[Freeswitch-users] Removing inband DTMF

[Christopher Rienzo]

Yes, that's true.  I usually see 10-30ms of dtmf followed by RFC2833
packets.


On Sun, Jan 16, 2011 at 4:47 PM, Steven Ayre <steveayre at gmail.com> wrote:

> 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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