c/goertzel/dtmf.sh

   1 #!/bin/bash
   2 #This is sample implementation of DTMF decoder using my C implementation of Goertzel Algorithm
   3 #This is not very efficient or precise, it's just proof of concept
   4 #Usage example: arecord 2>/dev/null | ./dtmf.sh
   5
   6 tresh=3
   7 last='';
   8 ./goertzel -i -q -r 8000 -s 400 -t $tresh -f 697 -f 770 -f 852 -f 941 -f 1209 -f 1336 -f 1477 -f 1633 | while read line; do
   9         #echo "$line";
  10
  11         #Get time
  12         pos="$(echo "$line" | cut -f 1)";
  13
  14         #Get values for each tone
  15         a="$(echo "$line" | cut -f 2)";
  16         b="$(echo "$line" | cut -f 3)";
  17         c="$(echo "$line" | cut -f 4)";
  18         d="$(echo "$line" | cut -f 5)";
  19         e="$(echo "$line" | cut -f 6)";
  20         f="$(echo "$line" | cut -f 7)";
  21         g="$(echo "$line" | cut -f 8)";
  22         h="$(echo "$line" | cut -f 9)";
  23
  24         #Compare values to treshold
  25         test $a -gt $tresh && a=true || a=false
  26         test $b -gt $tresh && b=true || b=false
  27         test $c -gt $tresh && c=true || c=false
  28         test $d -gt $tresh && d=true || d=false
  29         test $e -gt $tresh && e=true || e=false
  30         test $f -gt $tresh && f=true || f=false
  31         test $g -gt $tresh && g=true || g=false
  32         test $h -gt $tresh && h=true || h=false
  33
  34         #echo "$pos: $a $b $c $d $e $f $g $h";
  35         state="$a$b$c$d$e$f$g$h";
  36
  37         #Test if tones changed since last time
  38         #echo test "$state" != "$last"
  39         test "$state" != "$last" && {
  40
  41                 #DTMF Table
  42                 $a && {
  43                         $e && echo -n '1'
  44                         $f && echo -n '2'
  45                         $g && echo -n '3'
  46                         $h && echo -n 'A'
  47                 }
  48                 $b && {
  49                         $e && echo -n '4'
  50                         $f && echo -n '5'
  51                         $g && echo -n '6'
  52                         $h && echo -n 'B'
  53                 }
  54                 $c && {
  55                         $e && echo -n '7'
  56                         $f && echo -n '8'
  57                         $g && echo -n '9'
  58                         $h && echo -n 'C'
  59                 }
  60                 $d && {
  61                         $e && echo -n '*'
  62                         $f && echo -n '0'
  63                         $g && echo    '#'
  64                         $h && echo -n 'D'
  65                 }
  66
  67         }
  68
  69         last="$state"
  70
  71 done