media/filters/video_renderer_base.h

   1 // Copyright (c) 2012 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_RENDERER_BASE_H_
   6 #define MEDIA_FILTERS_VIDEO_RENDERER_BASE_H_
   7
   8 #include <deque>
   9
  10 #include "base/memory/ref_counted.h"
  11 #include "base/memory/scoped_vector.h"
  12 #include "base/memory/weak_ptr.h"
  13 #include "base/synchronization/condition_variable.h"
  14 #include "base/synchronization/lock.h"
  15 #include "base/threading/platform_thread.h"
  16 #include "media/base/decryptor.h"
  17 #include "media/base/demuxer_stream.h"
  18 #include "media/base/pipeline_status.h"
  19 #include "media/base/video_decoder.h"
  20 #include "media/base/video_frame.h"
  21 #include "media/base/video_renderer.h"
  22 #include "media/filters/video_frame_stream.h"
  23
  24 namespace base {
  25 class MessageLoopProxy;
  26 }
  27
  28 namespace media {
  29
  30 // VideoRendererBase creates its own thread for the sole purpose of timing frame
  31 // presentation.  It handles reading from the VideoFrameStream and stores the
  32 // results in a queue of decoded frames and executing a callback when a frame is
  33 // ready for rendering.
  34 class MEDIA_EXPORT VideoRendererBase
  35     : public VideoRenderer,
  36       public base::PlatformThread::Delegate {
  37  public:
  38   typedef base::Callback<void(const scoped_refptr<VideoFrame>&)> PaintCB;
  39   typedef base::Callback<void(bool)> SetOpaqueCB;
  40
  41   // Maximum duration of the last frame.
  42   static base::TimeDelta kMaxLastFrameDuration();
  43
  44   // |decoders| contains the VideoDecoders to use when initializing.
  45   //
  46   // |paint_cb| is executed on the video frame timing thread whenever a new
  47   // frame is available for painting.
  48   //
  49   // |set_opaque_cb| is executed when the renderer is initialized to inform
  50   // the player whether the decoded output will be opaque or not.
  51   //
  52   // Implementors should avoid doing any sort of heavy work in this method and
  53   // instead post a task to a common/worker thread to handle rendering.  Slowing
  54   // down the video thread may result in losing synchronization with audio.
  55   //
  56   // Setting |drop_frames_| to true causes the renderer to drop expired frames.
  57   VideoRendererBase(const scoped_refptr<base::MessageLoopProxy>& message_loop,
  58                     ScopedVector<VideoDecoder> decoders,
  59                     const SetDecryptorReadyCB& set_decryptor_ready_cb,
  60                     const PaintCB& paint_cb,
  61                     const SetOpaqueCB& set_opaque_cb,
  62                     bool drop_frames);
  63   virtual ~VideoRendererBase();
  64
  65   // VideoRenderer implementation.
  66   virtual void Initialize(DemuxerStream* stream,
  67                           const PipelineStatusCB& init_cb,
  68                           const StatisticsCB& statistics_cb,
  69                           const TimeCB& max_time_cb,
  70                           const NaturalSizeChangedCB& size_changed_cb,
  71                           const base::Closure& ended_cb,
  72                           const PipelineStatusCB& error_cb,
  73                           const TimeDeltaCB& get_time_cb,
  74                           const TimeDeltaCB& get_duration_cb) OVERRIDE;
  75   virtual void Play(const base::Closure& callback) OVERRIDE;
  76   virtual void Pause(const base::Closure& callback) OVERRIDE;
  77   virtual void Flush(const base::Closure& callback) OVERRIDE;
  78   virtual void Preroll(base::TimeDelta time,
  79                        const PipelineStatusCB& cb) OVERRIDE;
  80   virtual void Stop(const base::Closure& callback) OVERRIDE;
  81   virtual void SetPlaybackRate(float playback_rate) OVERRIDE;
  82
  83   // PlatformThread::Delegate implementation.
  84   virtual void ThreadMain() OVERRIDE;
  85
  86  private:
  87   // Callback for |video_frame_stream_| initialization.
  88   void OnVideoFrameStreamInitialized(bool success, bool has_alpha);
  89
  90   // Callback for |video_frame_stream_| to deliver decoded video frames and
  91   // report video decoding status.
  92   void FrameReady(VideoFrameStream::Status status,
  93                   const scoped_refptr<VideoFrame>& frame);
  94
  95   // Helper method for adding a frame to |ready_frames_|.
  96   void AddReadyFrame_Locked(const scoped_refptr<VideoFrame>& frame);
  97
  98   // Helper method that schedules an asynchronous read from the
  99   // |video_frame_stream_| as long as there isn't a pending read and we have
 100   // capacity.
 101   void AttemptRead();
 102   void AttemptRead_Locked();
 103
 104   // Called when VideoFrameStream::Reset() completes.
 105   void OnVideoFrameStreamResetDone();
 106
 107   // Calculates the duration to sleep for based on |last_timestamp_|,
 108   // the next frame timestamp (may be NULL), and the provided playback rate.
 109   //
 110   // We don't use |playback_rate_| to avoid locking.
 111   base::TimeDelta CalculateSleepDuration(
 112       const scoped_refptr<VideoFrame>& next_frame,
 113       float playback_rate);
 114
 115   // Helper function that flushes the buffers when a Stop() or error occurs.
 116   void DoStopOrError_Locked();
 117
 118   // Runs |paint_cb_| with the next frame from |ready_frames_|, updating
 119   // |last_natural_size_| and running |size_changed_cb_| if the natural size
 120   // changes.
 121   //
 122   // A read is scheduled to replace the frame.
 123   void PaintNextReadyFrame_Locked();
 124
 125   // Drops the next frame from |ready_frames_| and runs |statistics_cb_|.
 126   //
 127   // A read is scheduled to replace the frame.
 128   void DropNextReadyFrame_Locked();
 129
 130   void TransitionToPrerolled_Locked();
 131
 132   // Runs |statistics_cb_| with |frames_decoded_| and |frames_dropped_|, resets
 133   // them to 0, and then waits on |frame_available_| for up to the
 134   // |wait_duration|.
 135   void UpdateStatsAndWait_Locked(base::TimeDelta wait_duration);
 136
 137   scoped_refptr<base::MessageLoopProxy> message_loop_;
 138   base::WeakPtrFactory<VideoRendererBase> weak_factory_;
 139   base::WeakPtr<VideoRendererBase> weak_this_;
 140
 141   // Used for accessing data members.
 142   base::Lock lock_;
 143
 144   // Provides video frames to VideoRendererBase.
 145   VideoFrameStream video_frame_stream_;
 146
 147   // Queue of incoming frames yet to be painted.
 148   typedef std::deque<scoped_refptr<VideoFrame> > VideoFrameQueue;
 149   VideoFrameQueue ready_frames_;
 150
 151   // Keeps track of whether we received the end of stream buffer.
 152   bool received_end_of_stream_;
 153
 154   // Used to signal |thread_| as frames are added to |frames_|.  Rule of thumb:
 155   // always check |state_| to see if it was set to STOPPED after waking up!
 156   base::ConditionVariable frame_available_;
 157
 158   // State transition Diagram of this class:
 159   //       [kUninitialized] -------> [kError]
 160   //              |
 161   //              | Initialize()
 162   //        [kInitializing]
 163   //              |
 164   //              V
 165   //   +------[kFlushed]<---------------OnVideoFrameStreamResetDone()
 166   //   |          | Preroll() or upon               ^
 167   //   |          V got first frame            [kFlushing]
 168   //   |      [kPrerolling]                         ^
 169   //   |          |                                 | Flush()
 170   //   |          V Got enough frames               |
 171   //   |      [kPrerolled]---------------------->[kPaused]
 172   //   |          |                Pause()          ^
 173   //   |          V Play()                          |
 174   //   |       [kPlaying]---------------------------|
 175   //   |          |                Pause()          ^
 176   //   |          V Receive EOF frame.              | Pause()
 177   //   |       [kEnded]-----------------------------+
 178   //   |                                            ^
 179   //   |                                            |
 180   //   +-----> [kStopped]                 [Any state other than]
 181   //                                      [kUninitialized/kError]
 182
 183   // Simple state tracking variable.
 184   enum State {
 185     kUninitialized,
 186     kInitializing,
 187     kPrerolled,
 188     kPaused,
 189     kFlushing,
 190     kFlushed,
 191     kPrerolling,
 192     kPlaying,
 193     kEnded,
 194     kStopped,
 195     kError,
 196   };
 197   State state_;
 198
 199   // Video thread handle.
 200   base::PlatformThreadHandle thread_;
 201
 202   // Keep track of the outstanding read on the VideoFrameStream. Flushing can
 203   // only complete once the read has completed.
 204   bool pending_read_;
 205
 206   bool drop_frames_;
 207
 208   float playback_rate_;
 209
 210   // Playback operation callbacks.
 211   base::Closure flush_cb_;
 212   PipelineStatusCB preroll_cb_;
 213
 214   // Event callbacks.
 215   PipelineStatusCB init_cb_;
 216   StatisticsCB statistics_cb_;
 217   TimeCB max_time_cb_;
 218   NaturalSizeChangedCB size_changed_cb_;
 219   base::Closure ended_cb_;
 220   PipelineStatusCB error_cb_;
 221   TimeDeltaCB get_time_cb_;
 222   TimeDeltaCB get_duration_cb_;
 223
 224   base::TimeDelta preroll_timestamp_;
 225
 226   // Embedder callback for notifying a new frame is available for painting.
 227   PaintCB paint_cb_;
 228
 229   // Callback to execute to inform the player if the decoded output is opaque.
 230   SetOpaqueCB set_opaque_cb_;
 231
 232   // The last natural size |size_changed_cb_| was called with.
 233   //
 234   // TODO(scherkus): WebMediaPlayerImpl should track this instead of plumbing
 235   // this through Pipeline. The one tricky bit might be guaranteeing we deliver
 236   // the size information before we reach HAVE_METADATA.
 237   gfx::Size last_natural_size_;
 238
 239   // The timestamp of the last frame removed from the |ready_frames_| queue,
 240   // either for calling |paint_cb_| or for dropping. Set to kNoTimestamp()
 241   // during flushing.
 242   base::TimeDelta last_timestamp_;
 243
 244   // Keeps track of the number of frames decoded and dropped since the
 245   // last call to |statistics_cb_|. These must be accessed under lock.
 246   int frames_decoded_;
 247   int frames_dropped_;
 248
 249   DISALLOW_COPY_AND_ASSIGN(VideoRendererBase);
 250 };
 251
 252 }  // namespace media
 253
 254 #endif  // MEDIA_FILTERS_VIDEO_RENDERER_BASE_H_