decode_synchronizer.h | Explore in Territory

/*
 *  Copyright (c) 2022 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#ifndef VIDEO_DECODE_SYNCHRONIZER_H_
#define VIDEO_DECODE_SYNCHRONIZER_H_

#include <stdint.h>

#include <functional>
#include <memory>
#include <set>
#include <utility>

#include "absl/types/optional.h"
#include "api/metronome/metronome.h"
#include "api/sequence_checker.h"
#include "api/task_queue/task_queue_base.h"
#include "api/units/timestamp.h"
#include "rtc_base/checks.h"
#include "rtc_base/thread_annotations.h"
#include "video/frame_decode_scheduler.h"
#include "video/frame_decode_timing.h"

namespace webrtc {

// DecodeSynchronizer synchronizes the frame scheduling by coalescing decoding
// on the metronome.
//
// A video receive stream can use the DecodeSynchronizer by receiving a
// FrameDecodeScheduler instance with `CreateSynchronizedFrameScheduler()`.
// This instance implements FrameDecodeScheduler and can be used as a normal
// scheduler. This instance is owned by the receive stream, and is borrowed by
// the DecodeSynchronizer. The DecodeSynchronizer will stop borrowing the
// instance when `FrameDecodeScheduler::Stop()` is called, after which the
// scheduler may be destroyed by the receive stream.
//
// When a frame is scheduled for decode by a receive stream using the
// DecodeSynchronizer, it will instead be executed on the metronome during the
// tick interval where `max_decode_time` occurs. For example, if a frame is
// scheduled for decode in 50ms and the tick interval is 20ms, then the frame
// will be released for decoding in 2 ticks. See below for illustration,
//
// In the case where the decode time is in the past, or must occur before the
// next metronome tick then the frame will be released right away, allowing a
// delayed stream to catch up quickly.
//
// DecodeSynchronizer is single threaded - all method calls must run on the
// `worker_queue_`.
class DecodeSynchronizer { … };

}  // namespace webrtc

#endif  // VIDEO_DECODE_SYNCHRONIZER_H_
chromium/third_party/webrtc/video/decode_synchronizer.h
