How I reverse engineered a commercial spatial audio effect

75 points - today at 3:21 PM

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fxtentacle today at 7:23 PM
It's been 12 years, but I once wrote a blog post on how my commercial spatial audio effect works: https://hajo.me/blog/2014/12/28/how-surround-sound-for-headp...

BTW, the resulting plugin was used during mastering of George Lucas' Red Tails, so I guess sound quality was fine ;)

My own Mac app has long since been discontinued (because Apple locked me out of the KExt permission), but I sold the tech and it lives on.

I keep wondering if I should build hardware headphones with the spatial audio inside, so it looks like Dolby Atmos to the TV but then does virtual surround sound on your headphones, but hardware has low-ish margins so I never found anyone willing to fund it, even though I already have a working prototype. Oh and the audio engineer who invented it has since been Grammy-nominated twice. And, well, Hollywood likes it. But still a tough sell towards investors.

andai today at 4:41 PM
Interesting article. I don't know much about sound processing but it reminded me of the Fruity Convolver in FL Studio, which can somehow apply the characteristics of one sound (an impulse?) to your audio stream. It has interesting effects built in, reverbs recorded in different unusual spaces, as well as guitar amps.

I would have liked to compare the audio clip from the beginning of the article, at the end too! Instead I had to record my own voice. And there doesn't seem to be a way to toggle the effect on and off? So it's a bit hard to get a sense of what it actually does.

This also reminds me of this cool mp3 from the 2000s — maybe it's on YouTube these days — called virtual barbershop, which was recorded with binaural microphones.

Edit: here she is! https://youtube.com/watch?v=IUDTlvagjJA

clzerv today at 4:31 PM
While I appreciate the effort and talent to pull this off, I find the results to be awful. I call this kind of overblown sound processing "Bose barf" since pretty much all Bose audio sounds like this, and it just grates on my nerves. Now TVs, Bluetooth speakers, headphones, etc. all seem to perform this kind of aggressive audio processing to overcome the limits of super cheap tiny drivers. It's getting hard to find devices which have a more neutral sound profile. All this audio processing makes music sound like it's coming out of a garden hose duct taped to a 1950's grade school hall speaker. I can't understand the appeal.
coldblues today at 6:41 PM
In hobbyist audiophile communities, there is a focus on downmixing Dolby Atmos music, which is 5.1 surround and has a much higher dynamic range. As an example: https://github.com/peqdb/macos

If you have Apple Music and you're on Windows, in the settings there is an option to downmix to stereo. Give it a try on any of the music here: https://helloatmos.app/library/

There are also people experimenting with spatial audio using HRTF, but I don't think it's very good for music.

haddr today at 7:24 PM
I wonder if author could follow something similar that is used to capture guitar amps to NAM models (Neural Amp Modeller), https://www.tone3000.com/capture
schleck8 today at 6:20 PM
I'm not convinced, the Nothing Ear spatial audio effect (which is pure postprocessing as far as I understand, since it's independent of codecs and containers) sounds a lot more realistic, and I doubt Nothing has the best algorithm in the field
jonathanstrange today at 8:30 PM
Sounds awful but I appreciate the technical aspects of the post.
aarunsoman today at 6:05 PM
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ofabioroma today at 7:55 PM
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