Reading piano notes on Python

问题

I'd like to listen to the port having my midi output device (a piano) with my RPi, running on Debian. I've looked into pygame.midi, I managed to listen to the port, but somehow can not extract all midi information. Please find code below [edited code snippet]

EDIT: Fixed, thanks a lot!

回答1:

First of all you need to find out which device-id your keyboard has inside pygame. I wrote this little function to find out:

import pygame.midi

def print_devices():
    for n in range(pygame.midi.get_count()):
        print (n,pygame.midi.get_device_info(n))

if __name__ == '__main__':
    pygame.midi.init()
    print_devices()

It looks something like this:

(0, ('MMSystem', 'Microsoft MIDI Mapper', 0, 1, 0))
(1, ('MMSystem', '6- Saffire 6USB', 1, 0, 0))
(2, ('MMSystem', 'MK-249C USB MIDI keyboard', 1, 0, 0))
(3, ('MMSystem', 'Microsoft GS Wavetable Synth', 0, 1, 0))

From the pygame manual you can learn that the first One inside this info-tuple determines this device as a suitable Input-Device. So let's read some data from it in an endless-loop:

def readInput(input_device):
    while True:
        if input_device.poll():
            event = input_device.read(1)
            print (event)

if __name__ == '__main__':
    pygame.midi.init()
    my_input = pygame.midi.Input(2) #only in my case the id is 2
    readInput(my_input)

That shows:

[[[144, 24, 120, 0], 1321]]

that we have a list of a list with 2 items:

• A list of midi-data and
• a timestamp

The second value is the one you're interested in. So we print it out as a note:

def number_to_note(number):
    notes = ['c', 'c#', 'd', 'd#', 'e', 'f', 'f#', 'g', 'g#', 'a', 'a#', 'b']
    return notes[number%12]

def readInput(input_device):
    while True:
        if input_device.poll():
            event = input_device.read(1)[0]
            data = event[0]
            timestamp = event[1]
            note_number = data[1]
            velocity = data[2]
            print (number_to_note(note_number), velocity)

I hope this helped. It's my first answer, I hope it's not too long. :)

来源：https://stackoverflow.com/questions/15768066/reading-piano-notes-on-python