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import bisect
import math
import struct
import sys
# Number of times to sample each second
bitrate = 44100
music = []
def process(notes, start, speed=1, gain=1, blend=0):
"""
Adds a list of notes to the music list
"""
t = start
for note in notes:
vol = 1
if len(note) == 4:
vol = note[3]
start = min(t, t + note[0] / speed)
end = max(t, t + note[0] / speed)
music.append((start, end + 16 * int(blend), note[1], note[2], vol * gain))
t = end
def freq(octave, step):
"""
Returns the frequency of a note
"""
return 55 * 2 ** (octave + step / 12 - 1)
def tone(f, t):
"""
Returns the intensity of a tone of frequency f sampled at time t
https://dsp.stackexchange.com/questions/46598/mathematical-equation-for-the-sound-wave-that-a-piano-makes
https://youtu.be/ogFAHvYatWs?t=254
"""
w = 2 * math.pi * f
Y = 0.6 * math.sin(w * t) * math.exp(-0.001 * w * t)
Y += 0.2 * math.sin(2 * w * t) * math.exp(-0.001 * w * t)
Y += 0.05 * math.sin(3 * w * t) * math.exp(-0.001 * w * t)
Y += Y * Y * Y
Y *= 1 + 16 * t * math.exp(-6 * t)
return Y
def at(t):
"""
Returns the total intensity of music sampled at time t
This is actually pretty efficient ngl
Because people usually don't have that many overlapping notes
"""
i = bisect.bisect(music, (t, 2**31))
ret = 0
for j in range(max(i - 32, 0), i):
m = music[j]
if m[1] > t:
ret += m[4] * tone(freq(m[2], m[3]), t - m[0])
return int(2**28 * ret)
def play(start, end):
"""
Print music from the start time to end time encoded in s32 to standard output
"""
music.sort()
for i in range(start * bitrate, end * bitrate):
sys.stdout.buffer.write(struct.pack("i", at(i / bitrate)))
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