Allow media track switching.

media/renderers/renderer_impl.h

 // Copyright 2014 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.
 
 #ifndef MEDIA_RENDERERS_RENDERER_IMPL_H_
 #define MEDIA_RENDERERS_RENDERER_IMPL_H_
 
 #include <list>
 #include <memory>
 #include <vector>
@@ skipping 88 matching lines @@
   void OnAudioRendererInitializeDone(PipelineStatus status);
   void InitializeVideoRenderer();
   void OnVideoRendererInitializeDone(PipelineStatus status);
 
   // Helper functions and callbacks for Flush().
   void FlushAudioRenderer();
   void OnAudioRendererFlushDone();
   void FlushVideoRenderer();
   void OnVideoRendererFlushDone();
 
-  void RestartAudioRenderer(base::TimeDelta time);
-  void RestartVideoRenderer(base::TimeDelta time);
+  // Restart audio/video renderer playback after a media track switch or after a
+  // media track has been disabled and re-enabled. The |stream| parameter
+  // specifies which stream needs to be restarted. If it's the same as the most
+  // recently playing stream of that type, then the renderer is only restarted.
+  // But if it differs from the most recent stream, then the renderer is
+  // completely reinitialized, i.e. the corresponding DecoderStream is recreated
+  // and decoder is reinitialized too.
+  // The |time| parameter specifies the position on the media timeline where the
+  // playback needs to be restarted. It is necessary for demuxers with
+  // independent streams (e.g. MSE / ChunkDemuxer) to synchronize data reading
+  // between those streams.
+  void RestartAudioRenderer(DemuxerStream* stream, base::TimeDelta time);
+  void RestartVideoRenderer(DemuxerStream* stream, base::TimeDelta time);
+
+  // These callbacks are invoked when the corresponding renderer has been
+  // reinitialized. If the |status| indicates success, then playback of the
+  // |stream| should be resumed from media position specified by |time|.
+  void OnAudioRendererReinitCompleted(DemuxerStream* stream,

[xhwang, 2017/03/27 19:13:53]

nit: OnAudioRendererReinitialized, or OnAudioRendererReinitializeDone to be
consistent with line 99

[servolk, 2017/03/27 22:34:13]

Done.

+                                      base::TimeDelta time,
+                                      PipelineStatus status);
+  void OnVideoRendererReinitCompleted(DemuxerStream* stream,
+                                      base::TimeDelta time,
+                                      PipelineStatus status);
 
   // Callback executed by filters to update statistics.
   void OnStatisticsUpdate(const PipelineStatistics& stats);
 
   // Collection of callback methods and helpers for tracking changes in
   // buffering state and transition from paused/underflow states and playing
   // states.
   //
   // While in the kPlaying state:
   //   - A waiting to non-waiting transition indicates preroll has completed
@@ skipping 38 matching lines @@
 
   // Temporary callback used for Initialize() and Flush().
   PipelineStatusCB init_cb_;
   base::Closure flush_cb_;
 
   std::unique_ptr<RendererClientInternal> audio_renderer_client_;
   std::unique_ptr<RendererClientInternal> video_renderer_client_;
   std::unique_ptr<AudioRenderer> audio_renderer_;
   std::unique_ptr<VideoRenderer> video_renderer_;
 
+  DemuxerStream* current_audio_stream_;
+  DemuxerStream* current_video_stream_;
+
   // Renderer-provided time source used to control playback.
   TimeSource* time_source_;
   std::unique_ptr<WallClockTimeSource> wall_clock_time_source_;
   bool time_ticking_;
   double playback_rate_;
 
   // The time to start playback from after starting/seeking has completed.
   base::TimeDelta start_time_;
 
   BufferingState audio_buffering_state_;
@@ skipping 25 matching lines @@
 
   base::WeakPtr<RendererImpl> weak_this_;
   base::WeakPtrFactory<RendererImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RendererImpl);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_RENDERERS_RENDERER_IMPL_H_