[SIPForum-techwg] Question about annexb=yes or no

[Maulik Shah (maushah)]

Hi Mike
  Annexb=no or yes decides which variant of G.729 codec should be used.
It does not mean disable silence suppression per my knowledge. G.729
Annex B is the default (in absence of annexb value in SDP per RFC3555)
which has inbuilt silence suppression (VAD). Annexb=no implies use G.729
variant which can have silence suppression enabled or disabled as a
separate parameter in the SDP.

Thanks
Maulik  



-----Original Message-----
From: techwg-bounces at sipforum.org [mailto:techwg-bounces at sipforum.org]
On Behalf Of mike xu
Sent: Sunday, May 25, 2008 8:02 PM
To: techwg at sipforum.org
Subject: [SIPForum-techwg] Question about annexb=yes or no

Hi all,

In RFC3555 section 4.1.9, it said "annexb: indicates that Annex B,
voice activity detection, is        used or preferred". Could somebody
explain this in more details?
Take an example, if
annexb=no
was received, does it mean that I should disable local side's silence
suppression (didn't send silence suppression frames)?

And if I send annexb=no in my INVITE's SDP, it means that my local
side's silence suppression was disabled and the callee should not send
silence suppression frames to me?

Thanks in advance,
Mike
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