Merge 21611 - Implemented proper pausethenseek behaviour for the media pipeli...

media/filters/video_renderer_base.h

 // Copyright (c) 2009 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.
 
 // VideoRendererBase creates its own thread for the sole purpose of timing frame
 // presentation.  It handles reading from the decoder and stores the results in
 // a queue of decoded frames, calling OnFrameAvailable() on subclasses to notify
 // when a frame is ready to display.
 //
 // The media filter methods Initialize(), Stop(), SetPlaybackRate() and Seek()
@@ skipping 19 matching lines @@
  public:
   VideoRendererBase();
   virtual ~VideoRendererBase();
 
   // Helper method for subclasses to parse out video-related information from
   // a MediaFormat.  Returns true if |width_out| and |height_out| were assigned.
   static bool ParseMediaFormat(const MediaFormat& media_format,
                                int* width_out, int* height_out);
 
   // MediaFilter implementation.
+  virtual void Play(FilterCallback* callback);
+  virtual void Pause(FilterCallback* callback);
   virtual void Stop();
   virtual void SetPlaybackRate(float playback_rate);
   virtual void Seek(base::TimeDelta time, FilterCallback* callback);
 
   // VideoRenderer implementation.
   virtual void Initialize(VideoDecoder* decoder, FilterCallback* callback);
 
   // PlatformThread::Delegate implementation.
   virtual void ThreadMain();
 
@@ skipping 16 matching lines @@
 
   // Subclass interface.  Called when a new frame is ready for display, which
   // can be accessed via GetCurrentFrame().
   //
   // Implementors should avoid doing any sort of heavy work in this method and
   // instead post a task to a common/worker thread to handle rendering.  Slowing
   // down the video thread may result in losing synchronization with audio.
   virtual void OnFrameAvailable() = 0;
 
  private:
-  // Read complete callback from video decoder.
+  // Read complete callback from video decoder and decrements |pending_reads_|.
   void OnReadComplete(VideoFrame* frame);
 
-  // Helper method that schedules an asynchronous read from the decoder.
+  // Helper method that schedules an asynchronous read from the decoder and
+  // increments |pending_reads_|.
   //
   // Safe to call from any thread.
-  void ScheduleRead();
+  void ScheduleRead_Locked();
 
-  // Called by ThreadMain() to handle preroll.  Returns false if the thread
-  // should exit due to Stop() being called.
-  bool WaitForInitialized();
+  // Calculates the duration to sleep for based on |current_frame_|'s timestamp,
+  // the next frame timestamp (may be NULL), and the provided playback rate.
+  //
+  // We don't use |playback_rate_| to avoid locking.
+  base::TimeDelta CalculateSleepDuration(VideoFrame* next_frame,
+                                         float playback_rate);
+
+  // Allocates YV12 frame based on |width_| and |height_|, and sets its data to
+  // the YUV equivalent of RGB(0,0,0).
+  void CreateBlackFrame(scoped_refptr<VideoFrame>* frame_out);
+
+  // Used for accessing data members.
+  Lock lock_;
 
   scoped_refptr<VideoDecoder> decoder_;
 
+  // Video dimensions parsed from the decoder's media format.
+  int width_;
+  int height_;
+
   // Queue of incoming frames as well as the current frame since the last time
   // OnFrameAvailable() was called.
   typedef std::deque< scoped_refptr<VideoFrame> > VideoFrameQueue;
   VideoFrameQueue frames_;
   scoped_refptr<VideoFrame> current_frame_;
 
-  // Used for accessing |frames_|.
-  Lock lock_;
-
   // Used to signal |thread_| as frames are added to |frames_|.  Rule of thumb:
   // always check |state_| to see if it was set to STOPPED after waking up!
   ConditionVariable frame_available_;
 
   // Simple state tracking variable.
   enum State {
-    UNINITIALIZED,
-    INITIALIZING,
-    INITIALIZED,
-    STOPPED,
-    ERRORED,
+    kUninitialized,
+    kPaused,
+    kSeeking,
+    kPlaying,
+    kStopped,
+    kError,
   };
   State state_;
 
   // Video thread handle.
   PlatformThreadHandle thread_;
 
   // Previous time returned from the pipeline.
   base::TimeDelta previous_time_;
 
+  // Keeps track of our pending reads.  We *must* have no pending reads before
+  // executing the pause callback, otherwise we breach the contract that all
+  // filters are idling.
+  //
+  // We use size_t since we compare against std::deque::size().
+  size_t pending_reads_;
+
   float playback_rate_;
 
   // Filter callbacks.
-  scoped_ptr<FilterCallback> initialize_callback_;
+  scoped_ptr<FilterCallback> pause_callback_;
+  scoped_ptr<FilterCallback> seek_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(VideoRendererBase);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_VIDEO_RENDERER_BASE_H_