chromecast/media/cma/base/buffering_controller.h

   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 CHROMECAST_MEDIA_CMA_BASE_BUFFERING_CONTROLLER_H
   6 #define CHROMECAST_MEDIA_CMA_BASE_BUFFERING_CONTROLLER_H
   7
   8 #include <list>
   9 #include <string>
  10
  11 #include "base/callback.h"
  12 #include "base/macros.h"
  13 #include "base/memory/ref_counted.h"
  14 #include "base/memory/weak_ptr.h"
  15 #include "base/threading/thread_checker.h"
  16 #include "base/time/time.h"
  17
  18 namespace chromecast {
  19 namespace media {
  20 class BufferingConfig;
  21 class BufferingState;
  22
  23 class BufferingController {
  24  public:
  25   typedef base::Callback<void(bool)> BufferingNotificationCB;
  26
  27   // Creates a buffering controller where the conditions to trigger rebuffering
  28   // are given by |config|. The whole point of the buffering controller is to
  29   // derive a single buffering state from the buffering state of various
  30   // streams.
  31   // |buffering_notification_cb| is a callback invoked to inform about possible
  32   // changes of the buffering state.
  33   BufferingController(
  34       const scoped_refptr<BufferingConfig>& config,
  35       const BufferingNotificationCB& buffering_notification_cb);
  36   ~BufferingController();
  37
  38   // Creates a buffering state for one stream. This state is added to the list
  39   // of streams monitored by the buffering controller.
  40   scoped_refptr<BufferingState> AddStream(const std::string& stream_id);
  41
  42   // Sets the playback time.
  43   void SetMediaTime(base::TimeDelta time);
  44
  45   // Returns the maximum media time available for rendering.
  46   // Return kNoTimestamp() if unknown.
  47   base::TimeDelta GetMaxRenderingTime() const;
  48
  49   // Returns whether there is an active buffering phase.
  50   bool IsBuffering() const { return is_buffering_; }
  51
  52   // Resets the buffering controller. This includes removing all the streams
  53   // that were previously added.
  54   void Reset();
  55
  56  private:
  57   // Invoked each time the buffering state of one of the streams has changed.
  58   // If |force_notification| is set, |buffering_notification_cb_| is invoked
  59   // regardless whether the buffering state has changed or not.
  60   // If |buffering_timeout| is set, then the condition to leave the buffering
  61   // state is relaxed (we don't want to wait more).
  62   void OnBufferingStateChanged(bool force_notification,
  63                                bool buffering_timeout);
  64
  65   // Updates the high buffer level threshold to |high_level_threshold|
  66   // if needed.
  67   // This condition is triggered when one of the stream reached its maximum
  68   // capacity. In that case, to avoid possible race condition (the buffering
  69   // controller waits for more data to come but the buffer is to small to
  70   // accomodate additional data), the thresholds in |config_| are adjusted
  71   // accordingly.
  72   void UpdateHighLevelThreshold(base::TimeDelta high_level_threshold);
  73
  74   // Determines the overall buffer level based on the buffer level of each
  75   // stream.
  76   bool IsHighBufferLevel();
  77   bool IsLowBufferLevel();
  78
  79   // Logs the state of the buffering controller.
  80   void DumpState() const;
  81
  82   base::ThreadChecker thread_checker_;
  83
  84   // Settings used to determine when to start/stop buffering.
  85   scoped_refptr<BufferingConfig> config_;
  86
  87   // Callback invoked each time there is a change of the buffering state.
  88   BufferingNotificationCB buffering_notification_cb_;
  89
  90   // State of the buffering controller.
  91   bool is_buffering_;
  92
  93   // Start time of a re-buffering phase.
  94   base::Time begin_buffering_time_;
  95   bool initial_buffering_;
  96
  97   // Buffering level for each individual stream.
  98   typedef std::list<scoped_refptr<BufferingState> > StreamList;
  99   StreamList stream_list_;
 100
 101   base::WeakPtr<BufferingController> weak_this_;
 102   base::WeakPtrFactory<BufferingController> weak_factory_;
 103
 104   DISALLOW_COPY_AND_ASSIGN(BufferingController);
 105 };
 106
 107 }  // namespace media
 108 }  // namespace chromecast
 109
 110 #endif  // CHROMECAST_MEDIA_CMA_BASE_BUFFERING_CONTROLLER_H