--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gstreamer_core/gst/gstsegment.c	Thu Dec 17 08:53:32 2009 +0200
@@ -0,0 +1,784 @@
+/* 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 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)
+ */
+
+static GstSegment *
+gst_segment_copy (GstSegment * segment)
+{
+  GstSegment *result = NULL;
+
+  if (segment) {
+    result = gst_segment_new ();
+    memcpy (result, segment, sizeof (GstSegment));
+  }
+  return result;
+}
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+
+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().
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+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.
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+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.
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+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.
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+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.
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+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.
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+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
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+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.
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+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;
+
+  g_return_if_fail (rate != 0.0);
+  g_return_if_fail (applied_rate != 0.0);
+  g_return_if_fail (segment != NULL);
+
+  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 (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;
+    }
+  } 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;
+    }
+  }
+  /* use previous rate to calculate duration */
+  if (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 = 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. 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.
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+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 (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 (abs_applied_rate != 1.0)
+    result *= abs_applied_rate;
+
+  /* add or subtract from segment time based on applied rate */
+  if (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 (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.
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+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 (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 (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 (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.
+ */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+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 */
+  if (G_UNLIKELY (stop != -1 && stop != start && 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;
+}