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signal_strength.py
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signal_strength.py
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#!/usr/bin/python
## This is an example of a simple sound capture script.
##
## The script opens an ALSA pcm for sound capture. Set
## various attributes of the capture, and reads in a loop,
## Then prints the volume.
##
## To test it out, run it and shout at your microphone:
from neopixel import *
import alsaaudio, time, audioop, sys
class StrengthController():
def __init__(self, strip):
self.strip = strip
pixels = []
pixels.append([8, 9, 10, 32, 33, 34])
pixels.append([7, 11, 31, 35])
pixels.append([6, 12, 30, 36])
pixels.append([5, 13, 29, 37])
pixels.append([4, 14, 28, 38])
pixels.append([3, 15, 27, 39])
pixels.append([2, 16, 26, 40])
pixels.append([1, 17, 18, 19, 20, 21, 22, 23, 24, 25])
self.pixels = pixels
# Open the device in nonblocking capture mode. The last argument could
# just as well have been zero for blocking mode. Then we could have
# left out the sleep call in the bottom of the loop
self.inp = alsaaudio.PCM(alsaaudio.PCM_CAPTURE,alsaaudio.PCM_NONBLOCK)
# Set attributes: Mono, 8000 Hz, 16 bit little endian samples
self.inp.setchannels(1)
self.inp.setrate(8000)
self.inp.setformat(alsaaudio.PCM_FORMAT_S16_LE)
# The period size controls the internal number of frames per period.
# The significance of this parameter is documented in the ALSA api.
# For our purposes, it is suficcient to know that reads from the device
# will return this many frames. Each frame being 2 bytes long.
# This means that the reads below will return either 320 bytes of data
# or 0 bytes of data. The latter is possible because we are in nonblocking
# mode.
self.inp.setperiodsize(160)
def start(self):
while True:
# Read data from device
l,data = self.inp.read()
if l:
# Return the maximum of the absolute value of all samples in a fragment.
for i in range(106, 146):
self.strip.setPixelColor(i, 0)
try:
volume = audioop.max(data, 2)
except:
volume = 3
scaled = volume / 5000
if scaled > 8:
scaled = 8
scaled = scaled - 1
if scaled < 0:
scaled = 0
pix = self.pixels[scaled]
for pixel in pix:
index = 105 + pixel
self.strip.setPixelColor(index, Color(100, 100, 100))
self.strip.show()
time.sleep(.001)