[asterisk-dev] DTMF detection in dsp.c intolerant?

Tony Mountifield tony at softins.clara.co.uk
Wed Aug 22 11:09:19 CDT 2007

In article <46CC5424.7030807 at coppice.org>,
Steve Underwood <steveu at coppice.org> wrote:
> Eric "ManxPower" Wieling wrote:
> > Try increasing or decreasing your zaptel rxgain by a couple of Db down 
> > or up.
> >   
> Change the gain - the favourite resort of the desperate. :-)
> This audio is only 6dB below clipping right now.
> [...]
> I actually looked at the audio. Its seriously screwed up. Every digit 
> has two short beeps before it. Its consistent on every digit.

Yes, it's very obviously poor audio, but spandsp still detects the digit
string correctly (kudos!).

So it ought to be possible for Asterisk to do the same, given the same
sequence of samples. I'm just about to go through comparing Asterisk's dsp.c
with spandsp's dtmf.c to look for clues.

Tony Mountifield
Work: tony at softins.co.uk - http://www.softins.co.uk
Play: tony at mountifield.org - http://tony.mountifield.org

More information about the asterisk-dev mailing list