[LAU] Audio to midi, finding notes from an mp3

Chris Cannam cannam at all-day-breakfast.com
Mon Sep 24 04:40:48 EDT 2007

On Monday 24 September 2007 00:43, david wrote:
> Matthias Schönborn wrote:
> > On Sunday 23 September 2007 15:05:56 Simon Williams wrote:
> >> Does anyone know of a program which will convert audio to midi?
> >> Maybe that's a little ambitious. What about something that will show
> >> which notes are being played or what key the audio is in?
> >>
> >> I have some mp3s which I want to play along to, but I have no idea what
> >> key they are in or what notes are being played. The tracks move too
> >> quickly for me to pick out the notes.

Sonic Visualiser (http://www.sonicvisualiser.org) is very suitable for this 
sort of thing.  It allows you to loop sections and slow them down, there are 
plugins (see http://www.vamp-plugins.org/download.html -- the ones using Paul 
Brossier's aubio library are obvious candidates) to help with pitch and key 
estimation, and you can look at the frequency content in a spectrogram.  It 
won't do very meaningful audio-to-MIDI though.

> There are a lot of programs that can turn audio recordings into MIDI
> files. They all seem to be closed-source, proprietary, pay-money Windows
> programs. My band leader and I tried out some of them (they can run
> under WINE, typically, and my band leader uses Windows, anyway).
> Not a single one produced anything usable! They were able to identify
> notes, and output them as MIDIs, but the output was pretty useless:
> every note of every instrument on the same staff.

That's not a bad result for such a tough problem.  Even monophonic note 
tracking is tricky, depending a great deal on the instrument.  Note tracking 
in a dense polyphonic mixture is much harder (if it's possible at all).


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