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>.
MirOS BSD #10-current February 15, 1999 1
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