gst/gstcapsfeatures.c - mtk-gstreamer-debian - Git at Google

 /* GStreamer
  * Copyright (C) 2013 Collabora Ltd.
  *   Author: Sebastian Dröge <sebastian.droege@collabora.co.uk>
  *
  * 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., 51 Franklin St, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */

 /**
  * SECTION:gstcapsfeatures
  * @short_description: A set of features in caps
  * @see_also: #GstCaps
  *
  * #GstCapsFeatures can optionally be set on a #GstCaps to add requirements
  * for additional features for a specific #GstStructure. Caps structures with
  * the same name but with a non-equal set of caps features are not compatible.
  * If a pad supports multiple sets of features it has to add multiple equal
  * structures with different feature sets to the caps.
  *
  * Empty #GstCapsFeatures are equivalent with the #GstCapsFeatures that only
  * contain #GST_CAPS_FEATURE_MEMORY_SYSTEM_MEMORY. ANY #GstCapsFeatures as
  * created by gst_caps_features_new_any() are equal to any other #GstCapsFeatures
  * and can be used to specify that any #GstCapsFeatures would be supported, e.g.
  * for elements that don't touch buffer memory. #GstCaps with ANY #GstCapsFeatures
  * are considered non-fixed and during negotiation some #GstCapsFeatures have
  * to be selected.
  *
  * Examples for caps features would be the requirement of a specific #GstMemory
  * types or the requirement of having a specific #GstMeta on the buffer. Features
  * are given as a string of the format "memory:GstMemoryTypeName" or
  * "meta:GstMetaAPIName".
  *
  * Since: 1.2
  */

 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif

 #include <string.h>
 #include "gst_private.h"
 #include "gstcapsfeatures.h"
 #include <gst/gst.h>

 GST_DEBUG_CATEGORY_STATIC (gst_caps_features_debug);
 #define GST_CAT_DEFAULT gst_caps_features_debug

 struct _GstCapsFeatures
 {
   GType type;
   gint *parent_refcount;
   GArray *array;
   gboolean is_any;
 };

 GType _gst_caps_features_type = 0;
 static gint static_caps_features_parent_refcount = G_MAXINT;
 GstCapsFeatures *_gst_caps_features_any = NULL;
 GstCapsFeatures *_gst_caps_features_memory_system_memory = NULL;
 static GQuark _gst_caps_feature_memory_system_memory = 0;

 G_DEFINE_BOXED_TYPE (GstCapsFeatures, gst_caps_features,
     gst_caps_features_copy, gst_caps_features_free);

 #define IS_MUTABLE(features) \
     (!features->parent_refcount || \
      g_atomic_int_get (features->parent_refcount) == 1)

 static void
 gst_caps_features_transform_to_string (const GValue * src_value,
     GValue * dest_value);

 void
 _priv_gst_caps_features_initialize (void)
 {
   GST_DEBUG_CATEGORY_INIT (gst_caps_features_debug, "caps-features", 0,
       "GstCapsFeatures debug");

   _gst_caps_features_type = gst_caps_features_get_type ();
   _gst_caps_feature_memory_system_memory =
       g_quark_from_static_string (GST_CAPS_FEATURE_MEMORY_SYSTEM_MEMORY);

   g_value_register_transform_func (_gst_caps_features_type, G_TYPE_STRING,
       gst_caps_features_transform_to_string);

   _gst_caps_features_any = gst_caps_features_new_any ();
   gst_caps_features_set_parent_refcount (_gst_caps_features_any,
       &static_caps_features_parent_refcount);
   _gst_caps_features_memory_system_memory =
       gst_caps_features_new_id (_gst_caps_feature_memory_system_memory, 0);
   gst_caps_features_set_parent_refcount
       (_gst_caps_features_memory_system_memory,
       &static_caps_features_parent_refcount);
 }

 gboolean
 gst_is_caps_features (gconstpointer obj)
 {
   const GstCapsFeatures *features = obj;

   return (obj != NULL && features->type == _gst_caps_features_type);
 }

 static gboolean
 gst_caps_feature_name_is_valid (const gchar * feature)
 {
 #ifndef G_DISABLE_CHECKS
   while (TRUE) {
     if (g_ascii_isalpha (*feature))
       feature++;
     else if (*feature == ':')
       break;
     else
       return FALSE;
   }

   if (*feature != ':')
     return FALSE;

   feature++;
   if (*feature == '\0' || !g_ascii_isalpha (*feature))
     return FALSE;

   while (TRUE) {
     if (g_ascii_isalnum (*feature))
       feature++;
     else if (*feature == '\0')
       break;
     else
       return FALSE;
   }
 #endif

   return TRUE;
 }

 /**
  * gst_caps_features_new_empty:
  *
  * Creates a new, empty #GstCapsFeatures.
  *
  * Free-function: gst_caps_features_free
  *
  * Returns: (transfer full): a new, empty #GstCapsFeatures
  *
  * Since: 1.2
  */
 GstCapsFeatures *
 gst_caps_features_new_empty (void)
 {
   GstCapsFeatures *features;

   features = g_slice_new (GstCapsFeatures);
   features->type = _gst_caps_features_type;
   features->parent_refcount = NULL;
   features->array = g_array_new (FALSE, FALSE, sizeof (GQuark));
   features->is_any = FALSE;

   GST_TRACE ("created caps features %p", features);

   return features;
 }

 /**
  * gst_caps_features_new_any:
  *
  * Creates a new, ANY #GstCapsFeatures. This will be equal
  * to any other #GstCapsFeatures but caps with these are
  * unfixed.
  *
  * Free-function: gst_caps_features_free
  *
  * Returns: (transfer full): a new, ANY #GstCapsFeatures
  *
  * Since: 1.2
  */
 GstCapsFeatures *
 gst_caps_features_new_any (void)
 {
   GstCapsFeatures *features;

   features = gst_caps_features_new_empty ();
   features->is_any = TRUE;

   return features;
 }

 /**
  * gst_caps_features_new:
  * @feature1: name of first feature to set
  * @...: additional features
  *
  * Creates a new #GstCapsFeatures with the given features.
  * The last argument must be %NULL.
  *
  * Free-function: gst_caps_features_free
  *
  * Returns: (transfer full): a new, empty #GstCapsFeatures
  *
  * Since: 1.2
  */
 GstCapsFeatures *
 gst_caps_features_new (const gchar * feature1, ...)
 {
   GstCapsFeatures *features;
   va_list varargs;

   g_return_val_if_fail (feature1 != NULL, NULL);

   va_start (varargs, feature1);
   features = gst_caps_features_new_valist (feature1, varargs);
   va_end (varargs);

   return features;
 }

 /**
  * gst_caps_features_new_valist:
  * @feature1: name of first feature to set
  * @varargs: variable argument list
  *
  * Creates a new #GstCapsFeatures with the given features.
  *
  * Free-function: gst_caps_features_free
  *
  * Returns: (transfer full): a new, empty #GstCapsFeatures
  *
  * Since: 1.2
  */
 GstCapsFeatures *
 gst_caps_features_new_valist (const gchar * feature1, va_list varargs)
 {
   GstCapsFeatures *features;

   g_return_val_if_fail (feature1 != NULL, NULL);

   features = gst_caps_features_new_empty ();

   while (feature1) {
     gst_caps_features_add (features, feature1);
     feature1 = va_arg (varargs, const gchar *);
   }

   return features;
 }

 /**
  * gst_caps_features_new_id:
  * @feature1: name of first feature to set
  * @...: additional features
  *
  * Creates a new #GstCapsFeatures with the given features.
  * The last argument must be 0.
  *
  * Free-function: gst_caps_features_free
  *
  * Returns: (transfer full): a new, empty #GstCapsFeatures
  *
  * Since: 1.2
  */
 GstCapsFeatures *
 gst_caps_features_new_id (GQuark feature1, ...)
 {
   GstCapsFeatures *features;
   va_list varargs;

   g_return_val_if_fail (feature1 != 0, NULL);

   va_start (varargs, feature1);
   features = gst_caps_features_new_id_valist (feature1, varargs);
   va_end (varargs);

   return features;
 }

 /**
  * gst_caps_features_new_id_valist:
  * @feature1: name of first feature to set
  * @varargs: variable argument list
  *
  * Creates a new #GstCapsFeatures with the given features.
  *
  * Free-function: gst_caps_features_free
  *
  * Returns: (transfer full): a new, empty #GstCapsFeatures
  *
  * Since: 1.2
  */
 GstCapsFeatures *
 gst_caps_features_new_id_valist (GQuark feature1, va_list varargs)
 {
   GstCapsFeatures *features;

   g_return_val_if_fail (feature1 != 0, NULL);

   features = gst_caps_features_new_empty ();

   while (feature1) {
     gst_caps_features_add_id (features, feature1);
     feature1 = va_arg (varargs, GQuark);
   }

   return features;
 }

 /**
  * gst_caps_features_set_parent_refcount:
  * @features: a #GstCapsFeatures
  * @refcount: (in): a pointer to the parent's refcount
  *
  * Sets the parent_refcount field of #GstCapsFeatures. This field is used to
  * determine whether a caps features is mutable or not. This function should only be
  * called by code implementing parent objects of #GstCapsFeatures, as described in
  * the MT Refcounting section of the design documents.
  *
  * Returns: %TRUE if the parent refcount could be set.
  *
  * Since: 1.2
  */
 gboolean
 gst_caps_features_set_parent_refcount (GstCapsFeatures * features,
     gint * refcount)
 {
   g_return_val_if_fail (features != NULL, FALSE);

   /* if we have a parent_refcount already, we can only clear
    * if with a NULL refcount */
   if (features->parent_refcount) {
     if (refcount != NULL) {
       g_return_val_if_fail (refcount == NULL, FALSE);
       return FALSE;
     }
   } else {
     if (refcount == NULL) {
       g_return_val_if_fail (refcount != NULL, FALSE);
       return FALSE;
     }
   }

   features->parent_refcount = refcount;

   return TRUE;
 }

 /**
  * gst_caps_features_copy:
  * @features: a #GstCapsFeatures to duplicate
  *
  * Duplicates a #GstCapsFeatures and all its values.
  *
  * Free-function: gst_caps_features_free
  *
  * Returns: (transfer full): a new #GstCapsFeatures.
  *
  * Since: 1.2
  */
 GstCapsFeatures *
 gst_caps_features_copy (const GstCapsFeatures * features)
 {
   GstCapsFeatures *copy;
   guint i, n;

   g_return_val_if_fail (features != NULL, NULL);

   copy = gst_caps_features_new_empty ();
   n = gst_caps_features_get_size (features);
   for (i = 0; i < n; i++)
     gst_caps_features_add_id (copy, gst_caps_features_get_nth_id (features, i));
   copy->is_any = features->is_any;

   return copy;
 }

 /**
  * gst_caps_features_free:
  * @features: (in) (transfer full): the #GstCapsFeatures to free
  *
  * Frees a #GstCapsFeatures and all its values. The caps features must not
  * have a parent when this function is called.
  *
  * Since: 1.2
  */
 void
 gst_caps_features_free (GstCapsFeatures * features)
 {
   g_return_if_fail (features != NULL);
   g_return_if_fail (features->parent_refcount == NULL);

   g_array_free (features->array, TRUE);
 #ifdef USE_POISONING
   memset (features, 0xff, sizeof (GstCapsFeatures));
 #endif
   GST_TRACE ("free caps features %p", features);

   g_slice_free (GstCapsFeatures, features);
 }

 /**
  * gst_caps_features_to_string:
  * @features: a #GstCapsFeatures
  *
  * Converts @features to a human-readable string representation.
  *
  * For debugging purposes its easier to do something like this:
  * |[
  * GST_LOG ("features is %" GST_PTR_FORMAT, features);
  * ]|
  * This prints the features in human readable form.
  *
  * Free-function: g_free
  *
  * Returns: (transfer full): a pointer to string allocated by g_malloc().
  *     g_free() after usage.
  *
  * Since: 1.2
  */
 gchar *
 gst_caps_features_to_string (const GstCapsFeatures * features)
 {
   GString *s;

   g_return_val_if_fail (features != NULL, NULL);

   s = g_string_sized_new (FEATURES_ESTIMATED_STRING_LEN (features));

   priv_gst_caps_features_append_to_gstring (features, s);

   return g_string_free (s, FALSE);
 }

 void
 priv_gst_caps_features_append_to_gstring (const GstCapsFeatures * features,
     GString * s)
 {
   guint i, n;

   g_return_if_fail (features != NULL);

   if (features->array->len == 0 && features->is_any) {
     g_string_append (s, "ANY");
     return;
   }

   n = features->array->len;
   for (i = 0; i < n; i++) {
     GQuark *quark = &g_array_index (features->array, GQuark, i);

     g_string_append (s, g_quark_to_string (*quark));
     if (i + 1 < n)
       g_string_append (s, ", ");
   }
 }

 /**
  * gst_caps_features_from_string:
  * @features: a string representation of a #GstCapsFeatures.
  *
  * Creates a #GstCapsFeatures from a string representation.
  *
  * Free-function: gst_caps_features_free
  *
  * Returns: (transfer full) (nullable): a new #GstCapsFeatures or
  *     %NULL when the string could not be parsed. Free with
  *     gst_caps_features_free() after use.
  *
  * Since: 1.2
  */
 GstCapsFeatures *
 gst_caps_features_from_string (const gchar * features)
 {
   GstCapsFeatures *ret;
   gboolean escape = FALSE;
   const gchar *features_orig = features;
   const gchar *feature;

   ret = gst_caps_features_new_empty ();

   if (!features || *features == '\0')
     return ret;

   if (strcmp (features, "ANY") == 0) {
     ret->is_any = TRUE;
     return ret;
   }

   /* Skip trailing spaces */
   while (*features == ' ')
     features++;

   feature = features;
   while (TRUE) {
     gchar c = *features;

     if (c == '\\') {
       escape = TRUE;
       features++;
       continue;
     } else if ((!escape && c == ',') || c == '\0') {
       guint len = features - feature + 1;
       gchar *tmp;
       gchar *p;

       if (len == 1) {
         g_warning ("Failed deserialize caps features '%s'", features_orig);
         gst_caps_features_free (ret);
         return NULL;
       }

       tmp = g_malloc (len);
       memcpy (tmp, feature, len - 1);
       tmp[len - 1] = '\0';

       p = tmp + len - 1;
       while (*p == ' ') {
         *p = '\0';
         p--;
       }

       if (strstr (tmp, " ") != NULL || *tmp == '\0') {
         g_free (tmp);
         g_warning ("Failed deserialize caps features '%s'", features_orig);
         gst_caps_features_free (ret);
         return NULL;
       }

       gst_caps_features_add (ret, tmp);
       g_free (tmp);

       if (c == '\0')
         break;

       /* Skip to the next value */
       features++;
       while (*features == ' ')
         features++;
       feature = features;
     } else {
       escape = FALSE;
       features++;
     }
   }

   return ret;
 }

 /**
  * gst_caps_features_get_size:
  * @features: a #GstCapsFeatures.
  *
  * Returns the number of features in @features.
  *
  * Returns: The number of features in @features.
  *
  * Since: 1.2
  */
 guint
 gst_caps_features_get_size (const GstCapsFeatures * features)
 {
   g_return_val_if_fail (features != NULL, 0);

   return features->array->len;
 }

 /**
  * gst_caps_features_get_nth:
  * @features: a #GstCapsFeatures.
  * @i: index of the feature
  *
  * Returns the @i-th feature of @features.
  *
  * Returns: The @i-th feature of @features.
  *
  * Since: 1.2
  */
 const gchar *
 gst_caps_features_get_nth (const GstCapsFeatures * features, guint i)
 {
   const gchar *feature;
   GQuark quark;

   g_return_val_if_fail (features != NULL, NULL);

   quark = gst_caps_features_get_nth_id (features, i);
   if (!quark)
     return NULL;

   feature = g_quark_to_string (quark);
   return feature;
 }

 /**
  * gst_caps_features_get_nth_id:
  * @features: a #GstCapsFeatures.
  * @i: index of the feature
  *
  * Returns the @i-th feature of @features.
  *
  * Returns: The @i-th feature of @features.
  *
  * Since: 1.2
  */
 GQuark
 gst_caps_features_get_nth_id (const GstCapsFeatures * features, guint i)
 {
   GQuark *quark;

   g_return_val_if_fail (features != NULL, 0);
   g_return_val_if_fail (i < features->array->len, 0);

   quark = &g_array_index (features->array, GQuark, i);

   return *quark;
 }

 /**
  * gst_caps_features_contains:
  * @features: a #GstCapsFeatures.
  * @feature: a feature
  *
  * Check if @features contains @feature.
  *
  * Returns: %TRUE if @features contains @feature.
  *
  * Since: 1.2
  */
 gboolean
 gst_caps_features_contains (const GstCapsFeatures * features,
     const gchar * feature)
 {
   g_return_val_if_fail (features != NULL, FALSE);
   g_return_val_if_fail (feature != NULL, FALSE);

   return gst_caps_features_contains_id (features,
       g_quark_from_string (feature));
 }

 /**
  * gst_caps_features_contains_id:
  * @features: a #GstCapsFeatures.
  * @feature: a feature
  *
  * Check if @features contains @feature.
  *
  * Returns: %TRUE if @features contains @feature.
  *
  * Since: 1.2
  */
 gboolean
 gst_caps_features_contains_id (const GstCapsFeatures * features, GQuark feature)
 {
   guint i, n;

   g_return_val_if_fail (features != NULL, FALSE);
   g_return_val_if_fail (feature != 0, FALSE);

   if (features->is_any)
     return TRUE;

   n = features->array->len;
   if (n == 0)
     return feature == _gst_caps_feature_memory_system_memory;

   for (i = 0; i < n; i++) {
     if (gst_caps_features_get_nth_id (features, i) == feature)
       return TRUE;
   }

   return FALSE;
 }

 /**
  * gst_caps_features_is_equal:
  * @features1: a #GstCapsFeatures.
  * @features2: a #GstCapsFeatures.
  *
  * Check if @features1 and @features2 are equal.
  *
  * Returns: %TRUE if @features1 and @features2 are equal.
  *
  * Since: 1.2
  */
 gboolean
 gst_caps_features_is_equal (const GstCapsFeatures * features1,
     const GstCapsFeatures * features2)
 {
   guint i, n;

   g_return_val_if_fail (features1 != NULL, FALSE);
   g_return_val_if_fail (features2 != NULL, FALSE);

   if (features1->is_any || features2->is_any)
     return TRUE;

   /* Check for the sysmem==empty case */
   if (features1->array->len == 0 && features2->array->len == 0)
     return TRUE;
   if (features1->array->len == 0 && features2->array->len == 1
       && gst_caps_features_contains_id (features2,
           _gst_caps_feature_memory_system_memory))
     return TRUE;
   if (features2->array->len == 0 && features1->array->len == 1
       && gst_caps_features_contains_id (features1,
           _gst_caps_feature_memory_system_memory))
     return TRUE;

   if (features1->array->len != features2->array->len)
     return FALSE;

   n = features1->array->len;
   for (i = 0; i < n; i++)
     if (!gst_caps_features_contains_id (features2,
             gst_caps_features_get_nth_id (features1, i)))
       return FALSE;

   return TRUE;
 }

 /**
  * gst_caps_features_is_any:
  * @features: a #GstCapsFeatures.
  *
  * Check if @features is %GST_CAPS_FEATURES_ANY.
  *
  * Returns: %TRUE if @features is %GST_CAPS_FEATURES_ANY.
  *
  * Since: 1.2
  */
 gboolean
 gst_caps_features_is_any (const GstCapsFeatures * features)
 {
   g_return_val_if_fail (features != NULL, FALSE);

   return features->is_any;
 }

 /**
  * gst_caps_features_add:
  * @features: a #GstCapsFeatures.
  * @feature: a feature.
  *
  * Adds @feature to @features.
  *
  * Since: 1.2
  */
 void
 gst_caps_features_add (GstCapsFeatures * features, const gchar * feature)
 {
   g_return_if_fail (features != NULL);
   g_return_if_fail (IS_MUTABLE (features));
   g_return_if_fail (feature != NULL);
   g_return_if_fail (!features->is_any);

   gst_caps_features_add_id (features, g_quark_from_string (feature));
 }

 /**
  * gst_caps_features_add_id:
  * @features: a #GstCapsFeatures.
  * @feature: a feature.
  *
  * Adds @feature to @features.
  *
  * Since: 1.2
  */
 void
 gst_caps_features_add_id (GstCapsFeatures * features, GQuark feature)
 {
   g_return_if_fail (features != NULL);
   g_return_if_fail (IS_MUTABLE (features));
   g_return_if_fail (feature != 0);
   g_return_if_fail (!features->is_any);

   if (!gst_caps_feature_name_is_valid (g_quark_to_string (feature))) {
     g_warning ("Invalid caps feature name: %s", g_quark_to_string (feature));
     return;
   }

   /* If features is empty it will contain sysmem, however
    * we want to add it explicitely if it is tried to be
    * added as first features
    */
   if (features->array->len > 0
       && gst_caps_features_contains_id (features, feature))
     return;

   g_array_append_val (features->array, feature);
 }

 /**
  * gst_caps_features_remove:
  * @features: a #GstCapsFeatures.
  * @feature: a feature.
  *
  * Removes @feature from @features.
  *
  * Since: 1.2
  */
 void
 gst_caps_features_remove (GstCapsFeatures * features, const gchar * feature)
 {
   g_return_if_fail (features != NULL);
   g_return_if_fail (IS_MUTABLE (features));
   g_return_if_fail (feature != NULL);

   gst_caps_features_remove_id (features, g_quark_from_string (feature));
 }

 /**
  * gst_caps_features_remove_id:
  * @features: a #GstCapsFeatures.
  * @feature: a feature.
  *
  * Removes @feature from @features.
  *
  * Since: 1.2
  */
 void
 gst_caps_features_remove_id (GstCapsFeatures * features, GQuark feature)
 {
   guint i, n;

   g_return_if_fail (features != NULL);
   g_return_if_fail (IS_MUTABLE (features));
   g_return_if_fail (feature != 0);

   n = features->array->len;
   for (i = 0; i < n; i++) {
     GQuark quark = gst_caps_features_get_nth_id (features, i);

     if (quark == feature) {
       g_array_remove_index_fast (features->array, i);
       return;
     }
   }
 }

 static void
 gst_caps_features_transform_to_string (const GValue * src_value,
     GValue * dest_value)
 {
   g_return_if_fail (src_value != NULL);
   g_return_if_fail (dest_value != NULL);

   dest_value->data[0].v_pointer =
       gst_caps_features_to_string (src_value->data[0].v_pointer);
 }
	/* GStreamer
	* Copyright (C) 2013 Collabora Ltd.
	* Author: Sebastian Dröge <sebastian.droege@collabora.co.uk>
	*
	* 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., 51 Franklin St, Fifth Floor,
	* Boston, MA 02110-1301, USA.
	*/

	/**
	* SECTION:gstcapsfeatures
	* @short_description: A set of features in caps
	* @see_also: #GstCaps
	*
	* #GstCapsFeatures can optionally be set on a #GstCaps to add requirements
	* for additional features for a specific #GstStructure. Caps structures with
	* the same name but with a non-equal set of caps features are not compatible.
	* If a pad supports multiple sets of features it has to add multiple equal
	* structures with different feature sets to the caps.
	*
	* Empty #GstCapsFeatures are equivalent with the #GstCapsFeatures that only
	* contain #GST_CAPS_FEATURE_MEMORY_SYSTEM_MEMORY. ANY #GstCapsFeatures as
	* created by gst_caps_features_new_any() are equal to any other #GstCapsFeatures
	* and can be used to specify that any #GstCapsFeatures would be supported, e.g.
	* for elements that don't touch buffer memory. #GstCaps with ANY #GstCapsFeatures
	* are considered non-fixed and during negotiation some #GstCapsFeatures have
	* to be selected.
	*
	* Examples for caps features would be the requirement of a specific #GstMemory
	* types or the requirement of having a specific #GstMeta on the buffer. Features
	* are given as a string of the format "memory:GstMemoryTypeName" or
	* "meta:GstMetaAPIName".
	*
	* Since: 1.2
	*/

	#ifdef HAVE_CONFIG_H
	#include "config.h"
	#endif

	#include <string.h>
	#include "gst_private.h"
	#include "gstcapsfeatures.h"
	#include <gst/gst.h>

	GST_DEBUG_CATEGORY_STATIC (gst_caps_features_debug);
	#define GST_CAT_DEFAULT gst_caps_features_debug

	struct _GstCapsFeatures
	{
	GType type;
	gint *parent_refcount;
	GArray *array;
	gboolean is_any;
	};

	GType _gst_caps_features_type = 0;
	static gint static_caps_features_parent_refcount = G_MAXINT;
	GstCapsFeatures *_gst_caps_features_any = NULL;
	GstCapsFeatures *_gst_caps_features_memory_system_memory = NULL;
	static GQuark _gst_caps_feature_memory_system_memory = 0;

	G_DEFINE_BOXED_TYPE (GstCapsFeatures, gst_caps_features,
	gst_caps_features_copy, gst_caps_features_free);

	#define IS_MUTABLE(features) \
	(!features->parent_refcount \|\| \
	g_atomic_int_get (features->parent_refcount) == 1)

	static void
	gst_caps_features_transform_to_string (const GValue * src_value,
	GValue * dest_value);

	void
	_priv_gst_caps_features_initialize (void)
	{
	GST_DEBUG_CATEGORY_INIT (gst_caps_features_debug, "caps-features", 0,
	"GstCapsFeatures debug");

	_gst_caps_features_type = gst_caps_features_get_type ();
	_gst_caps_feature_memory_system_memory =
	g_quark_from_static_string (GST_CAPS_FEATURE_MEMORY_SYSTEM_MEMORY);

	g_value_register_transform_func (_gst_caps_features_type, G_TYPE_STRING,
	gst_caps_features_transform_to_string);

	_gst_caps_features_any = gst_caps_features_new_any ();
	gst_caps_features_set_parent_refcount (_gst_caps_features_any,
	&static_caps_features_parent_refcount);
	_gst_caps_features_memory_system_memory =
	gst_caps_features_new_id (_gst_caps_feature_memory_system_memory, 0);
	gst_caps_features_set_parent_refcount
	(_gst_caps_features_memory_system_memory,
	&static_caps_features_parent_refcount);
	}

	gboolean
	gst_is_caps_features (gconstpointer obj)
	{
	const GstCapsFeatures *features = obj;

	return (obj != NULL && features->type == _gst_caps_features_type);
	}

	static gboolean
	gst_caps_feature_name_is_valid (const gchar * feature)
	{
	#ifndef G_DISABLE_CHECKS
	while (TRUE) {
	if (g_ascii_isalpha (*feature))
	feature++;
	else if (*feature == ':')
	break;
	else
	return FALSE;
	}

	if (*feature != ':')
	return FALSE;

	feature++;
	if (feature == '\0' \|\| !g_ascii_isalpha (feature))
	return FALSE;

	while (TRUE) {
	if (g_ascii_isalnum (*feature))
	feature++;
	else if (*feature == '\0')
	break;
	else
	return FALSE;
	}
	#endif

	return TRUE;
	}

	/**
	* gst_caps_features_new_empty:
	*
	* Creates a new, empty #GstCapsFeatures.
	*
	* Free-function: gst_caps_features_free
	*
	* Returns: (transfer full): a new, empty #GstCapsFeatures
	*
	* Since: 1.2
	*/
	GstCapsFeatures *
	gst_caps_features_new_empty (void)
	{
	GstCapsFeatures *features;

	features = g_slice_new (GstCapsFeatures);
	features->type = _gst_caps_features_type;
	features->parent_refcount = NULL;
	features->array = g_array_new (FALSE, FALSE, sizeof (GQuark));
	features->is_any = FALSE;

	GST_TRACE ("created caps features %p", features);

	return features;
	}

	/**
	* gst_caps_features_new_any:
	*
	* Creates a new, ANY #GstCapsFeatures. This will be equal
	* to any other #GstCapsFeatures but caps with these are
	* unfixed.
	*
	* Free-function: gst_caps_features_free
	*
	* Returns: (transfer full): a new, ANY #GstCapsFeatures
	*
	* Since: 1.2
	*/
	GstCapsFeatures *
	gst_caps_features_new_any (void)
	{
	GstCapsFeatures *features;

	features = gst_caps_features_new_empty ();
	features->is_any = TRUE;

	return features;
	}

	/**
	* gst_caps_features_new:
	* @feature1: name of first feature to set
	* @...: additional features
	*
	* Creates a new #GstCapsFeatures with the given features.
	* The last argument must be %NULL.
	*
	* Free-function: gst_caps_features_free
	*
	* Returns: (transfer full): a new, empty #GstCapsFeatures
	*
	* Since: 1.2
	*/
	GstCapsFeatures *
	gst_caps_features_new (const gchar * feature1, ...)
	{
	GstCapsFeatures *features;
	va_list varargs;

	g_return_val_if_fail (feature1 != NULL, NULL);

	va_start (varargs, feature1);
	features = gst_caps_features_new_valist (feature1, varargs);
	va_end (varargs);

	return features;
	}

	/**
	* gst_caps_features_new_valist:
	* @feature1: name of first feature to set
	* @varargs: variable argument list
	*
	* Creates a new #GstCapsFeatures with the given features.
	*
	* Free-function: gst_caps_features_free
	*
	* Returns: (transfer full): a new, empty #GstCapsFeatures
	*
	* Since: 1.2
	*/
	GstCapsFeatures *
	gst_caps_features_new_valist (const gchar * feature1, va_list varargs)
	{
	GstCapsFeatures *features;

	g_return_val_if_fail (feature1 != NULL, NULL);

	features = gst_caps_features_new_empty ();

	while (feature1) {
	gst_caps_features_add (features, feature1);
	feature1 = va_arg (varargs, const gchar *);
	}

	return features;
	}

	/**
	* gst_caps_features_new_id:
	* @feature1: name of first feature to set
	* @...: additional features
	*
	* Creates a new #GstCapsFeatures with the given features.
	* The last argument must be 0.
	*
	* Free-function: gst_caps_features_free
	*
	* Returns: (transfer full): a new, empty #GstCapsFeatures
	*
	* Since: 1.2
	*/
	GstCapsFeatures *
	gst_caps_features_new_id (GQuark feature1, ...)
	{
	GstCapsFeatures *features;
	va_list varargs;

	g_return_val_if_fail (feature1 != 0, NULL);

	va_start (varargs, feature1);
	features = gst_caps_features_new_id_valist (feature1, varargs);
	va_end (varargs);

	return features;
	}

	/**
	* gst_caps_features_new_id_valist:
	* @feature1: name of first feature to set
	* @varargs: variable argument list
	*
	* Creates a new #GstCapsFeatures with the given features.
	*
	* Free-function: gst_caps_features_free
	*
	* Returns: (transfer full): a new, empty #GstCapsFeatures
	*
	* Since: 1.2
	*/
	GstCapsFeatures *
	gst_caps_features_new_id_valist (GQuark feature1, va_list varargs)
	{
	GstCapsFeatures *features;

	g_return_val_if_fail (feature1 != 0, NULL);

	features = gst_caps_features_new_empty ();

	while (feature1) {
	gst_caps_features_add_id (features, feature1);
	feature1 = va_arg (varargs, GQuark);
	}

	return features;
	}

	/**
	* gst_caps_features_set_parent_refcount:
	* @features: a #GstCapsFeatures
	* @refcount: (in): a pointer to the parent's refcount
	*
	* Sets the parent_refcount field of #GstCapsFeatures. This field is used to
	* determine whether a caps features is mutable or not. This function should only be
	* called by code implementing parent objects of #GstCapsFeatures, as described in
	* the MT Refcounting section of the design documents.
	*
	* Returns: %TRUE if the parent refcount could be set.
	*
	* Since: 1.2
	*/
	gboolean
	gst_caps_features_set_parent_refcount (GstCapsFeatures * features,
	gint * refcount)
	{
	g_return_val_if_fail (features != NULL, FALSE);

	/* if we have a parent_refcount already, we can only clear
	* if with a NULL refcount */
	if (features->parent_refcount) {
	if (refcount != NULL) {
	g_return_val_if_fail (refcount == NULL, FALSE);
	return FALSE;
	}
	} else {
	if (refcount == NULL) {
	g_return_val_if_fail (refcount != NULL, FALSE);
	return FALSE;
	}
	}

	features->parent_refcount = refcount;

	return TRUE;
	}

	/**
	* gst_caps_features_copy:
	* @features: a #GstCapsFeatures to duplicate
	*
	* Duplicates a #GstCapsFeatures and all its values.
	*
	* Free-function: gst_caps_features_free
	*
	* Returns: (transfer full): a new #GstCapsFeatures.
	*
	* Since: 1.2
	*/
	GstCapsFeatures *
	gst_caps_features_copy (const GstCapsFeatures * features)
	{
	GstCapsFeatures *copy;
	guint i, n;

	g_return_val_if_fail (features != NULL, NULL);

	copy = gst_caps_features_new_empty ();
	n = gst_caps_features_get_size (features);
	for (i = 0; i < n; i++)
	gst_caps_features_add_id (copy, gst_caps_features_get_nth_id (features, i));
	copy->is_any = features->is_any;

	return copy;
	}

	/**
	* gst_caps_features_free:
	* @features: (in) (transfer full): the #GstCapsFeatures to free
	*
	* Frees a #GstCapsFeatures and all its values. The caps features must not
	* have a parent when this function is called.
	*
	* Since: 1.2
	*/
	void
	gst_caps_features_free (GstCapsFeatures * features)
	{
	g_return_if_fail (features != NULL);
	g_return_if_fail (features->parent_refcount == NULL);

	g_array_free (features->array, TRUE);
	#ifdef USE_POISONING
	memset (features, 0xff, sizeof (GstCapsFeatures));
	#endif
	GST_TRACE ("free caps features %p", features);

	g_slice_free (GstCapsFeatures, features);
	}

	/**
	* gst_caps_features_to_string:
	* @features: a #GstCapsFeatures
	*
	* Converts @features to a human-readable string representation.
	*
	* For debugging purposes its easier to do something like this:
	* \|[
	* GST_LOG ("features is %" GST_PTR_FORMAT, features);
	* ]\|
	* This prints the features in human readable form.
	*
	* Free-function: g_free
	*
	* Returns: (transfer full): a pointer to string allocated by g_malloc().
	* g_free() after usage.
	*
	* Since: 1.2
	*/
	gchar *
	gst_caps_features_to_string (const GstCapsFeatures * features)
	{
	GString *s;

	g_return_val_if_fail (features != NULL, NULL);

	s = g_string_sized_new (FEATURES_ESTIMATED_STRING_LEN (features));

	priv_gst_caps_features_append_to_gstring (features, s);

	return g_string_free (s, FALSE);
	}

	void
	priv_gst_caps_features_append_to_gstring (const GstCapsFeatures * features,
	GString * s)
	{
	guint i, n;

	g_return_if_fail (features != NULL);

	if (features->array->len == 0 && features->is_any) {
	g_string_append (s, "ANY");
	return;
	}

	n = features->array->len;
	for (i = 0; i < n; i++) {
	GQuark *quark = &g_array_index (features->array, GQuark, i);

	g_string_append (s, g_quark_to_string (*quark));
	if (i + 1 < n)
	g_string_append (s, ", ");
	}
	}

	/**
	* gst_caps_features_from_string:
	* @features: a string representation of a #GstCapsFeatures.
	*
	* Creates a #GstCapsFeatures from a string representation.
	*
	* Free-function: gst_caps_features_free
	*
	* Returns: (transfer full) (nullable): a new #GstCapsFeatures or
	* %NULL when the string could not be parsed. Free with
	* gst_caps_features_free() after use.
	*
	* Since: 1.2
	*/
	GstCapsFeatures *
	gst_caps_features_from_string (const gchar * features)
	{
	GstCapsFeatures *ret;
	gboolean escape = FALSE;
	const gchar *features_orig = features;
	const gchar *feature;

	ret = gst_caps_features_new_empty ();

	if (!features \|\| *features == '\0')
	return ret;

	if (strcmp (features, "ANY") == 0) {
	ret->is_any = TRUE;
	return ret;
	}

	/* Skip trailing spaces */
	while (*features == ' ')
	features++;

	feature = features;
	while (TRUE) {
	gchar c = *features;

	if (c == '\\') {
	escape = TRUE;
	features++;
	continue;
	} else if ((!escape && c == ',') \|\| c == '\0') {
	guint len = features - feature + 1;
	gchar *tmp;
	gchar *p;

	if (len == 1) {
	g_warning ("Failed deserialize caps features '%s'", features_orig);
	gst_caps_features_free (ret);
	return NULL;
	}

	tmp = g_malloc (len);
	memcpy (tmp, feature, len - 1);
	tmp[len - 1] = '\0';

	p = tmp + len - 1;
	while (*p == ' ') {
	*p = '\0';
	p--;
	}

	if (strstr (tmp, " ") != NULL \|\| *tmp == '\0') {
	g_free (tmp);
	g_warning ("Failed deserialize caps features '%s'", features_orig);
	gst_caps_features_free (ret);
	return NULL;
	}

	gst_caps_features_add (ret, tmp);
	g_free (tmp);

	if (c == '\0')
	break;

	/* Skip to the next value */
	features++;
	while (*features == ' ')
	features++;
	feature = features;
	} else {
	escape = FALSE;
	features++;
	}
	}

	return ret;
	}

	/**
	* gst_caps_features_get_size:
	* @features: a #GstCapsFeatures.
	*
	* Returns the number of features in @features.
	*
	* Returns: The number of features in @features.
	*
	* Since: 1.2
	*/
	guint
	gst_caps_features_get_size (const GstCapsFeatures * features)
	{
	g_return_val_if_fail (features != NULL, 0);

	return features->array->len;
	}

	/**
	* gst_caps_features_get_nth:
	* @features: a #GstCapsFeatures.
	* @i: index of the feature
	*
	* Returns the @i-th feature of @features.
	*
	* Returns: The @i-th feature of @features.
	*
	* Since: 1.2
	*/
	const gchar *
	gst_caps_features_get_nth (const GstCapsFeatures * features, guint i)
	{
	const gchar *feature;
	GQuark quark;

	g_return_val_if_fail (features != NULL, NULL);

	quark = gst_caps_features_get_nth_id (features, i);
	if (!quark)
	return NULL;

	feature = g_quark_to_string (quark);
	return feature;
	}

	/**
	* gst_caps_features_get_nth_id:
	* @features: a #GstCapsFeatures.
	* @i: index of the feature
	*
	* Returns the @i-th feature of @features.
	*
	* Returns: The @i-th feature of @features.
	*
	* Since: 1.2
	*/
	GQuark
	gst_caps_features_get_nth_id (const GstCapsFeatures * features, guint i)
	{
	GQuark *quark;

	g_return_val_if_fail (features != NULL, 0);
	g_return_val_if_fail (i < features->array->len, 0);

	quark = &g_array_index (features->array, GQuark, i);

	return *quark;
	}

	/**
	* gst_caps_features_contains:
	* @features: a #GstCapsFeatures.
	* @feature: a feature
	*
	* Check if @features contains @feature.
	*
	* Returns: %TRUE if @features contains @feature.
	*
	* Since: 1.2
	*/
	gboolean
	gst_caps_features_contains (const GstCapsFeatures * features,
	const gchar * feature)
	{
	g_return_val_if_fail (features != NULL, FALSE);
	g_return_val_if_fail (feature != NULL, FALSE);

	return gst_caps_features_contains_id (features,
	g_quark_from_string (feature));
	}

	/**
	* gst_caps_features_contains_id:
	* @features: a #GstCapsFeatures.
	* @feature: a feature
	*
	* Check if @features contains @feature.
	*
	* Returns: %TRUE if @features contains @feature.
	*
	* Since: 1.2
	*/
	gboolean
	gst_caps_features_contains_id (const GstCapsFeatures * features, GQuark feature)
	{
	guint i, n;

	g_return_val_if_fail (features != NULL, FALSE);
	g_return_val_if_fail (feature != 0, FALSE);

	if (features->is_any)
	return TRUE;

	n = features->array->len;
	if (n == 0)
	return feature == _gst_caps_feature_memory_system_memory;

	for (i = 0; i < n; i++) {
	if (gst_caps_features_get_nth_id (features, i) == feature)
	return TRUE;
	}

	return FALSE;
	}

	/**
	* gst_caps_features_is_equal:
	* @features1: a #GstCapsFeatures.
	* @features2: a #GstCapsFeatures.
	*
	* Check if @features1 and @features2 are equal.
	*
	* Returns: %TRUE if @features1 and @features2 are equal.
	*
	* Since: 1.2
	*/
	gboolean
	gst_caps_features_is_equal (const GstCapsFeatures * features1,
	const GstCapsFeatures * features2)
	{
	guint i, n;

	g_return_val_if_fail (features1 != NULL, FALSE);
	g_return_val_if_fail (features2 != NULL, FALSE);

	if (features1->is_any \|\| features2->is_any)
	return TRUE;

	/* Check for the sysmem==empty case */
	if (features1->array->len == 0 && features2->array->len == 0)
	return TRUE;
	if (features1->array->len == 0 && features2->array->len == 1
	&& gst_caps_features_contains_id (features2,
	_gst_caps_feature_memory_system_memory))
	return TRUE;
	if (features2->array->len == 0 && features1->array->len == 1
	&& gst_caps_features_contains_id (features1,
	_gst_caps_feature_memory_system_memory))
	return TRUE;

	if (features1->array->len != features2->array->len)
	return FALSE;

	n = features1->array->len;
	for (i = 0; i < n; i++)
	if (!gst_caps_features_contains_id (features2,
	gst_caps_features_get_nth_id (features1, i)))
	return FALSE;

	return TRUE;
	}

	/**
	* gst_caps_features_is_any:
	* @features: a #GstCapsFeatures.
	*
	* Check if @features is %GST_CAPS_FEATURES_ANY.
	*
	* Returns: %TRUE if @features is %GST_CAPS_FEATURES_ANY.
	*
	* Since: 1.2
	*/
	gboolean
	gst_caps_features_is_any (const GstCapsFeatures * features)
	{
	g_return_val_if_fail (features != NULL, FALSE);

	return features->is_any;
	}

	/**
	* gst_caps_features_add:
	* @features: a #GstCapsFeatures.
	* @feature: a feature.
	*
	* Adds @feature to @features.
	*
	* Since: 1.2
	*/
	void
	gst_caps_features_add (GstCapsFeatures * features, const gchar * feature)
	{
	g_return_if_fail (features != NULL);
	g_return_if_fail (IS_MUTABLE (features));
	g_return_if_fail (feature != NULL);
	g_return_if_fail (!features->is_any);

	gst_caps_features_add_id (features, g_quark_from_string (feature));
	}

	/**
	* gst_caps_features_add_id:
	* @features: a #GstCapsFeatures.
	* @feature: a feature.
	*
	* Adds @feature to @features.
	*
	* Since: 1.2
	*/
	void
	gst_caps_features_add_id (GstCapsFeatures * features, GQuark feature)
	{
	g_return_if_fail (features != NULL);
	g_return_if_fail (IS_MUTABLE (features));
	g_return_if_fail (feature != 0);
	g_return_if_fail (!features->is_any);

	if (!gst_caps_feature_name_is_valid (g_quark_to_string (feature))) {
	g_warning ("Invalid caps feature name: %s", g_quark_to_string (feature));
	return;
	}

	/* If features is empty it will contain sysmem, however
	* we want to add it explicitely if it is tried to be
	* added as first features
	*/
	if (features->array->len > 0
	&& gst_caps_features_contains_id (features, feature))
	return;

	g_array_append_val (features->array, feature);
	}

	/**
	* gst_caps_features_remove:
	* @features: a #GstCapsFeatures.
	* @feature: a feature.
	*
	* Removes @feature from @features.
	*
	* Since: 1.2
	*/
	void
	gst_caps_features_remove (GstCapsFeatures * features, const gchar * feature)
	{
	g_return_if_fail (features != NULL);
	g_return_if_fail (IS_MUTABLE (features));
	g_return_if_fail (feature != NULL);

	gst_caps_features_remove_id (features, g_quark_from_string (feature));
	}

	/**
	* gst_caps_features_remove_id:
	* @features: a #GstCapsFeatures.
	* @feature: a feature.
	*
	* Removes @feature from @features.
	*
	* Since: 1.2
	*/
	void
	gst_caps_features_remove_id (GstCapsFeatures * features, GQuark feature)
	{
	guint i, n;

	g_return_if_fail (features != NULL);
	g_return_if_fail (IS_MUTABLE (features));
	g_return_if_fail (feature != 0);

	n = features->array->len;
	for (i = 0; i < n; i++) {
	GQuark quark = gst_caps_features_get_nth_id (features, i);

	if (quark == feature) {
	g_array_remove_index_fast (features->array, i);
	return;
	}
	}
	}

	static void
	gst_caps_features_transform_to_string (const GValue * src_value,
	GValue * dest_value)
	{
	g_return_if_fail (src_value != NULL);
	g_return_if_fail (dest_value != NULL);

	dest_value->data[0].v_pointer =
	gst_caps_features_to_string (src_value->data[0].v_pointer);
	}