Iñaki Baz Castillo schrieb:
> 2009/2/25 Klaus Darilion <[email protected]>:
>> I think if Alice announces G711 and G729, and Bob answers with G.729,
>> Alice must send with G729 and Bob can send with G711 too. Is this correct?
> 
> If Bob answers G729 then Alice expects that Bob will send G729.

I wonder why? If I offer somebody to talk to me in English or German, I 
have to be prepared to receive English or German, even if I started 
talking in German.

Thus from a logical point of view, all the offered codecs should be 
supported. If the device supports only a single on at the time, it can 
send reINVITE with a single offer to lock down on a single codec.


> But if Bob sends G711, how will detect Alice that the incoming RTP is not 
> G729?

There is the payloadtype field in the RTP header. So it is easy to 
differ them.

klaus


> The negoziation is supposed to have place during the SDP exchange and
> it must be deterministic, am I wrong?
> 
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