path: root/gst/elements/gsttypefindelement.c

/* GStreamer
 * Copyright (C) 2003 Benjamin Otte <in7y118@public.uni-hamburg.de>
 *
 * gsttypefind.c: element that detects type of stream
 *
 * 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.
 */

/* FIXME: need a better solution for non-seekable streams */

/* way of operation:
 * 1) get a list of all typefind functions sorted best to worst
 * 2) if all elements have been called with all requested data goto 8
 * 3) call all functions once with all available data
 * 4) if a function returns a value >= ARG_MAXIMUM goto 8
 * 5) all functions with a result > ARG_MINIMUM or functions that did not get
 *    all requested data (where peek returned NULL) stay in list
 * 6) seek to requested offset of best function that still has open data 
 *    requests
 * 7) goto 2
 * 8) take best available result and use its caps
 */

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

#include "gsttypefindelement.h"
#include "gst/gst_private.h"

#include <gst/gsttypefind.h>

GST_DEBUG_CATEGORY_STATIC (gst_type_find_element_debug);
#define GST_CAT_DEFAULT gst_type_find_element_debug

GstElementDetails gst_type_find_element_details = GST_ELEMENT_DETAILS (
  "TypeFind",
  "Generic",
  "Finds the media type of a stream",
  "Benjamin Otte <in7y118@public.uni-hamburg.de>"
);

/* generic templates */
GstStaticPadTemplate type_find_element_sink_template = GST_STATIC_PAD_TEMPLATE (
  "sink",
  GST_PAD_SINK,
  GST_PAD_ALWAYS,
  GST_STATIC_CAPS_ANY
);

GstStaticPadTemplate type_find_element_src_template = GST_STATIC_PAD_TEMPLATE (
  "src",
  GST_PAD_SRC,
  GST_PAD_ALWAYS,
  GST_STATIC_CAPS_ANY
);

/* TypeFind signals and args */
enum {
  HAVE_TYPE,
  LAST_SIGNAL
};
enum {
  ARG_0,
  ARG_CAPS,
  ARG_MINIMUM,
  ARG_MAXIMUM
};
enum {
  MODE_NORMAL, /* act as identity */
  MODE_TYPEFIND, /* do typefinding */
};


static void	gst_type_find_element_base_init		(gpointer g_class);
static void	gst_type_find_element_class_init	(gpointer	g_class,
							 gpointer	class_data);
static void	gst_type_find_element_init		(GTypeInstance *instance,
							 gpointer	g_class);
static void	gst_type_find_element_dispose		(GObject *	object);
static void	gst_type_find_element_set_property	(GObject *	object, 
							 guint		prop_id,
							 const GValue *	value, 
						  	 GParamSpec *	pspec);
static void	gst_type_find_element_get_property	(GObject *	object, 
							 guint		prop_id,
						    	 GValue *	value, 
							 GParamSpec *	pspec);

static const GstEventMask *
                gst_type_find_element_src_event_mask    (GstPad *	pad);
static gboolean	gst_type_find_element_src_event		(GstPad *	pad,
		                                         GstEvent *	event);

static void	gst_type_find_element_chain		(GstPad *	sinkpad,
							 GstData *	data);
static GstElementStateReturn
		gst_type_find_element_change_state 	(GstElement *	element);

static GstElementClass *parent_class = NULL;
static guint gst_type_find_element_signals[LAST_SIGNAL] = { 0 };

GType
gst_type_find_element_get_type (void)
{
  static GType typefind_type = 0;

  if (!typefind_type) {
    static const GTypeInfo typefind_info = {
      sizeof (GstTypeFindElementClass),
      gst_type_find_element_base_init,
      NULL,
      gst_type_find_element_class_init,
      NULL,
      NULL,
      sizeof (GstTypeFindElement),
      0,
      gst_type_find_element_init,
      NULL
    };
    typefind_type = g_type_register_static (GST_TYPE_ELEMENT,
					    "GstTypeFindElement",
					    &typefind_info, 0);

    GST_DEBUG_CATEGORY_INIT (gst_type_find_element_debug, "typefind", 
			     GST_DEBUG_BG_YELLOW | GST_DEBUG_FG_GREEN, "typefind element");
  }
  return typefind_type;
}
static void
gst_type_find_element_have_type (GstTypeFindElement *typefind, guint probability, GstCaps *caps)
{
  gchar *caps_str;
  
  g_assert (typefind->caps == NULL);
  g_assert (caps != NULL);

  caps_str = gst_caps_to_string (caps);
  GST_INFO_OBJECT (typefind, "found caps %s", caps_str);
  g_free (caps_str);
  gst_caps_replace (&typefind->caps, caps);
  if (gst_pad_try_set_caps (typefind->src, caps) < GST_PAD_LINK_OK) {
    gst_element_error (GST_ELEMENT (typefind), "could not set caps on source pad");
  }
}
static void
gst_type_find_element_base_init (gpointer g_class)
{
  GstElementClass *gstelement_class = GST_ELEMENT_CLASS (g_class);
  
  gst_element_class_set_details (gstelement_class, &gst_type_find_element_details);
}
static void
gst_type_find_element_class_init (gpointer g_class, gpointer class_data)
{
  GObjectClass *gobject_class;
  GstElementClass *gstelement_class;
  GstTypeFindElementClass *typefind_class;

  gobject_class = G_OBJECT_CLASS (g_class);
  gstelement_class = GST_ELEMENT_CLASS (g_class);
  typefind_class = GST_TYPE_FIND_ELEMENT_CLASS (g_class);

  parent_class = g_type_class_peek_parent (g_class);

  gobject_class->set_property = GST_DEBUG_FUNCPTR (gst_type_find_element_set_property);
  gobject_class->get_property = GST_DEBUG_FUNCPTR (gst_type_find_element_get_property);
  gobject_class->dispose      =	GST_DEBUG_FUNCPTR (gst_type_find_element_dispose);

  typefind_class->have_type = gst_type_find_element_have_type;

  g_object_class_install_property (gobject_class, ARG_CAPS,
	  g_param_spec_boxed ("caps", _("caps"), _("detected capabilities in stream"),
	  gst_caps_get_type(), G_PARAM_READABLE));
  g_object_class_install_property (gobject_class, ARG_MINIMUM,
	  g_param_spec_uint ("minimum", _("minimum"), "minimum probability required to accept caps",
	  GST_TYPE_FIND_MINIMUM, GST_TYPE_FIND_MAXIMUM, GST_TYPE_FIND_MINIMUM, G_PARAM_READWRITE));
  g_object_class_install_property (gobject_class, ARG_MINIMUM,
	  g_param_spec_uint ("maximum", _("maximum"), "probability to stop typefinding",
	  GST_TYPE_FIND_MINIMUM, GST_TYPE_FIND_MAXIMUM, GST_TYPE_FIND_MAXIMUM, G_PARAM_READWRITE));

  gst_type_find_element_signals[HAVE_TYPE] = g_signal_new ("have_type", 
	  G_TYPE_FROM_CLASS (g_class), G_SIGNAL_RUN_LAST,
          G_STRUCT_OFFSET (GstTypeFindElementClass, have_type), NULL, NULL,
          gst_marshal_VOID__UINT_BOXED, G_TYPE_NONE, 2,
          G_TYPE_UINT, gst_caps_get_type());

  gstelement_class->change_state = GST_DEBUG_FUNCPTR (gst_type_find_element_change_state);
}
static void
gst_type_find_element_init (GTypeInstance *instance, gpointer g_class)
{
  GstTypeFindElement *typefind = GST_TYPE_FIND_ELEMENT (instance);
  
  /* sinkpad */
  typefind->sink = gst_pad_new_from_template (
      gst_static_pad_template_get (&type_find_element_sink_template), "sink");
  gst_pad_set_chain_function (typefind->sink,
			      gst_type_find_element_chain);
  gst_element_add_pad (GST_ELEMENT (typefind), typefind->sink);
  /* srcpad */
  typefind->src = gst_pad_new_from_template (
      gst_static_pad_template_get (&type_find_element_src_template), "src");
  gst_pad_set_event_function (typefind->src, gst_type_find_element_src_event);
  gst_pad_set_event_mask_function (typefind->src, gst_type_find_element_src_event_mask);
  gst_element_add_pad (GST_ELEMENT (typefind), typefind->src);

  typefind->caps = NULL;
  typefind->min_probability = 1;
  typefind->max_probability = GST_TYPE_FIND_MAXIMUM;

  typefind->store = gst_buffer_store_new ();

  GST_FLAG_SET (typefind, GST_ELEMENT_EVENT_AWARE);
}
static void
gst_type_find_element_dispose (GObject *object)
{
  GstTypeFindElement *typefind = GST_TYPE_FIND_ELEMENT (object);

  G_OBJECT_CLASS (parent_class)->dispose (object);

  if (typefind->store) {
    g_object_unref (typefind->store);
    typefind->store = NULL;
  }
}
static void
gst_type_find_element_set_property (GObject *object, guint prop_id, 
				    const GValue *value, GParamSpec *pspec)
{
  GstTypeFindElement *typefind;

  g_return_if_fail (GST_IS_TYPE_FIND_ELEMENT (object));

  typefind = GST_TYPE_FIND_ELEMENT (object);

  switch (prop_id) {
    case ARG_MINIMUM:
      typefind->min_probability = g_value_get_uint (value);
      g_object_notify (object, "minimum");
      break;
    case ARG_MAXIMUM:
      typefind->max_probability = g_value_get_uint (value);
      g_object_notify (object, "maximum");
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}
static void
gst_type_find_element_get_property (GObject *object, guint prop_id, 
				    GValue *value, GParamSpec *pspec)
{
  GstTypeFindElement *typefind;

  g_return_if_fail (GST_IS_TYPE_FIND_ELEMENT (object));

  typefind = GST_TYPE_FIND_ELEMENT (object);

  switch (prop_id) {
    case ARG_CAPS:
      g_value_set_boxed (value, typefind->caps);
      break;
    case ARG_MINIMUM:
      g_value_set_uint (value, typefind->min_probability);
      break;
    case ARG_MAXIMUM:
      g_value_set_uint (value, typefind->max_probability);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}
static const GstEventMask *
gst_type_find_element_src_event_mask (GstPad *pad)
{
  static const GstEventMask mask[] = {
    { GST_EVENT_SEEK, GST_SEEK_METHOD_SET | GST_SEEK_METHOD_CUR | GST_SEEK_METHOD_END | GST_SEEK_FLAG_FLUSH},
    /* add more if you want, event masks suck and need to die anyway */
    { 0, }
  };
  
  return mask;
}
static gboolean	
gst_type_find_element_src_event (GstPad *pad, GstEvent *event)
{
  GstTypeFindElement *typefind = GST_TYPE_FIND_ELEMENT (GST_PAD_PARENT (pad));

  if (typefind->mode == MODE_TYPEFIND) {
    /* need to do more? */
    gst_data_unref (GST_DATA (event));
    return FALSE;
  }
  return gst_pad_event_default (pad, event);
}
typedef struct {
  GstTypeFindFactory *	factory;
  gint			probability;
  GstCaps *		caps;
  gint64		requested_offset;
  guint			requested_size;

  GList *		buffers;
  GstTypeFindElement *	self;
} TypeFindEntry;
static void
free_entry_buffers (TypeFindEntry *entry)
{
  g_list_foreach (entry->buffers, (GFunc) gst_data_unref, NULL);
  g_list_free (entry->buffers);
  entry->buffers = NULL;
}
static void
free_entry (TypeFindEntry *entry)
{
  free_entry_buffers (entry);
  
  if (entry->caps)
    gst_caps_free (entry->caps);
  g_free (entry);
}
static void
start_typefinding (GstTypeFindElement *typefind)
{
  g_assert (typefind->caps == NULL);
  g_assert (typefind->possibilities == NULL);
  
  GST_DEBUG_OBJECT (typefind, "starting typefinding");
  typefind->mode = MODE_TYPEFIND; 
  typefind->stream_length_available = TRUE; 
  typefind->stream_length = 0; 
}
static void
stop_typefinding (GstTypeFindElement *typefind)
{
  /* stop all typefinding and set mode back to normal */
  gboolean push_cached_buffers = gst_element_get_state (GST_ELEMENT (typefind)) == GST_STATE_PLAYING;
  
  GST_DEBUG_OBJECT (typefind, "stopping typefinding%s", push_cached_buffers ? " and pushing cached buffers" : "");
  if (typefind->possibilities != NULL) {
    /* this should only happen on PAUSED => READY or EOS */
    GST_LOG_OBJECT (typefind, "freeing remaining %u typefind functions", g_list_length (typefind->possibilities));
    g_list_foreach (typefind->possibilities, (GFunc) free_entry, NULL);
    g_list_free (typefind->possibilities);
    typefind->possibilities = NULL;
  }

  typefind->mode = MODE_NORMAL;

  if (push_cached_buffers) {
    GstBuffer *buffer;
    guint size = gst_buffer_store_get_size (typefind->store, 0);

    GST_LOG_OBJECT (typefind, "seeking back to current position %u", size);
    if (!gst_pad_send_event (GST_PAD_PEER (typefind->sink), 
			     gst_event_new_seek (GST_SEEK_METHOD_SET | GST_FORMAT_BYTES, size))) {
      GST_WARNING_OBJECT (typefind, "could not seek to required position %u, hope for the best", size);
    }
    if (size && (buffer = gst_buffer_store_get_buffer (typefind->store, 0, size))) {
      gst_pad_push (typefind->src, GST_DATA (buffer));
    } else {
      size = 0;
    }
  }
  gst_buffer_store_clear (typefind->store);
}
static guint64
find_element_get_length (gpointer data)
{
  TypeFindEntry *entry = (TypeFindEntry *) data;
  GstTypeFindElement *typefind = entry->self;
  GstFormat format = GST_FORMAT_BYTES;
  
  if (!typefind->stream_length_available) {
    GST_LOG_OBJECT (entry->self, "'%s' called get_length () but we know it's not available", 
	    GST_PLUGIN_FEATURE_NAME (entry->factory));
    return 0;
  }
  if (entry->self->stream_length == 0) {
    typefind->stream_length_available = gst_pad_query (GST_PAD_PEER (entry->self->sink), GST_QUERY_TOTAL, 
	    &format, &entry->self->stream_length);
    if (format != GST_FORMAT_BYTES)
      typefind->stream_length_available = FALSE;
    if (!typefind->stream_length_available) {
      GST_DEBUG_OBJECT (entry->self, "'%s' called get_length () but it's not available", 
	      GST_PLUGIN_FEATURE_NAME (entry->factory));
      return 0;
    } else {
      GST_DEBUG_OBJECT (entry->self, "'%s' called get_length () and it's %"G_GUINT64_FORMAT" bytes", 
	      GST_PLUGIN_FEATURE_NAME (entry->factory), entry->self->stream_length);
    }
  }
  
  return entry->self->stream_length;
}
static void
gst_type_find_element_handle_event (GstPad *pad, GstEvent *event)
{
  TypeFindEntry *entry;
  GstTypeFindElement *typefind = GST_TYPE_FIND_ELEMENT (GST_PAD_PARENT (pad));

  if (typefind->mode == MODE_TYPEFIND) {
    /* need to do more? */
    switch (GST_EVENT_TYPE (event)) {
    case GST_EVENT_EOS:
      /* this should only happen when we got all available data */
      entry = (TypeFindEntry *) typefind->possibilities ? typefind->possibilities->data : NULL;
      if (entry && entry->probability >= typefind->min_probability) {
	GST_INFO_OBJECT (typefind, "'%s' is the best typefind left after we got all data, using it now (probability %u)", 
		GST_PLUGIN_FEATURE_NAME (entry->factory), entry->probability);
	g_signal_emit (typefind, gst_type_find_element_signals[HAVE_TYPE], 0, entry->probability, entry->caps);
      }
      stop_typefinding (typefind);
      gst_pad_event_default (pad, event);
      break;
    default:
      gst_data_unref (GST_DATA (event));
      break;
    }
  } else {
    gst_pad_event_default (pad, event);
  }
}
static guint8 *
find_peek (gpointer data, gint64 offset, guint size)
{
  GstBuffer *buf;
  TypeFindEntry *entry = (TypeFindEntry *) data;
  
  GST_LOG_OBJECT (entry->self, "'%s' called peek (%"G_GINT64_FORMAT", %u)", 
	  GST_PLUGIN_FEATURE_NAME (entry->factory), offset, size);
  if (offset >= 0) {
    buf = gst_buffer_store_get_buffer (entry->self->store, offset, size);
  } else {
    /* FIXME: can we do this easily without querying length? */
    guint64 length = find_element_get_length (data);

    if (length == 0) {
      buf = NULL;
    } else {
      buf = gst_buffer_store_get_buffer (entry->self->store, length + offset, size);
    }
  }

  if (buf) {
    entry->buffers = g_list_prepend (entry->buffers, buf);
    return GST_BUFFER_DATA (buf);
  } else {
    if (entry->requested_size == 0) {
      GST_LOG_OBJECT (entry->self, "setting requested peek (%"G_GINT64_FORMAT", %u) on '%s'", 
	      offset, size, GST_PLUGIN_FEATURE_NAME (entry->factory));
      entry->requested_offset = offset;
      entry->requested_size = size;
    }
    return NULL;
  }
}
static void
find_suggest (gpointer data, guint probability, const GstCaps *caps)
{
  gchar *str;
  TypeFindEntry *entry = (TypeFindEntry *) data;
  
  str = gst_caps_to_string (caps);
  GST_LOG_OBJECT (entry->self, "'%s' called suggest (%u, %s)", 
	  GST_PLUGIN_FEATURE_NAME (entry->factory), probability, str);
  g_free (str);
  if (((gint) probability) > entry->probability) {
    entry->probability = probability;
    gst_caps_replace (&entry->caps, gst_caps_copy (caps));
  }
}
static gint
compare_type_find_entry (gconstpointer a, gconstpointer b)
{
  TypeFindEntry *one = (TypeFindEntry *) a;
  TypeFindEntry *two = (TypeFindEntry *) b;

  if (one->probability == two->probability) {
    /* FIXME: can be improved by analyzing requests */
    return 0;
  } else {
    return two->probability - one->probability;
  }
}
static gint
compare_type_find_factory (gconstpointer fac1, gconstpointer fac2)
{
  return GST_PLUGIN_FEATURE (fac1)->rank - GST_PLUGIN_FEATURE (fac2)->rank;
}
static void
gst_type_find_element_chain (GstPad *pad, GstData *data)
{
  GstTypeFindElement *typefind;
  GList *entries;
  TypeFindEntry *entry;
  GList *walk;
  GstTypeFind find = {find_peek, find_suggest, NULL, find_element_get_length };

  typefind = GST_TYPE_FIND_ELEMENT (GST_PAD_PARENT (pad));
  if (GST_IS_EVENT (data)) {
    gst_type_find_element_handle_event (pad, GST_EVENT (data));
    return;
  }
  switch (typefind->mode) {
    case MODE_NORMAL:
      gst_pad_push (typefind->src, data);
      return;
    case MODE_TYPEFIND: {
      gst_buffer_store_add_buffer (typefind->store, GST_BUFFER (data));
      gst_data_unref (data);
      if (typefind->possibilities == NULL) {
	/* not yet started, get all typefinding functions into our "queue" */
	GList *all_factories = gst_type_find_factory_get_list ();
	GST_INFO_OBJECT (typefind, "starting with %u typefinding functions", 
	                 g_list_length ((GList *) all_factories));
	
	all_factories = g_list_sort (all_factories, compare_type_find_factory);
	walk = all_factories;
	while (all_factories) {
	  entry = g_new0 (TypeFindEntry, 1);
	  
	  entry->factory = GST_TYPE_FIND_FACTORY (all_factories->data);
	  entry->self = typefind;
	  entry->probability = 0;
	  typefind->possibilities = g_list_prepend (typefind->possibilities, entry);
	  all_factories = g_list_next (all_factories);
	}
	g_list_free (all_factories);
      }
      /* call every typefind function once */
      walk = entries = typefind->possibilities;
      GST_INFO_OBJECT (typefind, "iterating %u typefinding functions", g_list_length (entries));
      typefind->possibilities = NULL;
      while (walk) {
	find.data = entry = (TypeFindEntry *) walk->data;
	walk = g_list_next (walk);
	entry->probability = 0;
	entry->requested_offset = 0;
	entry->requested_size = 0;
	gst_type_find_factory_call_function (entry->factory, &find);
	free_entry_buffers (entry);
	if (entry->probability == 0 && entry->requested_size == 0) {
	  GST_DEBUG_OBJECT (typefind, "'%s' was removed - no chance of being the right plugin", 
		  GST_PLUGIN_FEATURE_NAME (entry->factory));
	  free_entry (entry);
	} else if (entry->probability >= typefind->max_probability) {
	  /* wooha, got caps */
	  GstCaps *found_caps = entry->caps;
	  guint probability = entry->probability;
	  
	  found_caps = gst_caps_copy (found_caps);
	  GST_INFO_OBJECT (typefind, "'%s' returned %u/%u probability, using it NOW", 
		  GST_PLUGIN_FEATURE_NAME (entry->factory), probability, typefind->max_probability);
	  while (walk) {
	    free_entry ((TypeFindEntry *) walk->data);
	    walk = g_list_next (walk);
	  }
	  walk = typefind->possibilities;
	  while (walk) {
	    free_entry (walk->data);
	    walk = g_list_next (walk);
	  }
	  typefind->possibilities = NULL;
	  g_list_free (typefind->possibilities); 
	  g_signal_emit (typefind, gst_type_find_element_signals[HAVE_TYPE], 0, probability, found_caps);
	  gst_caps_free (found_caps);
	} else {
	  typefind->possibilities = g_list_prepend (typefind->possibilities, entry);
	}
      }
      g_list_free (entries);
      /* we may now already have caps or we might be left without functions to try */
      if (typefind->caps) {
	stop_typefinding (typefind);
      } else if (typefind->possibilities == NULL) {
	gst_element_error (GST_ELEMENT (typefind), "media type could not be detected");
      } else {
	/* set up typefind element for next iteration */
	typefind->possibilities = g_list_sort (typefind->possibilities, compare_type_find_entry);
	
	walk = typefind->possibilities;
	while (walk) {
	  entry = (TypeFindEntry *) walk->data;
	  walk = g_list_next (walk);
	  if (entry->requested_size > 0) {
	    /* FIXME: need heuristic to find out if we should seek */
	    gint64 seek_offset;
	    GstEvent *event;

	    seek_offset = entry->requested_offset > 0 ? entry->requested_offset : 
			  find_element_get_length (entry) + entry->requested_offset;
	    seek_offset += gst_buffer_store_get_size (typefind->store, seek_offset);
	    event = gst_event_new_seek (GST_FORMAT_BYTES | GST_SEEK_METHOD_SET, seek_offset);
	    if (gst_pad_send_event (GST_PAD_PEER (typefind->sink), event)) {
	      /* done seeking */
	      GST_DEBUG_OBJECT (typefind, "'%s' was reset - seeked to %"G_GINT64_FORMAT, 
		      GST_PLUGIN_FEATURE_NAME (entry->factory), seek_offset);
	      break;
	    } else if (entry->requested_offset < 0) {
	      /* impossible to seek */
	      GST_DEBUG_OBJECT (typefind, "'%s' was reset - couldn't seek to %"G_GINT64_FORMAT, 
		      GST_PLUGIN_FEATURE_NAME (entry->factory), seek_offset);
	      entry->requested_size = 0;
	      entry->requested_offset = 0;
	    }
	  }
	}
	/* throw out all entries that can't get more data */
	walk = g_list_next (typefind->possibilities);
	while (walk) {
	  GList *cur = walk;
	  entry = (TypeFindEntry *) walk->data;
	  walk = g_list_next (walk);
	  if (entry->requested_size == 0) {
	    GST_DEBUG_OBJECT (typefind, "'%s' was removed - higher possibilities available", 
		    GST_PLUGIN_FEATURE_NAME (entry->factory));
	    free_entry (entry);
	    typefind->possibilities = g_list_delete_link (typefind->possibilities, cur);
	  }
	}
	if (g_list_next (typefind->possibilities) == NULL) {
	  entry = (TypeFindEntry *) typefind->possibilities->data;
	  if (entry->probability > typefind->min_probability) {
	    GST_INFO_OBJECT (typefind, "'%s' is the only typefind left, using it now (probability %u)", 
		    GST_PLUGIN_FEATURE_NAME (entry->factory), entry->probability);
	    g_signal_emit (typefind, gst_type_find_element_signals[HAVE_TYPE], 0, entry->probability, entry->caps);
	    free_entry (entry);
	    g_list_free (typefind->possibilities);
	    typefind->possibilities = NULL;
	    stop_typefinding (typefind);
	  }
	}
      }
      break;
    }
    default:
      g_assert_not_reached ();
      return;
  }
}
static GstElementStateReturn
gst_type_find_element_change_state (GstElement *element)
{
  GstTypeFindElement *typefind;

  typefind = GST_TYPE_FIND_ELEMENT (element);

  switch (GST_STATE_TRANSITION (element)) {
    case GST_STATE_READY_TO_PAUSED:
      start_typefinding (typefind);
      break;
    case GST_STATE_PAUSED_TO_READY:
      stop_typefinding (typefind);
      gst_caps_replace (&typefind->caps, NULL);
      break;
    default:
      break;
  }
  
  return GST_ELEMENT_CLASS (parent_class)->change_state (element);
}