midi_file.py

import os

from mido import MidiFile
import numpy as np
import string

# 120 beat per minute / temp0 : 50,000 microseconds per bit
# 1beat 당 220개의 ticks
# 1beat : 0.5초
# 1개 tick당 0.5초/220
cv1 = MidiFile("classic.wav.midi", clip=True)


def msg2dict(msg):
    result = dict()
    if "note_on" in msg:
        on_ = True
    elif "note_off" in msg:
        on_ = False
    else:
        on_ = None
    result["time"] = int(
        msg[msg.rfind("time") :]
        .split(" ")[0]
        .split("=")[1]
        .translate(str.maketrans({a: None for a in string.punctuation}))
    )

    if on_ is not None:
        for k in ["note", "velocity"]:
            result[k] = int(
                msg[msg.rfind(k) :]
                .split(" ")[0]
                .split("=")[1]
                .translate(str.maketrans({a: None for a in string.punctuation}))
            )
    return [result, on_]


def switch_note(last_state, note, velocity, on_=True):
    # piano has 88 notes, corresponding to note id 21 to 108, any note out of this range will be ignored
    result = [0] * 88 if last_state is None else last_state.copy()
    if 21 <= note <= 108:
        result[note - 21] = velocity if on_ else 0
    return result


def get_new_state(new_msg, last_state):
    new_msg, on_ = msg2dict(str(new_msg))
    new_state = (
        switch_note(
            last_state, note=new_msg["note"], velocity=new_msg["velocity"], on_=on_
        )
        if on_ is not None
        else last_state
    )
    return [new_state, new_msg["time"]]


def track2seq(track):
    # piano has 88 notes, corresponding to note id 21 to 108, any note out of the id range will be ignored
    result = []
    last_state, last_time = get_new_state(str(track[0]), [0] * 88)
    for i in range(1, len(track)):
        new_state, new_time = get_new_state(track[i], last_state)
        if new_time > 0:
            result += [last_state] * new_time
        last_state, last_time = new_state, new_time
    return result


def mid2arry(mid, min_msg_pct=0.1):
    tracks_len = [len(tr) for tr in mid.tracks]
    min_n_msg = max(tracks_len) * min_msg_pct
    # convert each track to nested list
    all_arys = []
    for i in range(len(mid.tracks)):
        if len(mid.tracks[i]) > min_n_msg:
            ary_i = track2seq(mid.tracks[i])
            all_arys.append(ary_i)
    # make all nested list the same length
    max_len = max([len(ary) for ary in all_arys])
    for i in range(len(all_arys)):
        if len(all_arys[i]) < max_len:
            all_arys[i] += [[0] * 88] * (max_len - len(all_arys[i]))
    all_arys = np.array(all_arys)
    all_arys = all_arys.max(axis=0)
    # trim: remove consecutive 0s in the beginning and at the end
    sums = all_arys.sum(axis=1)
    ends = np.where(sums > 0)[0]
    return all_arys[min(ends) : max(ends)]


result_array = mid2arry(cv1)