gstreamer/gst/gstsegment.c

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/* 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 "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 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.
*
* 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_pos field will contain the new playback position.
* If the cur_type was different from GST_SEEK_TYPE_NONE, playback continues from
* the last_pos position, possibly with updated flags or rate.
*
* For elements that want to us #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.
*
* 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 2005-12-12 (0.10.0)
*/
static GstSegment *
gst_segment_copy (GstSegment * segment)
{
GstSegment *result = NULL;
if (segment) {
result = gst_segment_new ();
memcpy (result, segment, sizeof (GstSegment));
}
return NULL;
}
GType
gst_segment_get_type (void)
{
static GType gst_segment_type = 0;
if (!gst_segment_type) {
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_new0 (GstSegment, 1);
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_free (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->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.
*
* 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 request relative to the
* duration.
*/
void
gst_segment_set_duration (GstSegment * segment, GstFormat format,
gint64 duration)
{
g_return_if_fail (segment != NULL);
if (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.
*/
void
gst_segment_set_last_stop (GstSegment * segment, GstFormat format,
gint64 position)
{
g_return_if_fail (segment != NULL);
if (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
* @cur_type: the seek method
* @cur: the seek start value
* @stop_type: the seek method
* @stop: the seek stop value
* @update: boolean holding whether an update the current segment is
* needed.
*
* Update the segment structure with the field values of a seek event.
*
* After calling this method, the segment field last_stop will contain
* the requested new position in the segment. If the cur_type is different
* from GST_SEEK_TYPE_NONE, the current position is not updated and
* streaming should continue from the last position, possibly with
* updated rate, flags or stop position.
*/
void
gst_segment_set_seek (GstSegment * segment, gdouble rate,
GstFormat format, GstSeekFlags flags,
GstSeekType cur_type, gint64 cur,
GstSeekType stop_type, gint64 stop, gboolean * update)
{
gboolean update_stop, update_start;
g_return_if_fail (rate != 0.0);
g_return_if_fail (segment != NULL);
if (segment->format == GST_FORMAT_UNDEFINED)
segment->format = format;
else
g_return_if_fail (segment->format == format);
update_stop = update_start = TRUE;
/* start is never invalid */
switch (cur_type) {
case GST_SEEK_TYPE_NONE:
/* no update to segment */
cur = segment->start;
update_start = FALSE;
break;
case GST_SEEK_TYPE_SET:
/* cur holds desired position */
break;
case GST_SEEK_TYPE_CUR:
/* add cur to currently configure segment */
cur = segment->start + cur;
break;
case GST_SEEK_TYPE_END:
if (segment->duration != -1) {
/* add cur to total length */
cur = segment->duration + cur;
} else {
/* no update if duration unknown */
cur = segment->start;
update_start = FALSE;
}
break;
}
/* bring in sane range */
if (segment->duration != -1)
cur = CLAMP (cur, 0, segment->duration);
else
cur = MAX (cur, 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 folds required value */
break;
case GST_SEEK_TYPE_CUR:
if (segment->stop != -1)
stop = segment->stop + stop;
else
stop = -1;
break;
case GST_SEEK_TYPE_END:
if (segment->duration != -1)
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 (cur <= stop);
segment->rate = rate;
segment->abs_rate = ABS (rate);
segment->flags = flags;
segment->start = cur;
if (update_start) {
segment->last_stop = cur;
}
segment->time = segment->last_stop;
segment->stop = stop;
if (update)
*update = update_start || update_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.
*/
void
gst_segment_set_newsegment (GstSegment * segment, gboolean update, gdouble rate,
GstFormat format, gint64 start, gint64 stop, gint64 time)
{
gint64 duration;
g_return_if_fail (rate != 0.0);
g_return_if_fail (segment != NULL);
if (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) {
/* an update to the current segment is done, elapsed time is
* difference between the old start and new start. */
duration = start - segment->start;
} 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 (GST_CLOCK_TIME_IS_VALID (segment->stop)) {
duration = segment->stop - segment->start;
} else if (GST_CLOCK_TIME_IS_VALID (segment->last_stop)) {
/* else use last seen timestamp as segment stop */
duration = segment->last_stop - segment->start;
} else {
/* else we don't know */
duration = 0;
}
}
/* use previous rate to calculate duration */
segment->accum += gst_gdouble_to_guint64 (
(gst_guint64_to_gdouble (duration) / segment->abs_rate));
/* then update the current segment */
segment->rate = rate;
segment->abs_rate = ABS (rate);
segment->start = start;
segment->last_stop = start;
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.
*
* This function is typically used by elements that need to operate on
* the stream time of the buffers it receives, such as effect plugins.
*
* Returns: the position in stream_time.
*/
gint64
gst_segment_to_stream_time (GstSegment * segment, GstFormat format,
gint64 position)
{
gint64 result, time;
g_return_val_if_fail (segment != NULL, FALSE);
if (segment->format == GST_FORMAT_UNDEFINED)
segment->format = format;
else
g_return_val_if_fail (segment->format == format, FALSE);
if ((time = segment->time) == -1)
time = 0;
if (position != -1 && position >= segment->start)
result = ((position - segment->start) / segment->abs_rate) + time;
else
result = -1;
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
* segment.
*
* This function is typically used by elements that need to synchronize to the
* global clock in a pipeline.
*
* Returns: the position as the total running time.
*/
gint64
gst_segment_to_running_time (GstSegment * segment, GstFormat format,
gint64 position)
{
gint64 result;
g_return_val_if_fail (segment != NULL, -1);
if (segment->format == GST_FORMAT_UNDEFINED)
segment->format = format;
else if (segment->accum)
g_return_val_if_fail (segment->format == format, -1);
if (position != -1 && position >= segment->start)
result = ((position - segment->start) / segment->abs_rate) + segment->accum;
else
result = -1;
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.
*
* Returns: TRUE if the given @start and @stop times fall partially 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 (segment->format == GST_FORMAT_UNDEFINED)
segment->format = format;
else
g_return_val_if_fail (segment->format == format, FALSE);
/* we need a valid start position */
if (start == -1)
return FALSE;
/* if we have a stop position and start is bigger, we're
* outside of the segment */
if (segment->stop != -1 && start >= segment->stop)
return FALSE;
/* if a stop position is given and is before the segment start,
* we're outside of the segment */
if (stop != -1 && stop <= segment->start)
return FALSE;
if (clip_start)
*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;
}