NAME
dtmfdecode —
decodes DTMF tones from
A-law audio data
SYNOPSIS
DESCRIPTION
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.
EXAMPLES
The command:
will print a "1" to stdout.
STANDARDS
ITU Recommendations G.711
AUTHORS
The
dtmfdecode utility was written by
Poul-Henning Kamp
<
phk@freebsd.org>. This
man page was written by
Hellmuth Michaelis
<
hm@freebsd.org>.