/* GStreamer

 * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>

 *                    2000 Wim Taymans <wim.taymans@chello.be>

 *                    2005 Wim Taymans <wim@fluendo.com>

 *

 * gstevent.c: GstEvent subsystem

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Library General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Library General Public License for more details.

 *

 * You should have received a copy of the GNU Library General Public

 * License along with this library; if not, write to the

 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,

 * Boston, MA 02110-1301, USA.

 */

/**

 * SECTION:gstevent

 * @title: GstEvent

 * @short_description: Structure describing events that are passed up and down

 *                     a pipeline

 * @see_also: #GstPad, #GstElement

 *

 * The event class provides factory methods to construct events for sending

 * and functions to query (parse) received events.

 *

 * Events are usually created with gst_event_new_*() which takes event-type

 * specific parameters as arguments.

 * To send an event application will usually use gst_element_send_event() and

 * elements will use gst_pad_send_event() or gst_pad_push_event().

 * The event should be unreffed with gst_event_unref() if it has not been sent.

 *

 * Events that have been received can be parsed with their respective

 * gst_event_parse_*() functions. It is valid to pass %NULL for unwanted details.

 *

 * Events are passed between elements in parallel to the data stream. Some events

 * are serialized with buffers, others are not. Some events only travel downstream,

 * others only upstream. Some events can travel both upstream and downstream.

 *

 * The events are used to signal special conditions in the datastream such as

 * EOS (end of stream) or the start of a new stream-segment.

 * Events are also used to flush the pipeline of any pending data.

 *

 * Most of the event API is used inside plugins. Applications usually only

 * construct and use seek events.

 * To do that gst_event_new_seek() is used to create a seek event. It takes

 * the needed parameters to specify seeking time and mode.

 * |[

 *   GstEvent *event;

 *   gboolean result;

 *   ...

 *   // construct a seek event to play the media from second 2 to 5, flush

 *   // the pipeline to decrease latency.

 *   event = gst_event_new_seek (1.0,

 *      GST_FORMAT_TIME,

 *      GST_SEEK_FLAG_FLUSH,

 *      GST_SEEK_TYPE_SET, 2 * GST_SECOND,

 *      GST_SEEK_TYPE_SET, 5 * GST_SECOND);

 *   ...

 *   result = gst_element_send_event (pipeline, event);

 *   if (!result)

 *     g_warning ("seek failed");

 *   ...

 * ]|

 */

#include "gst_private.h"

#include <string.h>             /* memcpy */

#include "gstinfo.h"

#include "gstevent.h"

#include "gstenumtypes.h"

#include "gstutils.h"

#include "gstquark.h"

#include "gstvalue.h"

GType _gst_event_type = 0;

typedef struct

{

  GstEvent event;

  GstStructure *structure;

  gint64 running_time_offset;

} GstEventImpl;

#define GST_EVENT_STRUCTURE(e)  (((GstEventImpl *)(e))->structure)

typedef struct

{

  const gint type;

  const gchar *name;

  GQuark quark;

} GstEventQuarks;

static GstEventQuarks event_quarks[] = {

  {GST_EVENT_UNKNOWN, "unknown", 0},

  {GST_EVENT_FLUSH_START, "flush-start", 0},

  {GST_EVENT_FLUSH_STOP, "flush-stop", 0},

  {GST_EVENT_SELECT_STREAMS, "select-streams", 0},

  {GST_EVENT_STREAM_START, "stream-start", 0},

  {GST_EVENT_STREAM_COLLECTION, "stream-collection", 0},

  {GST_EVENT_CAPS, "caps", 0},

  {GST_EVENT_SEGMENT, "segment", 0},

  {GST_EVENT_TAG, "tag", 0},

  {GST_EVENT_TOC, "toc", 0},

  {GST_EVENT_PROTECTION, "protection", 0},

  {GST_EVENT_BUFFERSIZE, "buffersize", 0},

  {GST_EVENT_SINK_MESSAGE, "sink-message", 0},

  {GST_EVENT_EOS, "eos", 0},

  {GST_EVENT_SEGMENT_DONE, "segment-done", 0},

  {GST_EVENT_GAP, "gap", 0},

  {GST_EVENT_QOS, "qos", 0},

  {GST_EVENT_SEEK, "seek", 0},

  {GST_EVENT_NAVIGATION, "navigation", 0},

  {GST_EVENT_LATENCY, "latency", 0},

  {GST_EVENT_STEP, "step", 0},

  {GST_EVENT_RECONFIGURE, "reconfigure", 0},

  {GST_EVENT_TOC_SELECT, "toc-select", 0},

  {GST_EVENT_CUSTOM_UPSTREAM, "custom-upstream", 0},

  {GST_EVENT_CUSTOM_DOWNSTREAM, "custom-downstream", 0},

  {GST_EVENT_CUSTOM_DOWNSTREAM_OOB, "custom-downstream-oob", 0},

  {GST_EVENT_CUSTOM_DOWNSTREAM_STICKY, "custom-downstream-sticky", 0},

  {GST_EVENT_CUSTOM_BOTH, "custom-both", 0},

  {GST_EVENT_CUSTOM_BOTH_OOB, "custom-both-oob", 0},

  {GST_EVENT_STREAM_GROUP_DONE, "stream-group-done", 0},

  {0, NULL, 0}

};

GST_DEFINE_MINI_OBJECT_TYPE (GstEvent, gst_event);

void

_priv_gst_event_initialize (void)

{

  gint i;

  _gst_event_type = gst_event_get_type ();

  g_type_class_ref (gst_seek_flags_get_type ());

  g_type_class_ref (gst_seek_type_get_type ());

  for (i = 0; event_quarks[i].name; i++) {

    event_quarks[i].quark = g_quark_from_static_string (event_quarks[i].name);

  }

}

/**

 * gst_event_type_get_name:

 * @type: the event type

 *

 * Get a printable name for the given event type. Do not modify or free.

 *

 * Returns: a reference to the static name of the event.

 */

const gchar *

gst_event_type_get_name (GstEventType type)

{

  gint i;

  for (i = 0; event_quarks[i].name; i++) {

    if (type == event_quarks[i].type)

      return event_quarks[i].name;

  }

  return "unknown";

}

/**

 * gst_event_type_to_quark:

 * @type: the event type

 *

 * Get the unique quark for the given event type.

 *

 * Returns: the quark associated with the event type

 */

GQuark

gst_event_type_to_quark (GstEventType type)

{

  gint i;

  for (i = 0; event_quarks[i].name; i++) {

    if (type == event_quarks[i].type)

      return event_quarks[i].quark;

  }

  return 0;

}

/**

 * gst_event_type_get_flags:

 * @type: a #GstEventType

 *

 * Gets the #GstEventTypeFlags associated with @type.

 *

 * Returns: a #GstEventTypeFlags.

 */

GstEventTypeFlags

gst_event_type_get_flags (GstEventType type)

{

  GstEventTypeFlags ret;

  ret = type & ((1 << GST_EVENT_NUM_SHIFT) - 1);

  return ret;

}

static void

_gst_event_free (GstEvent * event)

{

  GstStructure *s;

  g_return_if_fail (event != NULL);

  g_return_if_fail (GST_IS_EVENT (event));

  GST_CAT_LOG (GST_CAT_EVENT, "freeing event %p type %s", event,

      GST_EVENT_TYPE_NAME (event));

  s = GST_EVENT_STRUCTURE (event);

  if (s) {

    gst_structure_set_parent_refcount (s, NULL);

    gst_structure_free (s);

  }

  g_slice_free1 (sizeof (GstEventImpl), event);

}

static void gst_event_init (GstEventImpl * event, GstEventType type);

static GstEvent *

_gst_event_copy (GstEvent * event)

{

  GstEventImpl *copy;

  GstStructure *s;

  copy = g_slice_new0 (GstEventImpl);

  gst_event_init (copy, GST_EVENT_TYPE (event));

  GST_EVENT_TIMESTAMP (copy) = GST_EVENT_TIMESTAMP (event);

  GST_EVENT_SEQNUM (copy) = GST_EVENT_SEQNUM (event);

  s = GST_EVENT_STRUCTURE (event);

  if (s) {

    GST_EVENT_STRUCTURE (copy) = gst_structure_copy (s);

    gst_structure_set_parent_refcount (GST_EVENT_STRUCTURE (copy),

        &copy->event.mini_object.refcount);

  } else {

    GST_EVENT_STRUCTURE (copy) = NULL;

  }

  ((GstEventImpl *) copy)->running_time_offset =

      ((GstEventImpl *) event)->running_time_offset;

  return GST_EVENT_CAST (copy);

}

static void

gst_event_init (GstEventImpl * event, GstEventType type)

{

  gst_mini_object_init (GST_MINI_OBJECT_CAST (event), 0, _gst_event_type,

      (GstMiniObjectCopyFunction) _gst_event_copy, NULL,

      (GstMiniObjectFreeFunction) _gst_event_free);

  GST_EVENT_TYPE (event) = type;

  GST_EVENT_TIMESTAMP (event) = GST_CLOCK_TIME_NONE;

  GST_EVENT_SEQNUM (event) = gst_util_seqnum_next ();

  event->running_time_offset = 0;

}

/**

 * gst_event_new_custom:

 * @type: The type of the new event

 * @structure: (transfer full): the structure for the event. The event will

 *     take ownership of the structure.

 *

 * Create a new custom-typed event. This can be used for anything not

 * handled by other event-specific functions to pass an event to another

 * element.

 *

 * Make sure to allocate an event type with the #GST_EVENT_MAKE_TYPE macro,

 * assigning a free number and filling in the correct direction and

 * serialization flags.

 *

 * New custom events can also be created by subclassing the event type if

 * needed.

 *

 * Returns: (transfer full) (nullable): the new custom event.

 */

GstEvent *

gst_event_new_custom (GstEventType type, GstStructure * structure)

{

  GstEventImpl *event;

  event = g_slice_new0 (GstEventImpl);

  GST_CAT_DEBUG (GST_CAT_EVENT, "creating new event %p %s %d", event,

      gst_event_type_get_name (type), type);

  if (structure) {

    /* structure must not have a parent */

    if (!gst_structure_set_parent_refcount (structure,

            &event->event.mini_object.refcount))

      goto had_parent;

  }

  gst_event_init (event, type);

  GST_EVENT_STRUCTURE (event) = structure;

  return GST_EVENT_CAST (event);

  /* ERRORS */

had_parent:

  {

    g_slice_free1 (sizeof (GstEventImpl), event);

    g_warning ("structure is already owned by another object");

    return NULL;

  }

}

/**

 * gst_event_get_structure:

 * @event: The #GstEvent.

 *

 * Access the structure of the event.

 *

 * Returns: (transfer none) (nullable): The structure of the event. The

 * structure is still owned by the event, which means that you should not free

 * it and that the pointer becomes invalid when you free the event.

 *

 * MT safe.

 */

const GstStructure *

gst_event_get_structure (GstEvent * event)

{

  g_return_val_if_fail (GST_IS_EVENT (event), NULL);

  return GST_EVENT_STRUCTURE (event);

}

/**

 * gst_event_writable_structure:

 * @event: The #GstEvent.

 *

 * Get a writable version of the structure.

 *

 * Returns: (transfer none): The structure of the event. The structure

 * is still owned by the event, which means that you should not free

 * it and that the pointer becomes invalid when you free the event.

 * This function checks if @event is writable and will never return

 * %NULL.

 *

 * MT safe.

 */

GstStructure *

gst_event_writable_structure (GstEvent * event)

{

  GstStructure *structure;

  g_return_val_if_fail (GST_IS_EVENT (event), NULL);

  g_return_val_if_fail (gst_event_is_writable (event), NULL);

  structure = GST_EVENT_STRUCTURE (event);

  if (structure == NULL) {

    structure =

        gst_structure_new_id_empty (gst_event_type_to_quark (GST_EVENT_TYPE

            (event)));

    gst_structure_set_parent_refcount (structure, &event->mini_object.refcount);

    GST_EVENT_STRUCTURE (event) = structure;

  }

  return structure;

}

/**

 * gst_event_has_name:

 * @event: The #GstEvent.

 * @name: name to check

 *

 * Checks if @event has the given @name. This function is usually used to

 * check the name of a custom event.

 *

 * Returns: %TRUE if @name matches the name of the event structure.

 */

gboolean

gst_event_has_name (GstEvent * event, const gchar * name)

{

  g_return_val_if_fail (GST_IS_EVENT (event), FALSE);

  if (GST_EVENT_STRUCTURE (event) == NULL)

    return FALSE;

  return gst_structure_has_name (GST_EVENT_STRUCTURE (event), name);

}

/**

 * gst_event_get_seqnum:

 * @event: A #GstEvent.

 *

 * Retrieve the sequence number of a event.

 *

 * Events have ever-incrementing sequence numbers, which may also be set

 * explicitly via gst_event_set_seqnum(). Sequence numbers are typically used to

 * indicate that a event corresponds to some other set of events or messages,

 * for example an EOS event corresponding to a SEEK event. It is considered good

 * practice to make this correspondence when possible, though it is not

 * required.

 *

 * Note that events and messages share the same sequence number incrementor;

 * two events or messages will never have the same sequence number unless

 * that correspondence was made explicitly.

 *

 * Returns: The event's sequence number.

 *

 * MT safe.

 */

guint32

gst_event_get_seqnum (GstEvent * event)

{

  g_return_val_if_fail (GST_IS_EVENT (event), -1);

  return GST_EVENT_SEQNUM (event);

}

/**

 * gst_event_set_seqnum:

 * @event: A #GstEvent.

 * @seqnum: A sequence number.

 *

 * Set the sequence number of a event.

 *

 * This function might be called by the creator of a event to indicate that the

 * event relates to other events or messages. See gst_event_get_seqnum() for

 * more information.

 *

 * MT safe.

 */

void

gst_event_set_seqnum (GstEvent * event, guint32 seqnum)

{

  g_return_if_fail (GST_IS_EVENT (event));

  GST_EVENT_SEQNUM (event) = seqnum;

}

/**

 * gst_event_get_running_time_offset:

 * @event: A #GstEvent.

 *

 * Retrieve the accumulated running time offset of the event.

 *

 * Events passing through #GstPads that have a running time

 * offset set via gst_pad_set_offset() will get their offset

 * adjusted according to the pad's offset.

 *

 * If the event contains any information that related to the

 * running time, this information will need to be updated

 * before usage with this offset.

 *

 * Returns: The event's running time offset

 *

 * MT safe.

 *

 * Since: 1.4

 */

gint64

gst_event_get_running_time_offset (GstEvent * event)

{

  g_return_val_if_fail (GST_IS_EVENT (event), 0);

  return ((GstEventImpl *) event)->running_time_offset;

}

/**

 * gst_event_set_running_time_offset:

 * @event: A #GstEvent.

 * @offset: A the new running time offset

 *

 * Set the running time offset of a event. See

 * gst_event_get_running_time_offset() for more information.

 *

 * MT safe.

 *

 * Since: 1.4

 */

void

gst_event_set_running_time_offset (GstEvent * event, gint64 offset)

{

  g_return_if_fail (GST_IS_EVENT (event));

  ((GstEventImpl *) event)->running_time_offset = offset;

}

/**

 * gst_event_new_flush_start:

 *

 * Allocate a new flush start event. The flush start event can be sent

 * upstream and downstream and travels out-of-bounds with the dataflow.

 *

 * It marks pads as being flushing and will make them return

 * #GST_FLOW_FLUSHING when used for data flow with gst_pad_push(),

 * gst_pad_chain(), gst_pad_get_range() and gst_pad_pull_range().

 * Any event (except a #GST_EVENT_FLUSH_STOP) received

 * on a flushing pad will return %FALSE immediately.

 *

 * Elements should unlock any blocking functions and exit their streaming

 * functions as fast as possible when this event is received.

 *

 * This event is typically generated after a seek to flush out all queued data

 * in the pipeline so that the new media is played as soon as possible.

 *

 * Returns: (transfer full): a new flush start event.

 */

GstEvent *

gst_event_new_flush_start (void)

{

  return gst_event_new_custom (GST_EVENT_FLUSH_START, NULL);

}

/**

 * gst_event_new_flush_stop:

 * @reset_time: if time should be reset

 *

 * Allocate a new flush stop event. The flush stop event can be sent

 * upstream and downstream and travels serialized with the dataflow.

 * It is typically sent after sending a FLUSH_START event to make the

 * pads accept data again.

 *

 * Elements can process this event synchronized with the dataflow since

 * the preceding FLUSH_START event stopped the dataflow.

 *

 * This event is typically generated to complete a seek and to resume

 * dataflow.

 *

 * Returns: (transfer full): a new flush stop event.

 */

GstEvent *

gst_event_new_flush_stop (gboolean reset_time)

{

  GstEvent *event;

  GST_CAT_INFO (GST_CAT_EVENT, "creating flush stop %d", reset_time);

  event = gst_event_new_custom (GST_EVENT_FLUSH_STOP,

      gst_structure_new_id (GST_QUARK (EVENT_FLUSH_STOP),

          GST_QUARK (RESET_TIME), G_TYPE_BOOLEAN, reset_time, NULL));

  return event;

}

/**

 * gst_event_parse_flush_stop:

 * @event: The event to parse

 * @reset_time: (out): if time should be reset

 *

 * Parse the FLUSH_STOP event and retrieve the @reset_time member.

 */

void

gst_event_parse_flush_stop (GstEvent * event, gboolean * reset_time)

{

  GstStructure *structure;

  g_return_if_fail (GST_IS_EVENT (event));

  g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_FLUSH_STOP);

  structure = GST_EVENT_STRUCTURE (event);

  if (G_LIKELY (reset_time))

    *reset_time =

        g_value_get_boolean (gst_structure_id_get_value (structure,

            GST_QUARK (RESET_TIME)));

}

/**

 * gst_event_new_select_streams:

 * @streams: (element-type utf8) (transfer none): the list of streams to

 * activate

 *

 * Allocate a new select-streams event.

 *

 * The select-streams event requests the specified @streams to be activated.

 *

 * The list of @streams corresponds to the "Stream ID" of each stream to be

 * activated. Those ID can be obtained via the #GstStream objects present

 * in #GST_EVENT_STREAM_START, #GST_EVENT_STREAM_COLLECTION or

 * #GST_MESSAGE_STREAM_COLLECTION.

 *

 * Note: The list of @streams can not be empty.

 *

 * Returns: (transfer full): a new select-streams event or %NULL in case of

 * an error (like an empty streams list).

 *

 * Since: 1.10

 */

GstEvent *

gst_event_new_select_streams (GList * streams)

{

  GstEvent *event;

  GValue val = G_VALUE_INIT;

  GstStructure *struc;

  GList *tmpl;

  g_return_val_if_fail (streams != NULL, NULL);

  GST_CAT_INFO (GST_CAT_EVENT, "Creating new select-streams event");

  struc = gst_structure_new_id_empty (GST_QUARK (EVENT_SELECT_STREAMS));

  g_value_init (&val, GST_TYPE_LIST);

  /* Fill struc with streams */

  for (tmpl = streams; tmpl; tmpl = tmpl->next) {

    GValue strval = G_VALUE_INIT;

    const gchar *str = (const gchar *) tmpl->data;

    g_value_init (&strval, G_TYPE_STRING);

    g_value_set_string (&strval, str);

    gst_value_list_append_and_take_value (&val, &strval);

  }

  gst_structure_id_take_value (struc, GST_QUARK (STREAMS), &val;;

  event = gst_event_new_custom (GST_EVENT_SELECT_STREAMS, struc);

  return event;

}

/**

 * gst_event_parse_select_streams:

 * @event: The event to parse

 * @streams: (out) (element-type utf8) (transfer full): the streams

 *

 * Parse the SELECT_STREAMS event and retrieve the contained streams.

 *

 * Since: 1.10

 */

void

gst_event_parse_select_streams (GstEvent * event, GList ** streams)

{

  GstStructure *structure;

  GList *res = NULL;

  g_return_if_fail (GST_IS_EVENT (event));

  g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SELECT_STREAMS);

  structure = GST_EVENT_STRUCTURE (event);

  if (G_LIKELY (streams)) {

    const GValue *vlist =

        gst_structure_id_get_value (structure, GST_QUARK (STREAMS));

    guint i, sz = gst_value_list_get_size (vlist);

    for (i = 0; i < sz; i++) {

      const GValue *strv = gst_value_list_get_value (vlist, i);

      res = g_list_append (res, g_value_dup_string (strv));

    }

    *streams = res;

  }

}

/**

 * gst_event_new_stream_group_done:

 * @group_id: the group id of the stream group which is ending

 *

 * Create a new Stream Group Done event. The stream-group-done event can

 * only travel downstream synchronized with the buffer flow. Elements

 * that receive the event on a pad should handle it mostly like EOS,

 * and emit any data or pending buffers that would depend on more data

 * arriving and unblock, since there won't be any more data.

 *

 * This event is followed by EOS at some point in the future, and is

 * generally used when switching pads - to unblock downstream so that

 * new pads can be exposed before sending EOS on the existing pads.

 *

 * Returns: (transfer full): the new stream-group-done event.

 *

 * Since: 1.10

 */

GstEvent *

gst_event_new_stream_group_done (guint group_id)

{

  GstStructure *s;

  s = gst_structure_new_id (GST_QUARK (EVENT_STREAM_GROUP_DONE),

      GST_QUARK (GROUP_ID), G_TYPE_UINT, group_id, NULL);

  return gst_event_new_custom (GST_EVENT_STREAM_GROUP_DONE, s);

}

/**

 * gst_event_parse_stream_group_done:

 * @event: a stream-group-done event.

 * @group_id: (out): address of variable to store the group id into

 *

 * Parse a stream-group-done @event and store the result in the given

 * @group_id location.

 *

 * Since: 1.10

 */

void

gst_event_parse_stream_group_done (GstEvent * event, guint * group_id)

{

  g_return_if_fail (event != NULL);

  g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_STREAM_GROUP_DONE);

  if (group_id) {

    gst_structure_id_get (GST_EVENT_STRUCTURE (event),

        GST_QUARK (GROUP_ID), G_TYPE_UINT, group_id, NULL);

  }

}

/**

 * gst_event_new_eos:

 *

 * Create a new EOS event. The eos event can only travel downstream

 * synchronized with the buffer flow. Elements that receive the EOS

 * event on a pad can return #GST_FLOW_EOS as a #GstFlowReturn

 * when data after the EOS event arrives.

 *

 * The EOS event will travel down to the sink elements in the pipeline

 * which will then post the #GST_MESSAGE_EOS on the bus after they have

 * finished playing any buffered data.

 *

 * When all sinks have posted an EOS message, an EOS message is

 * forwarded to the application.

 *

 * The EOS event itself will not cause any state transitions of the pipeline.

 *

 * Returns: (transfer full): the new EOS event.

 */

GstEvent *

gst_event_new_eos (void)

{

  return gst_event_new_custom (GST_EVENT_EOS, NULL);

}

/**

 * gst_event_new_gap:

 * @timestamp: the start time (pts) of the gap

 * @duration: the duration of the gap

 *

 * Create a new GAP event. A gap event can be thought of as conceptually

 * equivalent to a buffer to signal that there is no data for a certain

 * amount of time. This is useful to signal a gap to downstream elements

 * which may wait for data, such as muxers or mixers or overlays, especially

 * for sparse streams such as subtitle streams.

 *

 * Returns: (transfer full): the new GAP event.

 */

GstEvent *

gst_event_new_gap (GstClockTime timestamp, GstClockTime duration)

{

  GstEvent *event;

  g_return_val_if_fail (GST_CLOCK_TIME_IS_VALID (timestamp), NULL);

  GST_CAT_TRACE (GST_CAT_EVENT, "creating gap %" GST_TIME_FORMAT " - "

      "%" GST_TIME_FORMAT " (duration: %" GST_TIME_FORMAT ")",

      GST_TIME_ARGS (timestamp), GST_TIME_ARGS (timestamp + duration),

      GST_TIME_ARGS (duration));

  event = gst_event_new_custom (GST_EVENT_GAP,

      gst_structure_new_id (GST_QUARK (EVENT_GAP),

          GST_QUARK (TIMESTAMP), GST_TYPE_CLOCK_TIME, timestamp,

          GST_QUARK (DURATION), GST_TYPE_CLOCK_TIME, duration, NULL));

  return event;

}

/**

 * gst_event_parse_gap:

 * @event: a #GstEvent of type #GST_EVENT_GAP

 * @timestamp: (out) (allow-none): location where to store the

 *     start time (pts) of the gap, or %NULL

 * @duration: (out) (allow-none): location where to store the duration of

 *     the gap, or %NULL

 *

 * Extract timestamp and duration from a new GAP event.

 */

void

gst_event_parse_gap (GstEvent * event, GstClockTime * timestamp,

    GstClockTime * duration)

{

  GstStructure *structure;

  g_return_if_fail (GST_IS_EVENT (event));

  g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_GAP);

  structure = GST_EVENT_STRUCTURE (event);

  gst_structure_id_get (structure,

      GST_QUARK (TIMESTAMP), GST_TYPE_CLOCK_TIME, timestamp,

      GST_QUARK (DURATION), GST_TYPE_CLOCK_TIME, duration, NULL);

}

/**

 * gst_event_new_caps:

 * @caps: (transfer none): a #GstCaps

 *

 * Create a new CAPS event for @caps. The caps event can only travel downstream

 * synchronized with the buffer flow and contains the format of the buffers

 * that will follow after the event.

 *

 * Returns: (transfer full) (nullable): the new CAPS event.

 */

GstEvent *

gst_event_new_caps (GstCaps * caps)

{

  GstEvent *event;

  g_return_val_if_fail (caps != NULL, NULL);

  g_return_val_if_fail (gst_caps_is_fixed (caps), NULL);

  GST_CAT_INFO (GST_CAT_EVENT, "creating caps event %" GST_PTR_FORMAT, caps);

  event = gst_event_new_custom (GST_EVENT_CAPS,

      gst_structure_new_id (GST_QUARK (EVENT_CAPS),

          GST_QUARK (CAPS), GST_TYPE_CAPS, caps, NULL));

  return event;

}

/**

 * gst_event_parse_caps:

 * @event: The event to parse

 * @caps: (out) (transfer none): A pointer to the caps

 *

 * Get the caps from @event. The caps remains valid as long as @event remains

 * valid.

 */

void

gst_event_parse_caps (GstEvent * event, GstCaps ** caps)

{

  GstStructure *structure;

  g_return_if_fail (GST_IS_EVENT (event));

  g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_CAPS);

  structure = GST_EVENT_STRUCTURE (event);

  if (G_LIKELY (caps))

    *caps =

        g_value_get_boxed (gst_structure_id_get_value (structure,

            GST_QUARK (CAPS)));

}

/**

 * gst_event_new_segment:

 * @segment: (transfer none): a #GstSegment

 *

 * Create a new SEGMENT event for @segment. The segment event can only travel

 * downstream synchronized with the buffer flow and contains timing information

 * and playback properties for the buffers that will follow.

 *

 * The segment event marks the range of buffers to be processed. All

 * data not within the segment range is not to be processed. This can be

 * used intelligently by plugins to apply more efficient methods of skipping

 * unneeded data. The valid range is expressed with the @start and @stop

 * values.

 *

 * The time value of the segment is used in conjunction with the start

 * value to convert the buffer timestamps into the stream time. This is

 * usually done in sinks to report the current stream_time.

 * @time represents the stream_time of a buffer carrying a timestamp of

 * @start. @time cannot be -1.

 *

 * @start cannot be -1, @stop can be -1. If there

 * is a valid @stop given, it must be greater or equal the @start, including

 * when the indicated playback @rate is < 0.

 *

 * The @applied_rate value provides information about any rate adjustment that

 * has already been made to the timestamps and content on the buffers of the

 * stream. (@rate * @applied_rate) should always equal the rate that has been

 * requested for playback. For example, if an element has an input segment

 * with intended playback @rate of 2.0 and applied_rate of 1.0, it can adjust

 * incoming timestamps and buffer content by half and output a segment event

 * with @rate of 1.0 and @applied_rate of 2.0

 *

 * After a segment event, the buffer stream time is calculated with:

 *

 *   time + (TIMESTAMP(buf) - start) * ABS (rate * applied_rate)