Render inband text tracks in the media pipeline

media/base/pipeline.h

 // Copyright (c) 2012 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_BASE_PIPELINE_H_
 #define MEDIA_BASE_PIPELINE_H_
 
 #include <string>
 
 #include "base/gtest_prod_util.h"
@@ skipping 12 matching lines @@
 namespace base {
 class MessageLoopProxy;
 class TimeDelta;
 }
 
 namespace media {
 
 class Clock;
 class FilterCollection;
 class MediaLog;
+class TextRenderer;
 class VideoRenderer;
 
 // Pipeline runs the media pipeline.  Filters are created and called on the
 // message loop injected into this object. Pipeline works like a state
 // machine to perform asynchronous initialization, pausing, seeking and playing.
 //
 // Here's a state diagram that describes the lifetime of this object.
 //
 //   [ *Created ]                       [ Any State ]
 //         | Start()                         | Stop() / SetError()
@@ skipping 88 matching lines @@
   // returns true, it is expected that Stop() will be called before destroying
   // the pipeline.
   bool IsRunning() const;
 
   // Returns true if the media has audio.
   bool HasAudio() const;
 
   // Returns true if the media has video.
   bool HasVideo() const;
 
+  // Returns true if the media has text.
+  bool HasText() const;

[acolwell GONE FROM CHROMIUM, 2013/09/12 00:15:15]

nit: This only appears to be used by test code. Do we really need it?

[Matthew Heaney (Chromium), 2013/09/13 19:51:54]

I don't think so.  We can replace it with some alternative, if you like.

[Matthew Heaney (Chromium), 2013/09/20 23:53:54]

I finally removed it.

+
   // Gets the current playback rate of the pipeline.  When the pipeline is
   // started, the playback rate will be 0.0f.  A rate of 1.0f indicates
   // that the pipeline is rendering the media at the standard rate.  Valid
   // values for playback rate are >= 0.0f.
   float GetPlaybackRate() const;
 
   // Attempt to adjust the playback rate. Setting a playback rate of 0.0f pauses
   // all rendering of the media.  A rate of 1.0f indicates a normal playback
   // rate.  Values for the playback rate must be greater than or equal to 0.0f.
   //
@@ skipping 47 matching lines @@
   FRIEND_TEST_ALL_PREFIXES(PipelineTest, EndedCallback);
   FRIEND_TEST_ALL_PREFIXES(PipelineTest, AudioStreamShorterThanVideo);
   friend class MediaLog;
 
   // Pipeline states, as described above.
   enum State {
     kCreated,
     kInitDemuxer,
     kInitAudioRenderer,
     kInitVideoRenderer,
+    kInitTextRenderer,
     kInitPrerolling,
     kSeeking,
     kStarting,
     kStarted,
     kStopping,
     kStopped,
   };
 
   // Updates |state_|. All state transitions should use this call.
   void SetState(State next_state);
@@ skipping 19 matching lines @@
   //
   // Safe to call from any thread.
   void SetError(PipelineStatus error);
 
   // Callback executed when the natural size of the video has changed.
   void OnNaturalVideoSizeChanged(const gfx::Size& size);
 
   // Callbacks executed when a renderer has ended.
   void OnAudioRendererEnded();
   void OnVideoRendererEnded();
+  void OnTextRendererEnded();
 
   // Callback executed by filters to update statistics.
   void OnUpdateStatistics(const PipelineStatistics& stats);
 
   // Callback executed by audio renderer when it has been disabled.
   void OnAudioDisabled();
 
   // Callback executed by audio renderer to update clock time.
   void OnAudioTimeUpdate(base::TimeDelta time, base::TimeDelta max_time);
 
@@ skipping 19 matching lines @@
 
   // Carries out notifying filters that the playback rate has changed.
   void PlaybackRateChangedTask(float playback_rate);
 
   // Carries out notifying filters that the volume has changed.
   void VolumeChangedTask(float volume);
 
   // Carries out notifying filters that we are seeking to a new timestamp.
   void SeekTask(base::TimeDelta time, const PipelineStatusCB& seek_cb);
 
-  // Handles audio/video ended logic and running |ended_cb_|.
+  // Handles audio/video/text ended logic and running |ended_cb_|.
   void DoAudioRendererEnded();
   void DoVideoRendererEnded();
+  void DoTextRendererEnded();
   void RunEndedCallbackIfNeeded();
 
   // Carries out disabling the audio renderer.
   void AudioDisabledTask();
 
   // Kicks off initialization for each media object, executing |done_cb| with
   // the result when completed.
   void InitializeDemuxer(const PipelineStatusCB& done_cb);
   void InitializeAudioRenderer(const PipelineStatusCB& done_cb);
   void InitializeVideoRenderer(const PipelineStatusCB& done_cb);
+  void InitializeTextRenderer(const PipelineStatusCB& done_cb);
 
   // Kicks off destroying filters. Called by StopTask() and ErrorChangedTask().
   // When we start to tear down the pipeline, we will consider two cases:
   // 1. when pipeline has not been initialized, we will transit to stopping
   // state first.
   // 2. when pipeline has been initialized, we will first transit to pausing
   // => flushing => stopping => stopped state.
   // This will remove the race condition during stop between filters.
   void TearDownPipeline();
 
@@ skipping 76 matching lines @@
   // for an update of the clock greater than or equal to the elapsed time to
   // start the clock.
   bool waiting_for_clock_update_;
 
   // Status of the pipeline.  Initialized to PIPELINE_OK which indicates that
   // the pipeline is operating correctly. Any other value indicates that the
   // pipeline is stopped or is stopping.  Clients can call the Stop() method to
   // reset the pipeline state, and restore this to PIPELINE_OK.
   PipelineStatus status_;
 
-  // Whether the media contains rendered audio and video streams.
+  // Whether the media contains rendered audio, video, and text streams.
   // TODO(fischman,scherkus): replace these with checks for
   // {audio,video}_decoder_ once extraction of {Audio,Video}Decoder from the
   // Filter heirarchy is done.
   bool has_audio_;
   bool has_video_;
+  bool has_text_;
 
   // The following data members are only accessed by tasks posted to
   // |message_loop_|.
 
   // Member that tracks the current state.
   State state_;
 
-  // Whether we've received the audio/video ended events.
+  // Whether we've received the audio/video/text ended events.
   bool audio_ended_;
   bool video_ended_;
+  bool text_ended_;
 
   // Set to true in DisableAudioRendererTask().
   bool audio_disabled_;
 
   // Temporary callback used for Start() and Seek().
   PipelineStatusCB seek_cb_;
 
   // Temporary callback used for Stop().
   base::Closure stop_cb_;
 
   // Permanent callbacks passed in via Start().
   base::Closure ended_cb_;
   PipelineStatusCB error_cb_;
   BufferingStateCB buffering_state_cb_;
   base::Closure duration_change_cb_;
 
   // Contains the demuxer and renderers to use when initializing.
   scoped_ptr<FilterCollection> filter_collection_;
 
   // Holds the initialized demuxer. Used for seeking. Owned by client.
   Demuxer* demuxer_;
 
   // Holds the initialized renderers. Used for setting the volume,
   // playback rate, and determining when playback has finished.
   scoped_ptr<AudioRenderer> audio_renderer_;
   scoped_ptr<VideoRenderer> video_renderer_;
+  scoped_ptr<TextRenderer> text_renderer_;
 
   PipelineStatistics statistics_;
 
   // Time of pipeline creation; is non-zero only until the pipeline first
   // reaches "kStarted", at which point it is used & zeroed out.
   base::TimeTicks creation_time_;
 
   scoped_ptr<SerialRunner> pending_callbacks_;
 
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(Pipeline);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_PIPELINE_H_