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// Copyright 2014 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.
#ifndef MEDIA_BASE_WALL_CLOCK_TIME_SOURCE_H_
#define MEDIA_BASE_WALL_CLOCK_TIME_SOURCE_H_
#include "base/macros.h"
#include "base/synchronization/lock.h"
#include "base/thread_annotations.h"
#include "base/time/default_tick_clock.h"
#include "media/base/media_export.h"
#include "media/base/time_source.h"
namespace media {
// A time source that uses interpolation based on the system clock.
class MEDIA_EXPORT WallClockTimeSource : public TimeSource {
public:
WallClockTimeSource();
~WallClockTimeSource() override;
// TimeSource implementation.
void StartTicking() override;
void StopTicking() override;
void SetPlaybackRate(double playback_rate) override;
void SetMediaTime(base::TimeDelta time) override;
base::TimeDelta CurrentMediaTime() override;
bool GetWallClockTimes(
const std::vector<base::TimeDelta>& media_timestamps,
std::vector<base::TimeTicks>* wall_clock_times) override;
void SetTickClockForTesting(const base::TickClock* tick_clock);
private:
base::TimeDelta CurrentMediaTime_Locked() EXCLUSIVE_LOCKS_REQUIRED(lock_);
// Allow for an injectable tick clock for testing.
const base::TickClock* tick_clock_ GUARDED_BY(lock_);
bool ticking_ GUARDED_BY(lock_);
// While ticking we can interpolate the current media time by measuring the
// delta between our reference ticks and the current system ticks and scaling
// that time by the playback rate.
double playback_rate_ GUARDED_BY(lock_);
base::TimeDelta base_timestamp_ GUARDED_BY(lock_);
base::TimeTicks reference_time_ GUARDED_BY(lock_);
// TODO(scherkus): Remove internal locking from this class after access to
// Renderer::CurrentMediaTime() is single threaded http://crbug.com/370634
base::Lock lock_;
DISALLOW_COPY_AND_ASSIGN(WallClockTimeSource);
};
} // namespace media
#endif // MEDIA_BASE_WALL_CLOCK_TIME_SOURCE_H_
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