mojo/services/media/core/interfaces/timeline_controller.mojom

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

[DartPackage="mojo_services"]
module mojo.media;

import "mojo/services/media/common/interfaces/timelines.mojom";

// Timing controller for a media graph.
interface MediaTimelineController {
  const int64 kUnspecifiedTime = 0x7fffffffffffffff;
  const uint64 kInitialStatus = 0;

  // Associates a control site with the controller.
  AddControlSite(MediaTimelineControlSite control_site);

  // 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, MediaTimelineControllerStatus status);

  // Sets the timeline transform at the indicated effective time. At least one
  // of the effective_*_time values must be kUnspecifiedTime. If both are
  // kUnspecifiedTime, the requested change is implemented as soon as possible.
  // effective_subject_time can only be specified if the current subject_delta
  // isn’t zero. reference_delta may not be zero. subject_time may be
  // kUnspecifiedTime to indicate that the new transform subject_time should
  // be inferred from the effective time. The reference time for the new
  // transform (the reference time that will correspond to the specified or
  // inferred subject_time) is always inferred from the effective time. The
  // callback is called at the effective time or when a pending operation is
  // cancelled due to a subsequent call, in which case the 'completed' value is
  // false.
  SetTimelineTransform(
      int64 subject_time,
      uint32 subject_delta,
      uint32 reference_delta,
      int64 effective_subject_time,
      int64 effective_reference_time) => (bool completed);

  // Gets a timeline control site interface for the controller.
  GetControlSite(MediaTimelineControlSite& control_site);
};

// Status returned by MediaTimelineController's GetStatus method.
struct MediaTimelineControllerStatus {
  // Current timeline transform.
  mojo.TimelineTransform timeline_transform;

  // Whether end of stream was encountered.
  bool end_of_stream;
};

// Media graph component controlled by a MediaTimelineController.
interface MediaTimelineControlSite {
  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, MediaTimelineControlSiteStatus status);

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

// Status returned by MediaTimelineControlSite's GetStatus method.
struct MediaTimelineControlSiteStatus {
  // Whether end of stream was encountered.
  bool end_of_stream;

  // Whether the site is starving.
  bool starving;
};