Merge changes from topic 'sdp_api_adjustments'

* changes:
  SDP: Make process possible multiple fmtp attributes per rtpmap.
  SDP: Explicitly stop a RTP instance before destoying it.
  SDP: Rework merge_capabilities().
  SDP: Update ast_get_topology_from_sdp() to keep RTP map.

include/asterisk/sdp.h

@@ -561,7 +561,40 @@ struct ast_sdp *ast_sdp_alloc(struct ast_sdp_o_line *o_line,
 	struct ast_sdp_t_line *t_line);
 
 /*!
- * \brief Find an attribute on the top-level SDP
+ * \brief Find the first attribute match index in the top-level SDP
+ *
+ * \note This will not search within streams for the given attribute.
+ *
+ * \param sdp The SDP in which to search
+ * \param attr_name The name of the attribute to search for
+ * \param payload Optional payload number to search for. If irrelevant, set to -1
+ *
+ * \retval index of attribute line on success.
+ * \retval -1 on failure or not found.
+ *
+ * \since 15.0.0
+ */
+int ast_sdp_find_a_first(const struct ast_sdp *sdp, const char *attr_name, int payload);
+
+/*!
+ * \brief Find the next attribute match index in the top-level SDP
+ *
+ * \note This will not search within streams for the given attribute.
+ *
+ * \param sdp The SDP in which to search
+ * \param last The last matching index found
+ * \param attr_name The name of the attribute to search for
+ * \param payload Optional payload number to search for. If irrelevant, set to -1
+ *
+ * \retval index of attribute line on success.
+ * \retval -1 on failure or not found.
+ *
+ * \since 15.0.0
+ */
+int ast_sdp_find_a_next(const struct ast_sdp *sdp, int last, const char *attr_name, int payload);
+
+/*!
+ * \brief Find an attribute in the top-level SDP
  *
  * \note This will not search within streams for the given attribute.
  *
@@ -578,9 +611,40 @@ struct ast_sdp_a_line *ast_sdp_find_attribute(const struct ast_sdp *sdp,
 	const char *attr_name, int payload);
 
 /*!
- * \brief Find an attribute on an SDP stream (m-line)
+ * \brief Find the first attribute match index in an SDP stream (m-line)
  *
- * \param sdp The SDP in which to search
+ * \param m_line The SDP m-line in which to search
+ * \param attr_name The name of the attribute to search for
+ * \param payload Optional payload number to search for. If irrelevant, set to -1
+ *
+ * \retval index of attribute line on success.
+ * \retval -1 on failure or not found.
+ *
+ * \since 15.0.0
+ */
+int ast_sdp_m_find_a_first(const struct ast_sdp_m_line *m_line, const char *attr_name,
+	int payload);
+
+/*!
+ * \brief Find the next attribute match index in an SDP stream (m-line)
+ *
+ * \param m_line The SDP m-line in which to search
+ * \param last The last matching index found
+ * \param attr_name The name of the attribute to search for
+ * \param payload Optional payload number to search for. If irrelevant, set to -1
+ *
+ * \retval index of attribute line on success.
+ * \retval -1 on failure or not found.
+ *
+ * \since 15.0.0
+ */
+int ast_sdp_m_find_a_next(const struct ast_sdp_m_line *m_line, int last,
+	const char *attr_name, int payload);
+
+/*!
+ * \brief Find an attribute in an SDP stream (m-line)
+ *
+ * \param m_line The SDP m-line in which to search
  * \param attr_name The name of the attribute to search for
  * \param payload Optional payload number to search for. If irrelevant, set to -1
  *
@@ -638,11 +702,12 @@ void ast_sdp_rtpmap_free(struct ast_sdp_rtpmap *rtpmap);
  * each m-line corresponding to a stream in the created topology.
  *
  * \param sdp The SDP to convert
+ * \param g726_non_standard Non-zero if G.726 is non-standard
  *
  * \retval NULL An error occurred when converting
  * \retval non-NULL The generated stream topology
  *
  * \since 15.0.0
  */
-struct ast_stream_topology *ast_get_topology_from_sdp(const struct ast_sdp *sdp);
+struct ast_stream_topology *ast_get_topology_from_sdp(const struct ast_sdp *sdp, int g726_non_standard);
 #endif /* _SDP_PRIV_H */

include/asterisk/stream.h

@@ -55,39 +55,39 @@ typedef void (*ast_stream_data_free_fn)(void *);
  * \brief States that a stream may be in
  */
 enum ast_stream_state {
-    /*!
-     * \brief Set when the stream has been removed
-     */
-    AST_STREAM_STATE_REMOVED = 0,
-    /*!
-     * \brief Set when the stream is sending and receiving media
-     */
-    AST_STREAM_STATE_SENDRECV,
-    /*!
-     * \brief Set when the stream is sending media only
-     */
-    AST_STREAM_STATE_SENDONLY,
-    /*!
-     * \brief Set when the stream is receiving media only
-     */
-    AST_STREAM_STATE_RECVONLY,
-    /*!
-     * \brief Set when the stream is not sending OR receiving media
-     */
-    AST_STREAM_STATE_INACTIVE,
+	/*!
+	 * \brief Set when the stream has been removed/declined
+	 */
+	AST_STREAM_STATE_REMOVED = 0,
+	/*!
+	 * \brief Set when the stream is sending and receiving media
+	 */
+	AST_STREAM_STATE_SENDRECV,
+	/*!
+	 * \brief Set when the stream is sending media only
+	 */
+	AST_STREAM_STATE_SENDONLY,
+	/*!
+	 * \brief Set when the stream is receiving media only
+	 */
+	AST_STREAM_STATE_RECVONLY,
+	/*!
+	 * \brief Set when the stream is not sending OR receiving media
+	 */
+	AST_STREAM_STATE_INACTIVE,
 };
 
 /*!
  * \brief Stream data slots
  */
 enum ast_stream_data_slot {
-    /*!
-     * \brief Data slot for RTP instance
-     */
-	AST_STREAM_DATA_RTP_INSTANCE = 0,
-    /*!
-     * \brief Controls the size of the data pointer array
-     */
+	/*!
+	 * \brief Data slot for RTP instance
+	 */
+	AST_STREAM_DATA_RTP_CODECS = 0,
+	/*!
+	 * \brief Controls the size of the data pointer array
+	 */
 	AST_STREAM_DATA_SLOT_MAX
 };
 
@@ -386,15 +386,15 @@ struct ast_stream_topology *ast_stream_topology_create_from_format_cap(
  *
  * \param topology The topology of streams
  *
-  * \retval non-NULL success
-  * \retval NULL failure
-  *
-  * \note The stream topology is NOT altered by this function.
-  *
-  * \since 15
-  */
+ * \retval non-NULL success
+ * \retval NULL failure
+ *
+ * \note The stream topology is NOT altered by this function.
+ *
+ * \since 15
+ */
 struct ast_format_cap *ast_format_cap_from_stream_topology(
-    struct ast_stream_topology *topology);
+	struct ast_stream_topology *topology);
 
 /*!
  * \brief Gets the first stream of a specific type from the topology

main/sdp.c

@@ -508,44 +508,81 @@ int ast_sdp_m_add_format(struct ast_sdp_m_line *m_line, const struct ast_sdp_opt
 		|| sdp_m_add_fmtp(m_line, format, rtp_code) ? -1 : 0;
 }
 
-static struct ast_sdp_a_line *sdp_find_attribute_common(const struct ast_sdp_a_lines *a_lines,
+static int sdp_find_a_common(const struct ast_sdp_a_lines *a_lines, int start,
 	const char *attr_name, int payload)
 {
 	struct ast_sdp_a_line *a_line;
-	int i;
+	int idx;
+
+	ast_assert(-1 <= start);
 
-	for (i = 0; i < AST_VECTOR_SIZE(a_lines); ++i) {
+	for (idx = start + 1; idx < AST_VECTOR_SIZE(a_lines); ++idx) {
 		int a_line_payload;
 
-		a_line = AST_VECTOR_GET(a_lines, i);
+		a_line = AST_VECTOR_GET(a_lines, idx);
 		if (strcmp(a_line->name, attr_name)) {
 			continue;
 		}
 
 		if (payload >= 0) {
 			int sscanf_res;
+
 			sscanf_res = sscanf(a_line->value, "%30d", &a_line_payload);
 			if (sscanf_res == 1 && payload == a_line_payload) {
-				return a_line;
+				return idx;
 			}
 		} else {
-			return a_line;
+			return idx;
 		}
 	}
 
-	return NULL;
+	return -1;
+}
+
+int ast_sdp_find_a_first(const struct ast_sdp *sdp, const char *attr_name, int payload)
+{
+	return sdp_find_a_common(sdp->a_lines, -1, attr_name, payload);
+}
+
+int ast_sdp_find_a_next(const struct ast_sdp *sdp, int last, const char *attr_name, int payload)
+{
+	return sdp_find_a_common(sdp->a_lines, last, attr_name, payload);
 }
 
 struct ast_sdp_a_line *ast_sdp_find_attribute(const struct ast_sdp *sdp,
 	const char *attr_name, int payload)
 {
-	return sdp_find_attribute_common(sdp->a_lines, attr_name, payload);
+	int idx;
+
+	idx = ast_sdp_find_a_first(sdp, attr_name, payload);
+	if (idx < 0) {
+		return NULL;
+	}
+	return ast_sdp_get_a(sdp, idx);
+}
+
+int ast_sdp_m_find_a_first(const struct ast_sdp_m_line *m_line, const char *attr_name,
+	int payload)
+{
+	return sdp_find_a_common(m_line->a_lines, -1, attr_name, payload);
+}
+
+int ast_sdp_m_find_a_next(const struct ast_sdp_m_line *m_line, int last,
+	const char *attr_name, int payload)
+{
+	return sdp_find_a_common(m_line->a_lines, last, attr_name, payload);
 }
 
 struct ast_sdp_a_line *ast_sdp_m_find_attribute(const struct ast_sdp_m_line *m_line,
 	const char *attr_name, int payload)
 {
-	return sdp_find_attribute_common(m_line->a_lines, attr_name, payload);
+	int idx;
+
+	idx = ast_sdp_m_find_a_first(m_line, attr_name, payload);
+	if (idx < 0) {
+		return NULL;
+	}
+	return ast_sdp_m_get_a(m_line, idx);
 }
 
 struct ast_sdp_rtpmap *ast_sdp_rtpmap_alloc(int payload, const char *encoding_name,
@@ -644,17 +681,8 @@ static struct ast_sdp_rtpmap *sdp_payload_get_rtpmap(const struct ast_sdp_m_line
 	return ast_sdp_a_get_rtpmap(rtpmap_attr);
 }
 
-/*!
- * \brief Find and process fmtp attributes for a given payload
- *
- * \param m_line The stream on which to search for the fmtp attribute
- * \param payload The specific fmtp attribute to search for
- * \param codecs The current RTP codecs that have been built up
- */
-static void process_fmtp(const struct ast_sdp_m_line *m_line, int payload,
-	struct ast_rtp_codecs *codecs)
+static void process_fmtp_value(const char *value, int payload, struct ast_rtp_codecs *codecs)
 {
-	struct ast_sdp_a_line *attr;
 	char *param;
 	char *param_start;
 	char *param_end;
@@ -662,13 +690,11 @@ static void process_fmtp(const struct ast_sdp_m_line *m_line, int payload,
 	struct ast_format *replace;
 	struct ast_format *format;
 
-	attr = ast_sdp_m_find_attribute(m_line, "fmtp", payload);
-	if (!attr) {
-		return;
-	}
-
-	/* Extract the "a=fmtp:%d %s" attribute parameter string after the payload type. */
-	param_start = ast_skip_nonblanks(attr->value);/* Skip payload type */
+	/*
+	 * Extract the "a=fmtp:%d %s" attribute parameter string value which
+	 * starts after the colon.
+	 */
+	param_start = ast_skip_nonblanks(value);/* Skip payload type */
 	param_start = ast_skip_blanks(param_start);
 	param_end = ast_skip_nonblanks(param_start);
 	if (param_end == param_start) {
@@ -693,6 +719,39 @@ static void process_fmtp(const struct ast_sdp_m_line *m_line, int payload,
 	ao2_ref(format, -1);
 }
 
+/*!
+ * \brief Find and process all fmtp attribute lines for a given payload
+ *
+ * \param m_line The stream on which to search for the fmtp attributes
+ * \param payload The specific fmtp attribute to search for
+ * \param codecs The current RTP codecs that have been built up
+ */
+static void process_fmtp_lines(const struct ast_sdp_m_line *m_line, int payload,
+	struct ast_rtp_codecs *codecs)
+{
+	const struct ast_sdp_a_line *a_line;
+	int idx;
+
+	idx = ast_sdp_m_find_a_first(m_line, "fmtp", payload);
+	for (; 0 <= idx; idx = ast_sdp_m_find_a_next(m_line, idx, "fmtp", payload)) {
+		a_line = ast_sdp_m_get_a(m_line, idx);
+		ast_assert(a_line != NULL);
+
+		process_fmtp_value(a_line->value, payload, codecs);
+	}
+}
+
+/*
+ * Needed so we don't have an external function referenced as data.
+ * The dynamic linker doesn't handle that very well.
+ */
+static void rtp_codecs_free(struct ast_rtp_codecs *codecs)
+{
+	if (codecs) {
+		ast_rtp_codecs_payloads_destroy(codecs);
+	}
+}
+
 /*!
  * \brief Convert an SDP stream into an Asterisk stream
  *
@@ -700,16 +759,19 @@ static void process_fmtp(const struct ast_sdp_m_line *m_line, int payload,
  * This takes formats, as well as clock-rate and fmtp attributes into account.
  *
  * \param m_line The SDP media section to convert
+ * \param g726_non_standard Non-zero if G.726 is non-standard
+ *
  * \retval NULL An error occurred
  * \retval non-NULL The converted stream
  */
-static struct ast_stream *get_stream_from_m(const struct ast_sdp_m_line *m_line)
+static struct ast_stream *get_stream_from_m(const struct ast_sdp_m_line *m_line, int g726_non_standard)
 {
 	int i;
 	int non_ast_fmts;
-	struct ast_rtp_codecs codecs;
+	struct ast_rtp_codecs *codecs;
 	struct ast_format_cap *caps;
 	struct ast_stream *stream;
+	enum ast_rtp_options options;
 
 	caps = ast_format_cap_alloc(AST_FORMAT_CAP_FLAG_DEFAULT);
 	if (!caps) {
@@ -724,8 +786,15 @@ static struct ast_stream *get_stream_from_m(const struct ast_sdp_m_line *m_line)
 	switch (ast_stream_get_type(stream)) {
 	case AST_MEDIA_TYPE_AUDIO:
 	case AST_MEDIA_TYPE_VIDEO:
-		ast_rtp_codecs_payloads_initialize(&codecs);
+		codecs = ast_calloc(1, sizeof(*codecs));
+		if (!codecs || ast_rtp_codecs_payloads_initialize(codecs)) {
+			rtp_codecs_free(codecs);
+			ast_stream_free(stream);
+			ao2_ref(caps, -1);
+			return NULL;
+		}
 
+		options = g726_non_standard ? AST_RTP_OPT_G726_NONSTANDARD : 0;
 		for (i = 0; i < ast_sdp_m_get_payload_count(m_line); ++i) {
 			struct ast_sdp_payload *payload_s;
 			struct ast_sdp_rtpmap *rtpmap;
@@ -733,22 +802,25 @@ static struct ast_stream *get_stream_from_m(const struct ast_sdp_m_line *m_line)
 
 			payload_s = ast_sdp_m_get_payload(m_line, i);
 			sscanf(payload_s->fmt, "%30d", &payload);
-			ast_rtp_codecs_payloads_set_m_type(&codecs, NULL, payload);
 
 			rtpmap = sdp_payload_get_rtpmap(m_line, payload);
 			if (!rtpmap) {
+				/* No rtpmap attribute.  Try static payload type format assignment */
+				ast_rtp_codecs_payloads_set_m_type(codecs, NULL, payload);
 				continue;
 			}
-			ast_rtp_codecs_payloads_set_rtpmap_type_rate(&codecs, NULL,
-				payload, m_line->type, rtpmap->encoding_name, 0,
-				rtpmap->clock_rate);
-			ast_sdp_rtpmap_free(rtpmap);
 
-			process_fmtp(m_line, payload, &codecs);
+			if (!ast_rtp_codecs_payloads_set_rtpmap_type_rate(codecs, NULL, payload,
+				m_line->type, rtpmap->encoding_name, options, rtpmap->clock_rate)) {
+				/* Successfully mapped the payload type to format */
+				process_fmtp_lines(m_line, payload, codecs);
+			}
+			ast_sdp_rtpmap_free(rtpmap);
 		}
 
-		ast_rtp_codecs_payload_formats(&codecs, caps, &non_ast_fmts);
-		ast_rtp_codecs_payloads_destroy(&codecs);
+		ast_rtp_codecs_payload_formats(codecs, caps, &non_ast_fmts);
+		ast_stream_set_data(stream, AST_STREAM_DATA_RTP_CODECS, codecs,
+			(ast_stream_data_free_fn) rtp_codecs_free);
 		break;
 	case AST_MEDIA_TYPE_IMAGE:
 		for (i = 0; i < ast_sdp_m_get_payload_count(m_line); ++i) {
@@ -773,7 +845,7 @@ static struct ast_stream *get_stream_from_m(const struct ast_sdp_m_line *m_line)
 	return stream;
 }
 
-struct ast_stream_topology *ast_get_topology_from_sdp(const struct ast_sdp *sdp)
+struct ast_stream_topology *ast_get_topology_from_sdp(const struct ast_sdp *sdp, int g726_non_standard)
 {
 	struct ast_stream_topology *topology;
 	int i;
@@ -786,11 +858,21 @@ struct ast_stream_topology *ast_get_topology_from_sdp(const struct ast_sdp *sdp)
 	for (i = 0; i < ast_sdp_get_m_count(sdp); ++i) {
 		struct ast_stream *stream;
 
-		stream = get_stream_from_m(ast_sdp_get_m(sdp, i));
+		stream = get_stream_from_m(ast_sdp_get_m(sdp, i), g726_non_standard);
 		if (!stream) {
-			continue;
+			/*
+			 * The topology cannot match the SDP because
+			 * we failed to create a corresponding stream.
+			 */
+			ast_stream_topology_free(topology);
+			return NULL;
+		}
+		if (ast_stream_topology_append_stream(topology, stream) < 0) {
+			/* Failed to add stream to topology */
+			ast_stream_free(stream);
+			ast_stream_topology_free(topology);
+			return NULL;
 		}
-		ast_stream_topology_append_stream(topology, stream);
 	}
 
 	return topology;

main/sdp_state.c

@@ -64,6 +64,11 @@ enum ast_sdp_role {
 
 typedef int (*state_fn)(struct ast_sdp_state *state);
 
+struct sdp_state_rtp {
+	/*! The underlying RTP instance */
+	struct ast_rtp_instance *instance;
+};
+
 struct sdp_state_udptl {
 	/*! The underlying UDPTL instance */
 	struct ast_udptl *instance;
@@ -74,7 +79,7 @@ struct sdp_state_stream {
 	enum ast_media_type type;
 	union {
 		/*! The underlying RTP instance */
-		struct ast_rtp_instance *instance;
+		struct sdp_state_rtp *rtp;
 		/*! The underlying UDPTL instance */
 		struct sdp_state_udptl *udptl;
 	};
@@ -86,6 +91,16 @@ struct sdp_state_stream {
 	struct ast_control_t38_parameters t38_local_params;
 };
 
+static void sdp_state_rtp_destroy(void *obj)
+{
+	struct sdp_state_rtp *rtp = obj;
+
+	if (rtp->instance) {
+		ast_rtp_instance_stop(rtp->instance);
+		ast_rtp_instance_destroy(rtp->instance);
+	}
+}
+
 static void sdp_state_udptl_destroy(void *obj)
 {
 	struct sdp_state_udptl *udptl = obj;
@@ -100,9 +115,7 @@ static void sdp_state_stream_free(struct sdp_state_stream *state_stream)
 	switch (state_stream->type) {
 	case AST_MEDIA_TYPE_AUDIO:
 	case AST_MEDIA_TYPE_VIDEO:
-		if (state_stream->instance) {
-			ast_rtp_instance_destroy(state_stream->instance);
-		}
+		ao2_cleanup(state_stream->rtp);
 		break;
 	case AST_MEDIA_TYPE_IMAGE:
 		ao2_cleanup(state_stream->udptl);
@@ -145,10 +158,10 @@ static void sdp_state_capabilities_free(struct sdp_state_capabilities *capabilit
 static struct ast_sched_context *sched;
 
 /*! \brief Internal function which creates an RTP instance */
-static struct ast_rtp_instance *create_rtp(const struct ast_sdp_options *options,
+static struct sdp_state_rtp *create_rtp(const struct ast_sdp_options *options,
 	enum ast_media_type media_type)
 {
-	struct ast_rtp_instance *rtp;
+	struct sdp_state_rtp *rtp;
 	struct ast_rtp_engine_ice *ice;
 	static struct ast_sockaddr address_rtp;
 	struct ast_sockaddr *media_address = &address_rtp;
@@ -167,38 +180,57 @@ static struct ast_rtp_instance *create_rtp(const struct ast_sdp_options *options
 		}
 	}
 
-	rtp = ast_rtp_instance_new(options->rtp_engine, sched, media_address, NULL);
+	rtp = ao2_alloc_options(sizeof(*rtp), sdp_state_rtp_destroy, AO2_ALLOC_OPT_LOCK_NOLOCK);
 	if (!rtp) {
+		return NULL;
+	}
+
+	rtp->instance = ast_rtp_instance_new(options->rtp_engine, sched, media_address, NULL);
+	if (!rtp->instance) {
 		ast_log(LOG_ERROR, "Unable to create RTP instance using RTP engine '%s'\n",
 			options->rtp_engine);
+		ao2_ref(rtp, -1);
 		return NULL;
 	}
 
-	ast_rtp_instance_set_prop(rtp, AST_RTP_PROPERTY_RTCP, AST_RTP_INSTANCE_RTCP_STANDARD);
-	ast_rtp_instance_set_prop(rtp, AST_RTP_PROPERTY_NAT, options->rtp_symmetric);
+	ast_rtp_instance_set_prop(rtp->instance, AST_RTP_PROPERTY_RTCP,
+		AST_RTP_INSTANCE_RTCP_STANDARD);
+	ast_rtp_instance_set_prop(rtp->instance, AST_RTP_PROPERTY_NAT,
+		options->rtp_symmetric);
 
-	if (options->ice == AST_SDP_ICE_DISABLED && (ice = ast_rtp_instance_get_ice(rtp))) {
-		ice->stop(rtp);
+	if (options->ice == AST_SDP_ICE_DISABLED
+		&& (ice = ast_rtp_instance_get_ice(rtp->instance))) {
+		ice->stop(rtp->instance);
 	}
 
 	if (options->dtmf == AST_SDP_DTMF_RFC_4733 || options->dtmf == AST_SDP_DTMF_AUTO) {
-		ast_rtp_instance_dtmf_mode_set(rtp, AST_RTP_DTMF_MODE_RFC2833);
-		ast_rtp_instance_set_prop(rtp, AST_RTP_PROPERTY_DTMF, 1);
+		ast_rtp_instance_dtmf_mode_set(rtp->instance, AST_RTP_DTMF_MODE_RFC2833);
+		ast_rtp_instance_set_prop(rtp->instance, AST_RTP_PROPERTY_DTMF, 1);
 	} else if (options->dtmf == AST_SDP_DTMF_INBAND) {
-		ast_rtp_instance_dtmf_mode_set(rtp, AST_RTP_DTMF_MODE_INBAND);
+		ast_rtp_instance_dtmf_mode_set(rtp->instance, AST_RTP_DTMF_MODE_INBAND);
 	}
 
-	if (media_type == AST_MEDIA_TYPE_AUDIO &&
-			(options->tos_audio || options->cos_audio)) {
-		ast_rtp_instance_set_qos(rtp, options->tos_audio,
-			options->cos_audio, "SIP RTP Audio");
-	} else if (media_type == AST_MEDIA_TYPE_VIDEO &&
-			(options->tos_video || options->cos_video)) {
-		ast_rtp_instance_set_qos(rtp, options->tos_video,
-			options->cos_video, "SIP RTP Video");
+	switch (media_type) {
+	case AST_MEDIA_TYPE_AUDIO:
+		if (options->tos_audio || options->cos_audio) {
+			ast_rtp_instance_set_qos(rtp->instance, options->tos_audio,
+				options->cos_audio, "SIP RTP Audio");
+		}
+		break;
+	case AST_MEDIA_TYPE_VIDEO:
+		if (options->tos_video || options->cos_video) {
+			ast_rtp_instance_set_qos(rtp->instance, options->tos_video,
+				options->cos_video, "SIP RTP Video");
+		}
+		break;
+	case AST_MEDIA_TYPE_IMAGE:
+	case AST_MEDIA_TYPE_TEXT:
+	case AST_MEDIA_TYPE_UNKNOWN:
+	case AST_MEDIA_TYPE_END:
+		break;
 	}
 
-	ast_rtp_instance_set_last_rx(rtp, time(NULL));
+	ast_rtp_instance_set_last_rx(rtp->instance, time(NULL));
 
 	return rtp;
 }
@@ -278,8 +310,8 @@ static struct sdp_state_capabilities *sdp_initialize_state_capabilities(const st
 		switch (state_stream->type) {
 		case AST_MEDIA_TYPE_AUDIO:
 		case AST_MEDIA_TYPE_VIDEO:
-			state_stream->instance = create_rtp(options, state_stream->type);
-			if (!state_stream->instance) {
+			state_stream->rtp = create_rtp(options, state_stream->type);
+			if (!state_stream->rtp) {
 				sdp_state_stream_free(state_stream);
 				sdp_state_capabilities_free(capabilities);
 				return NULL;
@@ -413,11 +445,11 @@ struct ast_rtp_instance *ast_sdp_state_get_rtp_instance(
 			sdp_state->proposed_capabilities->topology, stream_index)) == AST_MEDIA_TYPE_VIDEO);
 
 	stream_state = sdp_state_get_stream(sdp_state, stream_index);
-	if (!stream_state) {
+	if (!stream_state || !stream_state->rtp) {
 		return NULL;
 	}
 
-	return stream_state->instance;
+	return stream_state->rtp->instance;
 }
 
 struct ast_udptl *ast_sdp_state_get_udptl_instance(
@@ -467,7 +499,7 @@ int ast_sdp_state_get_stream_connection_address(const struct ast_sdp_state *sdp_
 		stream_index))) {
 	case AST_MEDIA_TYPE_AUDIO:
 	case AST_MEDIA_TYPE_VIDEO:
-		ast_rtp_instance_get_local_address(stream_state->instance, address);
+		ast_rtp_instance_get_local_address(stream_state->rtp->instance, address);
 		break;
 	case AST_MEDIA_TYPE_IMAGE:
 		ast_udptl_get_us(stream_state->udptl->instance, address);
@@ -522,6 +554,7 @@ const struct ast_sdp_options *ast_sdp_state_get_options(
  *
  * \param local Our local stream
  * \param remote A remote stream
+ *
  * \retval NULL An error occurred
  * \retval non-NULL The joint stream created
  */
@@ -542,10 +575,6 @@ static struct ast_stream *merge_streams(const struct ast_stream *local,
 		return NULL;
 	}
 
-	if (!local) {
-		return joint_stream;
-	}
-
 	joint_cap = ast_format_cap_alloc(AST_FORMAT_CAP_FLAG_DEFAULT);
 	if (!joint_cap) {
 		ast_stream_free(joint_stream);
@@ -576,63 +605,100 @@ static struct ast_stream *merge_streams(const struct ast_stream *local,
  * \param local The local topology
  * \param media_type The type of stream we are looking for
  * \param[in,out] media_indices Keeps track of where to start searching in the topology
- * \retval NULL No corresponding stream found
- * \retval non-NULL The corresponding stream
+ *
+ * \retval -1 No corresponding stream found
+ * \retval index The corresponding stream index
  */
 static int get_corresponding_index(const struct ast_stream_topology *local,
 	enum ast_media_type media_type, int *media_indices)
 {
 	int i;
-	int winner = -1;
 
 	for (i = media_indices[media_type]; i < ast_stream_topology_get_count(local); ++i) {
 		struct ast_stream *candidate;
 
 		candidate = ast_stream_topology_get_stream(local, i);
 		if (ast_stream_get_type(candidate) == media_type) {
-			winner = i;
-			break;
+			media_indices[media_type] = i + 1;
+			return i;
 		}
 	}
 
-	media_indices[media_type] = i + 1;
-	return winner;
+	/* No stream of the type left in the topology */
+	media_indices[media_type] = i;
+	return -1;
 }
 
+/*!
+ * XXX TODO The merge_capabilities() function needs to be split into
+ * merging for new local topologies and new remote topologies.  Also
+ * the possibility of changing the stream types needs consideration.
+ * Audio to video may or may not need us to keep the same RTP instance
+ * because the stream position is still RTP.  A new RTP instance would
+ * cause us to change ports.  Audio to image is definitely going to
+ * happen for T.38.
+ *
+ * A new remote topology as an initial offer needs to dictate the
+ * number of streams and the order.  As a sdp_state option we may
+ * allow creation of new active streams not defined by the current
+ * local topology.  A subsequent remote offer can change the stream
+ * types and add streams.  The sdp_state option could regulate
+ * creation of new active streams here as well.  An answer cannot
+ * change stream types or the number of streams but can decline
+ * streams.  Any attempt to do so should report an error and possibly
+ * disconnect the call.
+ *
+ * A local topology update needs to be merged differently.  It cannot
+ * reduce the number of streams already defined without violating the
+ * SDP RFC.  The local merge could take the new topology stream
+ * verbatim and add declined streams to fill out any shortfall with
+ * the exiting topology.  This strategy is needed if we want to change
+ * an audio stream to an image stream for T.38 fax and vice versa.
+ * The local merge could take the new topology and map the streams to
+ * the existing local topology.  The new topology stream format caps
+ * would be copied into the merged topology so we could change what
+ * codecs are negotiated.
+ */
 /*!
  * \brief Merge existing stream capabilities and a new topology into joint capabilities.
  *
- * This is a bit complicated. The idea is that we already have some capabilities set, and
- * we've now been confronted with a new stream topology. We want to take what's been
- * presented to us and merge those new capabilities with our own.
+ * \param sdp_state The state needing capabilities merged
+ * \param new_topology The new topology to base merged capabilities on
+ * \param is_local If new_topology is a local update.
  *
- * For each of the new streams, we try to find a corresponding stream in our current
- * capabilities. If we find one, then we get the compatible formats of the two streams
- * and create a new stream with those formats set. We then will re-use the underlying
- * media instance (such as an RTP instance) on this merged stream.
+ * \details
+ * This is a bit complicated. The idea is that we already have some
+ * capabilities set, and we've now been confronted with a new stream
+ * topology.  We want to take what's been presented to us and merge
+ * those new capabilities with our own.
  *
- * The create_new parameter determines whether we should attempt to create new media
- * instances.
- * If we do not find a corresponding stream, then we create a new one. If the
- * create_new parameter is true, this created stream is made a clone of the new stream,
- * and a media instance is created. If the create_new parameter is not true, then the
- * created stream has no formats set and no media instance is created for it.
+ * For each of the new streams, we try to find a corresponding stream
+ * in our proposed capabilities.  If we find one, then we get the
+ * compatible formats of the two streams and create a new stream with
+ * those formats set.  We then will re-use the underlying media
+ * instance (such as an RTP instance) on this merged stream.
+ *
+ * The is_local parameter determines whether we should attempt to
+ * create new media instances.  If we do not find a corresponding
+ * stream, then we create a new one.  If the is_local parameter is
+ * true, this created stream is made a clone of the new stream, and a
+ * media instance is created.  If the is_local parameter is not true,
+ * then the created stream has no formats set and no media instance is
+ * created for it.
  *
- * \param current Current capabilities of the SDP state (may be NULL)
- * \param new_topology The new topology to base merged capabilities on
- * \param options The options set on the SDP state
  * \retval NULL An error occurred
  * \retval non-NULL The merged capabilities
  */
-static struct sdp_state_capabilities *merge_capabilities(const struct sdp_state_capabilities *current,
-	const struct ast_stream_topology *new_topology, const struct ast_sdp_options *options, int create_missing)
+static struct sdp_state_capabilities *merge_capabilities(const struct ast_sdp_state *sdp_state,
+	const struct ast_stream_topology *new_topology, int is_local)
 {
+	const struct sdp_state_capabilities *local = sdp_state->proposed_capabilities;
 	struct sdp_state_capabilities *joint_capabilities;
-	struct ast_stream_topology *topology;
 	int media_indices[AST_MEDIA_TYPE_END] = {0};
 	int i;
+	static const char dummy_name[] = "dummy";
 
-	ast_assert(current != NULL);
+	ast_assert(local != NULL);
 
 	joint_capabilities = ast_calloc(1, sizeof(*joint_capabilities));
 	if (!joint_capabilities) {
@@ -644,20 +710,18 @@ static struct sdp_state_capabilities *merge_capabilities(const struct sdp_state_
 		goto fail;
 	}
 
-	if (AST_VECTOR_INIT(&joint_capabilities->streams, AST_VECTOR_SIZE(&current->streams))) {
+	if (AST_VECTOR_INIT(&joint_capabilities->streams, AST_VECTOR_SIZE(&local->streams))) {
 		goto fail;
 	}
-	ast_sockaddr_copy(&joint_capabilities->connection_address, &current->connection_address);
-	topology = current->topology;
+	ast_sockaddr_copy(&joint_capabilities->connection_address, &local->connection_address);
 
 	for (i = 0; i < ast_stream_topology_get_count(new_topology); ++i) {
 		enum ast_media_type new_stream_type;
 		struct ast_stream *new_stream;
-		struct ast_stream *current_stream;
+		struct ast_stream *local_stream;
 		struct ast_stream *joint_stream;
-		struct sdp_state_stream *current_state_stream;
 		struct sdp_state_stream *joint_state_stream;
-		int current_index;
+		int local_index;
 
 		joint_state_stream = ast_calloc(1, sizeof(*joint_state_stream));
 		if (!joint_state_stream) {
@@ -667,26 +731,57 @@ static struct sdp_state_capabilities *merge_capabilities(const struct sdp_state_
 		new_stream = ast_stream_topology_get_stream(new_topology, i);
 		new_stream_type = ast_stream_get_type(new_stream);
 
-		current_index = get_corresponding_index(topology, new_stream_type, media_indices);
-		if (current_index >= 0) {
-			current_stream = ast_stream_topology_get_stream(topology, current_index);
-			joint_stream = merge_streams(current_stream, new_stream);
+		local_index = get_corresponding_index(local->topology, new_stream_type, media_indices);
+		if (0 <= local_index) {
+			local_stream = ast_stream_topology_get_stream(local->topology, local_index);
+			if (!strcmp(ast_stream_get_name(local_stream), dummy_name)) {
+				/* The local stream is a non-exixtent dummy stream. */
+				local_stream = NULL;
+			}
+		} else {
+			local_stream = NULL;
+		}
+		if (local_stream) {
+			struct sdp_state_stream *local_state_stream;
+			struct ast_rtp_codecs *codecs;
+
+			if (is_local) {
+				/* Replace the local stream with the new local stream. */
+				joint_stream = ast_stream_clone(new_stream);
+			} else {
+				joint_stream = merge_streams(local_stream, new_stream);
+			}
 			if (!joint_stream) {
 				sdp_state_stream_free(joint_state_stream);
 				goto fail;
 			}
 
-			current_state_stream = AST_VECTOR_GET(&current->streams, current_index);
-			joint_state_stream->type = current_state_stream->type;
+			local_state_stream = AST_VECTOR_GET(&local->streams, local_index);
+			joint_state_stream->type = local_state_stream->type;
 
 			switch (joint_state_stream->type) {
 			case AST_MEDIA_TYPE_AUDIO:
 			case AST_MEDIA_TYPE_VIDEO:
-				joint_state_stream->instance = ao2_bump(current_state_stream->instance);
+				joint_state_stream->rtp = ao2_bump(local_state_stream->rtp);
+				if (is_local) {
+					break;
+				}
+				codecs = ast_stream_get_data(new_stream, AST_STREAM_DATA_RTP_CODECS);
+				ast_assert(codecs != NULL);
+				if (sdp_state->role == SDP_ROLE_ANSWERER) {
+					/*
+					 * Setup rx payload type mapping to prefer the mapping
+					 * from the peer that the RFC says we SHOULD use.
+					 */
+					ast_rtp_codecs_payloads_xover(codecs, codecs, NULL);
+				}
+				ast_rtp_codecs_payloads_copy(codecs,
+					ast_rtp_instance_get_codecs(joint_state_stream->rtp->instance),
+					joint_state_stream->rtp->instance);
 				break;
 			case AST_MEDIA_TYPE_IMAGE:
-				joint_state_stream->udptl = ao2_bump(current_state_stream->udptl);
-				joint_state_stream->t38_local_params = current_state_stream->t38_local_params;
+				joint_state_stream->udptl = ao2_bump(local_state_stream->udptl);
+				joint_state_stream->t38_local_params = local_state_stream->t38_local_params;
 				break;
 			case AST_MEDIA_TYPE_UNKNOWN:
 			case AST_MEDIA_TYPE_TEXT:
@@ -694,13 +789,14 @@ static struct sdp_state_capabilities *merge_capabilities(const struct sdp_state_
 				break;
 			}
 
-			if (!ast_sockaddr_isnull(&current_state_stream->connection_address)) {
-				ast_sockaddr_copy(&joint_state_stream->connection_address, &current_state_stream->connection_address);
+			if (!ast_sockaddr_isnull(&local_state_stream->connection_address)) {
+				ast_sockaddr_copy(&joint_state_stream->connection_address,
+					&local_state_stream->connection_address);
 			} else {
 				ast_sockaddr_setnull(&joint_state_stream->connection_address);
 			}
-			joint_state_stream->locally_held = current_state_stream->locally_held;
-		} else if (create_missing) {
+			joint_state_stream->locally_held = local_state_stream->locally_held;
+		} else if (is_local) {
 			/* We don't have a stream state that corresponds to the stream in the new topology, so
 			 * create a stream state as appropriate.
 			 */
@@ -713,15 +809,16 @@ static struct sdp_state_capabilities *merge_capabilities(const struct sdp_state_
 			switch (new_stream_type) {
 			case AST_MEDIA_TYPE_AUDIO:
 			case AST_MEDIA_TYPE_VIDEO:
-				joint_state_stream->instance = create_rtp(options, new_stream_type);
-				if (!joint_state_stream->instance) {
+				joint_state_stream->rtp = create_rtp(sdp_state->options,
+					new_stream_type);
+				if (!joint_state_stream->rtp) {
 					ast_stream_free(joint_stream);
 					sdp_state_stream_free(joint_state_stream);
 					goto fail;
 				}
 				break;
 			case AST_MEDIA_TYPE_IMAGE:
-				joint_state_stream->udptl = create_udptl(options);
+				joint_state_stream->udptl = create_udptl(sdp_state->options);
 				if (!joint_state_stream->udptl) {
 					ast_stream_free(joint_stream);
 					sdp_state_stream_free(joint_state_stream);
@@ -740,7 +837,7 @@ static struct sdp_state_capabilities *merge_capabilities(const struct sdp_state_
 			 * dummy stream to go in its place so that the resulting SDP created will contain
 			 * the stream but will have no port or codecs set
 			 */
-			joint_stream = ast_stream_alloc("dummy", new_stream_type);
+			joint_stream = ast_stream_alloc(dummy_name, new_stream_type);
 			if (!joint_stream) {
 				sdp_state_stream_free(joint_state_stream);
 				goto fail;
@@ -889,24 +986,33 @@ static void update_ice(const struct ast_sdp_state *state, struct ast_rtp_instanc
  * sides.
  *
  * \param state The SDP state in which SDPs have been negotiated
- * \param rtp The RTP instance that is being updated
+ * \param rtp The RTP wrapper that is being updated
  * \param options Our locally-supported SDP options
  * \param remote_sdp The SDP we most recently received
  * \param remote_m_line The remote SDP stream that corresponds to the RTP instance we are modifying
  */
-static void update_rtp_after_merge(const struct ast_sdp_state *state, struct ast_rtp_instance *rtp,
+static void update_rtp_after_merge(const struct ast_sdp_state *state,
+	struct sdp_state_rtp *rtp,
     const struct ast_sdp_options *options,
 	const struct ast_sdp *remote_sdp,
 	const struct ast_sdp_m_line *remote_m_line)
 {
-	if (ast_sdp_options_get_rtcp_mux(options) && ast_sdp_m_find_attribute(remote_m_line, "rtcp-mux", -1)) {
-		ast_rtp_instance_set_prop(rtp, AST_RTP_PROPERTY_RTCP, AST_RTP_INSTANCE_RTCP_MUX);
+	if (!rtp) {
+		/* This is a dummy stream */
+		return;
+	}
+
+	if (ast_sdp_options_get_rtcp_mux(options)
+		&& ast_sdp_m_find_attribute(remote_m_line, "rtcp-mux", -1)) {
+		ast_rtp_instance_set_prop(rtp->instance, AST_RTP_PROPERTY_RTCP,
+			AST_RTP_INSTANCE_RTCP_MUX);
 	} else {
-		ast_rtp_instance_set_prop(rtp, AST_RTP_PROPERTY_RTCP, AST_RTP_INSTANCE_RTCP_STANDARD);
+		ast_rtp_instance_set_prop(rtp->instance, AST_RTP_PROPERTY_RTCP,
+			AST_RTP_INSTANCE_RTCP_STANDARD);
 	}
 
 	if (ast_sdp_options_get_ice(options) == AST_SDP_ICE_ENABLED_STANDARD) {
-		update_ice(state, rtp, options, remote_sdp, remote_m_line);
+		update_ice(state, rtp->instance, options, remote_sdp, remote_m_line);
 	}
 }
 
@@ -935,6 +1041,11 @@ static void update_udptl_after_merge(const struct ast_sdp_state *state, struct s
 	unsigned int fax_max_datagram;
 	struct ast_sockaddr *addrs;
 
+	if (!udptl) {
+		/* This is a dummy stream */
+		return;
+	}
+
 	a_line = ast_sdp_m_find_attribute(remote_m_line, "t38faxmaxdatagram", -1);
 	if (!a_line) {
 		a_line = ast_sdp_m_find_attribute(remote_m_line, "t38maxdatagram", -1);
@@ -1007,13 +1118,13 @@ static int merge_sdps(struct ast_sdp_state *sdp_state, const struct ast_sdp *rem
 	struct ast_stream_topology *remote_capabilities;
 	int i;
 
-	remote_capabilities = ast_get_topology_from_sdp(remote_sdp);
+	remote_capabilities = ast_get_topology_from_sdp(remote_sdp,
+		sdp_state->options->g726_non_standard);
 	if (!remote_capabilities) {
 		return -1;
 	}
 
-	joint_capabilities = merge_capabilities(sdp_state->proposed_capabilities,
-		remote_capabilities, sdp_state->options, 0);
+	joint_capabilities = merge_capabilities(sdp_state, remote_capabilities, 0);
 	ast_stream_topology_free(remote_capabilities);
 	if (!joint_capabilities) {
 		return -1;
@@ -1038,7 +1149,7 @@ static int merge_sdps(struct ast_sdp_state *sdp_state, const struct ast_sdp *rem
 		switch (ast_stream_get_type(ast_stream_topology_get_stream(joint_capabilities->topology, i))) {
 		case AST_MEDIA_TYPE_AUDIO:
 		case AST_MEDIA_TYPE_VIDEO:
-			update_rtp_after_merge(sdp_state, state_stream->instance, sdp_state->options,
+			update_rtp_after_merge(sdp_state, state_stream->rtp, sdp_state->options,
 				remote_sdp, ast_sdp_get_m(remote_sdp, i));
 			break;
 		case AST_MEDIA_TYPE_IMAGE:
@@ -1126,7 +1237,7 @@ int ast_sdp_state_update_local_topology(struct ast_sdp_state *sdp_state, struct
 	ast_assert(sdp_state != NULL);
 	ast_assert(streams != NULL);
 
-	capabilities = merge_capabilities(sdp_state->proposed_capabilities, streams, sdp_state->options, 1);
+	capabilities = merge_capabilities(sdp_state, streams, 1);
 	if (!capabilities) {
 		return -1;
 	}
@@ -1247,123 +1358,163 @@ static int sdp_add_m_from_rtp_stream(struct ast_sdp *sdp, const struct ast_sdp_s
 	struct ast_format_cap *caps;
 	int i;
 	int rtp_code;
+	int rtp_port;
 	int min_packet_size = 0;
 	int max_packet_size = 0;
 	enum ast_media_type media_type;
 	char tmp[64];
-	struct ast_sockaddr address_rtp;
+	struct sdp_state_stream *stream_state;
 	struct ast_rtp_instance *rtp;
 	struct ast_sdp_a_line *a_line;
 
 	stream = ast_stream_topology_get_stream(capabilities->topology, stream_index);
-	rtp = AST_VECTOR_GET(&capabilities->streams, stream_index)->instance;
 
 	ast_assert(sdp && options && stream);
 
+	caps = ast_stream_get_formats(stream);
+
+	stream_state = AST_VECTOR_GET(&capabilities->streams, stream_index);
+	if (stream_state->rtp && caps && ast_format_cap_count(caps)) {
+		rtp = stream_state->rtp->instance;
+	} else {
+		/* This is a disabled stream */
+		rtp = NULL;
+	}
+
 	if (rtp) {
+		struct ast_sockaddr address_rtp;
+
 		if (ast_sdp_state_get_stream_connection_address(sdp_state, 0, &address_rtp)) {
 			return -1;
 		}
+		rtp_port = ast_sockaddr_port(&address_rtp);
 	} else {
-		ast_sockaddr_setnull(&address_rtp);
+		rtp_port = 0;
 	}
 
 	m_line = ast_sdp_m_alloc(
 		ast_codec_media_type2str(ast_stream_get_type(stream)),
-		ast_sockaddr_port(&address_rtp), 1,
+		rtp_port, 1,
 		options->encryption != AST_SDP_ENCRYPTION_DISABLED ? "RTP/SAVP" : "RTP/AVP",
 		NULL);
 	if (!m_line) {
 		return -1;
 	}
 
-	caps = ast_stream_get_formats(stream);
+	if (rtp_port) {
+		/* Stream is not declined/disabled */
+		for (i = 0; i < ast_format_cap_count(caps); i++) {
+			struct ast_format *format = ast_format_cap_get_format(caps, i);
 
-	for (i = 0; i < ast_format_cap_count(caps); i++) {
-		struct ast_format *format = ast_format_cap_get_format(caps, i);
+			rtp_code = ast_rtp_codecs_payload_code(ast_rtp_instance_get_codecs(rtp), 1,
+				format, 0);
+			if (rtp_code == -1) {
+				ast_log(LOG_WARNING,"Unable to get rtp codec payload code for %s\n",
+					ast_format_get_name(format));
+				ao2_ref(format, -1);
+				continue;
+			}
 
-		if ((rtp_code = ast_rtp_codecs_payload_code(ast_rtp_instance_get_codecs(rtp), 1, format, 0)) == -1) {
-			ast_log(LOG_WARNING,"Unable to get rtp codec payload code for %s\n", ast_format_get_name(format));
-			ao2_ref(format, -1);
-			continue;
-		}
+			if (ast_sdp_m_add_format(m_line, options, rtp_code, 1, format, 0)) {
+				ast_sdp_m_free(m_line);
+				ao2_ref(format, -1);
+				return -1;
+			}
+
+			if (ast_format_get_maximum_ms(format)
+				&& ((ast_format_get_maximum_ms(format) < max_packet_size)
+					|| !max_packet_size)) {
+				max_packet_size = ast_format_get_maximum_ms(format);
+			}
 
-		if (ast_sdp_m_add_format(m_line, options, rtp_code, 1, format, 0)) {
-			ast_sdp_m_free(m_line);
 			ao2_ref(format, -1);
-			return -1;
 		}
 
-		if (ast_format_get_maximum_ms(format) &&
-			((ast_format_get_maximum_ms(format) < max_packet_size) || !max_packet_size)) {
-			max_packet_size = ast_format_get_maximum_ms(format);
+		media_type = ast_stream_get_type(stream);
+		if (media_type != AST_MEDIA_TYPE_VIDEO
+			&& (options->dtmf == AST_SDP_DTMF_RFC_4733 || options->dtmf == AST_SDP_DTMF_AUTO)) {
+			i = AST_RTP_DTMF;
+			rtp_code = ast_rtp_codecs_payload_code(
+				ast_rtp_instance_get_codecs(rtp), 0, NULL, i);
+			if (-1 < rtp_code) {
+				if (ast_sdp_m_add_format(m_line, options, rtp_code, 0, NULL, i)) {
+					ast_sdp_m_free(m_line);
+					return -1;
+				}
+
+				snprintf(tmp, sizeof(tmp), "%d 0-16", rtp_code);
+				a_line = ast_sdp_a_alloc("fmtp", tmp);
+				if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
+					ast_sdp_a_free(a_line);
+					ast_sdp_m_free(m_line);
+					return -1;
+				}
+			}
 		}
 
-		ao2_ref(format, -1);
-	}
+		/* If ptime is set add it as an attribute */
+		min_packet_size = ast_rtp_codecs_get_framing(ast_rtp_instance_get_codecs(rtp));
+		if (!min_packet_size) {
+			min_packet_size = ast_format_cap_get_framing(caps);
+		}
+		if (min_packet_size) {
+			snprintf(tmp, sizeof(tmp), "%d", min_packet_size);
 
-	media_type = ast_stream_get_type(stream);
-	if (rtp && media_type != AST_MEDIA_TYPE_VIDEO
-		&& (options->dtmf == AST_SDP_DTMF_RFC_4733 || options->dtmf == AST_SDP_DTMF_AUTO)) {
-		i = AST_RTP_DTMF;
-		rtp_code = ast_rtp_codecs_payload_code(
-			ast_rtp_instance_get_codecs(rtp), 0, NULL, i);
-		if (-1 < rtp_code) {
-			if (ast_sdp_m_add_format(m_line, options, rtp_code, 0, NULL, i)) {
+			a_line = ast_sdp_a_alloc("ptime", tmp);
+			if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
+				ast_sdp_a_free(a_line);
 				ast_sdp_m_free(m_line);
 				return -1;
 			}
+		}
 
-			snprintf(tmp, sizeof(tmp), "%d 0-16", rtp_code);
-			a_line = ast_sdp_a_alloc("fmtp", tmp);
+		if (max_packet_size) {
+			snprintf(tmp, sizeof(tmp), "%d", max_packet_size);
+			a_line = ast_sdp_a_alloc("maxptime", tmp);
 			if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
 				ast_sdp_a_free(a_line);
 				ast_sdp_m_free(m_line);
 				return -1;
 			}
 		}
-	}
 
-	if (ast_sdp_m_get_a_count(m_line) == 0) {
-		ast_sdp_m_free(m_line);
-		return 0;
-	}
-
-	/* If ptime is set add it as an attribute */
-	min_packet_size = ast_rtp_codecs_get_framing(ast_rtp_instance_get_codecs(rtp));
-	if (!min_packet_size) {
-		min_packet_size = ast_format_cap_get_framing(caps);
-	}
-	if (min_packet_size) {
-		snprintf(tmp, sizeof(tmp), "%d", min_packet_size);
-
-		a_line = ast_sdp_a_alloc("ptime", tmp);
+		a_line = ast_sdp_a_alloc(ast_sdp_state_get_locally_held(sdp_state, stream_index)
+			? "sendonly" : "sendrecv", "");
 		if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
 			ast_sdp_a_free(a_line);
 			ast_sdp_m_free(m_line);
 			return -1;
 		}
-	}
 
-	if (max_packet_size) {
-		snprintf(tmp, sizeof(tmp), "%d", max_packet_size);
-		a_line = ast_sdp_a_alloc("maxptime", tmp);
-		if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
-			ast_sdp_a_free(a_line);
+		add_ssrc_attributes(m_line, options, rtp);
+	} else {
+		/* Declined/disabled stream */
+		struct ast_sdp_payload *payload;
+		const char *fmt;
+
+		/*
+		 * Add a static payload type placeholder to the declined/disabled stream.
+		 *
+		 * XXX We should use the default payload type in the received offer but
+		 * we don't have that available.
+		 */
+		switch (ast_stream_get_type(stream)) {
+		default:
+		case AST_MEDIA_TYPE_AUDIO:
+			fmt = "0"; /* ulaw */
+			break;
+		case AST_MEDIA_TYPE_VIDEO:
+			fmt = "31"; /* H.261 */
+			break;
+		}
+		payload = ast_sdp_payload_alloc(fmt);
+		if (!payload || ast_sdp_m_add_payload(m_line, payload)) {
+			ast_sdp_payload_free(payload);
 			ast_sdp_m_free(m_line);
 			return -1;
 		}
 	}
 
-	a_line = ast_sdp_a_alloc(ast_sdp_state_get_locally_held(sdp_state, stream_index) ? "sendonly" : "sendrecv", "");
-	if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
-		ast_sdp_a_free(a_line);
-		ast_sdp_m_free(m_line);
-		return -1;
-	}
-
-	add_ssrc_attributes(m_line, options, rtp);
-
 	if (ast_sdp_add_m(sdp, m_line)) {
 		ast_sdp_m_free(m_line);
 		return -1;
@@ -1400,27 +1551,37 @@ static int sdp_add_m_from_udptl_stream(struct ast_sdp *sdp, const struct ast_sdp
 	struct ast_sdp_m_line *m_line;
 	struct ast_sdp_payload *payload;
 	char tmp[64];
-	struct ast_sockaddr address_udptl;
 	struct sdp_state_udptl *udptl;
 	struct ast_sdp_a_line *a_line;
 	struct sdp_state_stream *stream_state;
+	int udptl_port;
 
 	stream = ast_stream_topology_get_stream(capabilities->topology, stream_index);
-	udptl = AST_VECTOR_GET(&capabilities->streams, stream_index)->udptl;
 
 	ast_assert(sdp && options && stream);
 
+	stream_state = AST_VECTOR_GET(&capabilities->streams, stream_index);
+	if (stream_state->udptl) {
+		udptl = stream_state->udptl;
+	} else {
+		/* This is a disabled stream */
+		udptl = NULL;
+	}
+
 	if (udptl) {
+		struct ast_sockaddr address_udptl;
+
 		if (ast_sdp_state_get_stream_connection_address(sdp_state, 0, &address_udptl)) {
 			return -1;
 		}
+		udptl_port = ast_sockaddr_port(&address_udptl);
 	} else {
-		ast_sockaddr_setnull(&address_udptl);
+		udptl_port = 0;
 	}
 
 	m_line = ast_sdp_m_alloc(
 		ast_codec_media_type2str(ast_stream_get_type(stream)),
-		ast_sockaddr_port(&address_udptl), 1, "udptl", NULL);
+		udptl_port, 1, "udptl", NULL);
 	if (!m_line) {
 		return -1;
 	}
@@ -1432,97 +1593,100 @@ static int sdp_add_m_from_udptl_stream(struct ast_sdp *sdp, const struct ast_sdp
 		return -1;
 	}
 
-	stream_state = sdp_state_get_stream(sdp_state, stream_index);
-
-	snprintf(tmp, sizeof(tmp), "%u", stream_state->t38_local_params.version);
-	a_line = ast_sdp_a_alloc("T38FaxVersion", tmp);
-	if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
-		ast_sdp_a_free(a_line);
-		ast_sdp_m_free(m_line);
-		return -1;
-	}
-
-	snprintf(tmp, sizeof(tmp), "%u", t38_get_rate(stream_state->t38_local_params.rate));
-	a_line = ast_sdp_a_alloc("T38FaxMaxBitRate", tmp);
-	if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
-		ast_sdp_a_free(a_line);
-		ast_sdp_m_free(m_line);
-		return -1;
-	}
+	if (udptl_port) {
+		/* Stream is not declined/disabled */
+		stream_state = sdp_state_get_stream(sdp_state, stream_index);
 
-	if (stream_state->t38_local_params.fill_bit_removal) {
-		a_line = ast_sdp_a_alloc("T38FaxFillBitRemoval", "");
+		snprintf(tmp, sizeof(tmp), "%u", stream_state->t38_local_params.version);
+		a_line = ast_sdp_a_alloc("T38FaxVersion", tmp);
 		if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
 			ast_sdp_a_free(a_line);
 			ast_sdp_m_free(m_line);
 			return -1;
 		}
-	}
 
-	if (stream_state->t38_local_params.transcoding_mmr) {
-		a_line = ast_sdp_a_alloc("T38FaxTranscodingMMR", "");
+		snprintf(tmp, sizeof(tmp), "%u", t38_get_rate(stream_state->t38_local_params.rate));
+		a_line = ast_sdp_a_alloc("T38FaxMaxBitRate", tmp);
 		if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
 			ast_sdp_a_free(a_line);
 			ast_sdp_m_free(m_line);
 			return -1;
 		}
-	}
 
-	if (stream_state->t38_local_params.transcoding_jbig) {
-		a_line = ast_sdp_a_alloc("T38FaxTranscodingJBIG", "");
-		if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
-			ast_sdp_a_free(a_line);
-			ast_sdp_m_free(m_line);
-			return -1;
+		if (stream_state->t38_local_params.fill_bit_removal) {
+			a_line = ast_sdp_a_alloc("T38FaxFillBitRemoval", "");
+			if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
+				ast_sdp_a_free(a_line);
+				ast_sdp_m_free(m_line);
+				return -1;
+			}
 		}
-	}
 
-	switch (stream_state->t38_local_params.rate_management) {
-	case AST_T38_RATE_MANAGEMENT_TRANSFERRED_TCF:
-		a_line = ast_sdp_a_alloc("T38FaxRateManagement", "transferredTCF");
-		if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
-			ast_sdp_a_free(a_line);
-			ast_sdp_m_free(m_line);
-			return -1;
+		if (stream_state->t38_local_params.transcoding_mmr) {
+			a_line = ast_sdp_a_alloc("T38FaxTranscodingMMR", "");
+			if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
+				ast_sdp_a_free(a_line);
+				ast_sdp_m_free(m_line);
+				return -1;
+			}
 		}
-		break;
-	case AST_T38_RATE_MANAGEMENT_LOCAL_TCF:
-		a_line = ast_sdp_a_alloc("T38FaxRateManagement", "localTCF");
-		if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
-			ast_sdp_a_free(a_line);
-			ast_sdp_m_free(m_line);
-			return -1;
+
+		if (stream_state->t38_local_params.transcoding_jbig) {
+			a_line = ast_sdp_a_alloc("T38FaxTranscodingJBIG", "");
+			if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
+				ast_sdp_a_free(a_line);
+				ast_sdp_m_free(m_line);
+				return -1;
+			}
 		}
-		break;
-	}
 
-	snprintf(tmp, sizeof(tmp), "%u", ast_udptl_get_local_max_datagram(udptl->instance));
-	a_line = ast_sdp_a_alloc("T38FaxMaxDatagram", tmp);
-	if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
-		ast_sdp_a_free(a_line);
-		ast_sdp_m_free(m_line);
-		return -1;
-	}
+		switch (stream_state->t38_local_params.rate_management) {
+		case AST_T38_RATE_MANAGEMENT_TRANSFERRED_TCF:
+			a_line = ast_sdp_a_alloc("T38FaxRateManagement", "transferredTCF");
+			if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
+				ast_sdp_a_free(a_line);
+				ast_sdp_m_free(m_line);
+				return -1;
+			}
+			break;
+		case AST_T38_RATE_MANAGEMENT_LOCAL_TCF:
+			a_line = ast_sdp_a_alloc("T38FaxRateManagement", "localTCF");
+			if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
+				ast_sdp_a_free(a_line);
+				ast_sdp_m_free(m_line);
+				return -1;
+			}
+			break;
+		}
 
-	switch (ast_udptl_get_error_correction_scheme(udptl->instance)) {
-	case UDPTL_ERROR_CORRECTION_NONE:
-		break;
-	case UDPTL_ERROR_CORRECTION_FEC:
-		a_line = ast_sdp_a_alloc("T38FaxUdpEC", "t38UDPFEC");
+		snprintf(tmp, sizeof(tmp), "%u", ast_udptl_get_local_max_datagram(udptl->instance));
+		a_line = ast_sdp_a_alloc("T38FaxMaxDatagram", tmp);
 		if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
 			ast_sdp_a_free(a_line);
 			ast_sdp_m_free(m_line);
 			return -1;
 		}
-		break;
-	case UDPTL_ERROR_CORRECTION_REDUNDANCY:
-		a_line = ast_sdp_a_alloc("T38FaxUdpEC", "t38UDPRedundancy");
-		if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
-			ast_sdp_a_free(a_line);
-			ast_sdp_m_free(m_line);
-			return -1;
+
+		switch (ast_udptl_get_error_correction_scheme(udptl->instance)) {
+		case UDPTL_ERROR_CORRECTION_NONE:
+			break;
+		case UDPTL_ERROR_CORRECTION_FEC:
+			a_line = ast_sdp_a_alloc("T38FaxUdpEC", "t38UDPFEC");
+			if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
+				ast_sdp_a_free(a_line);
+				ast_sdp_m_free(m_line);
+				return -1;
+			}
+			break;
+		case UDPTL_ERROR_CORRECTION_REDUNDANCY:
+			a_line = ast_sdp_a_alloc("T38FaxUdpEC", "t38UDPRedundancy");
+			if (!a_line || ast_sdp_m_add_a(m_line, a_line)) {
+				ast_sdp_a_free(a_line);
+				ast_sdp_m_free(m_line);
+				return -1;
+			}
+			break;
 		}
-		break;
 	}
 
 	if (ast_sdp_add_m(sdp, m_line)) {

tests/test_sdp.c

@@ -276,6 +276,7 @@ AST_TEST_DEFINE(find_attr)
 	enum ast_test_result_state res = AST_TEST_PASS;
 	struct ast_sdp_m_line *m_line;
 	struct ast_sdp_a_line *a_line;
+	int idx;
 
 	switch(cmd) {
 	case TEST_INIT:
@@ -283,7 +284,7 @@ AST_TEST_DEFINE(find_attr)
 		info->category = "/main/sdp/";
 		info->summary = "Ensure that finding attributes works as expected";
 		info->description =
-			"An SDP m-line is created, and two attributes are added.\n"
+			"A SDP m-line is created, and attributes are added.\n"
 			"We then attempt a series of attribute-finding calls that are expected to work\n"
 			"followed by a series of attribute-finding calls that are expected fo fail.";
 		return AST_TEST_NOT_RUN;
@@ -302,6 +303,12 @@ AST_TEST_DEFINE(find_attr)
 		goto end;
 	}
 	ast_sdp_m_add_a(m_line, a_line);
+	a_line = ast_sdp_a_alloc("foo", "0 bee");
+	if (!a_line) {
+		res = AST_TEST_FAIL;
+		goto end;
+	}
+	ast_sdp_m_add_a(m_line, a_line);
 
 	a_line = ast_sdp_a_alloc("baz", "howdy");
 	if (!a_line) {
@@ -312,21 +319,77 @@ AST_TEST_DEFINE(find_attr)
 
 	/* These should work */
 	a_line = ast_sdp_m_find_attribute(m_line, "foo", 0);
-	if (!a_line) {
+	if (!a_line || strcmp(a_line->value, "0 bar")) {
 		ast_test_status_update(test, "Failed to find attribute 'foo' with payload '0'\n");
 		res = AST_TEST_FAIL;
 	}
 	a_line = ast_sdp_m_find_attribute(m_line, "foo", -1);
-	if (!a_line) {
+	if (!a_line || strcmp(a_line->value, "0 bar")) {
 		ast_test_status_update(test, "Failed to find attribute 'foo' with unspecified payload\n");
 		res = AST_TEST_FAIL;
 	}
 	a_line = ast_sdp_m_find_attribute(m_line, "baz", -1);
-	if (!a_line) {
+	if (!a_line || strcmp(a_line->value, "howdy")) {
 		ast_test_status_update(test, "Failed to find attribute 'baz' with unspecified payload\n");
 		res = AST_TEST_FAIL;
 	}
 
+	idx = ast_sdp_m_find_a_first(m_line, "foo", 0);
+	if (idx < 0) {
+		ast_test_status_update(test, "Failed to find first attribute 'foo' with payload '0'\n");
+		res = AST_TEST_FAIL;
+		goto end;
+	}
+	a_line = ast_sdp_m_get_a(m_line, idx);
+	if (!a_line || strcmp(a_line->value, "0 bar")) {
+		ast_test_status_update(test, "Find first attribute 'foo' with payload '0' didn't match\n");
+		res = AST_TEST_FAIL;
+	}
+	idx = ast_sdp_m_find_a_next(m_line, idx, "foo", 0);
+	if (idx < 0) {
+		ast_test_status_update(test, "Failed to find next attribute 'foo' with payload '0'\n");
+		res = AST_TEST_FAIL;
+		goto end;
+	}
+	a_line = ast_sdp_m_get_a(m_line, idx);
+	if (!a_line || strcmp(a_line->value, "0 bee")) {
+		ast_test_status_update(test, "Find next attribute 'foo' with payload '0' didn't match\n");
+		res = AST_TEST_FAIL;
+	}
+	idx = ast_sdp_m_find_a_next(m_line, idx, "foo", 0);
+	if (0 <= idx) {
+		ast_test_status_update(test, "Find next attribute 'foo' with payload '0' found too many\n");
+		res = AST_TEST_FAIL;
+	}
+
+	idx = ast_sdp_m_find_a_first(m_line, "foo", -1);
+	if (idx < 0) {
+		ast_test_status_update(test, "Failed to find first attribute 'foo' with unspecified payload\n");
+		res = AST_TEST_FAIL;
+		goto end;
+	}
+	a_line = ast_sdp_m_get_a(m_line, idx);
+	if (!a_line || strcmp(a_line->value, "0 bar")) {
+		ast_test_status_update(test, "Find first attribute 'foo' with unspecified payload didn't match\n");
+		res = AST_TEST_FAIL;
+	}
+	idx = ast_sdp_m_find_a_next(m_line, idx, "foo", -1);
+	if (idx < 0) {
+		ast_test_status_update(test, "Failed to find next attribute 'foo' with unspecified payload\n");
+		res = AST_TEST_FAIL;
+		goto end;
+	}
+	a_line = ast_sdp_m_get_a(m_line, idx);
+	if (!a_line || strcmp(a_line->value, "0 bee")) {
+		ast_test_status_update(test, "Find next attribute 'foo' with unspecified payload didn't match\n");
+		res = AST_TEST_FAIL;
+	}
+	idx = ast_sdp_m_find_a_next(m_line, idx, "foo", -1);
+	if (0 <= idx) {
+		ast_test_status_update(test, "Find next attribute 'foo' with unspecified payload found too many\n");
+		res = AST_TEST_FAIL;
+	}
+
 	/* These should fail */
 	a_line = ast_sdp_m_find_attribute(m_line, "foo", 1);
 	if (a_line) {
@@ -345,7 +408,7 @@ AST_TEST_DEFINE(find_attr)
 	}
 	a_line = ast_sdp_m_find_attribute(m_line, "wibble", -1);
 	if (a_line) {
-		ast_test_status_update(test, "Found non-existent attribute 'foo' with unspecified payload\n");
+		ast_test_status_update(test, "Found non-existent attribute 'wibble' with unspecified payload\n");
 		res = AST_TEST_FAIL;
 	}
 
@@ -623,10 +686,14 @@ AST_TEST_DEFINE(sdp_to_topology)
 		goto end;
 	}
 
-	topology = ast_get_topology_from_sdp(sdp);
+	topology = ast_get_topology_from_sdp(sdp, 0);
+	if (!topology) {
+		res = AST_TEST_FAIL;
+		goto end;
+	}
 
 	if (ast_stream_topology_get_count(topology) != 3) {
-		ast_test_status_update(test, "Unexpected topology count '%d'. Expecting 2\n",
+		ast_test_status_update(test, "Unexpected topology count '%d'. Expecting 3\n",
 			ast_stream_topology_get_count(topology));
 		res = AST_TEST_FAIL;
 		goto end;
@@ -665,11 +732,9 @@ static int validate_merged_sdp(struct ast_test *test, const struct ast_sdp *sdp)
 	}
 
 	m_line = ast_sdp_get_m(sdp, 0);
-
 	if (validate_m_line(test, m_line, "audio", 1)) {
 		return -1;
 	}
-
 	if (validate_rtpmap(test, m_line, "PCMU")) {
 		return -1;
 	}
@@ -678,29 +743,29 @@ static int validate_merged_sdp(struct ast_test *test, const struct ast_sdp *sdp)
 	if (!validate_rtpmap(test, m_line, "PCMA")) {
 		return -1;
 	}
-
 	if (!validate_rtpmap(test, m_line, "G722")) {
 		return -1;
 	}
-
 	if (!validate_rtpmap(test, m_line, "opus")) {
 		return -1;
 	}
 
 	m_line = ast_sdp_get_m(sdp, 1);
-
 	if (validate_m_line(test, m_line, "video", 1)) {
 		return -1;
 	}
-
 	if (validate_rtpmap(test, m_line, "VP8")) {
 		return -1;
 	}
-
 	if (!validate_rtpmap(test, m_line, "H264")) {
 		return -1;
 	}
 
+	m_line = ast_sdp_get_m(sdp, 2);
+	if (validate_m_line(test, m_line, "image", 1)) {
+		return -1;
+	}
+
 	return 0;
 }
 
@@ -715,10 +780,12 @@ AST_TEST_DEFINE(sdp_merge_symmetric)
 	static const struct sdp_format offerer_formats[] = {
 		{ AST_MEDIA_TYPE_AUDIO, "ulaw,alaw,g722,opus" },
 		{ AST_MEDIA_TYPE_VIDEO, "h264,vp8" },
+		{ AST_MEDIA_TYPE_IMAGE, "t38" },
 	};
 	static const struct sdp_format answerer_formats[] = {
 		{ AST_MEDIA_TYPE_AUDIO, "ulaw" },
 		{ AST_MEDIA_TYPE_VIDEO, "vp8" },
+		{ AST_MEDIA_TYPE_IMAGE, "t38" },
 	};
 
 	switch(cmd) {
@@ -791,8 +858,10 @@ AST_TEST_DEFINE(sdp_merge_crisscross)
 	static const struct sdp_format offerer_formats[] = {
 		{ AST_MEDIA_TYPE_AUDIO, "ulaw,alaw,g722,opus" },
 		{ AST_MEDIA_TYPE_VIDEO, "h264,vp8" },
+		{ AST_MEDIA_TYPE_IMAGE, "t38" },
 	};
 	static const struct sdp_format answerer_formats[] = {
+		{ AST_MEDIA_TYPE_IMAGE, "t38" },
 		{ AST_MEDIA_TYPE_VIDEO, "vp8" },
 		{ AST_MEDIA_TYPE_AUDIO, "ulaw" },
 	};
@@ -858,6 +927,153 @@ end:
 	return res;
 }
 
+static int validate_merged_sdp_asymmetric(struct ast_test *test, const struct ast_sdp *sdp, int is_offer)
+{
+	struct ast_sdp_m_line *m_line;
+	const char *side = is_offer ? "Offer side" : "Answer side";
+
+	if (!sdp) {
+		ast_test_status_update(test, "%s does not have a SDP\n", side);
+		return -1;
+	}
+
+	/* Stream 0 */
+	m_line = ast_sdp_get_m(sdp, 0);
+	if (validate_m_line(test, m_line, "audio", 1)) {
+		return -1;
+	}
+	if (!m_line->port) {
+		ast_test_status_update(test, "%s stream %d does%s have a port\n", side, 0, "n't");
+		return -1;
+	}
+	if (validate_rtpmap(test, m_line, "PCMU")) {
+		return -1;
+	}
+
+	/* The other audio formats should *NOT* be present */
+	if (!validate_rtpmap(test, m_line, "PCMA")) {
+		return -1;
+	}
+	if (!validate_rtpmap(test, m_line, "G722")) {
+		return -1;
+	}
+	if (!validate_rtpmap(test, m_line, "opus")) {
+		return -1;
+	}
+
+	/* The remaining streams should be declined */
+
+	/* Stream 1 */
+	m_line = ast_sdp_get_m(sdp, 1);
+	if (validate_m_line(test, m_line, "audio", 1)) {
+		return -1;
+	}
+	if (m_line->port) {
+		ast_test_status_update(test, "%s stream %d does%s have a port\n", side, 1, "");
+		return -1;
+	}
+
+	/* Stream 2 */
+	m_line = ast_sdp_get_m(sdp, 2);
+	if (validate_m_line(test, m_line, "video", 1)) {
+		return -1;
+	}
+	if (m_line->port) {
+		ast_test_status_update(test, "%s stream %d does%s have a port\n", side, 2, "");
+		return -1;
+	}
+
+	/* Stream 3 */
+	m_line = ast_sdp_get_m(sdp, 3);
+	if (validate_m_line(test, m_line, "image", 1)) {
+		return -1;
+	}
+	if (m_line->port) {
+		ast_test_status_update(test, "%s stream %d does%s have a port\n", side, 3, "");
+		return -1;
+	}
+
+	return 0;
+}
+
+AST_TEST_DEFINE(sdp_merge_asymmetric)
+{
+	enum ast_test_result_state res = AST_TEST_PASS;
+	struct ast_sdp_state *sdp_state_offerer = NULL;
+	struct ast_sdp_state *sdp_state_answerer = NULL;
+	const struct ast_sdp *offerer_sdp;
+	const struct ast_sdp *answerer_sdp;
+
+	static const struct sdp_format offerer_formats[] = {
+		{ AST_MEDIA_TYPE_AUDIO, "ulaw,alaw,g722,opus" },
+		{ AST_MEDIA_TYPE_AUDIO, "ulaw" },
+		{ AST_MEDIA_TYPE_VIDEO, "h261" },
+		{ AST_MEDIA_TYPE_IMAGE, "t38" },
+	};
+	static const struct sdp_format answerer_formats[] = {
+		{ AST_MEDIA_TYPE_AUDIO, "ulaw" },
+	};
+
+	switch(cmd) {
+	case TEST_INIT:
+		info->name = "sdp_merge_asymmetric";
+		info->category = "/main/sdp/";
+		info->summary = "Merge two SDPs with an asymmetric number of streams";
+		info->description =
+			"SDP 1 offers a four stream topology: Audio,Audio,Video,T.38\n"
+			"SDP 2 only has a single audio stream topology\n"
+			"We ensure that both local SDPs have the expected stream types and\n"
+			"the expected declined streams";
+		return AST_TEST_NOT_RUN;
+	case TEST_EXECUTE:
+		break;
+	}
+
+	sdp_state_offerer = build_sdp_state(ARRAY_LEN(offerer_formats), offerer_formats, NULL);
+	if (!sdp_state_offerer) {
+		res = AST_TEST_FAIL;
+		goto end;
+	}
+
+	sdp_state_answerer = build_sdp_state(ARRAY_LEN(answerer_formats), answerer_formats, NULL);
+	if (!sdp_state_answerer) {
+		res = AST_TEST_FAIL;
+		goto end;
+	}
+
+	offerer_sdp = ast_sdp_state_get_local_sdp(sdp_state_offerer);
+	if (!offerer_sdp) {
+		res = AST_TEST_FAIL;
+		goto end;
+	}
+
+	ast_sdp_state_set_remote_sdp(sdp_state_answerer, offerer_sdp);
+	answerer_sdp = ast_sdp_state_get_local_sdp(sdp_state_answerer);
+	if (!answerer_sdp) {
+		res = AST_TEST_FAIL;
+		goto end;
+	}
+
+	ast_sdp_state_set_remote_sdp(sdp_state_offerer, answerer_sdp);
+
+#if defined(XXX_TODO_NEED_TO_HANDLE_DECLINED_STREAMS_ON_OFFER_SIDE)
+	/* Get the offerer SDP again because it's now going to be the joint SDP */
+	offerer_sdp = ast_sdp_state_get_local_sdp(sdp_state_offerer);
+	if (validate_merged_sdp_asymmetric(test, offerer_sdp, 1)) {
+		res = AST_TEST_FAIL;
+	}
+#endif
+	if (validate_merged_sdp_asymmetric(test, answerer_sdp, 0)) {
+		res = AST_TEST_FAIL;
+	}
+
+end:
+	ast_sdp_state_free(sdp_state_offerer);
+	ast_sdp_state_free(sdp_state_answerer);
+
+	return res;
+}
+
 static int validate_ssrc(struct ast_test *test, struct ast_sdp_m_line *m_line,
 	struct ast_rtp_instance *rtp)
 {
@@ -972,6 +1188,7 @@ static int unload_module(void)
 	AST_TEST_UNREGISTER(sdp_to_topology);
 	AST_TEST_UNREGISTER(sdp_merge_symmetric);
 	AST_TEST_UNREGISTER(sdp_merge_crisscross);
+	AST_TEST_UNREGISTER(sdp_merge_asymmetric);
 	AST_TEST_UNREGISTER(sdp_ssrc_attributes);
 
 	return 0;
@@ -986,6 +1203,7 @@ static int load_module(void)
 	AST_TEST_REGISTER(sdp_to_topology);
 	AST_TEST_REGISTER(sdp_merge_symmetric);
 	AST_TEST_REGISTER(sdp_merge_crisscross);
+	AST_TEST_REGISTER(sdp_merge_asymmetric);
 	AST_TEST_REGISTER(sdp_ssrc_attributes);
 
 	return AST_MODULE_LOAD_SUCCESS;