ffttest.py

# From http://julip.co/2012/05/arduino-python-soundlight-spectrum/
# Python 2.7 code to analyze sound and interface with Arduino
 
import pyaudio # from http://people.csail.mit.edu/hubert/pyaudio/
import serial  # from http://pyserial.sourceforge.net/
import numpy   # from http://numpy.scipy.org/
import audioop
import sys
import math
import struct
 
'''
Sources

http://www.swharden.com/blog/2010-03-05-realtime-fft-graph-of-audio-wav-file-or-microphone-input-with-python-scipy-and-wckgraph/
http://macdevcenter.com/pub/a/python/2001/01/31/numerically.html?page=2

'''
 
MAX = 0
NUM = 20
 
def list_devices():
    # List all audio input devices
    p = pyaudio.PyAudio()
    i = 0
    n = p.get_device_count()
    while i < n:
        dev = p.get_device_info_by_index(i)
        if dev['maxInputChannels'] > 0:
            print str(i)+'. '+dev['name']
        i += 1
 
def fft(): 
    chunk      = 2**11 # Change if too fast/slow, never less than 2**11
    scale      = 25    # Change if too dim/bright
    exponent   = 3     # Change if too little/too much difference between loud and quiet sounds
    samplerate = 44100 
 
    # CHANGE THIS TO CORRECT INPUT DEVICE
    # Enable stereo mixing in your sound card
    # to make you sound output an input
    # Use list_devices() to list all your input devices
    device   = 1 # Mic
    #device   = 4 # SF2
    
    p = pyaudio.PyAudio()
    stream = p.open(format = pyaudio.paInt16,
                    channels = 1,
                    rate = 44100,
                    input = True,
                    frames_per_buffer = chunk,
                    input_device_index = device)
    
    print "Starting, use Ctrl+C to stop"
    try:
        
        ser = serial.Serial(
            port='/dev/ttyS0',
            timeout=1
        )
        
        while True:
            data  = stream.read(chunk)
            # Do FFT
            levels = calculate_levels(data, chunk, samplerate)
 
            # Make it look better and send to serial
            for level in levels:
                level = max(min(level / scale, 1.0), 0.0)
                level = level**exponent 
                level = int(level * 255)
                #ser.write(chr(level))
                #sys.stdout.write(str(level)+' ')
            #sys.stdout.write('\n')
            #s = ser.read(6)
 
    except KeyboardInterrupt:
        pass
    finally:
        print "\nStopping"
        stream.close()
        p.terminate()
        #ser.close()
 
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')

    # 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 6 lights
    levels = [sum(fourier[i:(i+size/NUM)]) for i in xrange(0, size, size/NUM)][:NUM]
    
    return levels
 
if __name__ == '__main__':
    #list_devices()
    fft()