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development:sdp-parsing [2011/08/15 12:07] – 109.254.49.8development:sdp-parsing [2012/03/22 12:33] (current) – removed spam 80.250.1.245
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 +<code>
 +/*
 + * by Ovidiu Sas (work in progress)
 + */
 +</code>
 +
 +===== How to use the API =====
 +
 +Here's an example on how to use the API provided by the OpenSER SDP parser:
 +
 +First of all, we need to include the header file:
 +
 +<code>
 +#include "../../parser/sdp/sdp.h"
 +</code>
 +
 +Using the API:
 +
 +<code>
 +/*
 + * This is my method inside a module that handles the given sip message.
 + */
 +void my_method(struct sip_msg* msg)
 +{
 +    sdp_session_cell_t *session;
 +
 +    if (msg == NULL) {
 +        LM_ERR("null msg\n");
 +        return;
 +    }
 +
 +    /* Check for SDP. */
 +    if (0 == parse_sdp(msg)) {
 +        LM_DBG("we have SDP!\n");
 +        /* Let's print the content of SDP via a DBG log.
 +         * Check openser logs to see the output.
 +         */
 +
 +        /* initializing pointer to the first session
 +         * and start iterating through sessions.
 +         */
 +        session = msg->sdp->sessions;
 +        while (session) {
 +            print_sdp_session(session);
 +            session = session->next;
 +        }
 +    }
 +}
 +</code>
 +
 +
 +===== How to decipher the SDP =====
 +
 +Here's an example of a parsed SDP:
 +
 +<code>
 +Content-Type: multipart / mixed;boundary=unique-boundary-1
 +Content-Length:  346
 +
 +Content-Type: application/SDP.
 +Content-Disposition: session
 +
 +v=0
 +o=user1 53655765 2353687637 IN IP4 10.11.10.148
 +s=-
 +c=IN IP4 10.11.10.148
 +t=0 0
 +m=audio 6002 RTP/AVP 0 1 18
 +a=rtpmap:0 PCMU/8000
 +a=inactive
 +
 +--unique-boundary-1
 +--unique-boundary-1
 +Content-Type: application/text
 +
 +Hello
 +
 +--unique-boundary-1--
 +</code>
 +
 +And now the parsed structure.
 +
 +Here are the debug logs:
 +<code>
 +DBG:core:print_sdp_session: ..session[0]:0x8174e50=>(nil) 'session' (1)=>0x8174e70
 +DBG:core:print_sdp_session: ....stream[0]:0x8174e70=>(nil) {0x817ce18} 'audio' '6002' 'RTP/AVP' '0 1 18' (3)=>0x817cdd8
 +DBG:core:print_sdp_session: ......payload[2]:0x817cdd8=>0x8174ef8 p_payload_attr[2]:0x817cdd8 '18' '' '' '' '' ''
 +DBG:core:print_sdp_session: ......payload[1]:0x8174ef8=>0x8174eb8 p_payload_attr[1]:0x8174ef8 '1' '' '' '' '' ''
 +DBG:core:print_sdp_session: ......payload[0]:0x8174eb8=>(nil) p_payload_attr[0]:0x8174eb8 '0' 'PCMU' '8000' '' 'inactive' ''
 +</code>
 +
 +And how to decipher them:
 +We have one session.  The session has one stream.  The stream has three payloads:
 +* [b]session[0][/b] with the Content-Disposition header set to "[b]session[/b]".
 +** [b]stream[0][/b] identified by the "[b]m=[/b]" line with the following parameters:
 +*** type: [b]audio[/b]
 +*** port: [b]6002[/b]
 +*** transport: [b]RTP/AVP[/b]
 +*** payloads: [b]0 1 18[/b]
 +**** [b]payload[0][/b] identified by id "[b]0[/b]" with the following attributes:
 +***** codec name: [b]PCMU[/b]
 +***** sample rate: [b]8000[/b]
 +***** attribute: [b]inactive[/b]
 +**** [b]payload[1][/b] identified by id "[b]1[/b]" with the following attributes:
 +**** [b]payload[2][/b]identified by id "[b]18[/b]" with the following attributes:
  

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