[asterisk-dev] Support for amr codec?

Michael Maier m1278468 at mailbox.org
Tue Aug 18 04:47:48 CDT 2020

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).


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