[Freeswitch-users] Remove inband DTMF on record_session

Moises Silva moises.silva at gmail.com
Mon Jan 21 04:48:16 MSK 2013

On Sun, Jan 20, 2013 at 4:12 PM, Tamas Jalsovszky <jalsot at gmail.com> wrote:

> Hello,
> Is there a way to to remove inbad DTMF from the recorded wav file
> (conditionaly)?
> If not, how could be that done the easyiest way and a way it could get
> into FS git?
> As FS has a great DTMF detector and it has probably all the stuff doing
> such a feature, I think it would be much better than using an external tool
> for removing DTMF from finished wav file - and it would consume more I/O
> probably.
Removing it would not be that hard (ie, inserting silence instead).
Removing it without leaving a trace any DTMF was ever there sounds a tad
more difficult. If you're ok with inserting a silence instead of the tone,
extending the record_session app to detect and remove DTMF is probably what
I'd do.

It is also possible to create a new app that monitors the audio stream and
silence the stream when DTMF is detected, but since the detection takes a
few milliseconds (~50ms), there would be a bit of "bleeding" of DTMF in the
signal, unless the new app also delays the signal by 50ms and then has a
way to strip the DTMF completely.

*Moises Silva
**Manager, Software Engineering***

msilva at sangoma.com

Sangoma Technologies

100 Renfrew Drive, Suite 100, Markham, ON L3R 9R6 Canada

t.   +1 800 388 2475 (N. America)

t.   +1 905 474 1990 x128

f.   +1 905 474 9223


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