2 * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
3 * 2000,2004 Wim Taymans <wim@fluendo.com>
5 * gstelement.h: Header for GstElement
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Library General Public
9 * License as published by the Free Software Foundation; either
10 * version 2 of the License, or (at your option) any later version.
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Library General Public License for more details.
17 * You should have received a copy of the GNU Library General Public
18 * License along with this library; if not, write to the
19 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
20 * Boston, MA 02110-1301, USA.
24 #ifndef __GST_ELEMENT_H__
25 #define __GST_ELEMENT_H__
27 /* gstelement.h and gstelementfactory.h include eachother */
28 typedef struct _GstElement GstElement;
29 typedef struct _GstElementClass GstElementClass;
31 /* gstmessage.h needs State */
34 * @GST_STATE_VOID_PENDING: no pending state.
35 * @GST_STATE_NULL : the NULL state or initial state of an element.
36 * @GST_STATE_READY : the element is ready to go to PAUSED.
37 * @GST_STATE_PAUSED : the element is PAUSED, it is ready to accept and
38 * process data. Sink elements however only accept one
39 * buffer and then block.
40 * @GST_STATE_PLAYING : the element is PLAYING, the #GstClock is running and
41 * the data is flowing.
43 * The possible states an element can be in. States can be changed using
44 * gst_element_set_state() and checked using gst_element_get_state().
47 GST_STATE_VOID_PENDING = 0,
55 #include <gst/gstconfig.h>
56 #include <gst/gstobject.h>
57 #include <gst/gstpad.h>
58 #include <gst/gstbus.h>
59 #include <gst/gstclock.h>
60 #include <gst/gstelementfactory.h>
61 #include <gst/gstplugin.h>
62 #include <gst/gstpluginfeature.h>
63 #include <gst/gstiterator.h>
64 #include <gst/gstmessage.h>
65 #include <gst/gstquery.h>
66 #include <gst/gsttaglist.h>
70 #define GST_TYPE_ELEMENT (gst_element_get_type ())
71 #define GST_IS_ELEMENT(obj) (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GST_TYPE_ELEMENT))
72 #define GST_IS_ELEMENT_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GST_TYPE_ELEMENT))
73 #define GST_ELEMENT_GET_CLASS(obj) (G_TYPE_INSTANCE_GET_CLASS ((obj), GST_TYPE_ELEMENT, GstElementClass))
74 #define GST_ELEMENT(obj) (G_TYPE_CHECK_INSTANCE_CAST ((obj), GST_TYPE_ELEMENT, GstElement))
75 #define GST_ELEMENT_CLASS(klass) (G_TYPE_CHECK_CLASS_CAST ((klass), GST_TYPE_ELEMENT, GstElementClass))
76 #define GST_ELEMENT_CAST(obj) ((GstElement*)(obj))
79 * GstStateChangeReturn:
80 * @GST_STATE_CHANGE_FAILURE : the state change failed
81 * @GST_STATE_CHANGE_SUCCESS : the state change succeeded
82 * @GST_STATE_CHANGE_ASYNC : the state change will happen asynchronously
83 * @GST_STATE_CHANGE_NO_PREROLL: the state change succeeded but the element
84 * cannot produce data in %GST_STATE_PAUSED.
85 * This typically happens with live sources.
87 * The possible return values from a state change function such as
88 * gst_element_set_state(). Only @GST_STATE_CHANGE_FAILURE is a real failure.
91 GST_STATE_CHANGE_FAILURE = 0,
92 GST_STATE_CHANGE_SUCCESS = 1,
93 GST_STATE_CHANGE_ASYNC = 2,
94 GST_STATE_CHANGE_NO_PREROLL = 3
95 } GstStateChangeReturn;
97 /* NOTE: this probably should be done with an #ifdef to decide
98 * whether to safe-cast or to just do the non-checking cast.
103 * @elem: a #GstElement to return state for.
105 * This macro returns the current #GstState of the element.
107 #define GST_STATE(elem) (GST_ELEMENT_CAST(elem)->current_state)
111 * @elem: a #GstElement to return the next state for.
113 * This macro returns the next #GstState of the element.
115 #define GST_STATE_NEXT(elem) (GST_ELEMENT_CAST(elem)->next_state)
119 * @elem: a #GstElement to return the pending state for.
121 * This macro returns the currently pending #GstState of the element.
123 #define GST_STATE_PENDING(elem) (GST_ELEMENT_CAST(elem)->pending_state)
127 * @elem: a #GstElement to return the target state for.
129 * This macro returns the target #GstState of the element.
131 #define GST_STATE_TARGET(elem) (GST_ELEMENT_CAST(elem)->target_state)
135 * @elem: a #GstElement to return the last state result for.
137 * This macro returns the last #GstStateChangeReturn value.
139 #define GST_STATE_RETURN(elem) (GST_ELEMENT_CAST(elem)->last_return)
141 #define __GST_SIGN(val) ((val) < 0 ? -1 : ((val) > 0 ? 1 : 0))
143 * GST_STATE_GET_NEXT:
144 * @cur: A starting #GstState
145 * @pending: A target #GstState
147 * Given a current state @cur and a target state @pending, calculate the next (intermediate)
150 #define GST_STATE_GET_NEXT(cur,pending) ((GstState)((cur) + __GST_SIGN ((gint)(pending) - (gint)(cur))))
152 * GST_STATE_TRANSITION:
153 * @cur: A current state
154 * @next: A next state
156 * Given a current state @cur and a next state @next, calculate the associated
157 * #GstStateChange transition.
159 #define GST_STATE_TRANSITION(cur,next) ((GstStateChange)(((cur)<<3)|(next)))
161 * GST_STATE_TRANSITION_CURRENT:
162 * @trans: A #GstStateChange
164 * Given a state transition @trans, extract the current #GstState.
166 #define GST_STATE_TRANSITION_CURRENT(trans) ((GstState)((trans)>>3))
168 * GST_STATE_TRANSITION_NEXT:
169 * @trans: A #GstStateChange
171 * Given a state transition @trans, extract the next #GstState.
173 #define GST_STATE_TRANSITION_NEXT(trans) ((GstState)((trans)&0x7))
177 * @GST_STATE_CHANGE_NULL_TO_READY : state change from NULL to READY.
180 * The element must check if the resources it needs are available. Device
181 * sinks and -sources typically try to probe the device to constrain their
185 * The element opens the device (in case feature need to be probed).
188 * @GST_STATE_CHANGE_READY_TO_PAUSED : state change from READY to PAUSED.
191 * The element pads are activated in order to receive data in PAUSED.
192 * Streaming threads are started.
195 * Some elements might need to return %GST_STATE_CHANGE_ASYNC and complete
196 * the state change when they have enough information. It is a requirement
197 * for sinks to return %GST_STATE_CHANGE_ASYNC and complete the state change
198 * when they receive the first buffer or %GST_EVENT_EOS (preroll).
199 * Sinks also block the dataflow when in PAUSED.
202 * A pipeline resets the running_time to 0.
205 * Live sources return %GST_STATE_CHANGE_NO_PREROLL and don't generate data.
208 * @GST_STATE_CHANGE_PAUSED_TO_PLAYING: state change from PAUSED to PLAYING.
211 * Most elements ignore this state change.
214 * The pipeline selects a #GstClock and distributes this to all the children
215 * before setting them to PLAYING. This means that it is only allowed to
216 * synchronize on the #GstClock in the PLAYING state.
219 * The pipeline uses the #GstClock and the running_time to calculate the
220 * base_time. The base_time is distributed to all children when performing
224 * Sink elements stop blocking on the preroll buffer or event and start
225 * rendering the data.
228 * Sinks can post %GST_MESSAGE_EOS in the PLAYING state. It is not allowed
229 * to post %GST_MESSAGE_EOS when not in the PLAYING state.
232 * While streaming in PAUSED or PLAYING elements can create and remove
236 * Live sources start generating data and return %GST_STATE_CHANGE_SUCCESS.
239 * @GST_STATE_CHANGE_PLAYING_TO_PAUSED: state change from PLAYING to PAUSED.
242 * Most elements ignore this state change.
245 * The pipeline calculates the running_time based on the last selected
246 * #GstClock and the base_time. It stores this information to continue
247 * playback when going back to the PLAYING state.
250 * Sinks unblock any #GstClock wait calls.
253 * When a sink does not have a pending buffer to play, it returns
254 * %GST_STATE_CHANGE_ASYNC from this state change and completes the state
255 * change when it receives a new buffer or an %GST_EVENT_EOS.
258 * Any queued %GST_MESSAGE_EOS items are removed since they will be reposted
259 * when going back to the PLAYING state. The EOS messages are queued in
260 * #GstBin containers.
263 * Live sources stop generating data and return %GST_STATE_CHANGE_NO_PREROLL.
266 * @GST_STATE_CHANGE_PAUSED_TO_READY : state change from PAUSED to READY.
269 * Sinks unblock any waits in the preroll.
272 * Elements unblock any waits on devices
275 * Chain or get_range functions return %GST_FLOW_FLUSHING.
278 * The element pads are deactivated so that streaming becomes impossible and
279 * all streaming threads are stopped.
282 * The sink forgets all negotiated formats
285 * Elements remove all sometimes pads
288 * @GST_STATE_CHANGE_READY_TO_NULL : state change from READY to NULL.
291 * Elements close devices
294 * Elements reset any internal state.
298 * These are the different state changes an element goes through.
299 * %GST_STATE_NULL ⇒ %GST_STATE_PLAYING is called an upwards state change
300 * and %GST_STATE_PLAYING ⇒ %GST_STATE_NULL a downwards state change.
302 typedef enum /*< flags=0 >*/
304 GST_STATE_CHANGE_NULL_TO_READY = (GST_STATE_NULL<<3) | GST_STATE_READY,
305 GST_STATE_CHANGE_READY_TO_PAUSED = (GST_STATE_READY<<3) | GST_STATE_PAUSED,
306 GST_STATE_CHANGE_PAUSED_TO_PLAYING = (GST_STATE_PAUSED<<3) | GST_STATE_PLAYING,
307 GST_STATE_CHANGE_PLAYING_TO_PAUSED = (GST_STATE_PLAYING<<3) | GST_STATE_PAUSED,
308 GST_STATE_CHANGE_PAUSED_TO_READY = (GST_STATE_PAUSED<<3) | GST_STATE_READY,
309 GST_STATE_CHANGE_READY_TO_NULL = (GST_STATE_READY<<3) | GST_STATE_NULL
314 * @GST_ELEMENT_FLAG_LOCKED_STATE: ignore state changes from parent
315 * @GST_ELEMENT_FLAG_SINK: the element is a sink
316 * @GST_ELEMENT_FLAG_SOURCE: the element is a source.
317 * @GST_ELEMENT_FLAG_PROVIDE_CLOCK: the element can provide a clock
318 * @GST_ELEMENT_FLAG_REQUIRE_CLOCK: the element requires a clock
319 * @GST_ELEMENT_FLAG_INDEXABLE: the element can use an index
320 * @GST_ELEMENT_FLAG_LAST: offset to define more flags
322 * The standard flags that an element may have.
326 GST_ELEMENT_FLAG_LOCKED_STATE = (GST_OBJECT_FLAG_LAST << 0),
327 GST_ELEMENT_FLAG_SINK = (GST_OBJECT_FLAG_LAST << 1),
328 GST_ELEMENT_FLAG_SOURCE = (GST_OBJECT_FLAG_LAST << 2),
329 GST_ELEMENT_FLAG_PROVIDE_CLOCK = (GST_OBJECT_FLAG_LAST << 3),
330 GST_ELEMENT_FLAG_REQUIRE_CLOCK = (GST_OBJECT_FLAG_LAST << 4),
331 GST_ELEMENT_FLAG_INDEXABLE = (GST_OBJECT_FLAG_LAST << 5),
333 GST_ELEMENT_FLAG_LAST = (GST_OBJECT_FLAG_LAST << 10)
337 * GST_ELEMENT_IS_LOCKED_STATE:
338 * @elem: A #GstElement to query
340 * Check if the element is in the locked state and therefore will ignore state
341 * changes from its parent object.
343 #define GST_ELEMENT_IS_LOCKED_STATE(elem) (GST_OBJECT_FLAG_IS_SET(elem,GST_ELEMENT_FLAG_LOCKED_STATE))
347 * @elem: A #GstElement to query
349 * Gets the name of this element. This is not thread-safe by default
350 * (i.e. you will have to make sure the object lock is taken yourself).
351 * If in doubt use gst_element_get_name() instead.
353 #define GST_ELEMENT_NAME(elem) (GST_OBJECT_NAME(elem))
356 * GST_ELEMENT_PARENT:
357 * @elem: A #GstElement to query
359 * Get the parent object of this element. This is not thread-safe by default
360 * (i.e. you will have to make sure the object lock is taken yourself).
361 * If in doubt use gst_object_get_parent() instead.
363 #define GST_ELEMENT_PARENT(elem) (GST_ELEMENT_CAST(GST_OBJECT_PARENT(elem)))
367 * @elem: A #GstElement to query
369 * Get the message bus of this element. This is not thread-safe by default
370 * (i.e. you will have to make sure the object lock is taken yourself).
371 * If in doubt use gst_element_get_bus() instead.
373 #define GST_ELEMENT_BUS(elem) (GST_ELEMENT_CAST(elem)->bus)
377 * @elem: A #GstElement to query
379 * Get the clock of this element.This is not thread-safe by default
380 * (i.e. you will have to make sure it is safe yourself).
381 * If in doubt use gst_element_get_clock() instead.
383 #define GST_ELEMENT_CLOCK(elem) (GST_ELEMENT_CAST(elem)->clock)
387 * @elem: A #GstElement to query
389 * Get the pads of this elements.
391 #define GST_ELEMENT_PADS(elem) (GST_ELEMENT_CAST(elem)->pads)
394 * GST_ELEMENT_START_TIME:
395 * @elem: a #GstElement to return the start time for.
397 * This macro returns the start_time of the @elem. The start_time is the
398 * running_time of the pipeline when the element went to PAUSED.
400 #define GST_ELEMENT_START_TIME(elem) (GST_ELEMENT_CAST(elem)->start_time)
402 GstStructure *gst_make_element_message_details (const char *name, ...);
403 #define GST_ELEMENT_MESSAGE_MAKE_DETAILS(args) gst_make_element_message_details args
406 * GST_ELEMENT_ERROR_WITH_DETAILS:
407 * @el: the element that generates the error
408 * @domain: like CORE, LIBRARY, RESOURCE or STREAM (see #gstreamer-GstGError)
409 * @code: error code defined for that domain (see #gstreamer-GstGError)
410 * @text: the message to display (format string and args enclosed in
412 * @debug: debugging information for the message (format string and args
413 enclosed in parentheses)
414 * @args optional name, type, value triplets, which will be stored
415 * in the associated GstStructure. NULL terminator required.
416 * Must be enclosed within parentheses.
418 * Utility function that elements can use in case they encountered a fatal
419 * data processing error. The pipeline will post an error message and the
420 * application will be requested to stop further media processing.
424 #define GST_ELEMENT_ERROR_WITH_DETAILS(el,domain,code,text,debug,args) \
426 gchar *__txt = _gst_element_error_printf text; \
427 gchar *__dbg = _gst_element_error_printf debug; \
429 GST_WARNING_OBJECT (el, "error: %s", __txt); \
431 GST_WARNING_OBJECT (el, "error: %s", __dbg); \
432 gst_element_message_full_with_details (GST_ELEMENT(el), \
433 GST_MESSAGE_ERROR, GST_ ## domain ## _ERROR, \
434 GST_ ## domain ## _ERROR_ ## code, __txt, __dbg, __FILE__, \
435 GST_FUNCTION, __LINE__, GST_ELEMENT_MESSAGE_MAKE_DETAILS(args)); \
440 * @el: the element that generates the error
441 * @domain: like CORE, LIBRARY, RESOURCE or STREAM (see #gstreamer-GstGError)
442 * @code: error code defined for that domain (see #gstreamer-GstGError)
443 * @text: the message to display (format string and args enclosed in
445 * @debug: debugging information for the message (format string and args
446 enclosed in parentheses)
448 * Utility function that elements can use in case they encountered a fatal
449 * data processing error. The pipeline will post an error message and the
450 * application will be requested to stop further media processing.
452 #define GST_ELEMENT_ERROR(el,domain,code,text,debug) \
454 gchar *__txt = _gst_element_error_printf text; \
455 gchar *__dbg = _gst_element_error_printf debug; \
457 GST_WARNING_OBJECT (el, "error: %s", __txt); \
459 GST_WARNING_OBJECT (el, "error: %s", __dbg); \
460 gst_element_message_full (GST_ELEMENT(el), \
461 GST_MESSAGE_ERROR, GST_ ## domain ## _ERROR, \
462 GST_ ## domain ## _ERROR_ ## code, __txt, __dbg, __FILE__, \
463 GST_FUNCTION, __LINE__); \
467 * GST_ELEMENT_WARNING_WITH_DETAILS:
468 * @el: the element that generates the warning
469 * @domain: like CORE, LIBRARY, RESOURCE or STREAM (see #gstreamer-GstGError)
470 * @code: error code defined for that domain (see #gstreamer-GstGError)
471 * @text: the message to display (format string and args enclosed in
473 * @debug: debugging information for the message (format string and args
474 enclosed in parentheses)
475 * @args optional name, type, value triplets, which will be stored
476 * in the associated GstStructure. NULL terminator required.
477 * Must be enclosed within parentheses.
479 * Utility function that elements can use in case they encountered a non-fatal
480 * data processing problem. The pipeline will post a warning message and the
481 * application will be informed.
485 #define GST_ELEMENT_WARNING_WITH_DETAILS(el, domain, code, text, debug, args)\
487 gchar *__txt = _gst_element_error_printf text; \
488 gchar *__dbg = _gst_element_error_printf debug; \
490 GST_WARNING_OBJECT (el, "warning: %s", __txt); \
492 GST_WARNING_OBJECT (el, "warning: %s", __dbg); \
493 gst_element_message_full_with_details (GST_ELEMENT(el), \
494 GST_MESSAGE_WARNING, GST_ ## domain ## _ERROR, \
495 GST_ ## domain ## _ERROR_ ## code, __txt, __dbg, __FILE__, \
496 GST_FUNCTION, __LINE__, GST_ELEMENT_MESSAGE_MAKE_DETAILS(args)); \
500 * GST_ELEMENT_WARNING:
501 * @el: the element that generates the warning
502 * @domain: like CORE, LIBRARY, RESOURCE or STREAM (see #gstreamer-GstGError)
503 * @code: error code defined for that domain (see #gstreamer-GstGError)
504 * @text: the message to display (format string and args enclosed in
506 * @debug: debugging information for the message (format string and args
507 enclosed in parentheses)
509 * Utility function that elements can use in case they encountered a non-fatal
510 * data processing problem. The pipeline will post a warning message and the
511 * application will be informed.
513 #define GST_ELEMENT_WARNING(el, domain, code, text, debug) \
515 gchar *__txt = _gst_element_error_printf text; \
516 gchar *__dbg = _gst_element_error_printf debug; \
518 GST_WARNING_OBJECT (el, "warning: %s", __txt); \
520 GST_WARNING_OBJECT (el, "warning: %s", __dbg); \
521 gst_element_message_full (GST_ELEMENT(el), \
522 GST_MESSAGE_WARNING, GST_ ## domain ## _ERROR, \
523 GST_ ## domain ## _ERROR_ ## code, __txt, __dbg, __FILE__, \
524 GST_FUNCTION, __LINE__); \
528 * GST_ELEMENT_INFO_WITH_DETAILS:
529 * @el: the element that generates the information
530 * @domain: like CORE, LIBRARY, RESOURCE or STREAM (see #gstreamer-GstGError)
531 * @code: error code defined for that domain (see #gstreamer-GstGError)
532 * @text: the message to display (format string and args enclosed in
534 * @debug: debugging information for the message (format string and args
535 enclosed in parentheses)
536 * @args optional name, type, value triplets, which will be stored
537 * in the associated GstStructure. NULL terminator required.
538 * Must be enclosed within parentheses.
540 * Utility function that elements can use in case they want to inform
541 * the application of something noteworthy that is not an error.
542 * The pipeline will post a info message and the
543 * application will be informed.
544 * Optional name, type, value triplets may be supplied, and will be stored
545 * in the associated GstStructure. NULL terminator required.
549 #define GST_ELEMENT_INFO_WITH_DETAILS(el, domain, code, text, debug, args) \
551 gchar *__txt = _gst_element_error_printf text; \
552 gchar *__dbg = _gst_element_error_printf debug; \
554 GST_INFO_OBJECT (el, "info: %s", __txt); \
556 GST_INFO_OBJECT (el, "info: %s", __dbg); \
557 gst_element_message_full_with_details (GST_ELEMENT(el), \
558 GST_MESSAGE_INFO, GST_ ## domain ## _ERROR, \
559 GST_ ## domain ## _ERROR_ ## code, __txt, __dbg, __FILE__, \
560 GST_FUNCTION, __LINE__, GST_ELEMENT_MESSAGE_MAKE_DETAILS(args)); \
565 * @el: the element that generates the information
566 * @domain: like CORE, LIBRARY, RESOURCE or STREAM (see #gstreamer-GstGError)
567 * @code: error code defined for that domain (see #gstreamer-GstGError)
568 * @text: the message to display (format string and args enclosed in
570 * @debug: debugging information for the message (format string and args
571 enclosed in parentheses)
573 * Utility function that elements can use in case they want to inform
574 * the application of something noteworthy that is not an error.
575 * The pipeline will post a info message and the
576 * application will be informed.
578 #define GST_ELEMENT_INFO(el, domain, code, text, debug) \
580 gchar *__txt = _gst_element_error_printf text; \
581 gchar *__dbg = _gst_element_error_printf debug; \
583 GST_INFO_OBJECT (el, "info: %s", __txt); \
585 GST_INFO_OBJECT (el, "info: %s", __dbg); \
586 gst_element_message_full (GST_ELEMENT(el), \
587 GST_MESSAGE_INFO, GST_ ## domain ## _ERROR, \
588 GST_ ## domain ## _ERROR_ ## code, __txt, __dbg, __FILE__, \
589 GST_FUNCTION, __LINE__); \
592 /* the state change mutexes and conds */
594 * GST_STATE_GET_LOCK:
595 * @elem: a #GstElement
597 * Get a reference to the state lock of @elem.
598 * This lock is used by the core. It is taken while getting or setting
599 * the state, during state changes, and while finalizing.
601 #define GST_STATE_GET_LOCK(elem) (&(GST_ELEMENT_CAST(elem)->state_lock))
603 * GST_STATE_GET_COND:
604 * @elem: a #GstElement
606 * Get the conditional used to signal the completion of a state change.
608 #define GST_STATE_GET_COND(elem) (&GST_ELEMENT_CAST(elem)->state_cond)
610 #define GST_STATE_LOCK(elem) g_rec_mutex_lock(GST_STATE_GET_LOCK(elem))
611 #define GST_STATE_TRYLOCK(elem) g_rec_mutex_trylock(GST_STATE_GET_LOCK(elem))
612 #define GST_STATE_UNLOCK(elem) g_rec_mutex_unlock(GST_STATE_GET_LOCK(elem))
613 #define GST_STATE_WAIT(elem) g_cond_wait (GST_STATE_GET_COND (elem), \
614 GST_OBJECT_GET_LOCK (elem))
615 #define GST_STATE_WAIT_UNTIL(elem, end_time) g_cond_wait_until (GST_STATE_GET_COND (elem), \
616 GST_OBJECT_GET_LOCK (elem), end_time)
617 #define GST_STATE_SIGNAL(elem) g_cond_signal (GST_STATE_GET_COND (elem));
618 #define GST_STATE_BROADCAST(elem) g_cond_broadcast (GST_STATE_GET_COND (elem));
622 * @state_lock: Used to serialize execution of gst_element_set_state()
623 * @state_cond: Used to signal completion of a state change
624 * @state_cookie: Used to detect concurrent execution of
625 * gst_element_set_state() and gst_element_get_state()
626 * @target_state: the target state of an element as set by the application
627 * @current_state: the current state of an element
628 * @next_state: the next state of an element, can be #GST_STATE_VOID_PENDING if
629 * the element is in the correct state.
630 * @pending_state: the final state the element should go to, can be
631 * #GST_STATE_VOID_PENDING if the element is in the correct state
632 * @last_return: the last return value of an element state change
633 * @bus: the bus of the element. This bus is provided to the element by the
634 * parent element or the application. A #GstPipeline has a bus of its own.
635 * @clock: the clock of the element. This clock is usually provided to the
636 * element by the toplevel #GstPipeline.
637 * @base_time: the time of the clock right before the element is set to
638 * PLAYING. Subtracting @base_time from the current clock time in the PLAYING
639 * state will yield the running_time against the clock.
640 * @start_time: the running_time of the last PAUSED state
641 * @numpads: number of pads of the element, includes both source and sink pads.
642 * @pads: (element-type Gst.Pad): list of pads
643 * @numsrcpads: number of source pads of the element.
644 * @srcpads: (element-type Gst.Pad): list of source pads
645 * @numsinkpads: number of sink pads of the element.
646 * @sinkpads: (element-type Gst.Pad): list of sink pads
647 * @pads_cookie: updated whenever the a pad is added or removed
649 * GStreamer element abstract base class.
655 /*< public >*/ /* with LOCK */
656 GRecMutex state_lock;
660 guint32 state_cookie;
661 GstState target_state;
662 GstState current_state;
664 GstState pending_state;
665 GstStateChangeReturn last_return;
669 /* allocated clock */
671 GstClockTimeDiff base_time; /* NULL/READY: 0 - PAUSED: current time - PLAYING: difference to clock */
672 GstClockTime start_time;
674 /* element pads, these lists can only be iterated while holding
675 * the LOCK or checking the cookie after each LOCK. */
684 /* with object LOCK */
688 gpointer _gst_reserved[GST_PADDING-1];
693 * @parent_class: the parent class structure
694 * @metadata: metadata for elements of this class
695 * @elementfactory: the #GstElementFactory that creates these elements
696 * @padtemplates: a #GList of #GstPadTemplate
697 * @numpadtemplates: the number of padtemplates
698 * @pad_templ_cookie: changed whenever the padtemplates change
699 * @request_new_pad: called when a new pad is requested
700 * @release_pad: called when a request pad is to be released
701 * @get_state: get the state of the element
702 * @set_state: set a new state on the element
703 * @change_state: called by @set_state to perform an incremental state change
704 * @set_bus: set a #GstBus on the element
705 * @provide_clock: gets the #GstClock provided by the element
706 * @set_clock: set the #GstClock on the element
707 * @send_event: send a #GstEvent to the element
708 * @query: perform a #GstQuery on the element
709 * @state_changed: called immediately after a new state was set.
710 * @post_message: called when a message is posted on the element. Chain up to
711 * the parent class' handler to have it posted on the bus.
712 * @set_context: set a #GstContext on the element
714 * GStreamer element class. Override the vmethods to implement the element
717 struct _GstElementClass
719 GstObjectClass parent_class;
722 /* the element metadata */
725 /* factory that the element was created from */
726 GstElementFactory *elementfactory;
728 /* templates for our pads */
730 gint numpadtemplates;
731 guint32 pad_templ_cookie;
734 /* signal callbacks */
735 void (*pad_added) (GstElement *element, GstPad *pad);
736 void (*pad_removed) (GstElement *element, GstPad *pad);
737 void (*no_more_pads) (GstElement *element);
740 /* virtual methods for subclasses */
742 /* request/release pads */
743 /* FIXME 2.0 harmonize naming with gst_element_request_pad */
744 GstPad* (*request_new_pad) (GstElement *element, GstPadTemplate *templ,
745 const gchar* name, const GstCaps *caps);
747 void (*release_pad) (GstElement *element, GstPad *pad);
750 GstStateChangeReturn (*get_state) (GstElement * element, GstState * state,
751 GstState * pending, GstClockTime timeout);
752 GstStateChangeReturn (*set_state) (GstElement *element, GstState state);
753 GstStateChangeReturn (*change_state) (GstElement *element, GstStateChange transition);
754 void (*state_changed) (GstElement *element, GstState oldstate,
755 GstState newstate, GstState pending);
758 void (*set_bus) (GstElement * element, GstBus * bus);
761 GstClock* (*provide_clock) (GstElement *element);
762 gboolean (*set_clock) (GstElement *element, GstClock *clock);
764 /* query functions */
765 gboolean (*send_event) (GstElement *element, GstEvent *event);
767 gboolean (*query) (GstElement *element, GstQuery *query);
769 gboolean (*post_message) (GstElement *element, GstMessage *message);
771 void (*set_context) (GstElement *element, GstContext *context);
774 gpointer _gst_reserved[GST_PADDING_LARGE-2];
777 /* element class pad templates */
778 void gst_element_class_add_pad_template (GstElementClass *klass, GstPadTemplate *templ);
780 void gst_element_class_add_static_pad_template (GstElementClass *klass, GstStaticPadTemplate *static_templ);
782 GstPadTemplate* gst_element_class_get_pad_template (GstElementClass *element_class, const gchar *name);
783 GList* gst_element_class_get_pad_template_list (GstElementClass *element_class);
785 /* element class meta data */
786 void gst_element_class_set_metadata (GstElementClass *klass,
787 const gchar *longname,
788 const gchar *classification,
789 const gchar *description,
790 const gchar *author);
791 void gst_element_class_set_static_metadata (GstElementClass *klass,
792 const gchar *longname,
793 const gchar *classification,
794 const gchar *description,
795 const gchar *author);
796 void gst_element_class_add_metadata (GstElementClass * klass,
797 const gchar * key, const gchar * value);
798 void gst_element_class_add_static_metadata (GstElementClass * klass,
799 const gchar * key, const gchar * value);
800 const gchar * gst_element_class_get_metadata (GstElementClass * klass,
804 /* element instance */
805 GType gst_element_get_type (void);
807 /* basic name and parentage stuff from GstObject */
810 * gst_element_get_name:
811 * @elem: a #GstElement to get the name of @elem.
813 * Returns a copy of the name of @elem.
814 * Caller should g_free() the return value after usage.
815 * For a nameless element, this returns %NULL, which you can safely g_free()
818 * Returns: (transfer full) (nullable): the name of @elem. g_free()
819 * after usage. MT safe.
822 #define gst_element_get_name(elem) gst_object_get_name(GST_OBJECT_CAST(elem))
825 * gst_element_set_name:
826 * @elem: a #GstElement to set the name of.
827 * @name: the new name
829 * Sets the name of the element, getting rid of the old name if there was one.
831 #define gst_element_set_name(elem,name) gst_object_set_name(GST_OBJECT_CAST(elem),name)
834 * gst_element_get_parent:
835 * @elem: a #GstElement to get the parent of.
837 * Get the parent of an element.
839 * Returns: (transfer full): the parent of an element.
841 #define gst_element_get_parent(elem) gst_object_get_parent(GST_OBJECT_CAST(elem))
844 * gst_element_set_parent:
845 * @elem: a #GstElement to set the parent of.
846 * @parent: the new parent #GstObject of the element.
848 * Sets the parent of an element.
850 #define gst_element_set_parent(elem,parent) gst_object_set_parent(GST_OBJECT_CAST(elem),parent)
853 GstClock* gst_element_provide_clock (GstElement *element);
854 GstClock* gst_element_get_clock (GstElement *element);
855 gboolean gst_element_set_clock (GstElement *element, GstClock *clock);
856 void gst_element_set_base_time (GstElement *element, GstClockTime time);
857 GstClockTime gst_element_get_base_time (GstElement *element);
858 void gst_element_set_start_time (GstElement *element, GstClockTime time);
859 GstClockTime gst_element_get_start_time (GstElement *element);
862 void gst_element_set_bus (GstElement * element, GstBus * bus);
863 GstBus * gst_element_get_bus (GstElement * element);
866 void gst_element_set_context (GstElement * element, GstContext * context);
867 GList * gst_element_get_contexts (GstElement * element);
868 GstContext * gst_element_get_context (GstElement * element, const gchar * context_type);
869 GstContext * gst_element_get_context_unlocked (GstElement * element, const gchar * context_type);
872 gboolean gst_element_add_pad (GstElement *element, GstPad *pad);
873 gboolean gst_element_remove_pad (GstElement *element, GstPad *pad);
874 void gst_element_no_more_pads (GstElement *element);
876 GstPad* gst_element_get_static_pad (GstElement *element, const gchar *name);
877 GstPad* gst_element_get_request_pad (GstElement *element, const gchar *name);
878 GstPad* gst_element_request_pad (GstElement *element, GstPadTemplate *templ,
879 const gchar * name, const GstCaps *caps);
880 void gst_element_release_request_pad (GstElement *element, GstPad *pad);
882 GstIterator * gst_element_iterate_pads (GstElement * element);
883 GstIterator * gst_element_iterate_src_pads (GstElement * element);
884 GstIterator * gst_element_iterate_sink_pads (GstElement * element);
886 /* event/query/format stuff */
887 gboolean gst_element_send_event (GstElement *element, GstEvent *event);
888 gboolean gst_element_seek (GstElement *element, gdouble rate,
889 GstFormat format, GstSeekFlags flags,
890 GstSeekType start_type, gint64 start,
891 GstSeekType stop_type, gint64 stop);
892 gboolean gst_element_query (GstElement *element, GstQuery *query);
895 gboolean gst_element_post_message (GstElement * element, GstMessage * message);
898 /* gcc versions < 3.3 warn about NULL being passed as format to printf */
899 #if (!defined(__GNUC__) || (__GNUC__ < 3) || (__GNUC__ == 3 && __GNUC_MINOR__ < 3))
900 gchar * _gst_element_error_printf (const gchar *format, ...);
902 gchar * _gst_element_error_printf (const gchar *format, ...) G_GNUC_PRINTF (1, 2);
904 void gst_element_message_full (GstElement * element, GstMessageType type,
905 GQuark domain, gint code, gchar * text,
906 gchar * debug, const gchar * file,
907 const gchar * function, gint line);
909 void gst_element_message_full_with_details (GstElement * element, GstMessageType type,
910 GQuark domain, gint code, gchar * text,
911 gchar * debug, const gchar * file,
912 const gchar * function, gint line,
913 GstStructure * structure);
915 /* state management */
916 gboolean gst_element_is_locked_state (GstElement *element);
917 gboolean gst_element_set_locked_state (GstElement *element, gboolean locked_state);
918 gboolean gst_element_sync_state_with_parent (GstElement *element);
920 GstStateChangeReturn gst_element_get_state (GstElement * element,
923 GstClockTime timeout);
924 GstStateChangeReturn gst_element_set_state (GstElement *element, GstState state);
926 void gst_element_abort_state (GstElement * element);
927 GstStateChangeReturn gst_element_change_state (GstElement * element,
928 GstStateChange transition);
929 GstStateChangeReturn gst_element_continue_state (GstElement * element,
930 GstStateChangeReturn ret);
931 void gst_element_lost_state (GstElement * element);
933 typedef void (*GstElementCallAsyncFunc) (GstElement * element,
936 void gst_element_call_async (GstElement * element,
937 GstElementCallAsyncFunc func, gpointer user_data,
938 GDestroyNotify destroy_notify);
940 /* factory management */
941 GstElementFactory* gst_element_get_factory (GstElement *element);
943 /* utility functions */
944 gulong gst_element_add_property_notify_watch (GstElement * element,
945 const gchar * property_name,
946 gboolean include_value);
948 gulong gst_element_add_property_deep_notify_watch (GstElement * element,
949 const gchar * property_name,
950 gboolean include_value);
952 void gst_element_remove_property_notify_watch (GstElement * element,
955 #ifdef G_DEFINE_AUTOPTR_CLEANUP_FUNC
956 G_DEFINE_AUTOPTR_CLEANUP_FUNC(GstElement, gst_object_unref)
961 #endif /* __GST_ELEMENT_H__ */