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DEFINITIONS
This source file includes following definitions.
- gst_segment_copy
- gst_segment_get_type
- gst_segment_new
- gst_segment_free
- gst_segment_init
- gst_segment_set_duration
- gst_segment_set_last_stop
- gst_segment_set_seek
- gst_segment_set_newsegment
- gst_segment_set_newsegment_full
- gst_segment_to_stream_time
- gst_segment_to_running_time
- gst_segment_clip
- gst_segment_to_position
- gst_segment_set_running_time
/* GStreamer
* Copyright (C) 2005 Wim Taymans <wim@fluendo.com>
*
* gstsegment.c: GstSegment subsystem
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include "gst_private.h"
#include <math.h>
#include "gstutils.h"
#include "gstsegment.h"
/**
* SECTION:gstsegment
* @short_description: Structure describing the configured region of interest
* in a media file.
* @see_also: #GstEvent
*
* This helper structure holds the relevant values for tracking the region of
* interest in a media file, called a segment.
*
* The structure can be used for two purposes:
* <itemizedlist>
* <listitem><para>performing seeks (handling seek events)</para></listitem>
* <listitem><para>tracking playback regions (handling newsegment events)</para></listitem>
* </itemizedlist>
*
* The segment is usually configured by the application with a seek event which
* is propagated upstream and eventually handled by an element that performs the seek.
*
* The configured segment is then propagated back downstream with a newsegment event.
* This information is then used to clip media to the segment boundaries.
*
* A segment structure is initialized with gst_segment_init(), which takes a #GstFormat
* that will be used as the format of the segment values. The segment will be configured
* with a start value of 0 and a stop/duration of -1, which is undefined. The default
* rate and applied_rate is 1.0.
*
* If the segment is used for managing seeks, the segment duration should be set with
* gst_segment_set_duration(). The public duration field contains the duration of the
* segment. When using the segment for seeking, the start and time members should
* normally be left to their default 0 value. The stop position is left to -1 unless
* explicitly configured to a different value after a seek event.
*
* The current position in the segment should be set with the gst_segment_set_last_stop().
* The public last_stop field contains the last set stop position in the segment.
*
* For elements that perform seeks, the current segment should be updated with the
* gst_segment_set_seek() and the values from the seek event. This method will update
* all the segment fields. The last_stop field will contain the new playback position.
* If the cur_type was different from GST_SEEK_TYPE_NONE, playback continues from
* the last_stop position, possibly with updated flags or rate.
*
* For elements that want to use #GstSegment to track the playback region, use
* gst_segment_set_newsegment() to update the segment fields with the information from
* the newsegment event. The gst_segment_clip() method can be used to check and clip
* the media data to the segment boundaries.
*
* For elements that want to synchronize to the pipeline clock, gst_segment_to_running_time()
* can be used to convert a timestamp to a value that can be used to synchronize
* to the clock. This function takes into account all accumulated segments as well as
* any rate or applied_rate conversions.
*
* For elements that need to perform operations on media data in stream_time,
* gst_segment_to_stream_time() can be used to convert a timestamp and the segment
* info to stream time (which is always between 0 and the duration of the stream).
*
* Last reviewed on 2007-05-17 (0.10.13)
*/
/**
* gst_segment_copy:
* @segment: a #GstSegment
*
* Create a copy of given @segment.
*
* Returns: a new #GstSegment, free with gst_segment_free().
*
* Since: 0.10.20
*/
GstSegment *
gst_segment_copy (GstSegment * segment)
{
GstSegment *result = NULL;
if (segment) {
result = (GstSegment *) g_slice_copy (sizeof (GstSegment), segment);
}
return result;
}
GType
gst_segment_get_type (void)
{
static GType gst_segment_type = 0;
if (G_UNLIKELY (gst_segment_type == 0)) {
gst_segment_type = g_boxed_type_register_static ("GstSegment",
(GBoxedCopyFunc) gst_segment_copy, (GBoxedFreeFunc) gst_segment_free);
}
return gst_segment_type;
}
/**
* gst_segment_new:
*
* Allocate a new #GstSegment structure and initialize it using
* gst_segment_init().
*
* Returns: a new #GstSegment, free with gst_segment_free().
*/
GstSegment *
gst_segment_new (void)
{
GstSegment *result;
result = g_slice_new0 (GstSegment);
gst_segment_init (result, GST_FORMAT_UNDEFINED);
return result;
}
/**
* gst_segment_free:
* @segment: a #GstSegment
*
* Free the allocated segment @segment.
*/
void
gst_segment_free (GstSegment * segment)
{
g_slice_free (GstSegment, segment);
}
/**
* gst_segment_init:
* @segment: a #GstSegment structure.
* @format: the format of the segment.
*
* The start/last_stop positions are set to 0 and the stop/duration
* fields are set to -1 (unknown). The default rate of 1.0 and no
* flags are set.
*
* Initialize @segment to its default values.
*/
void
gst_segment_init (GstSegment * segment, GstFormat format)
{
g_return_if_fail (segment != NULL);
segment->rate = 1.0;
segment->abs_rate = 1.0;
segment->applied_rate = 1.0;
segment->format = format;
segment->flags = 0;
segment->start = 0;
segment->stop = -1;
segment->time = 0;
segment->accum = 0;
segment->last_stop = 0;
segment->duration = -1;
}
/**
* gst_segment_set_duration:
* @segment: a #GstSegment structure.
* @format: the format of the segment.
* @duration: the duration of the segment info or -1 if unknown.
*
* Set the duration of the segment to @duration. This function is mainly
* used by elements that perform seeking and know the total duration of the
* segment.
*
* This field should be set to allow seeking requests relative to the
* duration.
*/
void
gst_segment_set_duration (GstSegment * segment, GstFormat format,
gint64 duration)
{
g_return_if_fail (segment != NULL);
if (G_UNLIKELY (segment->format == GST_FORMAT_UNDEFINED))
segment->format = format;
else
g_return_if_fail (segment->format == format);
segment->duration = duration;
}
/**
* gst_segment_set_last_stop:
* @segment: a #GstSegment structure.
* @format: the format of the segment.
* @position: the position
*
* Set the last observed stop position in the segment to @position.
*
* This field should be set to allow seeking requests relative to the
* current playing position.
*/
void
gst_segment_set_last_stop (GstSegment * segment, GstFormat format,
gint64 position)
{
g_return_if_fail (segment != NULL);
if (G_UNLIKELY (segment->format == GST_FORMAT_UNDEFINED))
segment->format = format;
else
g_return_if_fail (segment->format == format);
segment->last_stop = MAX (segment->start, position);
}
/**
* gst_segment_set_seek:
* @segment: a #GstSegment structure.
* @rate: the rate of the segment.
* @format: the format of the segment.
* @flags: the seek flags for the segment
* @start_type: the seek method
* @start: the seek start value
* @stop_type: the seek method
* @stop: the seek stop value
* @update: boolean holding whether last_stop was updated.
*
* Update the segment structure with the field values of a seek event (see
* gst_event_new_seek()).
*
* After calling this method, the segment field last_stop and time will
* contain the requested new position in the segment. The new requested
* position in the segment depends on @rate and @start_type and @stop_type.
*
* For positive @rate, the new position in the segment is the new @segment
* start field when it was updated with a @start_type different from
* #GST_SEEK_TYPE_NONE. If no update was performed on @segment start position
* (#GST_SEEK_TYPE_NONE), @start is ignored and @segment last_stop is
* unmodified.
*
* For negative @rate, the new position in the segment is the new @segment
* stop field when it was updated with a @stop_type different from
* #GST_SEEK_TYPE_NONE. If no stop was previously configured in the segment, the
* duration of the segment will be used to update the stop position.
* If no update was performed on @segment stop position (#GST_SEEK_TYPE_NONE),
* @stop is ignored and @segment last_stop is unmodified.
*
* The applied rate of the segment will be set to 1.0 by default.
* If the caller can apply a rate change, it should update @segment
* rate and applied_rate after calling this function.
*
* @update will be set to TRUE if a seek should be performed to the segment
* last_stop field. This field can be FALSE if, for example, only the @rate
* has been changed but not the playback position.
*/
void
gst_segment_set_seek (GstSegment * segment, gdouble rate,
GstFormat format, GstSeekFlags flags,
GstSeekType start_type, gint64 start,
GstSeekType stop_type, gint64 stop, gboolean * update)
{
gboolean update_stop, update_start;
gint64 last_stop;
g_return_if_fail (rate != 0.0);
g_return_if_fail (segment != NULL);
if (G_UNLIKELY (segment->format == GST_FORMAT_UNDEFINED))
segment->format = format;
update_start = update_stop = TRUE;
/* segment->start is never invalid */
switch (start_type) {
case GST_SEEK_TYPE_NONE:
/* no update to segment, take previous start */
start = segment->start;
update_start = FALSE;
break;
case GST_SEEK_TYPE_SET:
/* start holds desired position, map -1 to the start */
if (start == -1)
start = 0;
/* start must be 0 or the formats must match */
g_return_if_fail (start == 0 || segment->format == format);
break;
case GST_SEEK_TYPE_CUR:
g_return_if_fail (start == 0 || segment->format == format);
/* add start to currently configured segment */
start = segment->start + start;
break;
case GST_SEEK_TYPE_END:
if (segment->duration != -1) {
g_return_if_fail (start == 0 || segment->format == format);
/* add start to total length */
start = segment->duration + start;
} else {
/* no update if duration unknown */
start = segment->start;
update_start = FALSE;
}
break;
}
/* bring in sane range */
if (segment->duration != -1)
start = CLAMP (start, 0, segment->duration);
else
start = MAX (start, 0);
/* stop can be -1 if we have not configured a stop. */
switch (stop_type) {
case GST_SEEK_TYPE_NONE:
stop = segment->stop;
update_stop = FALSE;
break;
case GST_SEEK_TYPE_SET:
/* stop holds required value, if it's not -1, it must be of the same
* format as the segment. */
g_return_if_fail (stop == -1 || segment->format == format);
break;
case GST_SEEK_TYPE_CUR:
if (segment->stop != -1) {
/* only add compatible formats or 0 */
g_return_if_fail (stop == 0 || segment->format == format);
stop = segment->stop + stop;
} else
stop = -1;
break;
case GST_SEEK_TYPE_END:
if (segment->duration != -1) {
/* only add compatible formats or 0 */
g_return_if_fail (stop == 0 || segment->format == format);
stop = segment->duration + stop;
} else {
stop = segment->stop;
update_stop = FALSE;
}
break;
}
/* if we have a valid stop time, make sure it is clipped */
if (stop != -1) {
if (segment->duration != -1)
stop = CLAMP (stop, 0, segment->duration);
else
stop = MAX (stop, 0);
}
/* we can't have stop before start */
if (stop != -1)
g_return_if_fail (start <= stop);
segment->rate = rate;
segment->abs_rate = ABS (rate);
segment->applied_rate = 1.0;
segment->flags = flags;
segment->start = start;
segment->stop = stop;
segment->time = start;
last_stop = segment->last_stop;
if (update_start && rate > 0.0) {
last_stop = start;
}
if (update_stop && rate < 0.0) {
if (stop != -1)
last_stop = stop;
else {
if (segment->duration != -1)
last_stop = segment->duration;
else
last_stop = 0;
}
}
/* set update arg to reflect update of last_stop */
if (update)
*update = last_stop != segment->last_stop;
/* update new position */
segment->last_stop = last_stop;
}
/**
* gst_segment_set_newsegment:
* @segment: a #GstSegment structure.
* @update: flag indicating a new segment is started or updated
* @rate: the rate of the segment.
* @format: the format of the segment.
* @start: the new start value
* @stop: the new stop value
* @time: the new stream time
*
* Update the segment structure with the field values of a new segment event and
* with a default applied_rate of 1.0.
*
* Since: 0.10.6
*/
void
gst_segment_set_newsegment (GstSegment * segment, gboolean update, gdouble rate,
GstFormat format, gint64 start, gint64 stop, gint64 time)
{
gst_segment_set_newsegment_full (segment, update, rate, 1.0, format, start,
stop, time);
}
/**
* gst_segment_set_newsegment_full:
* @segment: a #GstSegment structure.
* @update: flag indicating a new segment is started or updated
* @rate: the rate of the segment.
* @applied_rate: the applied rate of the segment.
* @format: the format of the segment.
* @start: the new start value
* @stop: the new stop value
* @time: the new stream time
*
* Update the segment structure with the field values of a new segment event.
*/
void
gst_segment_set_newsegment_full (GstSegment * segment, gboolean update,
gdouble rate, gdouble applied_rate, GstFormat format, gint64 start,
gint64 stop, gint64 time)
{
gint64 duration, last_stop;
g_return_if_fail (rate != 0.0);
g_return_if_fail (applied_rate != 0.0);
g_return_if_fail (segment != NULL);
GST_DEBUG ("configuring segment update %d, rate %lf, format %s, "
"start %" G_GINT64_FORMAT ", stop %" G_GINT64_FORMAT ", position %"
G_GINT64_FORMAT, update, rate, gst_format_get_name (format), start,
stop, time);
GST_DEBUG ("old segment was: %" GST_SEGMENT_FORMAT, segment);
if (G_UNLIKELY (segment->format == GST_FORMAT_UNDEFINED))
segment->format = format;
/* any other format with 0 also gives time 0, the other values are
* invalid in the format though. */
if (format != segment->format && start == 0) {
format = segment->format;
if (stop != 0)
stop = -1;
if (time != 0)
time = -1;
}
g_return_if_fail (segment->format == format);
if (update) {
if (G_LIKELY (segment->rate > 0.0)) {
/* an update to the current segment is done, elapsed time is
* difference between the old start and new start. */
if (start > segment->start)
duration = start - segment->start;
else
duration = 0;
} else {
/* for negative rates, the elapsed duration is the diff between the stop
* positions */
if (stop != -1 && stop < segment->stop)
duration = segment->stop - stop;
else
duration = 0;
}
/* update last_stop to be a valid value in the updated segment */
if (start > segment->last_stop)
last_stop = start;
else if (stop != -1 && stop < segment->last_stop)
last_stop = stop;
else
last_stop = segment->last_stop;
} else {
/* the new segment has to be aligned with the old segment.
* We first update the accumulated time of the previous
* segment. the accumulated time is used when syncing to the
* clock. */
if (segment->stop != -1) {
duration = segment->stop - segment->start;
} else if (segment->last_stop != -1) {
/* else use last seen timestamp as segment stop */
duration = segment->last_stop - segment->start;
} else {
/* else we don't know and throw a warning.. really, this should
* be fixed in the element. */
g_warning ("closing segment of unknown duration, assuming duration of 0");
duration = 0;
}
/* position the last_stop to the next expected position in the new segment,
* which is the start or the stop of the segment */
if (rate > 0.0)
last_stop = start;
else
last_stop = stop;
}
/* use previous rate to calculate duration */
if (G_LIKELY (segment->abs_rate != 1.0))
duration /= segment->abs_rate;
/* accumulate duration */
segment->accum += duration;
/* then update the current segment */
segment->rate = rate;
segment->abs_rate = ABS (rate);
segment->applied_rate = applied_rate;
segment->start = start;
segment->last_stop = last_stop;
segment->stop = stop;
segment->time = time;
}
/**
* gst_segment_to_stream_time:
* @segment: a #GstSegment structure.
* @format: the format of the segment.
* @position: the position in the segment
*
* Translate @position to stream time using the currently configured
* segment. The @position value must be between @segment start and
* stop value.
*
* This function is typically used by elements that need to operate on
* the stream time of the buffers it receives, such as effect plugins.
* In those use cases, @position is typically the buffer timestamp or
* clock time that one wants to convert to the stream time.
* The stream time is always between 0 and the total duration of the
* media stream.
*
* Returns: the position in stream_time or -1 when an invalid position
* was given.
*/
gint64
gst_segment_to_stream_time (GstSegment * segment, GstFormat format,
gint64 position)
{
gint64 result, start, stop, time;
gdouble abs_applied_rate;
g_return_val_if_fail (segment != NULL, -1);
/* format does not matter for -1 */
if (G_UNLIKELY (position == -1))
return -1;
if (G_UNLIKELY (segment->format == GST_FORMAT_UNDEFINED))
segment->format = format;
/* if we have the position for the same format as the segment, we can compare
* the start and stop values, otherwise we assume 0 and -1 */
if (G_LIKELY (segment->format == format)) {
start = segment->start;
stop = segment->stop;
time = segment->time;
} else {
start = 0;
stop = -1;
time = 0;
}
/* outside of the segment boundary stop */
if (G_UNLIKELY (stop != -1 && position > stop))
return -1;
/* before the segment boundary */
if (G_UNLIKELY (position < start))
return -1;
/* time must be known */
if (G_UNLIKELY (time == -1))
return -1;
/* bring to uncorrected position in segment */
result = position - start;
abs_applied_rate = ABS (segment->applied_rate);
/* correct for applied rate if needed */
if (G_UNLIKELY (abs_applied_rate != 1.0))
result *= abs_applied_rate;
/* add or subtract from segment time based on applied rate */
if (G_LIKELY (segment->applied_rate > 0.0)) {
/* correct for segment time */
result += time;
} else {
/* correct for segment time, clamp at 0. Streams with a negative
* applied_rate have timestamps between start and stop, as usual, but have
* the time member starting high and going backwards. */
if (G_LIKELY (time > result))
result = time - result;
else
result = 0;
}
return result;
}
/**
* gst_segment_to_running_time:
* @segment: a #GstSegment structure.
* @format: the format of the segment.
* @position: the position in the segment
*
* Translate @position to the total running time using the currently configured
* and previously accumulated segments. Position is a value between @segment
* start and stop time.
*
* This function is typically used by elements that need to synchronize to the
* global clock in a pipeline. The runnning time is a constantly increasing value
* starting from 0. When gst_segment_init() is called, this value will reset to
* 0.
*
* This function returns -1 if the position is outside of @segment start and stop.
*
* Returns: the position as the total running time or -1 when an invalid position
* was given.
*/
gint64
gst_segment_to_running_time (GstSegment * segment, GstFormat format,
gint64 position)
{
gint64 result;
gint64 start, stop, accum;
g_return_val_if_fail (segment != NULL, -1);
if (G_UNLIKELY (position == -1))
return -1;
if (G_UNLIKELY (segment->format == GST_FORMAT_UNDEFINED))
segment->format = format;
/* if we have the position for the same format as the segment, we can compare
* the start and stop values, otherwise we assume 0 and -1 */
if (G_LIKELY (segment->format == format)) {
start = segment->start;
stop = segment->stop;
accum = segment->accum;
} else {
start = 0;
stop = -1;
accum = 0;
}
/* before the segment boundary */
if (G_UNLIKELY (position < start))
return -1;
if (G_LIKELY (segment->rate > 0.0)) {
/* outside of the segment boundary stop */
if (G_UNLIKELY (stop != -1 && position > stop))
return -1;
/* bring to uncorrected position in segment */
result = position - start;
} else {
/* cannot continue if no stop position set or outside of
* the segment. */
if (G_UNLIKELY (stop == -1 || position > stop))
return -1;
/* bring to uncorrected position in segment */
result = stop - position;
}
/* scale based on the rate, avoid division by and conversion to
* float when not needed */
if (G_UNLIKELY (segment->abs_rate != 1.0))
result /= segment->abs_rate;
/* correct for accumulated segments */
result += accum;
return result;
}
/**
* gst_segment_clip:
* @segment: a #GstSegment structure.
* @format: the format of the segment.
* @start: the start position in the segment
* @stop: the stop position in the segment
* @clip_start: the clipped start position in the segment
* @clip_stop: the clipped stop position in the segment
*
* Clip the given @start and @stop values to the segment boundaries given
* in @segment. @start and @stop are compared and clipped to @segment
* start and stop values.
*
* If the function returns FALSE, @start and @stop are known to fall
* outside of @segment and @clip_start and @clip_stop are not updated.
*
* When the function returns TRUE, @clip_start and @clip_stop will be
* updated. If @clip_start or @clip_stop are different from @start or @stop
* respectively, the region fell partially in the segment.
*
* Note that when @stop is -1, @clip_stop will be set to the end of the
* segment. Depending on the use case, this may or may not be what you want.
*
* Returns: TRUE if the given @start and @stop times fall partially or
* completely in @segment, FALSE if the values are completely outside
* of the segment.
*/
gboolean
gst_segment_clip (GstSegment * segment, GstFormat format, gint64 start,
gint64 stop, gint64 * clip_start, gint64 * clip_stop)
{
g_return_val_if_fail (segment != NULL, FALSE);
if (G_UNLIKELY (segment->format == GST_FORMAT_UNDEFINED))
segment->format = format;
else
g_return_val_if_fail (segment->format == format, FALSE);
/* if we have a stop position and a valid start and start is bigger,
* we're outside of the segment */
if (G_UNLIKELY (segment->stop != -1 && start != -1 && start >= segment->stop))
return FALSE;
/* if a stop position is given and is before the segment start,
* we're outside of the segment. Special case is were start
* and stop are equal to the segment start. In that case we
* are inside the segment. */
if (G_UNLIKELY (stop != -1 && (stop < segment->start || (start != stop
&& stop == segment->start))))
return FALSE;
if (clip_start) {
if (start == -1)
*clip_start = -1;
else
*clip_start = MAX (start, segment->start);
}
if (clip_stop) {
if (stop == -1)
*clip_stop = segment->stop;
else if (segment->stop == -1)
*clip_stop = MAX (-1, stop);
else
*clip_stop = MIN (stop, segment->stop);
if (segment->duration != -1)
*clip_stop = MIN (*clip_stop, segment->duration);
}
return TRUE;
}
/**
* gst_segment_to_position:
* @segment: a #GstSegment structure.
* @format: the format of the segment.
* @running_time: the running_time in the segment
*
* Convert @running_time into a position in the segment so that
* gst_segment_to_running_time() with that position returns @running_time.
*
* Returns: the position in the segment for @running_time. This function returns
* -1 when @running_time is -1 or when it is not inside @segment.
*
* Since: 0.10.24
*/
gint64
gst_segment_to_position (GstSegment * segment, GstFormat format,
gint64 running_time)
{
gint64 result;
gint64 start, stop, accum;
g_return_val_if_fail (segment != NULL, -1);
if (G_UNLIKELY (running_time == -1))
return -1;
if (G_UNLIKELY (segment->format == GST_FORMAT_UNDEFINED))
segment->format = format;
/* if we have the position for the same format as the segment, we can compare
* the start and stop values, otherwise we assume 0 and -1 */
if (G_LIKELY (segment->format == format)) {
start = segment->start;
stop = segment->stop;
accum = segment->accum;
} else {
start = 0;
stop = -1;
accum = 0;
}
/* this running_time was for a previous segment */
if (running_time < accum)
return -1;
/* start by subtracting the accumulated time */
result = running_time - accum;
/* move into the segment at the right rate */
if (G_UNLIKELY (segment->abs_rate != 1.0))
result = ceil (result * segment->abs_rate);
if (G_LIKELY (segment->rate > 0.0)) {
/* bring to corrected position in segment */
result += start;
/* outside of the segment boundary stop */
if (G_UNLIKELY (stop != -1 && result > stop))
return -1;
} else {
/* cannot continue if no stop position set or outside of
* the segment. */
if (G_UNLIKELY (stop == -1 || result + start > stop))
return -1;
/* bring to corrected position in segment */
result = stop - result;
}
return result;
}
/**
* gst_segment_set_running_time:
* @segment: a #GstSegment structure.
* @format: the format of the segment.
* @running_time: the running_time in the segment
*
* Adjust the start/stop and accum values of @segment such that the next valid
* buffer will be one with @running_time.
*
* Returns: %TRUE if the segment could be updated successfully. If %FALSE is
* returned, @running_time is -1 or not in @segment.
*
* Since: 0.10.24
*/
gboolean
gst_segment_set_running_time (GstSegment * segment, GstFormat format,
gint64 running_time)
{
gint64 position;
gint64 start, stop, last_stop;
/* start by bringing the running_time into the segment position */
position = gst_segment_to_position (segment, format, running_time);
/* we must have a valid position now */
if (G_UNLIKELY (position == -1))
return FALSE;
start = segment->start;
stop = segment->stop;
last_stop = segment->last_stop;
if (G_LIKELY (segment->rate > 0.0)) {
/* update the start/last_stop and time values */
start = position;
if (last_stop < start)
last_stop = start;
} else {
/* reverse, update stop */
stop = position;
/* if we were past the position, go back */
if (last_stop > stop)
last_stop = stop;
}
/* and accumulated time is exactly the running time */
segment->time = gst_segment_to_stream_time (segment, format, start);
segment->start = start;
segment->stop = stop;
segment->last_stop = last_stop;
segment->accum = running_time;
return TRUE;
}