[music-dsp] polyphonic autotune

[Eric Brombaugh]

On 09/14/2010 02:54 PM, Conley, Dylan wrote:
> Greetings,
>
> I have been toying with the idea of a polyphonic autotune.  That is, I'd like to correct the pitch of a single track with multiple voices or signals.  I understand the technical difficulty in such a thing.  While a series of bandpass filters would allow for easy separation of simple sine wave signals, I am more interested in advanced source separation algorithms to separate, say, the voices of a barbershop quartet, or the keys of a grand piano.  I have read of methods for detecting pitch in polyphonic signals but have not read anything that details how to separate the distinct voices.  Any leads would be greatly appreciated.

Do a websearch on "Celemony Melodyne" - this software does just what 
you're talking about with it's 'Direct Note Access' feature. It was all 
the rage a few years ago at Musikmesse when there was a bit of 
controversy over how/if it actually worked and seems to have dropped 
into the background now that it appears it actually does.

Obviously it's not an easy problem, but it appears to have been solved. 
Of course Celemony isn't saying how it works...

Eric