[Freeswitch-users] Removing inband DTMF

[Chris Rienzo]

That's not true.  A detector can spot the start of dtmf in less than 40ms.  The audio frames can then be replaced with 2833 packets.  This is how it works on media gateways.  I'm sure FS could be patched to do this if it uses the spandsp dtmf detector, which can detect dtmf duration.

On Jan 16, 2011, at 11:50, Steven Ayre <steveayre at gmail.com> wrote:

> First of, AFAIK there's nothing in FS that can currently do it.
> 
> I'm not even sure it's possible at all. You can subtract a noise from audio, but the noisy nature of an encoded signal would mean it wouldn't work well (you'd still hear something), and DTMF can't be detected until some of it will have already been sent to the other endpoint so you'd still have the start of each keypress heard.  For the same reason at the end until the detector spots the dtmf has ended you'll still be subtracting from the audio which will actually generate noise. The only way to avoid that may be to introduce a delay but that's not something FS can do.
> 
> -Steve
> 
> 
> 
> On 16 January 2011 15:33, Tamas Jalsovszky <jalsot at gmail.com> wrote:
> Hello,
> 
> Thanks.
> Yeah, I know that command, as far as I know, it is only for detection, it does not change the media.
> Anybody else?
> 
> Regards,
>    T.
> 
> 
> On Fri, Jan 14, 2011 at 11:23 AM, Avi Marcus <Avi at amarcus.com> wrote:
> http://wiki.freeswitch.org/wiki/Misc._Dialplan_Tools_start_dtmf
> start_dtmf does detection from the inband. I'm not sure that it removes them from the rtp, though...
> -Avi
> 
> 
> On Fri, Jan 14, 2011 at 12:14 PM, Tamas Jalsovszky <jalsot at gmail.com> wrote:
> > Hello,
> >
> > Is there a way to remove an inband DTMF signal from the RTP stream with
> > FreeSWITCH?
> > We have a partner with ugly Cirpack which can not remove inband DTMF when
> > the codec is g711. The problem is, that our other party wants RFC2833 only -
> > thus we have to remove inband dtmf. Unfortunately Cirpack is not open to do
> > this.
> >
> > Any advice?
> >
> > Kind regards,
> >    T.
> >
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> 
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