[asterisk-dev] Opus and VP8

Andrea Suisani sickpig at opinioni.net
Thu Jun 6 10:13:29 CDT 2013


On 06/06/2013 05:03 PM, Andrea Suisani wrote:
>
>> 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.
>
> check
>
>> 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.
>
> got it
>
>> 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).
>
> so as you stated in a prev email the Opus codec implementation should
> automatically switch to a 8 kHz sample rate once it realize that the peer
> is using a codec that works with a 8 kHz sampling rate (e.g. GSM/ulaw/g729)
>
> his auto-adjustment seems to not work correctly in my env.
^^^^

typo, I menat "this"

Andrea



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