pipewire/pinos/client/stream.c

/* Pinos
 * Copyright (C) 2015 Wim Taymans <wim.taymans@gmail.com>
 *
 * 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.
 */

#include <sys/socket.h>
#include <string.h>

#include <gio/gunixfdlist.h>
#include <gio/gunixfdmessage.h>

#include "pinos/server/daemon.h"
#include "pinos/client/pinos.h"
#include "pinos/client/context.h"
#include "pinos/client/stream.h"
#include "pinos/client/enumtypes.h"

#include "pinos/client/private.h"

struct _PinosStreamPrivate
{
  PinosContext *context;
  gchar *name;
  PinosProperties *properties;

  guint id;

  PinosStreamState state;
  GError *error;

  PinosDirection direction;
  gchar *path;
  GBytes *possible_formats;
  gboolean provide;

  GBytes *format;

  PinosNode *node;
  PinosPort *port;
  gboolean disconnecting;

  PinosStreamMode mode;
};

#define PINOS_STREAM_GET_PRIVATE(obj)  \
   (G_TYPE_INSTANCE_GET_PRIVATE ((obj), PINOS_TYPE_STREAM, PinosStreamPrivate))

G_DEFINE_TYPE (PinosStream, pinos_stream, G_TYPE_OBJECT);

enum
{
  PROP_0,
  PROP_CONTEXT,
  PROP_NAME,
  PROP_PROPERTIES,
  PROP_STATE,
  PROP_POSSIBLE_FORMATS,
  PROP_FORMAT,
};

enum
{
  SIGNAL_NEW_BUFFER,
  LAST_SIGNAL
};

static guint signals[LAST_SIGNAL] = { 0 };

static void
pinos_stream_get_property (GObject    *_object,
                           guint       prop_id,
                           GValue     *value,
                           GParamSpec *pspec)
{
  PinosStream *stream = PINOS_STREAM (_object);
  PinosStreamPrivate *priv = stream->priv;

  switch (prop_id) {
    case PROP_CONTEXT:
      g_value_set_object (value, priv->context);
      break;

    case PROP_NAME:
      g_value_set_string (value, priv->name);
      break;

    case PROP_PROPERTIES:
      g_value_set_boxed (value, priv->properties);
      break;

    case PROP_STATE:
      g_value_set_enum (value, priv->state);
      break;

    case PROP_POSSIBLE_FORMATS:
      g_value_set_boxed (value, priv->possible_formats);
      break;

    case PROP_FORMAT:
      g_value_set_boxed (value, priv->format);
      break;

    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (stream, prop_id, pspec);
      break;
    }
}

static void
pinos_stream_set_property (GObject      *_object,
                           guint         prop_id,
                           const GValue *value,
                           GParamSpec   *pspec)
{
  PinosStream *stream = PINOS_STREAM (_object);
  PinosStreamPrivate *priv = stream->priv;

  switch (prop_id) {
    case PROP_CONTEXT:
      priv->context = g_value_dup_object (value);
      break;

    case PROP_NAME:
      priv->name = g_value_dup_string (value);
      break;

    case PROP_PROPERTIES:
      if (priv->properties)
        pinos_properties_free (priv->properties);
      priv->properties = g_value_dup_boxed (value);
      break;

    case PROP_FORMAT:
      if (priv->format)
        g_bytes_unref (priv->format);
      priv->format = g_value_dup_boxed (value);
      break;

    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (stream, prop_id, pspec);
      break;
    }
}

static gboolean
do_notify_state (PinosStream *stream)
{
  g_object_notify (G_OBJECT (stream), "state");
  g_object_unref (stream);
  return FALSE;
}

static void
stream_set_state (PinosStream      *stream,
                  PinosStreamState  state,
                  GError           *error)
{
  if (stream->priv->state != state) {
    if (error) {
      g_clear_error (&stream->priv->error);
      stream->priv->error = error;
    }
    stream->priv->state = state;
    g_main_context_invoke (stream->priv->context->priv->context,
                          (GSourceFunc) do_notify_state,
                          g_object_ref (stream));
  } else {
    if (error)
      g_error_free (error);
  }
}

static void
subscription_cb (PinosSubscribe         *subscribe,
                 PinosSubscriptionEvent  event,
                 PinosSubscriptionFlags  flags,
                 GDBusProxy             *object,
                 gpointer                user_data)
{
  PinosStream *stream = PINOS_STREAM (user_data);
  PinosStreamPrivate *priv = stream->priv;

  switch (flags) {
    case PINOS_SUBSCRIPTION_FLAG_NODE:
      if (event == PINOS_SUBSCRIPTION_EVENT_REMOVE) {
        if (object == priv->node && !priv->disconnecting) {
          stream_set_state (stream,
                            PINOS_STREAM_STATE_ERROR,
                            g_error_new_literal (G_IO_ERROR,
                                                 G_IO_ERROR_CLOSED,
                                                 "Node disappeared"));
        }
      }
      break;

    case PINOS_SUBSCRIPTION_FLAG_PORT:
      break;

    default:
      break;
  }
}

static void
pinos_stream_constructed (GObject * object)
{
  PinosStream *stream = PINOS_STREAM (object);
  PinosStreamPrivate *priv = stream->priv;

  priv->id = g_signal_connect (priv->context->priv->subscribe,
                    "subscription-event",
                    (GCallback) subscription_cb,
                    stream);

  G_OBJECT_CLASS (pinos_stream_parent_class)->constructed (object);
}

static void
pinos_stream_finalize (GObject * object)
{
  PinosStream *stream = PINOS_STREAM (object);
  PinosStreamPrivate *priv = stream->priv;

  g_debug ("free stream %p", stream);

  g_clear_object (&priv->node);

  if (priv->possible_formats)
    g_bytes_unref (priv->possible_formats);
  if (priv->format)
    g_bytes_unref (priv->format);

  g_free (priv->path);
  if (priv->possible_formats)
    g_bytes_unref (priv->possible_formats);

  g_clear_error (&priv->error);

  if (priv->properties)
    pinos_properties_free (priv->properties);
  g_signal_handler_disconnect (priv->context->priv->subscribe, priv->id);
  g_clear_object (&priv->context);
  g_free (priv->name);

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

static void
pinos_stream_class_init (PinosStreamClass * klass)
{
  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);

  g_type_class_add_private (klass, sizeof (PinosStreamPrivate));

  gobject_class->constructed = pinos_stream_constructed;
  gobject_class->finalize = pinos_stream_finalize;
  gobject_class->set_property = pinos_stream_set_property;
  gobject_class->get_property = pinos_stream_get_property;

  /**
   * PinosStream:context
   *
   * The context of the stream.
   */
  g_object_class_install_property (gobject_class,
                                   PROP_CONTEXT,
                                   g_param_spec_object ("context",
                                                        "Context",
                                                        "The context",
                                                        PINOS_TYPE_CONTEXT,
                                                        G_PARAM_READWRITE |
                                                        G_PARAM_CONSTRUCT_ONLY |
                                                        G_PARAM_STATIC_STRINGS));
  /**
   * PinosStream:name
   *
   * The name of the stream as specified at construction time.
   */
  g_object_class_install_property (gobject_class,
                                   PROP_NAME,
                                   g_param_spec_string ("name",
                                                        "Name",
                                                        "The name of the stream",
                                                        NULL,
                                                        G_PARAM_READWRITE |
                                                        G_PARAM_CONSTRUCT_ONLY |
                                                        G_PARAM_STATIC_STRINGS));
  /**
   * PinosStream:properties
   *
   * The properties of the stream as specified at construction time.
   */
  g_object_class_install_property (gobject_class,
                                   PROP_PROPERTIES,
                                   g_param_spec_boxed ("properties",
                                                       "Properties",
                                                       "The properties of the stream",
                                                       PINOS_TYPE_PROPERTIES,
                                                       G_PARAM_READWRITE |
                                                       G_PARAM_CONSTRUCT_ONLY |
                                                       G_PARAM_STATIC_STRINGS));
  /**
   * PinosStream:state
   *
   * The state of the stream. Use the notify::state signal to be notified
   * of state changes.
   */
  g_object_class_install_property (gobject_class,
                                   PROP_STATE,
                                   g_param_spec_enum ("state",
                                                      "State",
                                                      "The stream state",
                                                      PINOS_TYPE_STREAM_STATE,
                                                      PINOS_STREAM_STATE_UNCONNECTED,
                                                      G_PARAM_READABLE |
                                                      G_PARAM_STATIC_STRINGS));
  /**
   * PinosStream:possible-formats
   *
   * The possible formats for the stream. this can only be used after connecting
   * the stream for capture or provide.
   */
  g_object_class_install_property (gobject_class,
                                   PROP_POSSIBLE_FORMATS,
                                   g_param_spec_boxed ("possible-formats",
                                                       "Possible Formats",
                                                       "The possbile formats of the stream",
                                                       G_TYPE_BYTES,
                                                       G_PARAM_READABLE |
                                                       G_PARAM_STATIC_STRINGS));
  /**
   * PinosStream:formats
   *
   * The format of the stream. This will be set after starting the stream.
   */
  g_object_class_install_property (gobject_class,
                                   PROP_FORMAT,
                                   g_param_spec_boxed ("format",
                                                       "Format",
                                                       "The format of the stream",
                                                       G_TYPE_BYTES,
                                                       G_PARAM_READWRITE |
                                                       G_PARAM_STATIC_STRINGS));
  /**
   * PinosStream:new-buffer
   *
   * When doing pinos_stream_start() with #PINOS_STREAM_MODE_BUFFER, this signal
   * will be fired whenever a new buffer can be obtained with
   * pinos_stream_capture_buffer().
   */
  signals[SIGNAL_NEW_BUFFER] = g_signal_new ("new-buffer",
                                             G_TYPE_FROM_CLASS (klass),
                                             G_SIGNAL_RUN_LAST,
                                             0,
                                             NULL,
                                             NULL,
                                             g_cclosure_marshal_generic,
                                             G_TYPE_NONE,
                                             0,
                                             G_TYPE_NONE);
}

static void
pinos_stream_init (PinosStream * stream)
{
  PinosStreamPrivate *priv = stream->priv = PINOS_STREAM_GET_PRIVATE (stream);

  g_debug ("new stream %p", stream);

  priv->state = PINOS_STREAM_STATE_UNCONNECTED;
}

/**
 * pinos_stream_state_as_string:
 * @state: a #PinosStreamState
 *
 * Return the string representation of @state.
 *
 * Returns: the string representation of @state.
 */
const gchar *
pinos_stream_state_as_string (PinosStreamState state)
{
  GEnumValue *val;

  val = g_enum_get_value (G_ENUM_CLASS (g_type_class_ref (PINOS_TYPE_STREAM_STATE)),
                          state);

  return val == NULL ? "invalid-state" : val->value_nick;
}

/**
 * pinos_stream_new:
 * @context: a #PinosContext
 * @name: a stream name
 * @properties: (transfer full): stream properties
 *
 * Make a new unconnected #PinosStream
 *
 * Returns: a new unconnected #PinosStream
 */
PinosStream *
pinos_stream_new (PinosContext    *context,
                  const gchar     *name,
                  PinosProperties *props)
{
  PinosStream *stream;

  g_return_val_if_fail (PINOS_IS_CONTEXT (context), NULL);
  g_return_val_if_fail (name != NULL, NULL);

  if (props == NULL) {
    props = pinos_properties_new ("media.name", name, NULL);
  } else if (!pinos_properties_get (props, "media.name")) {
    pinos_properties_set (props, "media.name", name);
  }

  stream = g_object_new (PINOS_TYPE_STREAM,
                       "context", context,
                       "name", name,
                       "properties", props,
                       NULL);

  pinos_properties_free (props);

  return stream;
}

/**
 * pinos_stream_get_state:
 * @stream: a #PinosStream
 *
 * Get the state of @stream.
 *
 * Returns: the state of @stream
 */
PinosStreamState
pinos_stream_get_state (PinosStream *stream)
{
  g_return_val_if_fail (PINOS_IS_STREAM (stream), PINOS_STREAM_STATE_ERROR);

  return stream->priv->state;
}

/**
 * pinos_stream_get_error:
 * @stream: a #PinosStream
 *
 * Get the error of @stream.
 *
 * Returns: the error of @stream or %NULL when there is no error
 */
const GError *
pinos_stream_get_error (PinosStream *stream)
{
  g_return_val_if_fail (PINOS_IS_STREAM (stream), NULL);

  return stream->priv->error;
}

static void
on_received_buffer (PinosPort *port,
                    gpointer user_data)
{
  PinosStream *stream = user_data;

  g_signal_emit (stream, signals[SIGNAL_NEW_BUFFER], 0, NULL);
}

static void
on_port_notify (GObject    *object,
                GParamSpec *pspec,
                gpointer    user_data)
{
  PinosPort *port = PINOS_PORT (object);
  PinosStream *stream = user_data;
  PinosStreamPrivate *priv = stream->priv;

  if (pspec == NULL || strcmp (g_param_spec_get_name (pspec), "format")) {
    g_clear_pointer (&priv->format, g_bytes_unref);
    g_object_get (port, "format", &priv->format, NULL);
    g_object_notify (G_OBJECT (stream), "format");
  }
  if (pspec == NULL || strcmp (g_param_spec_get_name (pspec), "possible-formats")) {
    g_clear_pointer (&priv->possible_formats, g_bytes_unref);
    g_object_get (port, "possible-formats", &priv->possible_formats, NULL);
    g_object_notify (G_OBJECT (stream), "possible-formats");
  }
}

static void
on_port_created (GObject      *source_object,
                 GAsyncResult *res,
                 gpointer      user_data)
{
  PinosStream *stream = user_data;
  PinosStreamPrivate *priv = stream->priv;
  GError *error = NULL;

  g_assert (priv->node ==  PINOS_NODE (source_object));

  priv->port = pinos_node_create_port_finish (priv->node,
                                              res,
                                              &error);
  if (priv->port == NULL)
    goto create_failed;

  on_port_notify (G_OBJECT (priv->port), NULL, stream);
  g_signal_connect (priv->port, "notify", (GCallback) on_port_notify, stream);

  pinos_port_set_received_buffer_cb (priv->port, on_received_buffer, stream, NULL);

  stream_set_state (stream, PINOS_STREAM_STATE_READY, NULL);
  g_object_unref (stream);

  return;

  /* ERRORS */
create_failed:
  {
    g_warning ("failed to create port: %s", error->message);
    stream_set_state (stream, PINOS_STREAM_STATE_ERROR, error);
    g_object_unref (stream);
    return;
  }
}

static void
on_node_created (GObject      *source_object,
                 GAsyncResult *res,
                 gpointer      user_data)
{
  PinosStream *stream = user_data;
  PinosStreamPrivate *priv = stream->priv;
  PinosContext *context = priv->context;
  GError *error = NULL;

  priv->node = pinos_context_create_node_finish (context, res, &error);
  if (priv->node == NULL)
    goto create_failed;

  pinos_node_create_port (priv->node,
                          priv->direction,
                          "client-port",
                          priv->possible_formats,
                          priv->properties,
                          NULL, /* GCancellable *cancellable */
                          on_port_created,
                          stream);
  return;

  /* ERRORS */
create_failed:
  {
    g_warning ("failed to create  node: %s", error->message);
    stream_set_state (stream, PINOS_STREAM_STATE_ERROR, error);
    g_object_unref (stream);
    return;
  }
}

static gboolean
do_connect (PinosStream *stream)
{
  PinosStreamPrivate *priv = stream->priv;
  PinosContext *context = priv->context;

  pinos_context_create_node (context,
                             "client-node",
                             "client-node",
                             priv->properties,
                             NULL, /* GCancellable *cancellable */
                             on_node_created,
                             stream);
  return FALSE;
}

/**
 * pinos_stream_connect:
 * @stream: a #PinosStream
 * @direction: the stream direction
 * @port_path: the port path to connect to or %NULL to get the default port
 * @flags: a #PinosStreamFlags
 * @possible_formats: (transfer full): a #GBytes with possible accepted formats
 *
 * Connect @stream for input or output on @port_path.
 *
 * Returns: %TRUE on success.
 */
gboolean
pinos_stream_connect (PinosStream      *stream,
                      PinosDirection    direction,
                      const gchar      *port_path,
                      PinosStreamFlags  flags,
                      GBytes           *possible_formats)
{
  PinosStreamPrivate *priv;
  PinosContext *context;

  g_return_val_if_fail (PINOS_IS_STREAM (stream), FALSE);
  g_return_val_if_fail (possible_formats != NULL, FALSE);

  priv = stream->priv;
  context = priv->context;
  g_return_val_if_fail (pinos_context_get_state (context) == PINOS_CONTEXT_STATE_READY, FALSE);
  g_return_val_if_fail (pinos_stream_get_state (stream) == PINOS_STREAM_STATE_UNCONNECTED, FALSE);

  priv->direction = direction;
  g_free (priv->path);
  priv->path = g_strdup (port_path);
  if (priv->possible_formats)
    g_bytes_unref (priv->possible_formats);
  priv->possible_formats = possible_formats;
  priv->provide = FALSE;

  stream_set_state (stream, PINOS_STREAM_STATE_CONNECTING, NULL);

  g_main_context_invoke (context->priv->context,
                         (GSourceFunc) do_connect,
                         g_object_ref (stream));

  return TRUE;
}

static gboolean
do_connect_provide (PinosStream *stream)
{
#if 0
  PinosStreamPrivate *priv = stream->priv;
  PinosContext *context = priv->context;

  g_dbus_proxy_call (context->priv->client,
                     "CreateUploadChannel",
                     g_variant_new ("(s@a{sv})",
                       g_bytes_get_data (priv->possible_formats, NULL),
                       pinos_properties_to_variant (priv->properties)),
                     G_DBUS_CALL_FLAGS_NONE,
                     -1,
                     NULL, /* GCancellable *cancellable */
                     on_channel_created,
                     stream);
#endif

  return FALSE;
}

/**
 * pinos_stream_connect_provide:
 * @stream: a #PinosStream
 * @flags: a #PinosStreamFlags
 * @possible_formats: (transfer full): a #GBytes
 *
 * Connect @stream for providing data for a new source.
 *
 * Returns: %TRUE on success.
 */
gboolean
pinos_stream_connect_provide (PinosStream      *stream,
                              PinosStreamFlags  flags,
                              GBytes           *possible_formats)
{
  PinosStreamPrivate *priv;
  PinosContext *context;

  g_return_val_if_fail (PINOS_IS_STREAM (stream), FALSE);
  g_return_val_if_fail (possible_formats != NULL, FALSE);

  priv = stream->priv;
  context = priv->context;
  g_return_val_if_fail (pinos_context_get_state (context) == PINOS_CONTEXT_STATE_READY, FALSE);

  if (priv->possible_formats)
    g_bytes_unref (priv->possible_formats);
  priv->possible_formats = possible_formats;
  priv->provide = TRUE;

  stream_set_state (stream, PINOS_STREAM_STATE_CONNECTING, NULL);

  g_main_context_invoke (context->priv->context,
                         (GSourceFunc) do_connect_provide,
                         g_object_ref (stream));

  return TRUE;
}

static gboolean
do_start (PinosStream *stream)
{
  stream_set_state (stream, PINOS_STREAM_STATE_STREAMING, NULL);
  g_object_unref (stream);

  return FALSE;
}

/**
 * pinos_stream_start:
 * @stream: a #PinosStream
 * @format: (transfer full): a #GBytes with format
 * @mode: a #PinosStreamMode
 *
 * Start capturing from @stream in @format.
 *
 * When @mode is #PINOS_STREAM_MODE_SOCKET, you should connect to the notify::socket
 * signal to obtain a readable socket with metadata and data.
 *
 * When @mode is #PINOS_STREAM_MODE_BUFFER, you should connect to the new-buffer
 * signal and use pinos_stream_capture_buffer() to get the latest metadata and
 * data.
 *
 * Returns: %TRUE on success.
 */
gboolean
pinos_stream_start (PinosStream     *stream,
                    GBytes          *format,
                    PinosStreamMode  mode)
{
  PinosStreamPrivate *priv;

  g_return_val_if_fail (PINOS_IS_STREAM (stream), FALSE);

  priv = stream->priv;
  g_return_val_if_fail (priv->state == PINOS_STREAM_STATE_READY, FALSE);

  priv->mode = mode;
  priv->format = format;

  stream_set_state (stream, PINOS_STREAM_STATE_STARTING, NULL);

  g_main_context_invoke (priv->context->priv->context,
                         (GSourceFunc) do_start,
                         g_object_ref (stream));

  return TRUE;
}

static gboolean
do_stop (PinosStream *stream)
{
  stream_set_state (stream, PINOS_STREAM_STATE_READY, NULL);
  g_object_unref (stream);

  return FALSE;
}

/**
 * pinos_stream_stop:
 * @stream: a #PinosStream
 *
 * Stop capturing from @stream.
 *
 * Returns: %TRUE on success.
 */
gboolean
pinos_stream_stop (PinosStream *stream)
{
  PinosStreamPrivate *priv;

  g_return_val_if_fail (PINOS_IS_STREAM (stream), FALSE);

  priv = stream->priv;
  g_return_val_if_fail (priv->state == PINOS_STREAM_STATE_STREAMING, FALSE);

  g_main_context_invoke (priv->context->priv->context,
                         (GSourceFunc) do_stop,
                         g_object_ref (stream));

  return TRUE;
}

static gboolean
do_disconnect (PinosStream *stream)
{
  PinosStreamPrivate *priv = stream->priv;

  pinos_node_remove (priv->node);

  return FALSE;
}

/**
 * pinos_stream_disconnect:
 * @stream: a #PinosStream
 *
 * Disconnect @stream.
 *
 * Returns: %TRUE on success
 */
gboolean
pinos_stream_disconnect (PinosStream *stream)
{
  PinosStreamPrivate *priv;
  PinosContext *context;

  g_return_val_if_fail (PINOS_IS_STREAM (stream), FALSE);
  priv = stream->priv;
  g_return_val_if_fail (priv->state >= PINOS_STREAM_STATE_READY, FALSE);
  g_return_val_if_fail (priv->node != NULL, FALSE);
  context = priv->context;
  g_return_val_if_fail (pinos_context_get_state (context) >= PINOS_CONTEXT_STATE_READY, FALSE);
  g_return_val_if_fail (!priv->disconnecting, FALSE);

  priv->disconnecting = TRUE;

  g_main_context_invoke (context->priv->context,
                         (GSourceFunc) do_disconnect,
                         g_object_ref (stream));

  return TRUE;
}

/**
 * pinos_stream_peek_buffer:
 * @stream: a #PinosStream
 *
 * Get the current buffer from @stream. This function should be called from
 * the new-buffer signal callback.
 *
 * Returns: a #PinosBuffer or %NULL when there is no buffer.
 */
PinosBuffer *
pinos_stream_peek_buffer (PinosStream  *stream)
{
  PinosStreamPrivate *priv;

  g_return_val_if_fail (PINOS_IS_STREAM (stream), FALSE);

  priv = stream->priv;
  //g_return_val_if_fail (priv->state == PINOS_STREAM_STATE_STREAMING, FALSE);

  return pinos_port_peek_buffer (priv->port);
}

/**
 * pinos_stream_buffer_builder_init:
 * @stream: a #PinosStream
 * @builder: a #PinosBufferBuilder
 *
 * Get a #PinosBufferBuilder for @stream.
 *
 * Returns: a #PinosBuffer or %NULL when there is no buffer.
 */
void
pinos_stream_buffer_builder_init (PinosStream  *stream, PinosBufferBuilder *builder)
{
  PinosStreamPrivate *priv;

  g_return_if_fail (PINOS_IS_STREAM (stream));
  priv = stream->priv;

  pinos_port_buffer_builder_init (priv->port, builder);
}

/**
 * pinos_stream_send_buffer:
 * @stream: a #PinosStream
 * @buffer: a #PinosBuffer
 *
 * Send a buffer to @stream.
 *
 * For provider streams, this function should be called whenever there is a new frame
 * available.
 *
 * For capture streams, this functions should be called for each fd-payload that
 * should be released.
 *
 * Returns: %TRUE when @buffer was handled
 */
gboolean
pinos_stream_send_buffer (PinosStream *stream,
                          PinosBuffer *buffer)
{
  PinosStreamPrivate *priv;
  GError *error = NULL;

  g_return_val_if_fail (PINOS_IS_STREAM (stream), FALSE);
  g_return_val_if_fail (buffer != NULL, FALSE);

  priv = stream->priv;
  g_return_val_if_fail (priv->state == PINOS_STREAM_STATE_STREAMING, FALSE);

  if (!pinos_port_send_buffer (priv->port, buffer, &error))
    goto send_error;

  return TRUE;

  /* ERRORS */
send_error:
  {
    g_warning ("failed to send message: %s", error->message);
    stream_set_state (stream, PINOS_STREAM_STATE_ERROR, error);
    g_clear_error (&error);
    return FALSE;
  }
}