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Author Topic: Only chromatic Midi data?  (Read 1127 times)

Offline Mathias

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Only chromatic Midi data?
« on: September 09, 2017, 02:29:34 PM »
Can the midi sprout only send midi data as full midi numbers like 60, 62, or can it be changed to send in between midi-numbers like 62.456 and thereby a more precise reading of the plants frequency?

Hope you can help   :)

Offline sam

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Re: Only chromatic Midi data?
« Reply #1 on: September 10, 2017, 09:30:21 AM »
In MIDI there is the possibility to do micro tuning.  One method would use the base note and pitch bend by a small amount, MIDI Pitch bend has a much more fine resolution.  See the 'Easy Way:' below...

The MIDI Sprout is programed detect change through an algorithm and output MIDI notes (chromatic) in proportion to the amount of change recorded.   It is quite possible to change or replace this with a different algorithm which outputs different types of MIDI data, there is even a control voltage output (low passed PWM) which can smoothly provide 1023 specific values between 0 and VCC.

The concept of 'reading the frequency of the plant' is not exactly how the Sprout works.  Here we are detecting the conductivity between two probes which are attached to the plant's leaf.  This is a 'point in time' measurement, many measurements are made a fast as possible and the data is stored.  Overtime there are fluctuations in the conductivity measured, but don't think of this as a periodic frequency in an audible sense - the rate at which measurements are being read makes a large difference to the density (kinda like calculus filling the area under a curve with the smallest possible slices/readings).  The MIDI notes which are output when a change is detected are calculated as whole numbers. 

If you consider what aspect of the data you are trying to measure, Delta/Min/Max/ MaxchangeRate/ StandardDeviationChangeRate, it should not be hard to come up with an algorithm that outputs microtunings.  And you will need a MIDI synthesizer which is capable of reading and playing those modified notes.

Most people want to have a more simple scale or limit the range of the notes, your idea of microtuning is something which i tried early on but abandoned due to issues with musicality and the challenge in perceiving polyphonic microtonal changes versus macroscopic notes.

Easy Way:  The MIDI sprout outputs Notes on Channel 1 along with MIDI CC 80.  If you are using a computer or perhaps AbletonLive, you can map the MIDI CC80 to control the pitch bend of your synth.  This will present a fine tuned slew to each of the notes.  The note pitch represents the amount of change (delta), the CC 80 represents the rate of change over time.