Re: remove known sample from audio

[Jan Stary <hans@stare.cz>]

On Sep 25 12:26:36, molkko@gmail.com wrote:
> What is the best way to subtract a known sample from given audio i.e.
> extract/reconstruct the original.wav from final.wav when final.wav has been
> created with commands:
> 
> sox knownsample.wav knownsample_delay_gain.wav pad <X> 0 vol <Y>
> sox -m original.wav knownsample_delay_gain.wav final.wav

First of all, by "sample", you mean "signal",
not some one sample value, right?

> original.wav is not anymore available. knownsample.wav and final.wav are
> available.

Do you also have knownsample_delay_gain.wav ?

> pad delay and the vol parameter are known _roughly_ (X =~10ms,
> Y=~0.1)

So you want to reconstruct original.wav from the mix
AND one of the originals - that's quite different than reconstructing
from just the mix.wav (which I doubt would be possible).

> PS1, I can reconstruct the original with the process below but this method
> is very cumbersome:
> repeat {
> come up with some guessed X and Y
> sox knownsample.wav knownsample_delay_gain.wav pad <X> 0 vol -<Y> // is
> also inverted
> sox -m -v 1 original.wav -v 1 knownsample_delay_gain.wav final.wav stat
> } until RMS amplitude reported by stat has reached local minimum

You said you no longer have original.wav, but you are using it here.
So what's there to reconstruct?

> PS2, The original problem is a two musical instruments recorded
> simultaneously in the same space. They have their own mics but the other
> instrument is audible in each recording. I want to remove the "wrong
> instrument" from each recording and have clean audio for both instruments.

https://en.wikipedia.org/wiki/Spill_(audio)
This should be your starting paragraph, not PS2.

So show us the files: the mix (final.wav) and
the non-delayed bleeding instrument (knownsample.wav).
Also, name them more plainly (guitar, trumpet, mix - or whatever).

It will be much easier to help you then.


	Jan



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