ges: Add support for gessrc as subtimeline element

Until now we have always had `gesdemux` as subtimeline elements,
the behavior when subtimelines are sources is different so we need
to support that.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/4882>

subprojects/gst-editing-services/ges/ges-internal.h

@@ -188,6 +188,9 @@ ges_timeline_set_smart_rendering (GESTimeline * timeline, gboolean rendering_sma
 G_GNUC_INTERNAL gboolean
 ges_timeline_get_smart_rendering (GESTimeline *timeline);
 
+G_GNUC_INTERNAL GstStreamCollection*
+ges_timeline_get_stream_collection (GESTimeline *timeline);
+
 G_GNUC_INTERNAL void
 ges_auto_transition_set_source (GESAutoTransition * self, GESTrackElement * source, GESEdge edge);
 
@@ -497,6 +500,7 @@ ges_source_get_rendering_smartly                      (GESSource *source);
 
 G_GNUC_INTERNAL void ges_track_set_smart_rendering     (GESTrack* track, gboolean rendering_smartly);
 G_GNUC_INTERNAL GstElement * ges_track_get_composition (GESTrack *track);
+G_GNUC_INTERNAL void ges_track_select_subtimeline_streams (GESTrack *track, GstStreamCollection *collection, GstElement *subtimeline);
 
 
 /*********************************************

subprojects/gst-editing-services/ges/ges-timeline.c

@@ -2159,6 +2159,12 @@ ges_timeline_get_smart_rendering (GESTimeline * timeline)
   return timeline->priv->rendering_smartly;
 }
 
+GstStreamCollection *
+ges_timeline_get_stream_collection (GESTimeline * timeline)
+{
+  return gst_object_ref (timeline->priv->stream_collection);
+}
+
 /**** API *****/
 /**
  * ges_timeline_new:

subprojects/gst-editing-services/ges/ges-track.c

@@ -454,40 +454,50 @@ ges_track_change_state (GstElement * element, GstStateChange transition)
       transition);
 }
 
+void
+ges_track_select_subtimeline_streams (GESTrack * track,
+    GstStreamCollection * collection, GstElement * subtimeline)
+{
+  GList *selected_streams = NULL;
+
+  for (gint i = 0; i < gst_stream_collection_get_size (collection); i++) {
+    GstStream *stream = gst_stream_collection_get_stream (collection, i);
+    GstStreamType stype = gst_stream_get_stream_type (stream);
+
+    if ((track->type == GES_TRACK_TYPE_VIDEO && stype == GST_STREAM_TYPE_VIDEO)
+        || (track->type == GES_TRACK_TYPE_AUDIO
+            && stype == GST_STREAM_TYPE_AUDIO)
+        || (stype == GST_STREAM_TYPE_UNKNOWN)) {
+
+      selected_streams =
+          g_list_append (selected_streams,
+          g_strdup (gst_stream_get_stream_id (stream)));
+    }
+  }
+
+  if (selected_streams) {
+    gst_element_send_event (subtimeline,
+        gst_event_new_select_streams (selected_streams));
+
+    g_list_free_full (selected_streams, g_free);
+  }
+}
+
 static void
 ges_track_handle_message (GstBin * bin, GstMessage * message)
 {
   GESTrack *track = GES_TRACK (bin);
 
   if (GST_MESSAGE_TYPE (message) == GST_MESSAGE_STREAM_COLLECTION) {
-    gint i;
-    GList *selected_streams = NULL;
     GstStreamCollection *collection;
 
     gst_message_parse_stream_collection (message, &collection);
-
+    if (GES_IS_TIMELINE (GST_MESSAGE_SRC (message))) {
-    for (i = 0; i < gst_stream_collection_get_size (collection); i++) {
+      ges_track_select_subtimeline_streams (track, collection,
-      GstStream *stream = gst_stream_collection_get_stream (collection, i);
+          GST_ELEMENT (GST_MESSAGE_SRC (message)));
-      GstStreamType stype = gst_stream_get_stream_type (stream);
-
-      if ((track->type == GES_TRACK_TYPE_VIDEO
-              && stype == GST_STREAM_TYPE_VIDEO)
-          || (track->type == GES_TRACK_TYPE_AUDIO
-              && stype == GST_STREAM_TYPE_AUDIO)
-          || (stype == GST_STREAM_TYPE_UNKNOWN)) {
-
-        selected_streams =
-            g_list_append (selected_streams,
-            (gchar *) gst_stream_get_stream_id (stream));
-      }
-    }
-
-    if (selected_streams) {
-      gst_element_send_event (GST_ELEMENT (GST_MESSAGE_SRC (message)),
-          gst_event_new_select_streams (selected_streams));
-      g_list_free (selected_streams);
     }
   }
+
   gst_element_post_message (GST_ELEMENT_CAST (bin), message);
 }
 

subprojects/gst-editing-services/ges/ges-uri-source.c

@@ -123,6 +123,27 @@ done:
   return res;
 }
 
+static void
+source_setup_cb (GstElement * decodebin, GstElement * source,
+    GESUriSource * self)
+{
+  GstElementFactory *factory = gst_element_get_factory (source);
+
+  if (!factory || g_strcmp0 (GST_OBJECT_NAME (factory), "gessrc")) {
+    return;
+  }
+
+  GESTrack *track = ges_track_element_get_track (self->element);
+  GESTimeline *subtimeline;
+
+  g_object_get (source, "timeline", &subtimeline, NULL);
+  GstStreamCollection *subtimeline_collection =
+      ges_timeline_get_stream_collection (subtimeline);
+
+  ges_track_select_subtimeline_streams (track, subtimeline_collection,
+      GST_ELEMENT (subtimeline));
+}
+
 GstElement *
 ges_uri_source_create_source (GESUriSource * self)
 {
@@ -139,13 +160,15 @@ ges_uri_source_create_source (GESUriSource * self)
   if (track)
     caps = ges_track_get_caps (track);
 
+  g_signal_connect (decodebin, "source-setup",
+      G_CALLBACK (source_setup_cb), self);
+
   g_object_set (decodebin, "caps", caps,
       "expose-all-streams", FALSE, "uri", self->uri, NULL);
   g_signal_connect (decodebin, "autoplug-select",
       G_CALLBACK (autoplug_select_cb), self);
 
   return decodebin;
-
 }
 
 static void