[SOLVED] Get Audio Amplitude from ALSA Raspberry Pi

Issue

Im having an Airplay setup on my RasPi2 so i can play Music over wifi to my Raspberry Pi which is plugged in to my speakers (The software is called "shairplay"). Now i want to control some LED strips in sync with the audio amplitude that is currently played.

So my Question is: Is there any way i can get the current sound Amplitude of the played sound from ALSA? (preferable in Python)

Solution

This example uses maximum amplitude of the sound to detect noise using python. The same concept can be used to plot your amplitudes,

sox.sh

#!/bin/sh
filename=$1
duration=$2
arecord -q -f cd -d $duration -t raw | lame -r - $filename
sox $filename -n stat 2>&1 | sed -n 's#^Maximum amplitude:[^0-9]*\([0-9.]*\)$#\1#p'

soundcapture.py

#!/usr/bin/env python
#-*- coding: utf-8 -*-

import os
import subprocess
import sys
import re
import time

def main(args=None):

    try:
        while True:
            filename = time.strftime("%Y%m%d%H%M%S") + ".wav"
            proc = subprocess.Popen(['sh','sox.sh', filename, '5' ], stdout=subprocess.PIPE)
            result,errors = proc.communicate()
            amplitude=float(result)
            print amplitude
            if amplitude > 0.15:
                print 'Sound detected'
                #os.rename(filename, "data/" + filename)
            else:
                print 'No sound detected'
                #os.remove(filename)
    except KeyboardInterrupt:
        print('')
    finally:
        print('Program over')

if __name__ == '__main__':
    sys.exit(main(sys.argv[1:]) or 0)

Please checkout its github page for more details.

Answered By - Sufiyan Ghori

Answer Checked By - Mildred Charles (WPSolving Admin)