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"
88 GType _gst_event_type = 0;
94 GstStructure *structure;
97 #define GST_EVENT_STRUCTURE(e) (((GstEventImpl *)(e))->structure)
106 static GstEventQuarks event_quarks[] = {
107 {GST_EVENT_UNKNOWN, "unknown", 0},
108 {GST_EVENT_FLUSH_START, "flush-start", 0},
109 {GST_EVENT_FLUSH_STOP, "flush-stop", 0},
110 {GST_EVENT_STREAM_START, "stream-start", 0},
111 {GST_EVENT_CAPS, "caps", 0},
112 {GST_EVENT_STREAM_CONFIG, "stream-config", 0},
113 {GST_EVENT_SEGMENT, "segment", 0},
114 {GST_EVENT_TAG, "tag", 0},
115 {GST_EVENT_BUFFERSIZE, "buffersize", 0},
116 {GST_EVENT_SINK_MESSAGE, "sink-message", 0},
117 {GST_EVENT_EOS, "eos", 0},
118 {GST_EVENT_SEGMENT_DONE, "segment-done", 0},
119 {GST_EVENT_QOS, "qos", 0},
120 {GST_EVENT_SEEK, "seek", 0},
121 {GST_EVENT_NAVIGATION, "navigation", 0},
122 {GST_EVENT_LATENCY, "latency", 0},
123 {GST_EVENT_STEP, "step", 0},
124 {GST_EVENT_RECONFIGURE, "reconfigure", 0},
125 {GST_EVENT_CUSTOM_UPSTREAM, "custom-upstream", 0},
126 {GST_EVENT_CUSTOM_DOWNSTREAM, "custom-downstream", 0},
127 {GST_EVENT_CUSTOM_DOWNSTREAM_OOB, "custom-downstream-oob", 0},
128 {GST_EVENT_CUSTOM_DOWNSTREAM_STICKY, "custom-downstream-sticky", 0},
129 {GST_EVENT_CUSTOM_BOTH, "custom-both", 0},
130 {GST_EVENT_CUSTOM_BOTH_OOB, "custom-both-oob", 0},
135 GST_DEFINE_MINI_OBJECT_TYPE (GstEvent, gst_event);
138 _priv_gst_event_initialize (void)
142 _gst_event_type = gst_event_get_type ();
144 g_type_class_ref (gst_seek_flags_get_type ());
145 g_type_class_ref (gst_seek_type_get_type ());
147 for (i = 0; event_quarks[i].name; i++) {
148 event_quarks[i].quark = g_quark_from_static_string (event_quarks[i].name);
153 * gst_event_type_get_name:
154 * @type: the event type
156 * Get a printable name for the given event type. Do not modify or free.
158 * Returns: a reference to the static name of the event.
161 gst_event_type_get_name (GstEventType type)
165 for (i = 0; event_quarks[i].name; i++) {
166 if (type == event_quarks[i].type)
167 return event_quarks[i].name;
173 * gst_event_type_to_quark:
174 * @type: the event type
176 * Get the unique quark for the given event type.
178 * Returns: the quark associated with the event type
181 gst_event_type_to_quark (GstEventType type)
185 for (i = 0; event_quarks[i].name; i++) {
186 if (type == event_quarks[i].type)
187 return event_quarks[i].quark;
193 * gst_event_type_get_flags:
194 * @type: a #GstEventType
196 * Gets the #GstEventTypeFlags associated with @type.
198 * Returns: a #GstEventTypeFlags.
201 gst_event_type_get_flags (GstEventType type)
203 GstEventTypeFlags ret;
205 ret = type & ((1 << GST_EVENT_NUM_SHIFT) - 1);
211 _gst_event_free (GstEvent * event)
215 g_return_if_fail (event != NULL);
216 g_return_if_fail (GST_IS_EVENT (event));
218 GST_CAT_LOG (GST_CAT_EVENT, "freeing event %p type %s", event,
219 GST_EVENT_TYPE_NAME (event));
221 s = GST_EVENT_STRUCTURE (event);
224 gst_structure_set_parent_refcount (s, NULL);
225 gst_structure_free (s);
228 g_slice_free1 (GST_MINI_OBJECT_SIZE (event), event);
231 static void gst_event_init (GstEventImpl * event, gsize size,
235 _gst_event_copy (GstEvent * event)
240 copy = g_slice_new0 (GstEventImpl);
242 gst_event_init (copy, sizeof (GstEventImpl), GST_EVENT_TYPE (event));
244 GST_EVENT_TIMESTAMP (copy) = GST_EVENT_TIMESTAMP (event);
245 GST_EVENT_SEQNUM (copy) = GST_EVENT_SEQNUM (event);
247 s = GST_EVENT_STRUCTURE (event);
249 GST_EVENT_STRUCTURE (copy) = gst_structure_copy (s);
250 gst_structure_set_parent_refcount (GST_EVENT_STRUCTURE (copy),
251 ©->event.mini_object.refcount);
253 return GST_EVENT_CAST (copy);
257 gst_event_init (GstEventImpl * event, gsize size, GstEventType type)
259 gst_mini_object_init (GST_MINI_OBJECT_CAST (event), _gst_event_type, size);
261 event->event.mini_object.copy = (GstMiniObjectCopyFunction) _gst_event_copy;
262 event->event.mini_object.free = (GstMiniObjectFreeFunction) _gst_event_free;
264 GST_EVENT_TYPE (event) = type;
265 GST_EVENT_TIMESTAMP (event) = GST_CLOCK_TIME_NONE;
266 GST_EVENT_SEQNUM (event) = gst_util_seqnum_next ();
270 gst_event_new (GstEventType type)
274 event = g_slice_new0 (GstEventImpl);
276 GST_CAT_DEBUG (GST_CAT_EVENT, "creating new event %p %s %d", event,
277 gst_event_type_get_name (type), type);
279 gst_event_init (event, sizeof (GstEventImpl), type);
281 return GST_EVENT_CAST (event);
285 * gst_event_new_custom:
286 * @type: The type of the new event
287 * @structure: (transfer full): the structure for the event. The event will
288 * take ownership of the structure.
290 * Create a new custom-typed event. This can be used for anything not
291 * handled by other event-specific functions to pass an event to another
294 * Make sure to allocate an event type with the #GST_EVENT_MAKE_TYPE macro,
295 * assigning a free number and filling in the correct direction and
296 * serialization flags.
298 * New custom events can also be created by subclassing the event type if
301 * Returns: (transfer full): the new custom event.
304 gst_event_new_custom (GstEventType type, GstStructure * structure)
308 /* structure must not have a parent */
309 event = gst_event_new (type);
311 if (!gst_structure_set_parent_refcount (structure,
312 &event->mini_object.refcount))
315 GST_EVENT_STRUCTURE (event) = structure;
322 gst_event_unref (event);
323 g_warning ("structure is already owned by another object");
329 * gst_event_get_structure:
330 * @event: The #GstEvent.
332 * Access the structure of the event.
334 * Returns: The structure of the event. The structure is still
335 * owned by the event, which means that you should not free it and
336 * that the pointer becomes invalid when you free the event.
341 gst_event_get_structure (GstEvent * event)
343 g_return_val_if_fail (GST_IS_EVENT (event), NULL);
345 return GST_EVENT_STRUCTURE (event);
349 * gst_event_writable_structure:
350 * @event: The #GstEvent.
352 * Get a writable version of the structure.
354 * Returns: The structure of the event. The structure is still
355 * owned by the event, which means that you should not free it and
356 * that the pointer becomes invalid when you free the event.
357 * This function checks if @event is writable and will never return NULL.
362 gst_event_writable_structure (GstEvent * event)
364 GstStructure *structure;
366 g_return_val_if_fail (GST_IS_EVENT (event), NULL);
367 g_return_val_if_fail (gst_event_is_writable (event), NULL);
369 structure = GST_EVENT_STRUCTURE (event);
371 if (structure == NULL) {
373 gst_structure_new_id_empty (gst_event_type_to_quark (GST_EVENT_TYPE
375 gst_structure_set_parent_refcount (structure, &event->mini_object.refcount);
376 GST_EVENT_STRUCTURE (event) = structure;
382 * gst_event_has_name:
383 * @event: The #GstEvent.
384 * @name: name to check
386 * Checks if @event has the given @name. This function is usually used to
387 * check the name of a custom event.
389 * Returns: %TRUE if @name matches the name of the event structure.
394 gst_event_has_name (GstEvent * event, const gchar * name)
396 g_return_val_if_fail (GST_IS_EVENT (event), FALSE);
398 if (GST_EVENT_STRUCTURE (event) == NULL)
401 return gst_structure_has_name (GST_EVENT_STRUCTURE (event), name);
405 * gst_event_get_seqnum:
406 * @event: A #GstEvent.
408 * Retrieve the sequence number of a event.
410 * Events have ever-incrementing sequence numbers, which may also be set
411 * explicitly via gst_event_set_seqnum(). Sequence numbers are typically used to
412 * indicate that a event corresponds to some other set of events or messages,
413 * for example an EOS event corresponding to a SEEK event. It is considered good
414 * practice to make this correspondence when possible, though it is not
417 * Note that events and messages share the same sequence number incrementor;
418 * two events or messages will never have the same sequence number unless
419 * that correspondence was made explicitly.
421 * Returns: The event's sequence number.
428 gst_event_get_seqnum (GstEvent * event)
430 g_return_val_if_fail (GST_IS_EVENT (event), -1);
432 return GST_EVENT_SEQNUM (event);
436 * gst_event_set_seqnum:
437 * @event: A #GstEvent.
438 * @seqnum: A sequence number.
440 * Set the sequence number of a event.
442 * This function might be called by the creator of a event to indicate that the
443 * event relates to other events or messages. See gst_event_get_seqnum() for
451 gst_event_set_seqnum (GstEvent * event, guint32 seqnum)
453 g_return_if_fail (GST_IS_EVENT (event));
455 GST_EVENT_SEQNUM (event) = seqnum;
458 /* FIXME 0.11: It would be nice to have flush events
459 * that don't reset the running time in the sinks
463 * gst_event_new_flush_start:
465 * Allocate a new flush start event. The flush start event can be sent
466 * upstream and downstream and travels out-of-bounds with the dataflow.
468 * It marks pads as being flushing and will make them return
469 * #GST_FLOW_WRONG_STATE when used for data flow with gst_pad_push(),
470 * gst_pad_chain(), gst_pad_alloc_buffer(), gst_pad_get_range() and
471 * gst_pad_pull_range(). Any event (except a #GST_EVENT_FLUSH_STOP) received
472 * on a flushing pad will return %FALSE immediately.
474 * Elements should unlock any blocking functions and exit their streaming
475 * functions as fast as possible when this event is received.
477 * This event is typically generated after a seek to flush out all queued data
478 * in the pipeline so that the new media is played as soon as possible.
480 * Returns: (transfer full): a new flush start event.
483 gst_event_new_flush_start (void)
485 return gst_event_new (GST_EVENT_FLUSH_START);
489 * gst_event_new_flush_stop:
490 * @reset_time: if time should be reset
492 * Allocate a new flush stop event. The flush stop event can be sent
493 * upstream and downstream and travels serialized with the dataflow.
494 * It is typically sent after sending a FLUSH_START event to make the
495 * pads accept data again.
497 * Elements can process this event synchronized with the dataflow since
498 * the preceeding FLUSH_START event stopped the dataflow.
500 * This event is typically generated to complete a seek and to resume
503 * Returns: (transfer full): a new flush stop event.
506 gst_event_new_flush_stop (gboolean reset_time)
510 GST_CAT_INFO (GST_CAT_EVENT, "creating flush stop %d", reset_time);
512 event = gst_event_new_custom (GST_EVENT_FLUSH_STOP,
513 gst_structure_new_id (GST_QUARK (EVENT_FLUSH_STOP),
514 GST_QUARK (RESET_TIME), G_TYPE_BOOLEAN, reset_time, NULL));
520 * gst_event_parse_flush_stop:
521 * @event: The event to parse
522 * @reset_time: (out): if time should be reset
524 * Parse the FLUSH_STOP event and retrieve the @reset_time member.
527 gst_event_parse_flush_stop (GstEvent * event, gboolean * reset_time)
529 GstStructure *structure;
531 g_return_if_fail (GST_IS_EVENT (event));
532 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_FLUSH_STOP);
534 structure = GST_EVENT_STRUCTURE (event);
535 if (G_LIKELY (reset_time))
537 g_value_get_boolean (gst_structure_id_get_value (structure,
538 GST_QUARK (RESET_TIME)));
544 * Create a new EOS event. The eos event can only travel downstream
545 * synchronized with the buffer flow. Elements that receive the EOS
546 * event on a pad can return #GST_FLOW_UNEXPECTED as a #GstFlowReturn
547 * when data after the EOS event arrives.
549 * The EOS event will travel down to the sink elements in the pipeline
550 * which will then post the #GST_MESSAGE_EOS on the bus after they have
551 * finished playing any buffered data.
553 * When all sinks have posted an EOS message, an EOS message is
554 * forwarded to the application.
556 * The EOS event itself will not cause any state transitions of the pipeline.
558 * Returns: (transfer full): the new EOS event.
561 gst_event_new_eos (void)
563 return gst_event_new (GST_EVENT_EOS);
567 * gst_event_new_caps:
568 * @caps: (transfer none): a #GstCaps
570 * Create a new CAPS event for @caps. The caps event can only travel downstream
571 * synchronized with the buffer flow and contains the format of the buffers
572 * that will follow after the event.
574 * Returns: (transfer full): the new CAPS event.
577 gst_event_new_caps (GstCaps * caps)
581 g_return_val_if_fail (caps != NULL, NULL);
582 g_return_val_if_fail (gst_caps_is_fixed (caps), NULL);
584 GST_CAT_INFO (GST_CAT_EVENT, "creating caps event %" GST_PTR_FORMAT, caps);
586 event = gst_event_new_custom (GST_EVENT_CAPS,
587 gst_structure_new_id (GST_QUARK (EVENT_CAPS),
588 GST_QUARK (CAPS), GST_TYPE_CAPS, caps, NULL));
594 * gst_event_parse_caps:
595 * @event: The event to parse
596 * @caps: (out): A pointer to the caps
598 * Get the caps from @event. The caps remains valid as long as @event remains
602 gst_event_parse_caps (GstEvent * event, GstCaps ** caps)
604 GstStructure *structure;
606 g_return_if_fail (GST_IS_EVENT (event));
607 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_CAPS);
609 structure = GST_EVENT_STRUCTURE (event);
612 g_value_get_boxed (gst_structure_id_get_value (structure,
617 * gst_event_new_segment:
618 * @segment: (transfer none): a #GstSegment
620 * Create a new SEGMENT event for @segment. The segment event can only travel
621 * downstream synchronized with the buffer flow and contains timing information
622 * and playback properties for the buffers that will follow.
624 * The newsegment event marks the range of buffers to be processed. All
625 * data not within the segment range is not to be processed. This can be
626 * used intelligently by plugins to apply more efficient methods of skipping
627 * unneeded data. The valid range is expressed with the @start and @stop
630 * The time value of the segment is used in conjunction with the start
631 * value to convert the buffer timestamps into the stream time. This is
632 * usually done in sinks to report the current stream_time.
633 * @time represents the stream_time of a buffer carrying a timestamp of
634 * @start. @time cannot be -1.
636 * @start cannot be -1, @stop can be -1. If there
637 * is a valid @stop given, it must be greater or equal the @start, including
638 * when the indicated playback @rate is < 0.
640 * The @applied_rate value provides information about any rate adjustment that
641 * has already been made to the timestamps and content on the buffers of the
642 * stream. (@rate * @applied_rate) should always equal the rate that has been
643 * requested for playback. For example, if an element has an input segment
644 * with intended playback @rate of 2.0 and applied_rate of 1.0, it can adjust
645 * incoming timestamps and buffer content by half and output a newsegment event
646 * with @rate of 1.0 and @applied_rate of 2.0
648 * After a newsegment event, the buffer stream time is calculated with:
650 * time + (TIMESTAMP(buf) - start) * ABS (rate * applied_rate)
652 * Returns: (transfer full): the new SEGMENT event.
655 gst_event_new_segment (const GstSegment * segment)
659 g_return_val_if_fail (segment != NULL, NULL);
660 g_return_val_if_fail (segment->rate != 0.0, NULL);
661 g_return_val_if_fail (segment->applied_rate != 0.0, NULL);
662 g_return_val_if_fail (segment->format != GST_FORMAT_UNDEFINED, NULL);
664 GST_CAT_INFO (GST_CAT_EVENT, "creating segment event %" GST_SEGMENT_FORMAT,
667 event = gst_event_new_custom (GST_EVENT_SEGMENT,
668 gst_structure_new_id (GST_QUARK (EVENT_SEGMENT),
669 GST_QUARK (SEGMENT), GST_TYPE_SEGMENT, segment, NULL));
675 * gst_event_parse_segment:
676 * @event: The event to parse
677 * @segment: (out) (transfer none): a pointer to a #GstSegment
679 * Parses a segment @event and stores the result in the given @segment location.
680 * @segment remains valid only until the @event is freed. Don't modify the segment
681 * and make a copy if you want to modify it or store it for later use.
684 gst_event_parse_segment (GstEvent * event, const GstSegment ** segment)
686 GstStructure *structure;
688 g_return_if_fail (GST_IS_EVENT (event));
689 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SEGMENT);
692 structure = GST_EVENT_STRUCTURE (event);
693 *segment = g_value_get_boxed (gst_structure_id_get_value (structure,
694 GST_QUARK (SEGMENT)));
699 * gst_event_copy_segment:
700 * @event: The event to parse
701 * @segment: a pointer to a #GstSegment
703 * Parses a segment @event and copies the #GstSegment into the location
707 gst_event_copy_segment (GstEvent * event, GstSegment * segment)
709 const GstSegment *src;
711 g_return_if_fail (GST_IS_EVENT (event));
712 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SEGMENT);
715 gst_event_parse_segment (event, &src);
716 gst_segment_copy_into (src, segment);
722 * @taglist: (transfer full): metadata list. The event will take ownership
725 * Generates a metadata tag event from the given @taglist.
727 * Returns: (transfer full): a new #GstEvent
730 gst_event_new_tag (GstTagList * taglist)
732 g_return_val_if_fail (taglist != NULL, NULL);
734 return gst_event_new_custom (GST_EVENT_TAG, (GstStructure *) taglist);
738 * gst_event_parse_tag:
739 * @event: a tag event
740 * @taglist: (out) (transfer none): pointer to metadata list
742 * Parses a tag @event and stores the results in the given @taglist location.
743 * No reference to the taglist will be returned, it remains valid only until
744 * the @event is freed. Don't modify or free the taglist, make a copy if you
745 * want to modify it or store it for later use.
748 gst_event_parse_tag (GstEvent * event, GstTagList ** taglist)
750 g_return_if_fail (GST_IS_EVENT (event));
751 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_TAG);
754 *taglist = (GstTagList *) GST_EVENT_STRUCTURE (event);
757 /* buffersize event */
759 * gst_event_new_buffer_size:
760 * @format: buffer format
761 * @minsize: minimum buffer size
762 * @maxsize: maximum buffer size
763 * @async: thread behavior
765 * Create a new buffersize event. The event is sent downstream and notifies
766 * elements that they should provide a buffer of the specified dimensions.
768 * When the @async flag is set, a thread boundary is preferred.
770 * Returns: (transfer full): a new #GstEvent
773 gst_event_new_buffer_size (GstFormat format, gint64 minsize,
774 gint64 maxsize, gboolean async)
777 GstStructure *structure;
779 GST_CAT_INFO (GST_CAT_EVENT,
780 "creating buffersize format %s, minsize %" G_GINT64_FORMAT
781 ", maxsize %" G_GINT64_FORMAT ", async %d", gst_format_get_name (format),
782 minsize, maxsize, async);
784 structure = gst_structure_new_id (GST_QUARK (EVENT_BUFFER_SIZE),
785 GST_QUARK (FORMAT), GST_TYPE_FORMAT, format,
786 GST_QUARK (MINSIZE), G_TYPE_INT64, minsize,
787 GST_QUARK (MAXSIZE), G_TYPE_INT64, maxsize,
788 GST_QUARK (ASYNC), G_TYPE_BOOLEAN, async, NULL);
789 event = gst_event_new_custom (GST_EVENT_BUFFERSIZE, structure);
795 * gst_event_parse_buffer_size:
796 * @event: The event to query
797 * @format: (out): A pointer to store the format in
798 * @minsize: (out): A pointer to store the minsize in
799 * @maxsize: (out): A pointer to store the maxsize in
800 * @async: (out): A pointer to store the async-flag in
802 * Get the format, minsize, maxsize and async-flag in the buffersize event.
805 gst_event_parse_buffer_size (GstEvent * event, GstFormat * format,
806 gint64 * minsize, gint64 * maxsize, gboolean * async)
808 const GstStructure *structure;
810 g_return_if_fail (GST_IS_EVENT (event));
811 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_BUFFERSIZE);
813 structure = GST_EVENT_STRUCTURE (event);
815 *format = (GstFormat)
816 g_value_get_enum (gst_structure_id_get_value (structure,
817 GST_QUARK (FORMAT)));
820 g_value_get_int64 (gst_structure_id_get_value (structure,
821 GST_QUARK (MINSIZE)));
824 g_value_get_int64 (gst_structure_id_get_value (structure,
825 GST_QUARK (MAXSIZE)));
828 g_value_get_boolean (gst_structure_id_get_value (structure,
834 * @type: the QoS type
835 * @proportion: the proportion of the qos message
836 * @diff: The time difference of the last Clock sync
837 * @timestamp: The timestamp of the buffer
839 * Allocate a new qos event with the given values.
840 * The QOS event is generated in an element that wants an upstream
841 * element to either reduce or increase its rate because of
842 * high/low CPU load or other resource usage such as network performance or
843 * throttling. Typically sinks generate these events for each buffer
846 * @type indicates the reason for the QoS event. #GST_QOS_TYPE_OVERFLOW is
847 * used when a buffer arrived in time or when the sink cannot keep up with
848 * the upstream datarate. #GST_QOS_TYPE_UNDERFLOW is when the sink is not
849 * receiving buffers fast enough and thus has to drop late buffers.
850 * #GST_QOS_TYPE_THROTTLE is used when the datarate is artificially limited
851 * by the application, for example to reduce power consumption.
853 * @proportion indicates the real-time performance of the streaming in the
854 * element that generated the QoS event (usually the sink). The value is
855 * generally computed based on more long term statistics about the streams
856 * timestamps compared to the clock.
857 * A value < 1.0 indicates that the upstream element is producing data faster
858 * than real-time. A value > 1.0 indicates that the upstream element is not
859 * producing data fast enough. 1.0 is the ideal @proportion value. The
860 * proportion value can safely be used to lower or increase the quality of
863 * @diff is the difference against the clock in running time of the last
864 * buffer that caused the element to generate the QOS event. A negative value
865 * means that the buffer with @timestamp arrived in time. A positive value
866 * indicates how late the buffer with @timestamp was. When throttling is
867 * enabled, @diff will be set to the requested throttling interval.
869 * @timestamp is the timestamp of the last buffer that cause the element
870 * to generate the QOS event. It is expressed in running time and thus an ever
873 * The upstream element can use the @diff and @timestamp values to decide
874 * whether to process more buffers. For possitive @diff, all buffers with
875 * timestamp <= @timestamp + @diff will certainly arrive late in the sink
876 * as well. A (negative) @diff value so that @timestamp + @diff would yield a
877 * result smaller than 0 is not allowed.
879 * The application can use general event probes to intercept the QoS
880 * event and implement custom application specific QoS handling.
882 * Returns: (transfer full): a new QOS event.
885 gst_event_new_qos (GstQOSType type, gdouble proportion,
886 GstClockTimeDiff diff, GstClockTime timestamp)
889 GstStructure *structure;
891 /* diff must be positive or timestamp + diff must be positive */
892 g_return_val_if_fail (diff >= 0 || -diff <= timestamp, NULL);
894 GST_CAT_LOG (GST_CAT_EVENT,
895 "creating qos type %d, proportion %lf, diff %" G_GINT64_FORMAT
896 ", timestamp %" GST_TIME_FORMAT, type, proportion,
897 diff, GST_TIME_ARGS (timestamp));
899 structure = gst_structure_new_id (GST_QUARK (EVENT_QOS),
900 GST_QUARK (TYPE), GST_TYPE_QOS_TYPE, type,
901 GST_QUARK (PROPORTION), G_TYPE_DOUBLE, proportion,
902 GST_QUARK (DIFF), G_TYPE_INT64, diff,
903 GST_QUARK (TIMESTAMP), G_TYPE_UINT64, timestamp, NULL);
904 event = gst_event_new_custom (GST_EVENT_QOS, structure);
910 * gst_event_parse_qos:
911 * @event: The event to query
912 * @type: (out): A pointer to store the QoS type in
913 * @proportion: (out): A pointer to store the proportion in
914 * @diff: (out): A pointer to store the diff in
915 * @timestamp: (out): A pointer to store the timestamp in
917 * Get the type, proportion, diff and timestamp in the qos event. See
918 * gst_event_new_qos() for more information about the different QoS values.
921 gst_event_parse_qos (GstEvent * event, GstQOSType * type,
922 gdouble * proportion, GstClockTimeDiff * diff, GstClockTime * timestamp)
924 const GstStructure *structure;
926 g_return_if_fail (GST_IS_EVENT (event));
927 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_QOS);
929 structure = GST_EVENT_STRUCTURE (event);
932 g_value_get_enum (gst_structure_id_get_value (structure,
936 g_value_get_double (gst_structure_id_get_value (structure,
937 GST_QUARK (PROPORTION)));
940 g_value_get_int64 (gst_structure_id_get_value (structure,
944 g_value_get_uint64 (gst_structure_id_get_value (structure,
945 GST_QUARK (TIMESTAMP)));
949 * gst_event_new_seek:
950 * @rate: The new playback rate
951 * @format: The format of the seek values
952 * @flags: The optional seek flags
953 * @start_type: The type and flags for the new start position
954 * @start: The value of the new start position
955 * @stop_type: The type and flags for the new stop position
956 * @stop: The value of the new stop position
958 * Allocate a new seek event with the given parameters.
960 * The seek event configures playback of the pipeline between @start to @stop
961 * at the speed given in @rate, also called a playback segment.
962 * The @start and @stop values are expressed in @format.
964 * A @rate of 1.0 means normal playback rate, 2.0 means double speed.
965 * Negatives values means backwards playback. A value of 0.0 for the
966 * rate is not allowed and should be accomplished instead by PAUSING the
969 * A pipeline has a default playback segment configured with a start
970 * position of 0, a stop position of -1 and a rate of 1.0. The currently
971 * configured playback segment can be queried with #GST_QUERY_SEGMENT.
973 * @start_type and @stop_type specify how to adjust the currently configured
974 * start and stop fields in playback segment. Adjustments can be made relative
975 * or absolute to the last configured values. A type of #GST_SEEK_TYPE_NONE
976 * means that the position should not be updated.
978 * When the rate is positive and @start has been updated, playback will start
979 * from the newly configured start position.
981 * For negative rates, playback will start from the newly configured stop
982 * position (if any). If the stop position if updated, it must be different from
983 * -1 for negative rates.
985 * It is not possible to seek relative to the current playback position, to do
986 * this, PAUSE the pipeline, query the current playback position with
987 * #GST_QUERY_POSITION and update the playback segment current position with a
988 * #GST_SEEK_TYPE_SET to the desired position.
990 * Returns: (transfer full): a new seek event.
993 gst_event_new_seek (gdouble rate, GstFormat format, GstSeekFlags flags,
994 GstSeekType start_type, gint64 start, GstSeekType stop_type, gint64 stop)
997 GstStructure *structure;
999 g_return_val_if_fail (rate != 0.0, NULL);
1001 if (format == GST_FORMAT_TIME) {
1002 GST_CAT_INFO (GST_CAT_EVENT,
1003 "creating seek rate %lf, format TIME, flags %d, "
1004 "start_type %d, start %" GST_TIME_FORMAT ", "
1005 "stop_type %d, stop %" GST_TIME_FORMAT,
1006 rate, flags, start_type, GST_TIME_ARGS (start),
1007 stop_type, GST_TIME_ARGS (stop));
1009 GST_CAT_INFO (GST_CAT_EVENT,
1010 "creating seek rate %lf, format %s, flags %d, "
1011 "start_type %d, start %" G_GINT64_FORMAT ", "
1012 "stop_type %d, stop %" G_GINT64_FORMAT,
1013 rate, gst_format_get_name (format), flags, start_type, start, stop_type,
1017 structure = gst_structure_new_id (GST_QUARK (EVENT_SEEK),
1018 GST_QUARK (RATE), G_TYPE_DOUBLE, rate,
1019 GST_QUARK (FORMAT), GST_TYPE_FORMAT, format,
1020 GST_QUARK (FLAGS), GST_TYPE_SEEK_FLAGS, flags,
1021 GST_QUARK (CUR_TYPE), GST_TYPE_SEEK_TYPE, start_type,
1022 GST_QUARK (CUR), G_TYPE_INT64, start,
1023 GST_QUARK (STOP_TYPE), GST_TYPE_SEEK_TYPE, stop_type,
1024 GST_QUARK (STOP), G_TYPE_INT64, stop, NULL);
1025 event = gst_event_new_custom (GST_EVENT_SEEK, structure);
1031 * gst_event_parse_seek:
1032 * @event: a seek event
1033 * @rate: (out): result location for the rate
1034 * @format: (out): result location for the stream format
1035 * @flags: (out): result location for the #GstSeekFlags
1036 * @start_type: (out): result location for the #GstSeekType of the start position
1037 * @start: (out): result location for the start postion expressed in @format
1038 * @stop_type: (out): result location for the #GstSeekType of the stop position
1039 * @stop: (out): result location for the stop postion expressed in @format
1041 * Parses a seek @event and stores the results in the given result locations.
1044 gst_event_parse_seek (GstEvent * event, gdouble * rate,
1045 GstFormat * format, GstSeekFlags * flags, GstSeekType * start_type,
1046 gint64 * start, GstSeekType * stop_type, gint64 * stop)
1048 const GstStructure *structure;
1050 g_return_if_fail (GST_IS_EVENT (event));
1051 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SEEK);
1053 structure = GST_EVENT_STRUCTURE (event);
1056 g_value_get_double (gst_structure_id_get_value (structure,
1059 *format = (GstFormat)
1060 g_value_get_enum (gst_structure_id_get_value (structure,
1061 GST_QUARK (FORMAT)));
1063 *flags = (GstSeekFlags)
1064 g_value_get_flags (gst_structure_id_get_value (structure,
1065 GST_QUARK (FLAGS)));
1067 *start_type = (GstSeekType)
1068 g_value_get_enum (gst_structure_id_get_value (structure,
1069 GST_QUARK (CUR_TYPE)));
1072 g_value_get_int64 (gst_structure_id_get_value (structure,
1075 *stop_type = (GstSeekType)
1076 g_value_get_enum (gst_structure_id_get_value (structure,
1077 GST_QUARK (STOP_TYPE)));
1080 g_value_get_int64 (gst_structure_id_get_value (structure,
1085 * gst_event_new_navigation:
1086 * @structure: (transfer full): description of the event. The event will take
1087 * ownership of the structure.
1089 * Create a new navigation event from the given description.
1091 * Returns: (transfer full): a new #GstEvent
1094 gst_event_new_navigation (GstStructure * structure)
1096 g_return_val_if_fail (structure != NULL, NULL);
1098 return gst_event_new_custom (GST_EVENT_NAVIGATION, structure);
1102 * gst_event_new_latency:
1103 * @latency: the new latency value
1105 * Create a new latency event. The event is sent upstream from the sinks and
1106 * notifies elements that they should add an additional @latency to the
1107 * running time before synchronising against the clock.
1109 * The latency is mostly used in live sinks and is always expressed in
1112 * Returns: (transfer full): a new #GstEvent
1117 gst_event_new_latency (GstClockTime latency)
1120 GstStructure *structure;
1122 GST_CAT_INFO (GST_CAT_EVENT,
1123 "creating latency event %" GST_TIME_FORMAT, GST_TIME_ARGS (latency));
1125 structure = gst_structure_new_id (GST_QUARK (EVENT_LATENCY),
1126 GST_QUARK (LATENCY), G_TYPE_UINT64, latency, NULL);
1127 event = gst_event_new_custom (GST_EVENT_LATENCY, structure);
1133 * gst_event_parse_latency:
1134 * @event: The event to query
1135 * @latency: (out): A pointer to store the latency in.
1137 * Get the latency in the latency event.
1142 gst_event_parse_latency (GstEvent * event, GstClockTime * latency)
1144 g_return_if_fail (GST_IS_EVENT (event));
1145 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_LATENCY);
1149 g_value_get_uint64 (gst_structure_id_get_value (GST_EVENT_STRUCTURE
1150 (event), GST_QUARK (LATENCY)));
1154 * gst_event_new_step:
1155 * @format: the format of @amount
1156 * @amount: the amount of data to step
1157 * @rate: the step rate
1158 * @flush: flushing steps
1159 * @intermediate: intermediate steps
1161 * Create a new step event. The purpose of the step event is to instruct a sink
1162 * to skip @amount (expressed in @format) of media. It can be used to implement
1163 * stepping through the video frame by frame or for doing fast trick modes.
1165 * A rate of <= 0.0 is not allowed. Pause the pipeline, for the effect of rate
1166 * = 0.0 or first reverse the direction of playback using a seek event to get
1167 * the same effect as rate < 0.0.
1169 * The @flush flag will clear any pending data in the pipeline before starting
1170 * the step operation.
1172 * The @intermediate flag instructs the pipeline that this step operation is
1173 * part of a larger step operation.
1175 * Returns: (transfer full): a new #GstEvent
1180 gst_event_new_step (GstFormat format, guint64 amount, gdouble rate,
1181 gboolean flush, gboolean intermediate)
1184 GstStructure *structure;
1186 g_return_val_if_fail (rate > 0.0, NULL);
1188 GST_CAT_INFO (GST_CAT_EVENT, "creating step event");
1190 structure = gst_structure_new_id (GST_QUARK (EVENT_STEP),
1191 GST_QUARK (FORMAT), GST_TYPE_FORMAT, format,
1192 GST_QUARK (AMOUNT), G_TYPE_UINT64, amount,
1193 GST_QUARK (RATE), G_TYPE_DOUBLE, rate,
1194 GST_QUARK (FLUSH), G_TYPE_BOOLEAN, flush,
1195 GST_QUARK (INTERMEDIATE), G_TYPE_BOOLEAN, intermediate, NULL);
1196 event = gst_event_new_custom (GST_EVENT_STEP, structure);
1202 * gst_event_parse_step:
1203 * @event: The event to query
1204 * @format: (out) (allow-none): a pointer to store the format in
1205 * @amount: (out) (allow-none): a pointer to store the amount in
1206 * @rate: (out) (allow-none): a pointer to store the rate in
1207 * @flush: (out) (allow-none): a pointer to store the flush boolean in
1208 * @intermediate: (out) (allow-none): a pointer to store the intermediate
1211 * Parse the step event.
1216 gst_event_parse_step (GstEvent * event, GstFormat * format, guint64 * amount,
1217 gdouble * rate, gboolean * flush, gboolean * intermediate)
1219 const GstStructure *structure;
1221 g_return_if_fail (GST_IS_EVENT (event));
1222 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_STEP);
1224 structure = GST_EVENT_STRUCTURE (event);
1227 (GstFormat) g_value_get_enum (gst_structure_id_get_value (structure,
1228 GST_QUARK (FORMAT)));
1230 *amount = g_value_get_uint64 (gst_structure_id_get_value (structure,
1231 GST_QUARK (AMOUNT)));
1233 *rate = g_value_get_double (gst_structure_id_get_value (structure,
1236 *flush = g_value_get_boolean (gst_structure_id_get_value (structure,
1237 GST_QUARK (FLUSH)));
1239 *intermediate = g_value_get_boolean (gst_structure_id_get_value (structure,
1240 GST_QUARK (INTERMEDIATE)));
1244 * gst_event_new_reconfigure:
1246 * Create a new reconfigure event. The purpose of the reconfingure event is
1247 * to travel upstream and make elements renegotiate their caps or reconfigure
1248 * their buffer pools. This is useful when changing properties on elements
1249 * or changing the topology of the pipeline.
1251 * Returns: (transfer full): a new #GstEvent
1256 gst_event_new_reconfigure (void)
1260 GST_CAT_INFO (GST_CAT_EVENT, "creating reconfigure event");
1262 event = gst_event_new_custom (GST_EVENT_RECONFIGURE, NULL);
1268 * gst_event_new_sink_message:
1269 * @msg: (transfer none): the #GstMessage to be posted
1271 * Create a new sink-message event. The purpose of the sink-message event is
1272 * to instruct a sink to post the message contained in the event synchronized
1275 * Returns: (transfer full): a new #GstEvent
1279 /* FIXME 0.11: take ownership of msg for consistency? */
1281 gst_event_new_sink_message (GstMessage * msg)
1284 GstStructure *structure;
1286 g_return_val_if_fail (msg != NULL, NULL);
1288 GST_CAT_INFO (GST_CAT_EVENT, "creating sink-message event");
1290 structure = gst_structure_new_id (GST_QUARK (EVENT_SINK_MESSAGE),
1291 GST_QUARK (MESSAGE), GST_TYPE_MESSAGE, msg, NULL);
1292 event = gst_event_new_custom (GST_EVENT_SINK_MESSAGE, structure);
1298 * gst_event_parse_sink_message:
1299 * @event: The event to query
1300 * @msg: (out) (transfer full): a pointer to store the #GstMessage in.
1302 * Parse the sink-message event. Unref @msg after usage.
1307 gst_event_parse_sink_message (GstEvent * event, GstMessage ** msg)
1309 const GstStructure *structure;
1311 g_return_if_fail (GST_IS_EVENT (event));
1312 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SINK_MESSAGE);
1314 structure = GST_EVENT_STRUCTURE (event);
1317 GST_MESSAGE (g_value_dup_boxed (gst_structure_id_get_value
1318 (structure, GST_QUARK (MESSAGE))));
1322 * gst_event_new_stream_start
1324 * Create a new STREAM_START event. The stream start event can only
1325 * travel downstream synchronized with the buffer flow. It is expected
1326 * to be the first event that is sent for a new stream.
1328 * Source elements, demuxers and other elements that create new streams
1329 * are supposed to send this event as the first event of a new stream. It
1330 * should not be send after a flushing seek or in similar situations
1331 * and is used to mark the beginning of a new logical stream. Elements
1332 * combining multiple streams must ensure that this event is only forwarded
1333 * downstream once and not for every single input stream.
1335 * Returns: (transfer full): the new STREAM_START event.
1338 gst_event_new_stream_start (void)
1340 return gst_event_new (GST_EVENT_STREAM_START);