[ProAudio] Mastering and monitoring for spatial audio

cheater cheater cheater00social at gmail.com
Sat Apr 17 18:07:22 PDT 2021

That makes sense!

If you wanted true "sounds the same to everyone" 3D sound, then head
size is the least of your problems. You'd need accurate HRTF for the
person listening. See what Mark Cerny, the tech lead behind
PlayStation 5, had to say about this. Starts at 38:25 (in case the
link doesn't take you there):


Measuring a person's HRTF can be challenging to say the least, but it
can be done. I bet David has mics small enough... the question is who
will agree to put their head in the pincer machine.

On Sat, Apr 17, 2021 at 10:54 PM CW Frymire
<cwfrymire at modernminstrel.com> wrote:
> 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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