--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gst_plugins_base/gst-libs/gst/pbutils/missing-plugins.c	Thu Dec 17 08:53:32 2009 +0200
@@ -0,0 +1,852 @@
+/* GStreamer base utils library missing plugins support
+ * Copyright (C) 2006 Tim-Philipp Müller <tim centricular net>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+/**
+ * SECTION:gstpbutilsmissingplugins
+ * @short_description: Create, recognise and parse missing-plugins messages
+ *
+ * <refsect2>
+ * <para>
+ * Functions to create, recognise and parse missing-plugins messages for
+ * applications and elements.
+ * </para>
+ * <para>
+ * Missing-plugin messages are posted on the bus by elements like decodebin
+ * or playbin if they can't find an appropriate source element or decoder
+ * element. The application can use these messages for two things:
+ * <itemizedlist>
+ *   <listitem><para>
+ *     concise error/problem reporting to the user mentioning what exactly
+ *     is missing, see gst_missing_plugin_message_get_description()
+ *   </para></listitem>
+ *   <listitem><para>
+ *     initiate installation of missing plugins, see
+ *     gst_missing_plugin_message_get_installer_detail() and
+ *     gst_install_plugins_async()
+ *   </para></listitem>
+ * </itemizedlist>
+ * </para>
+ * <para>
+ * Applications may also create missing-plugin messages themselves to install
+ * required elements that are missing, using the install mechanism mentioned
+ * above.
+ * </para>
+ * </refsect2>
+ */
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#ifdef HAVE_SYS_TYPES_H
+# include <sys/types.h>
+#endif
+#ifdef HAVE_UNISTD_H
+# include <unistd.h>            /* getpid on UNIX */
+#endif
+#ifdef HAVE_PROCESS_H
+# include <process.h>           /* getpid on win32 */
+#endif
+
+#ifdef __SYMBIAN32__
+#include <gst_global.h>
+#endif
+
+#include "gst/gst-i18n-plugin.h"
+
+#include "pbutils.h"
+
+#include <string.h>
+
+#define GST_DETAIL_STRING_MARKER "gstreamer"
+
+typedef enum
+{
+  GST_MISSING_TYPE_UNKNOWN = 0,
+  GST_MISSING_TYPE_URISOURCE,
+  GST_MISSING_TYPE_URISINK,
+  GST_MISSING_TYPE_ELEMENT,
+  GST_MISSING_TYPE_DECODER,
+  GST_MISSING_TYPE_ENCODER
+} GstMissingType;
+
+static const struct
+{
+  GstMissingType type;
+  const gchar type_string[12];
+} missing_type_mapping[] = {
+  {
+  GST_MISSING_TYPE_URISOURCE, "urisource"}, {
+  GST_MISSING_TYPE_URISINK, "urisink"}, {
+  GST_MISSING_TYPE_ELEMENT, "element"}, {
+  GST_MISSING_TYPE_DECODER, "decoder"}, {
+  GST_MISSING_TYPE_ENCODER, "encoder"}
+};
+
+static GstMissingType
+missing_structure_get_type (const GstStructure * s)
+{
+  const gchar *type;
+  guint i;
+
+  type = gst_structure_get_string (s, "type");
+  g_return_val_if_fail (type != NULL, GST_MISSING_TYPE_UNKNOWN);
+
+  for (i = 0; i < G_N_ELEMENTS (missing_type_mapping); ++i) {
+    if (strcmp (missing_type_mapping[i].type_string, type) == 0)
+      return missing_type_mapping[i].type;
+  }
+
+  return GST_MISSING_TYPE_UNKNOWN;
+}
+
+static GstCaps *
+copy_and_clean_caps (const GstCaps * caps)
+{
+  GstStructure *s;
+  GstCaps *ret;
+
+  ret = gst_caps_copy (caps);
+
+  /* make caps easier to interpret, remove common fields that are likely
+   * to be irrelevant for determining the right plugin (ie. mostly fields
+   * where template caps usually have the standard MIN - MAX range as value) */
+  s = gst_caps_get_structure (ret, 0);
+  gst_structure_remove_field (s, "codec_data");
+  gst_structure_remove_field (s, "palette_data");
+  gst_structure_remove_field (s, "pixel-aspect-ratio");
+  gst_structure_remove_field (s, "framerate");
+  gst_structure_remove_field (s, "leaf_size");
+  gst_structure_remove_field (s, "packet_size");
+  /* decoders/encoders almost always handle the usual width/height/channel/rate
+   * range (and if we don't remove this then the app will have a much harder
+   * time blacklisting formats it has unsuccessfully tried to install before) */
+  gst_structure_remove_field (s, "width");
+  gst_structure_remove_field (s, "height");
+  gst_structure_remove_field (s, "channels");
+  gst_structure_remove_field (s, "rate");
+  /* rtp fields */
+  gst_structure_remove_field (s, "config");
+  gst_structure_remove_field (s, "clock-rate");
+  gst_structure_remove_field (s, "clock-base");
+  gst_structure_remove_field (s, "maxps");
+  gst_structure_remove_field (s, "seqnum-base");
+  gst_structure_remove_field (s, "npt-start");
+  gst_structure_remove_field (s, "npt-stop");
+  gst_structure_remove_field (s, "play-speed");
+  gst_structure_remove_field (s, "play-scale");
+
+  return ret;
+}
+
+/**
+ * gst_missing_uri_source_message_new:
+ * @element: the #GstElement posting the message
+ * @protocol: the URI protocol the missing source needs to implement,
+ *            e.g. "http" or "mms"
+ *
+ * Creates a missing-plugin message for @element to notify the application
+ * that a source element for a particular URI protocol is missing. This
+ * function is mainly for use in plugins.
+ *
+ * Returns: a new #GstMessage, or NULL on error
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+GstMessage *
+gst_missing_uri_source_message_new (GstElement * element,
+    const gchar * protocol)
+{
+  GstStructure *s;
+  gchar *description;
+
+  g_return_val_if_fail (element != NULL, NULL);
+  g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
+  g_return_val_if_fail (protocol != NULL, NULL);
+
+  description = gst_pb_utils_get_source_description (protocol);
+
+  s = gst_structure_new ("missing-plugin", "type", G_TYPE_STRING,
+      "urisource", "detail", G_TYPE_STRING, protocol, "name", G_TYPE_STRING,
+      description, NULL);
+
+  g_free (description);
+  return gst_message_new_element (GST_OBJECT_CAST (element), s);
+}
+
+/**
+ * gst_missing_uri_sink_message_new:
+ * @element: the #GstElement posting the message
+ * @protocol: the URI protocol the missing sink needs to implement,
+ *            e.g. "http" or "smb"
+ *
+ * Creates a missing-plugin message for @element to notify the application
+ * that a sink element for a particular URI protocol is missing. This
+ * function is mainly for use in plugins.
+ *
+ * Returns: a new #GstMessage, or NULL on error
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+GstMessage *
+gst_missing_uri_sink_message_new (GstElement * element, const gchar * protocol)
+{
+  GstStructure *s;
+  gchar *description;
+
+  g_return_val_if_fail (element != NULL, NULL);
+  g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
+  g_return_val_if_fail (protocol != NULL, NULL);
+
+  description = gst_pb_utils_get_sink_description (protocol);
+
+  s = gst_structure_new ("missing-plugin", "type", G_TYPE_STRING,
+      "urisink", "detail", G_TYPE_STRING, protocol, "name", G_TYPE_STRING,
+      description, NULL);
+
+  g_free (description);
+  return gst_message_new_element (GST_OBJECT_CAST (element), s);
+}
+
+/**
+ * gst_missing_element_message_new:
+ * @element: the #GstElement posting the message
+ * @factory_name: the name of the missing element (element factory),
+ *            e.g. "videoscale" or "cdparanoiasrc"
+ *
+ * Creates a missing-plugin message for @element to notify the application
+ * that a certain required element is missing. This function is mainly for
+ * use in plugins.
+ *
+ * Returns: a new #GstMessage, or NULL on error
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+GstMessage *
+gst_missing_element_message_new (GstElement * element,
+    const gchar * factory_name)
+{
+  GstStructure *s;
+  gchar *description;
+
+  g_return_val_if_fail (element != NULL, NULL);
+  g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
+  g_return_val_if_fail (factory_name != NULL, NULL);
+
+  description = gst_pb_utils_get_element_description (factory_name);
+
+  s = gst_structure_new ("missing-plugin", "type", G_TYPE_STRING,
+      "element", "detail", G_TYPE_STRING, factory_name, "name", G_TYPE_STRING,
+      description, NULL);
+
+  g_free (description);
+  return gst_message_new_element (GST_OBJECT_CAST (element), s);
+}
+
+/**
+ * gst_missing_decoder_message_new:
+ * @element: the #GstElement posting the message
+ * @decode_caps: the (fixed) caps for which a decoder element is needed
+ *
+ * Creates a missing-plugin message for @element to notify the application
+ * that a decoder element for a particular set of (fixed) caps is missing.
+ * This function is mainly for use in plugins.
+ *
+ * Returns: a new #GstMessage, or NULL on error
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+GstMessage *
+gst_missing_decoder_message_new (GstElement * element,
+    const GstCaps * decode_caps)
+{
+  GstStructure *s;
+  GstCaps *caps;
+  gchar *description;
+
+  g_return_val_if_fail (element != NULL, NULL);
+  g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
+  g_return_val_if_fail (decode_caps != NULL, NULL);
+  g_return_val_if_fail (GST_IS_CAPS (decode_caps), NULL);
+  g_return_val_if_fail (!gst_caps_is_any (decode_caps), NULL);
+  g_return_val_if_fail (!gst_caps_is_empty (decode_caps), NULL);
+  g_return_val_if_fail (gst_caps_is_fixed (decode_caps), NULL);
+
+  description = gst_pb_utils_get_decoder_description (decode_caps);
+  caps = copy_and_clean_caps (decode_caps);
+
+  s = gst_structure_new ("missing-plugin", "type", G_TYPE_STRING,
+      "decoder", "detail", GST_TYPE_CAPS, caps, "name", G_TYPE_STRING,
+      description, NULL);
+
+  gst_caps_unref (caps);
+  g_free (description);
+
+  return gst_message_new_element (GST_OBJECT_CAST (element), s);
+}
+
+/**
+ * gst_missing_encoder_message_new:
+ * @element: the #GstElement posting the message
+ * @encode_caps: the (fixed) caps for which an encoder element is needed
+ *
+ * Creates a missing-plugin message for @element to notify the application
+ * that an encoder element for a particular set of (fixed) caps is missing.
+ * This function is mainly for use in plugins.
+ *
+ * Returns: a new #GstMessage, or NULL on error
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+GstMessage *
+gst_missing_encoder_message_new (GstElement * element,
+    const GstCaps * encode_caps)
+{
+  GstStructure *s;
+  GstCaps *caps;
+  gchar *description;
+
+  g_return_val_if_fail (element != NULL, NULL);
+  g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
+  g_return_val_if_fail (encode_caps != NULL, NULL);
+  g_return_val_if_fail (GST_IS_CAPS (encode_caps), NULL);
+  g_return_val_if_fail (!gst_caps_is_any (encode_caps), NULL);
+  g_return_val_if_fail (!gst_caps_is_empty (encode_caps), NULL);
+  g_return_val_if_fail (gst_caps_is_fixed (encode_caps), NULL);
+
+  description = gst_pb_utils_get_encoder_description (encode_caps);
+  caps = copy_and_clean_caps (encode_caps);
+
+  s = gst_structure_new ("missing-plugin", "type", G_TYPE_STRING,
+      "encoder", "detail", GST_TYPE_CAPS, caps, "name", G_TYPE_STRING,
+      description, NULL);
+
+  gst_caps_unref (caps);
+  g_free (description);
+
+  return gst_message_new_element (GST_OBJECT_CAST (element), s);
+}
+
+static gboolean
+missing_structure_get_string_detail (const GstStructure * s, gchar ** p_detail)
+{
+  const gchar *detail;
+  GType detail_type;
+
+  *p_detail = NULL;
+
+  detail_type = gst_structure_get_field_type (s, "detail");
+  if (!g_type_is_a (detail_type, G_TYPE_STRING)) {
+    GST_WARNING ("expected 'detail' field to be of G_TYPE_STRING");
+    return FALSE;
+  }
+
+  detail = gst_structure_get_string (s, "detail");
+  if (detail == NULL || *detail == '\0') {
+    GST_WARNING ("empty 'detail' field");
+    return FALSE;
+  }
+  *p_detail = g_strdup (detail);
+  return TRUE;
+}
+
+static gboolean
+missing_structure_get_caps_detail (const GstStructure * s, GstCaps ** p_caps)
+{
+  const GstCaps *caps;
+  const GValue *val;
+  GType detail_type;
+
+  *p_caps = NULL;
+
+  detail_type = gst_structure_get_field_type (s, "detail");
+  if (!g_type_is_a (detail_type, GST_TYPE_CAPS)) {
+    GST_WARNING ("expected 'detail' field to be of GST_TYPE_CAPS");
+    return FALSE;
+  }
+
+  val = gst_structure_get_value (s, "detail");
+  caps = gst_value_get_caps (val);
+  if (gst_caps_is_empty (caps) || gst_caps_is_any (caps)) {
+    GST_WARNING ("EMPTY or ANY caps not allowed");
+    return FALSE;
+  }
+
+  *p_caps = gst_caps_copy (caps);
+  return TRUE;
+}
+
+/**
+ * gst_missing_plugin_message_get_installer_detail:
+ * @msg: a missing-plugin #GstMessage of type #GST_MESSAGE_ELEMENT
+ *
+ * Returns an opaque string containing all the details about the missing
+ * element to be passed to an external installer called via
+ * gst_install_plugins_async() or gst_install_plugins_sync().
+ * 
+ * This function is mainly for applications that call external plugin
+ * installation mechanisms using one of the two above-mentioned functions.
+ *
+ * Returns: a newly-allocated detail string, or NULL on error. Free string
+ *          with g_free() when not needed any longer.
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+gchar *
+gst_missing_plugin_message_get_installer_detail (GstMessage * msg)
+{
+  GstMissingType missing_type;
+  const gchar *progname;
+  const gchar *type;
+  GString *str = NULL;
+  gchar *detail = NULL;
+  gchar *desc;
+
+  g_return_val_if_fail (gst_is_missing_plugin_message (msg), NULL);
+
+  GST_LOG ("Parsing missing-plugin message: %" GST_PTR_FORMAT, msg->structure);
+
+  missing_type = missing_structure_get_type (msg->structure);
+  if (missing_type == GST_MISSING_TYPE_UNKNOWN) {
+    GST_WARNING ("couldn't parse 'type' field");
+    goto error;
+  }
+
+  type = gst_structure_get_string (msg->structure, "type");
+  g_assert (type != NULL);      /* validity already checked above */
+
+  /* FIXME: use gst_installer_detail_new() here too */
+  str = g_string_new (GST_DETAIL_STRING_MARKER "|");
+  g_string_append_printf (str, "%u.%u|", GST_VERSION_MAJOR, GST_VERSION_MINOR);
+
+  progname = (const gchar *) g_get_prgname ();
+  if (progname) {
+    g_string_append_printf (str, "%s|", progname);
+  } else {
+    g_string_append_printf (str, "pid/%lu|", (gulong) getpid ());
+  }
+
+  desc = gst_missing_plugin_message_get_description (msg);
+  if (desc) {
+    g_strdelimit (desc, "|", '#');
+    g_string_append_printf (str, "%s|", desc);
+    g_free (desc);
+  } else {
+    g_string_append (str, "|");
+  }
+
+  switch (missing_type) {
+    case GST_MISSING_TYPE_URISOURCE:
+    case GST_MISSING_TYPE_URISINK:
+    case GST_MISSING_TYPE_ELEMENT:
+      if (!missing_structure_get_string_detail (msg->structure, &detail))
+        goto error;
+      break;
+    case GST_MISSING_TYPE_DECODER:
+    case GST_MISSING_TYPE_ENCODER:{
+      GstCaps *caps = NULL;
+
+      if (!missing_structure_get_caps_detail (msg->structure, &caps))
+        goto error;
+
+      detail = gst_caps_to_string (caps);
+      gst_caps_unref (caps);
+      break;
+    }
+    default:
+      g_return_val_if_reached (NULL);
+  }
+
+  g_string_append_printf (str, "%s-%s", type, detail);
+  g_free (detail);
+
+  return g_string_free (str, FALSE);
+
+/* ERRORS */
+error:
+  {
+    GST_WARNING ("Failed to parse missing-plugin msg: %" GST_PTR_FORMAT, msg);
+    if (str)
+      g_string_free (str, TRUE);
+    return NULL;
+  }
+}
+
+/**
+ * gst_missing_plugin_message_get_description:
+ * @msg: a missing-plugin #GstMessage of type #GST_MESSAGE_ELEMENT
+ *
+ * Returns a localised string describing the missing feature, for use in
+ * error dialogs and the like. Should never return NULL unless @msg is not
+ * a valid missing-plugin message.
+ *
+ * This function is mainly for applications that need a human-readable string
+ * describing a missing plugin, given a previously collected missing-plugin
+ * message
+ *
+ * Returns: a newly-allocated description string, or NULL on error. Free
+ *          string with g_free() when not needed any longer.
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+gchar *
+gst_missing_plugin_message_get_description (GstMessage * msg)
+{
+  GstMissingType missing_type;
+  const gchar *desc;
+  gchar *ret = NULL;
+
+  g_return_val_if_fail (gst_is_missing_plugin_message (msg), NULL);
+
+  GST_LOG ("Parsing missing-plugin message: %" GST_PTR_FORMAT, msg->structure);
+
+  desc = gst_structure_get_string (msg->structure, "name");
+  if (desc != NULL && *desc != '\0') {
+    ret = g_strdup (desc);
+    goto done;
+  }
+
+  /* fallback #1 */
+  missing_type = missing_structure_get_type (msg->structure);
+
+  switch (missing_type) {
+    case GST_MISSING_TYPE_URISOURCE:
+    case GST_MISSING_TYPE_URISINK:
+    case GST_MISSING_TYPE_ELEMENT:{
+      gchar *detail = NULL;
+
+      if (missing_structure_get_string_detail (msg->structure, &detail)) {
+        if (missing_type == GST_MISSING_TYPE_URISOURCE)
+          ret = gst_pb_utils_get_source_description (detail);
+        else if (missing_type == GST_MISSING_TYPE_URISINK)
+          ret = gst_pb_utils_get_sink_description (detail);
+        else
+          ret = gst_pb_utils_get_sink_description (detail);
+        g_free (detail);
+      }
+      break;
+    }
+    case GST_MISSING_TYPE_DECODER:
+    case GST_MISSING_TYPE_ENCODER:{
+      GstCaps *caps = NULL;
+
+      if (missing_structure_get_caps_detail (msg->structure, &caps)) {
+        if (missing_type == GST_MISSING_TYPE_DECODER)
+          ret = gst_pb_utils_get_decoder_description (caps);
+        else
+          ret = gst_pb_utils_get_encoder_description (caps);
+        gst_caps_unref (caps);
+      }
+      break;
+    }
+    default:
+      break;
+  }
+
+  if (ret)
+    goto done;
+
+  /* fallback #2 */
+  switch (missing_type) {
+    case GST_MISSING_TYPE_URISOURCE:
+      desc = _("Unknown source element");
+      break;
+    case GST_MISSING_TYPE_URISINK:
+      desc = _("Unknown sink element");
+      break;
+    case GST_MISSING_TYPE_ELEMENT:
+      desc = _("Unknown element");
+      break;
+    case GST_MISSING_TYPE_DECODER:
+      desc = _("Unknown decoder element");
+      break;
+    case GST_MISSING_TYPE_ENCODER:
+      desc = _("Unknown encoder element");
+      break;
+    default:
+      /* we should really never get here, but we better still return
+       * something if we do */
+      desc = _("Plugin or element of unknown type");
+      break;
+  }
+  ret = g_strdup (desc);
+
+done:
+
+  GST_LOG ("returning '%s'", ret);
+  return ret;
+}
+
+/**
+ * gst_is_missing_plugin_message:
+ * @msg: a #GstMessage
+ *
+ * Checks whether @msg is a missing plugins message.
+ *
+ * Returns: %TRUE if @msg is a missing-plugins message, otherwise %FALSE.
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+gboolean
+gst_is_missing_plugin_message (GstMessage * msg)
+{
+  g_return_val_if_fail (msg != NULL, FALSE);
+  g_return_val_if_fail (GST_IS_MESSAGE (msg), FALSE);
+
+  if (GST_MESSAGE_TYPE (msg) != GST_MESSAGE_ELEMENT || msg->structure == NULL)
+    return FALSE;
+
+  return gst_structure_has_name (msg->structure, "missing-plugin");
+}
+
+/* takes ownership of the description */
+static gchar *
+gst_installer_detail_new (gchar * description, const gchar * type,
+    const gchar * detail)
+{
+  const gchar *progname;
+  GString *s;
+
+  s = g_string_new (GST_DETAIL_STRING_MARKER "|");
+  g_string_append_printf (s, "%u.%u|", GST_VERSION_MAJOR, GST_VERSION_MINOR);
+
+  progname = (const gchar *) g_get_prgname ();
+  if (progname) {
+    g_string_append_printf (s, "%s|", progname);
+  } else {
+    g_string_append_printf (s, "pid/%lu|", (gulong) getpid ());
+  }
+
+  if (description) {
+    g_strdelimit (description, "|", '#');
+    g_string_append_printf (s, "%s|", description);
+    g_free (description);
+  } else {
+    g_string_append (s, "|");
+  }
+
+  g_string_append_printf (s, "%s-%s", type, detail);
+
+  return g_string_free (s, FALSE);
+}
+
+/**
+ * gst_missing_uri_source_installer_detail_new:
+ * @protocol: the URI protocol the missing source needs to implement,
+ *            e.g. "http" or "mms"
+ *
+ * Returns an opaque string containing all the details about the missing
+ * element to be passed to an external installer called via
+ * gst_install_plugins_async() or gst_install_plugins_sync().
+ * 
+ * This function is mainly for applications that call external plugin
+ * installation mechanisms using one of the two above-mentioned functions in
+ * the case where the application knows exactly what kind of plugin it is
+ * missing.
+ *
+ * Returns: a newly-allocated detail string, or NULL on error. Free string
+ *          with g_free() when not needed any longer.
+ *
+ * Since: 0.10.15
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+gchar *
+gst_missing_uri_source_installer_detail_new (const gchar * protocol)
+{
+  gchar *desc;
+
+  g_return_val_if_fail (protocol != NULL, NULL);
+
+  desc = gst_pb_utils_get_source_description (protocol);
+  return gst_installer_detail_new (desc, "urisource", protocol);
+}
+
+/**
+ * gst_missing_uri_sink_installer_detail_new:
+ * @protocol: the URI protocol the missing source needs to implement,
+ *            e.g. "http" or "mms"
+ *
+ * Returns an opaque string containing all the details about the missing
+ * element to be passed to an external installer called via
+ * gst_install_plugins_async() or gst_install_plugins_sync().
+ * 
+ * This function is mainly for applications that call external plugin
+ * installation mechanisms using one of the two above-mentioned functions in
+ * the case where the application knows exactly what kind of plugin it is
+ * missing.
+ *
+ * Returns: a newly-allocated detail string, or NULL on error. Free string
+ *          with g_free() when not needed any longer.
+ *
+ * Since: 0.10.15
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+gchar *
+gst_missing_uri_sink_installer_detail_new (const gchar * protocol)
+{
+  gchar *desc;
+
+  g_return_val_if_fail (protocol != NULL, NULL);
+
+  desc = gst_pb_utils_get_sink_description (protocol);
+  return gst_installer_detail_new (desc, "urisink", protocol);
+}
+
+/**
+ * gst_missing_element_installer_detail_new:
+ * @factory_name: the name of the missing element (element factory),
+ *            e.g. "videoscale" or "cdparanoiasrc"
+ *
+ * Returns an opaque string containing all the details about the missing
+ * element to be passed to an external installer called via
+ * gst_install_plugins_async() or gst_install_plugins_sync().
+ * 
+ * This function is mainly for applications that call external plugin
+ * installation mechanisms using one of the two above-mentioned functions in
+ * the case where the application knows exactly what kind of plugin it is
+ * missing.
+ *
+ * Returns: a newly-allocated detail string, or NULL on error. Free string
+ *          with g_free() when not needed any longer.
+ *
+ * Since: 0.10.15
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+gchar *
+gst_missing_element_installer_detail_new (const gchar * factory_name)
+{
+  gchar *desc;
+
+  g_return_val_if_fail (factory_name != NULL, NULL);
+
+  desc = gst_pb_utils_get_element_description (factory_name);
+  return gst_installer_detail_new (desc, "element", factory_name);
+}
+
+/**
+ * gst_missing_decoder_installer_detail_new:
+ * @decode_caps: the (fixed) caps for which a decoder element is needed
+ *
+ * Returns an opaque string containing all the details about the missing
+ * element to be passed to an external installer called via
+ * gst_install_plugins_async() or gst_install_plugins_sync().
+ * 
+ * This function is mainly for applications that call external plugin
+ * installation mechanisms using one of the two above-mentioned functions in
+ * the case where the application knows exactly what kind of plugin it is
+ * missing.
+ *
+ * Returns: a newly-allocated detail string, or NULL on error. Free string
+ *          with g_free() when not needed any longer.
+ *
+ * Since: 0.10.15
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+gchar *
+gst_missing_decoder_installer_detail_new (const GstCaps * decode_caps)
+{
+  GstCaps *caps;
+  gchar *detail_str, *caps_str, *desc;
+
+  g_return_val_if_fail (decode_caps != NULL, NULL);
+  g_return_val_if_fail (GST_IS_CAPS (decode_caps), NULL);
+  g_return_val_if_fail (!gst_caps_is_any (decode_caps), NULL);
+  g_return_val_if_fail (!gst_caps_is_empty (decode_caps), NULL);
+  g_return_val_if_fail (gst_caps_is_fixed (decode_caps), NULL);
+
+  desc = gst_pb_utils_get_decoder_description (decode_caps);
+  caps = copy_and_clean_caps (decode_caps);
+  caps_str = gst_caps_to_string (caps);
+  detail_str = gst_installer_detail_new (desc, "decoder", caps_str);
+  g_free (caps_str);
+  gst_caps_unref (caps);
+
+  return detail_str;
+}
+
+/**
+ * gst_missing_encoder_installer_detail_new:
+ * @encode_caps: the (fixed) caps for which an encoder element is needed
+ *
+ * Returns an opaque string containing all the details about the missing
+ * element to be passed to an external installer called via
+ * gst_install_plugins_async() or gst_install_plugins_sync().
+ * 
+ * This function is mainly for applications that call external plugin
+ * installation mechanisms using one of the two above-mentioned functions in
+ * the case where the application knows exactly what kind of plugin it is
+ * missing.
+ *
+ * Returns: a newly-allocated detail string, or NULL on error. Free string
+ *          with g_free() when not needed any longer.
+ *
+ * Since: 0.10.15
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+gchar *
+gst_missing_encoder_installer_detail_new (const GstCaps * encode_caps)
+{
+  GstCaps *caps;
+  gchar *detail_str, *caps_str, *desc;
+
+  g_return_val_if_fail (encode_caps != NULL, NULL);
+  g_return_val_if_fail (GST_IS_CAPS (encode_caps), NULL);
+  g_return_val_if_fail (!gst_caps_is_any (encode_caps), NULL);
+  g_return_val_if_fail (!gst_caps_is_empty (encode_caps), NULL);
+  g_return_val_if_fail (gst_caps_is_fixed (encode_caps), NULL);
+
+  desc = gst_pb_utils_get_encoder_description (encode_caps);
+  caps = copy_and_clean_caps (encode_caps);
+  caps_str = gst_caps_to_string (caps);
+  detail_str = gst_installer_detail_new (desc, "encoder", caps_str);
+  g_free (caps_str);
+  gst_caps_unref (caps);
+
+  return detail_str;
+}