/* GStreamer

 * Copyright (C) 2010 Sebastian Dröge <sebastian.droege@collabora.co.uk>

 *

 * 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., 51 Franklin St, Fifth Floor,

 * Boston, MA 02110-1301, USA.

 */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include "gststreamsynchronizer.h"

GST_DEBUG_CATEGORY_STATIC (stream_synchronizer_debug);

#define GST_CAT_DEFAULT stream_synchronizer_debug

#define GST_STREAM_SYNCHRONIZER_LOCK(obj) G_STMT_START {                \

    GST_TRACE_OBJECT (obj,                                              \

                    "locking from thread %p",                           \

                    g_thread_self ());                                  \

    g_mutex_lock (&GST_STREAM_SYNCHRONIZER_CAST(obj)->lock);            \

    GST_TRACE_OBJECT (obj,                                              \

                    "locked from thread %p",                            \

                    g_thread_self ());                                  \

} G_STMT_END

#define GST_STREAM_SYNCHRONIZER_UNLOCK(obj) G_STMT_START {              \

    GST_TRACE_OBJECT (obj,                                              \

                    "unlocking from thread %p",                         \

                    g_thread_self ());                                  \

    g_mutex_unlock (&GST_STREAM_SYNCHRONIZER_CAST(obj)->lock);              \

} G_STMT_END

static GstStaticPadTemplate srctemplate = GST_STATIC_PAD_TEMPLATE ("src_%u",

    GST_PAD_SRC,

    GST_PAD_SOMETIMES,

    GST_STATIC_CAPS_ANY);

static GstStaticPadTemplate sinktemplate = GST_STATIC_PAD_TEMPLATE ("sink_%u",

    GST_PAD_SINK,

    GST_PAD_REQUEST,

    GST_STATIC_CAPS_ANY);

#define gst_stream_synchronizer_parent_class parent_class

G_DEFINE_TYPE (GstStreamSynchronizer, gst_stream_synchronizer,

    GST_TYPE_ELEMENT);

typedef struct

{

  GstStreamSynchronizer *transform;

  guint stream_number;

  GstPad *srcpad;

  GstPad *sinkpad;

  GstSegment segment;

  gboolean wait;                /* TRUE if waiting/blocking */

  gboolean is_eos;              /* TRUE if EOS was received */

  gboolean eos_sent;            /* when EOS was sent downstream */

  gboolean flushing;            /* set after flush-start and before flush-stop */

  gboolean seen_data;

  gboolean send_gap_event;

  GstClockTime gap_duration;

  GstStreamFlags flags;

  GCond stream_finish_cond;

  /* seqnum of the previously received STREAM_START

   * default: G_MAXUINT32 */

  guint32 stream_start_seqnum;

  guint32 segment_seqnum;

  guint group_id;

} GstSyncStream;

/* Must be called with lock! */

static inline GstPad *

gst_stream_get_other_pad (GstSyncStream * stream, GstPad * pad)

{

  if (stream->sinkpad == pad)

    return gst_object_ref (stream->srcpad);

  if (stream->srcpad == pad)

    return gst_object_ref (stream->sinkpad);

  return NULL;

}

static GstPad *

gst_stream_get_other_pad_from_pad (GstStreamSynchronizer * self, GstPad * pad)

{

  GstSyncStream *stream;

  GstPad *opad = NULL;

  GST_STREAM_SYNCHRONIZER_LOCK (self);

  stream = gst_pad_get_element_private (pad);

  if (!stream)

    goto out;

  opad = gst_stream_get_other_pad (stream, pad);

out:

  GST_STREAM_SYNCHRONIZER_UNLOCK (self);

  if (!opad)

    GST_WARNING_OBJECT (pad, "Trying to get other pad after releasing");

  return opad;

}

/* Generic pad functions */

static GstIterator *

gst_stream_synchronizer_iterate_internal_links (GstPad * pad,

    GstObject * parent)

{

  GstIterator *it = NULL;

  GstPad *opad;

  opad =

      gst_stream_get_other_pad_from_pad (GST_STREAM_SYNCHRONIZER (parent), pad);

  if (opad) {

    GValue value = { 0, };

    g_value_init (&value, GST_TYPE_PAD);

    g_value_set_object (&value, opad);

    it = gst_iterator_new_single (GST_TYPE_PAD, &value);

    g_value_unset (&value);

    gst_object_unref (opad);

  }

  return it;

}

/* srcpad functions */

static gboolean

gst_stream_synchronizer_src_event (GstPad * pad, GstObject * parent,

    GstEvent * event)

{

  GstStreamSynchronizer *self = GST_STREAM_SYNCHRONIZER (parent);

  gboolean ret = FALSE;

  GST_LOG_OBJECT (pad, "Handling event %s: %" GST_PTR_FORMAT,

      GST_EVENT_TYPE_NAME (event), event);

  switch (GST_EVENT_TYPE (event)) {

    case GST_EVENT_QOS:{

      gdouble proportion;

      GstClockTimeDiff diff;

      GstClockTime timestamp;

      gint64 running_time_diff = -1;

      GstSyncStream *stream;

      gst_event_parse_qos (event, NULL, &proportion, &diff, &timestamp);

      gst_event_unref (event);

      GST_STREAM_SYNCHRONIZER_LOCK (self);

      stream = gst_pad_get_element_private (pad);

      if (stream)

        running_time_diff = stream->segment.base;

      GST_STREAM_SYNCHRONIZER_UNLOCK (self);

      if (running_time_diff == -1) {

        GST_WARNING_OBJECT (pad, "QOS event before group start");

        goto out;

      }

      if (timestamp < running_time_diff) {

        GST_DEBUG_OBJECT (pad, "QOS event from previous group");

        goto out;

      }

      GST_LOG_OBJECT (pad,

          "Adjusting QOS event: %" GST_TIME_FORMAT " - %" GST_TIME_FORMAT " = %"

          GST_TIME_FORMAT, GST_TIME_ARGS (timestamp),

          GST_TIME_ARGS (running_time_diff),

          GST_TIME_ARGS (timestamp - running_time_diff));

      timestamp -= running_time_diff;

      /* That case is invalid for QoS events */

      if (diff < 0 && -diff > timestamp) {

        GST_DEBUG_OBJECT (pad, "QOS event from previous group");

        ret = TRUE;

        goto out;

      }

      event =

          gst_event_new_qos (GST_QOS_TYPE_UNDERFLOW, proportion, diff,

          timestamp);

      break;

    }

    default:

      break;

  }

  ret = gst_pad_event_default (pad, parent, event);

out:

  return ret;

}

/* must be called with the STREAM_SYNCHRONIZER_LOCK */

static gboolean

gst_stream_synchronizer_wait (GstStreamSynchronizer * self, GstPad * pad)

{

  gboolean ret = FALSE;

  GstSyncStream *stream;

  while (!self->eos && !self->flushing) {

    stream = gst_pad_get_element_private (pad);

    if (!stream) {

      GST_WARNING_OBJECT (pad, "unknown stream");

      return ret;

    }

    if (stream->flushing) {

      GST_DEBUG_OBJECT (pad, "Flushing");

      break;

    }

    if (!stream->wait) {

      GST_DEBUG_OBJECT (pad, "Stream not waiting anymore");

      break;

    }

    if (stream->send_gap_event) {

      GstEvent *event;

      if (!GST_CLOCK_TIME_IS_VALID (stream->segment.position)) {

        GST_WARNING_OBJECT (pad, "Have no position and can't send GAP event");

        stream->send_gap_event = FALSE;

        continue;

      }

      event =

          gst_event_new_gap (stream->segment.position, stream->gap_duration);

      GST_DEBUG_OBJECT (pad,

          "Send GAP event, position: %" GST_TIME_FORMAT " duration: %"

          GST_TIME_FORMAT, GST_TIME_ARGS (stream->segment.position),

          GST_TIME_ARGS (stream->gap_duration));

      /* drop lock when sending GAP event, which may block in e.g. preroll */

      GST_STREAM_SYNCHRONIZER_UNLOCK (self);

      ret = gst_pad_push_event (pad, event);

      GST_STREAM_SYNCHRONIZER_LOCK (self);

      if (!ret) {

        return ret;

      }

      stream->send_gap_event = FALSE;

      /* force a check on the loop conditions as we unlocked a

       * few lines above and those variables could have changed */

      continue;

    }

    g_cond_wait (&stream->stream_finish_cond, &self->lock);

  }

  return TRUE;

}

/* sinkpad functions */

static gboolean

gst_stream_synchronizer_sink_event (GstPad * pad, GstObject * parent,

    GstEvent * event)

{

  GstStreamSynchronizer *self = GST_STREAM_SYNCHRONIZER (parent);

  gboolean ret = FALSE;

  GST_LOG_OBJECT (pad, "Handling event %s: %" GST_PTR_FORMAT,

      GST_EVENT_TYPE_NAME (event), event);

  switch (GST_EVENT_TYPE (event)) {

    case GST_EVENT_STREAM_START:

    {

      GstSyncStream *stream, *ostream;

      guint32 seqnum = gst_event_get_seqnum (event);

      guint group_id;

      gboolean have_group_id;

      GList *l;

      gboolean all_wait = TRUE;

      gboolean new_stream = TRUE;

      have_group_id = gst_event_parse_group_id (event, &group_id);

      GST_STREAM_SYNCHRONIZER_LOCK (self);

      self->have_group_id &= have_group_id;

      have_group_id = self->have_group_id;

      stream = gst_pad_get_element_private (pad);

      if (!stream) {

        GST_DEBUG_OBJECT (self, "No stream or STREAM_START from same source");

        GST_STREAM_SYNCHRONIZER_UNLOCK (self);

        break;

      }

      gst_event_parse_stream_flags (event, &stream->flags);

      if ((have_group_id && stream->group_id != group_id) || (!have_group_id

              && stream->stream_start_seqnum != seqnum)) {

        stream->is_eos = FALSE;

        stream->eos_sent = FALSE;

        stream->flushing = FALSE;

        stream->stream_start_seqnum = seqnum;

        stream->group_id = group_id;

        if (!have_group_id) {

          /* Check if this belongs to a stream that is already there,

           * e.g. we got the visualizations for an audio stream */

          for (l = self->streams; l; l = l->next) {

            ostream = l->data;

            if (ostream != stream && ostream->stream_start_seqnum == seqnum

                && !ostream->wait) {

              new_stream = FALSE;

              break;

            }

          }

          if (!new_stream) {

            GST_DEBUG_OBJECT (pad,

                "Stream %d belongs to running stream %d, no waiting",

                stream->stream_number, ostream->stream_number);

            stream->wait = FALSE;

            GST_STREAM_SYNCHRONIZER_UNLOCK (self);

            break;

          }

        } else if (group_id == self->group_id) {

          GST_DEBUG_OBJECT (pad, "Stream %d belongs to running group %d, "

              "no waiting", stream->stream_number, group_id);

          GST_STREAM_SYNCHRONIZER_UNLOCK (self);

          break;

        }

        GST_DEBUG_OBJECT (pad, "Stream %d changed", stream->stream_number);

        stream->wait = TRUE;

        for (l = self->streams; l; l = l->next) {

          GstSyncStream *ostream = l->data;

          all_wait = all_wait && ((ostream->flags & GST_STREAM_FLAG_SPARSE)

              || (ostream->wait && (!have_group_id

                      || ostream->group_id == group_id)));

          if (!all_wait)

            break;

        }

        if (all_wait) {

          gint64 position = 0;

          if (have_group_id)

            GST_DEBUG_OBJECT (self,

                "All streams have changed to group id %u -- unblocking",

                group_id);

          else

            GST_DEBUG_OBJECT (self, "All streams have changed -- unblocking");

          self->group_id = group_id;

          for (l = self->streams; l; l = l->next) {

            GstSyncStream *ostream = l->data;

            gint64 stop_running_time;

            gint64 position_running_time;

            ostream->wait = FALSE;

            if (ostream->segment.format == GST_FORMAT_TIME) {

              if (ostream->segment.rate > 0)

                stop_running_time =

                    gst_segment_to_running_time (&ostream->segment,

                    GST_FORMAT_TIME, ostream->segment.stop);

              else

                stop_running_time =

                    gst_segment_to_running_time (&ostream->segment,

                    GST_FORMAT_TIME, ostream->segment.start);

              position_running_time =

                  gst_segment_to_running_time (&ostream->segment,

                  GST_FORMAT_TIME, ostream->segment.position);

              position_running_time =

                  MAX (position_running_time, stop_running_time);

              if (ostream->segment.rate > 0)

                position_running_time -=

                    gst_segment_to_running_time (&ostream->segment,

                    GST_FORMAT_TIME, ostream->segment.start);

              else

                position_running_time -=

                    gst_segment_to_running_time (&ostream->segment,

                    GST_FORMAT_TIME, ostream->segment.stop);

              position_running_time = MAX (0, position_running_time);

              position = MAX (position, position_running_time);

            }

          }

          self->group_start_time += position;

          GST_DEBUG_OBJECT (self, "New group start time: %" GST_TIME_FORMAT,

              GST_TIME_ARGS (self->group_start_time));

          for (l = self->streams; l; l = l->next) {

            GstSyncStream *ostream = l->data;

            ostream->wait = FALSE;

            g_cond_broadcast (&ostream->stream_finish_cond);

          }

        }

      }

      GST_STREAM_SYNCHRONIZER_UNLOCK (self);

      break;

    }

    case GST_EVENT_SEGMENT:{

      GstSyncStream *stream;

      GstSegment segment;

      gst_event_copy_segment (event, &segment);

      GST_STREAM_SYNCHRONIZER_LOCK (self);

      gst_stream_synchronizer_wait (self, pad);

      if (self->shutdown) {

        GST_STREAM_SYNCHRONIZER_UNLOCK (self);

        gst_event_unref (event);

        goto done;

      }

      stream = gst_pad_get_element_private (pad);

      if (stream && segment.format == GST_FORMAT_TIME) {

        GST_DEBUG_OBJECT (pad,

            "New stream, updating base from %" GST_TIME_FORMAT " to %"

            GST_TIME_FORMAT, GST_TIME_ARGS (segment.base),

            GST_TIME_ARGS (segment.base + self->group_start_time));

        segment.base += self->group_start_time;

        GST_DEBUG_OBJECT (pad, "Segment was: %" GST_SEGMENT_FORMAT,

            &stream->segment);

        gst_segment_copy_into (&segment, &stream->segment);

        GST_DEBUG_OBJECT (pad, "Segment now is: %" GST_SEGMENT_FORMAT,

            &stream->segment);

        stream->segment_seqnum = gst_event_get_seqnum (event);

        GST_DEBUG_OBJECT (pad, "Stream start running time: %" GST_TIME_FORMAT,

            GST_TIME_ARGS (stream->segment.base));

        {

          GstEvent *tmpev;

          tmpev = gst_event_new_segment (&stream->segment);

          gst_event_set_seqnum (tmpev, stream->segment_seqnum);

          gst_event_unref (event);

          event = tmpev;

        }

      } else if (stream) {

        GST_WARNING_OBJECT (pad, "Non-TIME segment: %s",

            gst_format_get_name (segment.format));

        gst_segment_init (&stream->segment, GST_FORMAT_UNDEFINED);

      }

      GST_STREAM_SYNCHRONIZER_UNLOCK (self);

      break;

    }

    case GST_EVENT_FLUSH_START:{

      GstSyncStream *stream;

      GST_STREAM_SYNCHRONIZER_LOCK (self);

      stream = gst_pad_get_element_private (pad);

      self->eos = FALSE;

      if (stream) {

        GST_DEBUG_OBJECT (pad, "Flushing streams");

        stream->flushing = TRUE;

        g_cond_broadcast (&stream->stream_finish_cond);

      }

      GST_STREAM_SYNCHRONIZER_UNLOCK (self);

      break;

    }

    case GST_EVENT_FLUSH_STOP:{

      GstSyncStream *stream;

      GList *l;

      GstClockTime new_group_start_time = 0;

      GST_STREAM_SYNCHRONIZER_LOCK (self);

      stream = gst_pad_get_element_private (pad);

      if (stream) {

        GST_DEBUG_OBJECT (pad, "Resetting segment for stream %d",

            stream->stream_number);

        gst_segment_init (&stream->segment, GST_FORMAT_UNDEFINED);

        stream->is_eos = FALSE;

        stream->eos_sent = FALSE;

        stream->flushing = FALSE;

        stream->wait = FALSE;

        g_cond_broadcast (&stream->stream_finish_cond);

      }

      for (l = self->streams; l; l = l->next) {

        GstSyncStream *ostream = l->data;

        GstClockTime start_running_time;

        if (ostream == stream || ostream->flushing)

          continue;

        if (ostream->segment.format == GST_FORMAT_TIME) {

          if (ostream->segment.rate > 0)

            start_running_time =

                gst_segment_to_running_time (&ostream->segment,

                GST_FORMAT_TIME, ostream->segment.start);

          else

            start_running_time =

                gst_segment_to_running_time (&ostream->segment,

                GST_FORMAT_TIME, ostream->segment.stop);

          new_group_start_time = MAX (new_group_start_time, start_running_time);

        }

      }

      GST_DEBUG_OBJECT (pad,

          "Updating group start time from %" GST_TIME_FORMAT " to %"

          GST_TIME_FORMAT, GST_TIME_ARGS (self->group_start_time),

          GST_TIME_ARGS (new_group_start_time));

      self->group_start_time = new_group_start_time;

      GST_STREAM_SYNCHRONIZER_UNLOCK (self);

      break;

    }

      /* unblocking EOS wait when track switch. */

    case GST_EVENT_CUSTOM_DOWNSTREAM_OOB:{

      if (gst_event_has_name (event, "playsink-custom-video-flush")

          || gst_event_has_name (event, "playsink-custom-audio-flush")

          || gst_event_has_name (event, "playsink-custom-subtitle-flush")) {

        GstSyncStream *stream;

        GST_STREAM_SYNCHRONIZER_LOCK (self);

        stream = gst_pad_get_element_private (pad);

        if (stream) {

          stream->is_eos = FALSE;

          stream->eos_sent = FALSE;

          stream->wait = FALSE;

          g_cond_broadcast (&stream->stream_finish_cond);

        }

        GST_STREAM_SYNCHRONIZER_UNLOCK (self);

      }

      break;

    }

    case GST_EVENT_EOS:{

      GstSyncStream *stream;

      GList *l;

      gboolean all_eos = TRUE;

      gboolean seen_data;

      GSList *pads = NULL;

      GstPad *srcpad;

      GstClockTime timestamp;

      GST_STREAM_SYNCHRONIZER_LOCK (self);

      stream = gst_pad_get_element_private (pad);

      if (!stream) {

        GST_STREAM_SYNCHRONIZER_UNLOCK (self);

        GST_WARNING_OBJECT (pad, "EOS for unknown stream");

        break;

      }

      GST_DEBUG_OBJECT (pad, "Have EOS for stream %d", stream->stream_number);

      stream->is_eos = TRUE;

      seen_data = stream->seen_data;

      srcpad = gst_object_ref (stream->srcpad);

      if (seen_data && stream->segment.position != -1)

        timestamp = stream->segment.position;

      else if (stream->segment.rate < 0.0 || stream->segment.stop == -1)

        timestamp = stream->segment.start;

      else

        timestamp = stream->segment.stop;

      stream->segment.position = timestamp;

      for (l = self->streams; l; l = l->next) {

        GstSyncStream *ostream = l->data;

        all_eos = all_eos && ostream->is_eos;

        if (!all_eos)

          break;

      }

      if (all_eos) {

        GST_DEBUG_OBJECT (self, "All streams are EOS -- forwarding");

        self->eos = TRUE;

        for (l = self->streams; l; l = l->next) {

          GstSyncStream *ostream = l->data;

          /* local snapshot of current pads */

          gst_object_ref (ostream->srcpad);

          pads = g_slist_prepend (pads, ostream->srcpad);

        }

      }

      if (pads) {

        GstPad *pad;

        GSList *epad;

        GstSyncStream *ostream;

        ret = TRUE;

        epad = pads;

        while (epad) {

          pad = epad->data;

          ostream = gst_pad_get_element_private (pad);

          if (ostream) {

            g_cond_broadcast (&ostream->stream_finish_cond);

          }

          gst_object_unref (pad);

          epad = g_slist_next (epad);

        }

        g_slist_free (pads);

      } else {

        if (seen_data) {

          stream->send_gap_event = TRUE;

          stream->gap_duration = GST_CLOCK_TIME_NONE;

          stream->wait = TRUE;

          ret = gst_stream_synchronizer_wait (self, srcpad);

        }

      }

      /* send eos if haven't seen data. seen_data will be true if data buffer

       * of the track have received in anytime. sink is ready if seen_data is

       * true, so can send GAP event. Will send EOS if sink isn't ready. The

       * scenario for the case is one track haven't any media data and then

       * send EOS. Or no any valid media data in one track, so decoder can't

       * get valid CAPS for the track. sink can't ready without received CAPS.*/

      if (!seen_data || self->eos) {

        GST_DEBUG_OBJECT (pad, "send EOS event");

        /* drop lock when sending eos, which may block in e.g. preroll */

        GST_STREAM_SYNCHRONIZER_UNLOCK (self);

        ret = gst_pad_push_event (srcpad, gst_event_new_eos ());

        GST_STREAM_SYNCHRONIZER_LOCK (self);

        stream = gst_pad_get_element_private (pad);

        if (stream) {

          stream->eos_sent = TRUE;

        }

      }

      gst_object_unref (srcpad);

      gst_event_unref (event);

      GST_STREAM_SYNCHRONIZER_UNLOCK (self);

      goto done;

    }

    default:

      break;

  }

  ret = gst_pad_event_default (pad, parent, event);

done:

  return ret;

}

static GstFlowReturn

gst_stream_synchronizer_sink_chain (GstPad * pad, GstObject * parent,

    GstBuffer * buffer)

{

  GstStreamSynchronizer *self = GST_STREAM_SYNCHRONIZER (parent);

  GstPad *opad;

  GstFlowReturn ret = GST_FLOW_ERROR;

  GstSyncStream *stream;

  GstClockTime duration = GST_CLOCK_TIME_NONE;

  GstClockTime timestamp = GST_CLOCK_TIME_NONE;

  GstClockTime timestamp_end = GST_CLOCK_TIME_NONE;

  GST_LOG_OBJECT (pad, "Handling buffer %p: size=%" G_GSIZE_FORMAT

      ", timestamp=%" GST_TIME_FORMAT " duration=%" GST_TIME_FORMAT

      " offset=%" G_GUINT64_FORMAT " offset_end=%" G_GUINT64_FORMAT,

      buffer, gst_buffer_get_size (buffer),

      GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (buffer)),

      GST_TIME_ARGS (GST_BUFFER_DURATION (buffer)),

      GST_BUFFER_OFFSET (buffer), GST_BUFFER_OFFSET_END (buffer));

  timestamp = GST_BUFFER_TIMESTAMP (buffer);

  duration = GST_BUFFER_DURATION (buffer);

  if (GST_CLOCK_TIME_IS_VALID (timestamp)

      && GST_CLOCK_TIME_IS_VALID (duration))

    timestamp_end = timestamp + duration;

  GST_STREAM_SYNCHRONIZER_LOCK (self);

  stream = gst_pad_get_element_private (pad);

  if (stream) {

    stream->seen_data = TRUE;

    if (stream->segment.format == GST_FORMAT_TIME

        && GST_CLOCK_TIME_IS_VALID (timestamp)) {

      GST_LOG_OBJECT (pad,

          "Updating position from %" GST_TIME_FORMAT " to %" GST_TIME_FORMAT,

          GST_TIME_ARGS (stream->segment.position), GST_TIME_ARGS (timestamp));

      if (stream->segment.rate > 0.0)

        stream->segment.position = timestamp;

      else

        stream->segment.position = timestamp_end;

    }

  }

  GST_STREAM_SYNCHRONIZER_UNLOCK (self);

  opad = gst_stream_get_other_pad_from_pad (self, pad);

  if (opad) {

    ret = gst_pad_push (opad, buffer);

    gst_object_unref (opad);

  }

  GST_LOG_OBJECT (pad, "Push returned: %s", gst_flow_get_name (ret));

  if (ret == GST_FLOW_OK) {

    GList *l;

    GST_STREAM_SYNCHRONIZER_LOCK (self);

    stream = gst_pad_get_element_private (pad);

    if (stream && stream->segment.format == GST_FORMAT_TIME) {

      GstClockTime position;

      if (stream->segment.rate > 0.0)

        position = timestamp_end;

      else

        position = timestamp;

      if (GST_CLOCK_TIME_IS_VALID (position)) {

        GST_LOG_OBJECT (pad,

            "Updating position from %" GST_TIME_FORMAT " to %" GST_TIME_FORMAT,

            GST_TIME_ARGS (stream->segment.position), GST_TIME_ARGS (position));

        stream->segment.position = position;

      }

    }

    /* Advance EOS streams if necessary. For non-EOS

     * streams the demuxers should already do this! */

    if (!GST_CLOCK_TIME_IS_VALID (timestamp_end) &&

        GST_CLOCK_TIME_IS_VALID (timestamp)) {

      timestamp_end = timestamp + GST_SECOND;

    }

    for (l = self->streams; l; l = l->next) {

      GstSyncStream *ostream = l->data;

      gint64 position;

      if (!ostream->is_eos || ostream->eos_sent ||

          ostream->segment.format != GST_FORMAT_TIME)

        continue;

      if (ostream->segment.position != -1)

        position = ostream->segment.position;

      else

        position = ostream->segment.start;

      /* Is there a 1 second lag? */

      if (position != -1 && GST_CLOCK_TIME_IS_VALID (timestamp_end) &&

          position + GST_SECOND < timestamp_end) {

        gint64 new_start;

        new_start = timestamp_end - GST_SECOND;

        GST_DEBUG_OBJECT (ostream->sinkpad,

            "Advancing stream %u from %" GST_TIME_FORMAT " to %"

            GST_TIME_FORMAT, ostream->stream_number, GST_TIME_ARGS (position),

            GST_TIME_ARGS (new_start));

        ostream->segment.position = new_start;

        ostream->send_gap_event = TRUE;

        ostream->gap_duration = new_start - position;

        g_cond_broadcast (&ostream->stream_finish_cond);

      }

    }

    GST_STREAM_SYNCHRONIZER_UNLOCK (self);

  }

  return ret;

}

/* GstElement vfuncs */

static GstPad *

gst_stream_synchronizer_request_new_pad (GstElement * element,

    GstPadTemplate * temp, const gchar * name, const GstCaps * caps)

{

  GstStreamSynchronizer *self = GST_STREAM_SYNCHRONIZER (element);

  GstSyncStream *stream;

  gchar *tmp;

  GST_STREAM_SYNCHRONIZER_LOCK (self);

  GST_DEBUG_OBJECT (self, "Requesting new pad for stream %d",

      self->current_stream_number);

  stream = g_slice_new0 (GstSyncStream);

  stream->transform = self;

  stream->stream_number = self->current_stream_number;

  g_cond_init (&stream->stream_finish_cond);

  stream->stream_start_seqnum = G_MAXUINT32;

  stream->segment_seqnum = G_MAXUINT32;

  stream->group_id = G_MAXUINT;

  stream->seen_data = FALSE;

  stream->send_gap_event = FALSE;

  tmp = g_strdup_printf ("sink_%u", self->current_stream_number);

  stream->sinkpad = gst_pad_new_from_static_template (&sinktemplate, tmp);

  g_free (tmp);

  gst_pad_set_element_private (stream->sinkpad, stream);

  gst_pad_set_iterate_internal_links_function (stream->sinkpad,

      GST_DEBUG_FUNCPTR (gst_stream_synchronizer_iterate_internal_links));

  gst_pad_set_event_function (stream->sinkpad,

      GST_DEBUG_FUNCPTR (gst_stream_synchronizer_sink_event));

  gst_pad_set_chain_function (stream->sinkpad,

      GST_DEBUG_FUNCPTR (gst_stream_synchronizer_sink_chain));

  GST_PAD_SET_PROXY_CAPS (stream->sinkpad);

  GST_PAD_SET_PROXY_ALLOCATION (stream->sinkpad);

  GST_PAD_SET_PROXY_SCHEDULING (stream->sinkpad);

  tmp = g_strdup_printf ("src_%u", self->current_stream_number);

  stream->srcpad = gst_pad_new_from_static_template (&srctemplate, tmp);

  g_free (tmp);

  gst_pad_set_element_private (stream->srcpad, stream);

  gst_pad_set_iterate_internal_links_function (stream->srcpad,

      GST_DEBUG_FUNCPTR (gst_stream_synchronizer_iterate_internal_links));

  gst_pad_set_event_function (stream->srcpad,

      GST_DEBUG_FUNCPTR (gst_stream_synchronizer_src_event));

  GST_PAD_SET_PROXY_CAPS (stream->srcpad);

  GST_PAD_SET_PROXY_ALLOCATION (stream->srcpad);

  GST_PAD_SET_PROXY_SCHEDULING (stream->srcpad);

  gst_segment_init (&stream->segment, GST_FORMAT_UNDEFINED);

  self->streams = g_list_prepend (self->streams, stream);

  self->current_stream_number++;

  GST_STREAM_SYNCHRONIZER_UNLOCK (self);

  /* Add pads and activate unless we're going to NULL */

  g_rec_mutex_lock (GST_STATE_GET_LOCK (self));

  if (GST_STATE_TARGET (self) != GST_STATE_NULL) {

    gst_pad_set_active (stream->srcpad, TRUE);

    gst_pad_set_active (stream->sinkpad, TRUE);

  }

  gst_element_add_pad (GST_ELEMENT_CAST (self), stream->srcpad);

  gst_element_add_pad (GST_ELEMENT_CAST (self), stream->sinkpad);

  g_rec_mutex_unlock (GST_STATE_GET_LOCK (self));

  return stream->sinkpad;

}

/* Must be called with lock! */

static void

gst_stream_synchronizer_release_stream (GstStreamSynchronizer * self,

    GstSyncStream * stream)

{

  GList *l;

  GST_DEBUG_OBJECT (self, "Releasing stream %d", stream->stream_number);

  for (l = self->streams; l; l = l->next) {

    if (l->data == stream) {

      self->streams = g_list_delete_link (self->streams, l);

      break;

    }

  }

  g_assert (l != NULL);

  if (self->streams == NULL) {

    self->have_group_id = TRUE;

    self->group_id = G_MAXUINT;

  }

  /* we can drop the lock, since stream exists now only local.

   * Moreover, we should drop, to prevent deadlock with STREAM_LOCK

   * (due to reverse lock order) when deactivating pads */

  GST_STREAM_SYNCHRONIZER_UNLOCK (self);

  gst_pad_set_element_private (stream->srcpad, NULL);

  gst_pad_set_element_private (stream->sinkpad, NULL);

  gst_pad_set_active (stream->srcpad, FALSE);

  gst_element_remove_pad (GST_ELEMENT_CAST (self), stream->srcpad);

  gst_pad_set_active (stream->sinkpad, FALSE);