[Freeswitch-users] Removing inband DTMF

[Steven Ayre]

I didn't mean a significant amount of time. 40ms with a ptime of 20ms means
you've already sent a packet containing inbound dtmf.

-Steve



On 16 January 2011 20:54, Chris Rienzo <cmrienzo at gmail.com> wrote:

> 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>
> 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>
>> Avi at amarcus.com> wrote:
>>
>>> <http://wiki.freeswitch.org/wiki/Misc._Dialplan_Tools_start_dtmf>
>>> 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>
>>> 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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