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looking for a java framework do extract DTMF tones

hi all,
i need to write an application that listen for DTMF tones from
standard audio input (from the mic) and execute an action depending on
the digit extracted from the DTMF tone. Unfortunaly i have short time
to set up this application and i'm really new to this kind of problem
(sound analisys). I take a look at JTAPI but i don't have any
telephone in this context, i just have to analyze a normal sound
signal from the sound card. I found some applications on the net but
most of them need a modem and don't manage the input from the sound
card, the other are win apps and i cannot configure the actions.

I'm a java programmer so it would be nice if there's a library that i
can use and accept an audio stream in input and give the digit in
output ... if something like that doesn't exists i need at least a
java implementation of a DTMF decoder

thank you for your help

nemo
ne*****@libero.it
Jul 17 '05 #1
1 4056

"nemokid" <ne*****@libero.it> wrote in message
news:8a*************************@posting.google.co m...
hi all,
i need to write an application that listen for DTMF tones from
standard audio input (from the mic) and execute an action depending on
the digit extracted from the DTMF tone. Unfortunaly i have short time
to set up this application and i'm really new to this kind of problem
(sound analisys). I take a look at JTAPI but i don't have any
telephone in this context, i just have to analyze a normal sound
signal from the sound card. I found some applications on the net but
most of them need a modem and don't manage the input from the sound
card, the other are win apps and i cannot configure the actions.

I'm a java programmer so it would be nice if there's a library that i
can use and accept an audio stream in input and give the digit in
output ... if something like that doesn't exists i need at least a
java implementation of a DTMF decoder

thank you for your help

nemo
ne*****@libero.it


what you need is FFT, fast fourier transform which translates sound into an
array of frequencies. i understand that DTMF tones are made up of 7 tones,
each digit is a combination of 3x4 tones (i cant remember off hand what
these frequencies are).

http://www.musicdsp.org/showone.php?id=156

here is some fft analysis code, you will have to get some code to read the
audio to feed it into this algorithm - you should get around 0.9 at the
frequency of your choice.

i know its only a building block but its half the solution to your problem.

dave
Jul 17 '05 #2

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