[asterisk-dev] Opus and VP8

[Lorenzo Miniero]

2013/6/6 Andrea Suisani <sickpig at opinioni.net>

> On 06/06/2013 11:32 AM, Andrea Suisani wrote:
>
>> On 06/06/2013 11:17 AM, Lorenzo Miniero wrote:
>>
>>> core show translation paths opus
>>>
>>
>> I'm in a hurry.
>> just to give you other elements on which speculate further
>>
>> suino*CLI> core show translation paths opus
>> --- Translation paths SRC Codec "opus" sample rate 48000 ---
>>
>                                                      ^^^^^^
>                                                      ^^^^^^
>
> I suddenly realized that for some reason the only enabled sample
> rate is 48 kHz, is it poissible ?
>
>
As I said in other posts, Opus is always advertized as 48kHz, and the
timestamps in RTP always increase as if the rate actually was 48kHz, even
when lower rates (e.g. 16kHz wideband) are actually being used. This is
specified in the Opus RTP draft, and Asterisk is configured accordingly.
The output you see there just means that Asterisk looks at Opus as a 48kHz
codec, so it's normal. The actual sampling rate being used is taken care of
by the codec implementation.

In your case, a opus<->slin48 translation is created, which means that Opus
frames are likely to be exactly, or close to, 48kHz in rate. When a
opus<->8000 translation is created, Opus frames should be narrowband
instead (while, as anticipated, the SDP negotiation and the timestamps
would still refer to a 48kHz sampling rate).

Lorenzo

>
> Andrea
>
>
>
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