Disable timer check for no data in AudioInputController for mirroring.

In very rare cases (i.e., hard to repro), the "no data" timer in AudioInputController discovers that over one second has elapsed between calls to OnData().  It interprets this as a failure of the platform to report an error or a device close event (see bug 79936).  However, for the audio mirroring use case, it's plausible that in poor-performing circumstances audio output can be delayed, which will then cause delays as it is looped-back into the mirrored input stream.

Example sequence of events leading to failure:

1. Mirroring input stream asks AudioConverter for more data.
2. AudioConverter blocks (up to 683 ms) waiting to pull in audio output data.
3. Audio output data is provided after 600 ms.
4. AudioConverter consumes the data, but it is not enough to fill the buffer.  So, it asks AudioConverter for more data.
5. Repeat steps 2 and 3.
6. By now, more than 1 second has elapsed since step 1, and the "no data" timer in AudioInputController error's-out the stream.
7. Sadness.

BUG=230972

Review URL: https://chromiumcodereview.appspot.com/14494002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@196379 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 36 insertions, 15 deletions

diff --git a/media/audio/audio_input_controller.cc b/media/audio/audio_input_controller.cc
index e8fc6e7..2e408db 100644
--- a/media/audio/audio_input_controller.cc
+++ b/media/audio/audio_input_controller.cc
@@ -10,6 +10,12 @@
 
 namespace {
 const int kMaxInputChannels = 2;
+
+// TODO(henrika): remove usage of timers and add support for proper
+// notification of when the input device is removed.  This was originally added
+// to resolve http://crbug.com/79936 for Windows platforms.  This then caused
+// breakage (very hard to repro bugs!) on other platforms: See
+// http://crbug.com/226327 and http://crbug.com/230972.
 const int kTimerResetIntervalSeconds = 1;
 #if defined(OS_IOS)
 // The first callback on iOS is received after the current background
@@ -19,9 +25,6 @@ const int kTimerInitialIntervalSeconds = 4;
 // We have received reports that the timer can be too trigger happy on some
 // Mac devices and the initial timer interval has therefore been increased
 // from 1 second to 5 seconds.
-// TODO(henrika): remove usage of timers and add support for proper
-// notification of when the input device is removed.
-// See http://crbug.com/226327 for details.
 const int kTimerInitialIntervalSeconds = 5;
 #endif  // defined(OS_IOS)
 }
@@ -123,10 +126,15 @@ scoped_refptr<AudioInputController> AudioInputController::CreateForStream(
       event_handler, sync_writer));
   controller->message_loop_ = audio_manager->GetMessageLoop();
 
+  // TODO(miu): See TODO at top of file.  Until that's resolved, we need to
+  // disable the error auto-detection here (since the audio mirroring
+  // implementation will reliably report error and close events).  Note, of
+  // course, that we're assuming CreateForStream() has been called for the audio
+  // mirroring use case only.
   if (!controller->message_loop_->PostTask(
           FROM_HERE,
           base::Bind(&AudioInputController::DoCreateForStream, controller,
-                     stream))) {
+                     stream, false))) {
     controller = NULL;
   }
 
@@ -160,11 +168,16 @@ void AudioInputController::DoCreate(AudioManager* audio_manager,
                                     const AudioParameters& params,
                                     const std::string& device_id) {
   DCHECK(message_loop_->BelongsToCurrentThread());
-  DoCreateForStream(audio_manager->MakeAudioInputStream(params, device_id));
+  // TODO(miu): See TODO at top of file.  Until that's resolved, assume all
+  // platform audio input requires the |no_data_timer_| be used to auto-detect
+  // errors.  In reality, probably only Windows and IOS need to be treated as
+  // unreliable here.
+  DoCreateForStream(audio_manager->MakeAudioInputStream(params, device_id),
+                    true);
 }
 
 void AudioInputController::DoCreateForStream(
-    AudioInputStream* stream_to_control) {
+    AudioInputStream* stream_to_control, bool enable_nodata_timer) {
   DCHECK(message_loop_->BelongsToCurrentThread());
 
   DCHECK(!stream_);
@@ -183,12 +196,18 @@ void AudioInputController::DoCreateForStream(
   }
 
   DCHECK(!no_data_timer_.get());
-  // Create the data timer which will call DoCheckForNoData(). The timer
-  // is started in DoRecord() and restarted in each DoCheckForNoData() callback.
-  no_data_timer_.reset(new base::Timer(
-      FROM_HERE, base::TimeDelta::FromSeconds(kTimerInitialIntervalSeconds),
-      base::Bind(&AudioInputController::DoCheckForNoData,
-      base::Unretained(this)), false));
+  if (enable_nodata_timer) {
+    // Create the data timer which will call DoCheckForNoData(). The timer
+    // is started in DoRecord() and restarted in each DoCheckForNoData()
+    // callback.
+    no_data_timer_.reset(new base::Timer(
+        FROM_HERE, base::TimeDelta::FromSeconds(kTimerInitialIntervalSeconds),
+        base::Bind(&AudioInputController::DoCheckForNoData,
+                   base::Unretained(this)), false));
+  } else {
+    DVLOG(1) << "Disabled: timer check for no data.";
+  }
+
   state_ = kCreated;
   handler_->OnCreated(this);
 }
@@ -204,9 +223,11 @@ void AudioInputController::DoRecord() {
     state_ = kRecording;
   }
 
-  // Start the data timer. Once |kTimerResetIntervalSeconds| have passed,
-  // a callback to DoCheckForNoData() is made.
-  no_data_timer_->Reset();
+  if (no_data_timer_) {
+    // Start the data timer. Once |kTimerResetIntervalSeconds| have passed,
+    // a callback to DoCheckForNoData() is made.
+    no_data_timer_->Reset();
+  }
 
   stream_->Start(this);
   handler_->OnRecording(this);