This page will guide you through decoding an existing Ambisonics recording.
The guide will decode a recording made on the Sennheiser AMBEO Ambisonics microphone in Reaper.
Note: Reaper is recommended as other DAWs may restrict the number of track channels or enforce busses with fixed channels, which can break the link between multichannel ambisonics tracks and the decoder bus.
Set up the mixer
Recall ambisonics scene
Connect the mixer to the Mac via USB.
In the scenes menu on the Yamaha TF1 mixer, recall the "ambi2try-withDCA" scene.
See this page for more details.
Set up master bus
Configure master outputs
In a new Reaper project, ensure Yamaha TF is selected as the audio device.
Navigate to the "ROUTE" button on the master fader. It should look like a series of parallel diagonal lines. Change "Track Channels" to 12, and set the output source to "1-12" on the bottom left dropdown (fig 1.1)
Configure AIIRADecoder
Navigate to the "FX" button on the master fader. Add the "AIIRADecoder" plugin.
Click on import, and select Steinert213-try3.json. It should be saved on the desktop. See this page for more details.
Under "Calculate Decoder" ensure decoder order is set to match however many channels your recording has. Calculate decoder.
e.g. for a 4-channel recording, you would set order to 1st, then calculate decoder.
Click on each "Noise" button to make sure each speaker is connected.
Set up new track
Add a new track
Double click in the left pane to create a new track. This will be our main track.
Fig 1.1 Master output configuration
Fig 1.2 A to B format converter plugin settings
Configure outputs
Navigate to the fader menu. Click on the routing button (diagonal lines).
Ensure "Master send channels from/to" checkbox is selected.
Set track channels to however many channels are in the recording. For example, the Sennheiser AMBEO microphone has 4 channels, so track channels should be set to 4.
Set up ambisonics format converter
On the main track, add the "dearVR AMBI MICRO" plugin. This will convert our A-format tracks to B-format for the decoder. More details on what this means can be found in the dropdown below this section.
Select "A-Format" under the input settings, and "B-Format" under the output. Other settings can be configured to your recording specifications. The settings shown in fig 1.2 are for a 4-channel recording on an upright AMBEO microphone.
Note that the ambisonics order in this plugin corresponds to the number of channels in your recording. In this 4-channel example, the A-to-B conversion happens in 1st order.
Import your tracks
Drag your multichannel track onto this new track. It should now be ready for listening.
You can visually monitor your outputs by adding "EnergyVisualiser" to the master bus.
4. Optional steps
Setting up separate tracks for each channel
If your recordings are on separate tracks, or if you'd like to process each track separately, add new tracks underneath the main track.
To explode a single multichannel recording, you can also right click on your track, select "Item Processing > Explode multichannel audio"
Change the main track to a bus by clicking on the folder icon on its bottom left.
Add your tracks to the separate channels
In the routing menu of each individual track, check the output destination. Ensure each track is sent from "1" to whatever channel they correspond to.
For example, for a four-channel recording, the first track should be sending 1 -> 1, the second would be 1 -> 2, the third 1 -> 3 and the last 1 -> 4.
Here's why we convert from A-Format to B-Format:
A-Format is what comes directly off the microphone. The AMBEO microphone has four capsules pointing in different directions, each capsule recording its own raw audio track. By themselves, these four channels don't give you a usable 3D soundfield - they're just four separate mic signals.
B-Format combines the raw mic signals into a single standardized oackage that Ambisonics decoders can understand. Once in B-format, you can rotate it, decode it to headphones or speaker arrays, and render it consistently across different playback setups.
Decoders typically only understand B-format. As such, you must first convert A -> B using a converter plugin before decoding the tracks into a speaker setup.