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 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_BOTH, "custom-both", 0},
126 {GST_EVENT_CUSTOM_BOTH_OOB, "custom-both-oob", 0},
132 _gst_event_initialize (void)
136 _gst_event_type = gst_mini_object_register ("GstEvent");
138 g_type_class_ref (gst_seek_flags_get_type ());
139 g_type_class_ref (gst_seek_type_get_type ());
141 for (i = 0; event_quarks[i].name; i++) {
142 event_quarks[i].quark = g_quark_from_static_string (event_quarks[i].name);
147 * gst_event_type_get_name:
148 * @type: the event type
150 * Get a printable name for the given event type. Do not modify or free.
152 * Returns: a reference to the static name of the event.
155 gst_event_type_get_name (GstEventType type)
159 for (i = 0; event_quarks[i].name; i++) {
160 if (type == event_quarks[i].type)
161 return event_quarks[i].name;
167 * gst_event_type_to_quark:
168 * @type: the event type
170 * Get the unique quark for the given event type.
172 * Returns: the quark associated with the event type
175 gst_event_type_to_quark (GstEventType type)
179 for (i = 0; event_quarks[i].name; i++) {
180 if (type == event_quarks[i].type)
181 return event_quarks[i].quark;
187 * gst_event_type_get_flags:
188 * @type: a #GstEventType
190 * Gets the #GstEventTypeFlags associated with @type.
192 * Returns: a #GstEventTypeFlags.
195 gst_event_type_get_flags (GstEventType type)
197 GstEventTypeFlags ret;
199 ret = type & ((1 << GST_EVENT_STICKY_SHIFT) - 1);
205 _gst_event_free (GstEvent * event)
209 g_return_if_fail (event != NULL);
210 g_return_if_fail (GST_IS_EVENT (event));
212 GST_CAT_LOG (GST_CAT_EVENT, "freeing event %p type %s", event,
213 GST_EVENT_TYPE_NAME (event));
215 s = GST_EVENT_STRUCTURE (event);
218 gst_structure_set_parent_refcount (s, NULL);
219 gst_structure_free (s);
222 g_slice_free1 (GST_MINI_OBJECT_SIZE (event), event);
225 static void gst_event_init (GstEventImpl * event, gsize size,
229 _gst_event_copy (GstEvent * event)
234 copy = g_slice_new0 (GstEventImpl);
236 gst_event_init (copy, sizeof (GstEventImpl), GST_EVENT_TYPE (event));
238 GST_EVENT_TIMESTAMP (copy) = GST_EVENT_TIMESTAMP (event);
239 GST_EVENT_SEQNUM (copy) = GST_EVENT_SEQNUM (event);
241 s = GST_EVENT_STRUCTURE (event);
243 GST_EVENT_STRUCTURE (copy) = gst_structure_copy (s);
244 gst_structure_set_parent_refcount (GST_EVENT_STRUCTURE (copy),
245 ©->event.mini_object.refcount);
247 return GST_EVENT_CAST (copy);
251 gst_event_init (GstEventImpl * event, gsize size, GstEventType type)
253 gst_mini_object_init (GST_MINI_OBJECT_CAST (event), _gst_event_type, size);
255 event->event.mini_object.copy = (GstMiniObjectCopyFunction) _gst_event_copy;
256 event->event.mini_object.free = (GstMiniObjectFreeFunction) _gst_event_free;
258 GST_EVENT_TYPE (event) = type;
259 GST_EVENT_TIMESTAMP (event) = GST_CLOCK_TIME_NONE;
260 GST_EVENT_SEQNUM (event) = gst_util_seqnum_next ();
264 gst_event_new (GstEventType type)
268 event = g_slice_new0 (GstEventImpl);
270 GST_CAT_DEBUG (GST_CAT_EVENT, "creating new event %p %s %d", event,
271 gst_event_type_get_name (type), type);
273 gst_event_init (event, sizeof (GstEventImpl), type);
275 return GST_EVENT_CAST (event);
279 * gst_event_new_custom:
280 * @type: The type of the new event
281 * @structure: (transfer full): the structure for the event. The event will
282 * take ownership of the structure.
284 * Create a new custom-typed event. This can be used for anything not
285 * handled by other event-specific functions to pass an event to another
288 * Make sure to allocate an event type with the #GST_EVENT_MAKE_TYPE macro,
289 * assigning a free number and filling in the correct direction and
290 * serialization flags.
292 * New custom events can also be created by subclassing the event type if
295 * Returns: (transfer full): the new custom event.
298 gst_event_new_custom (GstEventType type, GstStructure * structure)
302 /* structure must not have a parent */
303 event = gst_event_new (type);
305 if (!gst_structure_set_parent_refcount (structure,
306 &event->mini_object.refcount))
309 GST_EVENT_STRUCTURE (event) = structure;
316 gst_event_unref (event);
317 g_warning ("structure is already owned by another object");
323 * gst_event_get_structure:
324 * @event: The #GstEvent.
326 * Access the structure of the event.
328 * Returns: The structure of the event. The structure is still
329 * owned by the event, which means that you should not free it and
330 * that the pointer becomes invalid when you free the event.
335 gst_event_get_structure (GstEvent * event)
337 g_return_val_if_fail (GST_IS_EVENT (event), NULL);
339 return GST_EVENT_STRUCTURE (event);
343 * gst_event_writable_structure:
344 * @event: The #GstEvent.
346 * Get a writable version of the structure.
348 * Returns: The structure of the event. The structure is still
349 * owned by the event, which means that you should not free it and
350 * that the pointer becomes invalid when you free the event.
351 * This function checks if @event is writable and will never return NULL.
356 gst_event_writable_structure (GstEvent * event)
358 GstStructure *structure;
360 g_return_val_if_fail (GST_IS_EVENT (event), NULL);
361 g_return_val_if_fail (gst_event_is_writable (event), NULL);
363 structure = GST_EVENT_STRUCTURE (event);
365 if (structure == NULL) {
367 gst_structure_id_empty_new (gst_event_type_to_quark (GST_EVENT_TYPE
369 gst_structure_set_parent_refcount (structure, &event->mini_object.refcount);
370 GST_EVENT_STRUCTURE (event) = structure;
376 * gst_event_has_name:
377 * @event: The #GstEvent.
378 * @name: name to check
380 * Checks if @event has the given @name. This function is usually used to
381 * check the name of a custom event.
383 * Returns: %TRUE if @name matches the name of the event structure.
388 gst_event_has_name (GstEvent * event, const gchar * name)
390 g_return_val_if_fail (GST_IS_EVENT (event), FALSE);
392 if (GST_EVENT_STRUCTURE (event) == NULL)
395 return gst_structure_has_name (GST_EVENT_STRUCTURE (event), name);
399 * gst_event_get_seqnum:
400 * @event: A #GstEvent.
402 * Retrieve the sequence number of a event.
404 * Events have ever-incrementing sequence numbers, which may also be set
405 * explicitly via gst_event_set_seqnum(). Sequence numbers are typically used to
406 * indicate that a event corresponds to some other set of events or messages,
407 * for example an EOS event corresponding to a SEEK event. It is considered good
408 * practice to make this correspondence when possible, though it is not
411 * Note that events and messages share the same sequence number incrementor;
412 * two events or messages will never have the same sequence number unless
413 * that correspondence was made explicitly.
415 * Returns: The event's sequence number.
422 gst_event_get_seqnum (GstEvent * event)
424 g_return_val_if_fail (GST_IS_EVENT (event), -1);
426 return GST_EVENT_SEQNUM (event);
430 * gst_event_set_seqnum:
431 * @event: A #GstEvent.
432 * @seqnum: A sequence number.
434 * Set the sequence number of a event.
436 * This function might be called by the creator of a event to indicate that the
437 * event relates to other events or messages. See gst_event_get_seqnum() for
445 gst_event_set_seqnum (GstEvent * event, guint32 seqnum)
447 g_return_if_fail (GST_IS_EVENT (event));
449 GST_EVENT_SEQNUM (event) = seqnum;
452 /* FIXME 0.11: It would be nice to have flush events
453 * that don't reset the running time in the sinks
457 * gst_event_new_flush_start:
459 * Allocate a new flush start event. The flush start event can be sent
460 * upstream and downstream and travels out-of-bounds with the dataflow.
462 * It marks pads as being flushing and will make them return
463 * #GST_FLOW_WRONG_STATE when used for data flow with gst_pad_push(),
464 * gst_pad_chain(), gst_pad_alloc_buffer(), gst_pad_get_range() and
465 * gst_pad_pull_range(). Any event (except a #GST_EVENT_FLUSH_STOP) received
466 * on a flushing pad will return %FALSE immediately.
468 * Elements should unlock any blocking functions and exit their streaming
469 * functions as fast as possible when this event is received.
471 * This event is typically generated after a seek to flush out all queued data
472 * in the pipeline so that the new media is played as soon as possible.
474 * Returns: (transfer full): a new flush start event.
477 gst_event_new_flush_start (void)
479 return gst_event_new (GST_EVENT_FLUSH_START);
483 * gst_event_new_flush_stop:
484 * @reset_time: if time should be reset
486 * Allocate a new flush stop event. The flush stop event can be sent
487 * upstream and downstream and travels serialized with the dataflow.
488 * It is typically sent after sending a FLUSH_START event to make the
489 * pads accept data again.
491 * Elements can process this event synchronized with the dataflow since
492 * the preceeding FLUSH_START event stopped the dataflow.
494 * This event is typically generated to complete a seek and to resume
497 * Returns: (transfer full): a new flush stop event.
500 gst_event_new_flush_stop (gboolean reset_time)
504 GST_CAT_INFO (GST_CAT_EVENT, "creating flush stop %d", reset_time);
506 event = gst_event_new_custom (GST_EVENT_FLUSH_STOP,
507 gst_structure_id_new (GST_QUARK (EVENT_FLUSH_STOP),
508 GST_QUARK (RESET_TIME), G_TYPE_BOOLEAN, reset_time, NULL));
514 * gst_event_parse_flush_stop:
515 * @event: The event to parse
516 * @reset_time: (out): if time should be reset
518 * Parse the FLUSH_STOP event and retrieve the @reset_time member.
521 gst_event_parse_flush_stop (GstEvent * event, gboolean * reset_time)
523 GstStructure *structure;
525 g_return_if_fail (GST_IS_EVENT (event));
526 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_FLUSH_STOP);
528 structure = GST_EVENT_STRUCTURE (event);
529 if (G_LIKELY (reset_time))
531 g_value_get_boolean (gst_structure_id_get_value (structure,
532 GST_QUARK (RESET_TIME)));
538 * Create a new EOS event. The eos event can only travel downstream
539 * synchronized with the buffer flow. Elements that receive the EOS
540 * event on a pad can return #GST_FLOW_UNEXPECTED as a #GstFlowReturn
541 * when data after the EOS event arrives.
543 * The EOS event will travel down to the sink elements in the pipeline
544 * which will then post the #GST_MESSAGE_EOS on the bus after they have
545 * finished playing any buffered data.
547 * When all sinks have posted an EOS message, an EOS message is
548 * forwarded to the application.
550 * The EOS event itself will not cause any state transitions of the pipeline.
552 * Returns: (transfer full): the new EOS event.
555 gst_event_new_eos (void)
557 return gst_event_new (GST_EVENT_EOS);
561 * gst_event_new_caps:
564 * Create a new CAPS event for @caps. The caps event can only travel downstream
565 * synchronized with the buffer flow and contains the format of the buffers
566 * that will follow after the event.
568 * Returns: (transfer full): the new CAPS event.
571 gst_event_new_caps (GstCaps * caps)
575 g_return_val_if_fail (caps != NULL, NULL);
576 g_return_val_if_fail (gst_caps_is_fixed (caps), NULL);
578 GST_CAT_INFO (GST_CAT_EVENT, "creating caps event %" GST_PTR_FORMAT, caps);
580 event = gst_event_new_custom (GST_EVENT_CAPS,
581 gst_structure_id_new (GST_QUARK (EVENT_CAPS),
582 GST_QUARK (CAPS), GST_TYPE_CAPS, caps, NULL));
588 * gst_event_parse_caps:
589 * @event: The event to parse
590 * @caps: (out): A pointer to the caps
592 * Get the caps from @event. The caps remains valid as long as @event remains
596 gst_event_parse_caps (GstEvent * event, GstCaps ** caps)
598 GstStructure *structure;
600 g_return_if_fail (GST_IS_EVENT (event));
601 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_CAPS);
603 structure = GST_EVENT_STRUCTURE (event);
606 g_value_get_boxed (gst_structure_id_get_value (structure,
611 * gst_event_new_segment:
612 * @segment: a #GstSegment
614 * Create a new SEGMENT event for @segment. The segment event can only travel
615 * downstream synchronized with the buffer flow and contains timing information
616 * and playback properties for the buffers that will follow.
618 * The newsegment event marks the range of buffers to be processed. All
619 * data not within the segment range is not to be processed. This can be
620 * used intelligently by plugins to apply more efficient methods of skipping
621 * unneeded data. The valid range is expressed with the @start and @stop
624 * The time value of the segment is used in conjunction with the start
625 * value to convert the buffer timestamps into the stream time. This is
626 * usually done in sinks to report the current stream_time.
627 * @time represents the stream_time of a buffer carrying a timestamp of
628 * @start. @time cannot be -1.
630 * @start cannot be -1, @stop can be -1. If there
631 * is a valid @stop given, it must be greater or equal the @start, including
632 * when the indicated playback @rate is < 0.
634 * The @applied_rate value provides information about any rate adjustment that
635 * has already been made to the timestamps and content on the buffers of the
636 * stream. (@rate * @applied_rate) should always equal the rate that has been
637 * requested for playback. For example, if an element has an input segment
638 * with intended playback @rate of 2.0 and applied_rate of 1.0, it can adjust
639 * incoming timestamps and buffer content by half and output a newsegment event
640 * with @rate of 1.0 and @applied_rate of 2.0
642 * After a newsegment event, the buffer stream time is calculated with:
644 * time + (TIMESTAMP(buf) - start) * ABS (rate * applied_rate)
646 * Returns: (transfer full): the new SEGMENT event.
649 gst_event_new_segment (GstSegment * segment)
653 g_return_val_if_fail (segment != NULL, NULL);
655 GST_CAT_INFO (GST_CAT_EVENT, "creating segment event %" GST_SEGMENT_FORMAT,
658 event = gst_event_new_custom (GST_EVENT_SEGMENT,
659 gst_structure_id_new (GST_QUARK (EVENT_SEGMENT),
660 GST_QUARK (SEGMENT), GST_TYPE_SEGMENT, segment, NULL));
666 * gst_event_parse_segment:
667 * @event: The event to parse
668 * @segment: (out) (transfer none): a pointer to a #GstSegment
670 * Parses a segment @event and stores the result in the given @segment location.
671 * @segment remains valid only until the @event is freed. Don't modify the segment
672 * and make a copy if you want to modify it or store it for later use.
675 gst_event_parse_segment (GstEvent * event, const GstSegment ** segment)
677 GstStructure *structure;
679 g_return_if_fail (GST_IS_EVENT (event));
680 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SEGMENT);
683 structure = GST_EVENT_STRUCTURE (event);
684 *segment = g_value_get_boxed (gst_structure_id_get_value (structure,
685 GST_QUARK (SEGMENT)));
690 * gst_event_copy_segment:
691 * @event: The event to parse
692 * @segment: a pointer to a #GstSegment
694 * Parses a segment @event and copies the #GstSegment into the location
698 gst_event_copy_segment (GstEvent * event, GstSegment * segment)
700 const GstSegment *src;
702 g_return_if_fail (GST_IS_EVENT (event));
703 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SEGMENT);
706 gst_event_parse_segment (event, &src);
707 gst_segment_copy_into (src, segment);
713 * @taglist: (transfer full): metadata list. The event will take ownership
716 * Generates a metadata tag event from the given @taglist.
718 * Returns: (transfer full): a new #GstEvent
721 gst_event_new_tag (GstTagList * taglist)
723 g_return_val_if_fail (taglist != NULL, NULL);
725 return gst_event_new_custom (GST_EVENT_TAG, (GstStructure *) taglist);
729 * gst_event_parse_tag:
730 * @event: a tag event
731 * @taglist: (out) (transfer none): pointer to metadata list
733 * Parses a tag @event and stores the results in the given @taglist location.
734 * No reference to the taglist will be returned, it remains valid only until
735 * the @event is freed. Don't modify or free the taglist, make a copy if you
736 * want to modify it or store it for later use.
739 gst_event_parse_tag (GstEvent * event, GstTagList ** taglist)
741 g_return_if_fail (GST_IS_EVENT (event));
742 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_TAG);
745 *taglist = (GstTagList *) GST_EVENT_STRUCTURE (event);
748 /* buffersize event */
750 * gst_event_new_buffer_size:
751 * @format: buffer format
752 * @minsize: minimum buffer size
753 * @maxsize: maximum buffer size
754 * @async: thread behavior
756 * Create a new buffersize event. The event is sent downstream and notifies
757 * elements that they should provide a buffer of the specified dimensions.
759 * When the @async flag is set, a thread boundary is prefered.
761 * Returns: (transfer full): a new #GstEvent
764 gst_event_new_buffer_size (GstFormat format, gint64 minsize,
765 gint64 maxsize, gboolean async)
768 GstStructure *structure;
770 GST_CAT_INFO (GST_CAT_EVENT,
771 "creating buffersize format %s, minsize %" G_GINT64_FORMAT
772 ", maxsize %" G_GINT64_FORMAT ", async %d", gst_format_get_name (format),
773 minsize, maxsize, async);
775 structure = gst_structure_id_new (GST_QUARK (EVENT_BUFFER_SIZE),
776 GST_QUARK (FORMAT), GST_TYPE_FORMAT, format,
777 GST_QUARK (MINSIZE), G_TYPE_INT64, minsize,
778 GST_QUARK (MAXSIZE), G_TYPE_INT64, maxsize,
779 GST_QUARK (ASYNC), G_TYPE_BOOLEAN, async, NULL);
780 event = gst_event_new_custom (GST_EVENT_BUFFERSIZE, structure);
786 * gst_event_parse_buffer_size:
787 * @event: The event to query
788 * @format: (out): A pointer to store the format in
789 * @minsize: (out): A pointer to store the minsize in
790 * @maxsize: (out): A pointer to store the maxsize in
791 * @async: (out): A pointer to store the async-flag in
793 * Get the format, minsize, maxsize and async-flag in the buffersize event.
796 gst_event_parse_buffer_size (GstEvent * event, GstFormat * format,
797 gint64 * minsize, gint64 * maxsize, gboolean * async)
799 const GstStructure *structure;
801 g_return_if_fail (GST_IS_EVENT (event));
802 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_BUFFERSIZE);
804 structure = GST_EVENT_STRUCTURE (event);
806 *format = (GstFormat)
807 g_value_get_enum (gst_structure_id_get_value (structure,
808 GST_QUARK (FORMAT)));
811 g_value_get_int64 (gst_structure_id_get_value (structure,
812 GST_QUARK (MINSIZE)));
815 g_value_get_int64 (gst_structure_id_get_value (structure,
816 GST_QUARK (MAXSIZE)));
819 g_value_get_boolean (gst_structure_id_get_value (structure,
825 * @type: the QoS type
826 * @proportion: the proportion of the qos message
827 * @diff: The time difference of the last Clock sync
828 * @timestamp: The timestamp of the buffer
830 * Allocate a new qos event with the given values.
831 * The QOS event is generated in an element that wants an upstream
832 * element to either reduce or increase its rate because of
833 * high/low CPU load or other resource usage such as network performance or
834 * throttling. Typically sinks generate these events for each buffer
837 * @type indicates the reason for the QoS event. #GST_QOS_TYPE_OVERFLOW is
838 * used when a buffer arrived in time or when the sink cannot keep up with
839 * the upstream datarate. #GST_QOS_TYPE_UNDERFLOW is when the sink is not
840 * receiving buffers fast enough and thus has to drop late buffers.
841 * #GST_QOS_TYPE_THROTTLE is used when the datarate is artificially limited
842 * by the application, for example to reduce power consumption.
844 * @proportion indicates the real-time performance of the streaming in the
845 * element that generated the QoS event (usually the sink). The value is
846 * generally computed based on more long term statistics about the streams
847 * timestamps compared to the clock.
848 * A value < 1.0 indicates that the upstream element is producing data faster
849 * than real-time. A value > 1.0 indicates that the upstream element is not
850 * producing data fast enough. 1.0 is the ideal @proportion value. The
851 * proportion value can safely be used to lower or increase the quality of
854 * @diff is the difference against the clock in running time of the last
855 * buffer that caused the element to generate the QOS event. A negative value
856 * means that the buffer with @timestamp arrived in time. A positive value
857 * indicates how late the buffer with @timestamp was. When throttling is
858 * enabled, @diff will be set to the requested throttling interval.
860 * @timestamp is the timestamp of the last buffer that cause the element
861 * to generate the QOS event. It is expressed in running time and thus an ever
864 * The upstream element can use the @diff and @timestamp values to decide
865 * whether to process more buffers. For possitive @diff, all buffers with
866 * timestamp <= @timestamp + @diff will certainly arrive late in the sink
867 * as well. A (negative) @diff value so that @timestamp + @diff would yield a
868 * result smaller than 0 is not allowed.
870 * The application can use general event probes to intercept the QoS
871 * event and implement custom application specific QoS handling.
873 * Returns: (transfer full): a new QOS event.
876 gst_event_new_qos (GstQOSType type, gdouble proportion,
877 GstClockTimeDiff diff, GstClockTime timestamp)
880 GstStructure *structure;
882 /* diff must be positive or timestamp + diff must be positive */
883 g_return_val_if_fail (diff >= 0 || -diff <= timestamp, NULL);
885 GST_CAT_INFO (GST_CAT_EVENT,
886 "creating qos type %d, proportion %lf, diff %" G_GINT64_FORMAT
887 ", timestamp %" GST_TIME_FORMAT, type, proportion,
888 diff, GST_TIME_ARGS (timestamp));
890 structure = gst_structure_id_new (GST_QUARK (EVENT_QOS),
891 GST_QUARK (TYPE), GST_TYPE_QOS_TYPE, type,
892 GST_QUARK (PROPORTION), G_TYPE_DOUBLE, proportion,
893 GST_QUARK (DIFF), G_TYPE_INT64, diff,
894 GST_QUARK (TIMESTAMP), G_TYPE_UINT64, timestamp, NULL);
895 event = gst_event_new_custom (GST_EVENT_QOS, structure);
901 * gst_event_parse_qos:
902 * @event: The event to query
903 * @type: (out): A pointer to store the QoS type in
904 * @proportion: (out): A pointer to store the proportion in
905 * @diff: (out): A pointer to store the diff in
906 * @timestamp: (out): A pointer to store the timestamp in
908 * Get the type, proportion, diff and timestamp in the qos event. See
909 * gst_event_new_qos() for more information about the different QoS values.
912 gst_event_parse_qos (GstEvent * event, GstQOSType * type,
913 gdouble * proportion, GstClockTimeDiff * diff, GstClockTime * timestamp)
915 const GstStructure *structure;
917 g_return_if_fail (GST_IS_EVENT (event));
918 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_QOS);
920 structure = GST_EVENT_STRUCTURE (event);
923 g_value_get_enum (gst_structure_id_get_value (structure,
927 g_value_get_double (gst_structure_id_get_value (structure,
928 GST_QUARK (PROPORTION)));
931 g_value_get_int64 (gst_structure_id_get_value (structure,
935 g_value_get_uint64 (gst_structure_id_get_value (structure,
936 GST_QUARK (TIMESTAMP)));
940 * gst_event_new_seek:
941 * @rate: The new playback rate
942 * @format: The format of the seek values
943 * @flags: The optional seek flags
944 * @start_type: The type and flags for the new start position
945 * @start: The value of the new start position
946 * @stop_type: The type and flags for the new stop position
947 * @stop: The value of the new stop position
949 * Allocate a new seek event with the given parameters.
951 * The seek event configures playback of the pipeline between @start to @stop
952 * at the speed given in @rate, also called a playback segment.
953 * The @start and @stop values are expressed in @format.
955 * A @rate of 1.0 means normal playback rate, 2.0 means double speed.
956 * Negatives values means backwards playback. A value of 0.0 for the
957 * rate is not allowed and should be accomplished instead by PAUSING the
960 * A pipeline has a default playback segment configured with a start
961 * position of 0, a stop position of -1 and a rate of 1.0. The currently
962 * configured playback segment can be queried with #GST_QUERY_SEGMENT.
964 * @start_type and @stop_type specify how to adjust the currently configured
965 * start and stop fields in playback segment. Adjustments can be made relative
966 * or absolute to the last configured values. A type of #GST_SEEK_TYPE_NONE
967 * means that the position should not be updated.
969 * When the rate is positive and @start has been updated, playback will start
970 * from the newly configured start position.
972 * For negative rates, playback will start from the newly configured stop
973 * position (if any). If the stop position if updated, it must be different from
974 * -1 for negative rates.
976 * It is not possible to seek relative to the current playback position, to do
977 * this, PAUSE the pipeline, query the current playback position with
978 * #GST_QUERY_POSITION and update the playback segment current position with a
979 * #GST_SEEK_TYPE_SET to the desired position.
981 * Returns: (transfer full): a new seek event.
984 gst_event_new_seek (gdouble rate, GstFormat format, GstSeekFlags flags,
985 GstSeekType start_type, gint64 start, GstSeekType stop_type, gint64 stop)
988 GstStructure *structure;
990 g_return_val_if_fail (rate != 0.0, NULL);
992 if (format == GST_FORMAT_TIME) {
993 GST_CAT_INFO (GST_CAT_EVENT,
994 "creating seek rate %lf, format TIME, flags %d, "
995 "start_type %d, start %" GST_TIME_FORMAT ", "
996 "stop_type %d, stop %" GST_TIME_FORMAT,
997 rate, flags, start_type, GST_TIME_ARGS (start),
998 stop_type, GST_TIME_ARGS (stop));
1000 GST_CAT_INFO (GST_CAT_EVENT,
1001 "creating seek rate %lf, format %s, flags %d, "
1002 "start_type %d, start %" G_GINT64_FORMAT ", "
1003 "stop_type %d, stop %" G_GINT64_FORMAT,
1004 rate, gst_format_get_name (format), flags, start_type, start, stop_type,
1008 structure = gst_structure_id_new (GST_QUARK (EVENT_SEEK),
1009 GST_QUARK (RATE), G_TYPE_DOUBLE, rate,
1010 GST_QUARK (FORMAT), GST_TYPE_FORMAT, format,
1011 GST_QUARK (FLAGS), GST_TYPE_SEEK_FLAGS, flags,
1012 GST_QUARK (CUR_TYPE), GST_TYPE_SEEK_TYPE, start_type,
1013 GST_QUARK (CUR), G_TYPE_INT64, start,
1014 GST_QUARK (STOP_TYPE), GST_TYPE_SEEK_TYPE, stop_type,
1015 GST_QUARK (STOP), G_TYPE_INT64, stop, NULL);
1016 event = gst_event_new_custom (GST_EVENT_SEEK, structure);
1022 * gst_event_parse_seek:
1023 * @event: a seek event
1024 * @rate: (out): result location for the rate
1025 * @format: (out): result location for the stream format
1026 * @flags: (out): result location for the #GstSeekFlags
1027 * @start_type: (out): result location for the #GstSeekType of the start position
1028 * @start: (out): result location for the start postion expressed in @format
1029 * @stop_type: (out): result location for the #GstSeekType of the stop position
1030 * @stop: (out): result location for the stop postion expressed in @format
1032 * Parses a seek @event and stores the results in the given result locations.
1035 gst_event_parse_seek (GstEvent * event, gdouble * rate,
1036 GstFormat * format, GstSeekFlags * flags, GstSeekType * start_type,
1037 gint64 * start, GstSeekType * stop_type, gint64 * stop)
1039 const GstStructure *structure;
1041 g_return_if_fail (GST_IS_EVENT (event));
1042 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SEEK);
1044 structure = GST_EVENT_STRUCTURE (event);
1047 g_value_get_double (gst_structure_id_get_value (structure,
1050 *format = (GstFormat)
1051 g_value_get_enum (gst_structure_id_get_value (structure,
1052 GST_QUARK (FORMAT)));
1054 *flags = (GstSeekFlags)
1055 g_value_get_flags (gst_structure_id_get_value (structure,
1056 GST_QUARK (FLAGS)));
1058 *start_type = (GstSeekType)
1059 g_value_get_enum (gst_structure_id_get_value (structure,
1060 GST_QUARK (CUR_TYPE)));
1063 g_value_get_int64 (gst_structure_id_get_value (structure,
1066 *stop_type = (GstSeekType)
1067 g_value_get_enum (gst_structure_id_get_value (structure,
1068 GST_QUARK (STOP_TYPE)));
1071 g_value_get_int64 (gst_structure_id_get_value (structure,
1076 * gst_event_new_navigation:
1077 * @structure: (transfer full): description of the event. The event will take
1078 * ownership of the structure.
1080 * Create a new navigation event from the given description.
1082 * Returns: (transfer full): a new #GstEvent
1085 gst_event_new_navigation (GstStructure * structure)
1087 g_return_val_if_fail (structure != NULL, NULL);
1089 return gst_event_new_custom (GST_EVENT_NAVIGATION, structure);
1093 * gst_event_new_latency:
1094 * @latency: the new latency value
1096 * Create a new latency event. The event is sent upstream from the sinks and
1097 * notifies elements that they should add an additional @latency to the
1098 * running time before synchronising against the clock.
1100 * The latency is mostly used in live sinks and is always expressed in
1103 * Returns: (transfer full): a new #GstEvent
1108 gst_event_new_latency (GstClockTime latency)
1111 GstStructure *structure;
1113 GST_CAT_INFO (GST_CAT_EVENT,
1114 "creating latency event %" GST_TIME_FORMAT, GST_TIME_ARGS (latency));
1116 structure = gst_structure_id_new (GST_QUARK (EVENT_LATENCY),
1117 GST_QUARK (LATENCY), G_TYPE_UINT64, latency, NULL);
1118 event = gst_event_new_custom (GST_EVENT_LATENCY, structure);
1124 * gst_event_parse_latency:
1125 * @event: The event to query
1126 * @latency: (out): A pointer to store the latency in.
1128 * Get the latency in the latency event.
1133 gst_event_parse_latency (GstEvent * event, GstClockTime * latency)
1135 g_return_if_fail (GST_IS_EVENT (event));
1136 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_LATENCY);
1140 g_value_get_uint64 (gst_structure_id_get_value (GST_EVENT_STRUCTURE
1141 (event), GST_QUARK (LATENCY)));
1145 * gst_event_new_step:
1146 * @format: the format of @amount
1147 * @amount: the amount of data to step
1148 * @rate: the step rate
1149 * @flush: flushing steps
1150 * @intermediate: intermediate steps
1152 * Create a new step event. The purpose of the step event is to instruct a sink
1153 * to skip @amount (expressed in @format) of media. It can be used to implement
1154 * stepping through the video frame by frame or for doing fast trick modes.
1156 * A rate of <= 0.0 is not allowed, pause the pipeline or reverse the playback
1157 * direction of the pipeline to get the same effect.
1159 * The @flush flag will clear any pending data in the pipeline before starting
1160 * the step operation.
1162 * The @intermediate flag instructs the pipeline that this step operation is
1163 * part of a larger step operation.
1165 * Returns: (transfer full): a new #GstEvent
1170 gst_event_new_step (GstFormat format, guint64 amount, gdouble rate,
1171 gboolean flush, gboolean intermediate)
1174 GstStructure *structure;
1176 g_return_val_if_fail (rate > 0.0, NULL);
1178 GST_CAT_INFO (GST_CAT_EVENT, "creating step event");
1180 structure = gst_structure_id_new (GST_QUARK (EVENT_STEP),
1181 GST_QUARK (FORMAT), GST_TYPE_FORMAT, format,
1182 GST_QUARK (AMOUNT), G_TYPE_UINT64, amount,
1183 GST_QUARK (RATE), G_TYPE_DOUBLE, rate,
1184 GST_QUARK (FLUSH), G_TYPE_BOOLEAN, flush,
1185 GST_QUARK (INTERMEDIATE), G_TYPE_BOOLEAN, intermediate, NULL);
1186 event = gst_event_new_custom (GST_EVENT_STEP, structure);
1192 * gst_event_parse_step:
1193 * @event: The event to query
1194 * @format: (out) (allow-none): a pointer to store the format in
1195 * @amount: (out) (allow-none): a pointer to store the amount in
1196 * @rate: (out) (allow-none): a pointer to store the rate in
1197 * @flush: (out) (allow-none): a pointer to store the flush boolean in
1198 * @intermediate: (out) (allow-none): a pointer to store the intermediate
1201 * Parse the step event.
1206 gst_event_parse_step (GstEvent * event, GstFormat * format, guint64 * amount,
1207 gdouble * rate, gboolean * flush, gboolean * intermediate)
1209 const GstStructure *structure;
1211 g_return_if_fail (GST_IS_EVENT (event));
1212 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_STEP);
1214 structure = GST_EVENT_STRUCTURE (event);
1217 (GstFormat) g_value_get_enum (gst_structure_id_get_value (structure,
1218 GST_QUARK (FORMAT)));
1220 *amount = g_value_get_uint64 (gst_structure_id_get_value (structure,
1221 GST_QUARK (AMOUNT)));
1223 *rate = g_value_get_double (gst_structure_id_get_value (structure,
1226 *flush = g_value_get_boolean (gst_structure_id_get_value (structure,
1227 GST_QUARK (FLUSH)));
1229 *intermediate = g_value_get_boolean (gst_structure_id_get_value (structure,
1230 GST_QUARK (INTERMEDIATE)));
1234 * gst_event_new_reconfigure:
1236 * Create a new reconfigure event. The purpose of the reconfingure event is
1237 * to travel upstream and make elements renegotiate their caps or reconfigure
1238 * their buffer pools. This is useful when changing properties on elements
1239 * or changing the topology of the pipeline.
1241 * Returns: (transfer full): a new #GstEvent
1246 gst_event_new_reconfigure (void)
1250 GST_CAT_INFO (GST_CAT_EVENT, "creating reconfigure event");
1252 event = gst_event_new_custom (GST_EVENT_RECONFIGURE, NULL);
1258 * gst_event_new_sink_message:
1259 * @msg: (transfer none): the #GstMessage to be posted
1261 * Create a new sink-message event. The purpose of the sink-message event is
1262 * to instruct a sink to post the message contained in the event synchronized
1265 * Returns: (transfer full): a new #GstEvent
1269 /* FIXME 0.11: take ownership of msg for consistency? */
1271 gst_event_new_sink_message (GstMessage * msg)
1274 GstStructure *structure;
1276 g_return_val_if_fail (msg != NULL, NULL);
1278 GST_CAT_INFO (GST_CAT_EVENT, "creating sink-message event");
1280 structure = gst_structure_id_new (GST_QUARK (EVENT_SINK_MESSAGE),
1281 GST_QUARK (MESSAGE), GST_TYPE_MESSAGE, msg, NULL);
1282 event = gst_event_new_custom (GST_EVENT_SINK_MESSAGE, structure);
1288 * gst_event_parse_sink_message:
1289 * @event: The event to query
1290 * @msg: (out) (transfer full): a pointer to store the #GstMessage in.
1292 * Parse the sink-message event. Unref @msg after usage.
1297 gst_event_parse_sink_message (GstEvent * event, GstMessage ** msg)
1299 const GstStructure *structure;
1301 g_return_if_fail (GST_IS_EVENT (event));
1302 g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_SINK_MESSAGE);
1304 structure = GST_EVENT_STRUCTURE (event);
1307 GST_MESSAGE (g_value_dup_boxed (gst_structure_id_get_value
1308 (structure, GST_QUARK (MESSAGE))));