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pysynth.py
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pysynth.py
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#!/usr/bin/env python
"""
##########################################################################
# * * * 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
"""
import sys
assert sys.version >= '3.3', "This program does not work with older versions of Python.\
Please install Python 3.3 or later."
from demosongs import *
from mkfreq import getfreq
pitchhz, keynum = getfreq(pr = True)
##########################################################################
#### 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
from mixfiles import mix_files
def make_wav(song,bpm=120,transpose=0,pause=.05,boost=1.1,repeat=0,fn="out.wav", silent=False):
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=b''
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)
##########################################################################
if silent == False:
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 and silent == False:
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(b'')
f.close()
print()
##########################################################################
# 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")