1// Copyright 2014 The Chromium Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style license that can be 3// found in the LICENSE file. 4 5#ifndef MEDIA_BASE_WALL_CLOCK_TIME_SOURCE_H_ 6#define MEDIA_BASE_WALL_CLOCK_TIME_SOURCE_H_ 7 8#include "base/memory/scoped_ptr.h" 9#include "base/synchronization/lock.h" 10#include "media/base/media_export.h" 11#include "media/base/time_source.h" 12 13namespace base { 14class TickClock; 15} 16 17namespace media { 18 19// A time source that uses interpolation based on the system clock. 20class MEDIA_EXPORT WallClockTimeSource : public TimeSource { 21 public: 22 WallClockTimeSource(); 23 virtual ~WallClockTimeSource(); 24 25 // TimeSource implementation. 26 virtual void StartTicking() OVERRIDE; 27 virtual void StopTicking() OVERRIDE; 28 virtual void SetPlaybackRate(float playback_rate) OVERRIDE; 29 virtual void SetMediaTime(base::TimeDelta time) OVERRIDE; 30 virtual base::TimeDelta CurrentMediaTime() OVERRIDE; 31 virtual base::TimeDelta CurrentMediaTimeForSyncingVideo() OVERRIDE; 32 33 void SetTickClockForTesting(scoped_ptr<base::TickClock> tick_clock); 34 35 private: 36 base::TimeDelta CurrentMediaTime_Locked(); 37 38 scoped_ptr<base::TickClock> tick_clock_; 39 bool ticking_; 40 41 // While ticking we can interpolate the current media time by measuring the 42 // delta between our reference ticks and the current system ticks and scaling 43 // that time by the playback rate. 44 float playback_rate_; 45 base::TimeDelta base_time_; 46 base::TimeTicks reference_wall_ticks_; 47 48 // TODO(scherkus): Remove internal locking from this class after access to 49 // Renderer::CurrentMediaTime() is single threaded http://crbug.com/370634 50 base::Lock lock_; 51 52 DISALLOW_COPY_AND_ASSIGN(WallClockTimeSource); 53}; 54 55} // namespace media 56 57#endif // MEDIA_BASE_WALL_CLOCK_TIME_SOURCE_H_ 58