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DTMF detection on a GSM AMR bitstream

Started by e_voice61 June 29, 2003
Hi all,

Do anyone know of a way to detect DTMF on a GSM AMR bitstream without
fully decoding it?
I will be happy to know if you can do it on ITU-T voice codecs as
well (G.723.1, G.728, G.729).

Thanks



On Sun, Jun 29, 2003 at 07:19:02AM -0000, e_voice61 wrote:
> Hi all,
>
> Do anyone know of a way to detect DTMF on a GSM AMR bitstream without
> fully decoding it?
> I will be happy to know if you can do it on ITU-T voice codecs as
> well (G.723.1, G.728, G.729).
>

These codecs are optimized for voice. They are not able to carry DTMF
tones reliably. So even with a full decode, you won't be able to
detect them.

They have to be transmitted out-of-band.
--
Nicolas Bougues
Axialys Interactive


G.728 will pass DTMF tones with perfect results as theory predicts and both lab
and field testing have validated. The same is true for at least Annex E of
G.729.

And as you said, G.723.1 will unfortunately not pass DTMF at either rate. Chuck

In a message dated 6/29/2003 2:52:06 PM Eastern Standard Time,
writes:

>
>
> On Sun, Jun 29, 2003 at 07:19:02AM -0000, e_voice61 wrote:
> > Hi all,
> >
> > Do anyone know of a way to detect DTMF on a GSM AMR bitstream without
> > fully decoding it?
> > I will be happy to know if you can do it on ITU-T voice codecs as
> > well (G.723.1, G.728, G.729).
> >
>
> These codecs are optimized for voice. They are not able to carry DTMF
> tones reliably. So even with a full decode, you won't be able to
> detect them.
>
> They have to be transmitted out-of-band.
> --
> Nicolas Bougues
> Axialys Interactive >
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