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 specity 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 static GType _gst_event_type = 0;
97 static GstEventQuarks event_quarks[] = {
98 {GST_EVENT_UNKNOWN, "unknown", 0},
99 {GST_EVENT_FLUSH_START, "flush-start", 0},
100 {GST_EVENT_FLUSH_STOP, "flush-stop", 0},
101 {GST_EVENT_EOS, "eos", 0},
102 {GST_EVENT_CAPS, "caps", 0},
103 {GST_EVENT_NEWSEGMENT, "newsegment", 0},
104 {GST_EVENT_TAG, "tag", 0},
105 {GST_EVENT_BUFFERSIZE, "buffersize", 0},
106 {GST_EVENT_SINK_MESSAGE, "sink-message", 0},
107 {GST_EVENT_QOS, "qos", 0},
108 {GST_EVENT_SEEK, "seek", 0},
109 {GST_EVENT_NAVIGATION, "navigation", 0},
110 {GST_EVENT_LATENCY, "latency", 0},
111 {GST_EVENT_STEP, "step", 0},
112 {GST_EVENT_RECONFIGURE, "reconfigure", 0},
113 {GST_EVENT_CUSTOM_UPSTREAM, "custom-upstream", 0},
114 {GST_EVENT_CUSTOM_DOWNSTREAM, "custom-downstream", 0},
115 {GST_EVENT_CUSTOM_DOWNSTREAM_OOB, "custom-downstream-oob", 0},
116 {GST_EVENT_CUSTOM_BOTH, "custom-both", 0},
117 {GST_EVENT_CUSTOM_BOTH_OOB, "custom-both-oob", 0},
123 _gst_event_initialize (void)
127 gst_event_get_type ();
128 g_type_class_ref (gst_seek_flags_get_type ());
129 g_type_class_ref (gst_seek_type_get_type ());
131 for (i = 0; event_quarks[i].name; i++) {
132 event_quarks[i].quark = g_quark_from_static_string (event_quarks[i].name);
137 * gst_event_type_get_name:
138 * @type: the event type
140 * Get a printable name for the given event type. Do not modify or free.
142 * Returns: a reference to the static name of the event.
145 gst_event_type_get_name (GstEventType type)
149 for (i = 0; event_quarks[i].name; i++) {
150 if (type == event_quarks[i].type)
151 return event_quarks[i].name;
157 * gst_event_type_to_quark:
158 * @type: the event type
160 * Get the unique quark for the given event type.
162 * Returns: the quark associated with the event type
165 gst_event_type_to_quark (GstEventType type)
169 for (i = 0; event_quarks[i].name; i++) {
170 if (type == event_quarks[i].type)
171 return event_quarks[i].quark;
177 * gst_event_type_get_flags:
178 * @type: a #GstEventType
180 * Gets the #GstEventTypeFlags associated with @type.
182 * Returns: a #GstEventTypeFlags.
185 gst_event_type_get_flags (GstEventType type)
187 GstEventTypeFlags ret;
189 ret = type & ((1 << GST_EVENT_STICKY_SHIFT) - 1);
195 gst_event_get_type (void)
197 if (G_UNLIKELY (_gst_event_type == 0)) {
198 _gst_event_type = gst_mini_object_register ("GstEvent");
200 return _gst_event_type;
204 _gst_event_free (GstEvent * event)
206 g_return_if_fail (event != NULL);
207 g_return_if_fail (GST_IS_EVENT (event));
209 GST_CAT_LOG (GST_CAT_EVENT, "freeing event %p type %s", event,
210 GST_EVENT_TYPE_NAME (event));
212 if (event->structure) {
213 gst_structure_set_parent_refcount (event->structure, NULL);
214 gst_structure_free (event->structure);
217 g_slice_free1 (GST_MINI_OBJECT_SIZE (event), event);
220 static void gst_event_init (GstEvent * event, gsize size, GstEventType type);
223 _gst_event_copy (GstEvent * event)
227 copy = g_slice_new0 (GstEvent);
229 gst_event_init (copy, sizeof (GstEvent), GST_EVENT_TYPE (event));
231 GST_EVENT_TIMESTAMP (copy) = GST_EVENT_TIMESTAMP (event);
232 GST_EVENT_SEQNUM (copy) = GST_EVENT_SEQNUM (event);
234 if (event->structure) {
235 copy->structure = gst_structure_copy (event->structure);
236 gst_structure_set_parent_refcount (copy->structure,
237 ©->mini_object.refcount);
243 gst_event_init (GstEvent * event, gsize size, GstEventType type)
245 gst_mini_object_init (GST_MINI_OBJECT_CAST (event), _gst_event_type, size);
247 event->mini_object.copy = (GstMiniObjectCopyFunction) _gst_event_copy;
248 event->mini_object.free = (GstMiniObjectFreeFunction) _gst_event_free;
250 GST_EVENT_TYPE (event) = type;
251 GST_EVENT_TIMESTAMP (event) = GST_CLOCK_TIME_NONE;
252 GST_EVENT_SEQNUM (event) = gst_util_seqnum_next ();
256 gst_event_new (GstEventType type)
260 event = g_slice_new0 (GstEvent);
262 GST_CAT_DEBUG (GST_CAT_EVENT, "creating new event %p %s %d", event,
263 gst_event_type_get_name (type), type);
265 gst_event_init (event, sizeof (GstEvent), type);
271 * gst_event_new_custom:
272 * @type: The type of the new event
273 * @structure: (transfer full): the structure for the event. The event will
274 * take ownership of the structure.
276 * Create a new custom-typed event. This can be used for anything not
277 * handled by other event-specific functions to pass an event to another
280 * Make sure to allocate an event type with the #GST_EVENT_MAKE_TYPE macro,
281 * assigning a free number and filling in the correct direction and
282 * serialization flags.
284 * New custom events can also be created by subclassing the event type if
287 * Returns: (transfer full): the new custom event.
290 gst_event_new_custom (GstEventType type, GstStructure * structure)
294 /* structure must not have a parent */
296 g_return_val_if_fail (structure->parent_refcount == NULL, NULL);
298 event = gst_event_new (type);
300 gst_structure_set_parent_refcount (structure, &event->mini_object.refcount);
301 event->structure = structure;
307 * gst_event_get_structure:
308 * @event: The #GstEvent.
310 * Access the structure of the event.
312 * Returns: The structure of the event. The structure is still
313 * owned by the event, which means that you should not free it and
314 * that the pointer becomes invalid when you free the event.
319 gst_event_get_structure (GstEvent * event)
321 g_return_val_if_fail (GST_IS_EVENT (event), NULL);
323 return event->structure;
327 * gst_event_has_name:
328 * @event: The #GstEvent.
329 * @name: name to check
331 * Checks if @event has the given @name. This function is usually used to
332 * check the name of a custom event.
334 * Returns: %TRUE if @name matches the name of the event structure.
339 gst_event_has_name (GstEvent * event, const gchar * name)
341 g_return_val_if_fail (GST_IS_EVENT (event), FALSE);
343 if (event->structure == NULL)
346 return gst_structure_has_name (event->structure, name);
350 * gst_event_get_seqnum:
351 * @event: A #GstEvent.
353 * Retrieve the sequence number of a event.
355 * Events have ever-incrementing sequence numbers, which may also be set
356 * explicitly via gst_event_set_seqnum(). Sequence numbers are typically used to
357 * indicate that a event corresponds to some other set of events or messages,
358 * for example an EOS event corresponding to a SEEK event. It is considered good
359 * practice to make this correspondence when possible, though it is not
362 * Note that events and messages share the same sequence number incrementor;
363 * two events or messages will never not have the same sequence number unless
364 * that correspondence was made explicitly.
366 * Returns: The event's sequence number.
373 gst_event_get_seqnum (GstEvent * event)
375 g_return_val_if_fail (GST_IS_EVENT (event), -1);
377 return GST_EVENT_SEQNUM (event);
381 * gst_event_set_seqnum:
382 * @event: A #GstEvent.
383 * @seqnum: A sequence number.
385 * Set the sequence number of a event.
387 * This function might be called by the creator of a event to indicate that the
388 * event relates to other events or messages. See gst_event_get_seqnum() for
396 gst_event_set_seqnum (GstEvent * event, guint32 seqnum)
398 g_return_if_fail (GST_IS_EVENT (event));
400 GST_EVENT_SEQNUM (event) = seqnum;
403 /* FIXME 0.11: It would be nice to have flush events
404 * that don't reset the running time in the sinks
408 * gst_event_new_flush_start:
410 * Allocate a new flush start event. The flush start event can be sent
411 * upstream and downstream and travels out-of-bounds with the dataflow.
413 * It marks pads as being flushing and will make them return
414 * #GST_FLOW_WRONG_STATE when used for data flow with gst_pad_push(),
415 * gst_pad_chain(), gst_pad_alloc_buffer(), gst_pad_get_range() and
416 * gst_pad_pull_range(). Any event (except a #GST_EVENT_FLUSH_STOP) received
417 * on a flushing pad will return %FALSE immediately.
419 * Elements should unlock any blocking functions and exit their streaming
420 * functions as fast as possible when this event is received.
422 * This event is typically generated after a seek to flush out all queued data
423 * in the pipeline so that the new media is played as soon as possible.
425 * Returns: (transfer full): a new flush start event.
428 gst_event_new_flush_start (void)
430 return gst_event_new (GST_EVENT_FLUSH_START);
434 * gst_event_new_flush_stop:
436 * Allocate a new flush stop event. The flush stop event can be sent
437 * upstream and downstream and travels serialized with the dataflow.
438 * It is typically sent after sending a FLUSH_START event to make the
439 * pads accept data again.
441 * Elements can process this event synchronized with the dataflow since
442 * the preceeding FLUSH_START event stopped the dataflow.
444 * This event is typically generated to complete a seek and to resume
447 * Returns: (transfer full): a new flush stop event.
450 gst_event_new_flush_stop (void)
452 return gst_event_new (GST_EVENT_FLUSH_STOP);
458 * Create a new EOS event. The eos event can only travel downstream
459 * synchronized with the buffer flow. Elements that receive the EOS
460 * event on a pad can return #GST_FLOW_UNEXPECTED as a #GstFlowReturn
461 * when data after the EOS event arrives.
463 * The EOS event will travel down to the sink elements in the pipeline
464 * which will then post the #GST_MESSAGE_EOS on the bus after they have
465 * finished playing any buffered data.
467 * When all sinks have posted an EOS message, an EOS message is
468 * forwarded to the application.
470 * The EOS event itself will not cause any state transitions of the pipeline.
472 * Returns: (transfer full): the new EOS event.
475 gst_event_new_eos (void)
477 return gst_event_new (GST_EVENT_EOS);
481 * gst_event_new_caps:
484 * Create a new CAPS event for @caps. The caps event can only travel downstream
485 * synchronized with the buffer flow and contain the format of the buffers
486 * that will follow after the event.
488 * Returns: (transfer full): the new CAPS event.
491 gst_event_new_caps (GstCaps * caps)
495 g_return_val_if_fail (caps != NULL && gst_caps_is_fixed (caps), NULL);
497 GST_CAT_INFO (GST_CAT_EVENT, "creating caps event %" GST_PTR_FORMAT, caps);
499 event = gst_event_new_custom (GST_EVENT_CAPS,
500 gst_structure_id_new (GST_QUARK (EVENT_CAPS),
501 GST_QUARK (CAPS), GST_TYPE_CAPS, caps, NULL));
507 * gst_event_parse_caps:
508 * @event: The event to parse
509 * @caps: (out): A pointer to the caps
511 * Get the caps from @event. The caps remains valid as long as @event remains
515 gst_event_parse_caps (GstEvent * event, GstCaps ** caps)
517 GstStructure *structure;
519 g_return_if_fail (GST_IS_EVENT (event));
520 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_CAPS);
522 structure = event->structure;
525 g_value_get_boxed (gst_structure_id_get_value (structure,
530 * gst_event_new_new_segment:
531 * @update: Whether this segment is an update to a previous one
532 * @rate: A new rate for playback
533 * @applied_rate: The rate factor which has already been applied
534 * @format: The format of the segment values
535 * @start: The start value of the segment
536 * @stop: The stop value of the segment
537 * @time: the time value of the segment
539 * Allocate a new newsegment event with the given format/values triplets.
541 * The newsegment event marks the range of buffers to be processed. All
542 * data not within the segment range is not to be processed. This can be
543 * used intelligently by plugins to apply more efficient methods of skipping
544 * unneeded data. The valid range is expressed with the @start and @stop
547 * The time value of the segment is used in conjunction with the start
548 * value to convert the buffer timestamps into the stream time. This is
549 * usually done in sinks to report the current stream_time.
550 * @time represents the stream_time of a buffer carrying a timestamp of
551 * @start. @time cannot be -1.
553 * @start cannot be -1, @stop can be -1. If there
554 * is a valid @stop given, it must be greater or equal the @start, including
555 * when the indicated playback @rate is < 0.
557 * The @applied_rate value provides information about any rate adjustment that
558 * has already been made to the timestamps and content on the buffers of the
559 * stream. (@rate * @applied_rate) should always equal the rate that has been
560 * requested for playback. For example, if an element has an input segment
561 * with intended playback @rate of 2.0 and applied_rate of 1.0, it can adjust
562 * incoming timestamps and buffer content by half and output a newsegment event
563 * with @rate of 1.0 and @applied_rate of 2.0
565 * After a newsegment event, the buffer stream time is calculated with:
567 * time + (TIMESTAMP(buf) - start) * ABS (rate * applied_rate)
569 * Returns: (transfer full): a new newsegment event.
574 gst_event_new_new_segment (gboolean update, gdouble rate,
575 gdouble applied_rate, GstFormat format, gint64 start, gint64 stop,
579 GstStructure *structure;
581 g_return_val_if_fail (rate != 0.0, NULL);
582 g_return_val_if_fail (applied_rate != 0.0, NULL);
584 if (format == GST_FORMAT_TIME) {
585 GST_CAT_INFO (GST_CAT_EVENT,
586 "creating newsegment update %d, rate %lf, format GST_FORMAT_TIME, "
587 "start %" GST_TIME_FORMAT ", stop %" GST_TIME_FORMAT
588 ", time %" GST_TIME_FORMAT,
589 update, rate, GST_TIME_ARGS (start),
590 GST_TIME_ARGS (stop), GST_TIME_ARGS (time));
592 GST_CAT_INFO (GST_CAT_EVENT,
593 "creating newsegment update %d, rate %lf, format %s, "
594 "start %" G_GINT64_FORMAT ", stop %" G_GINT64_FORMAT ", time %"
595 G_GINT64_FORMAT, update, rate, gst_format_get_name (format), start,
599 g_return_val_if_fail (time != -1, NULL);
600 g_return_val_if_fail (start != -1, NULL);
602 g_return_val_if_fail (start <= stop, NULL);
604 structure = gst_structure_id_new (GST_QUARK (EVENT_NEWSEGMENT),
605 GST_QUARK (UPDATE), G_TYPE_BOOLEAN, update,
606 GST_QUARK (RATE), G_TYPE_DOUBLE, rate,
607 GST_QUARK (APPLIED_RATE), G_TYPE_DOUBLE, applied_rate,
608 GST_QUARK (FORMAT), GST_TYPE_FORMAT, format,
609 GST_QUARK (START), G_TYPE_INT64, start,
610 GST_QUARK (STOP), G_TYPE_INT64, stop,
611 GST_QUARK (TIME), G_TYPE_INT64, time, NULL);
612 event = gst_event_new_custom (GST_EVENT_NEWSEGMENT, structure);
618 * gst_event_parse_new_segment:
619 * @event: The event to query
620 * @update: (out): A pointer to the update flag of the segment
621 * @rate: (out): A pointer to the rate of the segment
622 * @applied_rate: (out): A pointer to the applied_rate of the segment
623 * @format: (out): A pointer to the format of the newsegment values
624 * @start: (out): A pointer to store the start value in
625 * @stop: (out): A pointer to store the stop value in
626 * @time: (out): A pointer to store the time value in
628 * Get the update, rate, applied_rate, format, start, stop and
629 * time in the newsegment event. See gst_event_new_new_segment()
630 * for a full description of the newsegment event.
635 gst_event_parse_new_segment (GstEvent * event, gboolean * update,
636 gdouble * rate, gdouble * applied_rate, GstFormat * format,
637 gint64 * start, gint64 * stop, gint64 * time)
639 const GstStructure *structure;
641 g_return_if_fail (GST_IS_EVENT (event));
642 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_NEWSEGMENT);
644 structure = event->structure;
645 if (G_LIKELY (update))
647 g_value_get_boolean (gst_structure_id_get_value (structure,
648 GST_QUARK (UPDATE)));
651 g_value_get_double (gst_structure_id_get_value (structure,
653 if (G_LIKELY (applied_rate))
655 g_value_get_double (gst_structure_id_get_value (structure,
656 GST_QUARK (APPLIED_RATE)));
657 if (G_LIKELY (format))
659 g_value_get_enum (gst_structure_id_get_value (structure,
660 GST_QUARK (FORMAT)));
661 if (G_LIKELY (start))
663 g_value_get_int64 (gst_structure_id_get_value (structure,
667 g_value_get_int64 (gst_structure_id_get_value (structure,
671 g_value_get_int64 (gst_structure_id_get_value (structure,
677 * @taglist: (transfer full): metadata list. The event will take ownership
680 * Generates a metadata tag event from the given @taglist.
682 * Returns: (transfer full): a new #GstEvent
685 gst_event_new_tag (GstTagList * taglist)
687 g_return_val_if_fail (taglist != NULL, NULL);
689 return gst_event_new_custom (GST_EVENT_TAG, (GstStructure *) taglist);
693 * gst_event_parse_tag:
694 * @event: a tag event
695 * @taglist: (out) (transfer none): pointer to metadata list
697 * Parses a tag @event and stores the results in the given @taglist location.
698 * No reference to the taglist will be returned, it remains valid only until
699 * the @event is freed. Don't modify or free the taglist, make a copy if you
700 * want to modify it or store it for later use.
703 gst_event_parse_tag (GstEvent * event, GstTagList ** taglist)
705 g_return_if_fail (GST_IS_EVENT (event));
706 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_TAG);
709 *taglist = (GstTagList *) event->structure;
712 /* buffersize event */
714 * gst_event_new_buffer_size:
715 * @format: buffer format
716 * @minsize: minimum buffer size
717 * @maxsize: maximum buffer size
718 * @async: thread behavior
720 * Create a new buffersize event. The event is sent downstream and notifies
721 * elements that they should provide a buffer of the specified dimensions.
723 * When the @async flag is set, a thread boundary is prefered.
725 * Returns: (transfer full): a new #GstEvent
728 gst_event_new_buffer_size (GstFormat format, gint64 minsize,
729 gint64 maxsize, gboolean async)
732 GstStructure *structure;
734 GST_CAT_INFO (GST_CAT_EVENT,
735 "creating buffersize format %s, minsize %" G_GINT64_FORMAT
736 ", maxsize %" G_GINT64_FORMAT ", async %d", gst_format_get_name (format),
737 minsize, maxsize, async);
739 structure = gst_structure_id_new (GST_QUARK (EVENT_BUFFER_SIZE),
740 GST_QUARK (FORMAT), GST_TYPE_FORMAT, format,
741 GST_QUARK (MINSIZE), G_TYPE_INT64, minsize,
742 GST_QUARK (MAXSIZE), G_TYPE_INT64, maxsize,
743 GST_QUARK (ASYNC), G_TYPE_BOOLEAN, async, NULL);
744 event = gst_event_new_custom (GST_EVENT_BUFFERSIZE, structure);
750 * gst_event_parse_buffer_size:
751 * @event: The event to query
752 * @format: (out): A pointer to store the format in
753 * @minsize: (out): A pointer to store the minsize in
754 * @maxsize: (out): A pointer to store the maxsize in
755 * @async: (out): A pointer to store the async-flag in
757 * Get the format, minsize, maxsize and async-flag in the buffersize event.
760 gst_event_parse_buffer_size (GstEvent * event, GstFormat * format,
761 gint64 * minsize, gint64 * maxsize, gboolean * async)
763 const GstStructure *structure;
765 g_return_if_fail (GST_IS_EVENT (event));
766 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_BUFFERSIZE);
768 structure = event->structure;
771 g_value_get_enum (gst_structure_id_get_value (structure,
772 GST_QUARK (FORMAT)));
775 g_value_get_int64 (gst_structure_id_get_value (structure,
776 GST_QUARK (MINSIZE)));
779 g_value_get_int64 (gst_structure_id_get_value (structure,
780 GST_QUARK (MAXSIZE)));
783 g_value_get_boolean (gst_structure_id_get_value (structure,
789 * @proportion: the proportion of the qos message
790 * @diff: The time difference of the last Clock sync
791 * @timestamp: The timestamp of the buffer
793 * Allocate a new qos event with the given values. This function calls
794 * gst_event_new_qos_full() with the type set to #GST_QOS_TYPE_OVERFLOW
795 * when diff is negative (buffers are in time) and #GST_QOS_TYPE_UNDERFLOW
796 * when @diff is positive (buffers are late).
798 * Returns: (transfer full): a new QOS event.
801 gst_event_new_qos (gdouble proportion, GstClockTimeDiff diff,
802 GstClockTime timestamp)
807 type = GST_QOS_TYPE_OVERFLOW;
809 type = GST_QOS_TYPE_UNDERFLOW;
811 return gst_event_new_qos_full (type, proportion, diff, timestamp);
815 * gst_event_new_qos_full:
816 * @type: the QoS type
817 * @proportion: the proportion of the qos message
818 * @diff: The time difference of the last Clock sync
819 * @timestamp: The timestamp of the buffer
821 * Allocate a new qos event with the given values.
822 * The QOS event is generated in an element that wants an upstream
823 * element to either reduce or increase its rate because of
824 * high/low CPU load or other resource usage such as network performance or
825 * throttling. Typically sinks generate these events for each buffer
828 * @type indicates the reason for the QoS event. #GST_QOS_TYPE_OVERFLOW is
829 * used when a buffer arrived in time or when the sink cannot keep up with
830 * the upstream datarate. #GST_QOS_TYPE_UNDERFLOW is when the sink is not
831 * receiving buffers fast enough and thus has to drop late buffers.
832 * #GST_QOS_TYPE_THROTTLE is used when the datarate is artificially limited
833 * by the application, for example to reduce power consumption.
835 * @proportion indicates the real-time performance of the streaming in the
836 * element that generated the QoS event (usually the sink). The value is
837 * generally computed based on more long term statistics about the streams
838 * timestamps compared to the clock.
839 * A value < 1.0 indicates that the upstream element is producing data faster
840 * than real-time. A value > 1.0 indicates that the upstream element is not
841 * producing data fast enough. 1.0 is the ideal @proportion value. The
842 * proportion value can safely be used to lower or increase the quality of
845 * @diff is the difference against the clock in running time of the last
846 * buffer that caused the element to generate the QOS event. A negative value
847 * means that the buffer with @timestamp arrived in time. A positive value
848 * indicates how late the buffer with @timestamp was. When throttling is
849 * enabled, @diff will be set to the requested throttling interval.
851 * @timestamp is the timestamp of the last buffer that cause the element
852 * to generate the QOS event. It is expressed in running time and thus an ever
855 * The upstream element can use the @diff and @timestamp values to decide
856 * whether to process more buffers. For possitive @diff, all buffers with
857 * timestamp <= @timestamp + @diff will certainly arrive late in the sink
858 * as well. A (negative) @diff value so that @timestamp + @diff would yield a
859 * result smaller than 0 is not allowed.
861 * The application can use general event probes to intercept the QoS
862 * event and implement custom application specific QoS handling.
864 * Returns: (transfer full): a new QOS event.
869 gst_event_new_qos_full (GstQOSType type, gdouble proportion,
870 GstClockTimeDiff diff, GstClockTime timestamp)
873 GstStructure *structure;
875 /* diff must be positive or timestamp + diff must be positive */
876 g_return_val_if_fail (diff >= 0 || -diff <= timestamp, NULL);
878 GST_CAT_INFO (GST_CAT_EVENT,
879 "creating qos type %d, proportion %lf, diff %" G_GINT64_FORMAT
880 ", timestamp %" GST_TIME_FORMAT, type, proportion,
881 diff, GST_TIME_ARGS (timestamp));
883 structure = gst_structure_id_new (GST_QUARK (EVENT_QOS),
884 GST_QUARK (TYPE), GST_TYPE_QOS_TYPE, type,
885 GST_QUARK (PROPORTION), G_TYPE_DOUBLE, proportion,
886 GST_QUARK (DIFF), G_TYPE_INT64, diff,
887 GST_QUARK (TIMESTAMP), G_TYPE_UINT64, timestamp, NULL);
888 event = gst_event_new_custom (GST_EVENT_QOS, structure);
894 * gst_event_parse_qos:
895 * @event: The event to query
896 * @proportion: (out): A pointer to store the proportion in
897 * @diff: (out): A pointer to store the diff in
898 * @timestamp: (out): A pointer to store the timestamp in
900 * Get the proportion, diff and timestamp in the qos event. See
901 * gst_event_new_qos() for more information about the different QoS values.
904 gst_event_parse_qos (GstEvent * event, gdouble * proportion,
905 GstClockTimeDiff * diff, GstClockTime * timestamp)
907 gst_event_parse_qos_full (event, NULL, proportion, diff, timestamp);
911 * gst_event_parse_qos_full:
912 * @event: The event to query
913 * @type: (out): A pointer to store the QoS type in
914 * @proportion: (out): A pointer to store the proportion in
915 * @diff: (out): A pointer to store the diff in
916 * @timestamp: (out): A pointer to store the timestamp in
918 * Get the type, proportion, diff and timestamp in the qos event. See
919 * gst_event_new_qos_full() for more information about the different QoS values.
924 gst_event_parse_qos_full (GstEvent * event, GstQOSType * type,
925 gdouble * proportion, GstClockTimeDiff * diff, GstClockTime * timestamp)
927 const GstStructure *structure;
929 g_return_if_fail (GST_IS_EVENT (event));
930 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_QOS);
932 structure = event->structure;
935 g_value_get_enum (gst_structure_id_get_value (structure,
939 g_value_get_double (gst_structure_id_get_value (structure,
940 GST_QUARK (PROPORTION)));
943 g_value_get_int64 (gst_structure_id_get_value (structure,
947 g_value_get_uint64 (gst_structure_id_get_value (structure,
948 GST_QUARK (TIMESTAMP)));
952 * gst_event_new_seek:
953 * @rate: The new playback rate
954 * @format: The format of the seek values
955 * @flags: The optional seek flags
956 * @start_type: The type and flags for the new start position
957 * @start: The value of the new start position
958 * @stop_type: The type and flags for the new stop position
959 * @stop: The value of the new stop position
961 * Allocate a new seek event with the given parameters.
963 * The seek event configures playback of the pipeline between @start to @stop
964 * at the speed given in @rate, also called a playback segment.
965 * The @start and @stop values are expressed in @format.
967 * A @rate of 1.0 means normal playback rate, 2.0 means double speed.
968 * Negatives values means backwards playback. A value of 0.0 for the
969 * rate is not allowed and should be accomplished instead by PAUSING the
972 * A pipeline has a default playback segment configured with a start
973 * position of 0, a stop position of -1 and a rate of 1.0. The currently
974 * configured playback segment can be queried with #GST_QUERY_SEGMENT.
976 * @start_type and @stop_type specify how to adjust the currently configured
977 * start and stop fields in playback segment. Adjustments can be made relative
978 * or absolute to the last configured values. A type of #GST_SEEK_TYPE_NONE
979 * means that the position should not be updated.
981 * When the rate is positive and @start has been updated, playback will start
982 * from the newly configured start position.
984 * For negative rates, playback will start from the newly configured stop
985 * position (if any). If the stop position if updated, it must be different from
986 * -1 for negative rates.
988 * It is not possible to seek relative to the current playback position, to do
989 * this, PAUSE the pipeline, query the current playback position with
990 * #GST_QUERY_POSITION and update the playback segment current position with a
991 * #GST_SEEK_TYPE_SET to the desired position.
993 * Returns: (transfer full): a new seek event.
996 gst_event_new_seek (gdouble rate, GstFormat format, GstSeekFlags flags,
997 GstSeekType start_type, gint64 start, GstSeekType stop_type, gint64 stop)
1000 GstStructure *structure;
1002 g_return_val_if_fail (rate != 0.0, NULL);
1004 if (format == GST_FORMAT_TIME) {
1005 GST_CAT_INFO (GST_CAT_EVENT,
1006 "creating seek rate %lf, format TIME, flags %d, "
1007 "start_type %d, start %" GST_TIME_FORMAT ", "
1008 "stop_type %d, stop %" GST_TIME_FORMAT,
1009 rate, flags, start_type, GST_TIME_ARGS (start),
1010 stop_type, GST_TIME_ARGS (stop));
1012 GST_CAT_INFO (GST_CAT_EVENT,
1013 "creating seek rate %lf, format %s, flags %d, "
1014 "start_type %d, start %" G_GINT64_FORMAT ", "
1015 "stop_type %d, stop %" G_GINT64_FORMAT,
1016 rate, gst_format_get_name (format), flags, start_type, start, stop_type,
1020 structure = gst_structure_id_new (GST_QUARK (EVENT_SEEK),
1021 GST_QUARK (RATE), G_TYPE_DOUBLE, rate,
1022 GST_QUARK (FORMAT), GST_TYPE_FORMAT, format,
1023 GST_QUARK (FLAGS), GST_TYPE_SEEK_FLAGS, flags,
1024 GST_QUARK (CUR_TYPE), GST_TYPE_SEEK_TYPE, start_type,
1025 GST_QUARK (CUR), G_TYPE_INT64, start,
1026 GST_QUARK (STOP_TYPE), GST_TYPE_SEEK_TYPE, stop_type,
1027 GST_QUARK (STOP), G_TYPE_INT64, stop, NULL);
1028 event = gst_event_new_custom (GST_EVENT_SEEK, structure);
1034 * gst_event_parse_seek:
1035 * @event: a seek event
1036 * @rate: (out): result location for the rate
1037 * @format: (out): result location for the stream format
1038 * @flags: (out): result location for the #GstSeekFlags
1039 * @start_type: (out): result location for the #GstSeekType of the start position
1040 * @start: (out): result location for the start postion expressed in @format
1041 * @stop_type: (out): result location for the #GstSeekType of the stop position
1042 * @stop: (out): result location for the stop postion expressed in @format
1044 * Parses a seek @event and stores the results in the given result locations.
1047 gst_event_parse_seek (GstEvent * event, gdouble * rate,
1048 GstFormat * format, GstSeekFlags * flags, GstSeekType * start_type,
1049 gint64 * start, GstSeekType * stop_type, gint64 * stop)
1051 const GstStructure *structure;
1053 g_return_if_fail (GST_IS_EVENT (event));
1054 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SEEK);
1056 structure = event->structure;
1059 g_value_get_double (gst_structure_id_get_value (structure,
1063 g_value_get_enum (gst_structure_id_get_value (structure,
1064 GST_QUARK (FORMAT)));
1067 g_value_get_flags (gst_structure_id_get_value (structure,
1068 GST_QUARK (FLAGS)));
1071 g_value_get_enum (gst_structure_id_get_value (structure,
1072 GST_QUARK (CUR_TYPE)));
1075 g_value_get_int64 (gst_structure_id_get_value (structure,
1079 g_value_get_enum (gst_structure_id_get_value (structure,
1080 GST_QUARK (STOP_TYPE)));
1083 g_value_get_int64 (gst_structure_id_get_value (structure,
1088 * gst_event_new_navigation:
1089 * @structure: (transfer full): description of the event. The event will take
1090 * ownership of the structure.
1092 * Create a new navigation event from the given description.
1094 * Returns: (transfer full): a new #GstEvent
1097 gst_event_new_navigation (GstStructure * structure)
1099 g_return_val_if_fail (structure != NULL, NULL);
1101 return gst_event_new_custom (GST_EVENT_NAVIGATION, structure);
1105 * gst_event_new_latency:
1106 * @latency: the new latency value
1108 * Create a new latency event. The event is sent upstream from the sinks and
1109 * notifies elements that they should add an additional @latency to the
1110 * running time before synchronising against the clock.
1112 * The latency is mostly used in live sinks and is always expressed in
1115 * Returns: (transfer full): a new #GstEvent
1120 gst_event_new_latency (GstClockTime latency)
1123 GstStructure *structure;
1125 GST_CAT_INFO (GST_CAT_EVENT,
1126 "creating latency event %" GST_TIME_FORMAT, GST_TIME_ARGS (latency));
1128 structure = gst_structure_id_new (GST_QUARK (EVENT_LATENCY),
1129 GST_QUARK (LATENCY), G_TYPE_UINT64, latency, NULL);
1130 event = gst_event_new_custom (GST_EVENT_LATENCY, structure);
1136 * gst_event_parse_latency:
1137 * @event: The event to query
1138 * @latency: (out): A pointer to store the latency in.
1140 * Get the latency in the latency event.
1145 gst_event_parse_latency (GstEvent * event, GstClockTime * latency)
1147 g_return_if_fail (GST_IS_EVENT (event));
1148 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_LATENCY);
1152 g_value_get_uint64 (gst_structure_id_get_value (event->structure,
1153 GST_QUARK (LATENCY)));
1157 * gst_event_new_step:
1158 * @format: the format of @amount
1159 * @amount: the amount of data to step
1160 * @rate: the step rate
1161 * @flush: flushing steps
1162 * @intermediate: intermediate steps
1164 * Create a new step event. The purpose of the step event is to instruct a sink
1165 * to skip @amount (expressed in @format) of media. It can be used to implement
1166 * stepping through the video frame by frame or for doing fast trick modes.
1168 * A rate of <= 0.0 is not allowed, pause the pipeline or reverse the playback
1169 * direction of the pipeline to get the same effect.
1171 * The @flush flag will clear any pending data in the pipeline before starting
1172 * the step operation.
1174 * The @intermediate flag instructs the pipeline that this step operation is
1175 * part of a larger step operation.
1177 * Returns: (transfer full): a new #GstEvent
1182 gst_event_new_step (GstFormat format, guint64 amount, gdouble rate,
1183 gboolean flush, gboolean intermediate)
1186 GstStructure *structure;
1188 g_return_val_if_fail (rate > 0.0, NULL);
1190 GST_CAT_INFO (GST_CAT_EVENT, "creating step event");
1192 structure = gst_structure_id_new (GST_QUARK (EVENT_STEP),
1193 GST_QUARK (FORMAT), GST_TYPE_FORMAT, format,
1194 GST_QUARK (AMOUNT), G_TYPE_UINT64, amount,
1195 GST_QUARK (RATE), G_TYPE_DOUBLE, rate,
1196 GST_QUARK (FLUSH), G_TYPE_BOOLEAN, flush,
1197 GST_QUARK (INTERMEDIATE), G_TYPE_BOOLEAN, intermediate, NULL);
1198 event = gst_event_new_custom (GST_EVENT_STEP, structure);
1204 * gst_event_parse_step:
1205 * @event: The event to query
1206 * @format: (out) (allow-none): a pointer to store the format in
1207 * @amount: (out) (allow-none): a pointer to store the amount in
1208 * @rate: (out) (allow-none): a pointer to store the rate in
1209 * @flush: (out) (allow-none): a pointer to store the flush boolean in
1210 * @intermediate: (out) (allow-none): a pointer to store the intermediate
1213 * Parse the step event.
1218 gst_event_parse_step (GstEvent * event, GstFormat * format, guint64 * amount,
1219 gdouble * rate, gboolean * flush, gboolean * intermediate)
1221 const GstStructure *structure;
1223 g_return_if_fail (GST_IS_EVENT (event));
1224 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_STEP);
1226 structure = event->structure;
1228 *format = g_value_get_enum (gst_structure_id_get_value (structure,
1229 GST_QUARK (FORMAT)));
1231 *amount = g_value_get_uint64 (gst_structure_id_get_value (structure,
1232 GST_QUARK (AMOUNT)));
1234 *rate = g_value_get_double (gst_structure_id_get_value (structure,
1237 *flush = g_value_get_boolean (gst_structure_id_get_value (structure,
1238 GST_QUARK (FLUSH)));
1240 *intermediate = g_value_get_boolean (gst_structure_id_get_value (structure,
1241 GST_QUARK (INTERMEDIATE)));
1245 * gst_event_new_reconfigure:
1247 * Create a new reconfigure event. The purpose of the reconfingure event is
1248 * to travel upstream and make elements renegotiate their caps or reconfigure
1249 * their buffer pools. This is useful when changing properties on elements
1250 * or changing the topology of the pipeline.
1252 * Returns: (transfer full): a new #GstEvent
1257 gst_event_new_reconfigure (void)
1261 GST_CAT_INFO (GST_CAT_EVENT, "creating reconfigure event");
1263 event = gst_event_new_custom (GST_EVENT_RECONFIGURE, NULL);
1269 * gst_event_new_sink_message:
1270 * @msg: (transfer none): the #GstMessage to be posted
1272 * Create a new sink-message event. The purpose of the sink-message event is
1273 * to instruct a sink to post the message contained in the event synchronized
1276 * Returns: (transfer full): a new #GstEvent
1280 /* FIXME 0.11: take ownership of msg for consistency? */
1282 gst_event_new_sink_message (GstMessage * msg)
1285 GstStructure *structure;
1287 g_return_val_if_fail (msg != NULL, NULL);
1289 GST_CAT_INFO (GST_CAT_EVENT, "creating sink-message event");
1291 structure = gst_structure_id_new (GST_QUARK (EVENT_SINK_MESSAGE),
1292 GST_QUARK (MESSAGE), GST_TYPE_MESSAGE, msg, NULL);
1293 event = gst_event_new_custom (GST_EVENT_SINK_MESSAGE, structure);
1299 * gst_event_parse_sink_message:
1300 * @event: The event to query
1301 * @msg: (out) (transfer full): a pointer to store the #GstMessage in.
1303 * Parse the sink-message event. Unref @msg after usage.
1308 gst_event_parse_sink_message (GstEvent * event, GstMessage ** msg)
1310 const GstStructure *structure;
1312 g_return_if_fail (GST_IS_EVENT (event));
1313 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SINK_MESSAGE);
1315 structure = event->structure;
1318 GST_MESSAGE (g_value_dup_boxed (gst_structure_id_get_value
1319 (structure, GST_QUARK (MESSAGE))));