[asterisk-users] iLBC codec

[Tilghman Lesher]

On Thursday 04 September 2008 05:55:48 Nhadie wrote:
> Hi,
>
> I am trying to test the ilbc codec on asterisk.
>
> allow=ilbc
> disallow=all
>
> using zoiper on two extensions, i set codec on zoiper to ilbc and
> disabled other codecs
>
> tested a call, looked at the channel:
>
>    NativeFormats: 0x400 (ilbc)
>      WriteFormat: 0x40 (slin)
>       ReadFormat: 0x40 (slin)
>   WriteTranscode: Yes
>    ReadTranscode: Yes
>
> based on that it looks like it's transcoding  between ilbc and slin.
> isn't it supposed to use ilbc and not do transcoding?

If you're doing anything at all that requires Asterisk to uncompress the
audio (recording, mixing, conferencing, spying, etc.), then that would be the
reason.  You cannot directly mix a compressed codec; you have to decompress
the stream first.  Similarly, if you're recording, for example, a wav file,
one of the steps in recording that wav file is to decompress the audio stream.

-- 
Tilghman