[pjsip] In-band DTMF detection

Archie Rosenblum archie at bbsti.com
Thu Aug 20 08:49:01 EDT 2009


Thank you, David.  I'll take a crack at this at some point ,and if I get it
working, I'll share it with the group.

Take care,
Archie


-----Original Message-----
From: pjsip-bounces at lists.pjsip.org [mailto:pjsip-bounces at lists.pjsip.org]
On Behalf Of David Clark
Sent: Saturday, August 15, 2009 7:18 PM
To: pjsip list; 'pjsip list'
Subject: Re: [pjsip] In-band DTMF detection

Ok I have not done inband but I have done FFT and they are similar in 
terms of approach.  For inband dtmf check out this algorithm.
http://en.wikipedia.org/wiki/Goertzel_algorithm

Now for how to get the audio data from the conference port source to 
the detection algorithm.  Do this.
Just a memory capture device and every time you get a packet of audio 
data call this dedection function to determine what dtmf's are
present, then you can call your on_dtmf_callback function for a 
seemless interface between inband and non-inband calls.

That is the short answer.


At 01:50 PM 8/15/2009, Archie Rosenblum wrote:
>Content-Type: multipart/alternative;
>         boundary="----=_NextPart_000_000B_01CA1DB7.BED967A0"
>Content-Language: en-us
>
>Hi,
>
>Does anyone have an in-band DTMF solution for pjsip?  I know this 
>question has been raised in the past and I am hoping some 
>crackerjack coder has figured it out and would like to share it with 
>the group.  I've been seeing more and more DTMF converted to in-band 
>through various voip providers and I just not savvy enough to 
>understand how to code this detection in pjsip.
>
>Any help is appreciated.
>
>Sincerely,
>Archie
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