gstbasesink.c

gnash 在pc和嵌入式下开发需要的源码

        sstart = sstop = priv->current_sstop;
        rstart = rstop = priv->eos_rtime;
        *do_sync = rstart != -1;
        GST_DEBUG_OBJECT (basesink, "sync times for EOS %" GST_TIME_FORMAT,
            GST_TIME_ARGS (rstart));
        goto done;
        /* other events do not need syncing */
        /* FIXME, maybe NEWSEGMENT might need synchronisation
         * since the POSITION query depends on accumulated times and
         * we cannot accumulate the current segment before the previous
         * one completed.
         */
      default:
        return FALSE;
    }
  }

  /* else do buffer sync code */
  buffer = GST_BUFFER_CAST (obj);

  bclass = GST_BASE_SINK_GET_CLASS (basesink);

  /* just get the times to see if we need syncing */
  if (bclass->get_times)
    bclass->get_times (basesink, buffer, &start, &stop);

  if (start == -1) {
    gst_base_sink_get_times (basesink, buffer, &start, &stop);
    *do_sync = FALSE;
  } else {
    *do_sync = TRUE;
  }

  GST_DEBUG_OBJECT (basesink, "got times start: %" GST_TIME_FORMAT
      ", stop: %" GST_TIME_FORMAT ", do_sync %d", GST_TIME_ARGS (start),
      GST_TIME_ARGS (stop), *do_sync);

  /* collect segment and format for code clarity */
  format = segment->format;

  /* no timestamp clipping if we did not * get a TIME segment format */
  if (G_UNLIKELY (format != GST_FORMAT_TIME)) {
    cstart = start;
    cstop = stop;
    /* do running and stream time in TIME format */
    format = GST_FORMAT_TIME;
    goto do_times;
  }

  /* clip */
  if (G_UNLIKELY (!gst_segment_clip (segment, GST_FORMAT_TIME,
              (gint64) start, (gint64) stop, &cstart, &cstop)))
    goto out_of_segment;

  if (G_UNLIKELY (start != cstart || stop != cstop)) {
    GST_DEBUG_OBJECT (basesink, "clipped to: start %" GST_TIME_FORMAT
        ", stop: %" GST_TIME_FORMAT, GST_TIME_ARGS (cstart),
        GST_TIME_ARGS (cstop));
  }

  /* set last stop position */
  gst_segment_set_last_stop (segment, GST_FORMAT_TIME, cstop);

do_times:
  /* this can produce wrong values if we accumulated non-TIME segments. If this happens,
   * upstream is behaving very badly */
  sstart = gst_segment_to_stream_time (segment, format, cstart);
  sstop = gst_segment_to_stream_time (segment, format, cstop);
  rstart = gst_segment_to_running_time (segment, format, cstart);
  rstop = gst_segment_to_running_time (segment, format, cstop);

done:
  /* save times */
  *rsstart = sstart;
  *rsstop = sstop;
  *rrstart = rstart;
  *rrstop = rstop;

  /* buffers and EOS always need syncing and preroll */
  return TRUE;

  /* special cases */
out_of_segment:
  {
    /* should not happen since we clip them in the chain function already, 
     * we return FALSE so that we don't try to sync on it. */
    GST_ELEMENT_WARNING (basesink, STREAM, FAILED,
        (NULL), ("unexpected buffer out of segment found."));
    GST_LOG_OBJECT (basesink, "buffer skipped, not in segment");
    return FALSE;
  }
}

/* with STREAM_LOCK, PREROLL_LOCK
 *
 * Waits for the clock to reach @time. If @time is not valid, no
 * synchronisation is done and BADTIME is returned. 
 * If synchronisation is disabled in the element or there is no
 * clock, no synchronisation is done and BADTIME is returned.
 *
 * Else a blocking wait is performed on the clock. We save the ClockID
 * so we can unlock the entry at any time. While we are blocking, we 
 * release the PREROLL_LOCK so that other threads can interrupt the entry.
 *
 * @time is expressed in running time.
 */
static GstClockReturn
gst_base_sink_wait_clock (GstBaseSink * basesink, GstClockTime time,
    GstClockTimeDiff * jitter)
{
  GstClockID id;
  GstClockReturn ret;
  GstClock *clock;
  GstClockTimeDiff ts_offset;

  if (G_UNLIKELY (!GST_CLOCK_TIME_IS_VALID (time)))
    goto invalid_time;

  GST_OBJECT_LOCK (basesink);
  if (G_UNLIKELY (!basesink->sync))
    goto no_sync;

  if (G_UNLIKELY ((clock = GST_ELEMENT_CLOCK (basesink)) == NULL))
    goto no_clock;

  /* add base time and latency */
  time += GST_ELEMENT_CAST (basesink)->base_time;
  time += basesink->priv->latency;

  /* apply offset, be carefull for underflows */
  ts_offset = basesink->priv->ts_offset;
  if (ts_offset < 0) {
    ts_offset = -ts_offset;
    if (ts_offset < time)
      time -= ts_offset;
    else
      time = 0;
  } else
    time += ts_offset;

  id = gst_clock_new_single_shot_id (clock, time);
  GST_OBJECT_UNLOCK (basesink);

  basesink->clock_id = id;
  /* release the preroll lock while waiting */
  GST_PAD_PREROLL_UNLOCK (basesink->sinkpad);

  ret = gst_clock_id_wait (id, jitter);

  GST_PAD_PREROLL_LOCK (basesink->sinkpad);
  gst_clock_id_unref (id);
  basesink->clock_id = NULL;

  return ret;

  /* no syncing needed */
invalid_time:
  {
    GST_DEBUG_OBJECT (basesink, "time not valid, no sync needed");
    return GST_CLOCK_BADTIME;
  }
no_sync:
  {
    GST_DEBUG_OBJECT (basesink, "sync disabled");
    GST_OBJECT_UNLOCK (basesink);
    return GST_CLOCK_BADTIME;
  }
no_clock:
  {
    GST_DEBUG_OBJECT (basesink, "no clock, can't sync");
    GST_OBJECT_UNLOCK (basesink);
    return GST_CLOCK_BADTIME;
  }
}

/**
 * gst_base_sink_wait_preroll:
 * @sink: the sink
 *
 * If the #GstBaseSinkClass::render method performs its own synchronisation against
 * the clock it must unblock when going from PLAYING to the PAUSED state and call
 * this method before continuing to render the remaining data.
 *
 * This function will block until a state change to PLAYING happens (in which
 * case this function returns #GST_FLOW_OK) or the processing must be stopped due
 * to a state change to READY or a FLUSH event (in which case this function
 * returns #GST_FLOW_WRONG_STATE).
 *
 * Since: 0.10.11
 *
 * Returns: #GST_FLOW_OK if the preroll completed and processing can
 * continue. Any other return value should be returned from the render vmethod.
 */
GstFlowReturn
gst_base_sink_wait_preroll (GstBaseSink * sink)
{
  sink->have_preroll = TRUE;
  GST_DEBUG_OBJECT (sink, "waiting in preroll for flush or PLAYING");
  /* block until the state changes, or we get a flush, or something */
  GST_PAD_PREROLL_WAIT (sink->sinkpad);
  sink->have_preroll = FALSE;
  if (G_UNLIKELY (sink->flushing))
    goto stopping;
  GST_DEBUG_OBJECT (sink, "continue after preroll");

  return GST_FLOW_OK;

  /* ERRORS */
stopping:
  {
    GST_DEBUG_OBJECT (sink, "preroll interrupted");
    return GST_FLOW_WRONG_STATE;
  }
}

/**
 * gst_base_sink_wait_eos:
 * @sink: the sink
 * @time: the running_time to be reached
 * @jitter: the jitter to be filled with time diff (can be NULL)
 *
 * This function will block until @time is reached. It is usually called by
 * subclasses that use their own internal synchronisation but want to let the
 * EOS be handled by the base class.
 *
 * This function should only be called with the PREROLL_LOCK held, like when
 * receiving an EOS event in the ::event vmethod.
 *
 * Since 0.10.15
 *
 * Returns: #GstFlowReturn
 */
GstFlowReturn
gst_base_sink_wait_eos (GstBaseSink * sink, GstClockTime time,
    GstClockTimeDiff * jitter)
{
  GstClockReturn status;
  GstFlowReturn ret;

  do {
    GST_DEBUG_OBJECT (sink, "checking preroll");

    /* first wait for the playing state before we can continue */
    if (G_UNLIKELY (sink->need_preroll)) {
      ret = gst_base_sink_wait_preroll (sink);
      if (ret != GST_FLOW_OK)
        goto flushing;
    }

    /* preroll done, we can sync since we are in PLAYING now. */
    GST_DEBUG_OBJECT (sink, "possibly waiting for clock to reach %"
        GST_TIME_FORMAT, GST_TIME_ARGS (time));

    /* wait for the clock, this can be interrupted because we got shut down or 
     * we PAUSED. */
    status = gst_base_sink_wait_clock (sink, time, jitter);

    GST_DEBUG_OBJECT (sink, "clock returned %d", status);

    /* invalid time, no clock or sync disabled, just continue then */
    if (status == GST_CLOCK_BADTIME)
      break;

    /* waiting could have been interrupted and we can be flushing now */
    if (G_UNLIKELY (sink->flushing))
      goto flushing;

    /* retry if we got unscheduled, which means we did not reach the timeout
     * yet. if some other error occures, we continue. */
  } while (status == GST_CLOCK_UNSCHEDULED);

  GST_DEBUG_OBJECT (sink, "end of stream");

  return GST_FLOW_OK;

  /* ERRORS */
flushing:
  {
    GST_DEBUG_OBJECT (sink, "we are flushing");
    return GST_FLOW_WRONG_STATE;
  }
}

/* with STREAM_LOCK, PREROLL_LOCK
 *
 * Make sure we are in PLAYING and synchronize an object to the clock.
 *
 * If we need preroll, we are not in PLAYING. We try to commit the state
 * if needed and then block if we still are not PLAYING.
 *
 * We start waiting on the clock in PLAYING. If we got interrupted, we
 * immediatly try to re-preroll.
 *
 * Some objects do not need synchronisation (most events) and so this function
 * immediatly returns GST_FLOW_OK.
 *
 * for objects that arrive later than max-lateness to be synchronized to the 
 * clock have the @late boolean set to TRUE.
 *
 * This function keeps a running average of the jitter (the diff between the
 * clock time and the requested sync time). The jitter is negative for
 * objects that arrive in time and positive for late buffers.
 *
 * does not take ownership of obj.
 */
static GstFlowReturn
gst_base_sink_do_sync (GstBaseSink * basesink, GstPad * pad,
    GstMiniObject * obj, gboolean * late)
{
  GstClockTimeDiff jitter;
  gboolean syncable;
  GstClockReturn status = GST_CLOCK_OK;
  GstClockTime rstart, rstop, sstart, sstop;
  gboolean do_sync;
  GstBaseSinkPrivate *priv;

  priv = basesink->priv;

  sstart = sstop = rstart = rstop = -1;
  do_sync = TRUE;

  priv->current_rstart = -1;

  /* get timing information for this object against the render segment */
  syncable = gst_base_sink_get_sync_times (basesink, obj,
      &sstart, &sstop, &rstart, &rstop, &do_sync, &basesink->segment);

  /* a syncable object needs to participate in preroll and
   * clocking. All buffers and EOS are syncable. */
  if (G_UNLIKELY (!syncable))
    goto not_syncable;

  /* store timing info for current object */
  priv->current_rstart = rstart;
  priv->current_rstop = (rstop != -1 ? rstop : rstart);
  /* save sync time for eos when the previous object needed sync */
  priv->eos_rtime = (do_sync ? priv->current_rstop : -1);

again:
  /* first do preroll, this makes sure we commit our state
   * to PAUSED and can continue to PLAYING. We cannot perform
   * any clock sync in PAUSED because there is no clock. 
   */
  while (G_UNLIKELY (basesink->need_preroll)) {
    GST_DEBUG_OBJECT (basesink, "prerolling object %p", obj);

    if (G_LIKELY (basesink->playing_async)) {
      /* commit state */
      if (G_UNLIKELY (!gst_base_sink_commit_state (basesink)))
        goto stopping;
    }

    /* need to recheck here because the commit state could have
     * made us not need the preroll anymore */
    if (G_LIKELY (basesink->need_preroll)) {
      /* block until the state changes, or we get a flush, or something */
      if (gst_base_sink_wait_preroll (basesink) != GST_FLOW_OK)
        goto flushing;
    }
  }

  /* After rendering we store the position of the last buffer so that we can use
   * it to report the position. We need to take the lock here. */
  GST_OBJECT_LOCK (basesink);
  priv->current_sstart = sstart;
  priv->current_sstop = (sstop != -1 ? sstop : sstart);
  GST_OBJECT_UNLOCK (basesink);

  if (!do_sync)
    goto done;

  /* preroll done, we can sync since we are in PLAYING now. */
  GST_DEBUG_OBJECT (basesink, "possibly waiting for clock to reach %"
      GST_TIME_FORMAT, GST_TIME_ARGS (rstart));

  /* this function will return immediatly if start == -1, no clock
   * or sync is disabled with GST_CLOCK_BADTIME. */
  status = gst_base_sink_wait_clock (basesink, rstart, &jitter);

  GST_DEBUG_OBJECT (basesink, "clock returned %d", status);

  /* invalid time, no clock or sync disabled, just render */
  if (status == GST_CLOCK_BADTIME)
    goto done;

  /* waiting could have been interrupted and we can be flushing now */
  if (G_UNLIKELY (basesink->flushing))
    goto flushing;

  /* check for unlocked by a state change, we are not flushing so
   * we can try to preroll on the current buffer. */
  if (G_UNLIKELY (status == GST_CLOCK_UNSCHEDULED)) {
    GST_DEBUG_OBJECT (basesink, "unscheduled, waiting some more");
    goto again;
  }

  /* successful syncing done, record observation */
  priv->current_jitter = jitter;

  /* check if the object should be dropped */
  *late = gst_base_sink_is_too_late (basesink, obj, rstart, rstop,
      status, jitter);

done:
  return GST_FLOW_OK;

  /* ERRORS */
not_syncable:
  {
    GST_DEBUG_OBJECT (basesink, "non syncable object %p", obj);
    return GST_FLOW_OK;
  }
flushing:
  {
    GST_DEBUG_OBJECT (basesink, "we are flushing");
    return GST_FLOW_WRONG_STATE;
  }
stopping:
  {
    GST_DEBUG_OBJECT (basesink, "stopping while commiting state");
    return GST_FLOW_WRONG_STATE;
  }
}

static gboolean
gst_base_sink_send_qos (GstBaseSink * basesink,
    gdouble proportion, GstClockTime time, GstClockTimeDiff diff)
{
  GstEvent *event;
  gboolean res;

  /* generate Quality-of-Service event */
  GST_CAT_DEBUG_OBJECT (GST_CAT_QOS, basesink,
      "qos: proportion: %lf, diff %" G_GINT64_FORMAT ", timestamp %"
      GST_TIME_FORMAT, proportion, diff, GST_TIME_ARGS (time));