ffmpeg: make elements reusable after registry rescan

If the same instance of the plugin is asked to be initialised more that once,
instances after the first one do not register the elements properly and the
elements become not usable.

For example, if you call gst_update_registry (), is not possible to create
elements after the call since the plugin is asked to be initialised again and
does not register the elements.

Fixes #584291

ext/ffmpeg/gstffmpegdec.c

@@ -2731,12 +2731,9 @@ gst_ffmpegdec_register (GstPlugin * plugin)
     type_name = g_strdup_printf ("ffdec_%s", plugin_name);
     g_free (plugin_name);
 
-    /* if it's already registered, drop it */
+    type = g_type_from_name (type_name);
-    if (g_type_from_name (type_name)) {
-      g_free (type_name);
-      goto next;
-    }
 
+    if (!type) {
       params = g_new0 (GstFFMpegDecClassParams, 1);
       params->in_plugin = in_plugin;
       params->srccaps = gst_caps_ref (srccaps);
@@ -2745,6 +2742,7 @@ gst_ffmpegdec_register (GstPlugin * plugin)
       /* create the gtype now */
       type = g_type_register_static (GST_TYPE_ELEMENT, type_name, &typeinfo, 0);
       g_type_set_qdata (type, GST_FFDEC_PARAMS_QDATA, (gpointer) params);
+    }
 
     /* (Ronald) MPEG-4 gets a higher priority because it has been well-
      * tested and by far outperforms divxdec/xviddec - so we prefer it.

ext/ffmpeg/gstffmpegenc.c

@@ -1177,12 +1177,9 @@ gst_ffmpegenc_register (GstPlugin * plugin)
     /* construct the type */
     type_name = g_strdup_printf ("ffenc_%s", in_plugin->name);
 
-    /* if it's already registered, drop it */
+    type = g_type_from_name (type_name);
-    if (g_type_from_name (type_name)) {
-      g_free (type_name);
-      goto next;
-    }
 
+    if (!type) {
       params = g_new0 (GstFFMpegEncClassParams, 1);
       params->in_plugin = in_plugin;
       params->srccaps = gst_caps_ref (srccaps);
@@ -1200,6 +1197,7 @@ gst_ffmpegenc_register (GstPlugin * plugin)
         };
         g_type_add_interface_static (type, GST_TYPE_PRESET, &preset_info);
       }
+    }
 
     if (!gst_element_register (plugin, type_name, GST_RANK_NONE, type)) {
       g_free (type_name);

ext/ffmpeg/gstffmpegmux.c

@@ -835,17 +835,6 @@ gst_ffmpegmux_register (GstPlugin * plugin)
       p++;
     }
 
-    /* if it's already registered, drop it */
-    if (g_type_from_name (type_name)) {
-      g_free (type_name);
-      gst_caps_unref (srccaps);
-      if (audiosinkcaps)
-        gst_caps_unref (audiosinkcaps);
-      if (videosinkcaps)
-        gst_caps_unref (videosinkcaps);
-      goto next;
-    }
-
     /* fix up allowed caps for some muxers */
     if (strcmp (in_plugin->name, "flv") == 0) {
       const gint rates[] = { 44100, 22050, 11025 };
@@ -859,6 +848,9 @@ gst_ffmpegmux_register (GstPlugin * plugin)
           gst_caps_from_string ("video/x-raw-rgb, bpp=(int)24, depth=(int)24");
     }
 
+    type = g_type_from_name (type_name);
+
+    if (!type) {
       /* create a cache for these properties */
       params = g_new0 (GstFFMpegMuxClassParams, 1);
       params->in_plugin = in_plugin;
@@ -871,6 +863,8 @@ gst_ffmpegmux_register (GstPlugin * plugin)
       g_type_set_qdata (type, GST_FFMUX_PARAMS_QDATA, (gpointer) params);
       g_type_add_interface_static (type, GST_TYPE_TAG_SETTER, &tag_setter_info);
 
+    }
+
     if (!gst_element_register (plugin, type_name, GST_RANK_NONE, type)) {
       g_free (type_name);
       gst_caps_unref (srccaps);