gstbasesrc.c

gnash 在pc和嵌入式下开发需要的源码

       * especially sync since all segment info will get flushed */
      break;

      /* downstream serialized events */
    case GST_EVENT_EOS:
      /* FIXME, queue EOS and make sure the task or pull function 
       * perform the EOS actions. */
      break;
    case GST_EVENT_NEWSEGMENT:
      /* sending random NEWSEGMENT downstream can break sync. */
      break;
    case GST_EVENT_TAG:
      /* sending tags could be useful, FIXME insert in dataflow */
      break;
    case GST_EVENT_BUFFERSIZE:
      /* does not seem to make much sense currently */
      break;

      /* upstream events */
    case GST_EVENT_QOS:
      /* elements should override send_event and do something */
      break;
    case GST_EVENT_SEEK:
    {
      gboolean started;

      GST_OBJECT_LOCK (src->srcpad);
      if (GST_PAD_ACTIVATE_MODE (src->srcpad) == GST_ACTIVATE_PULL)
        goto wrong_mode;
      started = GST_PAD_ACTIVATE_MODE (src->srcpad) == GST_ACTIVATE_PUSH;
      GST_OBJECT_UNLOCK (src->srcpad);

      if (started) {
        /* when we are running in push mode, we can execute the
         * seek right now, we need to unlock. */
        result = gst_base_src_perform_seek (src, event, TRUE);
      } else {
        GstEvent **event_p;

        /* else we store the event and execute the seek when we
         * get activated */
        GST_OBJECT_LOCK (src);
        event_p = &src->data.ABI.pending_seek;
        gst_event_replace ((GstEvent **) event_p, event);
        GST_OBJECT_UNLOCK (src);
        /* assume the seek will work */
        result = TRUE;
      }
      break;
    }
    case GST_EVENT_NAVIGATION:
      /* could make sense for elements that do something with navigation events
       * but then they would need to override the send_event function */
      break;
    case GST_EVENT_LATENCY:
      /* does not seem to make sense currently */
      break;

      /* custom events */
    case GST_EVENT_CUSTOM_UPSTREAM:
      /* override send_event if you want this */
      break;
    case GST_EVENT_CUSTOM_DOWNSTREAM:
    case GST_EVENT_CUSTOM_BOTH:
      /* FIXME, insert event in the dataflow */
      break;
    case GST_EVENT_CUSTOM_DOWNSTREAM_OOB:
    case GST_EVENT_CUSTOM_BOTH_OOB:
      /* insert a random custom event into the pipeline */
      GST_DEBUG_OBJECT (src, "pushing custom OOB event downstream");
      result = gst_pad_push_event (src->srcpad, event);
      /* we gave away the ref to the event in the push */
      event = NULL;
      break;
    default:
      break;
  }
done:
  /* if we still have a ref to the event, unref it now */
  if (event)
    gst_event_unref (event);

  return result;

  /* ERRORS */
wrong_mode:
  {
    GST_DEBUG_OBJECT (src, "cannot perform seek when operating in pull mode");
    GST_OBJECT_UNLOCK (src->srcpad);
    result = FALSE;
    goto done;
  }
}

static gboolean
gst_base_src_default_event (GstBaseSrc * src, GstEvent * event)
{
  gboolean result;

  switch (GST_EVENT_TYPE (event)) {
    case GST_EVENT_SEEK:
      /* is normally called when in push mode */
      if (!src->seekable)
        goto not_seekable;

      result = gst_base_src_perform_seek (src, event, TRUE);
      break;
    case GST_EVENT_FLUSH_START:
      /* cancel any blocking getrange, is normally called
       * when in pull mode. */
      result = gst_base_src_set_flushing (src, TRUE, FALSE, TRUE, NULL);
      break;
    case GST_EVENT_FLUSH_STOP:
      result = gst_base_src_set_flushing (src, FALSE, TRUE, TRUE, NULL);
      break;
    default:
      result = TRUE;
      break;
  }
  return result;

  /* ERRORS */
not_seekable:
  {
    GST_DEBUG_OBJECT (src, "is not seekable");
    return FALSE;
  }
}

static gboolean
gst_base_src_event_handler (GstPad * pad, GstEvent * event)
{
  GstBaseSrc *src;
  GstBaseSrcClass *bclass;
  gboolean result = FALSE;

  src = GST_BASE_SRC (gst_pad_get_parent (pad));
  bclass = GST_BASE_SRC_GET_CLASS (src);

  if (bclass->event) {
    if (!(result = bclass->event (src, event)))
      goto subclass_failed;
  }

done:
  gst_event_unref (event);
  gst_object_unref (src);

  return result;

  /* ERRORS */
subclass_failed:
  {
    GST_DEBUG_OBJECT (src, "subclass refused event");
    goto done;
  }
}

static void
gst_base_src_set_property (GObject * object, guint prop_id,
    const GValue * value, GParamSpec * pspec)
{
  GstBaseSrc *src;

  src = GST_BASE_SRC (object);

  switch (prop_id) {
    case PROP_BLOCKSIZE:
      src->blocksize = g_value_get_ulong (value);
      break;
    case PROP_NUM_BUFFERS:
      src->num_buffers = g_value_get_int (value);
      break;
    case PROP_TYPEFIND:
      src->data.ABI.typefind = g_value_get_boolean (value);
      break;
    case PROP_DO_TIMESTAMP:
      src->priv->do_timestamp = g_value_get_boolean (value);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static void
gst_base_src_get_property (GObject * object, guint prop_id, GValue * value,
    GParamSpec * pspec)
{
  GstBaseSrc *src;

  src = GST_BASE_SRC (object);

  switch (prop_id) {
    case PROP_BLOCKSIZE:
      g_value_set_ulong (value, src->blocksize);
      break;
    case PROP_NUM_BUFFERS:
      g_value_set_int (value, src->num_buffers);
      break;
    case PROP_TYPEFIND:
      g_value_set_boolean (value, src->data.ABI.typefind);
      break;
    case PROP_DO_TIMESTAMP:
      g_value_set_boolean (value, src->priv->do_timestamp);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

/* with STREAM_LOCK and LOCK */
static GstClockReturn
gst_base_src_wait (GstBaseSrc * basesrc, GstClock * clock, GstClockTime time)
{
  GstClockReturn ret;
  GstClockID id;

  id = gst_clock_new_single_shot_id (clock, time);

  basesrc->clock_id = id;
  /* release the live lock while waiting */
  GST_LIVE_UNLOCK (basesrc);

  ret = gst_clock_id_wait (id, NULL);

  GST_LIVE_LOCK (basesrc);
  gst_clock_id_unref (id);
  basesrc->clock_id = NULL;

  return ret;
}

/* perform synchronisation on a buffer. 
 * with STREAM_LOCK.
 */
static GstClockReturn
gst_base_src_do_sync (GstBaseSrc * basesrc, GstBuffer * buffer)
{
  GstClockReturn result;
  GstClockTime start, end;
  GstBaseSrcClass *bclass;
  GstClockTime base_time;
  GstClock *clock;
  GstClockTime now = GST_CLOCK_TIME_NONE, timestamp;
  gboolean do_timestamp, first, pseudo_live;

  bclass = GST_BASE_SRC_GET_CLASS (basesrc);

  start = end = -1;
  if (bclass->get_times)
    bclass->get_times (basesrc, buffer, &start, &end);

  /* get buffer timestamp */
  timestamp = GST_BUFFER_TIMESTAMP (buffer);

  /* grab the lock to prepare for clocking and calculate the startup 
   * latency. */
  GST_OBJECT_LOCK (basesrc);

  /* if we are asked to sync against the clock we are a pseudo live element */
  pseudo_live = (start != -1 && basesrc->is_live);
  /* check for the first buffer */
  first = (basesrc->priv->latency == -1);

  if (timestamp != -1 && pseudo_live) {
    GstClockTime latency;

    /* we have a timestamp and a sync time, latency is the diff */
    if (timestamp <= start)
      latency = start - timestamp;
    else
      latency = 0;

    if (first) {
      GST_DEBUG_OBJECT (basesrc, "pseudo_live with latency %" GST_TIME_FORMAT,
          GST_TIME_ARGS (latency));
      /* first time we calculate latency, just configure */
      basesrc->priv->latency = latency;
    } else {
      if (basesrc->priv->latency != latency) {
        /* we have a new latency, FIXME post latency message */
        basesrc->priv->latency = latency;
        GST_DEBUG_OBJECT (basesrc, "latency changed to %" GST_TIME_FORMAT,
            GST_TIME_ARGS (latency));
      }
    }
  } else if (first) {
    GST_DEBUG_OBJECT (basesrc, "no latency needed, live %d, sync %d",
        basesrc->is_live, start != -1);
    basesrc->priv->latency = 0;
  }

  /* get clock, if no clock, we can't sync or do timestamps */
  if ((clock = GST_ELEMENT_CLOCK (basesrc)) == NULL)
    goto no_clock;

  base_time = GST_ELEMENT_CAST (basesrc)->base_time;

  do_timestamp = basesrc->priv->do_timestamp;

  /* first buffer, calculate the timestamp offset */
  if (first) {
    GstClockTime running_time;

    now = gst_clock_get_time (clock);
    running_time = now - base_time;

    GST_LOG_OBJECT (basesrc,
        "startup timestamp: %" GST_TIME_FORMAT ", running_time %"
        GST_TIME_FORMAT, GST_TIME_ARGS (timestamp),
        GST_TIME_ARGS (running_time));

    if (pseudo_live && timestamp != -1) {
      /* live source and we need to sync, add startup latency to all timestamps
       * to get the real running_time. Live sources should always timestamp
       * according to the current running time. */
      basesrc->priv->ts_offset = GST_CLOCK_DIFF (timestamp, running_time);

      GST_LOG_OBJECT (basesrc, "live with sync, ts_offset %" GST_TIME_FORMAT,
          GST_TIME_ARGS (basesrc->priv->ts_offset));
    } else {
      basesrc->priv->ts_offset = 0;
      GST_LOG_OBJECT (basesrc, "no timestamp offset needed");
    }

    if (!GST_CLOCK_TIME_IS_VALID (timestamp)) {
      if (do_timestamp)
        timestamp = running_time;
      else
        timestamp = 0;

      GST_BUFFER_TIMESTAMP (buffer) = timestamp;

      GST_LOG_OBJECT (basesrc, "created timestamp: %" GST_TIME_FORMAT,
          GST_TIME_ARGS (timestamp));
    }

    /* add the timestamp offset we need for sync */
    timestamp += basesrc->priv->ts_offset;
  } else {
    /* not the first buffer, the timestamp is the diff between the clock and
     * base_time */
    if (do_timestamp && !GST_CLOCK_TIME_IS_VALID (timestamp)) {
      now = gst_clock_get_time (clock);

      GST_BUFFER_TIMESTAMP (buffer) = now - base_time;

      GST_LOG_OBJECT (basesrc, "created timestamp: %" GST_TIME_FORMAT,
          GST_TIME_ARGS (now - base_time));
    }
  }

  /* if we don't have a buffer timestamp, we don't sync */
  if (!GST_CLOCK_TIME_IS_VALID (start))
    goto no_sync;

  if (basesrc->is_live && GST_CLOCK_TIME_IS_VALID (timestamp)) {
    /* for pseudo live sources, add our ts_offset to the timestamp */
    GST_BUFFER_TIMESTAMP (buffer) += basesrc->priv->ts_offset;
    start += basesrc->priv->ts_offset;
  }

  GST_LOG_OBJECT (basesrc,
      "waiting for clock, base time %" GST_TIME_FORMAT
      ", stream_start %" GST_TIME_FORMAT,
      GST_TIME_ARGS (base_time), GST_TIME_ARGS (start));
  GST_OBJECT_UNLOCK (basesrc);

  result = gst_base_src_wait (basesrc, clock, start + base_time);

  GST_LOG_OBJECT (basesrc, "clock entry done: %d", result);

  return result;

  /* special cases */
no_clock:
  {
    GST_DEBUG_OBJECT (basesrc, "we have no clock");
    GST_OBJECT_UNLOCK (basesrc);
    return GST_CLOCK_OK;
  }
no_sync:
  {
    GST_DEBUG_OBJECT (basesrc, "no sync needed");
    GST_OBJECT_UNLOCK (basesrc);
    return GST_CLOCK_OK;
  }
}

static gboolean
gst_base_src_update_length (GstBaseSrc * src, guint64 offset, guint * length)
{
  guint64 size, maxsize;
  GstBaseSrcClass *bclass;

  bclass = GST_BASE_SRC_GET_CLASS (src);

  /* only operate if we are working with bytes */
  if (src->segment.format != GST_FORMAT_BYTES)
    return TRUE;

  /* get total file size */
  size = (guint64) src->segment.duration;

  /* the max amount of bytes to read is the total size or
   * up to the segment.stop if present. */
  if (src->segment.stop != -1)
    maxsize = MIN (size, src->segment.stop);
  else
    maxsize = size;

  GST_DEBUG_OBJECT (src,
      "reading offset %" G_GUINT64_FORMAT ", length %u, size %" G_GINT64_FORMAT
      ", segment.stop %" G_GINT64_FORMAT ", maxsize %" G_GINT64_FORMAT, offset,
      *length, size, src->segment.stop, maxsize);

  /* check size if we have one */
  if (maxsize != -1) {
    /* if we run past the end, check if the file became bigger and 
     * retry. */
    if (G_UNLIKELY (offset + *length >= maxsize)) {
      /* see if length of the file changed */
      if (bclass->get_size)
        if (!bclass->get_size (src, &size))
          size = -1;