analogue2midi

[Synthaholic AKA sPEW]

Something like a GR50 guitar synth does this.  One of the hardest
problems to tackle is what is called 'tracking'.  Tracking is the
speed and accuracy with which the converter can evaluate pitch,
velocity and other expressive parameters and spit them out as MIDI
messages.  One of the nastiest pieces if this is pitch conversion.  I
believe that Roland uses dv/dt or slew rate on the first quarter cycle
of a picked string to get a rough estimate of the pitch.  This pitch
estimate is used to trigger the synth and begin producing the attack
portion of the sound (which is usually less dependent on pitch).  The
GR50 then continuously monitors the pitch of the vibrating string and
sends pitchwheel messages to correct any error in the original
estimate.  Even though this sounds like it should be really fast,
there is still a noticable delay especially on the lower 2 strings.  I
have reduced this for myself by replacing the lower two strings with
smaller diameter strings and tuning up an octave.  This allows normal
fingering, but takes some getting used to the rather unexpected octave
change.

My $0.02 for what it's worth

On Wed, 12 Feb 1997 19:51:51 -0800, you wrote:

>What about ideas in order to implement not a pitch2midi device 
>but a polyphonic analogue2midi converter. I have been doing some thinking 
>of it, nevertheless I'd like to hear your opinions, technical or not.
>
>	thanks :-)
>
>	fernandofonseca at mail.telepac.pt
>

- Scott Gravenhorst (Synthaholic)     www.concentric.net/~chordman

Programming: The Ultimate Computer Game. | Windows 95: The Ultimate
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