audiotest.py

#!/usr/bin/env python

## recordtest.py
##
## This is an example of a simple sound capture script.
##
## The script opens an ALSA pcm forsound capture. Set
## various attributes of the capture, and reads in a loop,
## writing the data to standard out.
##
## To test it out do the following:
## python recordtest.py out.raw # talk to the microphone
## aplay -r 8000 -f S16_LE -c 1 out.raw


# Footnote: I'd normally use print instead of sys.std(out|err).write,
# but we're in the middle of the conversion between python 2 and 3
# and this code runs on both versions without conversion

import sys
import time
import getopt
import alsaaudio

alsacards = alsaaudio.cards()
print("alsacards =", alsacards)

secondcard = alsacards[1]
print("secondcard =", secondcard)

if not secondcard:
    print "No Mic Present"
    
card = secondcard 

filename = "test1.wav"

f = open(filename, 'wb')

# 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
inp = alsaaudio.PCM(alsaaudio.PCM_CAPTURE, alsaaudio.PCM_NONBLOCK, card)

# Set attributes: Mono, 44100 Hz, 16 bit little endian samples
inp.setchannels(1)
inp.setrate(16000)
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.
inp.setperiodsize(160)

loops = 1000000
while loops > 0:
    loops -= 1
    # Read data from device
    l, data = inp.read()
  
    if l:
        f.write(data)
        time.sleep(.001)