playbin: Implement context caching for sinks that are not in playsink yet

gst/playback/gstplaybin2.c

@@ -470,6 +470,8 @@ struct _GstPlayBin
   } duration[5];                /* cached durations */
 
   guint64 ring_buffer_max_size; /* 0 means disabled */
+
+  GList *contexts;
 };
 
 struct _GstPlayBinClass
@@ -1530,6 +1532,8 @@ gst_play_bin_finalize (GObject * object)
   if (playbin->velements)
     g_sequence_free (playbin->velements);
 
+  g_list_free_full (playbin->contexts, (GDestroyNotify) gst_context_unref);
+
   g_rec_mutex_clear (&playbin->lock);
   g_mutex_clear (&playbin->dyn_lock);
   g_mutex_clear (&playbin->elements_lock);
@@ -4061,6 +4065,34 @@ gst_play_bin_set_context (GstElement * element, GstContext * context)
 }
 
 /* Pass sink messages to the application, e.g. NEED_CONTEXT messages */
+static void
+gst_play_bin_update_context (GstPlayBin * playbin, GstContext * context)
+{
+  GList *l;
+  const gchar *context_type;
+
+  GST_OBJECT_LOCK (playbin);
+  context_type = gst_context_get_context_type (context);
+  for (l = playbin->contexts; l; l = l->next) {
+    GstContext *tmp = l->data;
+    const gchar *tmp_type = gst_context_get_context_type (tmp);
+
+    /* Always store newest context but never replace
+     * a persistent one by a non-persistent one */
+    if (strcmp (context_type, tmp_type) == 0 &&
+        (gst_context_is_persistent (context) ||
+            !gst_context_is_persistent (tmp))) {
+      gst_context_replace ((GstContext **) & l->data, context);
+      break;
+    }
+  }
+  /* Not found? Add */
+  if (l != NULL)
+    playbin->contexts =
+        g_list_prepend (playbin->contexts, gst_context_ref (context));
+  GST_OBJECT_UNLOCK (playbin);
+}
+
 static GstBusSyncReply
 activate_sink_bus_handler (GstBus * bus, GstMessage * msg, GstPlayBin * playbin)
 {
@@ -4081,6 +4113,37 @@ activate_sink_bus_handler (GstBus * bus, GstMessage * msg, GstPlayBin * playbin)
       gst_element_post_message (GST_ELEMENT_CAST (playbin), msg);
     else
       gst_message_unref (msg);
+  } else if (GST_MESSAGE_TYPE (msg) == GST_MESSAGE_NEED_CONTEXT) {
+    const gchar *context_type;
+    GList *l;
+
+    gst_message_parse_context_type (msg, &context_type);
+    GST_OBJECT_LOCK (playbin);
+    for (l = playbin->contexts; l; l = l->next) {
+      GstContext *tmp = l->data;
+      const gchar *tmp_type = gst_context_get_context_type (tmp);
+
+      if (strcmp (context_type, tmp_type) == 0) {
+        gst_element_set_context (GST_ELEMENT (GST_MESSAGE_SRC (msg)), l->data);
+        break;
+      }
+    }
+    GST_OBJECT_UNLOCK (playbin);
+
+    /* Forward if we couldn't answer the message */
+    if (l == NULL) {
+      gst_element_post_message (GST_ELEMENT_CAST (playbin), msg);
+    } else {
+      gst_message_unref (msg);
+    }
+  } else if (GST_MESSAGE_TYPE (msg) == GST_MESSAGE_HAVE_CONTEXT) {
+    GstContext *context;
+
+    gst_message_parse_have_context (msg, &context);
+    gst_play_bin_update_context (playbin, context);
+    gst_context_unref (context);
+
+    gst_element_post_message (GST_ELEMENT_CAST (playbin), msg);
   } else {
     gst_element_post_message (GST_ELEMENT_CAST (playbin), msg);
   }
@@ -5379,6 +5442,7 @@ gst_play_bin_change_state (GstElement * element, GstStateChange transition)
     case GST_STATE_CHANGE_READY_TO_NULL:
     {
       guint i;
+      GList *l;
 
       /* also do missed state change down to READY */
       if (do_save)
@@ -5425,6 +5489,25 @@ gst_play_bin_change_state (GstElement * element, GstStateChange transition)
       /* make sure the groups don't perform a state change anymore until we
        * enable them again */
       groups_set_locked_state (playbin, TRUE);
+
+      /* Remove all non-persistent contexts */
+      GST_OBJECT_LOCK (playbin);
+      for (l = playbin->contexts; l;) {
+        GstContext *context = l->data;
+
+        if (!gst_context_is_persistent (context)) {
+          GList *next;
+
+          gst_context_unref (context);
+
+          next = l->next;
+          playbin->contexts = g_list_delete_link (playbin->contexts, l);
+          l = next;
+        } else {
+          l = l->next;
+        }
+      }
+      GST_OBJECT_UNLOCK (playbin);
       break;
     }
     default: