ZYLIA 6 Degrees of Freedom Navigable Audio
​Frequently Asked Questions

Below you will find a list of basic questions and answers regarding the ZYLIA 6DoF Navigable Audio solution.

6 degrees of freedom audio recording

What distance between the ZYLIA microphones is required to represent the sound space accurately?

Our internal experiments and listening tests have shown that the optimal distance between the microphones is 1.5 to 2 meters. This placement gives the best results when it comes to interpolation and sound source localization. However, putting the microphones up to 10 meters from one another can still give satisfactory spatial resolution. Of course, still, the smaller distance there is, the higher spatial resolution can be achieved. 
It all depends on the creative idea and effects you want to acheve.

Why audio synchronization is so important for 6DoF recordings?

To create a 6DoF audio experience we need to use several Ambisonics microphones recording the sound scene from many different perspectives. For a proper 6DoF playback all these recordings need to be synchronized with each other. To achieve that, in the software, they are trimmed at the beginning - so that they start exactly at the same moment and if necessary they are resampled  – so that the ends match as well.

​What are the longest USB cables that can be used for the recording without signal loss?

The 3-meter micro USB cables can be connected with 10-meters long USB extensions, that can be connected to the active USB hub, which can also be connected to another 10-meter USB extension, giving an approximate length of 23 meters (75.5 feet).

Can the 6 Degrees of Freedom audio be achieved with the ZM-1 microphone as well or only with the ZM-1S?

​The 6 Degrees of Freedom audio can be achieved only with the ZM-1S microphone because only this model supports external synchronization. Each ZM-1S microphone has 20 audio channels – 19 for recording signals from microphone capsules and 1 for receiving the analog synchronization impulses (the mini-jack input). Additionally, the ZM-1S contains a dedicated chip that allows for the connection of multiple ZM-1S through the USB interface in a single computer. It is possible to connect around 10 ZM-1S to a single USB 2.0 interface, because of the data transfer speed limit. However, if a computer has more USB controllers, then it is possible to aggregate more signals.

How the audio is being align with the time code using the USB hub?

​ZYLIA ZM-1S microphone has an additional input for analog time code so it’s easy to synchronize all the microphone arrays. You can also connect external recording systems. It is, however, worth pointing out that ZYLIA is not just a microphone, but it is actually an audio card too. It means that, if you are sending a time code into the audio card in a setup of, for example, 7 microphones, you need to think of it like it is 7 audio cards you need to time synchronize.

Check the differences between both models.

HOW CAN WE MONITOR DURING THE RECORDING?

​In the ZYLIA 6DoF Recording application, we can do live monitoring on every array. This is done in the way that we can listen from the two opposite capsules of the chosen microphone.

Is it possible to turn off the LED ring light to hide the microphones on a recording set?

Yes, the LED ring light on the microphone can be dimmed or completely switched off if necessary.

6DoF audio post-processing

What are the advantages of the ZYLIA 6DoF production system over more traditional multi microphone recording techniques and audio object mixing?

There are several advantages of using the ZYLIA 6DoF production system instead of traditional solutions. One of them is lower processing power consumption because we are using only live-recorded audio without doing any simulations. Another great benefit is the faithful reproduction of the real acoustics of the place, which can be precisely captured with the ZYLIA microphones. Because it is so accurate, it creates truly immersive feeling, especially that the system delivers high-resolution, spatial audio. It is a very detailed representation of the sound sphere, allowing a listener to easily locate all sounds that surround them.

However, the greatest thing in working with Higher Order Ambisonics is that you can prepare the main content and later mix it down or render it in all sorts of formats that allow many different experiences. It can be, for instance, static binaural rendering or interactive 3D audio. 

With the 6DoF tool, we can really navigate in space and move our listener towards the aspect of musical presentation that we want to highlight.
Also, when we record with a Higher-Order Ambisonics (HOA) microphones and we are close enough to a source, the instrument, for instance, is not a point source anymore. If we have a spot microphone, the source is also a spot source.  But with the HOA microphone, the source suddenly has spatial resolution and can be heard differently from different perspectives.

How accurate is mapping of the individual microphone locations in the software?

The accuracy of mapping depends on the accuracy of the measurements made during the recording session. We recommend measuring the distance between all the microphones on the recording set and using these data to create a grid that can be later mirrored in the software.

Is it possible to reduce the size of the recordings?

It is possible to compress the files after recording, using, for example, OGG compression. This should decrease their size by 10 to 20 times. These compressed files can be used in the VR application. On our website, there are available two versions of the VR application with Poznań Philharmonic Orchestra recordings: one with uncompressed and the other with compressed audio.  The compressed version weighs around 3 GB so it is significantly lighter compared to the full version.

Is there a way of using ZYLIA 6DoF HOA Renderer in a game engine environment like Unity or Unreal Engine? How 6DoF audio recordings can be delivered to this kind of engine?

ZYLIA 6 Degrees of Freedom Higher Order Ambisonics Renderer is a MAX/MSP plugin available for MAC OS and Windows. It allows processing and rendering the ZYLIA Navigable 3D Audio content. With this plugin users can play back the synchronized Ambisonics files, change the listener’s position, and interpolate multiple Ambisonics spheres. The plugin can be connected with the Unity or Unreal through the OpenSound Control (OSC). However, it is also available in the Wwise plugin, which allows developers to use 6DoF audio in various game engines. In the Wwise version the connection is established through RTCP.

A lot of VR applications are made within Unity or Unreal Engine. Unity, however, doesn’t support Higher Order Ambisonics. What middleware can be used in this case?

In this case, we recommend using Wwise from Audiokinetic. It supports up to 6th order Ambisonics. ZYLIA 6DoF Renderer is available in the Wwise version and it perfectly integrates with Unity or Unreal engine. Wwise is a professional tool that is used not only in games production and VR but also in movie production.

Is there a way to edit and mix 6DoF in DAW or do I need to go through a game environment?

​For editing and mixing 6DoF content, we can use any DAW that supports multichannel tracks (at least 16), for example, Reaper. However, the playback requires using the MAX/MSP plugin, which can be connected with DAW through the OpenSound Control (OSC). That will allow sending messages with the information about the position of the listener from Reaper to MAX/MSP and creating a path.

How can I connect 360° sound with multiple 360 cameras? ​

If we would like to have multiple 360° views with corresponding 360° audio in each of them, then we would have to make as many HOA mixes as we have cameras. The other use case would be using the same Ambisonics mix in every camera. In general, the workflow is a manner of creating the necessary number of HOA mixes, editing all the videos, and combining the audio and video together.

6DoF audio playback

Can we stream 6DoF sound having each viewer navigate individually through sound?

Right now, video sharing platforms like Facebook or YouTube do not allow each viewer to navigate individually through the audio scene. This kind of fully immersive, navigable experience can be achieved through the VR application for a smartphone, PC, or VR headset. 

However, on Facebook or YouTube, we can share multi-point 360° audio-video content. In this case, multi Ambisonics capture points would be combined with multi 360° cameras. The viewer would be switched between the cameras by an operator but they would be able to rotate and look around in each spot by themselves.  The sound they hear wound of course correspond with that movement.

Can I use a 3DoF VR headset to experience 6DoF audio and move around the space using a controller or touchpad?

​3DoF VR headset allows a person to look around in the VR environment by rotating their head along 3 axes  (yaw, pitch, and roll). However, you may use a controller or touchpad to include translational movements in your experience as well (sway, heave, surge) and in this way move freely around the space.

Are all 3rd order signals used at the same time or only those that are closest to the listening position? i.e. how high are the CPU costs for running 6DoF in the game?

​During rendering we use all of the inputs, but even though the CPU cost is very small comparing to the object-based sound. The algorithm doesn’t contain any heavy operation like ray-tracing or reflection simulation. This allows reproducing the realistic sound even on limited platforms like Oculus Quest. The application which uses 30 signals from the recordings of the Poznan Philharmonic Orchestra is available on the Oculus App Lab. Also, we are preparing a demonstration where we compare the 6DoF approach with the object-based sound in games. The more sound objects you have the higher usage of CPU is, but in our approach, the CPU usage is constant, independent of the number of objects. Overall, our algorithm consumes about 100 to 10.000 times less CPU than the object-based approach.