Introduce audio/video BufferingState to Pipeline.

media/base/pipeline.cc

 // 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.
 
 #include "media/base/pipeline.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/callback.h"
@@ skipping 30 matching lines @@
       did_loading_progress_(false),
       volume_(1.0f),
       playback_rate_(0.0f),
       clock_(new Clock(&default_tick_clock_)),
       waiting_for_clock_update_(false),
       status_(PIPELINE_OK),
       state_(kCreated),
       audio_ended_(false),
       video_ended_(false),
       text_ended_(false),
+      audio_buffering_state_(BUFFERING_HAVE_NOTHING),
+      video_buffering_state_(BUFFERING_HAVE_NOTHING),
       demuxer_(NULL),
       creation_time_(default_tick_clock_.NowTicks()) {
   media_log_->AddEvent(media_log_->CreatePipelineStateChangedEvent(kCreated));
   media_log_->AddEvent(
       media_log_->CreateEvent(MediaLogEvent::PIPELINE_CREATED));
 }
 
 Pipeline::~Pipeline() {
   DCHECK(thread_checker_.CalledOnValidThread())
       << "Pipeline must be destroyed on same thread that created it";
@@ skipping 120 matching lines @@
 
 void Pipeline::SetClockForTesting(Clock* clock) {
   clock_.reset(clock);
 }
 
 void Pipeline::SetErrorForTesting(PipelineStatus status) {
   SetError(status);
 }
 
 void Pipeline::SetState(State next_state) {
-  if (state_ != kStarted && next_state == kStarted &&
+  if (state_ != kPlaying && next_state == kPlaying &&
       !creation_time_.is_null()) {
     UMA_HISTOGRAM_TIMES("Media.TimeToPipelineStarted",
                         default_tick_clock_.NowTicks() - creation_time_);
     creation_time_ = base::TimeTicks();
   }
 
   DVLOG(2) << GetStateString(state_) << " -> " << GetStateString(next_state);
 
   state_ = next_state;
   media_log_->AddEvent(media_log_->CreatePipelineStateChangedEvent(next_state));
 }
 
 #define RETURN_STRING(state) case state: return #state;
 
 const char* Pipeline::GetStateString(State state) {
   switch (state) {
     RETURN_STRING(kCreated);
     RETURN_STRING(kInitDemuxer);
     RETURN_STRING(kInitAudioRenderer);
     RETURN_STRING(kInitVideoRenderer);
     RETURN_STRING(kInitPrerolling);
     RETURN_STRING(kSeeking);
-    RETURN_STRING(kStarting);
-    RETURN_STRING(kStarted);
+    RETURN_STRING(kPlaying);
     RETURN_STRING(kStopping);
     RETURN_STRING(kStopped);
   }
   NOTREACHED();
   return "INVALID";
 }
 
 #undef RETURN_STRING
 
 Pipeline::State Pipeline::GetNextState() const {
@@ skipping 16 matching lines @@
 
     case kInitAudioRenderer:
       if (demuxer_->GetStream(DemuxerStream::VIDEO))
         return kInitVideoRenderer;
       return kInitPrerolling;
 
     case kInitVideoRenderer:
       return kInitPrerolling;
 
     case kInitPrerolling:
-      return kStarting;
+      return kPlaying;
 
     case kSeeking:
-      return kStarting;
+      return kPlaying;
 
-    case kStarting:
-      return kStarted;
-
-    case kStarted:
+    case kPlaying:
     case kStopping:
     case kStopped:
       break;
   }
   NOTREACHED() << "State has no transition: " << state_;
   return state_;
 }
 
 void Pipeline::OnDemuxerError(PipelineStatus error) {
   SetError(error);
@@ skipping 86 matching lines @@
   // the previous operation.
   status_ = (status_ != PIPELINE_OK ? status_ : status);
 
   if (status_ != PIPELINE_OK) {
     ErrorChangedTask(status_);
     return;
   }
 
   // Guard against accidentally clearing |pending_callbacks_| for states that
   // use it as well as states that should not be using it.
-  //
-  // TODO(scherkus): Make every state transition use |pending_callbacks_|.
   DCHECK_EQ(pending_callbacks_.get() != NULL,
-            (state_ == kInitPrerolling || state_ == kStarting ||
-             state_ == kSeeking));
+            (state_ == kInitPrerolling || state_ == kSeeking));
+
   pending_callbacks_.reset();
 
   PipelineStatusCB done_cb = base::Bind(
       &Pipeline::OnStateTransition, base::Unretained(this));
 
   // Switch states, performing any entrance actions for the new state as well.
   SetState(GetNextState());
   switch (state_) {
     case kInitDemuxer:
       return InitializeDemuxer(done_cb);
@@ skipping 23 matching lines @@
         metadata.has_video = video_renderer_;
         metadata.timeline_offset = demuxer_->GetTimelineOffset();
         DemuxerStream* stream = demuxer_->GetStream(DemuxerStream::VIDEO);
         if (stream)
           metadata.natural_size = stream->video_decoder_config().natural_size();
         metadata_cb_.Run(metadata);
       }
 
       return DoInitialPreroll(done_cb);
 
-    case kStarting:
-      return DoPlay(done_cb);
+    case kPlaying:
+      PlaybackRateChangedTask(GetPlaybackRate());
+      VolumeChangedTask(GetVolume());
 
-    case kStarted:
-      {
-        base::AutoLock l(lock_);
-        // We use audio stream to update the clock. So if there is such a
-        // stream, we pause the clock until we receive a valid timestamp.
-        waiting_for_clock_update_ = true;
-        if (!audio_renderer_) {
-          clock_->SetMaxTime(clock_->Duration());
-          StartClockIfWaitingForTimeUpdate_Locked();
-        }
-      }
-
-      DCHECK(!seek_cb_.is_null());
-      DCHECK_EQ(status_, PIPELINE_OK);
-
-      // Fire canplaythrough immediately after playback begins because of
-      // crbug.com/106480.
-      // TODO(vrk): set ready state to HaveFutureData when bug above is fixed.
-      preroll_completed_cb_.Run();
-      return base::ResetAndReturn(&seek_cb_).Run(PIPELINE_OK);
+      // We enter this state from either kInitPrerolling or kSeeking. As of now
+      // both those states call Preroll(), which means by time we enter this
+      // state we've already buffered enough data. Forcefully update the
+      // buffering state, which start the clock and renderers and transition
+      // into kPlaying state.
+      //
+      // TODO(scherkus): Remove after renderers are taught to fire buffering
+      // state callbacks http://crbug.com/144683
+      DCHECK(WaitingForEnoughData());
+      if (audio_renderer_)
+        AudioBufferingStateChanged(BUFFERING_HAVE_ENOUGH);
+      if (video_renderer_)
+        VideoBufferingStateChanged(BUFFERING_HAVE_ENOUGH);
+      return;
 
     case kStopping:
     case kStopped:
     case kCreated:
     case kSeeking:
       NOTREACHED() << "State has no transition: " << state_;
       return;
   }
 }
 
@@ skipping 14 matching lines @@
   if (audio_renderer_) {
     bound_fns.Push(base::Bind(
         &AudioRenderer::Preroll, base::Unretained(audio_renderer_.get()),
         seek_timestamp));
   }
 
   if (video_renderer_) {
     bound_fns.Push(base::Bind(
         &VideoRenderer::Preroll, base::Unretained(video_renderer_.get()),
         seek_timestamp));
+
+    // TODO(scherkus): Remove after VideoRenderer is taught to fire buffering
+    // state callbacks http://crbug.com/144683
+    bound_fns.Push(base::Bind(&VideoRenderer::Play,
+                              base::Unretained(video_renderer_.get())));
+  }
+
+  if (text_renderer_) {
+    bound_fns.Push(base::Bind(
+        &TextRenderer::Play, base::Unretained(text_renderer_.get())));
   }
 
   pending_callbacks_ = SerialRunner::Run(bound_fns, done_cb);
 }
 
 void Pipeline::DoSeek(
     base::TimeDelta seek_timestamp,
     const PipelineStatusCB& done_cb) {
   DCHECK(task_runner_->BelongsToCurrentThread());
   DCHECK(!pending_callbacks_.get());
   SerialRunner::Queue bound_fns;
 
   // Pause.
   if (audio_renderer_) {
     bound_fns.Push(base::Bind(
         &AudioRenderer::Pause, base::Unretained(audio_renderer_.get())));
   }
   if (text_renderer_) {
     bound_fns.Push(base::Bind(
         &TextRenderer::Pause, base::Unretained(text_renderer_.get())));
   }
 
   // Flush.
   if (audio_renderer_) {
     bound_fns.Push(base::Bind(
         &AudioRenderer::Flush, base::Unretained(audio_renderer_.get())));
+
+    // TODO(scherkus): Remove after AudioRenderer is taught to fire buffering
+    // state callbacks http://crbug.com/144683
+    bound_fns.Push(base::Bind(&Pipeline::AudioBufferingStateChanged,
+                              base::Unretained(this),
+                              BUFFERING_HAVE_NOTHING));
   }
   if (video_renderer_) {
     bound_fns.Push(base::Bind(
         &VideoRenderer::Flush, base::Unretained(video_renderer_.get())));
+
+    // TODO(scherkus): Remove after VideoRenderer is taught to fire buffering
+    // state callbacks http://crbug.com/144683
+    bound_fns.Push(base::Bind(&Pipeline::VideoBufferingStateChanged,
+                              base::Unretained(this),
+                              BUFFERING_HAVE_NOTHING));
   }
   if (text_renderer_) {
     bound_fns.Push(base::Bind(
         &TextRenderer::Flush, base::Unretained(text_renderer_.get())));
   }
 
   // Seek demuxer.
   bound_fns.Push(base::Bind(
       &Demuxer::Seek, base::Unretained(demuxer_), seek_timestamp));
 
   // Preroll renderers.
   if (audio_renderer_) {
     bound_fns.Push(base::Bind(
         &AudioRenderer::Preroll, base::Unretained(audio_renderer_.get()),
         seek_timestamp));
   }
 
   if (video_renderer_) {
     bound_fns.Push(base::Bind(
         &VideoRenderer::Preroll, base::Unretained(video_renderer_.get()),
         seek_timestamp));
-  }
 
-  pending_callbacks_ = SerialRunner::Run(bound_fns, done_cb);
-}
-
-void Pipeline::DoPlay(const PipelineStatusCB& done_cb) {
-  DCHECK(task_runner_->BelongsToCurrentThread());
-  DCHECK(!pending_callbacks_.get());
-  SerialRunner::Queue bound_fns;
-
-  PlaybackRateChangedTask(GetPlaybackRate());
-  VolumeChangedTask(GetVolume());
-
-  if (audio_renderer_) {
-    bound_fns.Push(base::Bind(
-        &AudioRenderer::Play, base::Unretained(audio_renderer_.get())));
-  }
-
-  if (video_renderer_) {
-    bound_fns.Push(base::Bind(
-        &VideoRenderer::Play, base::Unretained(video_renderer_.get())));
+    // TODO(scherkus): Remove after renderers are taught to fire buffering
+    // state callbacks http://crbug.com/144683
+    bound_fns.Push(base::Bind(&VideoRenderer::Play,
+                              base::Unretained(video_renderer_.get())));
   }
 
   if (text_renderer_) {
     bound_fns.Push(base::Bind(
         &TextRenderer::Play, base::Unretained(text_renderer_.get())));
   }
 
   pending_callbacks_ = SerialRunner::Run(bound_fns, done_cb);
 }
 
@@ skipping 145 matching lines @@
   pending_callbacks_.reset();
   status_ = error;
 
   DoStop(base::Bind(&Pipeline::OnStopCompleted, base::Unretained(this)));
 }
 
 void Pipeline::PlaybackRateChangedTask(float playback_rate) {
   DCHECK(task_runner_->BelongsToCurrentThread());
 
   // Playback rate changes are only carried out while playing.
-  if (state_ != kStarting && state_ != kStarted)
+  if (state_ != kPlaying)
     return;
 
   {
     base::AutoLock auto_lock(lock_);
     clock_->SetPlaybackRate(playback_rate);
   }
 
   if (audio_renderer_)
     audio_renderer_->SetPlaybackRate(playback_rate_);
   if (video_renderer_)
     video_renderer_->SetPlaybackRate(playback_rate_);
 }
 
 void Pipeline::VolumeChangedTask(float volume) {
   DCHECK(task_runner_->BelongsToCurrentThread());
 
   // Volume changes are only carried out while playing.
-  if (state_ != kStarting && state_ != kStarted)
+  if (state_ != kPlaying)
     return;
 
   if (audio_renderer_)
     audio_renderer_->SetVolume(volume);
 }
 
 void Pipeline::SeekTask(TimeDelta time, const PipelineStatusCB& seek_cb) {
   DCHECK(task_runner_->BelongsToCurrentThread());
   DCHECK(stop_cb_.is_null());
 
   // Suppress seeking if we're not fully started.
-  if (state_ != kStarted) {
+  if (state_ != kPlaying) {
     DCHECK(state_ == kStopping || state_ == kStopped)
         << "Receive extra seek in unexpected state: " << state_;
 
     // TODO(scherkus): should we run the callback?  I'm tempted to say the API
     // will only execute the first Seek() request.
     DVLOG(1) << "Media pipeline has not started, ignoring seek to "
              << time.InMicroseconds() << " (current state: " << state_ << ")";
     return;
   }
 
@@ skipping 13 matching lines @@
       clock_->Pause();
     clock_->SetTime(seek_timestamp, seek_timestamp);
   }
   DoSeek(seek_timestamp, base::Bind(
       &Pipeline::OnStateTransition, base::Unretained(this)));
 }
 
 void Pipeline::DoAudioRendererEnded() {
   DCHECK(task_runner_->BelongsToCurrentThread());
 
-  if (state_ != kStarted)
+  if (state_ != kPlaying)
     return;
 
   DCHECK(!audio_ended_);
   audio_ended_ = true;
 
   // Start clock since there is no more audio to trigger clock updates.
   {
     base::AutoLock auto_lock(lock_);
     clock_->SetMaxTime(clock_->Duration());
     StartClockIfWaitingForTimeUpdate_Locked();
   }
 
   RunEndedCallbackIfNeeded();
 }
 
 void Pipeline::DoVideoRendererEnded() {
   DCHECK(task_runner_->BelongsToCurrentThread());
 
-  if (state_ != kStarted)
+  if (state_ != kPlaying)
     return;
 
   DCHECK(!video_ended_);
   video_ended_ = true;
 
   RunEndedCallbackIfNeeded();
 }
 
 void Pipeline::DoTextRendererEnded() {
   DCHECK(task_runner_->BelongsToCurrentThread());
 
-  if (state_ != kStarted)
+  if (state_ != kPlaying)
     return;
 
   DCHECK(!text_ended_);
   text_ended_ = true;
 
   RunEndedCallbackIfNeeded();
 }
 
 void Pipeline::RunEndedCallbackIfNeeded() {
   DCHECK(task_runner_->BelongsToCurrentThread());
@@ skipping 66 matching lines @@
       base::Bind(&Pipeline::GetMediaDuration, base::Unretained(this)));
 }
 
 void Pipeline::OnAudioUnderflow() {
   if (!task_runner_->BelongsToCurrentThread()) {
     task_runner_->PostTask(FROM_HERE, base::Bind(
         &Pipeline::OnAudioUnderflow, base::Unretained(this)));
     return;
   }
 
-  if (state_ != kStarted)
+  if (state_ != kPlaying)
     return;
 
   if (audio_renderer_)
     audio_renderer_->ResumeAfterUnderflow();
 }
 
+void Pipeline::AudioBufferingStateChanged(BufferingState buffering_state) {

[acolwell GONE FROM CHROMIUM, 2014/05/12 13:46:54]

nit: You could avoid duplicate code below if you bound the xxx_buffering_state_
to the callback so it could be passed in as a parameter here.

[scherkus (not reviewing), 2014/05/12 15:22:03]

Done.

+  DCHECK(task_runner_->BelongsToCurrentThread());
+  bool was_waiting_for_enough_data = WaitingForEnoughData();
+  audio_buffering_state_ = buffering_state;
+
+  // Audio renderer underflowed.
+  if (!was_waiting_for_enough_data && WaitingForEnoughData()) {
+    StartWaitingForEnoughData();
+    return;
+  }
+
+  // Audio renderer prerolled.
+  if (was_waiting_for_enough_data && !WaitingForEnoughData()) {
+    StartPlayback();
+    return;
+  }
+}
+
+void Pipeline::VideoBufferingStateChanged(BufferingState buffering_state) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  bool was_waiting_for_enough_data = WaitingForEnoughData();
+  video_buffering_state_ = buffering_state;
+
+  // Video renderer underflowed.
+  if (!was_waiting_for_enough_data && WaitingForEnoughData()) {
+    StartWaitingForEnoughData();
+    return;
+  }
+
+  // Video renderer prerolled.
+  if (was_waiting_for_enough_data && !WaitingForEnoughData()) {
+    StartPlayback();
+    return;
+  }
+}
+
+bool Pipeline::WaitingForEnoughData() const {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  if (state_ != kPlaying)
+    return false;
+  if (audio_renderer_ && audio_buffering_state_ != BUFFERING_HAVE_ENOUGH)
+    return true;
+  if (video_renderer_ && video_buffering_state_ != BUFFERING_HAVE_ENOUGH)
+    return true;
+  return false;
+}
+
+void Pipeline::StartWaitingForEnoughData() {
+  DCHECK_EQ(state_, kPlaying);
+  DCHECK(WaitingForEnoughData());
+
+  if (audio_renderer_)
+    audio_renderer_->Pause();
+
+  base::AutoLock auto_lock(lock_);
+  clock_->Pause();
+}
+
+void Pipeline::StartPlayback() {
+  DCHECK_EQ(state_, kPlaying);
+  DCHECK(!WaitingForEnoughData());
+
+  if (audio_renderer_) {
+    audio_renderer_->Play();
+
+    base::AutoLock auto_lock(lock_);
+    // We use video stream to update the clock. So if there is such a

[acolwell GONE FROM CHROMIUM, 2014/05/12 13:46:54]

nit: s/video/audio?

[scherkus (not reviewing), 2014/05/12 15:22:03]

Done.

+    // stream, we pause the clock until we receive a valid timestamp.
+    waiting_for_clock_update_ = true;
+  } else {
+    base::AutoLock auto_lock(lock_);
+    clock_->SetMaxTime(clock_->Duration());
+    clock_->Play();
+  }
+
+  preroll_completed_cb_.Run();
+  if (!seek_cb_.is_null())
+    base::ResetAndReturn(&seek_cb_).Run(PIPELINE_OK);
+}
+
 void Pipeline::StartClockIfWaitingForTimeUpdate_Locked() {
   lock_.AssertAcquired();
   if (!waiting_for_clock_update_)
     return;
 
   waiting_for_clock_update_ = false;
   clock_->Play();
 }
 
 }  // namespace media