Implement disabling and enabling media tracks

media/renderers/renderer_impl.cc

 // 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.
 
 #include "media/renderers/renderer_impl.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/callback.h"
@@ skipping 183 matching lines @@
   }
 
   time_source_->SetMediaTime(time);
 
   if (audio_renderer_)
     audio_renderer_->StartPlaying();
   if (video_renderer_)
     video_renderer_->StartPlayingFrom(time);
 }
 
+void RendererImpl::RestartStreamPlayback(DemuxerStream* stream,
+                                         base::TimeDelta time) {
+  DVLOG(1) << __FUNCTION__ << " stream=" << stream
+           << " time=" << time.InSecondsF();
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  if (stream->type() == DemuxerStream::VIDEO) {
+    DCHECK(video_renderer_);
+    DCHECK(video_ended_);
+    video_ended_ = false;
+    restarting_video_ = true;
+    video_renderer_->Flush(base::Bind(
+        &RendererImpl::OnVideoRendererFlushDone_ForRestart, weak_this_, time));
+  } else if (stream->type() == DemuxerStream::AUDIO) {
+    DCHECK(audio_renderer_);
+    DCHECK(time_source_);
+    DCHECK(audio_ended_);
+    audio_ended_ = false;
+    restarting_audio_ = true;
+    // We need to stop ticking (transition into paused state) before calling
+    // Flush, since after Flush we'll need to restart playback by invoking
+    // StartPlaying that dchecks we are not in playing state.

[wolenetz, 2016/05/27 20:49:42]

nit: we usually don't refer to implementation detail ("that dchecks"), rather
something like "that requires that"

[servolk, 2016/06/01 17:36:16]

Done.

+    time_ticking_ = false;
+    time_source_->StopTicking();
+    audio_renderer_->Flush(base::Bind(
+        &RendererImpl::OnAudioRendererFlushDone_ForRestart, weak_this_, time));
+  }
+}
+
+void RendererImpl::OnVideoRendererFlushDone_ForRestart(base::TimeDelta time) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  if (state_ == STATE_PLAYING) {
+    DCHECK(video_renderer_);
+    // TODO(servolk): VideoRenderer should ensure that Flush callback is called
+    // outside of its internal lock, to allow calling renderer methods directly.
+    task_runner_->PostTask(
+        FROM_HERE, base::Bind(&VideoRenderer::StartPlayingFrom,
+                              base::Unretained(video_renderer_.get()), time));
+  }
+}
+
+void RendererImpl::OnAudioRendererFlushDone_ForRestart(base::TimeDelta time) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  if (state_ == STATE_PLAYING) {
+    DCHECK(time_source_);
+    DCHECK(audio_renderer_);
+    audio_renderer_->StartPlaying();
+  }
+}
+
 void RendererImpl::SetPlaybackRate(double playback_rate) {
   DVLOG(1) << __FUNCTION__ << "(" << playback_rate << ")";
   DCHECK(task_runner_->BelongsToCurrentThread());
 
   // Playback rate changes are only carried out while playing.
   if (state_ != STATE_PLAYING)
     return;
 
   time_source_->SetPlaybackRate(playback_rate);
 
@@ skipping 281 matching lines @@
                                         ? &audio_buffering_state_
                                         : &video_buffering_state_;
 
   DVLOG(1) << __FUNCTION__ << "(" << *buffering_state << ", "
            << new_buffering_state << ") "
            << (type == DemuxerStream::AUDIO ? "audio" : "video");
   DCHECK(task_runner_->BelongsToCurrentThread());
 
   bool was_waiting_for_enough_data = WaitingForEnoughData();
 
+  // When restarting video stream playback we want to ignore the
+  // BUFFERING_HAVE_NOTHING notification so that audio keeps playing while
+  // video decoder is catching up.
+  if (type == DemuxerStream::VIDEO && restarting_video_) {
+    if (new_buffering_state == BUFFERING_HAVE_NOTHING) {
+      DVLOG(1) << __FUNCTION__ << " Ignoring BUFFERING_HAVE_NOTHING for video "
+                                  "stream which is being restarted.";
+    } else if (new_buffering_state == BUFFERING_HAVE_ENOUGH) {
+      DVLOG(1)
+          << __FUNCTION__
+          << " Got BUFFERING_HAVE_ENOUGH for video stream, resuming playback.";
+      restarting_video_ = false;
+      if (playback_rate_ > 0)
+        video_renderer_->OnTimeStateChanged(true);
+    }
+    return;
+  }
+
+  if (type == DemuxerStream::AUDIO && restarting_audio_) {
+    if (new_buffering_state == BUFFERING_HAVE_NOTHING) {
+      DVLOG(1) << __FUNCTION__ << " Ignoring BUFFERING_HAVE_NOTHING for "
+               << (type == DemuxerStream::AUDIO ? "audio" : "video")
+               << " stream";
+    } else if (new_buffering_state == BUFFERING_HAVE_ENOUGH) {
+      DVLOG(1) << __FUNCTION__ << " Got BUFFERING_HAVE_ENOUGH for "
+               << (type == DemuxerStream::AUDIO ? "audio" : "video")
+               << " stream";
+
+      restarting_audio_ = false;
+
+      // Now that we have decoded enough audio, pause and unpause playback
+      // momentarily to ensure video renderer is synchronised with audio.
+      double curr_playback_rate = playback_rate_;
+      SetPlaybackRate(0);
+      SetPlaybackRate(curr_playback_rate);
+
+      time_source_->StartTicking();
+    }
+    return;
+  }
+
   // When audio is present and has enough data, defer video underflow callbacks
   // for some time to avoid unnecessary glitches in audio; see
   // http://crbug.com/144683#c53.
   if (audio_renderer_ && type == DemuxerStream::VIDEO &&
       state_ == STATE_PLAYING) {
     if (video_buffering_state_ == BUFFERING_HAVE_ENOUGH &&
         audio_buffering_state_ == BUFFERING_HAVE_ENOUGH &&
         new_buffering_state == BUFFERING_HAVE_NOTHING &&
         deferred_underflow_cb_.IsCancelled()) {
       deferred_underflow_cb_.Reset(
@@ skipping 90 matching lines @@
   DCHECK(!time_ticking_);
   DCHECK(!WaitingForEnoughData());
 
   time_ticking_ = true;
   time_source_->StartTicking();
   if (playback_rate_ > 0 && video_renderer_)
     video_renderer_->OnTimeStateChanged(true);
 }
 
 void RendererImpl::OnRendererEnded(DemuxerStream::Type type) {
-  DVLOG(1) << __FUNCTION__;
+  DVLOG(1) << __FUNCTION__
+           << (type == DemuxerStream::AUDIO ? " audio" : " video");
   DCHECK(task_runner_->BelongsToCurrentThread());
   DCHECK((type == DemuxerStream::AUDIO) || (type == DemuxerStream::VIDEO));
 
   if (state_ != STATE_PLAYING)
     return;
 
   if (type == DemuxerStream::AUDIO) {
     DCHECK(!audio_ended_);
     audio_ended_ = true;
   } else {
@@ skipping 65 matching lines @@
   DCHECK(task_runner_->BelongsToCurrentThread());
   client_->OnVideoNaturalSizeChange(size);
 }
 
 void RendererImpl::OnVideoOpacityChange(bool opaque) {
   DCHECK(task_runner_->BelongsToCurrentThread());
   client_->OnVideoOpacityChange(opaque);
 }
 
 }  // namespace media