Re: Software for chord identification

[robert gjerdingen <r-gjerdingen@xxxxxxxxxxxxxxxx>]

On Sep 7, 2005, at 5:21 PM, Eric Jacobs wrote:

> If I know what chord is being played (call this "actual chord") - and I
> do know what chord should be played (call this "ideal chord") - I can
> adjust the recording speed as required to reproduce the ideal chord.

Eric,

	I agree with Leon that "chord" may not be the best entry point to 
determine original pitch and therefore turntable speed.  Since chords 
are aggregates of pitches, and since knowing the "ideal" chord means 
knowing the ideal pitches, and since early recordings strongly 
foreground the vocalist or soloist, it would probably be sufficient to 
isolate a known "ideal" pitch and run it through a 
fundamental-pitch-extraction algorithm.

	While it might be possible to have a high degree of confidence in the 
ideal pitch of early classical instrumental recordings, confidence 
would be much lower in popular or classical vocal recordings.  In both 
realms pitch was often adjusted up or down for the comfort (or vantity) 
of the singer.  Nonetheless, if you really do know the ideal pitch, 
then the degree of error in pitch determination would probably be less 
than for other measures (e.g., vibrato rate).  On a different tack, if 
your recordings are of dance music, you might be able to use 
high-confidence recordings (e.g., movie soundtracks) to estimate what 
the Italians once called the _tempo jiusto_, or the "right tempo" for a 
given genre of dance (e.g., foxtrot, tango, etc.).

	Currently the very best software for comparing the actual pitch to the 
ideal pitch is known as a musician :)

Bob Gjerdingen
Northwestern Univ.