Hi,
On Wed, 10 May 2006, Saurav SAHU wrote:
Which sofia-sip tag does the application use to determine the selected
codec as a result of the SOA media negotiation?
you'll have to check the whole SDP. The tags are SOATAG_USER_SDP()
(parsed) and SOATAG_USER_SDP_STR() (raw text). These get you the whole
negotiated local SDP. Then there're SOATAG_REMOTE_SDP*() to get the remote
SDP.
For an example how to use it take a look at sofsip-cli/src/ssc_sip.c
and segments in comments marked with "SDP O/A":
- http://dev-126.openlaboratory.net/repos/sofsip-cli/src/ssc_sip.c
Sofsip-cli takes the _STR versions of local and remote SDP, and passes
these to the media implementation. The media implementation parses the SDP
again (yep, a bit dumb, but I wanted to use ascii SDP in ssc_media.h
interface).
To see how to access the codec information from a parser SDP struct
(sdp_session_t), check for instance
ssc_media_farsight.c:priv_remote_sdp_codecs():
- http://dev-126.openlaboratory.net/repos/sofsip-cli/src/ssc_media_farsight.c
Basicly you can iterate through remote_sdp->sdp_media (media lines) and
for each, sdp_media->m_rtpmaps has the codec information parsed for you
(encoding name, clock rate, channels, params, etc).
If you need to convert from/to ascii and parsed SDP, there are lots of
example both in sofia-sip's sdp documentation, and in sofsip-cli sources.
I am now wondering how to extract the one common codec selected by the
sofia-sip stack so that I establish the media session between the 2 UA
applications.
Hopefully the above helps to get you started. For example sofsip-cli's
implementation for gstreamer is really, really simple. It only supports
one codec, and requires negotiation to a single codec, so if the
negotiation is succesful, you know which codec to use. :)
--
under work: Sofia-SIP at http://sofia-sip.sf.net
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