[asterisk-dev] Support for amr codec?

Carsten Bock carsten at ng-voice.com
Tue Aug 18 06:30:53 CDT 2020

The comfort noise topic was not an issue, until someone got a Samsung S20
in one of our VoLTE deployments.... ;-)
There are different types of comfort noise in AMR/AMR-WB and only newer
phones use the full scale of comfort noise there is.

Carsten Bock I CTO & Founder

ng-voice GmbH

Trostbr├╝cke 1 I 20457 Hamburg I Germany
T +49 40 524 75 93-40 | M +49 179 2021244 I www.ng-voice.com

Registry Office at Local Court Hamburg, HRB 120189
Managing Directors: Dr. David Bachmann, Carsten Bock

Am Di., 18. Aug. 2020 um 11:48 Uhr schrieb Michael Maier <
m1278468 at mailbox.org>:

> On 18.08.20 at 10:49 Carsten Bock wrote:
> > Hi,
> >
> > one of the big issues with AMR/AMR-WB and Asterisk is that usually
> devices
> > speaking AMR/AMR-WB do use quite a lot of comfort noise, which is not
> > supported by Asterisk as far as I know. Even if you use the patch from
> the
> > above link, you might end up with some distorted noise.
> Well, during my tests I in fact noticed some more or less silent
> distortions which may be caused by comfort noise generated by the mobile(?)
> (it's only from mobile -> local phone -
> not vice versa). For me it sounds like a pretty silent steam engine.
> I tested with amr and amr-wb in conjunction with transcoding (as I'm
> having no local phone supporting amr. Transcoding was between g722 or
> g711). Therefore I can't say for sure if
> this distortion is a result of transcoding or not. I could here it with
> two different mobiles (iPhone and Huawei). After muting of the iPhone, the
> distortion mostly went away (no
> change with the Huawei mobile).
> Thanks
> Michael
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