1 /* GStreamer
2 * Copyright (C) 2005 Wim Taymans <wim@fluendo.com>
3 *
4 * gstsegment.c: GstSegment subsystem
5 *
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.
10 *
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.
15 *
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.
20 */
22 #include "gst_private.h"
24 #include <math.h>
26 #include "gstutils.h"
27 #include "gstsegment.h"
29 /**
30 * SECTION:gstsegment
31 * @short_description: Structure describing the configured region of interest
32 * in a media file.
33 * @see_also: #GstEvent
34 *
35 * This helper structure holds the relevant values for tracking the region of
36 * interest in a media file, called a segment.
37 *
38 * The structure can be used for two purposes:
39 * <itemizedlist>
40 * <listitem><para>performing seeks (handling seek events)</para></listitem>
41 * <listitem><para>tracking playback regions (handling newsegment events)</para></listitem>
42 * </itemizedlist>
43 *
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.
46 *
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.
49 *
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.
54 *
55 * If the segment is used for managing seeks, the segment duration should be set with
56 * gst_segment_set_duration(). The public duration field contains the duration of the
57 * segment. When using the segment for seeking, the start and time members should
58 * normally be left to their default 0 value. The stop position is left to -1 unless
59 * explicitly configured to a different value after a seek event.
60 *
61 * The current position in the segment should be set with the gst_segment_set_last_stop().
62 * The public last_stop field contains the last set stop position in the segment.
63 *
64 * For elements that perform seeks, the current segment should be updated with the
65 * gst_segment_set_seek() and the values from the seek event. This method will update
66 * all the segment fields. The last_stop field will contain the new playback position.
67 * If the cur_type was different from GST_SEEK_TYPE_NONE, playback continues from
68 * the last_stop position, possibly with updated flags or rate.
69 *
70 * For elements that want to use #GstSegment to track the playback region, use
71 * gst_segment_set_newsegment() to update the segment fields with the information from
72 * the newsegment event. The gst_segment_clip() method can be used to check and clip
73 * the media data to the segment boundaries.
74 *
75 * For elements that want to synchronize to the pipeline clock, gst_segment_to_running_time()
76 * can be used to convert a timestamp to a value that can be used to synchronize
77 * to the clock. This function takes into account all accumulated segments as well as
78 * any rate or applied_rate conversions.
79 *
80 * For elements that need to perform operations on media data in stream_time,
81 * gst_segment_to_stream_time() can be used to convert a timestamp and the segment
82 * info to stream time (which is always between 0 and the duration of the stream).
83 *
84 * Last reviewed on 2007-05-17 (0.10.13)
85 */
87 /**
88 * gst_segment_copy:
89 * @segment: (transfer none): a #GstSegment
90 *
91 * Create a copy of given @segment.
92 *
93 * Free-function: gst_segment_free
94 *
95 * Returns: (transfer full): a new #GstSegment, free with gst_segment_free().
96 *
97 * Since: 0.10.20
98 */
99 GstSegment *
100 gst_segment_copy (GstSegment * segment)
101 {
102 GstSegment *result = NULL;
104 if (segment) {
105 result = (GstSegment *) g_slice_copy (sizeof (GstSegment), segment);
106 }
107 return result;
108 }
110 GType
111 gst_segment_get_type (void)
112 {
113 static GType gst_segment_type = 0;
115 if (G_UNLIKELY (gst_segment_type == 0)) {
116 gst_segment_type = g_boxed_type_register_static ("GstSegment",
117 (GBoxedCopyFunc) gst_segment_copy, (GBoxedFreeFunc) gst_segment_free);
118 }
120 return gst_segment_type;
121 }
123 /**
124 * gst_segment_new:
125 *
126 * Allocate a new #GstSegment structure and initialize it using
127 * gst_segment_init().
128 *
129 * Free-function: gst_segment_free
130 *
131 * Returns: (transfer full): a new #GstSegment, free with gst_segment_free().
132 */
133 GstSegment *
134 gst_segment_new (void)
135 {
136 GstSegment *result;
138 result = g_slice_new0 (GstSegment);
139 gst_segment_init (result, GST_FORMAT_UNDEFINED);
141 return result;
142 }
144 /**
145 * gst_segment_free:
146 * @segment: (in) (transfer full): a #GstSegment
147 *
148 * Free the allocated segment @segment.
149 */
150 void
151 gst_segment_free (GstSegment * segment)
152 {
153 g_slice_free (GstSegment, segment);
154 }
156 /**
157 * gst_segment_init:
158 * @segment: a #GstSegment structure.
159 * @format: the format of the segment.
160 *
161 * The start/last_stop positions are set to 0 and the stop/duration
162 * fields are set to -1 (unknown). The default rate of 1.0 and no
163 * flags are set.
164 *
165 * Initialize @segment to its default values.
166 */
167 void
168 gst_segment_init (GstSegment * segment, GstFormat format)
169 {
170 g_return_if_fail (segment != NULL);
172 segment->rate = 1.0;
173 segment->abs_rate = 1.0;
174 segment->applied_rate = 1.0;
175 segment->format = format;
176 segment->flags = GST_SEEK_FLAG_NONE;
177 segment->start = 0;
178 segment->stop = -1;
179 segment->time = 0;
180 segment->accum = 0;
181 segment->last_stop = 0;
182 segment->duration = -1;
183 }
185 /**
186 * gst_segment_set_duration:
187 * @segment: a #GstSegment structure.
188 * @format: the format of the segment.
189 * @duration: the duration of the segment info or -1 if unknown.
190 *
191 * Set the duration of the segment to @duration. This function is mainly
192 * used by elements that perform seeking and know the total duration of the
193 * segment.
194 *
195 * This field should be set to allow seeking requests relative to the
196 * duration.
197 */
198 void
199 gst_segment_set_duration (GstSegment * segment, GstFormat format,
200 gint64 duration)
201 {
202 g_return_if_fail (segment != NULL);
204 if (G_UNLIKELY (segment->format == GST_FORMAT_UNDEFINED))
205 segment->format = format;
206 else
207 g_return_if_fail (segment->format == format);
209 segment->duration = duration;
210 }
212 /**
213 * gst_segment_set_last_stop:
214 * @segment: a #GstSegment structure.
215 * @format: the format of the segment.
216 * @position: the position
217 *
218 * Set the last observed stop position in the segment to @position.
219 *
220 * This field should be set to allow seeking requests relative to the
221 * current playing position.
222 */
223 void
224 gst_segment_set_last_stop (GstSegment * segment, GstFormat format,
225 gint64 position)
226 {
227 g_return_if_fail (segment != NULL);
229 if (G_UNLIKELY (segment->format == GST_FORMAT_UNDEFINED))
230 segment->format = format;
231 else
232 g_return_if_fail (segment->format == format);
234 segment->last_stop = MAX (segment->start, position);
235 }
237 /**
238 * gst_segment_set_seek:
239 * @segment: a #GstSegment structure.
240 * @rate: the rate of the segment.
241 * @format: the format of the segment.
242 * @flags: the seek flags for the segment
243 * @start_type: the seek method
244 * @start: the seek start value
245 * @stop_type: the seek method
246 * @stop: the seek stop value
247 * @update: boolean holding whether last_stop was updated.
248 *
249 * Update the segment structure with the field values of a seek event (see
250 * gst_event_new_seek()).
251 *
252 * After calling this method, the segment field last_stop and time will
253 * contain the requested new position in the segment. The new requested
254 * position in the segment depends on @rate and @start_type and @stop_type.
255 *
256 * For positive @rate, the new position in the segment is the new @segment
257 * start field when it was updated with a @start_type different from
258 * #GST_SEEK_TYPE_NONE. If no update was performed on @segment start position
259 * (#GST_SEEK_TYPE_NONE), @start is ignored and @segment last_stop is
260 * unmodified.
261 *
262 * For negative @rate, the new position in the segment is the new @segment
263 * stop field when it was updated with a @stop_type different from
264 * #GST_SEEK_TYPE_NONE. If no stop was previously configured in the segment, the
265 * duration of the segment will be used to update the stop position.
266 * If no update was performed on @segment stop position (#GST_SEEK_TYPE_NONE),
267 * @stop is ignored and @segment last_stop is unmodified.
268 *
269 * The applied rate of the segment will be set to 1.0 by default.
270 * If the caller can apply a rate change, it should update @segment
271 * rate and applied_rate after calling this function.
272 *
273 * @update will be set to TRUE if a seek should be performed to the segment
274 * last_stop field. This field can be FALSE if, for example, only the @rate
275 * has been changed but not the playback position.
276 */
277 void
278 gst_segment_set_seek (GstSegment * segment, gdouble rate,
279 GstFormat format, GstSeekFlags flags,
280 GstSeekType start_type, gint64 start,
281 GstSeekType stop_type, gint64 stop, gboolean * update)
282 {
283 gboolean update_stop, update_start;
284 gint64 last_stop;
286 g_return_if_fail (rate != 0.0);
287 g_return_if_fail (segment != NULL);
289 if (G_UNLIKELY (segment->format == GST_FORMAT_UNDEFINED))
290 segment->format = format;
292 update_start = update_stop = TRUE;
294 /* segment->start is never invalid */
295 switch (start_type) {
296 case GST_SEEK_TYPE_NONE:
297 /* no update to segment, take previous start */
298 start = segment->start;
299 update_start = FALSE;
300 break;
301 case GST_SEEK_TYPE_SET:
302 /* start holds desired position, map -1 to the start */
303 if (start == -1)
304 start = 0;
305 /* start must be 0 or the formats must match */
306 g_return_if_fail (start == 0 || segment->format == format);
307 break;
308 case GST_SEEK_TYPE_CUR:
309 g_return_if_fail (start == 0 || segment->format == format);
310 /* add start to currently configured segment */
311 start = segment->start + start;
312 break;
313 case GST_SEEK_TYPE_END:
314 if (segment->duration != -1) {
315 g_return_if_fail (start == 0 || segment->format == format);
316 /* add start to total length */
317 start = segment->duration + start;
318 } else {
319 /* no update if duration unknown */
320 start = segment->start;
321 update_start = FALSE;
322 }
323 break;
324 }
325 /* bring in sane range */
326 if (segment->duration != -1)
327 start = CLAMP (start, 0, segment->duration);
328 else
329 start = MAX (start, 0);
331 /* stop can be -1 if we have not configured a stop. */
332 switch (stop_type) {
333 case GST_SEEK_TYPE_NONE:
334 stop = segment->stop;
335 update_stop = FALSE;
336 break;
337 case GST_SEEK_TYPE_SET:
338 /* stop holds required value, if it's not -1, it must be of the same
339 * format as the segment. */
340 g_return_if_fail (stop == -1 || segment->format == format);
341 break;
342 case GST_SEEK_TYPE_CUR:
343 if (segment->stop != -1) {
344 /* only add compatible formats or 0 */
345 g_return_if_fail (stop == 0 || segment->format == format);
346 stop = segment->stop + stop;
347 } else
348 stop = -1;
349 break;
350 case GST_SEEK_TYPE_END:
351 if (segment->duration != -1) {
352 /* only add compatible formats or 0 */
353 g_return_if_fail (stop == 0 || segment->format == format);
354 stop = segment->duration + stop;
355 } else {
356 stop = segment->stop;
357 update_stop = FALSE;
358 }
359 break;
360 }
362 /* if we have a valid stop time, make sure it is clipped */
363 if (stop != -1) {
364 if (segment->duration != -1)
365 stop = CLAMP (stop, 0, segment->duration);
366 else
367 stop = MAX (stop, 0);
368 }
370 /* we can't have stop before start */
371 if (stop != -1)
372 g_return_if_fail (start <= stop);
374 segment->rate = rate;
375 segment->abs_rate = ABS (rate);
376 segment->applied_rate = 1.0;
377 segment->flags = flags;
378 segment->start = start;
379 segment->stop = stop;
380 segment->time = start;
382 last_stop = segment->last_stop;
383 if (update_start && rate > 0.0) {
384 last_stop = start;
385 }
386 if (update_stop && rate < 0.0) {
387 if (stop != -1)
388 last_stop = stop;
389 else {
390 if (segment->duration != -1)
391 last_stop = segment->duration;
392 else
393 last_stop = 0;
394 }
395 }
396 /* set update arg to reflect update of last_stop */
397 if (update)
398 *update = last_stop != segment->last_stop;
400 /* update new position */
401 segment->last_stop = last_stop;
402 }
404 /**
405 * gst_segment_set_newsegment:
406 * @segment: a #GstSegment structure.
407 * @update: flag indicating a new segment is started or updated
408 * @rate: the rate of the segment.
409 * @format: the format of the segment.
410 * @start: the new start value
411 * @stop: the new stop value
412 * @time: the new stream time
413 *
414 * Update the segment structure with the field values of a new segment event and
415 * with a default applied_rate of 1.0.
416 *
417 * Since: 0.10.6
418 */
419 void
420 gst_segment_set_newsegment (GstSegment * segment, gboolean update, gdouble rate,
421 GstFormat format, gint64 start, gint64 stop, gint64 time)
422 {
423 gst_segment_set_newsegment_full (segment, update, rate, 1.0, format, start,
424 stop, time);
425 }
427 /**
428 * gst_segment_set_newsegment_full:
429 * @segment: a #GstSegment structure.
430 * @update: flag indicating a new segment is started or updated
431 * @rate: the rate of the segment.
432 * @applied_rate: the applied rate of the segment.
433 * @format: the format of the segment.
434 * @start: the new start value
435 * @stop: the new stop value
436 * @time: the new stream time
437 *
438 * Update the segment structure with the field values of a new segment event.
439 */
440 void
441 gst_segment_set_newsegment_full (GstSegment * segment, gboolean update,
442 gdouble rate, gdouble applied_rate, GstFormat format, gint64 start,
443 gint64 stop, gint64 time)
444 {
445 gint64 duration, last_stop;
447 g_return_if_fail (rate != 0.0);
448 g_return_if_fail (applied_rate != 0.0);
449 g_return_if_fail (segment != NULL);
451 GST_DEBUG ("configuring segment update %d, rate %lf, format %s, "
452 "start %" G_GINT64_FORMAT ", stop %" G_GINT64_FORMAT ", position %"
453 G_GINT64_FORMAT, update, rate, gst_format_get_name (format), start,
454 stop, time);
455 GST_DEBUG ("old segment was: %" GST_SEGMENT_FORMAT, segment);
457 if (G_UNLIKELY (segment->format == GST_FORMAT_UNDEFINED))
458 segment->format = format;
460 /* any other format with 0 also gives time 0, the other values are
461 * invalid in the format though. */
462 if (format != segment->format && start == 0) {
463 format = segment->format;
464 if (stop != 0)
465 stop = -1;
466 if (time != 0)
467 time = -1;
468 }
470 g_return_if_fail (segment->format == format);
472 if (update) {
473 if (G_LIKELY (segment->rate > 0.0)) {
474 /* an update to the current segment is done, elapsed time is
475 * difference between the old start and new start. */
476 if (start > segment->start)
477 duration = start - segment->start;
478 else
479 duration = 0;
480 } else {
481 /* for negative rates, the elapsed duration is the diff between the stop
482 * positions */
483 if (stop != -1 && stop < segment->stop)
484 duration = segment->stop - stop;
485 else
486 duration = 0;
487 }
488 /* update last_stop to be a valid value in the updated segment */
489 if (start > segment->last_stop)
490 last_stop = start;
491 else if (stop != -1 && stop < segment->last_stop)
492 last_stop = stop;
493 else
494 last_stop = segment->last_stop;
495 } else {
496 /* the new segment has to be aligned with the old segment.
497 * We first update the accumulated time of the previous
498 * segment. the accumulated time is used when syncing to the
499 * clock. */
500 if (segment->stop != -1) {
501 duration = segment->stop - segment->start;
502 } else if (segment->last_stop != -1) {
503 /* else use last seen timestamp as segment stop */
504 duration = segment->last_stop - segment->start;
505 } else {
506 /* else we don't know and throw a warning.. really, this should
507 * be fixed in the element. */
508 g_warning ("closing segment of unknown duration, assuming duration of 0");
509 duration = 0;
510 }
511 /* position the last_stop to the next expected position in the new segment,
512 * which is the start or the stop of the segment */
513 if (rate > 0.0)
514 last_stop = start;
515 else
516 last_stop = stop;
517 }
518 /* use previous rate to calculate duration */
519 if (G_LIKELY (segment->abs_rate != 1.0))
520 duration /= segment->abs_rate;
522 /* accumulate duration */
523 segment->accum += duration;
525 /* then update the current segment */
526 segment->rate = rate;
527 segment->abs_rate = ABS (rate);
528 segment->applied_rate = applied_rate;
529 segment->start = start;
530 segment->last_stop = last_stop;
531 segment->stop = stop;
532 segment->time = time;
533 }
535 /**
536 * gst_segment_to_stream_time:
537 * @segment: a #GstSegment structure.
538 * @format: the format of the segment.
539 * @position: the position in the segment
540 *
541 * Translate @position to stream time using the currently configured
542 * segment. The @position value must be between @segment start and
543 * stop value.
544 *
545 * This function is typically used by elements that need to operate on
546 * the stream time of the buffers it receives, such as effect plugins.
547 * In those use cases, @position is typically the buffer timestamp or
548 * clock time that one wants to convert to the stream time.
549 * The stream time is always between 0 and the total duration of the
550 * media stream.
551 *
552 * Returns: the position in stream_time or -1 when an invalid position
553 * was given.
554 */
555 gint64
556 gst_segment_to_stream_time (GstSegment * segment, GstFormat format,
557 gint64 position)
558 {
559 gint64 result, start, stop, time;
560 gdouble abs_applied_rate;
562 /* format does not matter for -1 */
563 if (G_UNLIKELY (position == -1))
564 return -1;
566 g_return_val_if_fail (segment != NULL, -1);
568 if (G_UNLIKELY (segment->format == GST_FORMAT_UNDEFINED))
569 segment->format = format;
571 /* if we have the position for the same format as the segment, we can compare
572 * the start and stop values, otherwise we assume 0 and -1 */
573 if (G_LIKELY (segment->format == format)) {
574 start = segment->start;
575 stop = segment->stop;
576 time = segment->time;
577 } else {
578 start = 0;
579 stop = -1;
580 time = 0;
581 }
583 /* outside of the segment boundary stop */
584 if (G_UNLIKELY (stop != -1 && position > stop))
585 return -1;
587 /* before the segment boundary */
588 if (G_UNLIKELY (position < start))
589 return -1;
591 /* time must be known */
592 if (G_UNLIKELY (time == -1))
593 return -1;
595 /* bring to uncorrected position in segment */
596 result = position - start;
598 abs_applied_rate = ABS (segment->applied_rate);
600 /* correct for applied rate if needed */
601 if (G_UNLIKELY (abs_applied_rate != 1.0))
602 result *= abs_applied_rate;
604 /* add or subtract from segment time based on applied rate */
605 if (G_LIKELY (segment->applied_rate > 0.0)) {
606 /* correct for segment time */
607 result += time;
608 } else {
609 /* correct for segment time, clamp at 0. Streams with a negative
610 * applied_rate have timestamps between start and stop, as usual, but have
611 * the time member starting high and going backwards. */
612 if (G_LIKELY (time > result))
613 result = time - result;
614 else
615 result = 0;
616 }
618 return result;
619 }
621 /**
622 * gst_segment_to_running_time:
623 * @segment: a #GstSegment structure.
624 * @format: the format of the segment.
625 * @position: the position in the segment
626 *
627 * Translate @position to the total running time using the currently configured
628 * and previously accumulated segments. Position is a value between @segment
629 * start and stop time.
630 *
631 * This function is typically used by elements that need to synchronize to the
632 * global clock in a pipeline. The runnning time is a constantly increasing value
633 * starting from 0. When gst_segment_init() is called, this value will reset to
634 * 0.
635 *
636 * This function returns -1 if the position is outside of @segment start and stop.
637 *
638 * Returns: the position as the total running time or -1 when an invalid position
639 * was given.
640 */
641 gint64
642 gst_segment_to_running_time (GstSegment * segment, GstFormat format,
643 gint64 position)
644 {
645 gint64 result;
646 gint64 start, stop, accum;
648 if (G_UNLIKELY (position == -1))
649 return -1;
651 g_return_val_if_fail (segment != NULL, -1);
653 if (G_UNLIKELY (segment->format == GST_FORMAT_UNDEFINED))
654 segment->format = format;
656 /* if we have the position for the same format as the segment, we can compare
657 * the start and stop values, otherwise we assume 0 and -1 */
658 if (G_LIKELY (segment->format == format)) {
659 start = segment->start;
660 stop = segment->stop;
661 accum = segment->accum;
662 } else {
663 start = 0;
664 stop = -1;
665 accum = 0;
666 }
668 /* before the segment boundary */
669 if (G_UNLIKELY (position < start))
670 return -1;
672 if (G_LIKELY (segment->rate > 0.0)) {
673 /* outside of the segment boundary stop */
674 if (G_UNLIKELY (stop != -1 && position > stop))
675 return -1;
677 /* bring to uncorrected position in segment */
678 result = position - start;
679 } else {
680 /* cannot continue if no stop position set or outside of
681 * the segment. */
682 if (G_UNLIKELY (stop == -1 || position > stop))
683 return -1;
685 /* bring to uncorrected position in segment */
686 result = stop - position;
687 }
689 /* scale based on the rate, avoid division by and conversion to
690 * float when not needed */
691 if (G_UNLIKELY (segment->abs_rate != 1.0))
692 result /= segment->abs_rate;
694 /* correct for accumulated segments */
695 result += accum;
697 return result;
698 }
700 /**
701 * gst_segment_clip:
702 * @segment: a #GstSegment structure.
703 * @format: the format of the segment.
704 * @start: the start position in the segment
705 * @stop: the stop position in the segment
706 * @clip_start: (out) (allow-none): the clipped start position in the segment
707 * @clip_stop: (out) (allow-none): the clipped stop position in the segment
708 *
709 * Clip the given @start and @stop values to the segment boundaries given
710 * in @segment. @start and @stop are compared and clipped to @segment
711 * start and stop values.
712 *
713 * If the function returns FALSE, @start and @stop are known to fall
714 * outside of @segment and @clip_start and @clip_stop are not updated.
715 *
716 * When the function returns TRUE, @clip_start and @clip_stop will be
717 * updated. If @clip_start or @clip_stop are different from @start or @stop
718 * respectively, the region fell partially in the segment.
719 *
720 * Note that when @stop is -1, @clip_stop will be set to the end of the
721 * segment. Depending on the use case, this may or may not be what you want.
722 *
723 * Returns: TRUE if the given @start and @stop times fall partially or
724 * completely in @segment, FALSE if the values are completely outside
725 * of the segment.
726 */
727 gboolean
728 gst_segment_clip (GstSegment * segment, GstFormat format, gint64 start,
729 gint64 stop, gint64 * clip_start, gint64 * clip_stop)
730 {
731 g_return_val_if_fail (segment != NULL, FALSE);
733 if (G_UNLIKELY (segment->format == GST_FORMAT_UNDEFINED))
734 segment->format = format;
735 else
736 g_return_val_if_fail (segment->format == format, FALSE);
738 /* if we have a stop position and a valid start and start is bigger,
739 * we're outside of the segment */
740 if (G_UNLIKELY (segment->stop != -1 && start != -1 && start >= segment->stop))
741 return FALSE;
743 /* if a stop position is given and is before the segment start,
744 * we're outside of the segment. Special case is were start
745 * and stop are equal to the segment start. In that case we
746 * are inside the segment. */
747 if (G_UNLIKELY (stop != -1 && (stop < segment->start || (start != stop
748 && stop == segment->start))))
749 return FALSE;
751 if (clip_start) {
752 if (start == -1)
753 *clip_start = -1;
754 else
755 *clip_start = MAX (start, segment->start);
756 }
758 if (clip_stop) {
759 if (stop == -1)
760 *clip_stop = segment->stop;
761 else if (segment->stop == -1)
762 *clip_stop = MAX (-1, stop);
763 else
764 *clip_stop = MIN (stop, segment->stop);
766 if (segment->duration != -1)
767 *clip_stop = MIN (*clip_stop, segment->duration);
768 }
770 return TRUE;
771 }
773 /**
774 * gst_segment_to_position:
775 * @segment: a #GstSegment structure.
776 * @format: the format of the segment.
777 * @running_time: the running_time in the segment
778 *
779 * Convert @running_time into a position in the segment so that
780 * gst_segment_to_running_time() with that position returns @running_time.
781 *
782 * Returns: the position in the segment for @running_time. This function returns
783 * -1 when @running_time is -1 or when it is not inside @segment.
784 *
785 * Since: 0.10.24
786 */
787 gint64
788 gst_segment_to_position (GstSegment * segment, GstFormat format,
789 gint64 running_time)
790 {
791 gint64 result;
792 gint64 start, stop, accum;
794 g_return_val_if_fail (segment != NULL, -1);
796 if (G_UNLIKELY (running_time == -1))
797 return -1;
799 if (G_UNLIKELY (segment->format == GST_FORMAT_UNDEFINED))
800 segment->format = format;
802 /* if we have the position for the same format as the segment, we can compare
803 * the start and stop values, otherwise we assume 0 and -1 */
804 if (G_LIKELY (segment->format == format)) {
805 start = segment->start;
806 stop = segment->stop;
807 accum = segment->accum;
808 } else {
809 start = 0;
810 stop = -1;
811 accum = 0;
812 }
814 /* this running_time was for a previous segment */
815 if (running_time < accum)
816 return -1;
818 /* start by subtracting the accumulated time */
819 result = running_time - accum;
821 /* move into the segment at the right rate */
822 if (G_UNLIKELY (segment->abs_rate != 1.0))
823 result = ceil (result * segment->abs_rate);
825 if (G_LIKELY (segment->rate > 0.0)) {
826 /* bring to corrected position in segment */
827 result += start;
829 /* outside of the segment boundary stop */
830 if (G_UNLIKELY (stop != -1 && result > stop))
831 return -1;
832 } else {
833 /* cannot continue if no stop position set or outside of
834 * the segment. */
835 if (G_UNLIKELY (stop == -1 || result + start > stop))
836 return -1;
838 /* bring to corrected position in segment */
839 result = stop - result;
840 }
841 return result;
842 }
845 /**
846 * gst_segment_set_running_time:
847 * @segment: a #GstSegment structure.
848 * @format: the format of the segment.
849 * @running_time: the running_time in the segment
850 *
851 * Adjust the start/stop and accum values of @segment such that the next valid
852 * buffer will be one with @running_time.
853 *
854 * Returns: %TRUE if the segment could be updated successfully. If %FALSE is
855 * returned, @running_time is -1 or not in @segment.
856 *
857 * Since: 0.10.24
858 */
859 gboolean
860 gst_segment_set_running_time (GstSegment * segment, GstFormat format,
861 gint64 running_time)
862 {
863 gint64 position;
864 gint64 start, stop, last_stop;
866 /* start by bringing the running_time into the segment position */
867 position = gst_segment_to_position (segment, format, running_time);
869 /* we must have a valid position now */
870 if (G_UNLIKELY (position == -1))
871 return FALSE;
873 start = segment->start;
874 stop = segment->stop;
875 last_stop = segment->last_stop;
877 if (G_LIKELY (segment->rate > 0.0)) {
878 /* update the start/last_stop and time values */
879 start = position;
880 if (last_stop < start)
881 last_stop = start;
882 } else {
883 /* reverse, update stop */
884 stop = position;
885 /* if we were past the position, go back */
886 if (last_stop > stop)
887 last_stop = stop;
888 }
889 /* and accumulated time is exactly the running time */
890 segment->time = gst_segment_to_stream_time (segment, format, start);
891 segment->start = start;
892 segment->stop = stop;
893 segment->last_stop = last_stop;
894 segment->accum = running_time;
896 return TRUE;
897 }