How to read usb midi device input as music symbol by using c under linux system

[yingshaoxo]

// Linux MIDI input driver, protocol 1.0, there is no need to upgrade to protocol 2.0
// Author: yingshaoxo
// Run it in root shell
// gcc main.c -o main.run
// ./main.run

#include <sys/soundcard.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>

#define MIDI_DEVICE "/dev/midi1"
//#define MIDI_DEVICE "/dev/dmmidi1"
//#define MIDI_DEVICE "/dev/snd/midiC1D0"

int main(void) {
unsigned char inpacket[4];

// first open the sequencer device for reading.
int seqfd = open(MIDI_DEVICE, O_RDONLY);
if (seqfd == -1) {
printf("Error: cannot open %s\n", MIDI_DEVICE);
exit(1);
}

// now just wait around for MIDI bytes to arrive and print them to screen.
while (1) {
read(seqfd, &inpacket, sizeof(inpacket));

if (inpacket[0] == 144) {
printf("Pressed: ");
printf("%d\n", inpacket[1]);
} else {
printf("Released: ");
printf("%d\n\n", inpacket[1]);
}

//printf("strongth: %d", inpacket[2]);
}

return 0;
}

 

[SeaGtGruff]

As someone who once tried dabbling in MIDI app programming, it's nice to see someone else sharing like this.

 

[yingshaoxo]

I also made a python version:

# Author: yingshaoxo
# Python: 3.5
# midi usb protocol: 1.0  ;  There has no need to upgrade to 2.0

device_name = "/dev/midi1" # "/dev/dmmidi1" # "/dev/snd/midiC1D0"

while True:
    with open(device_name, "rb") as f:
        bytes_list = [None] * 3
        for index in range(3):
            bytes_list[index] = f.read(1)
        int_list = [int.from_bytes(one, "big") for one in bytes_list]

        the_key = int_list[1]
        the_strongth = int_list[2]
        print("              strongth:", the_strongth)
        if int_list[0] == 144:
            print("pressed:", the_key)
        else:
            print("released:", the_key)
            print("\n\n-------\n")
        print()