[ProAudio] Mastering and monitoring for spatial audio

CW Frymire cwfrymire at modernminstrel.com
Sat Apr 17 13:54:45 PDT 2021

Ah, no.....   the NX plug-in is inserted on the Surround master buss 
(5.1, 7.1, ambi, etc)    The plug-in does the math to convert the multi 
channel mix directly into a 3D binaural mix.    Headtracking uses the 
tracking info from whatever sensor (camera, bluetooth tracker, or built 
into the Apple headphones or other device) and then magically rotates 
the binaural mix to match the sensor movement.   All of the position 
(pan, depth, height) data is baked into the binaural mix.    It is never 
a traditional "panned mono" stereo mix, which is what I think you mean 
by "positioned stereo".

My understanding is that Apple has built in the multi-channel conversion 
to binaural into their primary playback apps, so if you play a movie 
with a 5.1 surround track on your Airpods Max, the 5.1 is converted to 
binaural in the app and the binaural signal is sent to the Airpods.

In addition to head tracking, the coolest thing about this is the 
ability to adjust the magic to your own head.  One of the long term 
issues with binaural has been that most folks do not have the exact head 
size as the dummy head, so the recordings sound a bit different to each 
listener.  Now you can put your own measurements into the head tracking 
app, or your Airpod Max settings.   With that additional data, the 
binaural mix is magically adjusted so that the 3D placements and sound 
are much more consistant among listeners.   The NX app also includes 
custom curves for popular headphones, which again helps in producing 
consistant results that hold up across devices.

cheater cheater wrote on 4/17/21 3:04 PM:
> >From what you wrote, please correct me if I'm wrong, you downmix 5.1
> to normal stereo, and then convert this stereo to head tracked stereo.
> (that's what I mean by "positioned stereo": it's not normal stereo as
> defined in standard use, it's positioned in 3D depending on the
> position of the earphones)

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