 is an enjoyable process, and the quality is surprisingly good. Tracks are natural and smooth, and the isolation between instruments is impressive."

​What would happen if on a rainy and cloudy day, during a walk along a forest path, you could move into a completely different place thousands of kilometers away from you? Putting the goggles on would get you into a virtual reality world, you would find yourself on a sunny island in the Pacific Ocean, you would be on the beach, admiring the scenery and walking among the palm trees listening to the sound of waves and colorful parrots screeching over your head.
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It sounds unrealistic, but such goals are determined by the latest trends in the development of Augmented / Virtual Reality technology (AR / VR). Technology and content for full VR or 6DoF (6 Degrees-of-Freedom) rendered in real time will give the user the opportunity to interact and navigate through virtual worlds. To experience the feeling of "full immersion" in the virtual world, realistic sound must also follow a high-level image. Therefore, only each individual sound source present in virtual audio landscape provided to the user as a single object signal can reliably reflect both the environment and the way the user interacts with it.

There are many possibilities of using a 6DoF VR technology. You can imagine exploring a movie plan in your own pace. You could stroll between the actors, look at the action from different sides, listen to any conversations and paying attention to what is interesting only for you. Such technology would provide really unique experiences.

​A wide spectrum of virtual reality applications drives the development of technology in the audio-visual industry. Until now, image-related technologies have been developing much faster, leaving the sound far behind. We have made the first attempts to show that 6DoF for sound is also achievable.

​It's extremely challenging to record high-quality sound from many sources present in the sound scene at the same time. We managed to do this using nine ZYLIA ZM-1 multi-track microphone arrays evenly spaced in the room.

In our experiment the sound field was captured using two different spatial arrangements of ZYLIA ZM-1 microphones placed within and around the recorded sound scenes. In the first arrangement, nine ZYLIA ZM-1 microphones were placed on a rectangular grid. Second configuration consisted of seven microphones placed on a grid composed of equilateral triangles.

​Microphone signals were captured using a personal computer running GNU/Linux operating system. Signals originating from individual ZM-1 arrays were recorded with the specially designed software. 

​We recorded a few takes of musical performance with instruments such as an Irish bouzouki (stringed instrument similar to the mandolin), a tabla (Indian drums), acoustic guitars and a cajon.

To present interesting possibilities of using audio recorded with multiple microphone arrays we have created a Unity project with 7 Ambisonics sources. In this simulated environment, you will find three sound sources (our musicians) represented by bonfires among whom you can move around. Experiencing fluent immersive audio becomes so natural that you can actually feel being inside of this scene.

​During exploration experiments, MPEG Standardization Committee has realized that there is a lack of test material for audio and video experiments into MPEG-I Immersive Video. Our recordings have been accepted as a reference material in MPEG Standardization Committee. Each of the experts involved in standardization works on MPEG-I can now use the Zylia recordings to develop and test audio technologies for VR/AR applications.