How I reverse engineered a commercial spatial audio effect
epestr.com
epestr.com
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.
is this why i have to log in to an account to use Virtual Surround on gaming headsets
Do you still have a working demo anywhere? The link in your post seems to be down, and I'd be interested in hearing it.
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
And there is a way to toggle it: the icon which is orange can be tapped on and off, and you can adjust the "bass" which is built in with the ring around it. Also, it's likely to have no effect on voice, more complex arrangements will have an audible difference.
There is similarly an example on Wikipedia too, which got me interested: https://en.wikipedia.org/wiki/File:BinauralPaper.ogg.
My Jabra headphones don't seem to apply any processing by default, and I prefer how they sound with the processing. If your headphones already boost bass or apply another effect, stacking the processing can be grating (which I've experienced when I record a video and play that through the daemon running).
I guess it's a matter of taste. I just like music sounding as though it's coming from a little farther away, and I suppose the bass-boost might be what you're finding unpleasant.
I've made the default 20% in the page for now.
OP wants the `earwax` audio filter in ffmpeg.
It sounds very close to what I was going for, and feels much softer to hear. I wasn't able to find anything similar earlier with any search engine or an LLM.
To get the best possible results from equalization you need to do it by ear by comparison to a calibrated reference loudspeaker, but you can still get good results using other people's measurements. And there's no consensus what the best target curve is. Studio control rooms aren't anechoic chambers so "flat" won't necessarily give you the intended sound. You might find AutoEq useful:
I generally prefer no spatial processing, except in the case of 60s-style hard-panned stereo, which is intended for loudspeakers and does sound a lot better with the "earwax" filter or similar. "Precise and neutral" is a lot more difficult with loudspeakers, both because it's hard to keep distortion low when you're moving a lot of air, and because you have the off-axis response and room acoustics complicating things.
EQ can help a lot, but there are limits. The response curves you see are usually very smoothed and they’re only from one sample. The peaks and valleys and resonances can be narrow and can differ from unit to unit or even more from one manufacturing run to the next.
The response is also a function of the interface to your ear and leakage to the outside world. Some headphones are more sensitive than others.
I have a few high end headphones and I’ve tried a lot of the published EQs for all of them. In theory they should sound like they have the same frequency response but they still sound very different. Closer together when EQed, but you can tell they’re not the same.
I am an EQ proponent, but doing EQ on headphones doesn’t level the playing field so much that it only comes down to distortion.
The best case for EQ is in a sound controlled room for speakers when you can sit in the sweet spot and reflections and room effects are not a problem. Set up multiple sets of decent (distortion free) speakers in that environment with a moderate EQ and my listening skills aren’t good enough to identify differences most of the time.
Pretty much all audio is mixed for loudspeakers (in a room). It's fine if it is your preference but objectively the vast majority of music, film & etc sounds worse, or at least wrong with headphones. The main problem with these spatialization/binauralization techniques is that they are trying to model something that involves a deeply personal thing, the shape of your ears and head, and the way your brain interprets all that. They usually make these techniques with an average listener "head" in mind but if you are not lucky enough to fall in that average window the effect is likely sound bad or very fake.
I think it is meant to make jazz sound good. The eq-d bass and attenuated mids make a standup bass more apparent and the piano and vocals more present.
But it made me start to wonder if I started hating my favorite band: I was packing up to move this weekend and stumbled on my CD collection. Many Stereolab CDs. I played them in my basic acoustic waveguide radio. A slick bookshelf I inherited and rarely use.
45 minutes later I was telling myself "god this music sucks...just agonizing repetition." Turns out yes the motorik bass is repetitive...but the other key point of the band is the gentle singing and intricate delicate synth and organ melodies...all foreclosed on by some evil twin combo of an audio eng and marketer overindexing in mid low bass.
This fashion of cranking the base and the high end and removing the middle (simulating a subwoofer with some tiny speakers, basically) can't die fast enough.
I mean, fair play for the writer. If he wants it to sound that way he's of course free to do so. But this style is used a lot in concerts and open air amplification and I hate it.
My theory is that this style is popular with people playing their music too loud. If your ear feels 'blocked' after a while, your music is too loud.
One thing with this style is that, because it leaves the middle (speech) frequencies relatively empty, it feels less blocking. And the high base makes that it doesn't really sound tinny or harsh. But they high base cane easily damage your hearing still.
The more recent variant is "smiley curve" EQ - high at the extremes, drooping in the middle.
EQ can mess with transients, especially in the bass. You get more volume, but at the expense of some time smearing.
I also wonder about the opposite situation: someone turning the whole volume up because the bass doesn't sound loud enough, raising the other parts with it. Having the bass adjustable could help there. Some songs already have plenty of bass, so it makes sense to turn it down for those, and perhaps have a dynamic limiter when it gets excessive.
By "blocked" I meant the impression of music sounding too close to my ears, rather than my hearing feeling blocked after listening. Of course, feeling softer doesn't completely establish that it's safe either.
Now this does not contradict what you say, of course. It's very well possible that the human ear is less sensitive to bass and that people are underestimating the volume of bass.
Is a good solution? No, but he identified a problem and he solved it, not letting lack of domain knowledge stopping him. Respect.
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.
I was also wondering whether sending particular frequency bands to different sources would sound decent, and whether I could combine that with a downmix.
I've tried to figure it out to see if there are any modern equivalents, but I haven't been able to identify the feature. All I remember is that it was a single checkbox in the Windows driver settings, sometime in the '90s or early 2000s.
I've even downloaded the manuals for old Sound Blaster cards to look for it, but I can't remember which model I had. Creative Labs released so many variations of seemingly similar cards that narrowing it down feels almost impossible.
isnt it how Q-Sound worked back in the 80s?
Sound imaging method and apparatus https://patents.google.com/patent/US5105462A https://patents.google.com/patent/US5208860A
Stereo enhancement system including sound localization filters https://patents.google.com/patent/US5774556A
The particular coefficients made a considerable difference, which is why I ended up measuring an effect I already liked. I see some example values included in the patents here though, so those might be worth trying.
As for the effect, I was trying to get a particular effect I'd liked using earlier, rather than the most realistic spatial audio algorithm. The earwax effect mentioned elsewhere in the thread also sounds quite close to what I wanted. Posting this also worked as discovery, getting me some good suggestions for other effects to reverse engineer.