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      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_FILTERS_VIDEO_FRAME_SCHEDULER_IMPL_H_
      6 #define MEDIA_FILTERS_VIDEO_FRAME_SCHEDULER_IMPL_H_
      7 
      8 #include <queue>
      9 
     10 #include "base/memory/ref_counted.h"
     11 #include "base/timer/timer.h"
     12 #include "media/filters/video_frame_scheduler.h"
     13 
     14 namespace base {
     15 class SingleThreadTaskRunner;
     16 class TickClock;
     17 }
     18 
     19 namespace media {
     20 
     21 // A scheduler that uses delayed tasks on a task runner for timing the display
     22 // of video frames.
     23 //
     24 // Single threaded. Calls must be on |task_runner|.
     25 class MEDIA_EXPORT VideoFrameSchedulerImpl : public VideoFrameScheduler {
     26  public:
     27   typedef base::Callback<void(const scoped_refptr<VideoFrame>&)> DisplayCB;
     28 
     29   // |task_runner| is used for scheduling the delayed tasks.
     30   // |display_cb| is run when a frame is to be displayed.
     31   VideoFrameSchedulerImpl(
     32       const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
     33       const DisplayCB& display_cb);
     34   virtual ~VideoFrameSchedulerImpl();
     35 
     36   // VideoFrameScheduler implementation.
     37   virtual void ScheduleVideoFrame(const scoped_refptr<VideoFrame>& frame,
     38                                   base::TimeTicks wall_ticks,
     39                                   const DoneCB& done_cb) OVERRIDE;
     40   virtual void Reset() OVERRIDE;
     41 
     42   void SetTickClockForTesting(scoped_ptr<base::TickClock> tick_clock);
     43 
     44  private:
     45   void ResetTimerIfNecessary();
     46   void OnTimerFired();
     47 
     48   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
     49   DisplayCB display_cb_;
     50   scoped_ptr<base::TickClock> tick_clock_;
     51   base::OneShotTimer<VideoFrameScheduler> timer_;
     52 
     53   struct PendingFrame {
     54     PendingFrame(const scoped_refptr<VideoFrame>& frame,
     55                  base::TimeTicks wall_ticks,
     56                  const DoneCB& done_cb);
     57     ~PendingFrame();
     58 
     59     // For use with std::priority_queue<T>.
     60     bool operator<(const PendingFrame& other) const;
     61 
     62     scoped_refptr<VideoFrame> frame;
     63     base::TimeTicks wall_ticks;
     64     DoneCB done_cb;
     65   };
     66   typedef std::priority_queue<PendingFrame> PendingFrameQueue;
     67   PendingFrameQueue pending_frames_;
     68 
     69   DISALLOW_COPY_AND_ASSIGN(VideoFrameSchedulerImpl);
     70 };
     71 
     72 }  // namespace media
     73 
     74 #endif  // MEDIA_FILTERS_VIDEO_FRAME_SCHEDULER_IMPL_H_
     75