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pysynth.py
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pysynth.py
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#!/usr/bin/env python
# -*- coding: latin-1 -*-
"""
##########################################################################
# * * * PySynth * * *
# A very basic audio synthesizer in Python (www.python.org)
#
# Martin C. Doege, 2009-04-07 (mdoege@compuserve.com)
##########################################################################
# Based on a program by Tyler Eaves (tyler at tylereaves.com) found at
# http://mail.python.org/pipermail/python-list/2000-August/049968.html
##########################################################################
# 'song' is a Python list (or tuple) in which the song is defined,
# the format is [['note', value]]
# Notes are 'a' through 'g' of course,
# optionally with '#' or 'b' appended for sharps or flats.
# Finally the octave number (defaults to octave 4 if not given).
# An asterisk at the end makes the note a little louder (useful for the beat).
# 'r' is a rest.
# Note value is a number:
# 1=Whole Note; 2=Half Note; 4=Quarter Note, etc.
# Dotted notes can be written in two ways:
# 1.33 = -2 = dotted half
# 2.66 = -4 = dotted quarter
# 5.33 = -8 = dotted eighth
"""
# Example 1: The C major scale
song1 = [
['c',4],['d',4],['e',4],['f',4],['g',4],['a',4],['b',4],['c5',2],['r',1],
['c3',4],['d3',4],['e3',4],['f3',4],['g3',4],['a3',4],['b3',4],['c4',2],['r',1],
['c1*', 1], ['c2*', 1], ['c3*', 1], ['c4*', 1], ['c5*', 1], ['c6*', 1], ['c7*', 1], ['c8*', 1],
]
# Example 2: Something a little more patriotic
song2 = (
('g', -8), ('e', 16),
('c*', 4), ('e', 4), ('g', 4),
('c5*', 2), ('e5', -8), ('d5', 16),
('c5*', 4), ('e', 4), ('f#', 4),
('g*', 2), ('g', 8), ('g', 8),
('e5*', -4), ('d5', 8), ('c5', 4),
('b*', 2), ('a', -8), ('b', 16),
('c5*', 4), ('c5', 4), ('g', 4),
('e*', 4), ('c', 4),
)
# Example 3: Beginning of Nocturne Op. 9 #2 by F. Chopin
song3 = (
('bb', 8),
('g5*', 2), ('f5', 8), ('g5', 8), ('f5', -4), ('eb5', 4), ('bb', 8),
('g5*', 4), ('c5', 8), ('c6', 4), ('g5', 8), ('bb5', -4), ('ab5', 4), ('g5', 8),
('f5*', -4), ('g5', 4), ('d5', 8), ('eb5', -4), ('c5', -4),
('bb*', 8), ('d6', 8), ('c6', 8), ('bb5', 16), ('ab5', 16), ('g5', 16), ('ab5', 16), ('c5', 16), ('d5', 16), ('eb5', -4),
)
# Example 4: J.S. Bach: Bourrée (from BWV 996)
song4_rh = (
('e', 8), ('f#', 8),
('g*', 4), ('f#', 8), ('e', 8), ('d#*', 4), ('e', 8), ('f#', 8),
('b3*', 4), ('c#', 8), ('d#', 8), ('e*', 4), ('d', 8), ('c', 8),
('b3*', 4), ('a3', 8), ('g3', 8), ('f#3*', 4), ('g3', 8), ('a3', 8),
('b3*', 8), ('a3', 8), ('g3', 8), ('f#3', 8), ('e3*', 4), ('e', 8), ('f#', 8),
('g*', 4), ('f#', 8), ('e', 8), ('d#*', 4), ('e', 8), ('f#', 8),
('b3*', 4), ('c#', 8), ('d#', 8), ('e*', 4), ('d', 8), ('c', 8),
('b3*', 4), ('a3', 8), ('g3', 8), ('g3*', 32), ('f#3*', 32), ('g3*', 32), ('f#3*', 32), ('g3*', 32), ('f#3*', 32), ('g3*', 32), ('f#3*', 6.4), ('g3', 8), ('g3*', -2),
)
# version without the trill:
# ('b3*', 4), ('a3', 8), ('g3', 8), ('f#3*', -4), ('g3', 8), ('g3*', -2),
song4_lh = (
('g2', 8), ('f#2', 8),
('e2*', 4), ('a2', 4), ('b2', 4), ('a2', 4),
('g2*', 4), ('f#2', 4), ('e2', 4), ('f#2', 4),
('g2*', 4), ('a2', 4), ('b2', 4), ('a2', 4),
('g2*', 4), ('b2', 4), ('e2', 8), ('f#2', 8), ('g2', 8), ('f#2', 8),
('e2*', 4), ('a2', 4), ('b2', 4), ('a2', 4),
('g2*', 4), ('f#2', 4), ('e2', 4), ('f#2', 4),
('g2*', 4), ('c3', 4), ('d3', 4), ('d3', 4),
('b2*', -2),
)
##########################################################################
# Compute and print piano key frequency table
##########################################################################
pitchhz = {}
keys_s = ('a', 'a#', 'b', 'c', 'c#', 'd', 'd#', 'e', 'f', 'f#', 'g', 'g#')
keys_f = ('a', 'bb', 'b', 'c', 'db', 'd', 'eb', 'e', 'f', 'gb', 'g', 'ab')
if __name__ == '__main__':
print "Piano key frequencies (for equal temperament):"
print "Key number\tScientific name\tFrequency (Hz)"
for k in range(88):
freq = 27.5 * 2.**(k/12.)
oct = (k+9) // 12
note = '%s%u' % (keys_s[k%12], oct)
if __name__ == '__main__':
print "%10u\t%15s\t%14.2f" % (k+1, note.upper(), freq)
pitchhz[note] = freq
note = '%s%u' % (keys_f[k%12], oct)
pitchhz[note] = freq
##########################################################################
#### Main program starts below
##########################################################################
# Some parameters:
# Beats (quarters) per minute
# e.g. bpm = 95
# Octave shift (neg. integer -> lower; pos. integer -> higher)
# e.g. transpose = 0
# Pause between notes as a fraction (0. = legato and e.g., 0.5 = staccato)
# e.g. pause = 0.05
# Volume boost for asterisk notes (1. = no boost)
# e.g. boost = 1.2
# Output file name
#fn = 'pysynth_output.wav'
# Other parameters:
# Influences the decay of harmonics over frequency. Lowering the
# value eliminates even more harmonics at high frequencies.
# Suggested range: between 3. and 5., depending on the frequency response
# of speakers/headphones used
harm_max = 4.
##########################################################################
import wave, math, struct
def make_wav(song,bpm=120,transpose=0,pause=.05,boost=1.1,repeat=0,fn="out.wav"):
f=wave.open(fn,'w')
f.setnchannels(1)
f.setsampwidth(2)
f.setframerate(44100)
f.setcomptype('NONE','Not Compressed')
bpmfac = 120./bpm
def length(l):
return 88200./l*bpmfac
def waves2(hz,l):
a=44100./hz
b=float(l)/44100.*hz
return [a,round(b)]
def sixteenbit(x):
return struct.pack('h', round(32000*x))
def asin(x):
return math.sin(2.*math.pi*x)
def render2(a,b,vol):
b2 = (1.-pause)*b
l=waves2(a,b2)
ow=""
q=int(l[0]*l[1])
# harmonics are frequency-dependent:
lf = math.log(a)
lf_fac = (lf-3.) / harm_max
if lf_fac > 1: harm = 0
else: harm = 2. * (1-lf_fac)
decay = 2. / lf
t = (lf-3.) / (8.5-3.)
volfac = 1. + .8 * t * math.cos(math.pi/5.3*(lf-3.))
for x in range(q):
fac=1.
if x<100: fac=x/80.
if 100<=x<300: fac=1.25-(x-100)/800.
if x>q-400: fac=1.-((x-q+400)/400.)
s = float(x)/float(q)
dfac = 1. - s + s * decay
ow=ow+sixteenbit((asin(float(x)/l[0])
+harm*asin(float(x)/(l[0]/2.))
+.5*harm*asin(float(x)/(l[0]/4.)))/4.*fac*vol*dfac*volfac)
fill = max(int(ex_pos - curpos - q), 0)
f.writeframesraw((ow)+(sixteenbit(0)*fill))
return q + fill
##########################################################################
# Write to output file (in WAV format)
##########################################################################
print "Writing to file", fn
curpos = 0
ex_pos = 0.
for rp in range(repeat+1):
for nn, x in enumerate(song):
if not nn % 4:
print "[%u/%u]\t" % (nn+1,len(song))
if x[0]!='r':
if x[0][-1] == '*':
vol = boost
note = x[0][:-1]
else:
vol = 1.
note = x[0]
try:
a=pitchhz[note]
except:
a=pitchhz[note + '4'] # default to fourth octave
a = a * 2**transpose
if x[1] < 0:
b=length(-2.*x[1]/3.)
else:
b=length(x[1])
ex_pos = ex_pos + b
curpos = curpos + render2(a,b,vol)
if x[0]=='r':
b=length(x[1])
ex_pos = ex_pos + b
f.writeframesraw(sixteenbit(0)*int(b))
curpos = curpos + int(b)
f.writeframes('')
f.close()
print
def mix_files(a, b, c, chann = 2, phase = -1.):
f1 = wave.open(a,'r')
f2 = wave.open(b,'r')
f3 = wave.open(c,'w')
f3.setnchannels(chann)
f3.setsampwidth(2)
f3.setframerate(44100)
f3.setcomptype('NONE','Not Compressed')
frames = min(f1.getnframes(), f2.getnframes())
print "Mixing files, total length %.2f s..." % (frames / 44100.)
d1 = f1.readframes(frames)
d2 = f2.readframes(frames)
for n in range(frames):
if not n%(5*44100): print n // 44100, 's'
if chann < 2:
d3 = struct.pack('h',
.5 * (struct.unpack('h', d1[2*n:2*n+2])[0] +
struct.unpack('h', d2[2*n:2*n+2])[0]))
else:
d3 = ( struct.pack('h',
phase * .3 * struct.unpack('h', d1[2*n:2*n+2])[0] +
.7 * struct.unpack('h', d2[2*n:2*n+2])[0]) +
struct.pack('h',
.7 * struct.unpack('h', d1[2*n:2*n+2])[0] +
phase * .3 * struct.unpack('h', d2[2*n:2*n+2])[0]) )
f3.writeframesraw(d3)
f3.close()
##########################################################################
# Synthesize demo songs
##########################################################################
if __name__ == '__main__':
print
print "Creating Demo Songs... (this might take about a minute)"
print
# SONG 1
make_wav(song1, fn = "pysynth_scale.wav")
# SONG 2
make_wav(song2, bpm = 95, boost = 1.2, fn = "pysynth_anthem.wav")
# SONG 3
make_wav(song3, bpm = 132/2, pause = 0., boost = 1.1, fn = "pysynth_chopin.wav")
# SONG 4
# right hand part
make_wav(song4_rh, bpm = 130, transpose = 1, pause = .1, boost = 1.15, repeat = 1, fn = "pysynth_bach_rh.wav")
# left hand part
make_wav(song4_lh, bpm = 130, transpose = 1, pause = .1, boost = 1.15, repeat = 1, fn = "pysynth_bach_lh.wav")
# mix both files together
mix_files("pysynth_bach_rh.wav", "pysynth_bach_lh.wav", "pysynth_bach.wav")