music secrets2

import math, wave, array
duration = 3 # seconds
freq = 440 # of cycles per second (Hz) (frequency of the sine waves)
volume = 1. # percent
data = [] # signed short integer (-32768 to 32767) data
sampleRate = 44100 # of samples per second (standard)
numChan = 1 # of channels (1: mono, 2: stereo)
dataSize = 2 # 2 bytes because of using signed short integers => bit depth = 16
numSamplesPerCyc = int(sampleRate / freq)
numSamples = sampleRate * duration

def num_to_wav(numbers):
    def SPLIT(x): return (x%256, (x/256)+256*(x<0))
    #return ''.join(map(lambda t: chr(t), reduce(lambda x,y: x+y, map(lambda x: SPLIT(x), numbers)))) - INEFFICIENT WAY
    return array.array('h', numbers).tostring()
def wav_to_num(stream):
    def JOIN(x): return x[0]+256*((x[1]-128)+128*(2*(x[1]<128)-1))
    temp=map(lambda x: ord(x), stream)
    return map(lambda x: JOIN(x), zip(temp[::2],temp[1::2]))
def write_wav(stream, path):
    #takes a stream of symbols and records a wav
    f = wave.open(path, 'w')
    f.setparams((numChan, dataSize, sampleRate, numSamples, "NONE", "Uncompressed"))
    f.writeframes(stream)
    f.close()
def read_wav(path):
    #takes a wav and return a stream
    f = wave.open(path, 'r')
    result=f.readframes(-1)
    f.close()
    return result

def add_lists(lists):
    '''adding multiple lists like vectors'''
    if len(set([len(lists[i]) for i in range(len(lists))]))<>1: raise ValueError('length is not synchronised')
    else: return [sum([x[i] for x in lists]) for i in range(len(lists[0]))]


def ADSR_env(x):
    if x<0.2: return 5*x
    if x<1: return 1-0.75*(x-0.2)
    if x<2: return 0.4
    return max(0, 0.4-0.4*(x-2.0))
def instrument(weigths, k=440, sampleRate=44100.):
    s=sum(weigths)
    weigths=[n/s for n in weigths]
    lists=[]
    for j in range(len(weigths)):
        division=[]
        for i in range(numSamples):
            argument=float(i)/sampleRate
            x=weigths[j] * math.sin(math.pi * 2 * argument * ((j+1)*k))
            component=int(-32767 * x * ADSR_env(argument))
            division.append(component)
        lists.append(division)
    return add_lists(lists)

#I'm adding 3 different waves of 440Hz, 660Hz and 220Hz.
for n in instrument([5.,4.,3.]): data.append(n)
write_wav(num_to_wav(data),'trial4.wav')
from time import*
t=time()
a=wav_to_num(read_wav('trial4.wav'))
print time()-t
print data==a