2 * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
3 * 2000 Wim Taymans <wim.taymans@chello.be>
4 * 2005 Wim Taymans <wim@fluendo.com>
6 * gstevent.c: GstEvent subsystem
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Library General Public
10 * License as published by the Free Software Foundation; either
11 * version 2 of the License, or (at your option) any later version.
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Library General Public License for more details.
18 * You should have received a copy of the GNU Library General Public
19 * License along with this library; if not, write to the
20 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
21 * Boston, MA 02111-1307, USA.
26 * @short_description: Structure describing events that are passed up and down
28 * @see_also: #GstPad, #GstElement
30 * The event class provides factory methods to construct events for sending
31 * and functions to query (parse) received events.
33 * Events are usually created with gst_event_new_*() which takes event-type
34 * specific parameters as arguments.
35 * To send an event application will usually use gst_element_send_event() and
36 * elements will use gst_pad_send_event() or gst_pad_push_event().
37 * The event should be unreffed with gst_event_unref() if it has not been sent.
39 * Events that have been received can be parsed with their respective
40 * gst_event_parse_*() functions. It is valid to pass %NULL for unwanted details.
42 * Events are passed between elements in parallel to the data stream. Some events
43 * are serialized with buffers, others are not. Some events only travel downstream,
44 * others only upstream. Some events can travel both upstream and downstream.
46 * The events are used to signal special conditions in the datastream such as
47 * EOS (end of stream) or the start of a new stream-segment.
48 * Events are also used to flush the pipeline of any pending data.
50 * Most of the event API is used inside plugins. Applications usually only
51 * construct and use seek events.
52 * To do that gst_event_new_seek() is used to create a seek event. It takes
53 * the needed parameters to specify seeking time and mode.
55 * <title>performing a seek on a pipeline</title>
60 * // construct a seek event to play the media from second 2 to 5, flush
61 * // the pipeline to decrease latency.
62 * event = gst_event_new_seek (1.0,
64 * GST_SEEK_FLAG_FLUSH,
65 * GST_SEEK_TYPE_SET, 2 * GST_SECOND,
66 * GST_SEEK_TYPE_SET, 5 * GST_SECOND);
68 * result = gst_element_send_event (pipeline, event);
70 * g_warning ("seek failed");
75 * Last reviewed on 2006-09-6 (0.10.10)
79 #include "gst_private.h"
80 #include <string.h> /* memcpy */
84 #include "gstenumtypes.h"
89 GType _gst_event_type = 0;
95 GstStructure *structure;
98 #define GST_EVENT_STRUCTURE(e) (((GstEventImpl *)(e))->structure)
107 static GstEventQuarks event_quarks[] = {
108 {GST_EVENT_UNKNOWN, "unknown", 0},
109 {GST_EVENT_FLUSH_START, "flush-start", 0},
110 {GST_EVENT_FLUSH_STOP, "flush-stop", 0},
111 {GST_EVENT_STREAM_START, "stream-start", 0},
112 {GST_EVENT_CAPS, "caps", 0},
113 {GST_EVENT_STREAM_CONFIG, "stream-config", 0},
114 {GST_EVENT_SEGMENT, "segment", 0},
115 {GST_EVENT_TAG, "tag", 0},
116 {GST_EVENT_BUFFERSIZE, "buffersize", 0},
117 {GST_EVENT_SINK_MESSAGE, "sink-message", 0},
118 {GST_EVENT_EOS, "eos", 0},
119 {GST_EVENT_SEGMENT_DONE, "segment-done", 0},
120 {GST_EVENT_GAP, "gap", 0},
121 {GST_EVENT_QOS, "qos", 0},
122 {GST_EVENT_SEEK, "seek", 0},
123 {GST_EVENT_NAVIGATION, "navigation", 0},
124 {GST_EVENT_LATENCY, "latency", 0},
125 {GST_EVENT_STEP, "step", 0},
126 {GST_EVENT_RECONFIGURE, "reconfigure", 0},
127 {GST_EVENT_CUSTOM_UPSTREAM, "custom-upstream", 0},
128 {GST_EVENT_CUSTOM_DOWNSTREAM, "custom-downstream", 0},
129 {GST_EVENT_CUSTOM_DOWNSTREAM_OOB, "custom-downstream-oob", 0},
130 {GST_EVENT_CUSTOM_DOWNSTREAM_STICKY, "custom-downstream-sticky", 0},
131 {GST_EVENT_CUSTOM_BOTH, "custom-both", 0},
132 {GST_EVENT_CUSTOM_BOTH_OOB, "custom-both-oob", 0},
137 GST_DEFINE_MINI_OBJECT_TYPE (GstEvent, gst_event);
140 _priv_gst_event_initialize (void)
144 _gst_event_type = gst_event_get_type ();
146 g_type_class_ref (gst_seek_flags_get_type ());
147 g_type_class_ref (gst_seek_type_get_type ());
149 for (i = 0; event_quarks[i].name; i++) {
150 event_quarks[i].quark = g_quark_from_static_string (event_quarks[i].name);
155 * gst_event_type_get_name:
156 * @type: the event type
158 * Get a printable name for the given event type. Do not modify or free.
160 * Returns: a reference to the static name of the event.
163 gst_event_type_get_name (GstEventType type)
167 for (i = 0; event_quarks[i].name; i++) {
168 if (type == event_quarks[i].type)
169 return event_quarks[i].name;
175 * gst_event_type_to_quark:
176 * @type: the event type
178 * Get the unique quark for the given event type.
180 * Returns: the quark associated with the event type
183 gst_event_type_to_quark (GstEventType type)
187 for (i = 0; event_quarks[i].name; i++) {
188 if (type == event_quarks[i].type)
189 return event_quarks[i].quark;
195 * gst_event_type_get_flags:
196 * @type: a #GstEventType
198 * Gets the #GstEventTypeFlags associated with @type.
200 * Returns: a #GstEventTypeFlags.
203 gst_event_type_get_flags (GstEventType type)
205 GstEventTypeFlags ret;
207 ret = type & ((1 << GST_EVENT_NUM_SHIFT) - 1);
213 _gst_event_free (GstEvent * event)
217 g_return_if_fail (event != NULL);
218 g_return_if_fail (GST_IS_EVENT (event));
220 GST_CAT_LOG (GST_CAT_EVENT, "freeing event %p type %s", event,
221 GST_EVENT_TYPE_NAME (event));
223 s = GST_EVENT_STRUCTURE (event);
226 gst_structure_set_parent_refcount (s, NULL);
227 gst_structure_free (s);
230 g_slice_free1 (GST_MINI_OBJECT_SIZE (event), event);
233 static void gst_event_init (GstEventImpl * event, gsize size,
237 _gst_event_copy (GstEvent * event)
242 copy = g_slice_new0 (GstEventImpl);
244 gst_event_init (copy, sizeof (GstEventImpl), GST_EVENT_TYPE (event));
246 GST_EVENT_TIMESTAMP (copy) = GST_EVENT_TIMESTAMP (event);
247 GST_EVENT_SEQNUM (copy) = GST_EVENT_SEQNUM (event);
249 s = GST_EVENT_STRUCTURE (event);
251 GST_EVENT_STRUCTURE (copy) = gst_structure_copy (s);
252 gst_structure_set_parent_refcount (GST_EVENT_STRUCTURE (copy),
253 ©->event.mini_object.refcount);
255 return GST_EVENT_CAST (copy);
259 gst_event_init (GstEventImpl * event, gsize size, GstEventType type)
261 gst_mini_object_init (GST_MINI_OBJECT_CAST (event), _gst_event_type, size);
263 event->event.mini_object.copy = (GstMiniObjectCopyFunction) _gst_event_copy;
264 event->event.mini_object.free = (GstMiniObjectFreeFunction) _gst_event_free;
266 GST_EVENT_TYPE (event) = type;
267 GST_EVENT_TIMESTAMP (event) = GST_CLOCK_TIME_NONE;
268 GST_EVENT_SEQNUM (event) = gst_util_seqnum_next ();
272 gst_event_new (GstEventType type)
276 event = g_slice_new0 (GstEventImpl);
278 GST_CAT_DEBUG (GST_CAT_EVENT, "creating new event %p %s %d", event,
279 gst_event_type_get_name (type), type);
281 gst_event_init (event, sizeof (GstEventImpl), type);
283 return GST_EVENT_CAST (event);
287 * gst_event_new_custom:
288 * @type: The type of the new event
289 * @structure: (transfer full): the structure for the event. The event will
290 * take ownership of the structure.
292 * Create a new custom-typed event. This can be used for anything not
293 * handled by other event-specific functions to pass an event to another
296 * Make sure to allocate an event type with the #GST_EVENT_MAKE_TYPE macro,
297 * assigning a free number and filling in the correct direction and
298 * serialization flags.
300 * New custom events can also be created by subclassing the event type if
303 * Returns: (transfer full): the new custom event.
306 gst_event_new_custom (GstEventType type, GstStructure * structure)
310 /* structure must not have a parent */
311 event = gst_event_new (type);
313 if (!gst_structure_set_parent_refcount (structure,
314 &event->mini_object.refcount))
317 GST_EVENT_STRUCTURE (event) = structure;
324 gst_event_unref (event);
325 g_warning ("structure is already owned by another object");
331 * gst_event_get_structure:
332 * @event: The #GstEvent.
334 * Access the structure of the event.
336 * Returns: The structure of the event. The structure is still
337 * owned by the event, which means that you should not free it and
338 * that the pointer becomes invalid when you free the event.
343 gst_event_get_structure (GstEvent * event)
345 g_return_val_if_fail (GST_IS_EVENT (event), NULL);
347 return GST_EVENT_STRUCTURE (event);
351 * gst_event_writable_structure:
352 * @event: The #GstEvent.
354 * Get a writable version of the structure.
356 * Returns: The structure of the event. The structure is still
357 * owned by the event, which means that you should not free it and
358 * that the pointer becomes invalid when you free the event.
359 * This function checks if @event is writable and will never return NULL.
364 gst_event_writable_structure (GstEvent * event)
366 GstStructure *structure;
368 g_return_val_if_fail (GST_IS_EVENT (event), NULL);
369 g_return_val_if_fail (gst_event_is_writable (event), NULL);
371 structure = GST_EVENT_STRUCTURE (event);
373 if (structure == NULL) {
375 gst_structure_new_id_empty (gst_event_type_to_quark (GST_EVENT_TYPE
377 gst_structure_set_parent_refcount (structure, &event->mini_object.refcount);
378 GST_EVENT_STRUCTURE (event) = structure;
384 * gst_event_has_name:
385 * @event: The #GstEvent.
386 * @name: name to check
388 * Checks if @event has the given @name. This function is usually used to
389 * check the name of a custom event.
391 * Returns: %TRUE if @name matches the name of the event structure.
396 gst_event_has_name (GstEvent * event, const gchar * name)
398 g_return_val_if_fail (GST_IS_EVENT (event), FALSE);
400 if (GST_EVENT_STRUCTURE (event) == NULL)
403 return gst_structure_has_name (GST_EVENT_STRUCTURE (event), name);
407 * gst_event_get_seqnum:
408 * @event: A #GstEvent.
410 * Retrieve the sequence number of a event.
412 * Events have ever-incrementing sequence numbers, which may also be set
413 * explicitly via gst_event_set_seqnum(). Sequence numbers are typically used to
414 * indicate that a event corresponds to some other set of events or messages,
415 * for example an EOS event corresponding to a SEEK event. It is considered good
416 * practice to make this correspondence when possible, though it is not
419 * Note that events and messages share the same sequence number incrementor;
420 * two events or messages will never have the same sequence number unless
421 * that correspondence was made explicitly.
423 * Returns: The event's sequence number.
430 gst_event_get_seqnum (GstEvent * event)
432 g_return_val_if_fail (GST_IS_EVENT (event), -1);
434 return GST_EVENT_SEQNUM (event);
438 * gst_event_set_seqnum:
439 * @event: A #GstEvent.
440 * @seqnum: A sequence number.
442 * Set the sequence number of a event.
444 * This function might be called by the creator of a event to indicate that the
445 * event relates to other events or messages. See gst_event_get_seqnum() for
453 gst_event_set_seqnum (GstEvent * event, guint32 seqnum)
455 g_return_if_fail (GST_IS_EVENT (event));
457 GST_EVENT_SEQNUM (event) = seqnum;
460 /* FIXME 0.11: It would be nice to have flush events
461 * that don't reset the running time in the sinks
465 * gst_event_new_flush_start:
467 * Allocate a new flush start event. The flush start event can be sent
468 * upstream and downstream and travels out-of-bounds with the dataflow.
470 * It marks pads as being flushing and will make them return
471 * #GST_FLOW_WRONG_STATE when used for data flow with gst_pad_push(),
472 * gst_pad_chain(), gst_pad_alloc_buffer(), gst_pad_get_range() and
473 * gst_pad_pull_range(). Any event (except a #GST_EVENT_FLUSH_STOP) received
474 * on a flushing pad will return %FALSE immediately.
476 * Elements should unlock any blocking functions and exit their streaming
477 * functions as fast as possible when this event is received.
479 * This event is typically generated after a seek to flush out all queued data
480 * in the pipeline so that the new media is played as soon as possible.
482 * Returns: (transfer full): a new flush start event.
485 gst_event_new_flush_start (void)
487 return gst_event_new (GST_EVENT_FLUSH_START);
491 * gst_event_new_flush_stop:
492 * @reset_time: if time should be reset
494 * Allocate a new flush stop event. The flush stop event can be sent
495 * upstream and downstream and travels serialized with the dataflow.
496 * It is typically sent after sending a FLUSH_START event to make the
497 * pads accept data again.
499 * Elements can process this event synchronized with the dataflow since
500 * the preceeding FLUSH_START event stopped the dataflow.
502 * This event is typically generated to complete a seek and to resume
505 * Returns: (transfer full): a new flush stop event.
508 gst_event_new_flush_stop (gboolean reset_time)
512 GST_CAT_INFO (GST_CAT_EVENT, "creating flush stop %d", reset_time);
514 event = gst_event_new_custom (GST_EVENT_FLUSH_STOP,
515 gst_structure_new_id (GST_QUARK (EVENT_FLUSH_STOP),
516 GST_QUARK (RESET_TIME), G_TYPE_BOOLEAN, reset_time, NULL));
522 * gst_event_parse_flush_stop:
523 * @event: The event to parse
524 * @reset_time: (out): if time should be reset
526 * Parse the FLUSH_STOP event and retrieve the @reset_time member.
529 gst_event_parse_flush_stop (GstEvent * event, gboolean * reset_time)
531 GstStructure *structure;
533 g_return_if_fail (GST_IS_EVENT (event));
534 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_FLUSH_STOP);
536 structure = GST_EVENT_STRUCTURE (event);
537 if (G_LIKELY (reset_time))
539 g_value_get_boolean (gst_structure_id_get_value (structure,
540 GST_QUARK (RESET_TIME)));
546 * Create a new EOS event. The eos event can only travel downstream
547 * synchronized with the buffer flow. Elements that receive the EOS
548 * event on a pad can return #GST_FLOW_UNEXPECTED as a #GstFlowReturn
549 * when data after the EOS event arrives.
551 * The EOS event will travel down to the sink elements in the pipeline
552 * which will then post the #GST_MESSAGE_EOS on the bus after they have
553 * finished playing any buffered data.
555 * When all sinks have posted an EOS message, an EOS message is
556 * forwarded to the application.
558 * The EOS event itself will not cause any state transitions of the pipeline.
560 * Returns: (transfer full): the new EOS event.
563 gst_event_new_eos (void)
565 return gst_event_new (GST_EVENT_EOS);
569 * gst_event_new_caps:
570 * @caps: (transfer none): a #GstCaps
572 * Create a new CAPS event for @caps. The caps event can only travel downstream
573 * synchronized with the buffer flow and contains the format of the buffers
574 * that will follow after the event.
576 * Returns: (transfer full): the new CAPS event.
579 gst_event_new_caps (GstCaps * caps)
583 g_return_val_if_fail (caps != NULL, NULL);
584 g_return_val_if_fail (gst_caps_is_fixed (caps), NULL);
586 GST_CAT_INFO (GST_CAT_EVENT, "creating caps event %" GST_PTR_FORMAT, caps);
588 event = gst_event_new_custom (GST_EVENT_CAPS,
589 gst_structure_new_id (GST_QUARK (EVENT_CAPS),
590 GST_QUARK (CAPS), GST_TYPE_CAPS, caps, NULL));
596 * gst_event_parse_caps:
597 * @event: The event to parse
598 * @caps: (out): A pointer to the caps
600 * Get the caps from @event. The caps remains valid as long as @event remains
604 gst_event_parse_caps (GstEvent * event, GstCaps ** caps)
606 GstStructure *structure;
608 g_return_if_fail (GST_IS_EVENT (event));
609 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_CAPS);
611 structure = GST_EVENT_STRUCTURE (event);
614 g_value_get_boxed (gst_structure_id_get_value (structure,
619 * gst_event_new_stream_config:
620 * @flags: the stream config flags
622 * Create a new STREAM CONFIG event. The stream config event travels
623 * downstream synchronized with the buffer flow and contains stream
624 * configuration information for the stream, such as stream-headers
625 * or codec-data. It is optional and should be sent after the CAPS
628 * Returns: (transfer full): the new STREAM CONFIG event.
631 gst_event_new_stream_config (GstStreamConfigFlags flags)
635 GST_CAT_INFO (GST_CAT_EVENT, "creating stream info event, flags=0x%x", flags);
637 event = gst_event_new_custom (GST_EVENT_STREAM_CONFIG,
638 gst_structure_new_id (GST_QUARK (EVENT_STREAM_CONFIG),
639 GST_QUARK (FLAGS), GST_TYPE_STREAM_CONFIG_FLAGS, flags, NULL));
645 * gst_event_parse_stream_config:
646 * @event: The event to parse
647 * @flags: (out): a pointer to a variable to store the stream config flags
649 * Get the stream config flags from @event.
652 gst_event_parse_stream_config (GstEvent * event, GstStreamConfigFlags * flags)
654 GstStructure *structure;
656 g_return_if_fail (GST_IS_EVENT (event));
657 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_STREAM_CONFIG);
659 structure = GST_EVENT_STRUCTURE (event);
660 if (G_LIKELY (flags != NULL)) {
662 g_value_get_enum (gst_structure_id_get_value (structure,
668 * gst_event_set_stream_config_codec_data:
669 * @event: a stream config event
670 * @buf: a #GstBuffer with codec data
672 * Set codec data on the stream info event to signal out of bound setup data
673 * to downstream elements. Unlike stream headers, codec data contains data
674 * that is required to interpret the data stream, but is not valid as-is
675 * inside the data stream and thus can't just be prepended to or inserted
676 * into the data stream.
679 gst_event_set_stream_config_codec_data (GstEvent * event, GstBuffer * buf)
683 g_return_if_fail (GST_IS_EVENT (event));
684 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_STREAM_CONFIG);
685 g_return_if_fail (GST_IS_BUFFER (buf) && gst_buffer_get_size (buf) > 0);
687 s = GST_EVENT_STRUCTURE (event);
688 gst_structure_id_set (s, GST_QUARK (CODEC_DATA), GST_TYPE_BUFFER, buf, NULL);
692 * gst_event_set_stream_config_codec_data:
693 * @event: a stream config event
694 * @buf: (transfer none): location where to store the #GstBuffer with codec data
696 * Extracts the codec data buffer from the stream info event. Will store
697 * %NULL in @buf if the event contains no codec data. The buffer returned
698 * will remain valid as long as @event remains valid. The caller should
699 * acquire a referenceto to @buf if needed.
702 gst_event_parse_stream_config_codec_data (GstEvent * event, GstBuffer ** buf)
707 g_return_if_fail (GST_IS_EVENT (event));
708 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_STREAM_CONFIG);
709 g_return_if_fail (buf != NULL);
711 s = GST_EVENT_STRUCTURE (event);
712 val = gst_structure_id_get_value (s, GST_QUARK (CODEC_DATA));
714 *buf = g_value_get_boxed (val);
720 * gst_event_add_stream_config_header:
721 * @event: a stream config event
722 * @buf: a #GstBuffer with stream header data
724 * Adds a stream header to the stream info event to signal stream headers to
725 * to downstream elements such as multifilesink, tcpserversink etc. Stream
726 * headers can be and should usually be prepended to the data stream at any
727 * point in the stream (which requires a streamable format), e.g. to a new
728 * client connecting, or when starting a new file segment. stream header
729 * buffers will all be used together in the order they were added to the
730 * stream config event. Stream headers are sent as buffers at the beginning
731 * of the data flow in addition to the stream config event. Elements that
732 * care about stream headers need to make sure that they don't insert or
733 * interpret these header buffers twice if they interpret them.
736 gst_event_add_stream_config_header (GstEvent * event, GstBuffer * buf)
739 GValue buf_val = { 0, };
742 g_return_if_fail (GST_IS_EVENT (event));
743 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_STREAM_CONFIG);
744 g_return_if_fail (GST_IS_BUFFER (buf) && gst_buffer_get_size (buf) > 0);
746 g_value_init (&buf_val, GST_TYPE_BUFFER);
747 g_value_set_boxed (&buf_val, buf);
749 s = GST_EVENT_STRUCTURE (event);
750 val = (GValue *) gst_structure_id_get_value (s, GST_QUARK (STREAM_HEADERS));
752 GValue new_array = { 0, };
754 g_value_init (&new_array, GST_TYPE_ARRAY);
755 gst_value_array_append_value (&new_array, &buf_val);
756 gst_structure_id_take_value (s, GST_QUARK (STREAM_HEADERS), &new_array);
758 gst_value_array_append_value (val, &buf_val);
760 g_value_unset (&buf_val);
764 * gst_event_get_n_stream_config_headers:
765 * @event: a stream config event
767 * Extract the number of stream header buffers.
769 * Returns: the number of stream header buffers attached to the stream info
773 gst_event_get_n_stream_config_headers (GstEvent * event)
779 g_return_val_if_fail (GST_IS_EVENT (event), 0);
780 g_return_val_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_STREAM_CONFIG, 0);
782 s = GST_EVENT_STRUCTURE (event);
783 val = gst_structure_id_get_value (s, GST_QUARK (STREAM_HEADERS));
786 num = gst_value_array_get_size (val);
792 * gst_event_parse_nth_stream_config_header:
793 * @event: a stream config event
794 * @index: number of the stream header to retrieve
795 * @buf: location where to store the n-th stream header #GstBuffer
797 * Retrieves the n-th stream header buffer attached to the stream config
798 * event and stores it in @buf. Will store %NULL in @buf if there is no such
802 gst_event_parse_nth_stream_config_header (GstEvent * event, guint index,
805 const GValue *val, *buf_val;
807 GstBuffer *ret = NULL;
809 g_return_if_fail (GST_IS_EVENT (event));
810 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_STREAM_CONFIG);
811 g_return_if_fail (buf != NULL);
813 s = GST_EVENT_STRUCTURE (event);
814 val = gst_structure_id_get_value (s, GST_QUARK (STREAM_HEADERS));
817 buf_val = gst_value_array_get_value (val, index);
819 ret = g_value_get_boxed (buf_val);
826 * gst_event_new_segment:
827 * @segment: (transfer none): a #GstSegment
829 * Create a new SEGMENT event for @segment. The segment event can only travel
830 * downstream synchronized with the buffer flow and contains timing information
831 * and playback properties for the buffers that will follow.
833 * The newsegment event marks the range of buffers to be processed. All
834 * data not within the segment range is not to be processed. This can be
835 * used intelligently by plugins to apply more efficient methods of skipping
836 * unneeded data. The valid range is expressed with the @start and @stop
839 * The time value of the segment is used in conjunction with the start
840 * value to convert the buffer timestamps into the stream time. This is
841 * usually done in sinks to report the current stream_time.
842 * @time represents the stream_time of a buffer carrying a timestamp of
843 * @start. @time cannot be -1.
845 * @start cannot be -1, @stop can be -1. If there
846 * is a valid @stop given, it must be greater or equal the @start, including
847 * when the indicated playback @rate is < 0.
849 * The @applied_rate value provides information about any rate adjustment that
850 * has already been made to the timestamps and content on the buffers of the
851 * stream. (@rate * @applied_rate) should always equal the rate that has been
852 * requested for playback. For example, if an element has an input segment
853 * with intended playback @rate of 2.0 and applied_rate of 1.0, it can adjust
854 * incoming timestamps and buffer content by half and output a newsegment event
855 * with @rate of 1.0 and @applied_rate of 2.0
857 * After a newsegment event, the buffer stream time is calculated with:
859 * time + (TIMESTAMP(buf) - start) * ABS (rate * applied_rate)
861 * Returns: (transfer full): the new SEGMENT event.
864 gst_event_new_segment (const GstSegment * segment)
868 g_return_val_if_fail (segment != NULL, NULL);
869 g_return_val_if_fail (segment->rate != 0.0, NULL);
870 g_return_val_if_fail (segment->applied_rate != 0.0, NULL);
871 g_return_val_if_fail (segment->format != GST_FORMAT_UNDEFINED, NULL);
873 GST_CAT_INFO (GST_CAT_EVENT, "creating segment event %" GST_SEGMENT_FORMAT,
876 event = gst_event_new_custom (GST_EVENT_SEGMENT,
877 gst_structure_new_id (GST_QUARK (EVENT_SEGMENT),
878 GST_QUARK (SEGMENT), GST_TYPE_SEGMENT, segment, NULL));
884 * gst_event_parse_segment:
885 * @event: The event to parse
886 * @segment: (out) (transfer none): a pointer to a #GstSegment
888 * Parses a segment @event and stores the result in the given @segment location.
889 * @segment remains valid only until the @event is freed. Don't modify the segment
890 * and make a copy if you want to modify it or store it for later use.
893 gst_event_parse_segment (GstEvent * event, const GstSegment ** segment)
895 GstStructure *structure;
897 g_return_if_fail (GST_IS_EVENT (event));
898 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SEGMENT);
901 structure = GST_EVENT_STRUCTURE (event);
902 *segment = g_value_get_boxed (gst_structure_id_get_value (structure,
903 GST_QUARK (SEGMENT)));
908 * gst_event_copy_segment:
909 * @event: The event to parse
910 * @segment: a pointer to a #GstSegment
912 * Parses a segment @event and copies the #GstSegment into the location
916 gst_event_copy_segment (GstEvent * event, GstSegment * segment)
918 const GstSegment *src;
920 g_return_if_fail (GST_IS_EVENT (event));
921 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SEGMENT);
924 gst_event_parse_segment (event, &src);
925 gst_segment_copy_into (src, segment);
931 * @taglist: (transfer full): metadata list. The event will take ownership
934 * Generates a metadata tag event from the given @taglist.
936 * Returns: (transfer full): a new #GstEvent
939 gst_event_new_tag (GstTagList * taglist)
941 g_return_val_if_fail (taglist != NULL, NULL);
943 return gst_event_new_custom (GST_EVENT_TAG, (GstStructure *) taglist);
947 * gst_event_parse_tag:
948 * @event: a tag event
949 * @taglist: (out) (transfer none): pointer to metadata list
951 * Parses a tag @event and stores the results in the given @taglist location.
952 * No reference to the taglist will be returned, it remains valid only until
953 * the @event is freed. Don't modify or free the taglist, make a copy if you
954 * want to modify it or store it for later use.
957 gst_event_parse_tag (GstEvent * event, GstTagList ** taglist)
959 g_return_if_fail (GST_IS_EVENT (event));
960 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_TAG);
963 *taglist = (GstTagList *) GST_EVENT_STRUCTURE (event);
966 /* buffersize event */
968 * gst_event_new_buffer_size:
969 * @format: buffer format
970 * @minsize: minimum buffer size
971 * @maxsize: maximum buffer size
972 * @async: thread behavior
974 * Create a new buffersize event. The event is sent downstream and notifies
975 * elements that they should provide a buffer of the specified dimensions.
977 * When the @async flag is set, a thread boundary is preferred.
979 * Returns: (transfer full): a new #GstEvent
982 gst_event_new_buffer_size (GstFormat format, gint64 minsize,
983 gint64 maxsize, gboolean async)
986 GstStructure *structure;
988 GST_CAT_INFO (GST_CAT_EVENT,
989 "creating buffersize format %s, minsize %" G_GINT64_FORMAT
990 ", maxsize %" G_GINT64_FORMAT ", async %d", gst_format_get_name (format),
991 minsize, maxsize, async);
993 structure = gst_structure_new_id (GST_QUARK (EVENT_BUFFER_SIZE),
994 GST_QUARK (FORMAT), GST_TYPE_FORMAT, format,
995 GST_QUARK (MINSIZE), G_TYPE_INT64, minsize,
996 GST_QUARK (MAXSIZE), G_TYPE_INT64, maxsize,
997 GST_QUARK (ASYNC), G_TYPE_BOOLEAN, async, NULL);
998 event = gst_event_new_custom (GST_EVENT_BUFFERSIZE, structure);
1004 * gst_event_parse_buffer_size:
1005 * @event: The event to query
1006 * @format: (out): A pointer to store the format in
1007 * @minsize: (out): A pointer to store the minsize in
1008 * @maxsize: (out): A pointer to store the maxsize in
1009 * @async: (out): A pointer to store the async-flag in
1011 * Get the format, minsize, maxsize and async-flag in the buffersize event.
1014 gst_event_parse_buffer_size (GstEvent * event, GstFormat * format,
1015 gint64 * minsize, gint64 * maxsize, gboolean * async)
1017 const GstStructure *structure;
1019 g_return_if_fail (GST_IS_EVENT (event));
1020 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_BUFFERSIZE);
1022 structure = GST_EVENT_STRUCTURE (event);
1024 *format = (GstFormat)
1025 g_value_get_enum (gst_structure_id_get_value (structure,
1026 GST_QUARK (FORMAT)));
1029 g_value_get_int64 (gst_structure_id_get_value (structure,
1030 GST_QUARK (MINSIZE)));
1033 g_value_get_int64 (gst_structure_id_get_value (structure,
1034 GST_QUARK (MAXSIZE)));
1037 g_value_get_boolean (gst_structure_id_get_value (structure,
1038 GST_QUARK (ASYNC)));
1042 * gst_event_new_qos:
1043 * @type: the QoS type
1044 * @proportion: the proportion of the qos message
1045 * @diff: The time difference of the last Clock sync
1046 * @timestamp: The timestamp of the buffer
1048 * Allocate a new qos event with the given values.
1049 * The QOS event is generated in an element that wants an upstream
1050 * element to either reduce or increase its rate because of
1051 * high/low CPU load or other resource usage such as network performance or
1052 * throttling. Typically sinks generate these events for each buffer
1055 * @type indicates the reason for the QoS event. #GST_QOS_TYPE_OVERFLOW is
1056 * used when a buffer arrived in time or when the sink cannot keep up with
1057 * the upstream datarate. #GST_QOS_TYPE_UNDERFLOW is when the sink is not
1058 * receiving buffers fast enough and thus has to drop late buffers.
1059 * #GST_QOS_TYPE_THROTTLE is used when the datarate is artificially limited
1060 * by the application, for example to reduce power consumption.
1062 * @proportion indicates the real-time performance of the streaming in the
1063 * element that generated the QoS event (usually the sink). The value is
1064 * generally computed based on more long term statistics about the streams
1065 * timestamps compared to the clock.
1066 * A value < 1.0 indicates that the upstream element is producing data faster
1067 * than real-time. A value > 1.0 indicates that the upstream element is not
1068 * producing data fast enough. 1.0 is the ideal @proportion value. The
1069 * proportion value can safely be used to lower or increase the quality of
1072 * @diff is the difference against the clock in running time of the last
1073 * buffer that caused the element to generate the QOS event. A negative value
1074 * means that the buffer with @timestamp arrived in time. A positive value
1075 * indicates how late the buffer with @timestamp was. When throttling is
1076 * enabled, @diff will be set to the requested throttling interval.
1078 * @timestamp is the timestamp of the last buffer that cause the element
1079 * to generate the QOS event. It is expressed in running time and thus an ever
1082 * The upstream element can use the @diff and @timestamp values to decide
1083 * whether to process more buffers. For possitive @diff, all buffers with
1084 * timestamp <= @timestamp + @diff will certainly arrive late in the sink
1085 * as well. A (negative) @diff value so that @timestamp + @diff would yield a
1086 * result smaller than 0 is not allowed.
1088 * The application can use general event probes to intercept the QoS
1089 * event and implement custom application specific QoS handling.
1091 * Returns: (transfer full): a new QOS event.
1094 gst_event_new_qos (GstQOSType type, gdouble proportion,
1095 GstClockTimeDiff diff, GstClockTime timestamp)
1098 GstStructure *structure;
1100 /* diff must be positive or timestamp + diff must be positive */
1101 g_return_val_if_fail (diff >= 0 || -diff <= timestamp, NULL);
1103 GST_CAT_LOG (GST_CAT_EVENT,
1104 "creating qos type %d, proportion %lf, diff %" G_GINT64_FORMAT
1105 ", timestamp %" GST_TIME_FORMAT, type, proportion,
1106 diff, GST_TIME_ARGS (timestamp));
1108 structure = gst_structure_new_id (GST_QUARK (EVENT_QOS),
1109 GST_QUARK (TYPE), GST_TYPE_QOS_TYPE, type,
1110 GST_QUARK (PROPORTION), G_TYPE_DOUBLE, proportion,
1111 GST_QUARK (DIFF), G_TYPE_INT64, diff,
1112 GST_QUARK (TIMESTAMP), G_TYPE_UINT64, timestamp, NULL);
1113 event = gst_event_new_custom (GST_EVENT_QOS, structure);
1119 * gst_event_parse_qos:
1120 * @event: The event to query
1121 * @type: (out): A pointer to store the QoS type in
1122 * @proportion: (out): A pointer to store the proportion in
1123 * @diff: (out): A pointer to store the diff in
1124 * @timestamp: (out): A pointer to store the timestamp in
1126 * Get the type, proportion, diff and timestamp in the qos event. See
1127 * gst_event_new_qos() for more information about the different QoS values.
1130 gst_event_parse_qos (GstEvent * event, GstQOSType * type,
1131 gdouble * proportion, GstClockTimeDiff * diff, GstClockTime * timestamp)
1133 const GstStructure *structure;
1135 g_return_if_fail (GST_IS_EVENT (event));
1136 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_QOS);
1138 structure = GST_EVENT_STRUCTURE (event);
1140 *type = (GstQOSType)
1141 g_value_get_enum (gst_structure_id_get_value (structure,
1145 g_value_get_double (gst_structure_id_get_value (structure,
1146 GST_QUARK (PROPORTION)));
1149 g_value_get_int64 (gst_structure_id_get_value (structure,
1153 g_value_get_uint64 (gst_structure_id_get_value (structure,
1154 GST_QUARK (TIMESTAMP)));
1158 * gst_event_new_seek:
1159 * @rate: The new playback rate
1160 * @format: The format of the seek values
1161 * @flags: The optional seek flags
1162 * @start_type: The type and flags for the new start position
1163 * @start: The value of the new start position
1164 * @stop_type: The type and flags for the new stop position
1165 * @stop: The value of the new stop position
1167 * Allocate a new seek event with the given parameters.
1169 * The seek event configures playback of the pipeline between @start to @stop
1170 * at the speed given in @rate, also called a playback segment.
1171 * The @start and @stop values are expressed in @format.
1173 * A @rate of 1.0 means normal playback rate, 2.0 means double speed.
1174 * Negatives values means backwards playback. A value of 0.0 for the
1175 * rate is not allowed and should be accomplished instead by PAUSING the
1178 * A pipeline has a default playback segment configured with a start
1179 * position of 0, a stop position of -1 and a rate of 1.0. The currently
1180 * configured playback segment can be queried with #GST_QUERY_SEGMENT.
1182 * @start_type and @stop_type specify how to adjust the currently configured
1183 * start and stop fields in playback segment. Adjustments can be made relative
1184 * or absolute to the last configured values. A type of #GST_SEEK_TYPE_NONE
1185 * means that the position should not be updated.
1187 * When the rate is positive and @start has been updated, playback will start
1188 * from the newly configured start position.
1190 * For negative rates, playback will start from the newly configured stop
1191 * position (if any). If the stop position if updated, it must be different from
1192 * -1 for negative rates.
1194 * It is not possible to seek relative to the current playback position, to do
1195 * this, PAUSE the pipeline, query the current playback position with
1196 * #GST_QUERY_POSITION and update the playback segment current position with a
1197 * #GST_SEEK_TYPE_SET to the desired position.
1199 * Returns: (transfer full): a new seek event.
1202 gst_event_new_seek (gdouble rate, GstFormat format, GstSeekFlags flags,
1203 GstSeekType start_type, gint64 start, GstSeekType stop_type, gint64 stop)
1206 GstStructure *structure;
1208 g_return_val_if_fail (rate != 0.0, NULL);
1210 if (format == GST_FORMAT_TIME) {
1211 GST_CAT_INFO (GST_CAT_EVENT,
1212 "creating seek rate %lf, format TIME, flags %d, "
1213 "start_type %d, start %" GST_TIME_FORMAT ", "
1214 "stop_type %d, stop %" GST_TIME_FORMAT,
1215 rate, flags, start_type, GST_TIME_ARGS (start),
1216 stop_type, GST_TIME_ARGS (stop));
1218 GST_CAT_INFO (GST_CAT_EVENT,
1219 "creating seek rate %lf, format %s, flags %d, "
1220 "start_type %d, start %" G_GINT64_FORMAT ", "
1221 "stop_type %d, stop %" G_GINT64_FORMAT,
1222 rate, gst_format_get_name (format), flags, start_type, start, stop_type,
1226 structure = gst_structure_new_id (GST_QUARK (EVENT_SEEK),
1227 GST_QUARK (RATE), G_TYPE_DOUBLE, rate,
1228 GST_QUARK (FORMAT), GST_TYPE_FORMAT, format,
1229 GST_QUARK (FLAGS), GST_TYPE_SEEK_FLAGS, flags,
1230 GST_QUARK (CUR_TYPE), GST_TYPE_SEEK_TYPE, start_type,
1231 GST_QUARK (CUR), G_TYPE_INT64, start,
1232 GST_QUARK (STOP_TYPE), GST_TYPE_SEEK_TYPE, stop_type,
1233 GST_QUARK (STOP), G_TYPE_INT64, stop, NULL);
1234 event = gst_event_new_custom (GST_EVENT_SEEK, structure);
1240 * gst_event_parse_seek:
1241 * @event: a seek event
1242 * @rate: (out): result location for the rate
1243 * @format: (out): result location for the stream format
1244 * @flags: (out): result location for the #GstSeekFlags
1245 * @start_type: (out): result location for the #GstSeekType of the start position
1246 * @start: (out): result location for the start postion expressed in @format
1247 * @stop_type: (out): result location for the #GstSeekType of the stop position
1248 * @stop: (out): result location for the stop postion expressed in @format
1250 * Parses a seek @event and stores the results in the given result locations.
1253 gst_event_parse_seek (GstEvent * event, gdouble * rate,
1254 GstFormat * format, GstSeekFlags * flags, GstSeekType * start_type,
1255 gint64 * start, GstSeekType * stop_type, gint64 * stop)
1257 const GstStructure *structure;
1259 g_return_if_fail (GST_IS_EVENT (event));
1260 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SEEK);
1262 structure = GST_EVENT_STRUCTURE (event);
1265 g_value_get_double (gst_structure_id_get_value (structure,
1268 *format = (GstFormat)
1269 g_value_get_enum (gst_structure_id_get_value (structure,
1270 GST_QUARK (FORMAT)));
1272 *flags = (GstSeekFlags)
1273 g_value_get_flags (gst_structure_id_get_value (structure,
1274 GST_QUARK (FLAGS)));
1276 *start_type = (GstSeekType)
1277 g_value_get_enum (gst_structure_id_get_value (structure,
1278 GST_QUARK (CUR_TYPE)));
1281 g_value_get_int64 (gst_structure_id_get_value (structure,
1284 *stop_type = (GstSeekType)
1285 g_value_get_enum (gst_structure_id_get_value (structure,
1286 GST_QUARK (STOP_TYPE)));
1289 g_value_get_int64 (gst_structure_id_get_value (structure,
1294 * gst_event_new_navigation:
1295 * @structure: (transfer full): description of the event. The event will take
1296 * ownership of the structure.
1298 * Create a new navigation event from the given description.
1300 * Returns: (transfer full): a new #GstEvent
1303 gst_event_new_navigation (GstStructure * structure)
1305 g_return_val_if_fail (structure != NULL, NULL);
1307 return gst_event_new_custom (GST_EVENT_NAVIGATION, structure);
1311 * gst_event_new_latency:
1312 * @latency: the new latency value
1314 * Create a new latency event. The event is sent upstream from the sinks and
1315 * notifies elements that they should add an additional @latency to the
1316 * running time before synchronising against the clock.
1318 * The latency is mostly used in live sinks and is always expressed in
1321 * Returns: (transfer full): a new #GstEvent
1326 gst_event_new_latency (GstClockTime latency)
1329 GstStructure *structure;
1331 GST_CAT_INFO (GST_CAT_EVENT,
1332 "creating latency event %" GST_TIME_FORMAT, GST_TIME_ARGS (latency));
1334 structure = gst_structure_new_id (GST_QUARK (EVENT_LATENCY),
1335 GST_QUARK (LATENCY), G_TYPE_UINT64, latency, NULL);
1336 event = gst_event_new_custom (GST_EVENT_LATENCY, structure);
1342 * gst_event_parse_latency:
1343 * @event: The event to query
1344 * @latency: (out): A pointer to store the latency in.
1346 * Get the latency in the latency event.
1351 gst_event_parse_latency (GstEvent * event, GstClockTime * latency)
1353 g_return_if_fail (GST_IS_EVENT (event));
1354 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_LATENCY);
1358 g_value_get_uint64 (gst_structure_id_get_value (GST_EVENT_STRUCTURE
1359 (event), GST_QUARK (LATENCY)));
1363 * gst_event_new_step:
1364 * @format: the format of @amount
1365 * @amount: the amount of data to step
1366 * @rate: the step rate
1367 * @flush: flushing steps
1368 * @intermediate: intermediate steps
1370 * Create a new step event. The purpose of the step event is to instruct a sink
1371 * to skip @amount (expressed in @format) of media. It can be used to implement
1372 * stepping through the video frame by frame or for doing fast trick modes.
1374 * A rate of <= 0.0 is not allowed. Pause the pipeline, for the effect of rate
1375 * = 0.0 or first reverse the direction of playback using a seek event to get
1376 * the same effect as rate < 0.0.
1378 * The @flush flag will clear any pending data in the pipeline before starting
1379 * the step operation.
1381 * The @intermediate flag instructs the pipeline that this step operation is
1382 * part of a larger step operation.
1384 * Returns: (transfer full): a new #GstEvent
1389 gst_event_new_step (GstFormat format, guint64 amount, gdouble rate,
1390 gboolean flush, gboolean intermediate)
1393 GstStructure *structure;
1395 g_return_val_if_fail (rate > 0.0, NULL);
1397 GST_CAT_INFO (GST_CAT_EVENT, "creating step event");
1399 structure = gst_structure_new_id (GST_QUARK (EVENT_STEP),
1400 GST_QUARK (FORMAT), GST_TYPE_FORMAT, format,
1401 GST_QUARK (AMOUNT), G_TYPE_UINT64, amount,
1402 GST_QUARK (RATE), G_TYPE_DOUBLE, rate,
1403 GST_QUARK (FLUSH), G_TYPE_BOOLEAN, flush,
1404 GST_QUARK (INTERMEDIATE), G_TYPE_BOOLEAN, intermediate, NULL);
1405 event = gst_event_new_custom (GST_EVENT_STEP, structure);
1411 * gst_event_parse_step:
1412 * @event: The event to query
1413 * @format: (out) (allow-none): a pointer to store the format in
1414 * @amount: (out) (allow-none): a pointer to store the amount in
1415 * @rate: (out) (allow-none): a pointer to store the rate in
1416 * @flush: (out) (allow-none): a pointer to store the flush boolean in
1417 * @intermediate: (out) (allow-none): a pointer to store the intermediate
1420 * Parse the step event.
1425 gst_event_parse_step (GstEvent * event, GstFormat * format, guint64 * amount,
1426 gdouble * rate, gboolean * flush, gboolean * intermediate)
1428 const GstStructure *structure;
1430 g_return_if_fail (GST_IS_EVENT (event));
1431 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_STEP);
1433 structure = GST_EVENT_STRUCTURE (event);
1436 (GstFormat) g_value_get_enum (gst_structure_id_get_value (structure,
1437 GST_QUARK (FORMAT)));
1439 *amount = g_value_get_uint64 (gst_structure_id_get_value (structure,
1440 GST_QUARK (AMOUNT)));
1442 *rate = g_value_get_double (gst_structure_id_get_value (structure,
1445 *flush = g_value_get_boolean (gst_structure_id_get_value (structure,
1446 GST_QUARK (FLUSH)));
1448 *intermediate = g_value_get_boolean (gst_structure_id_get_value (structure,
1449 GST_QUARK (INTERMEDIATE)));
1453 * gst_event_new_reconfigure:
1455 * Create a new reconfigure event. The purpose of the reconfingure event is
1456 * to travel upstream and make elements renegotiate their caps or reconfigure
1457 * their buffer pools. This is useful when changing properties on elements
1458 * or changing the topology of the pipeline.
1460 * Returns: (transfer full): a new #GstEvent
1465 gst_event_new_reconfigure (void)
1469 GST_CAT_INFO (GST_CAT_EVENT, "creating reconfigure event");
1471 event = gst_event_new_custom (GST_EVENT_RECONFIGURE, NULL);
1477 * gst_event_new_sink_message:
1478 * @msg: (transfer none): the #GstMessage to be posted
1480 * Create a new sink-message event. The purpose of the sink-message event is
1481 * to instruct a sink to post the message contained in the event synchronized
1484 * Returns: (transfer full): a new #GstEvent
1488 /* FIXME 0.11: take ownership of msg for consistency? */
1490 gst_event_new_sink_message (GstMessage * msg)
1493 GstStructure *structure;
1495 g_return_val_if_fail (msg != NULL, NULL);
1497 GST_CAT_INFO (GST_CAT_EVENT, "creating sink-message event");
1499 structure = gst_structure_new_id (GST_QUARK (EVENT_SINK_MESSAGE),
1500 GST_QUARK (MESSAGE), GST_TYPE_MESSAGE, msg, NULL);
1501 event = gst_event_new_custom (GST_EVENT_SINK_MESSAGE, structure);
1507 * gst_event_parse_sink_message:
1508 * @event: The event to query
1509 * @msg: (out) (transfer full): a pointer to store the #GstMessage in.
1511 * Parse the sink-message event. Unref @msg after usage.
1516 gst_event_parse_sink_message (GstEvent * event, GstMessage ** msg)
1518 const GstStructure *structure;
1520 g_return_if_fail (GST_IS_EVENT (event));
1521 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SINK_MESSAGE);
1523 structure = GST_EVENT_STRUCTURE (event);
1526 GST_MESSAGE (g_value_dup_boxed (gst_structure_id_get_value
1527 (structure, GST_QUARK (MESSAGE))));
1531 * gst_event_new_stream_start
1533 * Create a new STREAM_START event. The stream start event can only
1534 * travel downstream synchronized with the buffer flow. It is expected
1535 * to be the first event that is sent for a new stream.
1537 * Source elements, demuxers and other elements that create new streams
1538 * are supposed to send this event as the first event of a new stream. It
1539 * should not be send after a flushing seek or in similar situations
1540 * and is used to mark the beginning of a new logical stream. Elements
1541 * combining multiple streams must ensure that this event is only forwarded
1542 * downstream once and not for every single input stream.
1544 * Returns: (transfer full): the new STREAM_START event.
1547 gst_event_new_stream_start (void)
1549 return gst_event_new (GST_EVENT_STREAM_START);