Windows 11 does that !! Videos playing on edge wont be heard by the folks on teams !!
Ask HN: How do browsers isolate internal audio from microphone input?
61–70 of 106 posts
Re: Ask HN: How do browsers isolate internal audio from microphone input?
#62"echo cancellation" is what its called, there's a few general purpose (non-ai) algos out there!
What's really interesting is I can get the algorithm to "mess up" by using external speakers a foot or two away from my computer's mic! Just that little bit of travel time is enough to screw with the algo.
Re: Ask HN: How do browsers isolate internal audio from microphone input?
#63Earlier quoted context omitted.
> Why does the OS not provide a way to do this? Some do. But you need to have a strong-handed OS team that's willing to push everybody towards their most modern and highly integrated interfaces and sunset their older interfaces. Not everybody wants that in their OS. Some want operating systems that can be pieced together from myriad components maintained by radically different teams, some want to see their API's/inte…
[flagged]
Huh? What's the aggression in characterizing the diverse landscape of operating systems and the users/developers who very reasonably may prefer each?
I think it's very good that we have so many options of what an operating system and its vendors/developers might prioritize, and that these differences in priority have consequential impact on how software gets built on each.
Re: Ask HN: How do browsers isolate internal audio from microphone input?
#64Earlier quoted context omitted.
Live video or audio chat is basically the only time you do want this. Granted, that’s a big chunk of microphone usage in practice, but any time you are doing higher fidelity audio recording and you have set up the inputs accordingly you absolutely do not want the artefacts introduced by this cancellation. DAWs, audio calibration, and even live audio when you’ve ensured the output cannot impact the recording all would…
> Live video or audio chat is basically the only time you do want this. If I'm recording a voice memo, or talking to an AI assistant, I would want this. Basically everything I can imagine doing with a PC microphone outside of (!) professional audio recording work. That last case is important and we agree there needs to be a way to turn it off. I think defaults are really important though.
My colleague works in a very quiet house, and has no need for noise cancelling. Sometimes, he has it turned on by accident, and the quality is much worse - his voice gets cut out, and volume of his voice goes up and down.
As you say, as long as either option is available, the only question is what the default should be.
Re: Ask HN: How do browsers isolate internal audio from microphone input?
#65Earlier quoted context omitted.
To spare others from googling: https://docs.pipewire.org/page_module_echo_cancel.html https://wiki.archlinux.org/title/PipeWire/Examples#Echo_canc... If you're still on pulseaudio for some reason, it ships with a similar module named "module-echo-cancel": https://www.freedesktop.org/wiki/Software/PulseAudio/Documen...
Huh, thanks. I was interested in this probably 6-8 years ago, and when I went digging the stackoverflow answer mentioned elsewhere in this thread [0] was as far as I got. I guess the tech has progressed since then. [0] https://stackoverflow.com/questions/21795944/remove-known-au...
It was there 8 years ago.
Re: Ask HN: How do browsers isolate internal audio from microphone input?
#66Windows 11 does this ! Videos playing on browser (edge, tested on youtube, linkedin videos) wont he heard to the meeting folks or folks on call in teams !
That's interesting. Following up, is there any reason why it wouldn't be possible for other browsers/applications? It seems like the operating system should be able to generally access the audio from any application
Re: Ask HN: How do browsers isolate internal audio from microphone input?
#67You can use a multidimensional Kalman filter to do this.
You can use a multidimensional Kalman filter to do many things
Re: Ask HN: How do browsers isolate internal audio from microphone input?
#68"echo cancellation" is what its called, there's a few general purpose (non-ai) algos out there! What's really interesting is I can get the algorithm to "mess up" by using external speakers a foot or two away from my computer's mic! Just that little bit of travel time is enough to screw with the algo.
Echo cancellation is often disabled if you have headphones plugged in, under the assumption that headphones won't be audible in the microphone, and it's better to disable it to avoid it degrading your microphone signal.
It might be that whatever program you're using doesn't know the difference between speakers and headphones (possibly because you're using the 3.5mm jack?)
Re: Ask HN: How do browsers isolate internal audio from microphone input?
#69The way this works (and I'm obviously taking a high level view here) is by comparing what is being played to what is being captured. There is an inherent latency in between what is called the capture stream (the mic) and the reverse stream (what is being output to the speakers, be it people taking or music or whatever), and by finding this latency and comparing, one can cancel the music from the speech captured. With…
For a little more context on negative feedback to those who want to know more (I believe this is what you're referring to?)
Here's a short historical interview with Harold Black from AT&T on his discovery/invention of the negative feedback technique for noise reduction. It's not super explanatory but a nice historical context: https://youtu.be/iFrxyJAtJ7U?si=8ONC8N2KZwq3Jfsq
Here's a more indepth circuit explanation: https://youtu.be/iFrxyJAtJ7U?si=8ONC8N2KZwq3Jfsq
IIRC the issue was AT&T was trying to get cross-country calling, but to make the signal carry further you needed a louder signal. Amplifying the signal also the distortion.
So Harold came up with this method that ultimately allowed enough signal reduction to allow calls to cross the country within the power constraints available.
For some reason I recall something about transmission about Denver being a cut off point before the signal was too degraded... But I'm too old and forgetful so I could be misremembering something I read a while ago. If anyone has more specific info/context/citations that'd be great. Since this is just "hearsay" from memory, but I think it's something like this.
Re: Ask HN: How do browsers isolate internal audio from microphone input?
#70The way this works (and I'm obviously taking a high level view here) is by comparing what is being played to what is being captured. There is an inherent latency in between what is called the capture stream (the mic) and the reverse stream (what is being output to the speakers, be it people taking or music or whatever), and by finding this latency and comparing, one can cancel the music from the speech captured. With…
This reminds me of: >The missile knows where it is at all times. It knows this because it knows where it isn't. By subtracting where it is from where it isn't, or where it isn't from where it is (whichever is greater), it obtains a difference, or deviation https://knowyourmeme.com/memes/the-missile-knows-where-it-is