gstreamer_core/libs/gst/base/gstbasesrc.c
changeset 0 0e761a78d257
child 8 4a7fac7dd34a
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gstreamer_core/libs/gst/base/gstbasesrc.c	Thu Dec 17 08:53:32 2009 +0200
@@ -0,0 +1,2738 @@
+/* GStreamer
+ * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
+ *               2000,2005 Wim Taymans <wim@fluendo.com>
+ *
+ * gstbasesrc.c:
+ *
+ * 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:gstbasesrc
+ * @short_description: Base class for getrange based source elements
+ * @see_also: #GstPushSrc, #GstBaseTransform, #GstBaseSink
+ *
+ * This is a generice base class for source elements. The following
+ * types of sources are supported:
+ * <itemizedlist>
+ *   <listitem><para>random access sources like files</para></listitem>
+ *   <listitem><para>seekable sources</para></listitem>
+ *   <listitem><para>live sources</para></listitem>
+ * </itemizedlist>
+ *
+ * <refsect2>
+ * <para>
+ * The source can be configured to operate in any #GstFormat with the
+ * gst_base_src_set_format() method. The currently set format determines 
+ * the format of the internal #GstSegment and any #GST_EVENT_NEWSEGMENT 
+ * events. The default format for #GstBaseSrc is #GST_FORMAT_BYTES.
+ * </para>
+ * <para>
+ * #GstBaseSrc always supports push mode scheduling. If the following
+ * conditions are met, it also supports pull mode scheduling:
+ * <itemizedlist>
+ *   <listitem><para>The format is set to #GST_FORMAT_BYTES (default).</para>
+ *   </listitem>
+ *   <listitem><para>#GstBaseSrc::is_seekable returns %TRUE.</para>
+ *   </listitem>
+ * </itemizedlist>
+ * </para>
+ * <para>
+ * Since 0.10.9, any #GstBaseSrc can enable pull based scheduling at any 
+ * time by overriding #GstBaseSrc::check_get_range so that it returns %TRUE. 
+ * </para>
+ * <para>
+ * If all the conditions are met for operating in pull mode, #GstBaseSrc is
+ * automatically seekable in push mode as well. The following conditions must 
+ * be met to make the element seekable in push mode when the format is not
+ * #GST_FORMAT_BYTES:
+ * <itemizedlist>
+ *   <listitem><para>
+ *     #GstBaseSrc::is_seekable returns %TRUE.
+ *   </para></listitem>
+ *   <listitem><para>
+ *     #GstBaseSrc::query can convert all supported seek formats to the
+ *     internal format as set with gst_base_src_set_format().
+ *   </para></listitem>
+ *   <listitem><para>
+ *     #GstBaseSrc::do_seek is implemented, performs the seek and returns %TRUE.
+ *   </para></listitem>
+ * </itemizedlist>
+ * </para>
+ * <para>
+ * When the element does not meet the requirements to operate in pull mode,
+ * the offset and length in the #GstBaseSrc::create method should be ignored.
+ * It is recommended to subclass #GstPushSrc instead, in this situation. If the
+ * element can operate in pull mode but only with specific offsets and
+ * lengths, it is allowed to generate an error when the wrong values are passed
+ * to the #GstBaseSrc::create function.
+ * </para>
+ * <para>
+ * #GstBaseSrc has support for live sources. Live sources are sources that when
+ * paused discard data, such as audio or video capture devices. A typical live
+ * source also produces data at a fixed rate and thus provides a clock to publish
+ * this rate.
+ * Use gst_base_src_set_live() to activate the live source mode.
+ * </para>
+ * <para>
+ * A live source does not produce data in the PAUSED state. This means that the 
+ * #GstBaseSrc::create method will not be called in PAUSED but only in PLAYING.
+ * To signal the pipeline that the element will not produce data, the return
+ * value from the READY to PAUSED state will be #GST_STATE_CHANGE_NO_PREROLL.
+ * </para>
+ * <para>
+ * A typical live source will timestamp the buffers it creates with the 
+ * current running time of the pipeline. This is one reason why a live source
+ * can only produce data in the PLAYING state, when the clock is actually 
+ * distributed and running. 
+ * </para>
+ * <para>
+ * Live sources that synchronize and block on the clock (an audio source, for
+ * example) can since 0.10.12 use gst_base_src_wait_playing() when the ::create
+ * function was interrupted by a state change to PAUSED.
+ * </para>
+ * <para>
+ * The #GstBaseSrc::get_times method can be used to implement pseudo-live 
+ * sources.
+ * It only makes sense to implement the ::get_times function if the source is 
+ * a live source. The ::get_times function should return timestamps starting
+ * from 0, as if it were a non-live source. The base class will make sure that
+ * the timestamps are transformed into the current running_time.
+ * The base source will then wait for the calculated running_time before pushing
+ * out the buffer.
+ * </para>
+ * <para>
+ * For live sources, the base class will by default report a latency of 0.
+ * For pseudo live sources, the base class will by default measure the difference
+ * between the first buffer timestamp and the start time of get_times and will
+ * report this value as the latency. 
+ * Subclasses should override the query function when this behaviour is not
+ * acceptable.
+ * </para>
+ * <para>
+ * There is only support in #GstBaseSrc for exactly one source pad, which 
+ * should be named "src". A source implementation (subclass of #GstBaseSrc) 
+ * should install a pad template in its class_init function, like so:
+ * </para>
+ * <para>
+ * <programlisting>
+ * static void
+ * my_element_class_init (GstMyElementClass *klass)
+ * {
+ *   GstElementClass *gstelement_class = GST_ELEMENT_CLASS (klass);
+ *   // srctemplate should be a #GstStaticPadTemplate with direction
+ *   // #GST_PAD_SRC and name "src"
+ *   gst_element_class_add_pad_template (gstelement_class,
+ *       gst_static_pad_template_get (&amp;srctemplate));
+ *   // see #GstElementDetails
+ *   gst_element_class_set_details (gstelement_class, &amp;details);
+ * }
+ * </programlisting>
+ * </para>
+ * <title>Controlled shutdown of live sources in applications</title>
+ * <para>
+ * Applications that record from a live source may want to stop recording
+ * in a controlled way, so that the recording is stopped, but the data
+ * already in the pipeline is processed to the end (remember that many live
+ * sources would go on recording forever otherwise). For that to happen the
+ * application needs to make the source stop recording and send an EOS
+ * event down the pipeline. The application would then wait for an
+ * EOS message posted on the pipeline's bus to know when all data has
+ * been processed and the pipeline can safely be stopped.
+ * </para>
+ * <para>
+ * Since GStreamer 0.10.16 an application may send an EOS event to a source
+ * element to make it send an EOS event downstream. This can typically be done
+ * with the gst_element_send_event() function on the element or its parent bin.
+ * </para>
+ * <para>
+ * After the EOS has been sent to the element, the application should wait for
+ * an EOS message to be posted on the pipeline's bus. Once this EOS message is
+ * received, it may safely shut down the entire pipeline.
+ * </para>
+ * <para>
+ * The old behaviour for controlled shutdown introduced since GStreamer 0.10.3
+ * is still available but deprecated as it is dangerous and less flexible.
+ * </para>
+ * <para>
+ * Last reviewed on 2007-12-19 (0.10.16)
+ * </para>
+ * </refsect2>
+ */
+
+#ifdef HAVE_CONFIG_H
+#  include "config.h"
+#endif
+
+#ifdef __SYMBIAN32__
+#include <gst_global.h>
+#endif
+#include <stdlib.h>
+#include <string.h>
+
+#include "gstbasesrc.h"
+#include "gsttypefindhelper.h"
+#include <gst/gstmarshal.h>
+#include <gst/gst-i18n-lib.h>
+
+#ifdef __SYMBIAN32__
+#include <glib_global.h>
+#include <gobject_global.h>
+#endif
+GST_DEBUG_CATEGORY_STATIC (gst_base_src_debug);
+#ifndef __SYMBIAN32__
+#define GST_CAT_DEFAULT gst_base_src_debug
+#endif
+
+#define GST_LIVE_GET_LOCK(elem)               (GST_BASE_SRC_CAST(elem)->live_lock)
+#define GST_LIVE_LOCK(elem)                   g_mutex_lock(GST_LIVE_GET_LOCK(elem))
+#define GST_LIVE_TRYLOCK(elem)                g_mutex_trylock(GST_LIVE_GET_LOCK(elem))
+#define GST_LIVE_UNLOCK(elem)                 g_mutex_unlock(GST_LIVE_GET_LOCK(elem))
+#define GST_LIVE_GET_COND(elem)               (GST_BASE_SRC_CAST(elem)->live_cond)
+#define GST_LIVE_WAIT(elem)                   g_cond_wait (GST_LIVE_GET_COND (elem), GST_LIVE_GET_LOCK (elem))
+#define GST_LIVE_TIMED_WAIT(elem, timeval)    g_cond_timed_wait (GST_LIVE_GET_COND (elem), GST_LIVE_GET_LOCK (elem),\
+                                                                                timeval)
+#define GST_LIVE_SIGNAL(elem)                 g_cond_signal (GST_LIVE_GET_COND (elem));
+#define GST_LIVE_BROADCAST(elem)              g_cond_broadcast (GST_LIVE_GET_COND (elem));
+
+/* BaseSrc signals and args */
+enum
+{
+  /* FILL ME */
+  LAST_SIGNAL
+};
+
+#define DEFAULT_BLOCKSIZE       4096
+#define DEFAULT_NUM_BUFFERS     -1
+#define DEFAULT_TYPEFIND	FALSE
+#define DEFAULT_DO_TIMESTAMP	FALSE
+
+enum
+{
+  PROP_0,
+  PROP_BLOCKSIZE,
+  PROP_NUM_BUFFERS,
+  PROP_TYPEFIND,
+  PROP_DO_TIMESTAMP
+};
+
+#define GST_BASE_SRC_GET_PRIVATE(obj)  \
+   (G_TYPE_INSTANCE_GET_PRIVATE ((obj), GST_TYPE_BASE_SRC, GstBaseSrcPrivate))
+
+struct _GstBaseSrcPrivate
+{
+  gboolean last_sent_eos;       /* last thing we did was send an EOS (we set this
+                                 * to avoid the sending of two EOS in some cases) */
+  gboolean discont;
+  gboolean flushing;
+
+  /* two segments to be sent in the streaming thread with STREAM_LOCK */
+  GstEvent *close_segment;
+  GstEvent *start_segment;
+
+  /* if EOS is pending */
+  gboolean pending_eos;
+
+  /* startup latency is the time it takes between going to PLAYING and producing
+   * the first BUFFER with running_time 0. This value is included in the latency
+   * reporting. */
+  GstClockTime latency;
+  /* timestamp offset, this is the offset add to the values of gst_times for
+   * pseudo live sources */
+  GstClockTimeDiff ts_offset;
+
+  gboolean do_timestamp;
+};
+
+static GstElementClass *parent_class = NULL;
+
+static void gst_base_src_base_init (gpointer g_class);
+static void gst_base_src_class_init (GstBaseSrcClass * klass);
+static void gst_base_src_init (GstBaseSrc * src, gpointer g_class);
+static void gst_base_src_finalize (GObject * object);
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+
+
+GType
+gst_base_src_get_type (void)
+{
+  static GType base_src_type = 0;
+
+  if (G_UNLIKELY (base_src_type == 0)) {
+    static const GTypeInfo base_src_info = {
+      sizeof (GstBaseSrcClass),
+      (GBaseInitFunc) gst_base_src_base_init,
+      NULL,
+      (GClassInitFunc) gst_base_src_class_init,
+      NULL,
+      NULL,
+      sizeof (GstBaseSrc),
+      0,
+      (GInstanceInitFunc) gst_base_src_init,
+    };
+
+    base_src_type = g_type_register_static (GST_TYPE_ELEMENT,
+        "GstBaseSrc", &base_src_info, G_TYPE_FLAG_ABSTRACT);
+  }
+  return base_src_type;
+}
+static GstCaps *gst_base_src_getcaps (GstPad * pad);
+static gboolean gst_base_src_setcaps (GstPad * pad, GstCaps * caps);
+static void gst_base_src_fixate (GstPad * pad, GstCaps * caps);
+
+static gboolean gst_base_src_activate_push (GstPad * pad, gboolean active);
+static gboolean gst_base_src_activate_pull (GstPad * pad, gboolean active);
+static void gst_base_src_set_property (GObject * object, guint prop_id,
+    const GValue * value, GParamSpec * pspec);
+static void gst_base_src_get_property (GObject * object, guint prop_id,
+    GValue * value, GParamSpec * pspec);
+static gboolean gst_base_src_event_handler (GstPad * pad, GstEvent * event);
+static gboolean gst_base_src_send_event (GstElement * elem, GstEvent * event);
+static gboolean gst_base_src_default_event (GstBaseSrc * src, GstEvent * event);
+static const GstQueryType *gst_base_src_get_query_types (GstElement * element);
+
+static gboolean gst_base_src_query (GstPad * pad, GstQuery * query);
+
+static gboolean gst_base_src_default_negotiate (GstBaseSrc * basesrc);
+static gboolean gst_base_src_default_do_seek (GstBaseSrc * src,
+    GstSegment * segment);
+static gboolean gst_base_src_default_query (GstBaseSrc * src, GstQuery * query);
+static gboolean gst_base_src_default_prepare_seek_segment (GstBaseSrc * src,
+    GstEvent * event, GstSegment * segment);
+
+static gboolean gst_base_src_set_flushing (GstBaseSrc * basesrc,
+    gboolean flushing, gboolean live_play, gboolean unlock, gboolean * playing);
+static gboolean gst_base_src_start (GstBaseSrc * basesrc);
+static gboolean gst_base_src_stop (GstBaseSrc * basesrc);
+
+static GstStateChangeReturn gst_base_src_change_state (GstElement * element,
+    GstStateChange transition);
+
+static void gst_base_src_loop (GstPad * pad);
+static gboolean gst_base_src_pad_check_get_range (GstPad * pad);
+static gboolean gst_base_src_default_check_get_range (GstBaseSrc * bsrc);
+static GstFlowReturn gst_base_src_pad_get_range (GstPad * pad, guint64 offset,
+    guint length, GstBuffer ** buf);
+static GstFlowReturn gst_base_src_get_range (GstBaseSrc * src, guint64 offset,
+    guint length, GstBuffer ** buf);
+
+static void
+gst_base_src_base_init (gpointer g_class)
+{
+  GST_DEBUG_CATEGORY_INIT (gst_base_src_debug, "basesrc", 0, "basesrc element");
+}
+
+static void
+gst_base_src_class_init (GstBaseSrcClass * klass)
+{
+  GObjectClass *gobject_class;
+  GstElementClass *gstelement_class;
+
+  gobject_class = G_OBJECT_CLASS (klass);
+  gstelement_class = GST_ELEMENT_CLASS (klass);
+
+  g_type_class_add_private (klass, sizeof (GstBaseSrcPrivate));
+
+  parent_class = g_type_class_peek_parent (klass);
+
+  gobject_class->finalize = GST_DEBUG_FUNCPTR (gst_base_src_finalize);
+  gobject_class->set_property = GST_DEBUG_FUNCPTR (gst_base_src_set_property);
+  gobject_class->get_property = GST_DEBUG_FUNCPTR (gst_base_src_get_property);
+
+  g_object_class_install_property (gobject_class, PROP_BLOCKSIZE,
+      g_param_spec_ulong ("blocksize", "Block size",
+          "Size in bytes to read per buffer (0 = default)", 0, G_MAXULONG,
+          DEFAULT_BLOCKSIZE, G_PARAM_READWRITE));
+  g_object_class_install_property (gobject_class, PROP_NUM_BUFFERS,
+      g_param_spec_int ("num-buffers", "num-buffers",
+          "Number of buffers to output before sending EOS", -1, G_MAXINT,
+          DEFAULT_NUM_BUFFERS, G_PARAM_READWRITE));
+  g_object_class_install_property (gobject_class, PROP_TYPEFIND,
+      g_param_spec_boolean ("typefind", "Typefind",
+          "Run typefind before negotiating", DEFAULT_TYPEFIND,
+          G_PARAM_READWRITE));
+  g_object_class_install_property (gobject_class, PROP_DO_TIMESTAMP,
+      g_param_spec_boolean ("do-timestamp", "Do timestamp",
+          "Apply current stream time to buffers", DEFAULT_DO_TIMESTAMP,
+          G_PARAM_READWRITE));
+
+  gstelement_class->change_state =
+      GST_DEBUG_FUNCPTR (gst_base_src_change_state);
+  gstelement_class->send_event = GST_DEBUG_FUNCPTR (gst_base_src_send_event);
+  gstelement_class->get_query_types =
+      GST_DEBUG_FUNCPTR (gst_base_src_get_query_types);
+
+  klass->negotiate = GST_DEBUG_FUNCPTR (gst_base_src_default_negotiate);
+  klass->event = GST_DEBUG_FUNCPTR (gst_base_src_default_event);
+  klass->do_seek = GST_DEBUG_FUNCPTR (gst_base_src_default_do_seek);
+  klass->query = GST_DEBUG_FUNCPTR (gst_base_src_default_query);
+  klass->check_get_range =
+      GST_DEBUG_FUNCPTR (gst_base_src_default_check_get_range);
+  klass->prepare_seek_segment =
+      GST_DEBUG_FUNCPTR (gst_base_src_default_prepare_seek_segment);
+}
+
+static void
+gst_base_src_init (GstBaseSrc * basesrc, gpointer g_class)
+{
+  GstPad *pad;
+  GstPadTemplate *pad_template;
+
+  basesrc->priv = GST_BASE_SRC_GET_PRIVATE (basesrc);
+
+  basesrc->is_live = FALSE;
+  basesrc->live_lock = g_mutex_new ();
+  basesrc->live_cond = g_cond_new ();
+  basesrc->num_buffers = DEFAULT_NUM_BUFFERS;
+  basesrc->num_buffers_left = -1;
+
+  basesrc->can_activate_push = TRUE;
+  basesrc->pad_mode = GST_ACTIVATE_NONE;
+
+  pad_template =
+      gst_element_class_get_pad_template (GST_ELEMENT_CLASS (g_class), "src");
+  g_return_if_fail (pad_template != NULL);
+
+  GST_DEBUG_OBJECT (basesrc, "creating src pad");
+  pad = gst_pad_new_from_template (pad_template, "src");
+
+  GST_DEBUG_OBJECT (basesrc, "setting functions on src pad");
+  gst_pad_set_activatepush_function (pad,
+      GST_DEBUG_FUNCPTR (gst_base_src_activate_push));
+  gst_pad_set_activatepull_function (pad,
+      GST_DEBUG_FUNCPTR (gst_base_src_activate_pull));
+  gst_pad_set_event_function (pad,
+      GST_DEBUG_FUNCPTR (gst_base_src_event_handler));
+  gst_pad_set_query_function (pad, GST_DEBUG_FUNCPTR (gst_base_src_query));
+  gst_pad_set_checkgetrange_function (pad,
+      GST_DEBUG_FUNCPTR (gst_base_src_pad_check_get_range));
+  gst_pad_set_getrange_function (pad,
+      GST_DEBUG_FUNCPTR (gst_base_src_pad_get_range));
+  gst_pad_set_getcaps_function (pad, GST_DEBUG_FUNCPTR (gst_base_src_getcaps));
+  gst_pad_set_setcaps_function (pad, GST_DEBUG_FUNCPTR (gst_base_src_setcaps));
+  gst_pad_set_fixatecaps_function (pad,
+      GST_DEBUG_FUNCPTR (gst_base_src_fixate));
+
+  /* hold pointer to pad */
+  basesrc->srcpad = pad;
+  GST_DEBUG_OBJECT (basesrc, "adding src pad");
+  gst_element_add_pad (GST_ELEMENT (basesrc), pad);
+
+  basesrc->blocksize = DEFAULT_BLOCKSIZE;
+  basesrc->clock_id = NULL;
+  /* we operate in BYTES by default */
+  gst_base_src_set_format (basesrc, GST_FORMAT_BYTES);
+  basesrc->data.ABI.typefind = DEFAULT_TYPEFIND;
+  basesrc->priv->do_timestamp = DEFAULT_DO_TIMESTAMP;
+
+  GST_OBJECT_FLAG_UNSET (basesrc, GST_BASE_SRC_STARTED);
+
+  GST_DEBUG_OBJECT (basesrc, "init done");
+}
+
+static void
+gst_base_src_finalize (GObject * object)
+{
+  GstBaseSrc *basesrc;
+  GstEvent **event_p;
+
+  basesrc = GST_BASE_SRC (object);
+
+  g_mutex_free (basesrc->live_lock);
+  g_cond_free (basesrc->live_cond);
+
+  event_p = &basesrc->data.ABI.pending_seek;
+  gst_event_replace (event_p, NULL);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+/**
+ * gst_base_src_wait_playing:
+ * @src: the src
+ *
+ * If the #GstBaseSrcClass::create method performs its own synchronisation against
+ * the clock it must unblock when going from PLAYING to the PAUSED state and call
+ * this method before continuing to produce the remaining data.
+ *
+ * This function will block until a state change to PLAYING happens (in which
+ * case this function returns #GST_FLOW_OK) or the processing must be stopped due
+ * to a state change to READY or a FLUSH event (in which case this function
+ * returns #GST_FLOW_WRONG_STATE).
+ *
+ * Since: 0.10.12
+ *
+ * Returns: #GST_FLOW_OK if @src is PLAYING and processing can
+ * continue. Any other return value should be returned from the create vmethod.
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+GstFlowReturn
+gst_base_src_wait_playing (GstBaseSrc * src)
+{
+  /* block until the state changes, or we get a flush, or something */
+  GST_DEBUG_OBJECT (src, "live source waiting for running state");
+  GST_LIVE_WAIT (src);
+  if (src->priv->flushing)
+    goto flushing;
+  GST_DEBUG_OBJECT (src, "live source unlocked");
+
+  return GST_FLOW_OK;
+
+  /* ERRORS */
+flushing:
+  {
+    GST_DEBUG_OBJECT (src, "we are flushing");
+    return GST_FLOW_WRONG_STATE;
+  }
+}
+
+/**
+ * gst_base_src_set_live:
+ * @src: base source instance
+ * @live: new live-mode
+ *
+ * If the element listens to a live source, @live should
+ * be set to %TRUE. 
+ *
+ * A live source will not produce data in the PAUSED state and
+ * will therefore not be able to participate in the PREROLL phase
+ * of a pipeline. To signal this fact to the application and the 
+ * pipeline, the state change return value of the live source will
+ * be GST_STATE_CHANGE_NO_PREROLL.
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+void
+gst_base_src_set_live (GstBaseSrc * src, gboolean live)
+{
+  GST_OBJECT_LOCK (src);
+  src->is_live = live;
+  GST_OBJECT_UNLOCK (src);
+}
+
+/**
+ * gst_base_src_is_live:
+ * @src: base source instance
+ *
+ * Check if an element is in live mode.
+ *
+ * Returns: %TRUE if element is in live mode.
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+gboolean
+gst_base_src_is_live (GstBaseSrc * src)
+{
+  gboolean result;
+
+  GST_OBJECT_LOCK (src);
+  result = src->is_live;
+  GST_OBJECT_UNLOCK (src);
+
+  return result;
+}
+
+/**
+ * gst_base_src_set_format:
+ * @src: base source instance
+ * @format: the format to use
+ *
+ * Sets the default format of the source. This will be the format used
+ * for sending NEW_SEGMENT events and for performing seeks.
+ *
+ * If a format of GST_FORMAT_BYTES is set, the element will be able to
+ * operate in pull mode if the #GstBaseSrc::is_seekable returns TRUE.
+ *
+ * Since: 0.10.1
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+void
+gst_base_src_set_format (GstBaseSrc * src, GstFormat format)
+{
+  gst_segment_init (&src->segment, format);
+}
+
+/**
+ * gst_base_src_query_latency:
+ * @src: the source
+ * @live: if the source is live
+ * @min_latency: the min latency of the source
+ * @max_latency: the max latency of the source
+ *
+ * Query the source for the latency parameters. @live will be TRUE when @src is
+ * configured as a live source. @min_latency will be set to the difference
+ * between the running time and the timestamp of the first buffer.
+ * @max_latency is always the undefined value of -1.
+ *
+ * This function is mostly used by subclasses. 
+ *
+ * Returns: TRUE if the query succeeded.
+ *
+ * Since: 0.10.13
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+gboolean
+gst_base_src_query_latency (GstBaseSrc * src, gboolean * live,
+    GstClockTime * min_latency, GstClockTime * max_latency)
+{
+  GstClockTime min;
+
+  GST_OBJECT_LOCK (src);
+  if (live)
+    *live = src->is_live;
+
+  /* if we have a startup latency, report this one, else report 0. Subclasses
+   * are supposed to override the query function if they want something
+   * else. */
+  if (src->priv->latency != -1)
+    min = src->priv->latency;
+  else
+    min = 0;
+
+  if (min_latency)
+    *min_latency = min;
+  if (max_latency)
+    *max_latency = -1;
+
+  GST_LOG_OBJECT (src, "latency: live %d, min %" GST_TIME_FORMAT
+      ", max %" GST_TIME_FORMAT, src->is_live, GST_TIME_ARGS (min),
+      GST_TIME_ARGS (-1));
+  GST_OBJECT_UNLOCK (src);
+
+  return TRUE;
+}
+
+/**
+ * gst_base_src_set_do_timestamp:
+ * @src: the source
+ * @timestamp: enable or disable timestamping
+ *
+ * Configure @src to automatically timestamp outgoing buffers based on the
+ * current running_time of the pipeline. This property is mostly useful for live
+ * sources.
+ *
+ * Since: 0.10.15
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+void
+gst_base_src_set_do_timestamp (GstBaseSrc * src, gboolean timestamp)
+{
+  GST_OBJECT_LOCK (src);
+  src->priv->do_timestamp = timestamp;
+  GST_OBJECT_UNLOCK (src);
+}
+
+/**
+ * gst_base_src_get_do_timestamp:
+ * @src: the source
+ *
+ * Query if @src timestamps outgoing buffers based on the current running_time.
+ *
+ * Returns: %TRUE if the base class will automatically timestamp outgoing buffers.
+ *
+ * Since: 0.10.15
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+gboolean
+gst_base_src_get_do_timestamp (GstBaseSrc * src)
+{
+  gboolean res;
+
+  GST_OBJECT_LOCK (src);
+  res = src->priv->do_timestamp;
+  GST_OBJECT_UNLOCK (src);
+
+  return res;
+}
+
+static gboolean
+gst_base_src_setcaps (GstPad * pad, GstCaps * caps)
+{
+  GstBaseSrcClass *bclass;
+  GstBaseSrc *bsrc;
+  gboolean res = TRUE;
+
+  bsrc = GST_BASE_SRC (GST_PAD_PARENT (pad));
+  bclass = GST_BASE_SRC_GET_CLASS (bsrc);
+
+  if (bclass->set_caps)
+    res = bclass->set_caps (bsrc, caps);
+
+  return res;
+}
+
+static GstCaps *
+gst_base_src_getcaps (GstPad * pad)
+{
+  GstBaseSrcClass *bclass;
+  GstBaseSrc *bsrc;
+  GstCaps *caps = NULL;
+
+  bsrc = GST_BASE_SRC (GST_PAD_PARENT (pad));
+  bclass = GST_BASE_SRC_GET_CLASS (bsrc);
+  if (bclass->get_caps)
+    caps = bclass->get_caps (bsrc);
+
+  if (caps == NULL) {
+    GstPadTemplate *pad_template;
+
+    pad_template =
+        gst_element_class_get_pad_template (GST_ELEMENT_CLASS (bclass), "src");
+    if (pad_template != NULL) {
+      caps = gst_caps_ref (gst_pad_template_get_caps (pad_template));
+    }
+  }
+  return caps;
+}
+
+static void
+gst_base_src_fixate (GstPad * pad, GstCaps * caps)
+{
+  GstBaseSrcClass *bclass;
+  GstBaseSrc *bsrc;
+
+  bsrc = GST_BASE_SRC (gst_pad_get_parent (pad));
+  bclass = GST_BASE_SRC_GET_CLASS (bsrc);
+
+  if (bclass->fixate)
+    bclass->fixate (bsrc, caps);
+
+  gst_object_unref (bsrc);
+}
+
+static gboolean
+gst_base_src_default_query (GstBaseSrc * src, GstQuery * query)
+{
+  gboolean res;
+
+  switch (GST_QUERY_TYPE (query)) {
+    case GST_QUERY_POSITION:
+    {
+      GstFormat format;
+
+      gst_query_parse_position (query, &format, NULL);
+      switch (format) {
+        case GST_FORMAT_PERCENT:
+        {
+          gint64 percent;
+          gint64 position;
+          gint64 duration;
+
+          position = src->segment.last_stop;
+          duration = src->segment.duration;
+
+          if (position != -1 && duration != -1) {
+            if (position < duration)
+              percent = gst_util_uint64_scale (GST_FORMAT_PERCENT_MAX, position,
+                  duration);
+            else
+              percent = GST_FORMAT_PERCENT_MAX;
+          } else
+            percent = -1;
+
+          gst_query_set_position (query, GST_FORMAT_PERCENT, percent);
+          res = TRUE;
+          break;
+        }
+        default:
+        {
+          gint64 position;
+
+          position = src->segment.last_stop;
+
+          if (position != -1) {
+            /* convert to requested format */
+            res =
+                gst_pad_query_convert (src->srcpad, src->segment.format,
+                position, &format, &position);
+          } else
+            res = TRUE;
+
+          gst_query_set_position (query, format, position);
+          break;
+        }
+      }
+      break;
+    }
+    case GST_QUERY_DURATION:
+    {
+      GstFormat format;
+
+      gst_query_parse_duration (query, &format, NULL);
+
+      GST_DEBUG_OBJECT (src, "duration query in format %s",
+          gst_format_get_name (format));
+      switch (format) {
+        case GST_FORMAT_PERCENT:
+          gst_query_set_duration (query, GST_FORMAT_PERCENT,
+              GST_FORMAT_PERCENT_MAX);
+          res = TRUE;
+          break;
+        default:
+        {
+          gint64 duration;
+
+          /* this is the duration as configured by the subclass. */
+          duration = src->segment.duration;
+
+          if (duration != -1) {
+            /* convert to requested format, if this fails, we have a duration
+             * but we cannot answer the query, we must return FALSE. */
+            res =
+                gst_pad_query_convert (src->srcpad, src->segment.format,
+                duration, &format, &duration);
+          } else {
+            /* The subclass did not configure a duration, we assume that the
+             * media has an unknown duration then and we return TRUE to report
+             * this. Note that this is not the same as returning FALSE, which
+             * means that we cannot report the duration at all. */
+            res = TRUE;
+          }
+          gst_query_set_duration (query, format, duration);
+          break;
+        }
+      }
+      break;
+    }
+
+    case GST_QUERY_SEEKING:
+    {
+      gst_query_set_seeking (query, src->segment.format,
+          src->seekable, 0, src->segment.duration);
+      res = TRUE;
+      break;
+    }
+    case GST_QUERY_SEGMENT:
+    {
+      gint64 start, stop;
+
+      /* no end segment configured, current duration then */
+      if ((stop = src->segment.stop) == -1)
+        stop = src->segment.duration;
+      start = src->segment.start;
+
+      /* adjust to stream time */
+      if (src->segment.time != -1) {
+        start -= src->segment.time;
+        if (stop != -1)
+          stop -= src->segment.time;
+      }
+      gst_query_set_segment (query, src->segment.rate, src->segment.format,
+          start, stop);
+      res = TRUE;
+      break;
+    }
+
+    case GST_QUERY_FORMATS:
+    {
+      gst_query_set_formats (query, 3, GST_FORMAT_DEFAULT,
+          GST_FORMAT_BYTES, GST_FORMAT_PERCENT);
+      res = TRUE;
+      break;
+    }
+    case GST_QUERY_CONVERT:
+    {
+      GstFormat src_fmt, dest_fmt;
+      gint64 src_val, dest_val;
+
+      gst_query_parse_convert (query, &src_fmt, &src_val, &dest_fmt, &dest_val);
+
+      /* we can only convert between equal formats... */
+      if (src_fmt == dest_fmt) {
+        dest_val = src_val;
+        res = TRUE;
+      } else
+        res = FALSE;
+
+      gst_query_set_convert (query, src_fmt, src_val, dest_fmt, dest_val);
+      break;
+    }
+    case GST_QUERY_LATENCY:
+    {
+      GstClockTime min, max;
+      gboolean live;
+
+      /* Subclasses should override and implement something usefull */
+      res = gst_base_src_query_latency (src, &live, &min, &max);
+
+      GST_LOG_OBJECT (src, "report latency: live %d, min %" GST_TIME_FORMAT
+          ", max %" GST_TIME_FORMAT, live, GST_TIME_ARGS (min),
+          GST_TIME_ARGS (max));
+
+      gst_query_set_latency (query, live, min, max);
+      break;
+    }
+    case GST_QUERY_JITTER:
+    case GST_QUERY_RATE:
+    default:
+      res = FALSE;
+      break;
+  }
+  GST_DEBUG_OBJECT (src, "query %s returns %d", GST_QUERY_TYPE_NAME (query),
+      res);
+  return res;
+}
+
+static gboolean
+gst_base_src_query (GstPad * pad, GstQuery * query)
+{
+  GstBaseSrc *src;
+  GstBaseSrcClass *bclass;
+  gboolean result = FALSE;
+
+  src = GST_BASE_SRC (gst_pad_get_parent (pad));
+
+  bclass = GST_BASE_SRC_GET_CLASS (src);
+
+  if (bclass->query)
+    result = bclass->query (src, query);
+  else
+    result = gst_pad_query_default (pad, query);
+
+  gst_object_unref (src);
+
+  return result;
+}
+
+static gboolean
+gst_base_src_default_do_seek (GstBaseSrc * src, GstSegment * segment)
+{
+  gboolean res = TRUE;
+
+  /* update our offset if the start/stop position was updated */
+  if (segment->format == GST_FORMAT_BYTES) {
+    segment->time = segment->start;
+  } else if (segment->start == 0) {
+    /* seek to start, we can implement a default for this. */
+    segment->time = 0;
+    res = TRUE;
+  } else
+    res = FALSE;
+
+  return res;
+}
+
+static gboolean
+gst_base_src_do_seek (GstBaseSrc * src, GstSegment * segment)
+{
+  GstBaseSrcClass *bclass;
+  gboolean result = FALSE;
+
+  bclass = GST_BASE_SRC_GET_CLASS (src);
+
+  if (bclass->do_seek)
+    result = bclass->do_seek (src, segment);
+
+  return result;
+}
+
+#define SEEK_TYPE_IS_RELATIVE(t) (((t) != GST_SEEK_TYPE_NONE) && ((t) != GST_SEEK_TYPE_SET))
+
+static gboolean
+gst_base_src_default_prepare_seek_segment (GstBaseSrc * src, GstEvent * event,
+    GstSegment * segment)
+{
+  /* By default, we try one of 2 things:
+   *   - For absolute seek positions, convert the requested position to our 
+   *     configured processing format and place it in the output segment \
+   *   - For relative seek positions, convert our current (input) values to the
+   *     seek format, adjust by the relative seek offset and then convert back to
+   *     the processing format
+   */
+  GstSeekType cur_type, stop_type;
+  gint64 cur, stop;
+  GstSeekFlags flags;
+  GstFormat seek_format, dest_format;
+  gdouble rate;
+  gboolean update;
+  gboolean res = TRUE;
+
+  gst_event_parse_seek (event, &rate, &seek_format, &flags,
+      &cur_type, &cur, &stop_type, &stop);
+  dest_format = segment->format;
+
+  if (seek_format == dest_format) {
+    gst_segment_set_seek (segment, rate, seek_format, flags,
+        cur_type, cur, stop_type, stop, &update);
+    return TRUE;
+  }
+
+  if (cur_type != GST_SEEK_TYPE_NONE) {
+    /* FIXME: Handle seek_cur & seek_end by converting the input segment vals */
+    res =
+        gst_pad_query_convert (src->srcpad, seek_format, cur, &dest_format,
+        &cur);
+    cur_type = GST_SEEK_TYPE_SET;
+  }
+
+  if (res && stop_type != GST_SEEK_TYPE_NONE) {
+    /* FIXME: Handle seek_cur & seek_end by converting the input segment vals */
+    res =
+        gst_pad_query_convert (src->srcpad, seek_format, stop, &dest_format,
+        &stop);
+    stop_type = GST_SEEK_TYPE_SET;
+  }
+
+  /* And finally, configure our output segment in the desired format */
+  gst_segment_set_seek (segment, rate, dest_format, flags, cur_type, cur,
+      stop_type, stop, &update);
+
+  if (!res)
+    goto no_format;
+
+  return res;
+
+no_format:
+  {
+    GST_DEBUG_OBJECT (src, "undefined format given, seek aborted.");
+    return FALSE;
+  }
+}
+
+static gboolean
+gst_base_src_prepare_seek_segment (GstBaseSrc * src, GstEvent * event,
+    GstSegment * seeksegment)
+{
+  GstBaseSrcClass *bclass;
+  gboolean result = FALSE;
+
+  bclass = GST_BASE_SRC_GET_CLASS (src);
+
+  if (bclass->prepare_seek_segment)
+    result = bclass->prepare_seek_segment (src, event, seeksegment);
+
+  return result;
+}
+
+/* this code implements the seeking. It is a good example
+ * handling all cases.
+ *
+ * A seek updates the currently configured segment.start
+ * and segment.stop values based on the SEEK_TYPE. If the
+ * segment.start value is updated, a seek to this new position
+ * should be performed.
+ *
+ * The seek can only be executed when we are not currently
+ * streaming any data, to make sure that this is the case, we
+ * acquire the STREAM_LOCK which is taken when we are in the
+ * _loop() function or when a getrange() is called. Normally
+ * we will not receive a seek if we are operating in pull mode
+ * though. When we operate as a live source we might block on the live
+ * cond, which does not release the STREAM_LOCK. Therefore we will try
+ * to grab the LIVE_LOCK instead of the STREAM_LOCK to make sure it is
+ * safe to perform the seek.
+ *
+ * When we are in the loop() function, we might be in the middle
+ * of pushing a buffer, which might block in a sink. To make sure
+ * that the push gets unblocked we push out a FLUSH_START event.
+ * Our loop function will get a WRONG_STATE return value from
+ * the push and will pause, effectively releasing the STREAM_LOCK.
+ *
+ * For a non-flushing seek, we pause the task, which might eventually
+ * release the STREAM_LOCK. We say eventually because when the sink
+ * blocks on the sample we might wait a very long time until the sink
+ * unblocks the sample. In any case we acquire the STREAM_LOCK and
+ * can continue the seek. A non-flushing seek is normally done in a 
+ * running pipeline to perform seamless playback, this means that the sink is
+ * PLAYING and will return from its chain function.
+ * In the case of a non-flushing seek we need to make sure that the
+ * data we output after the seek is continuous with the previous data,
+ * this is because a non-flushing seek does not reset the running-time
+ * to 0. We do this by closing the currently running segment, ie. sending
+ * a new_segment event with the stop position set to the last processed 
+ * position.
+ *
+ * After updating the segment.start/stop values, we prepare for
+ * streaming again. We push out a FLUSH_STOP to make the peer pad
+ * accept data again and we start our task again.
+ *
+ * A segment seek posts a message on the bus saying that the playback
+ * of the segment started. We store the segment flag internally because
+ * when we reach the segment.stop we have to post a segment.done
+ * instead of EOS when doing a segment seek.
+ */
+/* FIXME (0.11), we have the unlock gboolean here because most current 
+ * implementations (fdsrc, -base/gst/tcp/, ...) unconditionally unlock, even when
+ * the streaming thread isn't running, resulting in bogus unlocks later when it 
+ * starts. This is fixed by adding unlock_stop, but we should still avoid unlocking
+ * unnecessarily for backwards compatibility. Ergo, the unlock variable stays
+ * until 0.11
+ */
+static gboolean
+gst_base_src_perform_seek (GstBaseSrc * src, GstEvent * event, gboolean unlock)
+{
+  gboolean res = TRUE;
+  gdouble rate;
+  GstFormat seek_format, dest_format;
+  GstSeekFlags flags;
+  GstSeekType cur_type, stop_type;
+  gint64 cur, stop;
+  gboolean flush, playing;
+  gboolean update;
+  gboolean relative_seek = FALSE;
+  gboolean seekseg_configured = FALSE;
+  GstSegment seeksegment;
+
+  GST_DEBUG_OBJECT (src, "doing seek");
+
+  dest_format = src->segment.format;
+
+  if (event) {
+    gst_event_parse_seek (event, &rate, &seek_format, &flags,
+        &cur_type, &cur, &stop_type, &stop);
+
+    relative_seek = SEEK_TYPE_IS_RELATIVE (cur_type) ||
+        SEEK_TYPE_IS_RELATIVE (stop_type);
+
+    if (dest_format != seek_format && !relative_seek) {
+      /* If we have an ABSOLUTE position (SEEK_SET only), we can convert it
+       * here before taking the stream lock, otherwise we must convert it later,
+       * once we have the stream lock and can read the current position */
+      gst_segment_init (&seeksegment, dest_format);
+
+      if (!gst_base_src_prepare_seek_segment (src, event, &seeksegment))
+        goto prepare_failed;
+
+      seekseg_configured = TRUE;
+    }
+
+    flush = flags & GST_SEEK_FLAG_FLUSH;
+  } else {
+    flush = FALSE;
+  }
+
+  /* send flush start */
+  if (flush)
+    gst_pad_push_event (src->srcpad, gst_event_new_flush_start ());
+  else
+    gst_pad_pause_task (src->srcpad);
+
+  /* unblock streaming thread. */
+  gst_base_src_set_flushing (src, TRUE, FALSE, unlock, &playing);
+
+  /* grab streaming lock, this should eventually be possible, either
+   * because the task is paused, our streaming thread stopped 
+   * or because our peer is flushing. */
+  GST_PAD_STREAM_LOCK (src->srcpad);
+
+  gst_base_src_set_flushing (src, FALSE, playing, unlock, NULL);
+
+  /* If we configured the seeksegment above, don't overwrite it now. Otherwise
+   * copy the current segment info into the temp segment that we can actually
+   * attempt the seek with. We only update the real segment if the seek suceeds. */
+  if (!seekseg_configured) {
+    memcpy (&seeksegment, &src->segment, sizeof (GstSegment));
+
+    /* now configure the final seek segment */
+    if (event) {
+      if (src->segment.format != seek_format) {
+        /* OK, here's where we give the subclass a chance to convert the relative
+         * seek into an absolute one in the processing format. We set up any
+         * absolute seek above, before taking the stream lock. */
+        if (!gst_base_src_prepare_seek_segment (src, event, &seeksegment)) {
+          GST_DEBUG_OBJECT (src, "Preparing the seek failed after flushing. "
+              "Aborting seek");
+          res = FALSE;
+        }
+      } else {
+        /* The seek format matches our processing format, no need to ask the
+         * the subclass to configure the segment. */
+        gst_segment_set_seek (&seeksegment, rate, seek_format, flags,
+            cur_type, cur, stop_type, stop, &update);
+      }
+    }
+    /* Else, no seek event passed, so we're just (re)starting the 
+       current segment. */
+  }
+
+  if (res) {
+    GST_DEBUG_OBJECT (src, "segment configured from %" G_GINT64_FORMAT
+        " to %" G_GINT64_FORMAT ", position %" G_GINT64_FORMAT,
+        seeksegment.start, seeksegment.stop, seeksegment.last_stop);
+
+    /* do the seek, segment.last_stop contains the new position. */
+    res = gst_base_src_do_seek (src, &seeksegment);
+  }
+
+  /* and prepare to continue streaming */
+  if (flush) {
+    /* send flush stop, peer will accept data and events again. We
+     * are not yet providing data as we still have the STREAM_LOCK. */
+    gst_pad_push_event (src->srcpad, gst_event_new_flush_stop ());
+  } else if (res && src->data.ABI.running) {
+    /* we are running the current segment and doing a non-flushing seek, 
+     * close the segment first based on the last_stop. */
+    GST_DEBUG_OBJECT (src, "closing running segment %" G_GINT64_FORMAT
+        " to %" G_GINT64_FORMAT, src->segment.start, src->segment.last_stop);
+
+    /* queue the segment for sending in the stream thread */
+    if (src->priv->close_segment)
+      gst_event_unref (src->priv->close_segment);
+    src->priv->close_segment =
+        gst_event_new_new_segment_full (TRUE,
+        src->segment.rate, src->segment.applied_rate, src->segment.format,
+        src->segment.start, src->segment.last_stop, src->segment.time);
+  }
+
+  /* The subclass must have converted the segment to the processing format 
+   * by now */
+  if (res && seeksegment.format != dest_format) {
+    GST_DEBUG_OBJECT (src, "Subclass failed to prepare a seek segment "
+        "in the correct format. Aborting seek.");
+    res = FALSE;
+  }
+
+  /* if successfull seek, we update our real segment and push
+   * out the new segment. */
+  if (res) {
+    memcpy (&src->segment, &seeksegment, sizeof (GstSegment));
+
+    if (src->segment.flags & GST_SEEK_FLAG_SEGMENT) {
+      gst_element_post_message (GST_ELEMENT (src),
+          gst_message_new_segment_start (GST_OBJECT (src),
+              src->segment.format, src->segment.last_stop));
+    }
+
+    /* for deriving a stop position for the playback segment from the seek
+     * segment, we must take the duration when the stop is not set */
+    if ((stop = src->segment.stop) == -1)
+      stop = src->segment.duration;
+
+    GST_DEBUG_OBJECT (src, "Sending newsegment from %" G_GINT64_FORMAT
+        " to %" G_GINT64_FORMAT, src->segment.start, stop);
+
+    /* now replace the old segment so that we send it in the stream thread the
+     * next time it is scheduled. */
+    if (src->priv->start_segment)
+      gst_event_unref (src->priv->start_segment);
+    if (src->segment.rate >= 0.0) {
+      /* forward, we send data from last_stop to stop */
+      src->priv->start_segment =
+          gst_event_new_new_segment_full (FALSE,
+          src->segment.rate, src->segment.applied_rate, src->segment.format,
+          src->segment.last_stop, stop, src->segment.time);
+    } else {
+      /* reverse, we send data from stop to last_stop */
+      src->priv->start_segment =
+          gst_event_new_new_segment_full (FALSE,
+          src->segment.rate, src->segment.applied_rate, src->segment.format,
+          src->segment.start, src->segment.last_stop, src->segment.time);
+    }
+  }
+
+  src->priv->discont = TRUE;
+  src->data.ABI.running = TRUE;
+  /* and restart the task in case it got paused explicitely or by
+   * the FLUSH_START event we pushed out. */
+  gst_pad_start_task (src->srcpad, (GstTaskFunction) gst_base_src_loop,
+      src->srcpad);
+
+  /* and release the lock again so we can continue streaming */
+  GST_PAD_STREAM_UNLOCK (src->srcpad);
+
+  return res;
+
+  /* ERROR */
+prepare_failed:
+  GST_DEBUG_OBJECT (src, "Preparing the seek failed before flushing. "
+      "Aborting seek");
+  return FALSE;
+}
+
+static const GstQueryType *
+gst_base_src_get_query_types (GstElement * element)
+{
+  static const GstQueryType query_types[] = {
+    GST_QUERY_DURATION,
+    GST_QUERY_POSITION,
+    GST_QUERY_SEEKING,
+    GST_QUERY_SEGMENT,
+    GST_QUERY_FORMATS,
+    GST_QUERY_LATENCY,
+    GST_QUERY_JITTER,
+    GST_QUERY_RATE,
+    GST_QUERY_CONVERT,
+    0
+  };
+
+  return query_types;
+}
+
+/* all events send to this element directly. This is mainly done from the
+ * application.
+ */
+static gboolean
+gst_base_src_send_event (GstElement * element, GstEvent * event)
+{
+  GstBaseSrc *src;
+  gboolean result = FALSE;
+
+  src = GST_BASE_SRC (element);
+
+  switch (GST_EVENT_TYPE (event)) {
+      /* bidirectional events */
+    case GST_EVENT_FLUSH_START:
+    case GST_EVENT_FLUSH_STOP:
+      /* sending random flushes downstream can break stuff,
+       * especially sync since all segment info will get flushed */
+      break;
+
+      /* downstream serialized events */
+    case GST_EVENT_EOS:
+      /* queue EOS and make sure the task or pull function 
+       * performs the EOS actions. */
+      GST_LIVE_LOCK (src);
+      src->priv->pending_eos = TRUE;
+      GST_LIVE_UNLOCK (src);
+      result = TRUE;
+      break;
+    case GST_EVENT_NEWSEGMENT:
+      /* sending random NEWSEGMENT downstream can break sync. */
+      break;
+    case GST_EVENT_TAG:
+      /* sending tags could be useful, FIXME insert in dataflow */
+      break;
+    case GST_EVENT_BUFFERSIZE:
+      /* does not seem to make much sense currently */
+      break;
+
+      /* upstream events */
+    case GST_EVENT_QOS:
+      /* elements should override send_event and do something */
+      break;
+    case GST_EVENT_SEEK:
+    {
+      gboolean started;
+
+      GST_OBJECT_LOCK (src->srcpad);
+      if (GST_PAD_ACTIVATE_MODE (src->srcpad) == GST_ACTIVATE_PULL)
+        goto wrong_mode;
+      started = GST_PAD_ACTIVATE_MODE (src->srcpad) == GST_ACTIVATE_PUSH;
+      GST_OBJECT_UNLOCK (src->srcpad);
+
+      if (started) {
+        /* when we are running in push mode, we can execute the
+         * seek right now, we need to unlock. */
+        result = gst_base_src_perform_seek (src, event, TRUE);
+      } else {
+        GstEvent **event_p;
+
+        /* else we store the event and execute the seek when we
+         * get activated */
+        GST_OBJECT_LOCK (src);
+        event_p = &src->data.ABI.pending_seek;
+        gst_event_replace ((GstEvent **) event_p, event);
+        GST_OBJECT_UNLOCK (src);
+        /* assume the seek will work */
+        result = TRUE;
+      }
+      break;
+    }
+    case GST_EVENT_NAVIGATION:
+      /* could make sense for elements that do something with navigation events
+       * but then they would need to override the send_event function */
+      break;
+    case GST_EVENT_LATENCY:
+      /* does not seem to make sense currently */
+      break;
+
+      /* custom events */
+    case GST_EVENT_CUSTOM_UPSTREAM:
+      /* override send_event if you want this */
+      break;
+    case GST_EVENT_CUSTOM_DOWNSTREAM:
+    case GST_EVENT_CUSTOM_BOTH:
+      /* FIXME, insert event in the dataflow */
+      break;
+    case GST_EVENT_CUSTOM_DOWNSTREAM_OOB:
+    case GST_EVENT_CUSTOM_BOTH_OOB:
+      /* insert a random custom event into the pipeline */
+      GST_DEBUG_OBJECT (src, "pushing custom OOB event downstream");
+      result = gst_pad_push_event (src->srcpad, event);
+      /* we gave away the ref to the event in the push */
+      event = NULL;
+      break;
+    default:
+      break;
+  }
+done:
+  /* if we still have a ref to the event, unref it now */
+  if (event)
+    gst_event_unref (event);
+
+  return result;
+
+  /* ERRORS */
+wrong_mode:
+  {
+    GST_DEBUG_OBJECT (src, "cannot perform seek when operating in pull mode");
+    GST_OBJECT_UNLOCK (src->srcpad);
+    result = FALSE;
+    goto done;
+  }
+}
+
+static gboolean
+gst_base_src_default_event (GstBaseSrc * src, GstEvent * event)
+{
+  gboolean result;
+
+  switch (GST_EVENT_TYPE (event)) {
+    case GST_EVENT_SEEK:
+      /* is normally called when in push mode */
+      if (!src->seekable)
+        goto not_seekable;
+
+      result = gst_base_src_perform_seek (src, event, TRUE);
+      break;
+    case GST_EVENT_FLUSH_START:
+      /* cancel any blocking getrange, is normally called
+       * when in pull mode. */
+      result = gst_base_src_set_flushing (src, TRUE, FALSE, TRUE, NULL);
+      break;
+    case GST_EVENT_FLUSH_STOP:
+      result = gst_base_src_set_flushing (src, FALSE, TRUE, TRUE, NULL);
+      break;
+    default:
+      result = TRUE;
+      break;
+  }
+  return result;
+
+  /* ERRORS */
+not_seekable:
+  {
+    GST_DEBUG_OBJECT (src, "is not seekable");
+    return FALSE;
+  }
+}
+
+static gboolean
+gst_base_src_event_handler (GstPad * pad, GstEvent * event)
+{
+  GstBaseSrc *src;
+  GstBaseSrcClass *bclass;
+  gboolean result = FALSE;
+
+  src = GST_BASE_SRC (gst_pad_get_parent (pad));
+  bclass = GST_BASE_SRC_GET_CLASS (src);
+
+  if (bclass->event) {
+    if (!(result = bclass->event (src, event)))
+      goto subclass_failed;
+  }
+
+done:
+  gst_event_unref (event);
+  gst_object_unref (src);
+
+  return result;
+
+  /* ERRORS */
+subclass_failed:
+  {
+    GST_DEBUG_OBJECT (src, "subclass refused event");
+    goto done;
+  }
+}
+
+static void
+gst_base_src_set_property (GObject * object, guint prop_id,
+    const GValue * value, GParamSpec * pspec)
+{
+  GstBaseSrc *src;
+
+  src = GST_BASE_SRC (object);
+
+  switch (prop_id) {
+    case PROP_BLOCKSIZE:
+      src->blocksize = g_value_get_ulong (value);
+      break;
+    case PROP_NUM_BUFFERS:
+      src->num_buffers = g_value_get_int (value);
+      break;
+    case PROP_TYPEFIND:
+      src->data.ABI.typefind = g_value_get_boolean (value);
+      break;
+    case PROP_DO_TIMESTAMP:
+      src->priv->do_timestamp = g_value_get_boolean (value);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+  }
+}
+
+static void
+gst_base_src_get_property (GObject * object, guint prop_id, GValue * value,
+    GParamSpec * pspec)
+{
+  GstBaseSrc *src;
+
+  src = GST_BASE_SRC (object);
+
+  switch (prop_id) {
+    case PROP_BLOCKSIZE:
+      g_value_set_ulong (value, src->blocksize);
+      break;
+    case PROP_NUM_BUFFERS:
+      g_value_set_int (value, src->num_buffers);
+      break;
+    case PROP_TYPEFIND:
+      g_value_set_boolean (value, src->data.ABI.typefind);
+      break;
+    case PROP_DO_TIMESTAMP:
+      g_value_set_boolean (value, src->priv->do_timestamp);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+  }
+}
+
+/* with STREAM_LOCK and LOCK */
+static GstClockReturn
+gst_base_src_wait (GstBaseSrc * basesrc, GstClock * clock, GstClockTime time)
+{
+  GstClockReturn ret;
+  GstClockID id;
+
+  id = gst_clock_new_single_shot_id (clock, time);
+
+  basesrc->clock_id = id;
+  /* release the live lock while waiting */
+  GST_LIVE_UNLOCK (basesrc);
+
+  ret = gst_clock_id_wait (id, NULL);
+
+  GST_LIVE_LOCK (basesrc);
+  gst_clock_id_unref (id);
+  basesrc->clock_id = NULL;
+
+  return ret;
+}
+
+/* perform synchronisation on a buffer. 
+ * with STREAM_LOCK.
+ */
+static GstClockReturn
+gst_base_src_do_sync (GstBaseSrc * basesrc, GstBuffer * buffer)
+{
+  GstClockReturn result;
+  GstClockTime start, end;
+  GstBaseSrcClass *bclass;
+  GstClockTime base_time;
+  GstClock *clock;
+  GstClockTime now = GST_CLOCK_TIME_NONE, timestamp;
+  gboolean do_timestamp, first, pseudo_live;
+
+  bclass = GST_BASE_SRC_GET_CLASS (basesrc);
+
+  start = end = -1;
+  if (bclass->get_times)
+    bclass->get_times (basesrc, buffer, &start, &end);
+
+  /* get buffer timestamp */
+  timestamp = GST_BUFFER_TIMESTAMP (buffer);
+
+  /* grab the lock to prepare for clocking and calculate the startup 
+   * latency. */
+  GST_OBJECT_LOCK (basesrc);
+
+  /* if we are asked to sync against the clock we are a pseudo live element */
+  pseudo_live = (start != -1 && basesrc->is_live);
+  /* check for the first buffer */
+  first = (basesrc->priv->latency == -1);
+
+  if (timestamp != -1 && pseudo_live) {
+    GstClockTime latency;
+
+    /* we have a timestamp and a sync time, latency is the diff */
+    if (timestamp <= start)
+      latency = start - timestamp;
+    else
+      latency = 0;
+
+    if (first) {
+      GST_DEBUG_OBJECT (basesrc, "pseudo_live with latency %" GST_TIME_FORMAT,
+          GST_TIME_ARGS (latency));
+      /* first time we calculate latency, just configure */
+      basesrc->priv->latency = latency;
+    } else {
+      if (basesrc->priv->latency != latency) {
+        /* we have a new latency, FIXME post latency message */
+        basesrc->priv->latency = latency;
+        GST_DEBUG_OBJECT (basesrc, "latency changed to %" GST_TIME_FORMAT,
+            GST_TIME_ARGS (latency));
+      }
+    }
+  } else if (first) {
+    GST_DEBUG_OBJECT (basesrc, "no latency needed, live %d, sync %d",
+        basesrc->is_live, start != -1);
+    basesrc->priv->latency = 0;
+  }
+
+  /* get clock, if no clock, we can't sync or do timestamps */
+  if ((clock = GST_ELEMENT_CLOCK (basesrc)) == NULL)
+    goto no_clock;
+
+  base_time = GST_ELEMENT_CAST (basesrc)->base_time;
+
+  do_timestamp = basesrc->priv->do_timestamp;
+
+  /* first buffer, calculate the timestamp offset */
+  if (first) {
+    GstClockTime running_time;
+
+    now = gst_clock_get_time (clock);
+    running_time = now - base_time;
+
+    GST_LOG_OBJECT (basesrc,
+        "startup timestamp: %" GST_TIME_FORMAT ", running_time %"
+        GST_TIME_FORMAT, GST_TIME_ARGS (timestamp),
+        GST_TIME_ARGS (running_time));
+
+    if (pseudo_live && timestamp != -1) {
+      /* live source and we need to sync, add startup latency to all timestamps
+       * to get the real running_time. Live sources should always timestamp
+       * according to the current running time. */
+      basesrc->priv->ts_offset = GST_CLOCK_DIFF (timestamp, running_time);
+
+      GST_LOG_OBJECT (basesrc, "live with sync, ts_offset %" GST_TIME_FORMAT,
+          GST_TIME_ARGS (basesrc->priv->ts_offset));
+    } else {
+      basesrc->priv->ts_offset = 0;
+      GST_LOG_OBJECT (basesrc, "no timestamp offset needed");
+    }
+
+    if (!GST_CLOCK_TIME_IS_VALID (timestamp)) {
+      if (do_timestamp)
+        timestamp = running_time;
+      else
+        timestamp = 0;
+
+      GST_BUFFER_TIMESTAMP (buffer) = timestamp;
+
+      GST_LOG_OBJECT (basesrc, "created timestamp: %" GST_TIME_FORMAT,
+          GST_TIME_ARGS (timestamp));
+    }
+
+    /* add the timestamp offset we need for sync */
+    timestamp += basesrc->priv->ts_offset;
+  } else {
+    /* not the first buffer, the timestamp is the diff between the clock and
+     * base_time */
+    if (do_timestamp && !GST_CLOCK_TIME_IS_VALID (timestamp)) {
+      now = gst_clock_get_time (clock);
+
+      GST_BUFFER_TIMESTAMP (buffer) = now - base_time;
+
+      GST_LOG_OBJECT (basesrc, "created timestamp: %" GST_TIME_FORMAT,
+          GST_TIME_ARGS (now - base_time));
+    }
+  }
+
+  /* if we don't have a buffer timestamp, we don't sync */
+  if (!GST_CLOCK_TIME_IS_VALID (start))
+    goto no_sync;
+
+  if (basesrc->is_live && GST_CLOCK_TIME_IS_VALID (timestamp)) {
+    /* for pseudo live sources, add our ts_offset to the timestamp */
+    GST_BUFFER_TIMESTAMP (buffer) += basesrc->priv->ts_offset;
+    start += basesrc->priv->ts_offset;
+  }
+
+  GST_LOG_OBJECT (basesrc,
+      "waiting for clock, base time %" GST_TIME_FORMAT
+      ", stream_start %" GST_TIME_FORMAT,
+      GST_TIME_ARGS (base_time), GST_TIME_ARGS (start));
+  GST_OBJECT_UNLOCK (basesrc);
+
+  result = gst_base_src_wait (basesrc, clock, start + base_time);
+
+  GST_LOG_OBJECT (basesrc, "clock entry done: %d", result);
+
+  return result;
+
+  /* special cases */
+no_clock:
+  {
+    GST_DEBUG_OBJECT (basesrc, "we have no clock");
+    GST_OBJECT_UNLOCK (basesrc);
+    return GST_CLOCK_OK;
+  }
+no_sync:
+  {
+    GST_DEBUG_OBJECT (basesrc, "no sync needed");
+    GST_OBJECT_UNLOCK (basesrc);
+    return GST_CLOCK_OK;
+  }
+}
+
+static gboolean
+gst_base_src_update_length (GstBaseSrc * src, guint64 offset, guint * length)
+{
+  guint64 size, maxsize;
+  GstBaseSrcClass *bclass;
+
+  bclass = GST_BASE_SRC_GET_CLASS (src);
+
+  /* only operate if we are working with bytes */
+  if (src->segment.format != GST_FORMAT_BYTES)
+    return TRUE;
+
+  /* get total file size */
+  size = (guint64) src->segment.duration;
+
+  /* the max amount of bytes to read is the total size or
+   * up to the segment.stop if present. */
+  if (src->segment.stop != -1)
+    maxsize = MIN (size, src->segment.stop);
+  else
+    maxsize = size;
+
+  GST_DEBUG_OBJECT (src,
+      "reading offset %" G_GUINT64_FORMAT ", length %u, size %" G_GINT64_FORMAT
+      ", segment.stop %" G_GINT64_FORMAT ", maxsize %" G_GINT64_FORMAT, offset,
+      *length, size, src->segment.stop, maxsize);
+
+  /* check size if we have one */
+  if (maxsize != -1) {
+    /* if we run past the end, check if the file became bigger and 
+     * retry. */
+    if (G_UNLIKELY (offset + *length >= maxsize)) {
+      /* see if length of the file changed */
+      if (bclass->get_size)
+        if (!bclass->get_size (src, &size))
+          size = -1;
+
+      gst_segment_set_duration (&src->segment, GST_FORMAT_BYTES, size);
+
+      /* make sure we don't exceed the configured segment stop
+       * if it was set */
+      if (src->segment.stop != -1)
+        maxsize = MIN (size, src->segment.stop);
+      else
+        maxsize = size;
+
+      /* if we are at or past the end, EOS */
+      if (G_UNLIKELY (offset >= maxsize))
+        goto unexpected_length;
+
+      /* else we can clip to the end */
+      if (G_UNLIKELY (offset + *length >= maxsize))
+        *length = maxsize - offset;
+
+    }
+  }
+
+  /* keep track of current position. segment is in bytes, we checked 
+   * that above. */
+  gst_segment_set_last_stop (&src->segment, GST_FORMAT_BYTES, offset);
+
+  return TRUE;
+
+  /* ERRORS */
+unexpected_length:
+  {
+    return FALSE;
+  }
+}
+
+/* must be called with LIVE_LOCK */
+static GstFlowReturn
+gst_base_src_get_range (GstBaseSrc * src, guint64 offset, guint length,
+    GstBuffer ** buf)
+{
+  GstFlowReturn ret;
+  GstBaseSrcClass *bclass;
+  GstClockReturn status;
+
+  bclass = GST_BASE_SRC_GET_CLASS (src);
+
+  if (src->is_live) {
+    while (G_UNLIKELY (!src->live_running)) {
+      ret = gst_base_src_wait_playing (src);
+      if (ret != GST_FLOW_OK)
+        goto stopped;
+    }
+  }
+
+  if (G_UNLIKELY (!GST_OBJECT_FLAG_IS_SET (src, GST_BASE_SRC_STARTED)))
+    goto not_started;
+
+  if (G_UNLIKELY (!bclass->create))
+    goto no_function;
+
+  if (G_UNLIKELY (!gst_base_src_update_length (src, offset, &length)))
+    goto unexpected_length;
+
+  /* normally we don't count buffers */
+  if (G_UNLIKELY (src->num_buffers_left >= 0)) {
+    if (src->num_buffers_left == 0)
+      goto reached_num_buffers;
+    else
+      src->num_buffers_left--;
+  }
+
+  GST_DEBUG_OBJECT (src,
+      "calling create offset %" G_GUINT64_FORMAT " length %u, time %"
+      G_GINT64_FORMAT, offset, length, src->segment.time);
+
+  ret = bclass->create (src, offset, length, buf);
+  if (G_UNLIKELY (ret != GST_FLOW_OK))
+    goto not_ok;
+
+  /* no timestamp set and we are at offset 0, we can timestamp with 0 */
+  if (offset == 0 && src->segment.time == 0
+      && GST_BUFFER_TIMESTAMP (*buf) == -1)
+    GST_BUFFER_TIMESTAMP (*buf) = 0;
+
+  /* now sync before pushing the buffer */
+  status = gst_base_src_do_sync (src, *buf);
+
+  /* waiting for the clock could have made us flushing */
+  if (G_UNLIKELY (src->priv->flushing))
+    goto flushing;
+
+  if (G_UNLIKELY (src->priv->pending_eos))
+    goto eos;
+
+  switch (status) {
+    case GST_CLOCK_EARLY:
+      /* the buffer is too late. We currently don't drop the buffer. */
+      GST_DEBUG_OBJECT (src, "buffer too late!, returning anyway");
+      break;
+    case GST_CLOCK_OK:
+      /* buffer synchronised properly */
+      GST_DEBUG_OBJECT (src, "buffer ok");
+      break;
+    case GST_CLOCK_UNSCHEDULED:
+      /* this case is triggered when we were waiting for the clock and
+       * it got unlocked because we did a state change. We return 
+       * WRONG_STATE in this case to stop the dataflow also get rid of the
+       * produced buffer. */
+      GST_DEBUG_OBJECT (src,
+          "clock was unscheduled (%d), returning WRONG_STATE", status);
+      gst_buffer_unref (*buf);
+      *buf = NULL;
+      ret = GST_FLOW_WRONG_STATE;
+      break;
+    default:
+      /* all other result values are unexpected and errors */
+      GST_ELEMENT_ERROR (src, CORE, CLOCK,
+          (_("Internal clock error.")),
+          ("clock returned unexpected return value %d", status));
+      gst_buffer_unref (*buf);
+      *buf = NULL;
+      ret = GST_FLOW_ERROR;
+      break;
+  }
+  return ret;
+
+  /* ERROR */
+stopped:
+  {
+    GST_DEBUG_OBJECT (src, "wait_playing returned %d (%s)", ret,
+        gst_flow_get_name (ret));
+    return ret;
+  }
+not_ok:
+  {
+    GST_DEBUG_OBJECT (src, "create returned %d (%s)", ret,
+        gst_flow_get_name (ret));
+    return ret;
+  }
+not_started:
+  {
+    GST_DEBUG_OBJECT (src, "getrange but not started");
+    return GST_FLOW_WRONG_STATE;
+  }
+no_function:
+  {
+    GST_DEBUG_OBJECT (src, "no create function");
+    return GST_FLOW_ERROR;
+  }
+unexpected_length:
+  {
+    GST_DEBUG_OBJECT (src, "unexpected length %u (offset=%" G_GUINT64_FORMAT
+        ", size=%" G_GINT64_FORMAT ")", length, offset, src->segment.duration);
+    return GST_FLOW_UNEXPECTED;
+  }
+reached_num_buffers:
+  {
+    GST_DEBUG_OBJECT (src, "sent all buffers");
+    return GST_FLOW_UNEXPECTED;
+  }
+flushing:
+  {
+    GST_DEBUG_OBJECT (src, "we are flushing");
+    gst_buffer_unref (*buf);
+    *buf = NULL;
+    return GST_FLOW_WRONG_STATE;
+  }
+eos:
+  {
+    GST_DEBUG_OBJECT (src, "we are EOS");
+    gst_buffer_unref (*buf);
+    *buf = NULL;
+    return GST_FLOW_UNEXPECTED;
+  }
+}
+
+static GstFlowReturn
+gst_base_src_pad_get_range (GstPad * pad, guint64 offset, guint length,
+    GstBuffer ** buf)
+{
+  GstBaseSrc *src;
+  GstFlowReturn res;
+
+  src = GST_BASE_SRC (gst_pad_get_parent (pad));
+
+  GST_LIVE_LOCK (src);
+  if (G_UNLIKELY (src->priv->flushing))
+    goto flushing;
+
+  /* if we're EOS, return right away */
+  if (G_UNLIKELY (src->priv->pending_eos))
+    goto eos;
+
+  res = gst_base_src_get_range (src, offset, length, buf);
+
+done:
+  GST_LIVE_UNLOCK (src);
+
+  gst_object_unref (src);
+
+  return res;
+
+  /* ERRORS */
+flushing:
+  {
+    GST_DEBUG_OBJECT (src, "we are flushing");
+    res = GST_FLOW_WRONG_STATE;
+    goto done;
+  }
+eos:
+  {
+    GST_DEBUG_OBJECT (src, "we are EOS");
+    res = GST_FLOW_UNEXPECTED;
+    goto done;
+  }
+}
+
+static gboolean
+gst_base_src_default_check_get_range (GstBaseSrc * src)
+{
+  gboolean res;
+
+  if (!GST_OBJECT_FLAG_IS_SET (src, GST_BASE_SRC_STARTED)) {
+    GST_LOG_OBJECT (src, "doing start/stop to check get_range support");
+    if (G_LIKELY (gst_base_src_start (src)))
+      gst_base_src_stop (src);
+  }
+
+  /* we can operate in getrange mode if the native format is bytes
+   * and we are seekable, this condition is set in the random_access
+   * flag and is set in the _start() method. */
+  res = src->random_access;
+
+  return res;
+}
+
+static gboolean
+gst_base_src_check_get_range (GstBaseSrc * src)
+{
+  GstBaseSrcClass *bclass;
+  gboolean res;
+
+  bclass = GST_BASE_SRC_GET_CLASS (src);
+
+  if (bclass->check_get_range == NULL)
+    goto no_function;
+
+  res = bclass->check_get_range (src);
+  GST_LOG_OBJECT (src, "%s() returned %d",
+      GST_DEBUG_FUNCPTR_NAME (bclass->check_get_range), (gint) res);
+
+  return res;
+
+  /* ERRORS */
+no_function:
+  {
+    GST_WARNING_OBJECT (src, "no check_get_range function set");
+    return FALSE;
+  }
+}
+
+static gboolean
+gst_base_src_pad_check_get_range (GstPad * pad)
+{
+  GstBaseSrc *src;
+  gboolean res;
+
+  src = GST_BASE_SRC (GST_OBJECT_PARENT (pad));
+
+  res = gst_base_src_check_get_range (src);
+
+  return res;
+}
+
+static void
+gst_base_src_loop (GstPad * pad)
+{
+  GstBaseSrc *src;
+  GstBuffer *buf = NULL;
+  GstFlowReturn ret;
+  gint64 position;
+  gboolean eos;
+  gulong blocksize;
+
+  eos = FALSE;
+
+  src = GST_BASE_SRC (GST_OBJECT_PARENT (pad));
+
+  GST_LIVE_LOCK (src);
+  if (G_UNLIKELY (src->priv->flushing))
+    goto flushing;
+
+  /* if we're EOS, return right away */
+  if (G_UNLIKELY (src->priv->pending_eos))
+    goto eos;
+
+  src->priv->last_sent_eos = FALSE;
+
+  blocksize = src->blocksize;
+
+  /* if we operate in bytes, we can calculate an offset */
+  if (src->segment.format == GST_FORMAT_BYTES) {
+    position = src->segment.last_stop;
+    /* for negative rates, start with subtracting the blocksize */
+    if (src->segment.rate < 0.0) {
+      /* we cannot go below segment.start */
+      if (position > src->segment.start + blocksize)
+        position -= blocksize;
+      else {
+        /* last block, remainder up to segment.start */
+        blocksize = position - src->segment.start;
+        position = src->segment.start;
+      }
+    }
+  } else
+    position = -1;
+
+  ret = gst_base_src_get_range (src, position, blocksize, &buf);
+  if (G_UNLIKELY (ret != GST_FLOW_OK)) {
+    GST_INFO_OBJECT (src, "pausing after gst_base_src_get_range() = %s",
+        gst_flow_get_name (ret));
+    GST_LIVE_UNLOCK (src);
+    goto pause;
+  }
+  /* this should not happen */
+  if (G_UNLIKELY (buf == NULL))
+    goto null_buffer;
+
+  /* push events to close/start our segment before we push the buffer. */
+  if (G_UNLIKELY (src->priv->close_segment)) {
+    gst_pad_push_event (pad, src->priv->close_segment);
+    src->priv->close_segment = NULL;
+  }
+  if (G_UNLIKELY (src->priv->start_segment)) {
+    gst_pad_push_event (pad, src->priv->start_segment);
+    src->priv->start_segment = NULL;
+  }
+
+  /* figure out the new position */
+  switch (src->segment.format) {
+    case GST_FORMAT_BYTES:
+    {
+      guint bufsize = GST_BUFFER_SIZE (buf);
+
+      /* we subtracted above for negative rates */
+      if (src->segment.rate >= 0.0)
+        position += bufsize;
+      break;
+    }
+    case GST_FORMAT_TIME:
+    {
+      GstClockTime start, duration;
+
+      start = GST_BUFFER_TIMESTAMP (buf);
+      duration = GST_BUFFER_DURATION (buf);
+
+      if (GST_CLOCK_TIME_IS_VALID (start))
+        position = start;
+      else
+        position = src->segment.last_stop;
+
+      if (GST_CLOCK_TIME_IS_VALID (duration)) {
+        if (src->segment.rate >= 0.0)
+          position += duration;
+        else if (position > duration)
+          position -= duration;
+        else
+          position = 0;
+      }
+      break;
+    }
+    case GST_FORMAT_DEFAULT:
+      if (src->segment.rate >= 0.0)
+        position = GST_BUFFER_OFFSET_END (buf);
+      else
+        position = GST_BUFFER_OFFSET (buf);
+      break;
+    default:
+      position = -1;
+      break;
+  }
+  if (position != -1) {
+    if (src->segment.rate >= 0.0) {
+      /* positive rate, check if we reached the stop */
+      if (src->segment.stop != -1) {
+        if (position >= src->segment.stop) {
+          eos = TRUE;
+          position = src->segment.stop;
+        }
+      }
+    } else {
+      /* negative rate, check if we reached the start. start is always set to
+       * something different from -1 */
+      if (position <= src->segment.start) {
+        eos = TRUE;
+        position = src->segment.start;
+      }
+      /* when going reverse, all buffers are DISCONT */
+      src->priv->discont = TRUE;
+    }
+    gst_segment_set_last_stop (&src->segment, src->segment.format, position);
+  }
+
+  if (G_UNLIKELY (src->priv->discont)) {
+    buf = gst_buffer_make_metadata_writable (buf);
+    GST_BUFFER_FLAG_SET (buf, GST_BUFFER_FLAG_DISCONT);
+    src->priv->discont = FALSE;
+  }
+  GST_LIVE_UNLOCK (src);
+
+  ret = gst_pad_push (pad, buf);
+  if (G_UNLIKELY (ret != GST_FLOW_OK)) {
+    GST_INFO_OBJECT (src, "pausing after gst_pad_push() = %s",
+        gst_flow_get_name (ret));
+    goto pause;
+  }
+
+  if (G_UNLIKELY (eos)) {
+    GST_INFO_OBJECT (src, "pausing after end of segment");
+    ret = GST_FLOW_UNEXPECTED;
+    goto pause;
+  }
+
+done:
+  return;
+
+  /* special cases */
+flushing:
+  {
+    GST_DEBUG_OBJECT (src, "we are flushing");
+    GST_LIVE_UNLOCK (src);
+    ret = GST_FLOW_WRONG_STATE;
+    goto pause;
+  }
+eos:
+  {
+    GST_DEBUG_OBJECT (src, "we are EOS");
+    GST_LIVE_UNLOCK (src);
+    ret = GST_FLOW_UNEXPECTED;
+    goto pause;
+  }
+pause:
+  {
+    const gchar *reason = gst_flow_get_name (ret);
+
+    GST_DEBUG_OBJECT (src, "pausing task, reason %s", reason);
+    src->data.ABI.running = FALSE;
+    gst_pad_pause_task (pad);
+    if (GST_FLOW_IS_FATAL (ret) || ret == GST_FLOW_NOT_LINKED) {
+      if (ret == GST_FLOW_UNEXPECTED) {
+        /* perform EOS logic */
+        if (src->segment.flags & GST_SEEK_FLAG_SEGMENT) {
+          gst_element_post_message (GST_ELEMENT_CAST (src),
+              gst_message_new_segment_done (GST_OBJECT_CAST (src),
+                  src->segment.format, src->segment.last_stop));
+        } else {
+          gst_pad_push_event (pad, gst_event_new_eos ());
+          src->priv->last_sent_eos = TRUE;
+        }
+      } else {
+        /* for fatal errors we post an error message, post the error
+         * first so the app knows about the error first. */
+        GST_ELEMENT_ERROR (src, STREAM, FAILED,
+            (_("Internal data flow error.")),
+            ("streaming task paused, reason %s (%d)", reason, ret));
+        gst_pad_push_event (pad, gst_event_new_eos ());
+        src->priv->last_sent_eos = TRUE;
+      }
+    }
+    goto done;
+  }
+null_buffer:
+  {
+    GST_ELEMENT_ERROR (src, STREAM, FAILED,
+        (_("Internal data flow error.")), ("element returned NULL buffer"));
+    GST_LIVE_UNLOCK (src);
+    /* we finished the segment on error */
+    ret = GST_FLOW_ERROR;
+    goto done;
+  }
+}
+
+/* default negotiation code. 
+ *
+ * Take intersection between src and sink pads, take first
+ * caps and fixate. 
+ */
+static gboolean
+gst_base_src_default_negotiate (GstBaseSrc * basesrc)
+{
+  GstCaps *thiscaps;
+  GstCaps *caps = NULL;
+  GstCaps *peercaps = NULL;
+  gboolean result = FALSE;
+
+  /* first see what is possible on our source pad */
+  thiscaps = gst_pad_get_caps (GST_BASE_SRC_PAD (basesrc));
+  GST_DEBUG_OBJECT (basesrc, "caps of src: %" GST_PTR_FORMAT, thiscaps);
+  /* nothing or anything is allowed, we're done */
+  if (thiscaps == NULL || gst_caps_is_any (thiscaps))
+    goto no_nego_needed;
+
+  /* get the peer caps */
+  peercaps = gst_pad_peer_get_caps (GST_BASE_SRC_PAD (basesrc));
+  GST_DEBUG_OBJECT (basesrc, "caps of peer: %" GST_PTR_FORMAT, peercaps);
+  if (peercaps) {
+    GstCaps *icaps;
+
+    /* get intersection */
+    icaps = gst_caps_intersect (thiscaps, peercaps);
+    GST_DEBUG_OBJECT (basesrc, "intersect: %" GST_PTR_FORMAT, icaps);
+    gst_caps_unref (thiscaps);
+    gst_caps_unref (peercaps);
+    if (icaps) {
+      /* take first (and best, since they are sorted) possibility */
+      caps = gst_caps_copy_nth (icaps, 0);
+      gst_caps_unref (icaps);
+    }
+  } else {
+    /* no peer, work with our own caps then */
+    caps = thiscaps;
+  }
+  if (caps) {
+    caps = gst_caps_make_writable (caps);
+    gst_caps_truncate (caps);
+
+    /* now fixate */
+    if (!gst_caps_is_empty (caps)) {
+      gst_pad_fixate_caps (GST_BASE_SRC_PAD (basesrc), caps);
+      GST_DEBUG_OBJECT (basesrc, "fixated to: %" GST_PTR_FORMAT, caps);
+
+      if (gst_caps_is_any (caps)) {
+        /* hmm, still anything, so element can do anything and
+         * nego is not needed */
+        result = TRUE;
+      } else if (gst_caps_is_fixed (caps)) {
+        /* yay, fixed caps, use those then */
+        gst_pad_set_caps (GST_BASE_SRC_PAD (basesrc), caps);
+        result = TRUE;
+      }
+    }
+    gst_caps_unref (caps);
+  }
+  return result;
+
+no_nego_needed:
+  {
+    GST_DEBUG_OBJECT (basesrc, "no negotiation needed");
+    if (thiscaps)
+      gst_caps_unref (thiscaps);
+    return TRUE;
+  }
+}
+
+static gboolean
+gst_base_src_negotiate (GstBaseSrc * basesrc)
+{
+  GstBaseSrcClass *bclass;
+  gboolean result = TRUE;
+
+  bclass = GST_BASE_SRC_GET_CLASS (basesrc);
+
+  if (bclass->negotiate)
+    result = bclass->negotiate (basesrc);
+
+  return result;
+}
+
+static gboolean
+gst_base_src_start (GstBaseSrc * basesrc)
+{
+  GstBaseSrcClass *bclass;
+  gboolean result;
+  guint64 size;
+
+  if (GST_OBJECT_FLAG_IS_SET (basesrc, GST_BASE_SRC_STARTED))
+    return TRUE;
+
+  GST_DEBUG_OBJECT (basesrc, "starting source");
+
+  basesrc->num_buffers_left = basesrc->num_buffers;
+
+  gst_segment_init (&basesrc->segment, basesrc->segment.format);
+  basesrc->data.ABI.running = FALSE;
+
+  bclass = GST_BASE_SRC_GET_CLASS (basesrc);
+  if (bclass->start)
+    result = bclass->start (basesrc);
+  else
+    result = TRUE;
+
+  if (!result)
+    goto could_not_start;
+
+  GST_OBJECT_FLAG_SET (basesrc, GST_BASE_SRC_STARTED);
+
+  /* figure out the size */
+  if (basesrc->segment.format == GST_FORMAT_BYTES) {
+    if (bclass->get_size) {
+      if (!(result = bclass->get_size (basesrc, &size)))
+        size = -1;
+    } else {
+      result = FALSE;
+      size = -1;
+    }
+    GST_DEBUG_OBJECT (basesrc, "setting size %" G_GUINT64_FORMAT, size);
+    /* only update the size when operating in bytes, subclass is supposed
+     * to set duration in the start method for other formats */
+    gst_segment_set_duration (&basesrc->segment, GST_FORMAT_BYTES, size);
+  } else {
+    size = -1;
+  }
+
+  GST_DEBUG_OBJECT (basesrc,
+      "format: %d, have size: %d, size: %" G_GUINT64_FORMAT ", duration: %"
+      G_GINT64_FORMAT, basesrc->segment.format, result, size,
+      basesrc->segment.duration);
+
+  /* check if we can seek */
+  if (bclass->is_seekable)
+    basesrc->seekable = bclass->is_seekable (basesrc);
+  else
+    basesrc->seekable = FALSE;
+
+  GST_DEBUG_OBJECT (basesrc, "is seekable: %d", basesrc->seekable);
+
+  /* update for random access flag */
+  basesrc->random_access = basesrc->seekable &&
+      basesrc->segment.format == GST_FORMAT_BYTES;
+
+  GST_DEBUG_OBJECT (basesrc, "is random_access: %d", basesrc->random_access);
+
+  /* run typefind if we are random_access and the typefinding is enabled. */
+  if (basesrc->random_access && basesrc->data.ABI.typefind && size != -1) {
+    GstCaps *caps;
+
+    caps = gst_type_find_helper (basesrc->srcpad, size);
+    gst_pad_set_caps (basesrc->srcpad, caps);
+    gst_caps_unref (caps);
+  } else {
+    /* use class or default negotiate function */
+    if (!gst_base_src_negotiate (basesrc))
+      goto could_not_negotiate;
+  }
+
+  return TRUE;
+
+  /* ERROR */
+could_not_start:
+  {
+    GST_DEBUG_OBJECT (basesrc, "could not start");
+    /* subclass is supposed to post a message. We don't have to call _stop. */
+    return FALSE;
+  }
+could_not_negotiate:
+  {
+    GST_DEBUG_OBJECT (basesrc, "could not negotiate, stopping");
+    GST_ELEMENT_ERROR (basesrc, STREAM, FORMAT,
+        ("Could not negotiate format"), ("Check your filtered caps, if any"));
+    /* we must call stop */
+    gst_base_src_stop (basesrc);
+    return FALSE;
+  }
+}
+
+static gboolean
+gst_base_src_stop (GstBaseSrc * basesrc)
+{
+  GstBaseSrcClass *bclass;
+  gboolean result = TRUE;
+
+  if (!GST_OBJECT_FLAG_IS_SET (basesrc, GST_BASE_SRC_STARTED))
+    return TRUE;
+
+  GST_DEBUG_OBJECT (basesrc, "stopping source");
+
+  bclass = GST_BASE_SRC_GET_CLASS (basesrc);
+  if (bclass->stop)
+    result = bclass->stop (basesrc);
+
+  if (result)
+    GST_OBJECT_FLAG_UNSET (basesrc, GST_BASE_SRC_STARTED);
+
+  return result;
+}
+
+/* start or stop flushing dataprocessing 
+ */
+static gboolean
+gst_base_src_set_flushing (GstBaseSrc * basesrc,
+    gboolean flushing, gboolean live_play, gboolean unlock, gboolean * playing)
+{
+  GstBaseSrcClass *bclass;
+
+  bclass = GST_BASE_SRC_GET_CLASS (basesrc);
+
+  if (flushing && unlock) {
+    /* unlock any subclasses, we need to do this before grabbing the
+     * LIVE_LOCK since we hold this lock before going into ::create. We pass an
+     * unlock to the params because of backwards compat (see seek handler)*/
+    if (bclass->unlock)
+      bclass->unlock (basesrc);
+  }
+
+  /* the live lock is released when we are blocked, waiting for playing or
+   * when we sync to the clock. */
+  GST_LIVE_LOCK (basesrc);
+  if (playing)
+    *playing = basesrc->live_running;
+  basesrc->priv->flushing = flushing;
+  if (flushing) {
+    /* if we are locked in the live lock, signal it to make it flush */
+    basesrc->live_running = TRUE;
+    /* clear pending EOS if any */
+    basesrc->priv->pending_eos = FALSE;
+
+    /* step 1, now that we have the LIVE lock, clear our unlock request */
+    if (bclass->unlock_stop)
+      bclass->unlock_stop (basesrc);
+
+    /* step 2, unblock clock sync (if any) or any other blocking thing */
+    if (basesrc->clock_id)
+      gst_clock_id_unschedule (basesrc->clock_id);
+  } else {
+    /* signal the live source that it can start playing */
+    basesrc->live_running = live_play;
+  }
+  GST_LIVE_SIGNAL (basesrc);
+  GST_LIVE_UNLOCK (basesrc);
+
+  return TRUE;
+}
+
+/* the purpose of this function is to make sure that a live source blocks in the
+ * LIVE lock or leaves the LIVE lock and continues playing. */
+static gboolean
+gst_base_src_set_playing (GstBaseSrc * basesrc, gboolean live_play)
+{
+  GstBaseSrcClass *bclass;
+
+  bclass = GST_BASE_SRC_GET_CLASS (basesrc);
+
+  /* unlock subclasses locked in ::create, we only do this when we stop playing. */
+  if (!live_play) {
+    GST_DEBUG_OBJECT (basesrc, "unlock");
+    if (bclass->unlock)
+      bclass->unlock (basesrc);
+  }
+
+  /* we are now able to grab the LIVE lock, when we get it, we can be
+   * waiting for PLAYING while blocked in the LIVE cond or we can be waiting
+   * for the clock. */
+  GST_LIVE_LOCK (basesrc);
+  GST_DEBUG_OBJECT (basesrc, "unschedule clock");
+
+  /* unblock clock sync (if any) */
+  if (basesrc->clock_id)
+    gst_clock_id_unschedule (basesrc->clock_id);
+
+  /* configure what to do when we get to the LIVE lock. */
+  GST_DEBUG_OBJECT (basesrc, "live running %d", live_play);
+  basesrc->live_running = live_play;
+
+  if (live_play) {
+    gboolean start;
+
+    /* clear our unlock request when going to PLAYING */
+    GST_DEBUG_OBJECT (basesrc, "unlock stop");
+    if (bclass->unlock_stop)
+      bclass->unlock_stop (basesrc);
+
+    /* for live sources we restart the timestamp correction */
+    basesrc->priv->latency = -1;
+    /* have to restart the task in case it stopped because of the unlock when
+     * we went to PAUSED. Only do this if we operating in push mode. */
+    GST_OBJECT_LOCK (basesrc->srcpad);
+    start = (GST_PAD_ACTIVATE_MODE (basesrc->srcpad) == GST_ACTIVATE_PUSH);
+    GST_OBJECT_UNLOCK (basesrc->srcpad);
+    if (start)
+      gst_pad_start_task (basesrc->srcpad, (GstTaskFunction) gst_base_src_loop,
+          basesrc->srcpad);
+    GST_DEBUG_OBJECT (basesrc, "signal");
+    GST_LIVE_SIGNAL (basesrc);
+  }
+  GST_LIVE_UNLOCK (basesrc);
+
+  return TRUE;
+}
+
+static gboolean
+gst_base_src_activate_push (GstPad * pad, gboolean active)
+{
+  GstBaseSrc *basesrc;
+  GstEvent *event;
+
+  basesrc = GST_BASE_SRC (GST_OBJECT_PARENT (pad));
+
+  /* prepare subclass first */
+  if (active) {
+    GST_DEBUG_OBJECT (basesrc, "Activating in push mode");
+
+    if (G_UNLIKELY (!basesrc->can_activate_push))
+      goto no_push_activation;
+
+    if (G_UNLIKELY (!gst_base_src_start (basesrc)))
+      goto error_start;
+
+    basesrc->priv->last_sent_eos = FALSE;
+    basesrc->priv->discont = TRUE;
+    gst_base_src_set_flushing (basesrc, FALSE, FALSE, FALSE, NULL);
+
+    /* do initial seek, which will start the task */
+    GST_OBJECT_LOCK (basesrc);
+    event = basesrc->data.ABI.pending_seek;
+    basesrc->data.ABI.pending_seek = NULL;
+    GST_OBJECT_UNLOCK (basesrc);
+
+    /* no need to unlock anything, the task is certainly
+     * not running here. The perform seek code will start the task when
+     * finished. */
+    if (G_UNLIKELY (!gst_base_src_perform_seek (basesrc, event, FALSE)))
+      goto seek_failed;
+
+    if (event)
+      gst_event_unref (event);
+  } else {
+    GST_DEBUG_OBJECT (basesrc, "Deactivating in push mode");
+    /* flush all */
+    gst_base_src_set_flushing (basesrc, TRUE, FALSE, TRUE, NULL);
+    /* stop the task */
+    gst_pad_stop_task (pad);
+    /* now we can stop the source */
+    if (G_UNLIKELY (!gst_base_src_stop (basesrc)))
+      goto error_stop;
+  }
+  return TRUE;
+
+  /* ERRORS */
+no_push_activation:
+  {
+    GST_WARNING_OBJECT (basesrc, "Subclass disabled push-mode activation");
+    return FALSE;
+  }
+error_start:
+  {
+    GST_WARNING_OBJECT (basesrc, "Failed to start in push mode");
+    return FALSE;
+  }
+seek_failed:
+  {
+    GST_ERROR_OBJECT (basesrc, "Failed to perform initial seek");
+    gst_base_src_stop (basesrc);
+    if (event)
+      gst_event_unref (event);
+    return FALSE;
+  }
+error_stop:
+  {
+    GST_DEBUG_OBJECT (basesrc, "Failed to stop in push mode");
+    return FALSE;
+  }
+}
+
+static gboolean
+gst_base_src_activate_pull (GstPad * pad, gboolean active)
+{
+  GstBaseSrc *basesrc;
+
+  basesrc = GST_BASE_SRC (GST_OBJECT_PARENT (pad));
+
+  /* prepare subclass first */
+  if (active) {
+    GST_DEBUG_OBJECT (basesrc, "Activating in pull mode");
+    if (G_UNLIKELY (!gst_base_src_start (basesrc)))
+      goto error_start;
+
+    /* if not random_access, we cannot operate in pull mode for now */
+    if (G_UNLIKELY (!gst_base_src_check_get_range (basesrc)))
+      goto no_get_range;
+
+    /* stop flushing now but for live sources, still block in the LIVE lock when
+     * we are not yet PLAYING */
+    gst_base_src_set_flushing (basesrc, FALSE, FALSE, FALSE, NULL);
+  } else {
+    GST_DEBUG_OBJECT (basesrc, "Deactivating in pull mode");
+    /* flush all, there is no task to stop */
+    gst_base_src_set_flushing (basesrc, TRUE, FALSE, TRUE, NULL);
+
+    /* don't send EOS when going from PAUSED => READY when in pull mode */
+    basesrc->priv->last_sent_eos = TRUE;
+
+    if (G_UNLIKELY (!gst_base_src_stop (basesrc)))
+      goto error_stop;
+  }
+  return TRUE;
+
+  /* ERRORS */
+error_start:
+  {
+    GST_ERROR_OBJECT (basesrc, "Failed to start in pull mode");
+    return FALSE;
+  }
+no_get_range:
+  {
+    GST_ERROR_OBJECT (basesrc, "Cannot operate in pull mode, stopping");
+    gst_base_src_stop (basesrc);
+    return FALSE;
+  }
+error_stop:
+  {
+    GST_ERROR_OBJECT (basesrc, "Failed to stop in pull mode");
+    return FALSE;
+  }
+}
+
+static GstStateChangeReturn
+gst_base_src_change_state (GstElement * element, GstStateChange transition)
+{
+  GstBaseSrc *basesrc;
+  GstStateChangeReturn result;
+  gboolean no_preroll = FALSE;
+
+  basesrc = GST_BASE_SRC (element);
+
+  switch (transition) {
+    case GST_STATE_CHANGE_NULL_TO_READY:
+      break;
+    case GST_STATE_CHANGE_READY_TO_PAUSED:
+      no_preroll = gst_base_src_is_live (basesrc);
+      break;
+    case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
+      GST_DEBUG_OBJECT (basesrc, "PAUSED->PLAYING");
+      if (gst_base_src_is_live (basesrc)) {
+        /* now we can start playback */
+        gst_base_src_set_playing (basesrc, TRUE);
+      }
+      break;
+    default:
+      break;
+  }
+
+  if ((result =
+          GST_ELEMENT_CLASS (parent_class)->change_state (element,
+              transition)) == GST_STATE_CHANGE_FAILURE)
+    goto failure;
+
+  switch (transition) {
+    case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
+      GST_DEBUG_OBJECT (basesrc, "PLAYING->PAUSED");
+      if (gst_base_src_is_live (basesrc)) {
+        /* make sure we block in the live lock in PAUSED */
+        gst_base_src_set_playing (basesrc, FALSE);
+        no_preroll = TRUE;
+      }
+      break;
+    case GST_STATE_CHANGE_PAUSED_TO_READY:
+    {
+      GstEvent **event_p;
+
+      /* we don't need to unblock anything here, the pad deactivation code
+       * already did this */
+
+      /* FIXME, deprecate this behaviour, it is very dangerous.
+       * the prefered way of sending EOS downstream is by sending
+       * the EOS event to the element */
+      if (!basesrc->priv->last_sent_eos) {
+        GST_DEBUG_OBJECT (basesrc, "Sending EOS event");
+        gst_pad_push_event (basesrc->srcpad, gst_event_new_eos ());
+        basesrc->priv->last_sent_eos = TRUE;
+      }
+      basesrc->priv->pending_eos = FALSE;
+      event_p = &basesrc->data.ABI.pending_seek;
+      gst_event_replace (event_p, NULL);
+      event_p = &basesrc->priv->close_segment;
+      gst_event_replace (event_p, NULL);
+      event_p = &basesrc->priv->start_segment;
+      gst_event_replace (event_p, NULL);
+      break;
+    }
+    case GST_STATE_CHANGE_READY_TO_NULL:
+      break;
+    default:
+      break;
+  }
+
+  if (no_preroll && result == GST_STATE_CHANGE_SUCCESS)
+    result = GST_STATE_CHANGE_NO_PREROLL;
+
+  return result;
+
+  /* ERRORS */
+failure:
+  {
+    GST_DEBUG_OBJECT (basesrc, "parent failed state change");
+    return result;
+  }
+}