DTMFDECODE(1) BSD Reference Manual DTMFDECODE(1)
dtmfdecode - decodes DTMF tones from A-law audio data
dtmfdecode
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>. MirBSD #10-current February 15, 1999 1