Closed #1692: Allow multiple codecs in SDP answer

By default, the setting is disabled, to change it during run-time, use the function pjmedia_sdp_neg_set_allow_multiple_codecs().



git-svn-id: http://svn.pjsip.org/repos/pjproject/trunk@4577 74dad513-b988-da41-8d7b-12977e46ad98

3 files changed, 54 insertions, 5 deletions

diff --git a/pjmedia/include/pjmedia/config.h b/pjmedia/include/pjmedia/config.h
index d718b659..9eec63e8 100644
--- a/pjmedia/include/pjmedia/config.h
+++ b/pjmedia/include/pjmedia/config.h
@@ -668,6 +668,19 @@
 #   define PJMEDIA_SDP_NEG_PREFER_REMOTE_CODEC_ORDER	1
 #endif
 
+/**
+ * This specifies the behavior of the SDP negotiator when responding to an
+ * offer, whether it should answer with multiple formats or not.
+ *
+ * Note that this behavior can be changed during run-time by calling
+ * pjmedia_sdp_neg_set_allow_multiple_codecs().
+ *
+ * Default is 0 (to maintain backward compatibility)
+ */
+#ifndef PJMEDIA_SDP_NEG_ANSWER_MULTIPLE_CODECS
+#   define PJMEDIA_SDP_NEG_ANSWER_MULTIPLE_CODECS	0
+#endif
+
 
 /**
  * This specifies the maximum number of the customized SDP format
diff --git a/pjmedia/include/pjmedia/sdp_neg.h b/pjmedia/include/pjmedia/sdp_neg.h
index 3f6eb319..a17c74ce 100644
--- a/pjmedia/include/pjmedia/sdp_neg.h
+++ b/pjmedia/include/pjmedia/sdp_neg.h
@@ -416,6 +416,23 @@ PJ_DECL(pj_status_t)
 pjmedia_sdp_neg_set_prefer_remote_codec_order(pjmedia_sdp_neg *neg,
 					      pj_bool_t prefer_remote);
 
+/**
+ * This specifies the behavior of the SDP negotiator when responding to an
+ * offer, whether it should answer with multiple formats or not.
+ *
+ * By default, the value in PJMEDIA_SDP_NEG_ANSWER_MULTIPLE_CODECS will
+ * be used.
+ *
+ * @param neg           The SDP negotiator instance.
+ * @param answer_multiple
+ *                      If non-zero, the negotiator will respond with
+ *                      multiple formats. If zero only a single format
+ *                      will be returned.
+ */
+PJ_DECL(pj_status_t)
+pjmedia_sdp_neg_set_answer_multiple_codecs(pjmedia_sdp_neg *neg,
+                                           pj_bool_t answer_multiple);
+
 
 /**
  * Get SDP negotiator state.
diff --git a/pjmedia/src/pjmedia/sdp_neg.c b/pjmedia/src/pjmedia/sdp_neg.c
index 160a082e..ebed3a36 100644
--- a/pjmedia/src/pjmedia/sdp_neg.c
+++ b/pjmedia/src/pjmedia/sdp_neg.c
@@ -33,6 +33,7 @@ struct pjmedia_sdp_neg
 {
     pjmedia_sdp_neg_state state;	    /**< Negotiator state.	     */
     pj_bool_t		  prefer_remote_codec_order;
+    pj_bool_t             answer_with_multiple_codecs;
     pj_bool_t		  has_remote_answer;
     pj_bool_t		  answer_was_remote;
 
@@ -114,6 +115,7 @@ PJ_DEF(pj_status_t) pjmedia_sdp_neg_create_w_local_offer( pj_pool_t *pool,
 
     neg->state = PJMEDIA_SDP_NEG_STATE_LOCAL_OFFER;
     neg->prefer_remote_codec_order = PJMEDIA_SDP_NEG_PREFER_REMOTE_CODEC_ORDER;
+    neg->answer_with_multiple_codecs = PJMEDIA_SDP_NEG_ANSWER_MULTIPLE_CODECS;
     neg->initial_sdp = pjmedia_sdp_session_clone(pool, local);
     neg->neg_local_sdp = pjmedia_sdp_session_clone(pool, local);
 
@@ -183,6 +185,19 @@ PJ_DEF(pj_status_t) pjmedia_sdp_neg_set_prefer_remote_codec_order(
 
 
 /*
+ * Set multiple codec answering.
+ */
+PJ_DEF(pj_status_t) pjmedia_sdp_neg_set_answer_multiple_codecs(
+                        pjmedia_sdp_neg *neg,
+                        pj_bool_t answer_multiple)
+{
+    PJ_ASSERT_RETURN(neg, PJ_EINVAL);
+    neg->answer_with_multiple_codecs = answer_multiple;
+    return PJ_SUCCESS;
+}
+
+
+/*
  * Get SDP negotiator state.
  */
 PJ_DEF(pjmedia_sdp_neg_state) pjmedia_sdp_neg_get_state( pjmedia_sdp_neg *neg )
@@ -1010,6 +1025,7 @@ static void apply_answer_symmetric_pt(pj_pool_t *pool,
 /* Try to match offer with answer. */
 static pj_status_t match_offer(pj_pool_t *pool,
 			       pj_bool_t prefer_remote_codec_order,
+                               pj_bool_t answer_with_multiple_codecs,
 			       const pjmedia_sdp_media *offer,
 			       const pjmedia_sdp_media *preanswer,
 			       const pjmedia_sdp_session *preanswer_sdp,
@@ -1075,11 +1091,11 @@ static pj_status_t match_offer(pj_pool_t *pool,
 
 		master_has_codec = 1;
 
-		/* We just need to select one codec. 
+		/* We just need to select one codec if not allowing multiple.
 		 * Continue if we have selected matching codec for previous 
 		 * payload.
 		 */
-		if (found_matching_codec)
+		if (!answer_with_multiple_codecs && found_matching_codec)
 		    continue;
 
 		/* Find matching codec in local descriptor. */
@@ -1119,7 +1135,7 @@ static pj_status_t match_offer(pj_pool_t *pool,
 		    is_codec = 0;
 		} else {
 		    master_has_codec = 1;
-		    if (found_matching_codec)
+		    if (!answer_with_multiple_codecs && found_matching_codec)
 			continue;
 		    is_codec = 1;
 		}
@@ -1277,6 +1293,7 @@ static pj_status_t match_offer(pj_pool_t *pool,
 /* Create complete answer for remote's offer. */
 static pj_status_t create_answer( pj_pool_t *pool,
 				  pj_bool_t prefer_remote_codec_order,
+                                  pj_bool_t answer_with_multiple_codecs,
 				  const pjmedia_sdp_session *initial,
 				  const pjmedia_sdp_session *offer,
 				  pjmedia_sdp_session **p_answer)
@@ -1326,7 +1343,8 @@ static pj_status_t create_answer( pj_pool_t *pool,
                 pj_status_t status2;
 
 		/* See if it has matching codec. */
-		status2 = match_offer(pool, prefer_remote_codec_order, 
+		status2 = match_offer(pool, prefer_remote_codec_order,
+                                      answer_with_multiple_codecs,
 				      om, im, initial, &am);
 		if (status2 == PJ_SUCCESS) {
 		    /* Mark media as used. */
@@ -1424,7 +1442,8 @@ PJ_DEF(pj_status_t) pjmedia_sdp_neg_negotiate( pj_pool_t *pool,
     } else {
 	pjmedia_sdp_session *answer = NULL;
 
-	status = create_answer(pool, neg->prefer_remote_codec_order, 
+	status = create_answer(pool, neg->prefer_remote_codec_order,
+                               neg->answer_with_multiple_codecs,
 			       neg->neg_local_sdp, neg->neg_remote_sdp,
 			       &answer);
 	if (status == PJ_SUCCESS) {