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_EOS, "eos", 0},
111 {GST_EVENT_CAPS, "caps", 0},
112 {GST_EVENT_SEGMENT, "segment", 0},
113 {GST_EVENT_TAG, "tag", 0},
114 {GST_EVENT_BUFFERSIZE, "buffersize", 0},
115 {GST_EVENT_SINK_MESSAGE, "sink-message", 0},
116 {GST_EVENT_QOS, "qos", 0},
117 {GST_EVENT_SEEK, "seek", 0},
118 {GST_EVENT_NAVIGATION, "navigation", 0},
119 {GST_EVENT_LATENCY, "latency", 0},
120 {GST_EVENT_STEP, "step", 0},
121 {GST_EVENT_RECONFIGURE, "reconfigure", 0},
122 {GST_EVENT_CUSTOM_UPSTREAM, "custom-upstream", 0},
123 {GST_EVENT_CUSTOM_DOWNSTREAM, "custom-downstream", 0},
124 {GST_EVENT_CUSTOM_DOWNSTREAM_OOB, "custom-downstream-oob", 0},
125 {GST_EVENT_CUSTOM_DOWNSTREAM_STICKY, "custom-downstream-sticky", 0},
126 {GST_EVENT_CUSTOM_BOTH, "custom-both", 0},
127 {GST_EVENT_CUSTOM_BOTH_OOB, "custom-both-oob", 0},
132 GST_DEFINE_MINI_OBJECT_TYPE (GstEvent, gst_event);
135 _priv_gst_event_initialize (void)
139 _gst_event_type = gst_event_get_type ();
141 g_type_class_ref (gst_seek_flags_get_type ());
142 g_type_class_ref (gst_seek_type_get_type ());
144 for (i = 0; event_quarks[i].name; i++) {
145 event_quarks[i].quark = g_quark_from_static_string (event_quarks[i].name);
150 * gst_event_type_get_name:
151 * @type: the event type
153 * Get a printable name for the given event type. Do not modify or free.
155 * Returns: a reference to the static name of the event.
158 gst_event_type_get_name (GstEventType type)
162 for (i = 0; event_quarks[i].name; i++) {
163 if (type == event_quarks[i].type)
164 return event_quarks[i].name;
170 * gst_event_type_to_quark:
171 * @type: the event type
173 * Get the unique quark for the given event type.
175 * Returns: the quark associated with the event type
178 gst_event_type_to_quark (GstEventType type)
182 for (i = 0; event_quarks[i].name; i++) {
183 if (type == event_quarks[i].type)
184 return event_quarks[i].quark;
190 * gst_event_type_get_flags:
191 * @type: a #GstEventType
193 * Gets the #GstEventTypeFlags associated with @type.
195 * Returns: a #GstEventTypeFlags.
198 gst_event_type_get_flags (GstEventType type)
200 GstEventTypeFlags ret;
202 ret = type & ((1 << GST_EVENT_STICKY_SHIFT) - 1);
208 _gst_event_free (GstEvent * event)
212 g_return_if_fail (event != NULL);
213 g_return_if_fail (GST_IS_EVENT (event));
215 GST_CAT_LOG (GST_CAT_EVENT, "freeing event %p type %s", event,
216 GST_EVENT_TYPE_NAME (event));
218 s = GST_EVENT_STRUCTURE (event);
221 gst_structure_set_parent_refcount (s, NULL);
222 gst_structure_free (s);
225 g_slice_free1 (GST_MINI_OBJECT_SIZE (event), event);
228 static void gst_event_init (GstEventImpl * event, gsize size,
232 _gst_event_copy (GstEvent * event)
237 copy = g_slice_new0 (GstEventImpl);
239 gst_event_init (copy, sizeof (GstEventImpl), GST_EVENT_TYPE (event));
241 GST_EVENT_TIMESTAMP (copy) = GST_EVENT_TIMESTAMP (event);
242 GST_EVENT_SEQNUM (copy) = GST_EVENT_SEQNUM (event);
244 s = GST_EVENT_STRUCTURE (event);
246 GST_EVENT_STRUCTURE (copy) = gst_structure_copy (s);
247 gst_structure_set_parent_refcount (GST_EVENT_STRUCTURE (copy),
248 ©->event.mini_object.refcount);
250 return GST_EVENT_CAST (copy);
254 gst_event_init (GstEventImpl * event, gsize size, GstEventType type)
256 gst_mini_object_init (GST_MINI_OBJECT_CAST (event), _gst_event_type, size);
258 event->event.mini_object.copy = (GstMiniObjectCopyFunction) _gst_event_copy;
259 event->event.mini_object.free = (GstMiniObjectFreeFunction) _gst_event_free;
261 GST_EVENT_TYPE (event) = type;
262 GST_EVENT_TIMESTAMP (event) = GST_CLOCK_TIME_NONE;
263 GST_EVENT_SEQNUM (event) = gst_util_seqnum_next ();
267 gst_event_new (GstEventType type)
271 event = g_slice_new0 (GstEventImpl);
273 GST_CAT_DEBUG (GST_CAT_EVENT, "creating new event %p %s %d", event,
274 gst_event_type_get_name (type), type);
276 gst_event_init (event, sizeof (GstEventImpl), type);
278 return GST_EVENT_CAST (event);
282 * gst_event_new_custom:
283 * @type: The type of the new event
284 * @structure: (transfer full): the structure for the event. The event will
285 * take ownership of the structure.
287 * Create a new custom-typed event. This can be used for anything not
288 * handled by other event-specific functions to pass an event to another
291 * Make sure to allocate an event type with the #GST_EVENT_MAKE_TYPE macro,
292 * assigning a free number and filling in the correct direction and
293 * serialization flags.
295 * New custom events can also be created by subclassing the event type if
298 * Returns: (transfer full): the new custom event.
301 gst_event_new_custom (GstEventType type, GstStructure * structure)
305 /* structure must not have a parent */
306 event = gst_event_new (type);
308 if (!gst_structure_set_parent_refcount (structure,
309 &event->mini_object.refcount))
312 GST_EVENT_STRUCTURE (event) = structure;
319 gst_event_unref (event);
320 g_warning ("structure is already owned by another object");
326 * gst_event_get_structure:
327 * @event: The #GstEvent.
329 * Access the structure of the event.
331 * Returns: The structure of the event. The structure is still
332 * owned by the event, which means that you should not free it and
333 * that the pointer becomes invalid when you free the event.
338 gst_event_get_structure (GstEvent * event)
340 g_return_val_if_fail (GST_IS_EVENT (event), NULL);
342 return GST_EVENT_STRUCTURE (event);
346 * gst_event_writable_structure:
347 * @event: The #GstEvent.
349 * Get a writable version of the structure.
351 * Returns: The structure of the event. The structure is still
352 * owned by the event, which means that you should not free it and
353 * that the pointer becomes invalid when you free the event.
354 * This function checks if @event is writable and will never return NULL.
359 gst_event_writable_structure (GstEvent * event)
361 GstStructure *structure;
363 g_return_val_if_fail (GST_IS_EVENT (event), NULL);
364 g_return_val_if_fail (gst_event_is_writable (event), NULL);
366 structure = GST_EVENT_STRUCTURE (event);
368 if (structure == NULL) {
370 gst_structure_new_id_empty (gst_event_type_to_quark (GST_EVENT_TYPE
372 gst_structure_set_parent_refcount (structure, &event->mini_object.refcount);
373 GST_EVENT_STRUCTURE (event) = structure;
379 * gst_event_has_name:
380 * @event: The #GstEvent.
381 * @name: name to check
383 * Checks if @event has the given @name. This function is usually used to
384 * check the name of a custom event.
386 * Returns: %TRUE if @name matches the name of the event structure.
391 gst_event_has_name (GstEvent * event, const gchar * name)
393 g_return_val_if_fail (GST_IS_EVENT (event), FALSE);
395 if (GST_EVENT_STRUCTURE (event) == NULL)
398 return gst_structure_has_name (GST_EVENT_STRUCTURE (event), name);
402 * gst_event_get_seqnum:
403 * @event: A #GstEvent.
405 * Retrieve the sequence number of a event.
407 * Events have ever-incrementing sequence numbers, which may also be set
408 * explicitly via gst_event_set_seqnum(). Sequence numbers are typically used to
409 * indicate that a event corresponds to some other set of events or messages,
410 * for example an EOS event corresponding to a SEEK event. It is considered good
411 * practice to make this correspondence when possible, though it is not
414 * Note that events and messages share the same sequence number incrementor;
415 * two events or messages will never have the same sequence number unless
416 * that correspondence was made explicitly.
418 * Returns: The event's sequence number.
425 gst_event_get_seqnum (GstEvent * event)
427 g_return_val_if_fail (GST_IS_EVENT (event), -1);
429 return GST_EVENT_SEQNUM (event);
433 * gst_event_set_seqnum:
434 * @event: A #GstEvent.
435 * @seqnum: A sequence number.
437 * Set the sequence number of a event.
439 * This function might be called by the creator of a event to indicate that the
440 * event relates to other events or messages. See gst_event_get_seqnum() for
448 gst_event_set_seqnum (GstEvent * event, guint32 seqnum)
450 g_return_if_fail (GST_IS_EVENT (event));
452 GST_EVENT_SEQNUM (event) = seqnum;
455 /* FIXME 0.11: It would be nice to have flush events
456 * that don't reset the running time in the sinks
460 * gst_event_new_flush_start:
462 * Allocate a new flush start event. The flush start event can be sent
463 * upstream and downstream and travels out-of-bounds with the dataflow.
465 * It marks pads as being flushing and will make them return
466 * #GST_FLOW_WRONG_STATE when used for data flow with gst_pad_push(),
467 * gst_pad_chain(), gst_pad_alloc_buffer(), gst_pad_get_range() and
468 * gst_pad_pull_range(). Any event (except a #GST_EVENT_FLUSH_STOP) received
469 * on a flushing pad will return %FALSE immediately.
471 * Elements should unlock any blocking functions and exit their streaming
472 * functions as fast as possible when this event is received.
474 * This event is typically generated after a seek to flush out all queued data
475 * in the pipeline so that the new media is played as soon as possible.
477 * Returns: (transfer full): a new flush start event.
480 gst_event_new_flush_start (void)
482 return gst_event_new (GST_EVENT_FLUSH_START);
486 * gst_event_new_flush_stop:
487 * @reset_time: if time should be reset
489 * Allocate a new flush stop event. The flush stop event can be sent
490 * upstream and downstream and travels serialized with the dataflow.
491 * It is typically sent after sending a FLUSH_START event to make the
492 * pads accept data again.
494 * Elements can process this event synchronized with the dataflow since
495 * the preceeding FLUSH_START event stopped the dataflow.
497 * This event is typically generated to complete a seek and to resume
500 * Returns: (transfer full): a new flush stop event.
503 gst_event_new_flush_stop (gboolean reset_time)
507 GST_CAT_INFO (GST_CAT_EVENT, "creating flush stop %d", reset_time);
509 event = gst_event_new_custom (GST_EVENT_FLUSH_STOP,
510 gst_structure_new_id (GST_QUARK (EVENT_FLUSH_STOP),
511 GST_QUARK (RESET_TIME), G_TYPE_BOOLEAN, reset_time, NULL));
517 * gst_event_parse_flush_stop:
518 * @event: The event to parse
519 * @reset_time: (out): if time should be reset
521 * Parse the FLUSH_STOP event and retrieve the @reset_time member.
524 gst_event_parse_flush_stop (GstEvent * event, gboolean * reset_time)
526 GstStructure *structure;
528 g_return_if_fail (GST_IS_EVENT (event));
529 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_FLUSH_STOP);
531 structure = GST_EVENT_STRUCTURE (event);
532 if (G_LIKELY (reset_time))
534 g_value_get_boolean (gst_structure_id_get_value (structure,
535 GST_QUARK (RESET_TIME)));
541 * Create a new EOS event. The eos event can only travel downstream
542 * synchronized with the buffer flow. Elements that receive the EOS
543 * event on a pad can return #GST_FLOW_UNEXPECTED as a #GstFlowReturn
544 * when data after the EOS event arrives.
546 * The EOS event will travel down to the sink elements in the pipeline
547 * which will then post the #GST_MESSAGE_EOS on the bus after they have
548 * finished playing any buffered data.
550 * When all sinks have posted an EOS message, an EOS message is
551 * forwarded to the application.
553 * The EOS event itself will not cause any state transitions of the pipeline.
555 * Returns: (transfer full): the new EOS event.
558 gst_event_new_eos (void)
560 return gst_event_new (GST_EVENT_EOS);
564 * gst_event_new_caps:
565 * @caps: (transfer none): a #GstCaps
567 * Create a new CAPS event for @caps. The caps event can only travel downstream
568 * synchronized with the buffer flow and contains the format of the buffers
569 * that will follow after the event.
571 * Returns: (transfer full): the new CAPS event.
574 gst_event_new_caps (GstCaps * caps)
578 g_return_val_if_fail (caps != NULL, NULL);
579 g_return_val_if_fail (gst_caps_is_fixed (caps), NULL);
581 GST_CAT_INFO (GST_CAT_EVENT, "creating caps event %" GST_PTR_FORMAT, caps);
583 event = gst_event_new_custom (GST_EVENT_CAPS,
584 gst_structure_new_id (GST_QUARK (EVENT_CAPS),
585 GST_QUARK (CAPS), GST_TYPE_CAPS, caps, NULL));
591 * gst_event_parse_caps:
592 * @event: The event to parse
593 * @caps: (out): A pointer to the caps
595 * Get the caps from @event. The caps remains valid as long as @event remains
599 gst_event_parse_caps (GstEvent * event, GstCaps ** caps)
601 GstStructure *structure;
603 g_return_if_fail (GST_IS_EVENT (event));
604 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_CAPS);
606 structure = GST_EVENT_STRUCTURE (event);
609 g_value_get_boxed (gst_structure_id_get_value (structure,
614 * gst_event_new_segment:
615 * @segment: (transfer none): a #GstSegment
617 * Create a new SEGMENT event for @segment. The segment event can only travel
618 * downstream synchronized with the buffer flow and contains timing information
619 * and playback properties for the buffers that will follow.
621 * The newsegment event marks the range of buffers to be processed. All
622 * data not within the segment range is not to be processed. This can be
623 * used intelligently by plugins to apply more efficient methods of skipping
624 * unneeded data. The valid range is expressed with the @start and @stop
627 * The time value of the segment is used in conjunction with the start
628 * value to convert the buffer timestamps into the stream time. This is
629 * usually done in sinks to report the current stream_time.
630 * @time represents the stream_time of a buffer carrying a timestamp of
631 * @start. @time cannot be -1.
633 * @start cannot be -1, @stop can be -1. If there
634 * is a valid @stop given, it must be greater or equal the @start, including
635 * when the indicated playback @rate is < 0.
637 * The @applied_rate value provides information about any rate adjustment that
638 * has already been made to the timestamps and content on the buffers of the
639 * stream. (@rate * @applied_rate) should always equal the rate that has been
640 * requested for playback. For example, if an element has an input segment
641 * with intended playback @rate of 2.0 and applied_rate of 1.0, it can adjust
642 * incoming timestamps and buffer content by half and output a newsegment event
643 * with @rate of 1.0 and @applied_rate of 2.0
645 * After a newsegment event, the buffer stream time is calculated with:
647 * time + (TIMESTAMP(buf) - start) * ABS (rate * applied_rate)
649 * Returns: (transfer full): the new SEGMENT event.
652 gst_event_new_segment (const GstSegment * segment)
656 g_return_val_if_fail (segment != NULL, NULL);
657 g_return_val_if_fail (segment->rate != 0.0, NULL);
658 g_return_val_if_fail (segment->applied_rate != 0.0, NULL);
659 g_return_val_if_fail (segment->format != GST_FORMAT_UNDEFINED, NULL);
661 GST_CAT_INFO (GST_CAT_EVENT, "creating segment event %" GST_SEGMENT_FORMAT,
664 event = gst_event_new_custom (GST_EVENT_SEGMENT,
665 gst_structure_new_id (GST_QUARK (EVENT_SEGMENT),
666 GST_QUARK (SEGMENT), GST_TYPE_SEGMENT, segment, NULL));
672 * gst_event_parse_segment:
673 * @event: The event to parse
674 * @segment: (out) (transfer none): a pointer to a #GstSegment
676 * Parses a segment @event and stores the result in the given @segment location.
677 * @segment remains valid only until the @event is freed. Don't modify the segment
678 * and make a copy if you want to modify it or store it for later use.
681 gst_event_parse_segment (GstEvent * event, const GstSegment ** segment)
683 GstStructure *structure;
685 g_return_if_fail (GST_IS_EVENT (event));
686 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SEGMENT);
689 structure = GST_EVENT_STRUCTURE (event);
690 *segment = g_value_get_boxed (gst_structure_id_get_value (structure,
691 GST_QUARK (SEGMENT)));
696 * gst_event_copy_segment:
697 * @event: The event to parse
698 * @segment: a pointer to a #GstSegment
700 * Parses a segment @event and copies the #GstSegment into the location
704 gst_event_copy_segment (GstEvent * event, GstSegment * segment)
706 const GstSegment *src;
708 g_return_if_fail (GST_IS_EVENT (event));
709 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SEGMENT);
712 gst_event_parse_segment (event, &src);
713 gst_segment_copy_into (src, segment);
719 * @taglist: (transfer full): metadata list. The event will take ownership
722 * Generates a metadata tag event from the given @taglist.
724 * Returns: (transfer full): a new #GstEvent
727 gst_event_new_tag (GstTagList * taglist)
729 g_return_val_if_fail (taglist != NULL, NULL);
731 return gst_event_new_custom (GST_EVENT_TAG, (GstStructure *) taglist);
735 * gst_event_parse_tag:
736 * @event: a tag event
737 * @taglist: (out) (transfer none): pointer to metadata list
739 * Parses a tag @event and stores the results in the given @taglist location.
740 * No reference to the taglist will be returned, it remains valid only until
741 * the @event is freed. Don't modify or free the taglist, make a copy if you
742 * want to modify it or store it for later use.
745 gst_event_parse_tag (GstEvent * event, GstTagList ** taglist)
747 g_return_if_fail (GST_IS_EVENT (event));
748 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_TAG);
751 *taglist = (GstTagList *) GST_EVENT_STRUCTURE (event);
754 /* buffersize event */
756 * gst_event_new_buffer_size:
757 * @format: buffer format
758 * @minsize: minimum buffer size
759 * @maxsize: maximum buffer size
760 * @async: thread behavior
762 * Create a new buffersize event. The event is sent downstream and notifies
763 * elements that they should provide a buffer of the specified dimensions.
765 * When the @async flag is set, a thread boundary is preferred.
767 * Returns: (transfer full): a new #GstEvent
770 gst_event_new_buffer_size (GstFormat format, gint64 minsize,
771 gint64 maxsize, gboolean async)
774 GstStructure *structure;
776 GST_CAT_INFO (GST_CAT_EVENT,
777 "creating buffersize format %s, minsize %" G_GINT64_FORMAT
778 ", maxsize %" G_GINT64_FORMAT ", async %d", gst_format_get_name (format),
779 minsize, maxsize, async);
781 structure = gst_structure_new_id (GST_QUARK (EVENT_BUFFER_SIZE),
782 GST_QUARK (FORMAT), GST_TYPE_FORMAT, format,
783 GST_QUARK (MINSIZE), G_TYPE_INT64, minsize,
784 GST_QUARK (MAXSIZE), G_TYPE_INT64, maxsize,
785 GST_QUARK (ASYNC), G_TYPE_BOOLEAN, async, NULL);
786 event = gst_event_new_custom (GST_EVENT_BUFFERSIZE, structure);
792 * gst_event_parse_buffer_size:
793 * @event: The event to query
794 * @format: (out): A pointer to store the format in
795 * @minsize: (out): A pointer to store the minsize in
796 * @maxsize: (out): A pointer to store the maxsize in
797 * @async: (out): A pointer to store the async-flag in
799 * Get the format, minsize, maxsize and async-flag in the buffersize event.
802 gst_event_parse_buffer_size (GstEvent * event, GstFormat * format,
803 gint64 * minsize, gint64 * maxsize, gboolean * async)
805 const GstStructure *structure;
807 g_return_if_fail (GST_IS_EVENT (event));
808 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_BUFFERSIZE);
810 structure = GST_EVENT_STRUCTURE (event);
812 *format = (GstFormat)
813 g_value_get_enum (gst_structure_id_get_value (structure,
814 GST_QUARK (FORMAT)));
817 g_value_get_int64 (gst_structure_id_get_value (structure,
818 GST_QUARK (MINSIZE)));
821 g_value_get_int64 (gst_structure_id_get_value (structure,
822 GST_QUARK (MAXSIZE)));
825 g_value_get_boolean (gst_structure_id_get_value (structure,
831 * @type: the QoS type
832 * @proportion: the proportion of the qos message
833 * @diff: The time difference of the last Clock sync
834 * @timestamp: The timestamp of the buffer
836 * Allocate a new qos event with the given values.
837 * The QOS event is generated in an element that wants an upstream
838 * element to either reduce or increase its rate because of
839 * high/low CPU load or other resource usage such as network performance or
840 * throttling. Typically sinks generate these events for each buffer
843 * @type indicates the reason for the QoS event. #GST_QOS_TYPE_OVERFLOW is
844 * used when a buffer arrived in time or when the sink cannot keep up with
845 * the upstream datarate. #GST_QOS_TYPE_UNDERFLOW is when the sink is not
846 * receiving buffers fast enough and thus has to drop late buffers.
847 * #GST_QOS_TYPE_THROTTLE is used when the datarate is artificially limited
848 * by the application, for example to reduce power consumption.
850 * @proportion indicates the real-time performance of the streaming in the
851 * element that generated the QoS event (usually the sink). The value is
852 * generally computed based on more long term statistics about the streams
853 * timestamps compared to the clock.
854 * A value < 1.0 indicates that the upstream element is producing data faster
855 * than real-time. A value > 1.0 indicates that the upstream element is not
856 * producing data fast enough. 1.0 is the ideal @proportion value. The
857 * proportion value can safely be used to lower or increase the quality of
860 * @diff is the difference against the clock in running time of the last
861 * buffer that caused the element to generate the QOS event. A negative value
862 * means that the buffer with @timestamp arrived in time. A positive value
863 * indicates how late the buffer with @timestamp was. When throttling is
864 * enabled, @diff will be set to the requested throttling interval.
866 * @timestamp is the timestamp of the last buffer that cause the element
867 * to generate the QOS event. It is expressed in running time and thus an ever
870 * The upstream element can use the @diff and @timestamp values to decide
871 * whether to process more buffers. For possitive @diff, all buffers with
872 * timestamp <= @timestamp + @diff will certainly arrive late in the sink
873 * as well. A (negative) @diff value so that @timestamp + @diff would yield a
874 * result smaller than 0 is not allowed.
876 * The application can use general event probes to intercept the QoS
877 * event and implement custom application specific QoS handling.
879 * Returns: (transfer full): a new QOS event.
882 gst_event_new_qos (GstQOSType type, gdouble proportion,
883 GstClockTimeDiff diff, GstClockTime timestamp)
886 GstStructure *structure;
888 /* diff must be positive or timestamp + diff must be positive */
889 g_return_val_if_fail (diff >= 0 || -diff <= timestamp, NULL);
891 GST_CAT_LOG (GST_CAT_EVENT,
892 "creating qos type %d, proportion %lf, diff %" G_GINT64_FORMAT
893 ", timestamp %" GST_TIME_FORMAT, type, proportion,
894 diff, GST_TIME_ARGS (timestamp));
896 structure = gst_structure_new_id (GST_QUARK (EVENT_QOS),
897 GST_QUARK (TYPE), GST_TYPE_QOS_TYPE, type,
898 GST_QUARK (PROPORTION), G_TYPE_DOUBLE, proportion,
899 GST_QUARK (DIFF), G_TYPE_INT64, diff,
900 GST_QUARK (TIMESTAMP), G_TYPE_UINT64, timestamp, NULL);
901 event = gst_event_new_custom (GST_EVENT_QOS, structure);
907 * gst_event_parse_qos:
908 * @event: The event to query
909 * @type: (out): A pointer to store the QoS type in
910 * @proportion: (out): A pointer to store the proportion in
911 * @diff: (out): A pointer to store the diff in
912 * @timestamp: (out): A pointer to store the timestamp in
914 * Get the type, proportion, diff and timestamp in the qos event. See
915 * gst_event_new_qos() for more information about the different QoS values.
918 gst_event_parse_qos (GstEvent * event, GstQOSType * type,
919 gdouble * proportion, GstClockTimeDiff * diff, GstClockTime * timestamp)
921 const GstStructure *structure;
923 g_return_if_fail (GST_IS_EVENT (event));
924 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_QOS);
926 structure = GST_EVENT_STRUCTURE (event);
929 g_value_get_enum (gst_structure_id_get_value (structure,
933 g_value_get_double (gst_structure_id_get_value (structure,
934 GST_QUARK (PROPORTION)));
937 g_value_get_int64 (gst_structure_id_get_value (structure,
941 g_value_get_uint64 (gst_structure_id_get_value (structure,
942 GST_QUARK (TIMESTAMP)));
946 * gst_event_new_seek:
947 * @rate: The new playback rate
948 * @format: The format of the seek values
949 * @flags: The optional seek flags
950 * @start_type: The type and flags for the new start position
951 * @start: The value of the new start position
952 * @stop_type: The type and flags for the new stop position
953 * @stop: The value of the new stop position
955 * Allocate a new seek event with the given parameters.
957 * The seek event configures playback of the pipeline between @start to @stop
958 * at the speed given in @rate, also called a playback segment.
959 * The @start and @stop values are expressed in @format.
961 * A @rate of 1.0 means normal playback rate, 2.0 means double speed.
962 * Negatives values means backwards playback. A value of 0.0 for the
963 * rate is not allowed and should be accomplished instead by PAUSING the
966 * A pipeline has a default playback segment configured with a start
967 * position of 0, a stop position of -1 and a rate of 1.0. The currently
968 * configured playback segment can be queried with #GST_QUERY_SEGMENT.
970 * @start_type and @stop_type specify how to adjust the currently configured
971 * start and stop fields in playback segment. Adjustments can be made relative
972 * or absolute to the last configured values. A type of #GST_SEEK_TYPE_NONE
973 * means that the position should not be updated.
975 * When the rate is positive and @start has been updated, playback will start
976 * from the newly configured start position.
978 * For negative rates, playback will start from the newly configured stop
979 * position (if any). If the stop position if updated, it must be different from
980 * -1 for negative rates.
982 * It is not possible to seek relative to the current playback position, to do
983 * this, PAUSE the pipeline, query the current playback position with
984 * #GST_QUERY_POSITION and update the playback segment current position with a
985 * #GST_SEEK_TYPE_SET to the desired position.
987 * Returns: (transfer full): a new seek event.
990 gst_event_new_seek (gdouble rate, GstFormat format, GstSeekFlags flags,
991 GstSeekType start_type, gint64 start, GstSeekType stop_type, gint64 stop)
994 GstStructure *structure;
996 g_return_val_if_fail (rate != 0.0, NULL);
998 if (format == GST_FORMAT_TIME) {
999 GST_CAT_INFO (GST_CAT_EVENT,
1000 "creating seek rate %lf, format TIME, flags %d, "
1001 "start_type %d, start %" GST_TIME_FORMAT ", "
1002 "stop_type %d, stop %" GST_TIME_FORMAT,
1003 rate, flags, start_type, GST_TIME_ARGS (start),
1004 stop_type, GST_TIME_ARGS (stop));
1006 GST_CAT_INFO (GST_CAT_EVENT,
1007 "creating seek rate %lf, format %s, flags %d, "
1008 "start_type %d, start %" G_GINT64_FORMAT ", "
1009 "stop_type %d, stop %" G_GINT64_FORMAT,
1010 rate, gst_format_get_name (format), flags, start_type, start, stop_type,
1014 structure = gst_structure_new_id (GST_QUARK (EVENT_SEEK),
1015 GST_QUARK (RATE), G_TYPE_DOUBLE, rate,
1016 GST_QUARK (FORMAT), GST_TYPE_FORMAT, format,
1017 GST_QUARK (FLAGS), GST_TYPE_SEEK_FLAGS, flags,
1018 GST_QUARK (CUR_TYPE), GST_TYPE_SEEK_TYPE, start_type,
1019 GST_QUARK (CUR), G_TYPE_INT64, start,
1020 GST_QUARK (STOP_TYPE), GST_TYPE_SEEK_TYPE, stop_type,
1021 GST_QUARK (STOP), G_TYPE_INT64, stop, NULL);
1022 event = gst_event_new_custom (GST_EVENT_SEEK, structure);
1028 * gst_event_parse_seek:
1029 * @event: a seek event
1030 * @rate: (out): result location for the rate
1031 * @format: (out): result location for the stream format
1032 * @flags: (out): result location for the #GstSeekFlags
1033 * @start_type: (out): result location for the #GstSeekType of the start position
1034 * @start: (out): result location for the start postion expressed in @format
1035 * @stop_type: (out): result location for the #GstSeekType of the stop position
1036 * @stop: (out): result location for the stop postion expressed in @format
1038 * Parses a seek @event and stores the results in the given result locations.
1041 gst_event_parse_seek (GstEvent * event, gdouble * rate,
1042 GstFormat * format, GstSeekFlags * flags, GstSeekType * start_type,
1043 gint64 * start, GstSeekType * stop_type, gint64 * stop)
1045 const GstStructure *structure;
1047 g_return_if_fail (GST_IS_EVENT (event));
1048 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SEEK);
1050 structure = GST_EVENT_STRUCTURE (event);
1053 g_value_get_double (gst_structure_id_get_value (structure,
1056 *format = (GstFormat)
1057 g_value_get_enum (gst_structure_id_get_value (structure,
1058 GST_QUARK (FORMAT)));
1060 *flags = (GstSeekFlags)
1061 g_value_get_flags (gst_structure_id_get_value (structure,
1062 GST_QUARK (FLAGS)));
1064 *start_type = (GstSeekType)
1065 g_value_get_enum (gst_structure_id_get_value (structure,
1066 GST_QUARK (CUR_TYPE)));
1069 g_value_get_int64 (gst_structure_id_get_value (structure,
1072 *stop_type = (GstSeekType)
1073 g_value_get_enum (gst_structure_id_get_value (structure,
1074 GST_QUARK (STOP_TYPE)));
1077 g_value_get_int64 (gst_structure_id_get_value (structure,
1082 * gst_event_new_navigation:
1083 * @structure: (transfer full): description of the event. The event will take
1084 * ownership of the structure.
1086 * Create a new navigation event from the given description.
1088 * Returns: (transfer full): a new #GstEvent
1091 gst_event_new_navigation (GstStructure * structure)
1093 g_return_val_if_fail (structure != NULL, NULL);
1095 return gst_event_new_custom (GST_EVENT_NAVIGATION, structure);
1099 * gst_event_new_latency:
1100 * @latency: the new latency value
1102 * Create a new latency event. The event is sent upstream from the sinks and
1103 * notifies elements that they should add an additional @latency to the
1104 * running time before synchronising against the clock.
1106 * The latency is mostly used in live sinks and is always expressed in
1109 * Returns: (transfer full): a new #GstEvent
1114 gst_event_new_latency (GstClockTime latency)
1117 GstStructure *structure;
1119 GST_CAT_INFO (GST_CAT_EVENT,
1120 "creating latency event %" GST_TIME_FORMAT, GST_TIME_ARGS (latency));
1122 structure = gst_structure_new_id (GST_QUARK (EVENT_LATENCY),
1123 GST_QUARK (LATENCY), G_TYPE_UINT64, latency, NULL);
1124 event = gst_event_new_custom (GST_EVENT_LATENCY, structure);
1130 * gst_event_parse_latency:
1131 * @event: The event to query
1132 * @latency: (out): A pointer to store the latency in.
1134 * Get the latency in the latency event.
1139 gst_event_parse_latency (GstEvent * event, GstClockTime * latency)
1141 g_return_if_fail (GST_IS_EVENT (event));
1142 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_LATENCY);
1146 g_value_get_uint64 (gst_structure_id_get_value (GST_EVENT_STRUCTURE
1147 (event), GST_QUARK (LATENCY)));
1151 * gst_event_new_step:
1152 * @format: the format of @amount
1153 * @amount: the amount of data to step
1154 * @rate: the step rate
1155 * @flush: flushing steps
1156 * @intermediate: intermediate steps
1158 * Create a new step event. The purpose of the step event is to instruct a sink
1159 * to skip @amount (expressed in @format) of media. It can be used to implement
1160 * stepping through the video frame by frame or for doing fast trick modes.
1162 * A rate of <= 0.0 is not allowed. Pause the pipeline, for the effect of rate
1163 * = 0.0 or first reverse the direction of playback using a seek event to get
1164 * the same effect as rate < 0.0.
1166 * The @flush flag will clear any pending data in the pipeline before starting
1167 * the step operation.
1169 * The @intermediate flag instructs the pipeline that this step operation is
1170 * part of a larger step operation.
1172 * Returns: (transfer full): a new #GstEvent
1177 gst_event_new_step (GstFormat format, guint64 amount, gdouble rate,
1178 gboolean flush, gboolean intermediate)
1181 GstStructure *structure;
1183 g_return_val_if_fail (rate > 0.0, NULL);
1185 GST_CAT_INFO (GST_CAT_EVENT, "creating step event");
1187 structure = gst_structure_new_id (GST_QUARK (EVENT_STEP),
1188 GST_QUARK (FORMAT), GST_TYPE_FORMAT, format,
1189 GST_QUARK (AMOUNT), G_TYPE_UINT64, amount,
1190 GST_QUARK (RATE), G_TYPE_DOUBLE, rate,
1191 GST_QUARK (FLUSH), G_TYPE_BOOLEAN, flush,
1192 GST_QUARK (INTERMEDIATE), G_TYPE_BOOLEAN, intermediate, NULL);
1193 event = gst_event_new_custom (GST_EVENT_STEP, structure);
1199 * gst_event_parse_step:
1200 * @event: The event to query
1201 * @format: (out) (allow-none): a pointer to store the format in
1202 * @amount: (out) (allow-none): a pointer to store the amount in
1203 * @rate: (out) (allow-none): a pointer to store the rate in
1204 * @flush: (out) (allow-none): a pointer to store the flush boolean in
1205 * @intermediate: (out) (allow-none): a pointer to store the intermediate
1208 * Parse the step event.
1213 gst_event_parse_step (GstEvent * event, GstFormat * format, guint64 * amount,
1214 gdouble * rate, gboolean * flush, gboolean * intermediate)
1216 const GstStructure *structure;
1218 g_return_if_fail (GST_IS_EVENT (event));
1219 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_STEP);
1221 structure = GST_EVENT_STRUCTURE (event);
1224 (GstFormat) g_value_get_enum (gst_structure_id_get_value (structure,
1225 GST_QUARK (FORMAT)));
1227 *amount = g_value_get_uint64 (gst_structure_id_get_value (structure,
1228 GST_QUARK (AMOUNT)));
1230 *rate = g_value_get_double (gst_structure_id_get_value (structure,
1233 *flush = g_value_get_boolean (gst_structure_id_get_value (structure,
1234 GST_QUARK (FLUSH)));
1236 *intermediate = g_value_get_boolean (gst_structure_id_get_value (structure,
1237 GST_QUARK (INTERMEDIATE)));
1241 * gst_event_new_reconfigure:
1243 * Create a new reconfigure event. The purpose of the reconfingure event is
1244 * to travel upstream and make elements renegotiate their caps or reconfigure
1245 * their buffer pools. This is useful when changing properties on elements
1246 * or changing the topology of the pipeline.
1248 * Returns: (transfer full): a new #GstEvent
1253 gst_event_new_reconfigure (void)
1257 GST_CAT_INFO (GST_CAT_EVENT, "creating reconfigure event");
1259 event = gst_event_new_custom (GST_EVENT_RECONFIGURE, NULL);
1265 * gst_event_new_sink_message:
1266 * @msg: (transfer none): the #GstMessage to be posted
1268 * Create a new sink-message event. The purpose of the sink-message event is
1269 * to instruct a sink to post the message contained in the event synchronized
1272 * Returns: (transfer full): a new #GstEvent
1276 /* FIXME 0.11: take ownership of msg for consistency? */
1278 gst_event_new_sink_message (GstMessage * msg)
1281 GstStructure *structure;
1283 g_return_val_if_fail (msg != NULL, NULL);
1285 GST_CAT_INFO (GST_CAT_EVENT, "creating sink-message event");
1287 structure = gst_structure_new_id (GST_QUARK (EVENT_SINK_MESSAGE),
1288 GST_QUARK (MESSAGE), GST_TYPE_MESSAGE, msg, NULL);
1289 event = gst_event_new_custom (GST_EVENT_SINK_MESSAGE, structure);
1295 * gst_event_parse_sink_message:
1296 * @event: The event to query
1297 * @msg: (out) (transfer full): a pointer to store the #GstMessage in.
1299 * Parse the sink-message event. Unref @msg after usage.
1304 gst_event_parse_sink_message (GstEvent * event, GstMessage ** msg)
1306 const GstStructure *structure;
1308 g_return_if_fail (GST_IS_EVENT (event));
1309 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SINK_MESSAGE);
1311 structure = GST_EVENT_STRUCTURE (event);
1314 GST_MESSAGE (g_value_dup_boxed (gst_structure_id_get_value
1315 (structure, GST_QUARK (MESSAGE))));