soundlight (Python to Arduino)

soundlight.py

import alsaaudio, wave
import numpy
import serial
import time
import struct

MAX = 0

def arduino_soundlight():
    chunk      = 2**9  # Change if too fast/slow, I've tried 2**9 through 2**11
    scale      = 50    # Change if too dim/bright
    exponent   = 5     # Change if too little/too much difference between loud and quiet
    samplerate = 44100

    port = serial.Serial("/dev/ttyACM0", baudrate=57600, timeout=1.0)
    time.sleep(2)

    inp = alsaaudio.PCM(alsaaudio.PCM_CAPTURE)
    inp.setchannels(1)
    inp.setrate(samplerate)
    inp.setformat(alsaaudio.PCM_FORMAT_S16_LE)
    inp.setperiodsize(1024)

    while True:
        l, data = inp.read()
        try:
          levels = calculate_levels(data, chunk, samplerate)
          # Make it look better and send to serial
          print levels
          port.write(bytearray([4]))
          for level in levels:
              level = max(min(level / scale, 1.0), 0.0)
              level = level**exponent
              level = int(level * 255)
              port.write(bytearray([level]))
          port.write(bytearray([10]))
        except Exception:
          pass

def calculate_levels(data, chunk, samplerate):
    # Use FFT to calculate volume for each frequency
    global MAX

    # Convert raw sound data to Numpy array
    fmt = "%dH"%(len(data)/2)
    data2 = struct.unpack(fmt, data)
    data2 = numpy.array(data2, dtype='h')
    #data2 = numpy.fromstring(data, dtype='int16')

    # Apply FFT
    fourier = numpy.fft.fft(data2)
    ffty = numpy.abs(fourier[0:len(fourier)/2])/1000
    ffty1=ffty[:len(ffty)/2]
    ffty2=ffty[len(ffty)/2::]+2
    ffty2=ffty2[::-1]
    ffty=ffty1+ffty2
    ffty=numpy.log(ffty)-2

    fourier = list(ffty)[4:-4]
    fourier = fourier[:len(fourier)/2]

    size = len(fourier)

    # Add up for 3 lights
    levels = [sum(fourier[i:(i+size/3)]) for i in xrange(0, size, size/3)][:3]

    return levels

if __name__ == '__main__':
    arduino_soundlight()