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Tk-applause-meter made me think about getting a sound-level direct from /dev/dsp, instead of relying on on an external application. This snippet just shows the basic idea.
#!/usr/bin/perl
use Audio::DSP;
#alsamixer must be setup right, AC'97 capture adjusts sensitivity,
#just turn it up to 100 for this to work as intended
($buf, $chan, $fmt, $rate) = (4096, 1, 16 , 8000);
$dsp = new Audio::DSP(buffer => $buf,
channels => $chan,
format => $fmt,
rate => $rate);
$dsp->init() || die $dsp->errstr();
my $samples = 1500;
my $num_tot = 0;
my $div_tot = 0;
# Record x samples of sound
for (1..$samples) {
#read 16 bits of raw data
my $data = $dsp->dread(16) || die $dsp->errstr();
my $num = unpack( 'v', $data );
#filter out baseline noise
if($num > 65000){next}else{
print "$num\n";
$num_tot += $num;
$div_tot += 32768; #gives a good average
}
}
$dsp->close();
print "\n\nAverage ",sprintf('%0.2f',$num_tot/$div_tot),"\n";