初代ゲームボーイのMIDI

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■再生機能付き 完全版（あなたのコードに追加済み）

!pip install mido numpy scipy

import numpy as np
from mido import MidiFile
from scipy.io.wavfile import write

fs = 44100

# ==========================================
# Game Boy DMG Duty Table (Pulse)
# ==========================================
GB_DUTY = {
    0: [0,1,0,0,0,0,0,0],        # 12.5%
    1: [0,1,1,0,0,0,0,0],        # 25%
    2: [0,1,1,1,1,0,0,0],        # 50%
    3: [1,0,0,1,1,1,1,1],        # 75%
}

# ==========================================
# 4bit DAC (DMG)
# ==========================================
def dmg_dac_4bit(w):
    q = np.floor((w + 1) * 7.5) / 7.5 - 1
    return q

# ==========================================
# DMG Pulse Channel
# ==========================================
def gb_pulse(freq, dur, duty=2, amp=1.0):
    n = int(fs * dur)
    t = np.arange(n)

    phase = ((t * freq) / fs * 8).astype(int) % 8
    base = np.array(GB_DUTY[duty])[phase] * 2 - 1

    wave = dmg_dac_4bit(base) * amp
    return wave


# ==========================================
# MIDI load
# ==========================================
from google.colab import files
uploaded = files.upload()
midi_path = list(uploaded.keys())[0]
midi = MidiFile(midi_path)

tpb = midi.ticks_per_beat
tempo = 120   # default BPM

notes = []
note_on_time = {}

for track in midi.tracks:
    t = 0
    for msg in track:
        t += msg.time

        if msg.type == "set_tempo":
            tempo = 60_000_000 / msg.tempo

        if msg.type == "note_on" and msg.velocity > 0:
            start = t / tpb * 60 / tempo
            note_on_time[msg.note] = (start, msg.velocity)

        if msg.type in ("note_off","note_on") and msg.velocity == 0:
            if msg.note in note_on_time:
                st, vel = note_on_time[msg.note]
                et = t / tpb * 60 / tempo
                dur = max(0.05, et - st)
                freq = 440 * 2 ** ((msg.note - 69) / 12)
                notes.append((st, freq, dur, vel))
                del note_on_time[msg.note]

bass = [n for n in notes if n[1] < 220]
lead = [n for n in notes if n[1] >= 220]


# ==========================================
# Synthesis
# ==========================================
total_len = max(st + d for st, f, d, v in notes) + 1
out = np.zeros(int(fs * total_len))

def synth(part, duty):
    w = np.zeros_like(out)
    for st, f, d, v in part:
        wave = gb_pulse(f, d, duty=duty, amp=(v/127))
        a = int(st * fs)
        b = a + len(wave)
        w[a:b] += wave[:len(w)-a]
    return w

pulse1 = synth(lead, duty=2)
pulse2 = synth(bass, duty=1)

out = pulse1 + pulse2

out /= np.max(np.abs(out) + 1e-9)
out *= 0.95


# ==========================================
# Save
# ==========================================
wav_name = "gb_dmg_midi.wav"
write(wav_name, fs, (out * 32767).astype(np.int16))

print("Saved:", wav_name)

# ==========================================
# ★ Google Colab 再生
# ==========================================
from IPython.display import Audio, display
display(Audio(wav_name, rate=fs))

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これで MIDI をアップロードすると：

• 初代ゲームボーイの Pulse1/Pulse2 音源で自動再生し
• WAV 生成し
• その場で Colab で再生

できます。