MediaCodecPlayer (stage 1 - play/pause only)

media/base/android/media_codec_player.h

Index: media/base/android/media_codec_player.h
diff --git a/media/base/android/media_codec_player.h b/media/base/android/media_codec_player.h
index 518adbbbd8b17874e398fde3d9481762db02b4d9..a3c93bbf23289dea469ffbf975922be0053577b8 100644
--- a/media/base/android/media_codec_player.h
+++ b/media/base/android/media_codec_player.h
@@ -9,35 +9,166 @@
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/thread.h"
+#include "base/time/default_tick_clock.h"
 #include "media/base/android/demuxer_android.h"
 #include "media/base/android/media_player_android.h"
+#include "media/base/demuxer_stream.h"
 #include "media/base/media_export.h"
+#include "media/base/time_delta_interpolator.h"
+#include "ui/gfx/geometry/size.h"
 #include "ui/gl/android/scoped_java_surface.h"
 
+// The MediaCodecPlayer class implements the media player by using Android's
+// MediaCodec. It differs from MediaSourcePlayer in that it removes most
+// processing away from the UI thread: it uses a dedicated Media thread to
+// receive the data and to handle the commands.
+
+// The player works as a state machine. Here are relationships between states:

[liberato (no reviews please), 2015/06/23 14:58:59]

this comment would be clearer with a little color and animation.  and audio
narration.  in 7.1.  text-only comments in media code don't set the right
example.

[Tima Vaisburd, 2015/06/24 02:31:07]

I take this as a subtle hint that these diagrams are better be removed. Well, it
is definitely easier than was adding them. Removed most of it.

[liberato (no reviews please), 2015/06/24 06:17:56]

no!

they're great.  please git reflog them back!  i just felt the need to comment on
them, kind of like commenting on mt. rushmore -- you just have to say
_something_.

i can see them being a maintenance problem (nobody is going to keep them up to
date), but i'd rather deal with that if it actually arises.  i'm sure there are
more compact ways to portray it, but that's a problem we should be glad to have
more often.

sorry about the confusion.

[wolenetz, 2015/06/25 22:31:39]

aside: I use "aside:" when I see something I like and want to mention that or I
have a non-l*tm-blocking question or other non-nit that I'd like to mention...
:)

+//
+//   [ Paused ] ------------------------                         (Any state)
+//        |                             |                             |
+//        |                             v                             v
+//        | <------------------[ WaitingForConfig ]               [ Error ]
+//        |
+//        |
+//        | <----------------------------------------------
+//        v                                                |
+//   [ Prefetching ] -------------------                   |
+//        |                             |                  |
+//        |                             v                  |
+//        | <-----------------[ WaitingForSurface ]        |
+//        v                                                |
+//   [ Playing ]                                           |
+//        |                                                |
+//        |                                                |
+//        v                                                |
+//   [ Stopping ] --------------------------------> [ WaitingForSeek ]
+//
+//
+
+/*

[watk, 2015/06/24 22:36:07]

Should this block comment be turned into // line comments for consistency with
above?

[Tima Vaisburd, 2015/06/25 01:23:36]

Done.

+   Events and actions for pause/resume workflow.
+   ---------------------------------------------
+
+                                            Start, no config:
+       ------------------------> [ Paused ] -----------------> [   Waiting   ]
+       |  StopDone:                                            [ for configs ]
+       |                            ^  |                              /
+       |                            |  |                             /
+       |                    Pause:  |  | Start w/config:            /
+       |                            |  |    dec.Prefetch           /
+       |                            |  |                          /
+       |                            |  |                         /
+       |                            |  |                        /
+       |                            |  |                       / DemuxerConfigs:
+       |                            |  |                      /   dec.Prefetch
+       |                            |  |                     /
+       |                            |  |                    /
+       |                            |  v                   /
+       |                                                  /
+       |   ------------------> [ Prefetching ]  <--------/      [   Waiting   ]
+       |   |                   [             ] -------------->  [ for surface ]
+       |   |                          |         PrefetchDone,         /
+       |   |                          |          no surface:         /
+       |   |                          |                             /
+       |   |                          |                            /
+       |   | StopDone w/              |                           /
+       |   | pending start:           | PrefetchDone:            /
+       |   |    dec.Prefetch          |   dec.Start             /
+       |   |                          |                        / SetSurface:
+       |   |                          |                       /     dec.Start
+       |   |                          |                      /
+       |   |                          v                     /
+       |   |                                               /
+       |   |                     [ Playing ]   <----------/
+       |   |
+       |   |                          |
+       |   |                          |
+       |   |                          | Pause: dec.RequestToStop
+       |   |                          |
+       |   |                          |
+       |   |                          v
+       |   |
+       ------------------------- [ Stopping ]
+
+
+    Events and actions for seek workflow.
+    -------------------------------------
+
+                    Seek:                   --       --
+                        demuxer.RequestSeek |         |
+   [   Paused    ] -----------------------> |         |
+   [             ] <----------------------- |         |--
+                       SeekDone:            |         |  |
+                                            |         |  |
+                                            |         |  |
+                                            |         |  |
+                                            |         |  | Start:
+                     Seek:                  |         |  |   SetPendingStart
+                       dec.Stop             |         |  |
+                       SetPendingSeek       |         |  |
+                       demuxer.RequestSeek  |         |  |
+   [ Prefetching ] -----------------------> |         |  |
+   [             ] <----------------------  |         |  | Pause:
+         |          SeekDone                |         |  |   RemovePendingStart
+         |          w/pending start:        |         |  |
+         |            dec.Prefetch          | Waiting |  |
+         |                                  |   for   |  | Seek:
+         |                                  |   seek  |  |   SetPendingSeek
+         |                                  |         |  |
+         | PrefetchDone: dec.Start          |         |  |
+         |                                  |         |  | SeekDone
+         v                                  |         |  | w/pending seek:
+                                            |         |  |   demuxer.RequestSeek
+   [   Playing   ]                          |         |  |
+                                            |         |  |
+         |                                  |         |<-
+         | Seek: SetPendingStart            |         |
+         |       SetPendingSeek             |         |
+         |       dec.RequestToStop          |         |
+         |                                  |         |
+         |                                  |         |
+         v                                  |         |
+                                            |         |
+   [  Stopping   ] -----------------------> |         |
+                   StopDone                 --       --
+                   w/pending seek:
+                     demuxer.RequestSeek
+ */
+
 namespace media {
 
 class BrowserCdm;
+class MediaCodecAudioDecoder;
+class MediaCodecVideoDecoder;
 
 // Returns the task runner for the media thread
 MEDIA_EXPORT scoped_refptr<base::SingleThreadTaskRunner> GetMediaTaskRunner();
 
-
-// This class implements the media player using Android's MediaCodec.
-// It differs from MediaSourcePlayer in that it removes most
-// processing away from UI thread: it uses a dedicated Media thread
-// to receive the data and to handle commands.
 class MEDIA_EXPORT MediaCodecPlayer : public MediaPlayerAndroid,
                                       public DemuxerAndroidClient {
  public:
+  // Typedefs for the notification callbacks
+  typedef base::Callback<void(base::TimeDelta duration,
+                              const gfx::Size& video_size)>
+      MetadataChangedCallback;

[liberato (no reviews please), 2015/06/23 14:58:59]

nit: spacing looks weird.

[Tima Vaisburd, 2015/06/24 02:31:07]

Removed parameter names. 

+
+  typedef base::Callback<void(base::TimeDelta current_timestamp,
+                              base::TimeTicks current_ticks)>
+      TimeUpdateCallback;
+
   // Constructs a player with the given ID and demuxer. |manager| must outlive
   // the lifetime of this object.
   MediaCodecPlayer(int player_id,
-                   MediaPlayerManager* manager,
+                   base::WeakPtr<MediaPlayerManager> manager,
                    const RequestMediaResourcesCB& request_media_resources_cb,
                    scoped_ptr<DemuxerAndroid> demuxer,
                    const GURL& frame_url);
   ~MediaCodecPlayer() override;
 
+  // A helper method that performs the media thread part of initialization.
+  void Initialize();
+
   // MediaPlayerAndroid implementation.
   void DeleteOnCorrectThread() override;
   void SetVideoSurface(gfx::ScopedJavaSurface surface) override;
@@ -63,15 +194,122 @@ class MEDIA_EXPORT MediaCodecPlayer : public MediaPlayerAndroid,
   void OnDemuxerSeekDone(base::TimeDelta actual_browser_seek_time) override;
   void OnDemuxerDurationChanged(base::TimeDelta duration) override;
 
-  // Helper methods
-  void Initialize();
-  void DestroySelf();
+  base::WeakPtr<MediaCodecPlayer> weak_ptr() const { return weak_this_; }
+
+ protected:
+  // MediaPlayerAndroid implementation.
+  // This method caches the data and calls manager's OnMediaMetadataChanged().
+  void OnMediaMetadataChanged(base::TimeDelta duration,
+                              const gfx::Size& video_size) override;
+
+  // This method cached the current time and calls manager's OnTimeUpdate().
+  void OnTimeUpdate(base::TimeDelta current_timestamp,
+                    base::TimeTicks current_time_ticks) override;
 
  private:
+  // The state machine states.
+  enum PlayerState {
+    STATE_PAUSED,
+    STATE_WAITING_FOR_CONFIG,
+    STATE_PREFETCHING,
+    STATE_PLAYING,
+    STATE_STOPPING,
+    STATE_WAITING_FOR_SURFACE,
+    STATE_WAITING_FOR_SEEK,
+    STATE_ERROR,
+  };
+
+  // Cached values for the manager, accessed on the UI thread.
+  struct MediaMetadata {
+    base::TimeDelta duration;
+    gfx::Size video_size;
+    MediaMetadata() : duration(), video_size(0, 0) {}
+  };
+
+  // Callbacks from decoders
+  void RequestDemuxerData(DemuxerStream::Type stream_type);
+  void OnPrefetchDone();
+  void OnStarvation();
+  void OnStopDone();
+  void OnError();
+  void OnTimeIntervalUpdate(base::TimeDelta now_playing,
+                            base::TimeDelta last_buffered);
+
+  // Callbacks from video decoder
+  void OnVideoCodecCreated();
+  void OnVideoSizeChanged(const gfx::Size& size);
+
+  // Operations called from the state machine.
+  void SetState(PlayerState new_state);
+  void SetPendingSurface(gfx::ScopedJavaSurface surface);
+  bool HasPendingSurface();
+  void SetPendingStart(bool need_to_start);
+  bool HasPendingStart();
+  bool HasVideo();
+  bool HasAudio();
+  void SetDemuxerConfigs(const DemuxerConfigs& configs);
+  void StartPrefetchDecoders();
+  void StartPlaybackDecoders();
+  void StopDecoders();
+  void RequestToStopDecoders();
+  void ReleaseDecoderResources();
+
+  // Helper methods.
+  void CreateDecoders();
+  bool AudioFinished();
+  bool VideoFinished();
+  base::TimeDelta GetInterpolatedTime();
+
+  static const char* AsString(PlayerState state);
+
+  // Data.
+
   // Object for posting tasks on UI thread.
   scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner_;
 
+  // Major components: demuxer, audio and video decoders.
   scoped_ptr<DemuxerAndroid> demuxer_;
+  scoped_ptr<MediaCodecAudioDecoder> audio_decoder_;
+  scoped_ptr<MediaCodecVideoDecoder> video_decoder_;
+
+  // The state of the state machine.
+  PlayerState state_;
+
+  // Notification callbacks, they call MediaPlayerManager.
+  base::Closure request_resources_cb_;
+  TimeUpdateCallback time_update_cb_;
+  base::Closure completion_cb_;
+
+  // A callback that updates metadata cache and calls the manager.
+  MetadataChangedCallback metadata_changed_cb_;
+
+  // We call the base class' AttachListener() and DetachListener() methods on UI
+  // thread with these callbacks.
+  base::Closure attach_listener_cb_;
+  base::Closure detach_listener_cb_;
+
+  // Error callback might be posted internally
+  base::Closure error_cb_;
+
+  // Total duration reported by demuxer.
+  base::TimeDelta duration_;
+
+  // base::TickClock used by |interpolator_|.
+  base::DefaultTickClock default_tick_clock_;
+
+  // Tracks the most recent media time update and provides interpolated values
+  // as playback progresses.
+  TimeDeltaInterpolator interpolator_;
+
+  // Pending data to be picked up by the upcoming state.
+  gfx::ScopedJavaSurface pending_surface_;
+  bool pending_start_;
+
+  // Configuration data for the manager, accessed on the UI thread.
+  MediaMetadata metadata_cache_;
+
+  // Cached current time, accessed on UI thread.
+  base::TimeDelta current_time_cache_;
 
   base::WeakPtr<MediaCodecPlayer> weak_this_;
   // NOTE: Weak pointers must be invalidated before all other member variables.