gstbasesink.c

GStreamer是一个开源的多媒体框架库。利用它

}

static GstFlowReturn
gst_base_sink_pad_buffer_alloc (GstPad * pad, guint64 offset, guint size,
    GstCaps * caps, GstBuffer ** buf)
{
  GstBaseSinkClass *bclass;
  GstBaseSink *bsink;
  GstFlowReturn result = GST_FLOW_OK;

  bsink = GST_BASE_SINK (gst_pad_get_parent (pad));
  bclass = GST_BASE_SINK_GET_CLASS (bsink);

  if (bclass->buffer_alloc)
    result = bclass->buffer_alloc (bsink, offset, size, caps, buf);
  else
    *buf = NULL;                /* fallback in gstpad.c will allocate generic buffer */

  gst_object_unref (bsink);

  return result;
}

static void
gst_base_sink_init (GstBaseSink * basesink, gpointer g_class)
{
  GstPadTemplate *pad_template;
  GstBaseSinkPrivate *priv;

  basesink->priv = priv = GST_BASE_SINK_GET_PRIVATE (basesink);

  pad_template =
      gst_element_class_get_pad_template (GST_ELEMENT_CLASS (g_class), "sink");
  g_return_if_fail (pad_template != NULL);

  basesink->sinkpad = gst_pad_new_from_template (pad_template, "sink");

  gst_pad_set_getcaps_function (basesink->sinkpad,
      GST_DEBUG_FUNCPTR (gst_base_sink_pad_getcaps));
  gst_pad_set_setcaps_function (basesink->sinkpad,
      GST_DEBUG_FUNCPTR (gst_base_sink_pad_setcaps));
  gst_pad_set_fixatecaps_function (basesink->sinkpad,
      GST_DEBUG_FUNCPTR (gst_base_sink_pad_fixate));
  gst_pad_set_bufferalloc_function (basesink->sinkpad,
      GST_DEBUG_FUNCPTR (gst_base_sink_pad_buffer_alloc));
  gst_pad_set_activate_function (basesink->sinkpad,
      GST_DEBUG_FUNCPTR (gst_base_sink_pad_activate));
  gst_pad_set_activatepush_function (basesink->sinkpad,
      GST_DEBUG_FUNCPTR (gst_base_sink_pad_activate_push));
  gst_pad_set_activatepull_function (basesink->sinkpad,
      GST_DEBUG_FUNCPTR (gst_base_sink_pad_activate_pull));
  gst_pad_set_event_function (basesink->sinkpad,
      GST_DEBUG_FUNCPTR (gst_base_sink_event));
  gst_pad_set_chain_function (basesink->sinkpad,
      GST_DEBUG_FUNCPTR (gst_base_sink_chain));
  gst_element_add_pad (GST_ELEMENT_CAST (basesink), basesink->sinkpad);

  basesink->pad_mode = GST_ACTIVATE_NONE;
  basesink->preroll_queue = g_queue_new ();
  basesink->abidata.ABI.clip_segment = gst_segment_new ();

  basesink->can_activate_push = DEFAULT_CAN_ACTIVATE_PUSH;
  basesink->can_activate_pull = DEFAULT_CAN_ACTIVATE_PULL;

  basesink->sync = DEFAULT_SYNC;
  basesink->abidata.ABI.max_lateness = DEFAULT_MAX_LATENESS;
  gst_atomic_int_set (&priv->qos_enabled, DEFAULT_QOS);

  GST_OBJECT_FLAG_SET (basesink, GST_ELEMENT_IS_SINK);
}

static void
gst_base_sink_finalize (GObject * object)
{
  GstBaseSink *basesink;

  basesink = GST_BASE_SINK (object);

  g_queue_free (basesink->preroll_queue);
  gst_segment_free (basesink->abidata.ABI.clip_segment);

  G_OBJECT_CLASS (parent_class)->finalize (object);
}

/**
 * gst_base_sink_set_sync:
 * @sink: the sink
 * @sync: the new sync value.
 *
 * Configures @sink to synchronize on the clock or not. When
 * @sync is FALSE, incomming samples will be played as fast as
 * possible. If @sync is TRUE, the timestamps of the incomming
 * buffers will be used to schedule the exact render time of its
 * contents.
 *
 * Since: 0.10.4
 */
void
gst_base_sink_set_sync (GstBaseSink * sink, gboolean sync)
{
  GST_OBJECT_LOCK (sink);
  sink->sync = sync;
  GST_OBJECT_UNLOCK (sink);
}

/**
 * gst_base_sink_get_sync:
 * @sink: the sink
 *
 * Checks if @sink is currently configured to synchronize against the
 * clock.
 *
 * Returns: TRUE if the sink is configured to synchronize against the clock.
 *
 * Since: 0.10.4
 */
gboolean
gst_base_sink_get_sync (GstBaseSink * sink)
{
  gboolean res;

  GST_OBJECT_LOCK (sink);
  res = sink->sync;
  GST_OBJECT_UNLOCK (sink);

  return res;
}

/**
 * gst_base_sink_set_max_lateness:
 * @sink: the sink
 * @max_lateness: the new max lateness value.
 *
 * Sets the new max lateness value to @max_lateness. This value is
 * used to decide if a buffer should be dropped or not based on the
 * buffer timestamp and the current clock time. A value of -1 means
 * an unlimited time.
 *
 * Since: 0.10.4
 */
void
gst_base_sink_set_max_lateness (GstBaseSink * sink, gint64 max_lateness)
{
  GST_OBJECT_LOCK (sink);
  sink->abidata.ABI.max_lateness = max_lateness;
  GST_OBJECT_UNLOCK (sink);
}

/**
 * gst_base_sink_get_max_lateness:
 * @sink: the sink
 *
 * Gets the max lateness value. See gst_base_sink_set_max_lateness for
 * more details.
 *
 * Returns: The maximum time in nanoseconds that a buffer can be late
 * before it is dropped and not rendered. A value of -1 means an
 * unlimited time.
 *
 * Since: 0.10.4
 */
gint64
gst_base_sink_get_max_lateness (GstBaseSink * sink)
{
  gint64 res;

  GST_OBJECT_LOCK (sink);
  res = sink->abidata.ABI.max_lateness;
  GST_OBJECT_UNLOCK (sink);

  return res;
}

/**
 * gst_base_sink_set_qos_enabled:
 * @sink: the sink
 * @enabled: the new qos value.
 *
 * Configures @sink to send Quality-of-Service events upstream.
 *
 * Since: 0.10.5
 */
void
gst_base_sink_set_qos_enabled (GstBaseSink * sink, gboolean enabled)
{
  gst_atomic_int_set (&sink->priv->qos_enabled, enabled);
}

/**
 * gst_base_sink_is_qos_enabled:
 * @sink: the sink
 *
 * Checks if @sink is currently configured to send Quality-of-Service events
 * upstream.
 *
 * Returns: TRUE if the sink is configured to perform Quality-of-Service.
 *
 * Since: 0.10.5
 */
gboolean
gst_base_sink_is_qos_enabled (GstBaseSink * sink)
{
  gboolean res;

  res = g_atomic_int_get (&sink->priv->qos_enabled);

  return res;
}

/**
 * gst_base_sink_get_latency:
 * @sink: the sink
 *
 * Get the currently configured latency.
 *
 * Returns: The configured latency.
 *
 * Since: 0.10.12
 */
GstClockTime
gst_base_sink_get_latency (GstBaseSink * sink)
{
  GstClockTime res;

  GST_OBJECT_LOCK (sink);
  res = sink->priv->latency;
  GST_OBJECT_UNLOCK (sink);

  return res;
}

/**
 * gst_base_sink_query_latency:
 * @sink: the sink
 * @live: if the sink is live
 * @upstream_live: if an upstream element is live
 * @min_latency: the min latency of the upstream elements
 * @max_latency: the max latency of the upstream elements
 *
 * Query the sink for the latency parameters. The latency will be queried from
 * the upstream elements. @live will be TRUE if @sink is configured to
 * synchronize against the clock. @upstream_live will be TRUE if an upstream
 * element is live. 
 *
 * If both @live and @upstream_live are TRUE, the sink will want to compensate
 * for the latency introduced by the upstream elements by setting the
 * @min_latency to a strictly possitive value.
 *
 * This function is mostly used by subclasses. 
 *
 * Returns: TRUE if the query succeeded.
 *
 * Since: 0.10.12
 */
gboolean
gst_base_sink_query_latency (GstBaseSink * sink, gboolean * live,
    gboolean * upstream_live, GstClockTime * min_latency,
    GstClockTime * max_latency)
{
  gboolean l, us_live, res;
  GstClockTime min, max;
  GstQuery *query;
  GstClockTime us_min, us_max;

  /* we are live when we sync to the clock */
  l = gst_base_sink_get_sync (sink);

  /* assume no latency */
  min = 0;
  max = -1;
  us_live = FALSE;

  query = gst_query_new_latency ();

  /* ask the peer for the latency */
  if (!(res = gst_base_sink_peer_query (sink, query)))
    goto query_failed;

  /* get upstream min and max latency */
  gst_query_parse_latency (query, &us_live, &us_min, &us_max);
  if (us_live) {
    /* upstream live, use its latency, subclasses should use these
     * values to create the complete latency. */
    min = us_min;
    max = us_max;
  }

  GST_DEBUG_OBJECT (sink, "latency query: live: %d, upstream: %d, min %"
      GST_TIME_FORMAT ", max %" GST_TIME_FORMAT, l, us_live,
      GST_TIME_ARGS (min), GST_TIME_ARGS (max));

  if (live)
    *live = l;
  if (upstream_live)
    *upstream_live = us_live;
  if (min_latency)
    *min_latency = min;
  if (max_latency)
    *max_latency = max;

done:
  gst_query_unref (query);

  return res;

  /* ERRORS */
query_failed:
  {
    GST_DEBUG_OBJECT (sink, "latency query failed");
    goto done;
  }
}

static void
gst_base_sink_set_property (GObject * object, guint prop_id,
    const GValue * value, GParamSpec * pspec)
{
  GstBaseSink *sink = GST_BASE_SINK (object);

  switch (prop_id) {
    case PROP_PREROLL_QUEUE_LEN:
      /* preroll lock necessary to serialize with finish_preroll */
      GST_PAD_PREROLL_LOCK (sink->sinkpad);
      sink->preroll_queue_max_len = g_value_get_uint (value);
      GST_PAD_PREROLL_UNLOCK (sink->sinkpad);
      break;
    case PROP_SYNC:
      gst_base_sink_set_sync (sink, g_value_get_boolean (value));
      break;
    case PROP_MAX_LATENESS:
      gst_base_sink_set_max_lateness (sink, g_value_get_int64 (value));
      break;
    case PROP_QOS:
      gst_base_sink_set_qos_enabled (sink, g_value_get_boolean (value));
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static void
gst_base_sink_get_property (GObject * object, guint prop_id, GValue * value,
    GParamSpec * pspec)
{
  GstBaseSink *sink = GST_BASE_SINK (object);

  switch (prop_id) {
    case PROP_PREROLL_QUEUE_LEN:
      GST_PAD_PREROLL_LOCK (sink->sinkpad);
      g_value_set_uint (value, sink->preroll_queue_max_len);
      GST_PAD_PREROLL_UNLOCK (sink->sinkpad);
      break;
    case PROP_SYNC:
      g_value_set_boolean (value, gst_base_sink_get_sync (sink));
      break;
    case PROP_MAX_LATENESS:
      g_value_set_int64 (value, gst_base_sink_get_max_lateness (sink));
      break;
    case PROP_QOS:
      g_value_set_boolean (value, gst_base_sink_is_qos_enabled (sink));
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}


static GstCaps *
gst_base_sink_get_caps (GstBaseSink * sink)
{
  return NULL;
}

static gboolean
gst_base_sink_set_caps (GstBaseSink * sink, GstCaps * caps)
{
  return TRUE;
}

static GstFlowReturn
gst_base_sink_buffer_alloc (GstBaseSink * sink, guint64 offset, guint size,
    GstCaps * caps, GstBuffer ** buf)
{
  *buf = NULL;
  return GST_FLOW_OK;
}

/* with PREROLL_LOCK, STREAM_LOCK */
static void
gst_base_sink_preroll_queue_flush (GstBaseSink * basesink, GstPad * pad)
{
  GstMiniObject *obj;

  GST_DEBUG_OBJECT (basesink, "flushing queue %p", basesink);
  while ((obj = g_queue_pop_head (basesink->preroll_queue))) {
    GST_DEBUG_OBJECT (basesink, "popped %p", obj);
    gst_mini_object_unref (obj);
  }
  /* we can't have EOS anymore now */
  basesink->eos = FALSE;
  basesink->eos_queued = FALSE;
  basesink->preroll_queued = 0;
  basesink->buffers_queued = 0;
  basesink->events_queued = 0;
  basesink->have_preroll = FALSE;
  /* and signal any waiters now */
  GST_PAD_PREROLL_SIGNAL (pad);
}

/* with STREAM_LOCK, configures given segment with the event information. */
static void
gst_base_sink_configure_segment (GstBaseSink * basesink, GstPad * pad,
    GstEvent * event, GstSegment * segment)
{
  gboolean update;
  gdouble rate, arate;
  GstFormat format;
  gint64 start;
  gint64 stop;
  gint64 time;

  /* the newsegment event is needed to bring the buffer timestamps to the
   * stream time and to drop samples outside of the playback segment. */
  gst_event_parse_new_segment_full (event, &update, &rate, &arate, &format,
      &start, &stop, &time);

  /* The segment is protected with both the STREAM_LOCK and the OBJECT_LOCK.
   * We protect with the OBJECT_LOCK so that we can use the values to
   * safely answer a POSITION query. */
  GST_OBJECT_LOCK (basesink);
  gst_segment_set_newsegment_full (segment, update, rate, arate, format, start,
      stop, time);