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DTMFDECODE(1)               General Commands Manual              DTMFDECODE(1)

     dtmfdecode - decodes DTMF tones from A-law audio data


     dtmfdecode is part of the isdn4bsd package and is used to detect DTMF
     tones in the audio stream.

     It reads audio G.711 A-law coded data from stdin and outputs the detected
     numbers values as ASCII characters to stdout.

     The detector is implemented as 8 narrow band-pass filters realized with
     an integer double-cross recursive algorithm.  Various ad-hoc methods are
     employed to provide hysteresis and anti-bounce for the detected signals.

     The command:

           dtmfdecode < beep.al

     will print a "1" to stdout.

     ITU Recommendations G.711

     The dtmfdecode utility was written by Poul-Henning Kamp
     <phk@freebsd.org>.  This man page was written by
     Hellmuth Michaelis <hm@freebsd.org>.

NetBSD 8.0                     February 15, 1999                    NetBSD 8.0