Re: i4l dtmf errors

From: Wolfgang Fritz (
Date: Sat Dec 14 2002 - 15:51:10 EST

Roy Sigurd Karlsbakk wrote:

> hi
> it seems isdn4linux detects DTMF tones from normal speach. This is
> rather annoying when using i4l for voice with This is
> tested on all recent kernels

The DTMF detection is broken since kernel 2.0.x. I have a patch for a
2.2 kernel which may manually be applied 2.4 kernels with some manual
work. It fixes an overflow problem in the goertzel algorithm (which
does the basic tone detection) and changes the algorithm to detect the
DTMF pairs. If interested, I can try to recover that patch.

> see thread "[MGCP] Asterisk/D-Link phones generates ugly DTMF
> tones!!!" at for more info.
> roy

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