Monitoring choices for Ambisonics outputs and mixdown to binaural

Hello!

I’m working in a game production that needs all sorts of project workflows from mixing mono exports to 3rd Order Ambisonics assets. I have to be able to switch between different channel formats, between 5.1.4 speakers to stereo headphones, often in one session.

The problems I have are related to how Nuendo handles its binaural decoding from either a 3OA group to a stereo group for exporting binaural 2-channel mixdown versions of a file or how the headphone monitoring part of the Control Room works.

How can I select a binaural decoder plugin of choice to be used in the monitoring? The only option Nuendo gives me is the Steinberg AmbiDecoder. That’s not a disaster but the plugin has a serious downside: It doesn’t support new, high-quality custom HRTF SOFA files! :frowning: If I could change the plugin itself, I could achieve much better sense of verticality for example. But I can’t change the decoder plugin. Is there something I’ve missed? The same goes for sending the signal from a 3rd Order Ambisonics mix group to a 2-channel mix group - the Send automatically gets Steinberg AmbiDecoder activated and the other choices in the Send Panning don’t even work. I would gladly try out different decoders to see how they work but Nuendo doesn’t let me do that. :frowning: Is this really the case? Has anyone else played around with Ambisonics and binaural stereo in Nuendo 10? The guide to select 3rd party plugins is for Nuendo 8 and doesn’t make sense to me.

I’m not in the studio right now and won’t be there this year. But as far as I know everything you want should be possible. AmbiDecoder does support SOFA files for example. Or are you referring to some different format than the one they support?

Cheers,
Alex

Hello Alex!

Unfortunately there are SOFAs that the AmbiDecoder doesn’t understand. For example SOFA files made with Genelec’s own modelling software. That’s why I’d like to try an alternative, 3rd party decoding solution.

You can install various Ambisonic decoders (for loudspeakers and headphones) on the master output, before the control room. That way you can export 3rd order un-decoded (decoder in bypass) or 3rd order decoded to the monitoring setup you need. I suggest you install the IEM and Aalto plug-ins for numerous decoding options.

https://plugins.iem.at & http://research.spa.aalto.fi/projects/sparta_vsts/

Hello Kewl, interesting. Do you mean like to have:

  1. Audio Tracks going to: 3rd Order Ambisonics Master Group (that’s how I’ve always worked with Nuendo - Tracks go to a Group, Group goes out an Out)
  2. That Master Group routed to a 3rd Order Ambisonics Output
  3. A decoder plugin enabled on that 3OA Output?

Yes.

But Kewl, how does this prevent Nuendo from activating its own AmbiDecoder plugin on the Phones channel? Do I also have to change the monitoring preset from 3OA to stereo when having a binaural decoder enabled in the 3OA output channel?

No, leave the Output Bus to 3OA. Don’t use the Control Room. Insert the decoder plug-in of your choice in the Output Bus. Activate either a loudspeaker decoder or a binaural decoder.

Ummm… okay. This is bad. :smiley: I have to be able to use Control Room to do other things. Sorry. Leaving it unused is too impractical.

How about when you want to mixdown the 3OA output into a binaural stereo file? How does that work? I have done downmixing through Sends between master group channels for a decade.

OK, use the control room. I was aiming for simple. Set two O3A monitor paths in the Control Room, one for loudspeakers and one for headphones. And always only one decoder active, either in the master or the control room.



Oh, this way looks good on paper at least! :slight_smile: Thanks Kewl, I’ll give this a shot.

Hey Kewl, the next issue I have is exporting a 2-channel binaural mixdown with this monitoring. The monitoring itself works great now since I can use the decoder of choice in the 3OA master, but how would you export a 2-track mixdown from this setup?

Have you tried selecting “L/R Channels” in the export window?

I’m on Nuendo 8.3.20 and selecting L/R Channels results in an empty stereo file: maybe it’s a bug or maybe it’s by design to not give the impression that selecting L/R Channels will, by itself, produce a stereo decoding (since there’s numerous ways to do an Ambisonic stereo decoding).

In any case, if selecting L/R Channels still produces silence (when the master bus is Ambisonic) in Nuendo 10, then activate the stereo decoder on the master bus and do the export without selecting L/R Channels. The resulting file will have 16 channels with signal on the first two channels and silence on the remaining fourteen. Use an external editor to delete the empty channels.

Hmm, I’m on version 10. This is worth testing at least! Otherwise I guess the way you suggested - exporting all the Ambisonics out channels and editing the rest of them out does work for sure, it’s just a bit slow. :slight_smile: Thanks again for your suggestions!

If necessary, using an external editor to delete unused channels is just one more step, really. You can use something like Sound Devices Wave Agent with its “Split/Combine” function.

Maybe I’m missing something, but don’t you just want the master bus to be stereo if you are exporting a binaural mix?
I would think you would send all your channels to a 3OA bus equipped with a binaural decoder, then send that 3OA bus to your (stereo) master.

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That’s exactly what I’m doing to export Ambisonic to a Binaural stereo. I use Nuendo’s Ambi Decoder for this.