specturm.py

import ossaudiodev as oss
from numpy import fft
import math
import pygame
import pygame.surfarray as surfarray


d = oss.open('rw')
d.setfmt(oss.AFMT_U16_LE)
d.channels(1)
d.speed (44100)

buf_size = 4096
bins = 256

WIDTH = 500

pygame.init()
screen = pygame.display.set_mode((WIDTH, bins))
surf = pygame.display.get_surface()
px = surfarray.pixels2d(surf)


def power(c):
    return c.real * c.real + c.imag * c.imag

X = 0

while 1:
    x = d.read(buf_size)
    v = [-0.5 + (ord(x[2*i]) | ord(x[2*i+1])<<8) / 65536.0 for i in range(0,len(x)/2)]
    f = fft.fft(v)
    p = [power(c) for c in f]

    b = [0] * bins
    for i in range(0,bins):
        for j in range(0,buf_size/(4*bins)):
            b[i] += p[buf_size * i / (4*bins) + j]

    Xn = (X+1) % WIDTH

    for i in range(0,bins):
        k = int(255 * math.log(b[i]+1))
        if (k >= 255):
            k = 255
        px[X,bins-i-1] = k << 8
        k = 64
        px[Xn,bins-i-1] = (k<<16) | (k<<8) | k

    surfarray.blit_array(surf, px)

    pygame.display.flip()

    X += 1
    if (X >= WIDTH):
        X = 0
    d.write(x)