Determine the audible state in MediaSourcePlayer

media/base/android/media_source_player.cc

Index: media/base/android/media_source_player.cc
diff --git a/media/base/android/media_source_player.cc b/media/base/android/media_source_player.cc
index 85ffd545d87877f787ca8d3a13fc55c1408460bd..155fd081d0af33f958f1cd5e42f7045802aad3e3 100644
--- a/media/base/android/media_source_player.cc
+++ b/media/base/android/media_source_player.cc
@@ -61,6 +61,7 @@ MediaSourcePlayer::MediaSourcePlayer(
                  weak_factory_.GetWeakPtr())));
   demuxer_->Initialize(this);
   interpolator_.SetUpperBound(base::TimeDelta());
+  audible_state_idle_period_ = base::TimeDelta::FromMilliseconds(1000);
   weak_this_ = weak_factory_.GetWeakPtr();
 }
 
@@ -194,6 +195,9 @@ void MediaSourcePlayer::Release() {
   playing_ = false;
 
   decoder_starvation_callback_.Cancel();
+  audible_audio_stopped_callback_.Cancel();
+
+  SetAudible(false);
   DetachListener();
 }
 
@@ -238,6 +242,7 @@ void MediaSourcePlayer::OnDemuxerConfigsAvailable(
     const DemuxerConfigs& configs) {
   DVLOG(1) << __FUNCTION__;
   DCHECK(!HasAudio() && !HasVideo());
+
   duration_ = configs.duration;
 
   audio_decoder_job_->SetDemuxerConfigs(configs);
@@ -399,6 +404,7 @@ void MediaSourcePlayer::ProcessPendingEvents() {
 
   if (IsEventPending(PREFETCH_REQUEST_EVENT_PENDING)) {
     DVLOG(1) << __FUNCTION__ << " : Handling PREFETCH_REQUEST_EVENT.";
+
     int count = (AudioFinished() ? 0 : 1) + (VideoFinished() ? 0 : 1);
 
     // It is possible that all streams have finished decode, yet starvation
@@ -574,6 +580,7 @@ void MediaSourcePlayer::DecodeMoreAudio() {
     case MediaDecoderJob::STATUS_SUCCESS:
       TRACE_EVENT_ASYNC_BEGIN0("media", "MediaSourcePlayer::DecodeMoreAudio",
                                audio_decoder_job_.get());
+      UpdateAudibleStatus();
       break;
     case MediaDecoderJob::STATUS_KEY_FRAME_REQUIRED:
       NOTREACHED();
@@ -586,6 +593,24 @@ void MediaSourcePlayer::DecodeMoreAudio() {
   }
 }
 
+void MediaSourcePlayer::SetAudibleStateIdlePeriod(base::TimeDelta duration) {
+  audible_state_idle_period_ = duration;
+}
+
+void MediaSourcePlayer::UpdateAudibleStatus() {

[qinmin, 2015/03/19 23:34:23]

I don't think we really need a timer for this. We can just wait for the decoder
callback and update the audible status. 
If we really want to be very accurate, we need to monitor the number of
remaining bytes in the AudioTrack object, rather than using a timer. 
For example, if the AudioDecoder is blocked on the AudioTrack while writing a
large chunk of data, the timer may expire and signal an idle state. However,
that is not really true since there are data in the AudioTrack

+  SetAudible(audio_decoder_job_->GetVolume() > 0);
+
+  audible_audio_stopped_callback_.Cancel();
+
+  audible_audio_stopped_callback_.Reset(
+      base::Bind(&MediaSourcePlayer::SetAudible, weak_this_, false));
+
+  DCHECK(audible_state_idle_period_ > base::TimeDelta());
+  base::MessageLoop::current()->PostDelayedTask(
+      FROM_HERE, audible_audio_stopped_callback_.callback(),
+      audible_state_idle_period_);
+}
+
 void MediaSourcePlayer::DecodeMoreVideo() {
   DVLOG(1) << __FUNCTION__;
   DCHECK(!video_decoder_job_->is_decoding());