On 2/22/07, [EMAIL PROTECTED]
<[EMAIL PROTECTED]> wrote:
> Thanks for response.
> Few more doubts.
> if a UA supports G729, G729A, G729B and G729AB. Then is there any way
> the UA can advertise all G729 capabilities in an offer.
> If yes then how will the SDP look like.
>
> Regards
> -venkat
>
>


In the case of g.729A it is not typically advertised at all.  Annex A
is done on the encoding side but the output (media) can be considered
identical between "g.729" and "g.729A".. two endpoints exchanging
g.729 media have no way of knowing whether the other party is using
annex A to generate it.

(I suppose you could technically offer "g.729A" in the range of
dynamic codecs (rtpmap 96--127) but this would not be conventional use
of that range and I wouldn't expect any other devices to send media
based on such an offer).

Note that some ATAs offer "G729A" codec in SDP but this is not correct
and shouldn't be used as a reference (it is a bug/error in default
config of these devices):
http://www.iana.org/assignments/rtp-parameters


Aaron
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