[asterisk-dev] Support for amr codec?

Nir Simionovich nir.simionovich at gmail.com
Thu Aug 20 04:48:34 CDT 2020


The usage of AMR codecs is mostly in the LTE space - which means that
you're probably aiming to run a slightly higher scale than a single
Asterisk server.
Why not simply install Kamailio+rtpengine as your signalling media
front-end and then relay everything back to Asterisk using a low-footprint
codec, like alaw?

To me, that would sound like the proper solution in this case. Indeed,
there is a minor technical up-hill - but it's worth the effort. Asterisk is
a great codec linguistic,
but when it comes to "pure transcoding" - Kamailio+rtpengine are far more
capable.

On Tue, Aug 18, 2020 at 2:31 PM Carsten Bock <carsten at ng-voice.com> wrote:

> 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.
>
> Thanks,
> Carsten
> --
> 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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