tag: xmp: Make xmp lib aware for the different tag types

Makes the xmp helper lib aware that the tags can be simple,
sequences or bags (there is still struct and alt, but those
aren't handled yet). Adding this info makes serialization
and deserialization more consistent.

1 files changed, 131 insertions, 65 deletions

diff --git a/gst-libs/gst/tag/gstxmptag.c b/gst-libs/gst/tag/gstxmptag.c
index fda9df2d6..38b5533ad 100644
--- a/gst-libs/gst/tag/gstxmptag.c
+++ b/gst-libs/gst/tag/gstxmptag.c
@@ -43,6 +43,8 @@
 #include <time.h>
 #include <ctype.h>
 
+typedef struct _XmpTag XmpTag;
+
 /*
  * Serializes a GValue into a string.
  */
@@ -50,24 +52,55 @@ typedef gchar *(*XmpSerializationFunc) (const GValue * value);
 
 /*
  * Deserializes @str that is the gstreamer tag @gst_tag represented in
- * XMP as the @xmp_tag and adds the result to the @taglist.
+ * XMP as the @xmp_tag_value and adds the result to the @taglist.
  *
  * @pending_tags is passed so that compound xmp tags can search for its
  * complements on the list and use them. Note that used complements should
  * be freed and removed from the list.
  * The list is of PendingXmpTag
  */
-typedef void (*XmpDeserializationFunc) (GstTagList * taglist,
-    const gchar * gst_tag, const gchar * xmp_tag,
+typedef void (*XmpDeserializationFunc) (XmpTag * xmptag, GstTagList * taglist,
+    const gchar * gst_tag, const gchar * xmp_tag_value,
     const gchar * str, GSList ** pending_tags);
 
+
+#define GST_XMP_TAG_TYPE_SIMPLE 0
+#define GST_XMP_TAG_TYPE_BAG    1
+#define GST_XMP_TAG_TYPE_SEQ    2
 struct _XmpTag
 {
   const gchar *tag_name;
+  gint type;
+
   XmpSerializationFunc serialize;
   XmpDeserializationFunc deserialize;
 };
-typedef struct _XmpTag XmpTag;
+
+static GstTagMergeMode
+xmp_tag_get_merge_mode (XmpTag * xmptag)
+{
+  switch (xmptag->type) {
+    case GST_XMP_TAG_TYPE_BAG:
+    case GST_XMP_TAG_TYPE_SEQ:
+      return GST_TAG_MERGE_APPEND;
+    case GST_XMP_TAG_TYPE_SIMPLE:
+    default:
+      return GST_TAG_MERGE_KEEP;
+  }
+}
+
+static const gchar *
+xmp_tag_get_type_name (XmpTag * xmptag)
+{
+  switch (xmptag->type) {
+    case GST_XMP_TAG_TYPE_SEQ:
+      return "rdf:Seq";
+    default:
+      g_assert_not_reached ();
+    case GST_XMP_TAG_TYPE_BAG:
+      return "rdf:Bag";
+  }
+}
 
 struct _PendingXmpTag
 {
@@ -77,6 +110,7 @@ struct _PendingXmpTag
 };
 typedef struct _PendingXmpTag PendingXmpTag;
 
+
 /*
  * A schema is a mapping of strings (the tag name in gstreamer) to a list of
  * tags in xmp (XmpTag). We need a list because some tags are split into 2
@@ -133,7 +167,7 @@ _gst_xmp_schema_add_mapping (GstXmpSchema * schema, const gchar * gst_tag,
 
 static void
 _gst_xmp_schema_add_simple_mapping (GstXmpSchema * schema,
-    const gchar * gst_tag, const gchar * xmp_tag,
+    const gchar * gst_tag, const gchar * xmp_tag, gint xmp_type,
     XmpSerializationFunc serialization_func,
     XmpDeserializationFunc deserialization_func)
 {
@@ -142,6 +176,7 @@ _gst_xmp_schema_add_simple_mapping (GstXmpSchema * schema,
 
   xmpinfo = g_slice_new (XmpTag);
   xmpinfo->tag_name = xmp_tag;
+  xmpinfo->type = xmp_type;
   xmpinfo->serialize = serialization_func;
   xmpinfo->deserialize = deserialization_func;
 
@@ -279,8 +314,8 @@ serialize_exif_longitude (const GValue * value)
 }
 
 static void
-deserialize_exif_gps_coordinate (GstTagList * taglist, const gchar * gst_tag,
-    const gchar * str, gchar pos, gchar neg)
+deserialize_exif_gps_coordinate (XmpTag * xmptag, GstTagList * taglist,
+    const gchar * gst_tag, const gchar * str, gchar pos, gchar neg)
 {
   gdouble value = 0;
   gint d = 0, m = 0, s = 0;
@@ -342,7 +377,8 @@ end:
     goto error;
   }
 
-  gst_tag_list_add (taglist, GST_TAG_MERGE_REPLACE, gst_tag, value, NULL);
+  gst_tag_list_add (taglist, xmp_tag_get_merge_mode (xmptag), gst_tag, value,
+      NULL);
   return;
 
 error:
@@ -350,17 +386,19 @@ error:
 }
 
 static void
-deserialize_exif_latitude (GstTagList * taglist, const gchar * gst_tag,
-    const gchar * xmp_tag, const gchar * str, GSList ** pending_tags)
+deserialize_exif_latitude (XmpTag * xmptag, GstTagList * taglist,
+    const gchar * gst_tag, const gchar * xmp_tag, const gchar * str,
+    GSList ** pending_tags)
 {
-  deserialize_exif_gps_coordinate (taglist, gst_tag, str, 'N', 'S');
+  deserialize_exif_gps_coordinate (xmptag, taglist, gst_tag, str, 'N', 'S');
 }
 
 static void
-deserialize_exif_longitude (GstTagList * taglist, const gchar * gst_tag,
-    const gchar * xmp_tag, const gchar * str, GSList ** pending_tags)
+deserialize_exif_longitude (XmpTag * xmptag, GstTagList * taglist,
+    const gchar * gst_tag, const gchar * xmp_tag, const gchar * str,
+    GSList ** pending_tags)
 {
-  deserialize_exif_gps_coordinate (taglist, gst_tag, str, 'E', 'W');
+  deserialize_exif_gps_coordinate (xmptag, taglist, gst_tag, str, 'E', 'W');
 }
 
 static gchar *
@@ -390,8 +428,9 @@ serialize_exif_altituderef (const GValue * value)
 }
 
 static void
-deserialize_exif_altitude (GstTagList * taglist, const gchar * gst_tag,
-    const gchar * xmp_tag, const gchar * str, GSList ** pending_tags)
+deserialize_exif_altitude (XmpTag * xmptag, GstTagList * taglist,
+    const gchar * gst_tag, const gchar * xmp_tag, const gchar * str,
+    GSList ** pending_tags)
 {
   const gchar *altitude_str = NULL;
   const gchar *altituderef_str = NULL;
@@ -458,7 +497,7 @@ deserialize_exif_altitude (GstTagList * taglist, const gchar * gst_tag,
   }
 
   /* add to the taglist */
-  gst_tag_list_add (taglist, GST_TAG_MERGE_REPLACE,
+  gst_tag_list_add (taglist, xmp_tag_get_merge_mode (xmptag),
       GST_TAG_GEO_LOCATION_ELEVATION, value, NULL);
 
   /* clean up entry */
@@ -482,8 +521,9 @@ serialize_exif_gps_speedref (const GValue * value)
 }
 
 static void
-deserialize_exif_gps_speed (GstTagList * taglist, const gchar * gst_tag,
-    const gchar * xmp_tag, const gchar * str, GSList ** pending_tags)
+deserialize_exif_gps_speed (XmpTag * xmptag, GstTagList * taglist,
+    const gchar * gst_tag, const gchar * xmp_tag, const gchar * str,
+    GSList ** pending_tags)
 {
   const gchar *speed_str = NULL;
   const gchar *speedref_str = NULL;
@@ -552,7 +592,7 @@ deserialize_exif_gps_speed (GstTagList * taglist, const gchar * gst_tag,
   }
 
   /* add to the taglist */
-  gst_tag_list_add (taglist, GST_TAG_MERGE_REPLACE,
+  gst_tag_list_add (taglist, xmp_tag_get_merge_mode (xmptag),
       GST_TAG_GEO_LOCATION_MOVEMENT_SPEED, value, NULL);
 
   /* clean up entry */
@@ -575,9 +615,10 @@ serialize_exif_gps_directionref (const GValue * value)
 }
 
 static void
-deserialize_exif_gps_direction (GstTagList * taglist, const gchar * gst_tag,
-    const gchar * xmp_tag, const gchar * str, GSList ** pending_tags,
-    const gchar * direction_tag, const gchar * directionref_tag)
+deserialize_exif_gps_direction (XmpTag * xmptag, GstTagList * taglist,
+    const gchar * gst_tag, const gchar * xmp_tag, const gchar * str,
+    GSList ** pending_tags, const gchar * direction_tag,
+    const gchar * directionref_tag)
 {
   const gchar *dir_str = NULL;
   const gchar *dirref_str = NULL;
@@ -645,7 +686,8 @@ deserialize_exif_gps_direction (GstTagList * taglist, const gchar * gst_tag,
   }
 
   /* add to the taglist */
-  gst_tag_list_add (taglist, GST_TAG_MERGE_REPLACE, gst_tag, value, NULL);
+  gst_tag_list_add (taglist, xmp_tag_get_merge_mode (xmptag), gst_tag, value,
+      NULL);
 
   /* clean up entry */
   g_free (ptag->str);
@@ -654,24 +696,27 @@ deserialize_exif_gps_direction (GstTagList * taglist, const gchar * gst_tag,
 }
 
 static void
-deserialize_exif_gps_track (GstTagList * taglist, const gchar * gst_tag,
-    const gchar * xmp_tag, const gchar * str, GSList ** pending_tags)
+deserialize_exif_gps_track (XmpTag * xmptag, GstTagList * taglist,
+    const gchar * gst_tag, const gchar * xmp_tag, const gchar * str,
+    GSList ** pending_tags)
 {
-  deserialize_exif_gps_direction (taglist, gst_tag, xmp_tag, str, pending_tags,
-      "exif:GPSTrack", "exif:GPSTrackRef");
+  deserialize_exif_gps_direction (xmptag, taglist, gst_tag, xmp_tag, str,
+      pending_tags, "exif:GPSTrack", "exif:GPSTrackRef");
 }
 
 static void
-deserialize_exif_gps_img_direction (GstTagList * taglist, const gchar * gst_tag,
-    const gchar * xmp_tag, const gchar * str, GSList ** pending_tags)
+deserialize_exif_gps_img_direction (XmpTag * xmptag, GstTagList * taglist,
+    const gchar * gst_tag, const gchar * xmp_tag, const gchar * str,
+    GSList ** pending_tags)
 {
-  deserialize_exif_gps_direction (taglist, gst_tag, xmp_tag, str, pending_tags,
-      "exif:GPSImgDirection", "exif:GPSImgDirectionRef");
+  deserialize_exif_gps_direction (xmptag, taglist, gst_tag, xmp_tag, str,
+      pending_tags, "exif:GPSImgDirection", "exif:GPSImgDirectionRef");
 }
 
 static void
-deserialize_xmp_rating (GstTagList * taglist, const gchar * gst_tag,
-    const gchar * xmp_tag, const gchar * str, GSList ** pending_tags)
+deserialize_xmp_rating (XmpTag * xmptag, GstTagList * taglist,
+    const gchar * gst_tag, const gchar * xmp_tag, const gchar * str,
+    GSList ** pending_tags)
 {
   guint value;
 
@@ -686,7 +731,8 @@ deserialize_xmp_rating (GstTagList * taglist, const gchar * gst_tag,
     return;
   }
 
-  gst_tag_list_add (taglist, GST_TAG_MERGE_REPLACE, gst_tag, value, NULL);
+  gst_tag_list_add (taglist, xmp_tag_get_merge_mode (xmptag), gst_tag, value,
+      NULL);
 }
 
 static gchar *
@@ -709,8 +755,9 @@ serialize_tiff_orientation (const GValue * value)
 }
 
 static void
-deserialize_tiff_orientation (GstTagList * taglist, const gchar * gst_tag,
-    const gchar * xmp_tag, const gchar * str, GSList ** pending_tags)
+deserialize_tiff_orientation (XmpTag * xmptag, GstTagList * taglist,
+    const gchar * gst_tag, const gchar * xmp_tag, const gchar * str,
+    GSList ** pending_tags)
 {
   guint value;
   const gchar *orientation = NULL;
@@ -729,7 +776,8 @@ deserialize_tiff_orientation (GstTagList * taglist, const gchar * gst_tag,
   orientation = gst_tag_image_orientation_from_exif_value (value);
   if (orientation == NULL)
     return;
-  gst_tag_list_add (taglist, GST_TAG_MERGE_REPLACE, gst_tag, orientation, NULL);
+  gst_tag_list_add (taglist, xmp_tag_get_merge_mode (xmptag), gst_tag,
+      orientation, NULL);
 }
 
 
@@ -751,47 +799,49 @@ _init_xmp_tag_map ()
    */
   schema = gst_xmp_schema_new ();
   _gst_xmp_schema_add_simple_mapping (schema, GST_TAG_ARTIST,
-      "dc:creator", NULL, NULL);
+      "dc:creator", GST_XMP_TAG_TYPE_SEQ, NULL, NULL);
   _gst_xmp_schema_add_simple_mapping (schema, GST_TAG_COPYRIGHT,
-      "dc:rights", NULL, NULL);
+      "dc:rights", GST_XMP_TAG_TYPE_SIMPLE, NULL, NULL);
   _gst_xmp_schema_add_simple_mapping (schema, GST_TAG_DATE, "dc:date",
-      NULL, NULL);
+      GST_XMP_TAG_TYPE_SEQ, NULL, NULL);
   _gst_xmp_schema_add_simple_mapping (schema, GST_TAG_DESCRIPTION,
-      "dc:description", NULL, NULL);
+      "dc:description", GST_XMP_TAG_TYPE_SIMPLE, NULL, NULL);
   _gst_xmp_schema_add_simple_mapping (schema, GST_TAG_KEYWORDS,
-      "dc:subject", NULL, NULL);
+      "dc:subject", GST_XMP_TAG_TYPE_BAG, NULL, NULL);
   _gst_xmp_schema_add_simple_mapping (schema, GST_TAG_TITLE, "dc:title",
-      NULL, NULL);
+      GST_XMP_TAG_TYPE_SIMPLE, NULL, NULL);
   /* FIXME: we probably want GST_TAG_{,AUDIO_,VIDEO_}MIME_TYPE */
   _gst_xmp_schema_add_simple_mapping (schema, GST_TAG_VIDEO_CODEC,
-      "dc:format", NULL, NULL);
+      "dc:format", GST_XMP_TAG_TYPE_SIMPLE, NULL, NULL);
   _gst_xmp_add_schema ("dc", schema);
 
   /* xap (xmp) schema */
   schema = gst_xmp_schema_new ();
   _gst_xmp_schema_add_simple_mapping (schema, GST_TAG_USER_RATING,
-      "xmp:Rating", NULL, deserialize_xmp_rating);
+      "xmp:Rating", GST_XMP_TAG_TYPE_SIMPLE, NULL, deserialize_xmp_rating);
   _gst_xmp_add_schema ("xmp", schema);
 
   /* tiff */
   _gst_xmp_schema_add_simple_mapping (schema,
-      GST_TAG_DEVICE_MANUFACTURER, "tiff:Make", NULL, NULL);
+      GST_TAG_DEVICE_MANUFACTURER, "tiff:Make", GST_XMP_TAG_TYPE_SIMPLE, NULL,
+      NULL);
   _gst_xmp_schema_add_simple_mapping (schema, GST_TAG_DEVICE_MODEL,
-      "tiff:Model", NULL, NULL);
+      "tiff:Model", GST_XMP_TAG_TYPE_SIMPLE, NULL, NULL);
   _gst_xmp_schema_add_simple_mapping (schema, GST_TAG_IMAGE_ORIENTATION,
-      "tiff:Orientation", serialize_tiff_orientation,
+      "tiff:Orientation", GST_XMP_TAG_TYPE_SIMPLE, serialize_tiff_orientation,
       deserialize_tiff_orientation);
   _gst_xmp_add_schema ("tiff", schema);
 
   /* exif schema */
   _gst_xmp_schema_add_simple_mapping (schema, GST_TAG_DATE_TIME,
-      "exif:DateTimeOriginal", NULL, NULL);
+      "exif:DateTimeOriginal", GST_XMP_TAG_TYPE_SIMPLE, NULL, NULL);
   _gst_xmp_schema_add_simple_mapping (schema,
       GST_TAG_GEO_LOCATION_LATITUDE, "exif:GPSLatitude",
-      serialize_exif_latitude, deserialize_exif_latitude);
-  _gst_xmp_schema_add_simple_mapping (schema,
-      GST_TAG_GEO_LOCATION_LONGITUDE, "exif:GPSLongitude",
-      serialize_exif_longitude, deserialize_exif_longitude);
+      GST_XMP_TAG_TYPE_SIMPLE, serialize_exif_latitude,
+      deserialize_exif_latitude);
+  _gst_xmp_schema_add_simple_mapping (schema, GST_TAG_GEO_LOCATION_LONGITUDE,
+      "exif:GPSLongitude", GST_XMP_TAG_TYPE_SIMPLE, serialize_exif_longitude,
+      deserialize_exif_longitude);
 
   /* compound exif tags */
   array = g_ptr_array_sized_new (2);
@@ -799,11 +849,13 @@ _init_xmp_tag_map ()
   xmpinfo->tag_name = "exif:GPSAltitude";
   xmpinfo->serialize = serialize_exif_altitude;
   xmpinfo->deserialize = deserialize_exif_altitude;
+  xmpinfo->type = GST_XMP_TAG_TYPE_SIMPLE;
   g_ptr_array_add (array, xmpinfo);
   xmpinfo = g_slice_new (XmpTag);
   xmpinfo->tag_name = "exif:GPSAltitudeRef";
   xmpinfo->serialize = serialize_exif_altituderef;
   xmpinfo->deserialize = deserialize_exif_altitude;
+  xmpinfo->type = GST_XMP_TAG_TYPE_SIMPLE;
   g_ptr_array_add (array, xmpinfo);
   _gst_xmp_schema_add_mapping (schema, GST_TAG_GEO_LOCATION_ELEVATION, array);
 
@@ -812,11 +864,13 @@ _init_xmp_tag_map ()
   xmpinfo->tag_name = "exif:GPSSpeed";
   xmpinfo->serialize = serialize_exif_gps_speed;
   xmpinfo->deserialize = deserialize_exif_gps_speed;
+  xmpinfo->type = GST_XMP_TAG_TYPE_SIMPLE;
   g_ptr_array_add (array, xmpinfo);
   xmpinfo = g_slice_new (XmpTag);
   xmpinfo->tag_name = "exif:GPSSpeedRef";
   xmpinfo->serialize = serialize_exif_gps_speedref;
   xmpinfo->deserialize = deserialize_exif_gps_speed;
+  xmpinfo->type = GST_XMP_TAG_TYPE_SIMPLE;
   g_ptr_array_add (array, xmpinfo);
   _gst_xmp_schema_add_mapping (schema,
       GST_TAG_GEO_LOCATION_MOVEMENT_SPEED, array);
@@ -826,11 +880,13 @@ _init_xmp_tag_map ()
   xmpinfo->tag_name = "exif:GPSTrack";
   xmpinfo->serialize = serialize_exif_gps_direction;
   xmpinfo->deserialize = deserialize_exif_gps_track;
+  xmpinfo->type = GST_XMP_TAG_TYPE_SIMPLE;
   g_ptr_array_add (array, xmpinfo);
   xmpinfo = g_slice_new (XmpTag);
   xmpinfo->tag_name = "exif:GPSTrackRef";
   xmpinfo->serialize = serialize_exif_gps_directionref;
   xmpinfo->deserialize = deserialize_exif_gps_track;
+  xmpinfo->type = GST_XMP_TAG_TYPE_SIMPLE;
   g_ptr_array_add (array, xmpinfo);
   _gst_xmp_schema_add_mapping (schema,
       GST_TAG_GEO_LOCATION_MOVEMENT_DIRECTION, array);
@@ -840,11 +896,13 @@ _init_xmp_tag_map ()
   xmpinfo->tag_name = "exif:GPSImgDirection";
   xmpinfo->serialize = serialize_exif_gps_direction;
   xmpinfo->deserialize = deserialize_exif_gps_img_direction;
+  xmpinfo->type = GST_XMP_TAG_TYPE_SIMPLE;
   g_ptr_array_add (array, xmpinfo);
   xmpinfo = g_slice_new (XmpTag);
   xmpinfo->tag_name = "exif:GPSImgDirectionRef";
   xmpinfo->serialize = serialize_exif_gps_directionref;
   xmpinfo->deserialize = deserialize_exif_gps_img_direction;
+  xmpinfo->type = GST_XMP_TAG_TYPE_SIMPLE;
   g_ptr_array_add (array, xmpinfo);
   _gst_xmp_schema_add_mapping (schema,
       GST_TAG_GEO_LOCATION_CAPTURE_DIRECTION, array);
@@ -852,14 +910,16 @@ _init_xmp_tag_map ()
 
   /* photoshop schema */
   _gst_xmp_schema_add_simple_mapping (schema,
-      GST_TAG_GEO_LOCATION_COUNTRY, "photoshop:Country", NULL, NULL);
+      GST_TAG_GEO_LOCATION_COUNTRY, "photoshop:Country",
+      GST_XMP_TAG_TYPE_SIMPLE, NULL, NULL);
   _gst_xmp_schema_add_simple_mapping (schema, GST_TAG_GEO_LOCATION_CITY,
-      "photoshop:City", NULL, NULL);
+      "photoshop:City", GST_XMP_TAG_TYPE_SIMPLE, NULL, NULL);
   _gst_xmp_add_schema ("photoshop", schema);
 
   /* iptc4xmpcore schema */
   _gst_xmp_schema_add_simple_mapping (schema,
-      GST_TAG_GEO_LOCATION_SUBLOCATION, "Iptc4xmpCore:Location", NULL, NULL);
+      GST_TAG_GEO_LOCATION_SUBLOCATION, "Iptc4xmpCore:Location",
+      GST_XMP_TAG_TYPE_SIMPLE, NULL, NULL);
   _gst_xmp_add_schema ("Iptc4xmpCore", schema);
 
   return NULL;
@@ -912,18 +972,20 @@ read_one_tag (GstTagList * list, const gchar * tag, XmpTag * xmptag,
     const gchar * v, GSList ** pending_tags)
 {
   GType tag_type;
+  GstTagMergeMode merge_mode;
 
   if (xmptag && xmptag->deserialize) {
-    xmptag->deserialize (list, tag, xmptag->tag_name, v, pending_tags);
+    xmptag->deserialize (xmptag, list, tag, xmptag->tag_name, v, pending_tags);
     return;
   }
 
+  merge_mode = xmp_tag_get_merge_mode (xmptag);
   tag_type = gst_tag_get_type (tag);
 
   /* add gstreamer tag depending on type */
   switch (tag_type) {
     case G_TYPE_STRING:{
-      gst_tag_list_add (list, GST_TAG_MERGE_APPEND, tag, v, NULL);
+      gst_tag_list_add (list, merge_mode, tag, v, NULL);
       break;
     }
     default:
@@ -1020,7 +1082,7 @@ read_one_tag (GstTagList * list, const gchar * tag, XmpTag * xmptag,
         }
 
         if (datetime) {
-          gst_tag_list_add (list, GST_TAG_MERGE_REPLACE, tag, datetime, NULL);
+          gst_tag_list_add (list, merge_mode, tag, datetime, NULL);
           gst_date_time_unref (datetime);
         }
 
@@ -1045,7 +1107,7 @@ read_one_tag (GstTagList * list, const gchar * tag, XmpTag * xmptag,
            date = g_date_new ();
            g_date_set_parse (date, v);
            if (g_date_valid (date)) {
-           gst_tag_list_add (list, GST_TAG_MERGE_REPLACE, tag,
+           gst_tag_list_add (list, merge_mode, tag,
            date, NULL);
            } else {
            GST_WARNING ("unparsable date: '%s'", v);
@@ -1054,7 +1116,7 @@ read_one_tag (GstTagList * list, const gchar * tag, XmpTag * xmptag,
         /* poor mans straw */
         sscanf (v, "%04d-%02d-%02dT", &y, &m, &d);
         date = g_date_new_dmy (d, m, y);
-        gst_tag_list_add (list, GST_TAG_MERGE_REPLACE, tag, date, NULL);
+        gst_tag_list_add (list, merge_mode, tag, date, NULL);
         g_date_free (date);
       } else {
         GST_WARNING ("unhandled type for %s from xmp", tag);
@@ -1404,7 +1466,7 @@ write_one_tag (const GstTagList * list, const gchar * tag, gpointer user_data)
     string_open_tag (data, xmp_tag->tag_name);
 
     /* fast path for single valued tag */
-    if (ct == 1) {
+    if (ct == 1 || xmp_tag->type == GST_XMP_TAG_TYPE_SIMPLE) {
       if (xmp_tag->serialize) {
         s = xmp_tag->serialize (gst_tag_list_get_value_index (list, tag, 0));
       } else {
@@ -1418,7 +1480,11 @@ write_one_tag (const GstTagList * list, const gchar * tag, gpointer user_data)
         GST_WARNING ("unhandled type for %s to xmp", tag);
       }
     } else {
-      string_open_tag (data, "rdf:Bag");
+      const gchar *typename;
+
+      typename = xmp_tag_get_type_name (xmp_tag);
+
+      string_open_tag (data, typename);
       for (i = 0; i < ct; i++) {
         GST_DEBUG ("mapping %s[%u/%u] to xmp", tag, i, ct);
         if (xmp_tag->serialize) {
@@ -1436,7 +1502,7 @@ write_one_tag (const GstTagList * list, const gchar * tag, gpointer user_data)
           GST_WARNING ("unhandled type for %s to xmp", tag);
         }
       }
-      string_close_tag (data, "rdf:Bag");
+      string_close_tag (data, typename);
     }
 
     string_close_tag (data, xmp_tag->tag_name);