rtpbin: Add clear-ssrc action

This action signal will delegate to clear-ssrc onto the rtpssrcdemux element
associated with the session. This allow rtpbin users to clear pads and
elements for a specific ssrc that is known to no longer be in use. This
happens when a pad is reused in rtpsrc or ristsrc.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-good/-/merge_requests/736>

docs/gst_plugins_cache.json

@@ -16448,6 +16448,21 @@
                         "return-type": "void",
                         "when": "last"
                     },
+                    "clear-ssrc": {
+                        "action": true,
+                        "args": [
+                            {
+                                "name": "arg0",
+                                "type": "guint"
+                            },
+                            {
+                                "name": "arg1",
+                                "type": "guint"
+                            }
+                        ],
+                        "return-type": "void",
+                        "when": "last"
+                    },
                     "get-internal-session": {
                         "action": true,
                         "args": [

gst/rtpmanager/gstrtpbin.c

@@ -292,6 +292,7 @@ enum
   SIGNAL_GET_INTERNAL_SESSION,
   SIGNAL_GET_STORAGE,
   SIGNAL_GET_INTERNAL_STORAGE,
+  SIGNAL_CLEAR_SSRC,
 
   SIGNAL_ON_NEW_SSRC,
   SIGNAL_ON_SSRC_COLLISION,
@@ -1138,6 +1139,25 @@ gst_rtp_bin_get_internal_storage (GstRtpBin * bin, guint session_id)
   return internal_storage;
 }
 
+static void
+gst_rtp_bin_clear_ssrc (GstRtpBin * bin, guint session_id, guint32 ssrc)
+{
+  GstRtpBinSession *session;
+  GstElement *demux = NULL;
+
+  GST_RTP_BIN_LOCK (bin);
+  GST_DEBUG_OBJECT (bin, "clearing ssrc %u for session %u", ssrc, session_id);
+  session = find_session_by_id (bin, (gint) session_id);
+  if (session)
+    demux = gst_object_ref (session->demux);
+  GST_RTP_BIN_UNLOCK (bin);
+
+  if (demux) {
+    g_signal_emit_by_name (demux, "clear-ssrc", ssrc, NULL);
+    gst_object_unref (demux);
+  }
+}
+
 static GstElement *
 gst_rtp_bin_request_encoder (GstRtpBin * bin, guint session_id)
 {
@@ -2151,6 +2171,24 @@ gst_rtp_bin_class_init (GstRtpBinClass * klass)
       G_SIGNAL_RUN_LAST | G_SIGNAL_ACTION, G_STRUCT_OFFSET (GstRtpBinClass,
           get_storage), NULL, NULL, NULL, GST_TYPE_ELEMENT, 1, G_TYPE_UINT);
 
+  /**
+   * GstRtpBin::clear-ssrc:
+   * @rtpbin: the object which received the signal
+   * @id: the session id
+   * @ssrc: the ssrc
+   *
+   * Remove all pads from rtpssrcdemux element associated with the specified
+   * ssrc. This delegate the action signal to the rtpssrcdemux element
+   * associated with the specified session.
+   *
+   * Since: 1.20
+   */
+  gst_rtp_bin_signals[SIGNAL_CLEAR_SSRC] =
+      g_signal_new ("clear-ssrc", G_TYPE_FROM_CLASS (klass),
+      G_SIGNAL_RUN_LAST | G_SIGNAL_ACTION, G_STRUCT_OFFSET (GstRtpBinClass,
+          clear_ssrc), NULL, NULL, NULL, G_TYPE_NONE, 2,
+      G_TYPE_UINT, G_TYPE_UINT);
+
   /**
    * GstRtpBin::on-new-ssrc:
    * @rtpbin: the object which received the signal
@@ -2768,6 +2806,7 @@ gst_rtp_bin_class_init (GstRtpBinClass * klass)
   klass->get_storage = GST_DEBUG_FUNCPTR (gst_rtp_bin_get_storage);
   klass->get_internal_storage =
       GST_DEBUG_FUNCPTR (gst_rtp_bin_get_internal_storage);
+  klass->clear_ssrc = GST_DEBUG_FUNCPTR (gst_rtp_bin_clear_ssrc);
   klass->request_rtp_encoder = GST_DEBUG_FUNCPTR (gst_rtp_bin_request_encoder);
   klass->request_rtp_decoder = GST_DEBUG_FUNCPTR (gst_rtp_bin_request_decoder);
   klass->request_rtcp_encoder = GST_DEBUG_FUNCPTR (gst_rtp_bin_request_encoder);

gst/rtpmanager/gstrtpbin.h

@@ -117,6 +117,7 @@ struct _GstRtpBinClass {
   RTPSession* (*get_internal_session) (GstRtpBin *rtpbin, guint session);
   GstElement* (*get_storage)          (GstRtpBin *rtpbin, guint session);
   GObject*    (*get_internal_storage) (GstRtpBin *rtpbin, guint session);
+  void        (*clear_ssrc)           (GstRtpBin *rtpbin, guint session, guint32 ssrc);
 
   /* session manager signals */
   void     (*on_new_ssrc)       (GstRtpBin *rtpbin, guint session, guint32 ssrc);