gstcontroller.c

GStreamer是一个开源的多媒体框架库。利用它

    g_list_free (prop->values);
    prop->last_requested_value = NULL;
    prop->values = NULL;
    res = TRUE;
  }
  g_mutex_unlock (self->lock);

  return (res);
}

/**
 * gst_controller_get:
 * @self: the controller object which handles the properties
 * @property_name: the name of the property to get
 * @timestamp: the time the control-change should be read from
 *
 * Gets the value for the given controller-handled property at the requested
 * time.
 *
 * Returns: the GValue of the property at the given time, or %NULL if the property isn't handled by the controller
 */
GValue *
gst_controller_get (GstController * self, gchar * property_name,
    GstClockTime timestamp)
{
  GstControlledProperty *prop;
  GValue *val = NULL;

  g_return_val_if_fail (GST_IS_CONTROLLER (self), NULL);
  g_return_val_if_fail (property_name, NULL);
  g_return_val_if_fail (GST_CLOCK_TIME_IS_VALID (timestamp), NULL);

  g_mutex_lock (self->lock);
  if ((prop = gst_controller_find_controlled_property (self, property_name))) {
    /* get current value via interpolator */
    val = prop->get (prop, timestamp);
  }
  g_mutex_unlock (self->lock);

  return (val);
}

/**
 * gst_controller_get_all:
 * @self: the controller to get the list from
 * @property_name: the name of the property to get the list for
 *
 * Returns a read-only copy of the list of GstTimedValue for the given property.
 * Free the list after done with it.
 *
 * Returns: a copy of the list, or %NULL if the property isn't handled by the controller
 */
const GList *
gst_controller_get_all (GstController * self, gchar * property_name)
{
  GList *res = NULL;
  GstControlledProperty *prop;

  g_return_val_if_fail (GST_IS_CONTROLLER (self), NULL);
  g_return_val_if_fail (property_name, NULL);

  g_mutex_lock (self->lock);
  if ((prop = gst_controller_find_controlled_property (self, property_name))) {
    res = g_list_copy (prop->values);
  }
  g_mutex_unlock (self->lock);

  return (res);
}

/**
 * gst_controller_suggest_next_sync:
 * @self: the controller that handles the values
 *
 * Returns a suggestion for timestamps where buffers should be split
 * to get best controller results.
 *
 * Returns: Returns the suggested timestamp or %GST_CLOCK_TIME_NONE
 * if no control-rate was set.
 *
 * Since: 0.10.13
 */
GstClockTime
gst_controller_suggest_next_sync (GstController * self)
{
  GstClockTime ret;

  g_return_val_if_fail (GST_IS_CONTROLLER (self), GST_CLOCK_TIME_NONE);
  g_return_val_if_fail (self->priv->control_rate != GST_CLOCK_TIME_NONE,
      GST_CLOCK_TIME_NONE);

  g_mutex_lock (self->lock);

  /* TODO: Implement more logic, depending on interpolation mode
   * and control points */
  ret = self->priv->last_sync + self->priv->control_rate;

  g_mutex_unlock (self->lock);

  return ret;
}

/**
 * gst_controller_sync_values:
 * @self: the controller that handles the values
 * @timestamp: the time that should be processed
 *
 * Sets the properties of the element, according to the controller that (maybe)
 * handles them and for the given timestamp.
 *
 * Returns: %TRUE if the controller values could be applied to the object
 * properties, %FALSE otherwise
 */
gboolean
gst_controller_sync_values (GstController * self, GstClockTime timestamp)
{
  GstControlledProperty *prop;
  GList *node;
  GValue *value;
  gboolean live = FALSE;

  g_return_val_if_fail (GST_IS_CONTROLLER (self), FALSE);
  g_return_val_if_fail (GST_CLOCK_TIME_IS_VALID (timestamp), FALSE);

  GST_LOG ("sync_values");

  g_mutex_lock (self->lock);
  /* go over the controlled properties of the controller */
  for (node = self->properties; node; node = g_list_next (node)) {
    prop = node->data;
    GST_DEBUG ("  property '%s' at ts=%" G_GUINT64_FORMAT, prop->name,
        timestamp);

    live = FALSE;
    if (G_UNLIKELY (G_IS_VALUE (&prop->live_value.value))) {
      GList *lnode =
          gst_controlled_property_find_control_point_node (prop, timestamp);
      if (G_UNLIKELY (!lnode)) {
        GST_DEBUG ("    no control changes in the queue");
        live = TRUE;
      } else {
        GstControlPoint *cp = lnode->data;

        if (prop->live_value.timestamp < cp->timestamp) {
          g_value_unset (&prop->live_value.value);
          GST_DEBUG ("    live value resetted");
        } else if (prop->live_value.timestamp < timestamp) {
          live = TRUE;
        }
      }
    }
    if (G_LIKELY (!live)) {
      /* get current value via interpolator */
      value = prop->get (prop, timestamp);
      prop->last_value.timestamp = timestamp;
      g_value_copy (value, &prop->last_value.value);
      g_object_set_property (self->object, prop->name, value);
    }
  }
  if (G_LIKELY (!live))
    self->priv->last_sync = timestamp;

  g_mutex_unlock (self->lock);
  /* TODO what can here go wrong, to return FALSE ?
     BilboEd : Nothing I guess, as long as all the checks are made when creating the controller,
     adding/removing controlled properties, etc...
   */

  return (TRUE);
}

/**
 * gst_controller_get_value_arrays:
 * @self: the controller that handles the values
 * @timestamp: the time that should be processed
 * @value_arrays: list to return the control-values in
 *
 * Function to be able to get an array of values for one or more given element
 * properties.
 *
 * All fields of the %GstValueArray in the list must be filled correctly.
 * Especially the GstValueArray->values arrays must be big enough to keep
 * the requested amount of values.
 *
 * The types of the values in the array are the same as the property's type.
 *
 * Returns: %TRUE if the given array(s) could be filled, %FALSE otherwise
 */
gboolean
gst_controller_get_value_arrays (GstController * self,
    GstClockTime timestamp, GSList * value_arrays)
{
  gboolean res = TRUE;
  GSList *node;

  g_return_val_if_fail (GST_IS_CONTROLLER (self), FALSE);
  g_return_val_if_fail (GST_CLOCK_TIME_IS_VALID (timestamp), FALSE);
  g_return_val_if_fail (value_arrays, FALSE);

  for (node = value_arrays; (res && node); node = g_slist_next (node)) {
    res = gst_controller_get_value_array (self, timestamp, node->data);
  }

  return (res);
}

/**
 * gst_controller_get_value_array:
 * @self: the controller that handles the values
 * @timestamp: the time that should be processed
 * @value_array: array to put control-values in
 *
 * Function to be able to get an array of values for one element property.
 *
 * All fields of @value_array must be filled correctly. Especially the
 * @value_array->values array must be big enough to keep the requested amount
 * of values.
 *
 * The type of the values in the array is the same as the property's type.
 *
 * Returns: %TRUE if the given array could be filled, %FALSE otherwise
 */
gboolean
gst_controller_get_value_array (GstController * self, GstClockTime timestamp,
    GstValueArray * value_array)
{
  gboolean res = FALSE;
  GstControlledProperty *prop;

  g_return_val_if_fail (GST_IS_CONTROLLER (self), FALSE);
  g_return_val_if_fail (GST_CLOCK_TIME_IS_VALID (timestamp), FALSE);
  g_return_val_if_fail (value_array, FALSE);
  g_return_val_if_fail (value_array->property_name, FALSE);
  g_return_val_if_fail (value_array->values, FALSE);

  g_mutex_lock (self->lock);

  if ((prop =
          gst_controller_find_controlled_property (self,
              value_array->property_name))) {
    /* get current value_array via interpolator */
    res = prop->get_value_array (prop, timestamp, value_array);
  }

  g_mutex_unlock (self->lock);
  return (res);
}

/**
 * gst_controller_set_interpolation_mode:
 * @self: the controller object
 * @property_name: the name of the property for which to change the interpolation
 * @mode: interpolation mode
 *
 * Sets the given interpolation mode on the given property.
 *
 * <note><para>Quadratic, cubic and user interpolation is not yet available.
 * </para></note>
 *
 * Returns: %TRUE if the property is handled by the controller, %FALSE otherwise
 */
gboolean
gst_controller_set_interpolation_mode (GstController * self,
    gchar * property_name, GstInterpolateMode mode)
{
  gboolean res = FALSE;
  GstControlledProperty *prop;

  g_return_val_if_fail (GST_IS_CONTROLLER (self), FALSE);
  g_return_val_if_fail (property_name, FALSE);

  g_mutex_lock (self->lock);
  if ((prop = gst_controller_find_controlled_property (self, property_name))) {
    /* TODO shouldn't this also get a GstInterpolateMethod *user_method
       for the case mode==GST_INTERPOLATE_USER
     */
    res = gst_controlled_property_set_interpolation_mode (prop, mode);
  }
  g_mutex_unlock (self->lock);

  return (res);
}

/* gobject handling */

static void
_gst_controller_get_property (GObject * object, guint property_id,
    GValue * value, GParamSpec * pspec)
{
  GstController *self = GST_CONTROLLER (object);

  switch (property_id) {
    case PROP_CONTROL_RATE:{
      /* FIXME: don't change if element is playing, controller works for GObject
         so this wont work

         GstState c_state, p_state;
         GstStateChangeReturn ret;

         ret = gst_element_get_state (self->object, &c_state, &p_state, 0);
         if ((ret == GST_STATE_CHANGE_SUCCESS &&
         (c_state == GST_STATE_NULL || c_state == GST_STATE_READY)) ||
         (ret == GST_STATE_CHANGE_ASYNC &&
         (p_state == GST_STATE_NULL || p_state == GST_STATE_READY))) {
       */
      g_value_set_uint64 (value, self->priv->control_rate);
      /*
         }
         else {
         GST_WARNING ("Changing the control rate is only allowed if the elemnt"
         " is in NULL or READY");
         }
       */
    }
      break;
    default:{
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
    }
      break;
  }
}

/* sets the given properties for this object */
static void
_gst_controller_set_property (GObject * object, guint property_id,
    const GValue * value, GParamSpec * pspec)
{
  GstController *self = GST_CONTROLLER (object);

  switch (property_id) {
    case PROP_CONTROL_RATE:{
      self->priv->control_rate = g_value_get_uint64 (value);
    }
      break;
    default:{
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
    }
      break;
  }
}

static void
_gst_controller_dispose (GObject * object)
{
  GstController *self = GST_CONTROLLER (object);

  if (self->object != NULL) {
    g_mutex_lock (self->lock);
    /* free list of properties */
    if (self->properties) {
      GList *node;

      for (node = self->properties; node; node = g_list_next (node)) {
        GstControlledProperty *prop = node->data;

        g_signal_handler_disconnect (self->object, prop->notify_handler_id);
        gst_controlled_property_free (prop);
      }
      g_list_free (self->properties);
      self->properties = NULL;
    }

    /* remove controller from object's qdata list */
    g_object_set_qdata (self->object, __gst_controller_key, NULL);
    g_object_unref (self->object);
    self->object = NULL;
    g_mutex_unlock (self->lock);
  }

  if (G_OBJECT_CLASS (parent_class)->dispose)
    (G_OBJECT_CLASS (parent_class)->dispose) (object);
}

static void
_gst_controller_finalize (GObject * object)
{
  GstController *self = GST_CONTROLLER (object);

  g_mutex_free (self->lock);

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

static void
_gst_controller_init (GTypeInstance * instance, gpointer g_class)
{
  GstController *self = GST_CONTROLLER (instance);

  self->lock = g_mutex_new ();
  self->priv =
      G_TYPE_INSTANCE_GET_PRIVATE (self, GST_TYPE_CONTROLLER,
      GstControllerPrivate);
  self->priv->last_sync = GST_CLOCK_TIME_NONE;
  self->priv->control_rate = 100 * GST_MSECOND;
}

static void
_gst_controller_class_init (GstControllerClass * klass)
{
  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);

  parent_class = g_type_class_peek_parent (klass);
  g_type_class_add_private (klass, sizeof (GstControllerPrivate));

  gobject_class->set_property = _gst_controller_set_property;
  gobject_class->get_property = _gst_controller_get_property;
  gobject_class->dispose = _gst_controller_dispose;
  gobject_class->finalize = _gst_controller_finalize;

  __gst_controller_key = g_quark_from_string ("gst::controller");

  /* register properties */
  g_object_class_install_property (gobject_class, PROP_CONTROL_RATE,
      g_param_spec_uint64 ("control-rate",
          "control rate",
          "Controlled properties will be updated at least every control-rate nanoseconds",
          1, G_MAXUINT, 100 * GST_MSECOND, G_PARAM_READWRITE));

  /* register signals */
  /* set defaults for overridable methods */
}

GType
gst_controller_get_type (void)
{
  static GType type = 0;

  if (type == 0) {
    static const GTypeInfo info = {
      sizeof (GstControllerClass),
      NULL,                     /* base_init */
      NULL,                     /* base_finalize */
      (GClassInitFunc) _gst_controller_class_init,      /* class_init */
      NULL,                     /* class_finalize */
      NULL,                     /* class_data */
      sizeof (GstController),
      0,                        /* n_preallocs */
      (GInstanceInitFunc) _gst_controller_init, /* instance_init */
      NULL                      /* value_table */
    };
    type = g_type_register_static (G_TYPE_OBJECT, "GstController", &info, 0);
  }
  return type;
}