Programming Interfaces Guide

Finding a Media Format in an SDP Session Structure

sdp_attr_t *sdp_find_media_rtpmap(sdp_media_t *media, const char *format);

The sdp_find_media_rtpmap() function searches the attribute list of the media structure that is specified by the media parameter for the format entry that is specified by the format parameter.

Return Values: The sdp_find_media_rtpmap() function returns a pointer to the format entry (sdp_attr_t *) that is specified by the name parameter when the function completes successfully. In all other cases, the sdp_find_media() function returns a value of NULL.

Example 3–4 Using the sdp_find_media_rtpmap() Function

The incomplete SDP description in this example has two sections, an audio section and a video section.

m=audio 49170 RTP/AVP 0 8
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
m=video 51372 RTP/AVP 31 32
a=rtpmap:31 H261/90000
a=rtpmap:32 MPV/90000

* Assuming that above description is parsed using sdp_parse() and that
* the parsed structure is in "session" sdp_session_t structure.

sdp_media_t     *video;
sdp_attr_t      *mpv;

video = sdp_find_media(session->s_media, "video);
mpv = sdp_find_media_rtpmap(video, "32");

* Now the attribute structure sdp_attr_t, mpv will be having
* values from the attribute field "a=rtpmap:32 MPV/90000"