2 * Copyright (C) 2005 Wim Taymans <wim@fluendo.com>
4 * gstsegment.c: GstSegment subsystem
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Library General Public
8 * License as published by the Free Software Foundation; either
9 * version 2 of the License, or (at your option) any later version.
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Library General Public License for more details.
16 * You should have received a copy of the GNU Library General Public
17 * License along with this library; if not, write to the
18 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 * Boston, MA 02111-1307, USA.
22 #include "gst_private.h"
27 #include "gstsegment.h"
31 * @short_description: Structure describing the configured region of interest
33 * @see_also: #GstEvent
35 * This helper structure holds the relevant values for tracking the region of
36 * interest in a media file, called a segment.
38 * The structure can be used for two purposes:
40 * <listitem><para>performing seeks (handling seek events)</para></listitem>
41 * <listitem><para>tracking playback regions (handling newsegment events)</para></listitem>
44 * The segment is usually configured by the application with a seek event which
45 * is propagated upstream and eventually handled by an element that performs the seek.
47 * The configured segment is then propagated back downstream with a newsegment event.
48 * This information is then used to clip media to the segment boundaries.
50 * A segment structure is initialized with gst_segment_init(), which takes a #GstFormat
51 * that will be used as the format of the segment values. The segment will be configured
52 * with a start value of 0 and a stop/duration of -1, which is undefined. The default
53 * rate and applied_rate is 1.0.
55 * The public duration field contains the duration of the segment. When using
56 * the segment for seeking, the start and time members should normally be left
57 * to their default 0 value. The stop position is left to -1 unless explicitly
58 * configured to a different value after a seek event.
60 * The current position in the segment should be set by changing the position
61 * member in the structure.
63 * For elements that perform seeks, the current segment should be updated with the
64 * gst_segment_do_seek() and the values from the seek event. This method will update
65 * all the segment fields. The position field will contain the new playback position.
66 * If the start_type was different from GST_SEEK_TYPE_NONE, playback continues from
67 * the position position, possibly with updated flags or rate.
69 * For elements that want to use #GstSegment to track the playback region,
70 * update the segment fields with the information from the newsegment event.
71 * The gst_segment_clip() method can be used to check and clip
72 * the media data to the segment boundaries.
74 * For elements that want to synchronize to the pipeline clock, gst_segment_to_running_time()
75 * can be used to convert a timestamp to a value that can be used to synchronize
76 * to the clock. This function takes into account the base as well as
77 * any rate or applied_rate conversions.
79 * For elements that need to perform operations on media data in stream_time,
80 * gst_segment_to_stream_time() can be used to convert a timestamp and the segment
81 * info to stream time (which is always between 0 and the duration of the stream).
83 * Last reviewed on 2012-03-29 (0.11.3)
88 * @segment: (transfer none): a #GstSegment
90 * Create a copy of given @segment.
92 * Free-function: gst_segment_free
94 * Returns: (transfer full): a new #GstSegment, free with gst_segment_free().
97 gst_segment_copy (const GstSegment * segment)
99 GstSegment *result = NULL;
102 result = (GstSegment *) g_slice_copy (sizeof (GstSegment), segment);
108 * gst_segment_copy_into:
109 * @src: (transfer none): a #GstSegment
110 * @dest: (transfer none): a #GstSegment
112 * Copy the contents of @src into @dest.
115 gst_segment_copy_into (const GstSegment * src, GstSegment * dest)
117 memcpy (dest, src, sizeof (GstSegment));
120 G_DEFINE_BOXED_TYPE (GstSegment, gst_segment,
121 (GBoxedCopyFunc) gst_segment_copy, (GBoxedFreeFunc) gst_segment_free);
126 * Allocate a new #GstSegment structure and initialize it using
127 * gst_segment_init().
129 * Free-function: gst_segment_free
131 * Returns: (transfer full): a new #GstSegment, free with gst_segment_free().
134 gst_segment_new (void)
138 result = g_slice_new0 (GstSegment);
139 gst_segment_init (result, GST_FORMAT_UNDEFINED);
146 * @segment: (in) (transfer full): a #GstSegment
148 * Free the allocated segment @segment.
151 gst_segment_free (GstSegment * segment)
153 g_slice_free (GstSegment, segment);
158 * @segment: a #GstSegment structure.
159 * @format: the format of the segment.
161 * The start/position fields are set to 0 and the stop/duration
162 * fields are set to -1 (unknown). The default rate of 1.0 and no
165 * Initialize @segment to its default values.
168 gst_segment_init (GstSegment * segment, GstFormat format)
170 g_return_if_fail (segment != NULL);
172 segment->flags = GST_SEGMENT_FLAG_NONE;
174 segment->applied_rate = 1.0;
175 segment->format = format;
181 segment->position = 0;
182 segment->duration = -1;
186 * gst_segment_do_seek:
187 * @segment: a #GstSegment structure.
188 * @rate: the rate of the segment.
189 * @format: the format of the segment.
190 * @flags: the segment flags for the segment
191 * @start_type: the seek method
192 * @start: the seek start value
193 * @stop_type: the seek method
194 * @stop: the seek stop value
195 * @update: boolean holding whether position was updated.
197 * Update the segment structure with the field values of a seek event (see
198 * gst_event_new_seek()).
200 * After calling this method, the segment field position and time will
201 * contain the requested new position in the segment. The new requested
202 * position in the segment depends on @rate and @start_type and @stop_type.
204 * For positive @rate, the new position in the segment is the new @segment
205 * start field when it was updated with a @start_type different from
206 * #GST_SEEK_TYPE_NONE. If no update was performed on @segment start position
207 * (#GST_SEEK_TYPE_NONE), @start is ignored and @segment position is
210 * For negative @rate, the new position in the segment is the new @segment
211 * stop field when it was updated with a @stop_type different from
212 * #GST_SEEK_TYPE_NONE. If no stop was previously configured in the segment, the
213 * duration of the segment will be used to update the stop position.
214 * If no update was performed on @segment stop position (#GST_SEEK_TYPE_NONE),
215 * @stop is ignored and @segment position is unmodified.
217 * The applied rate of the segment will be set to 1.0 by default.
218 * If the caller can apply a rate change, it should update @segment
219 * rate and applied_rate after calling this function.
221 * @update will be set to TRUE if a seek should be performed to the segment
222 * position field. This field can be FALSE if, for example, only the @rate
223 * has been changed but not the playback position.
225 * Returns: %TRUE if the seek could be performed.
228 gst_segment_do_seek (GstSegment * segment, gdouble rate,
229 GstFormat format, GstSeekFlags flags,
230 GstSeekType start_type, guint64 start,
231 GstSeekType stop_type, guint64 stop, gboolean * update)
233 gboolean update_stop, update_start;
234 guint64 position, base;
236 g_return_val_if_fail (rate != 0.0, FALSE);
237 g_return_val_if_fail (segment != NULL, FALSE);
238 g_return_val_if_fail (segment->format == format, FALSE);
240 update_start = update_stop = TRUE;
242 position = segment->position;
244 /* segment->start is never invalid */
245 switch (start_type) {
246 case GST_SEEK_TYPE_NONE:
247 /* no update to segment, take previous start */
248 start = segment->start;
249 update_start = FALSE;
251 case GST_SEEK_TYPE_SET:
252 /* start holds desired position, map -1 to the start */
256 case GST_SEEK_TYPE_END:
257 if (segment->duration != -1) {
258 /* add start to total length */
259 start = segment->duration + start;
261 /* no update if duration unknown */
262 start = segment->start;
263 update_start = FALSE;
267 /* bring in sane range */
268 if (segment->duration != -1)
269 start = MIN (start, segment->duration);
271 start = MAX (start, 0);
273 /* stop can be -1 if we have not configured a stop. */
275 case GST_SEEK_TYPE_NONE:
276 stop = segment->stop;
279 case GST_SEEK_TYPE_SET:
280 /* stop holds required value */
282 case GST_SEEK_TYPE_END:
283 if (segment->duration != -1) {
284 stop = segment->duration + stop;
286 stop = segment->stop;
292 /* if we have a valid stop time, make sure it is clipped */
294 if (segment->duration != -1)
295 stop = CLAMP (stop, 0, segment->duration);
297 stop = MAX (stop, 0);
300 /* we can't have stop before start */
303 g_return_val_if_fail (start <= stop, FALSE);
308 if (flags & GST_SEEK_FLAG_FLUSH) {
309 /* flush resets the running_time */
312 /* remember the elapsed time */
313 base = gst_segment_to_running_time (segment, format, position);
316 if (update_start && rate > 0.0) {
319 if (update_stop && rate < 0.0) {
323 if (segment->duration != -1)
324 position = segment->duration;
330 /* set update arg to reflect update of position */
332 *update = position != segment->position;
334 /* update new values */
335 /* be explicit about our GstSeekFlag -> GstSegmentFlag conversion */
336 segment->flags = GST_SEGMENT_FLAG_NONE;
337 if ((flags & GST_SEEK_FLAG_FLUSH) != 0)
338 segment->flags |= GST_SEGMENT_FLAG_RESET;
339 if ((flags & GST_SEEK_FLAG_SKIP) != 0)
340 segment->flags |= GST_SEGMENT_FLAG_SKIP;
341 if ((flags & GST_SEEK_FLAG_SEGMENT) != 0)
342 segment->flags |= GST_SEGMENT_FLAG_SEGMENT;
344 segment->rate = rate;
345 segment->applied_rate = 1.0;
347 segment->base = base;
349 segment->offset = position - start;
352 segment->offset = stop - position;
353 else if (segment->duration != -1)
354 segment->offset = segment->duration - position;
359 segment->start = start;
360 segment->stop = stop;
361 segment->time = start;
362 segment->position = position;
368 * gst_segment_to_stream_time:
369 * @segment: a #GstSegment structure.
370 * @format: the format of the segment.
371 * @position: the position in the segment
373 * Translate @position to stream time using the currently configured
374 * segment. The @position value must be between @segment start and
377 * This function is typically used by elements that need to operate on
378 * the stream time of the buffers it receives, such as effect plugins.
379 * In those use cases, @position is typically the buffer timestamp or
380 * clock time that one wants to convert to the stream time.
381 * The stream time is always between 0 and the total duration of the
384 * Returns: the position in stream_time or -1 when an invalid position
388 gst_segment_to_stream_time (const GstSegment * segment, GstFormat format,
391 guint64 result, start, stop, time;
392 gdouble abs_applied_rate;
394 /* format does not matter for -1 */
395 if (G_UNLIKELY (position == -1))
398 g_return_val_if_fail (segment != NULL, -1);
399 g_return_val_if_fail (segment->format == format, -1);
401 stop = segment->stop;
403 /* outside of the segment boundary stop */
404 if (G_UNLIKELY (stop != -1 && position > stop))
407 start = segment->start;
409 /* before the segment boundary */
410 if (G_UNLIKELY (position < start))
413 time = segment->time;
415 /* time must be known */
416 if (G_UNLIKELY (time == -1))
419 /* bring to uncorrected position in segment */
420 result = position - start;
422 abs_applied_rate = ABS (segment->applied_rate);
424 /* correct for applied rate if needed */
425 if (G_UNLIKELY (abs_applied_rate != 1.0))
426 result *= abs_applied_rate;
428 /* add or subtract from segment time based on applied rate */
429 if (G_LIKELY (segment->applied_rate > 0.0)) {
430 /* correct for segment time */
433 /* correct for segment time, clamp at 0. Streams with a negative
434 * applied_rate have timestamps between start and stop, as usual, but have
435 * the time member starting high and going backwards. */
436 if (G_LIKELY (time > result))
437 result = time - result;
446 * gst_segment_to_running_time:
447 * @segment: a #GstSegment structure.
448 * @format: the format of the segment.
449 * @position: the position in the segment
451 * Translate @position to the total running time using the currently configured
452 * segment. Position is a value between @segment start and stop time.
454 * This function is typically used by elements that need to synchronize to the
455 * global clock in a pipeline. The runnning time is a constantly increasing value
456 * starting from 0. When gst_segment_init() is called, this value will reset to
459 * This function returns -1 if the position is outside of @segment start and stop.
461 * Returns: the position as the total running time or -1 when an invalid position
465 gst_segment_to_running_time (const GstSegment * segment, GstFormat format,
472 if (G_UNLIKELY (position == -1))
475 g_return_val_if_fail (segment != NULL, -1);
476 g_return_val_if_fail (segment->format == format, -1);
478 start = segment->start;
480 if (segment->rate > 0.0)
481 start += segment->offset;
483 /* before the segment boundary */
484 if (G_UNLIKELY (position < start))
487 stop = segment->stop;
489 if (G_LIKELY (segment->rate > 0.0)) {
490 /* outside of the segment boundary stop */
491 if (G_UNLIKELY (stop != -1 && position > stop))
494 /* bring to uncorrected position in segment */
495 result = position - start;
497 /* cannot continue if no stop position set or outside of
499 if (G_UNLIKELY (stop == -1))
502 stop -= segment->offset;
503 if (G_UNLIKELY (position > stop))
506 /* bring to uncorrected position in segment */
507 result = stop - position;
510 /* scale based on the rate, avoid division by and conversion to
511 * float when not needed */
512 abs_rate = ABS (segment->rate);
513 if (G_UNLIKELY (abs_rate != 1.0))
516 /* correct for base of the segment */
517 result += segment->base;
524 * @segment: a #GstSegment structure.
525 * @format: the format of the segment.
526 * @start: the start position in the segment
527 * @stop: the stop position in the segment
528 * @clip_start: (out) (allow-none): the clipped start position in the segment
529 * @clip_stop: (out) (allow-none): the clipped stop position in the segment
531 * Clip the given @start and @stop values to the segment boundaries given
532 * in @segment. @start and @stop are compared and clipped to @segment
533 * start and stop values.
535 * If the function returns FALSE, @start and @stop are known to fall
536 * outside of @segment and @clip_start and @clip_stop are not updated.
538 * When the function returns TRUE, @clip_start and @clip_stop will be
539 * updated. If @clip_start or @clip_stop are different from @start or @stop
540 * respectively, the region fell partially in the segment.
542 * Note that when @stop is -1, @clip_stop will be set to the end of the
543 * segment. Depending on the use case, this may or may not be what you want.
545 * Returns: TRUE if the given @start and @stop times fall partially or
546 * completely in @segment, FALSE if the values are completely outside
550 gst_segment_clip (const GstSegment * segment, GstFormat format, guint64 start,
551 guint64 stop, guint64 * clip_start, guint64 * clip_stop)
553 g_return_val_if_fail (segment != NULL, FALSE);
554 g_return_val_if_fail (segment->format == format, FALSE);
556 /* if we have a stop position and a valid start and start is bigger,
557 * we're outside of the segment */
558 if (G_UNLIKELY (segment->stop != -1 && start != -1 && start >= segment->stop))
561 /* if a stop position is given and is before the segment start,
562 * we're outside of the segment. Special case is were start
563 * and stop are equal to the segment start. In that case we
564 * are inside the segment. */
565 if (G_UNLIKELY (stop != -1 && (stop < segment->start || (start != stop
566 && stop == segment->start))))
573 *clip_start = MAX (start, segment->start);
578 *clip_stop = segment->stop;
579 else if (segment->stop == -1)
582 *clip_stop = MIN (stop, segment->stop);
589 * gst_segment_to_position:
590 * @segment: a #GstSegment structure.
591 * @format: the format of the segment.
592 * @running_time: the running_time in the segment
594 * Convert @running_time into a position in the segment so that
595 * gst_segment_to_running_time() with that position returns @running_time.
597 * Returns: the position in the segment for @running_time. This function returns
598 * -1 when @running_time is -1 or when it is not inside @segment.
601 gst_segment_to_position (const GstSegment * segment, GstFormat format,
602 guint64 running_time)
605 guint64 start, stop, base;
608 if (G_UNLIKELY (running_time == -1))
611 g_return_val_if_fail (segment != NULL, -1);
612 g_return_val_if_fail (segment->format == format, FALSE);
614 base = segment->base;
616 /* this running_time was for a previous segment */
617 if (running_time < base)
620 /* start by subtracting the base time */
621 result = running_time - base;
623 /* move into the segment at the right rate */
624 abs_rate = ABS (segment->rate);
625 if (G_UNLIKELY (abs_rate != 1.0))
626 result = ceil (result * abs_rate);
628 start = segment->start;
629 stop = segment->stop;
631 if (G_LIKELY (segment->rate > 0.0)) {
632 /* bring to corrected position in segment */
635 /* outside of the segment boundary stop */
636 if (G_UNLIKELY (stop != -1 && result > stop))
639 /* cannot continue if no stop position set or outside of
641 if (G_UNLIKELY (stop == -1 || result + start > stop))
644 /* bring to corrected position in segment */
645 result = stop - result;
652 * gst_segment_set_running_time:
653 * @segment: a #GstSegment structure.
654 * @format: the format of the segment.
655 * @running_time: the running_time in the segment
657 * Adjust the start/stop and base values of @segment such that the next valid
658 * buffer will be one with @running_time.
660 * Returns: %TRUE if the segment could be updated successfully. If %FALSE is
661 * returned, @running_time is -1 or not in @segment.
664 gst_segment_set_running_time (GstSegment * segment, GstFormat format,
665 guint64 running_time)
670 /* start by bringing the running_time into the segment position */
671 position = gst_segment_to_position (segment, format, running_time);
673 /* we must have a valid position now */
674 if (G_UNLIKELY (position == -1))
677 start = segment->start;
678 stop = segment->stop;
680 if (G_LIKELY (segment->rate > 0.0)) {
681 /* update the start and time values */
684 /* reverse, update stop */
687 /* and base time is exactly the running time */
688 segment->time = gst_segment_to_stream_time (segment, format, start);
689 segment->start = start;
690 segment->stop = stop;
691 segment->base = running_time;