# Simple Python Spectrograph with PyGame

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**While thinking of ways to improve my QRSS VD high-definitions spectrograph software,** I often wish I had a better way to display large spectrographs. Currently I’m using PIL (the Python Imaging Library) with TK and it’s slow as heck. I looked into the PyGame project, and it seems to be designed with speed in mind. I whipped-up this quick demo, and it’s a simple case audio spectrograph which takes in audio from your sound card and graphs it time vs. frequency. This method is far superior to the method I was using previously to display the data, because while QRSS VD can only update the entire GUI (500px by 8,000 px) every 3 seconds, early tests with PyGame suggests it can do it about 20 times a second (wow!). With less time/CPU going into the GUI, the program can be more responsivle and my software can be less of a drain.

```
import pygame
import numpy
import threading
import pyaudio
import scipy
import scipy.fftpack
import scipy.io.wavfile
import wave
rate = 12000 # try 5000 for HD data, 48000 for realtime
soundcard = 2
windowWidth = 500
fftsize = 512
currentCol = 0
scooter = []
overlap = 5 # 1 for raw, realtime - 8 or 16 for high-definition
def graphFFT(pcm):
global currentCol, data
ffty = scipy.fftpack.fft(pcm) # convert WAV to FFT
ffty = abs(ffty[0:len(ffty)/2])/500 # FFT is mirror-imaged
# ffty=(scipy.log(ffty))*30-50 # if you want uniform data
print "MIN:t%stMAX:t%s" % (min(ffty), max(ffty))
for i in range(len(ffty)):
if ffty[i] < 0:
ffty[i] = 0
if ffty[i] > 255:
ffty[i] = 255
scooter.append(ffty)
if len(scooter) < 6:
return
scooter.pop(0)
ffty = (scooter[0]+scooter[1]*2+scooter[2]*3+scooter[3]*2+scooter[4])/9
data = numpy.roll(data, -1, 0)
data[-1] = ffty[::-1]
currentCol += 1
if currentCol == windowWidth:
currentCol = 0
def record():
p = pyaudio.PyAudio()
inStream = p.open(format=pyaudio.paInt16, channels=1, rate=rate,
input_device_index=soundcard, input=True)
linear = [0]*fftsize
while True:
linear = linear[fftsize/overlap:]
pcm = numpy.fromstring(inStream.read(
fftsize/overlap), dtype=numpy.int16)
linear = numpy.append(linear, pcm)
graphFFT(linear)
pal = [(max((x-128)*2, 0), x, min(x*2, 255)) for x in xrange(256)]
print max(pal), min(pal)
data = numpy.array(numpy.zeros((windowWidth, fftsize/2)), dtype=int)
# data=Numeric.array(data) # for older PyGame that requires Numeric
pygame.init() # crank up PyGame
pygame.display.set_caption("Simple Spectrograph")
screen = pygame.display.set_mode((windowWidth, fftsize/2))
world = pygame.Surface((windowWidth, fftsize/2), depth=8) # MAIN SURFACE
world.set_palette(pal)
t_rec = threading.Thread(target=record) # make thread for record()
t_rec.daemon = True # daemon mode forces thread to quit with program
t_rec.start() # launch thread
clk = pygame.time.Clock()
while 1:
for event in pygame.event.get(): # check if we need to exit
if event.type == pygame.QUIT:
pygame.quit()
sys.exit()
pygame.surfarray.blit_array(world, data) # place data in window
screen.blit(world, (0, 0))
pygame.display.flip() # RENDER WINDOW
clk.tick(30) # limit to 30FPS
```