NAME    [Toc]    [Back]

     dtmfdecode -- decodes DTMF tones from A-law audio data

SYNOPSIS    [Toc]    [Back]

     dtmfdecode

DESCRIPTION    [Toc]    [Back]

     The dtmfdecode utility 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.

EXAMPLES    [Toc]    [Back]

     The command:

	   dtmfdecode < beep.al

     will print a "1" to stdout.

STANDARDS    [Toc]    [Back]

     ITU Recommendations G.711

AUTHORS    [Toc]    [Back]

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


FreeBSD 5.2.1		       February 15, 1999		 FreeBSD 5.2.1