--- a/libervia/backend/plugins/plugin_xep_0167/mapping.py	Tue Oct 03 15:20:00 2023 +0200
+++ b/libervia/backend/plugins/plugin_xep_0167/mapping.py	Tue Oct 03 15:25:52 2023 +0200
@@ -44,7 +44,7 @@
 
 
 def generate_sdp_from_session(
-    session: dict, local: bool = False, port: int = 9999
+    session: dict, local: bool = False, port: int = 9
 ) -> str:
     """Generate an SDP string from session data.
 
@@ -78,6 +78,7 @@
 
     @return: The generated SDP string.
     """
+    contents = session["contents"]
     sdp_lines = ["v=0"]
 
     # Add originator (o=) line after the version (v=) line
@@ -101,10 +102,9 @@
     all_senders = {c["senders"] for c in session["contents"].values()}
     # if we don't have a common senders for all contents, we set them at media level
     senders = all_senders.pop() if len(all_senders) == 1 else None
-    if senders is not None:
-        sdp_lines.append(senders_to_sdp(senders, session))
 
     sdp_lines.append("a=msid-semantic:WMS *")
+    sdp_lines.append("a=ice-options:trickle")
 
     host.trigger.point(
         "XEP-0167_generate_sdp_session",
@@ -114,7 +114,6 @@
         triggers_no_cancel=True
     )
 
-    contents = session["contents"]
     for content_name, content_data in contents.items():
         app_data_key = "local_data" if local else "peer_data"
         application_data = content_data["application_data"]
@@ -131,16 +130,25 @@
         sdp_lines.append(f"c={network_type} {address_type} {connection_address}")
 
         sdp_lines.append(f"a=mid:{content_name}")
+        if senders is not None:
+            sdp_lines.append(senders_to_sdp(senders, session))
 
         # stream direction
         if senders is None:
             sdp_lines.append(senders_to_sdp(content_data["senders"], session))
 
+
         # Generate a= lines for rtpmap and fmtp
         for pt_id, pt in payload_types.items():
             name = pt["name"]
             clockrate = pt.get("clockrate", "")
-            sdp_lines.append(f"a=rtpmap:{pt_id} {name}/{clockrate}")
+
+            # Check if "channels" is in pt and append it to the line
+            channels = pt.get("channels")
+            if channels:
+                sdp_lines.append(f"a=rtpmap:{pt_id} {name}/{clockrate}/{channels}")
+            else:
+                sdp_lines.append(f"a=rtpmap:{pt_id} {name}/{clockrate}")
 
             if "ptime" in pt:
                 sdp_lines.append(f"a=ptime:{pt['ptime']}")
@@ -383,7 +391,9 @@
                     algorithm, fingerprint = parts[0], parts[1]
                     fingerprint_data = {"hash": algorithm, "fingerprint": fingerprint}
                     if transport_data is not None:
-                        transport_data["fingerprint"] = fingerprint_data
+                        transport_data.setdefault("fingerprint", {}).update(
+                            fingerprint_data
+                        )
                 elif attribute == "setup":
                     assert transport_data is not None
                     setup = parts[0]
@@ -429,6 +439,7 @@
         log.debug(f"cleaning remaining private data {key!r}")
         del call_data[key]
 
+    # FIXME: is this really useful?
     # ICE candidates may only be specified for the first media, this
     # duplicate the candidate for the other in this case
     all_media = {k:v for k,v in call_data.items() if k in ("audio", "video")}