public/lib/media/fidl/timeline_controller.fidl

// Copyright 2016 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

module media;

import "lib/media/fidl/timelines.fidl";

// Timing controller for a media graph.
interface MediaTimelineController {
  // Associates a control point with the controller.
  AddControlPoint(MediaTimelineControlPoint control_point);

  // Gets a timeline control point interface for the controller.
  GetControlPoint(MediaTimelineControlPoint& control_point);
};

// Media graph component controlled by a MediaTimelineController.
interface MediaTimelineControlPoint {
  const uint64 kInitialStatus = 0;

  // Gets the status. To get the status immediately, call
  // GetStatus(kInitialStatus). To get updates thereafter, pass the version sent
  // in the previous callback.
  GetStatus(uint64 version_last_seen) =>
      (uint64 version, MediaTimelineControlPointStatus status);

  // Gets a timeline consumer interface for the control point.
  GetTimelineConsumer(TimelineConsumer& timeline_consumer);

  // Specifies the range of PTS values to be accepted at this control point for
  // the given program.
  SetProgramRange(uint64 program, int64 min_pts, int64 max_pts);

  // Signals that the control point should prepare for a timeline transition
  // away from zero rate (stopped). The response indicates that the control
  // point is ready for the transition.
  // TODO(dalesat): Include a rate so the renderer won't starve on fast play.
  Prime() => ();
};

// Status returned by MediaTimelineControlPoint's GetStatus method.
struct MediaTimelineControlPointStatus {
  // Current timeline transform.
  TimelineTransform timeline_transform;

  // Indicates whether presentation has reached end-of-stream.
  bool end_of_stream;
};