Stop enqueueing data to output audio device if consecutive empty buffers are received

media/audio/android/opensles_output.h

 // 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.
 
 #ifndef MEDIA_AUDIO_ANDROID_OPENSLES_OUTPUT_H_
 #define MEDIA_AUDIO_ANDROID_OPENSLES_OUTPUT_H_
 
 #include <SLES/OpenSLES.h>
 #include <SLES/OpenSLES_Android.h>
 
+#include "base/cancelable_callback.h"
 #include "base/compiler_specific.h"
+#include "base/memory/weak_ptr.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/thread_checker.h"
+#include "base/time/time.h"
 #include "media/audio/android/opensles_util.h"
 #include "media/audio/audio_io.h"
 #include "media/audio/audio_parameters.h"
+#include "media/base/audio_timestamp_helper.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
 
 namespace media {
 
 class AudioManagerAndroid;
 
 // Implements PCM audio output support for Android using the OpenSLES API.
 // This class is created and lives on the Audio Manager thread but recorded
 // audio buffers are given to us from an internal OpenSLES audio thread.
 // All public methods should be called on the Audio Manager thread.
 class OpenSLESOutputStream : public AudioOutputStream {
@@ skipping 23 matching lines @@
 
   // Called from OpenSLES specific audio worker thread.
   static void SimpleBufferQueueCallback(
       SLAndroidSimpleBufferQueueItf buffer_queue,
       void* instance);
 
   // Fills up one buffer by asking the registered source for data.
   // Called from OpenSLES specific audio worker thread.
   void FillBufferQueue();
 
-  // Called from the audio manager thread.
-  void FillBufferQueueNoLock();
+  // Called from either the audio manager thread or the OpenSLES audio worker
+  // thread. |lock_| must be held when this method is called.
+  // |in_idle_mode| is true if the player is in idle mode, or false otherwise.
+  void FillBufferQueueNoLock(bool in_idle_mode);
 
   // Called in Open();
   void SetupAudioBuffer();
 
   // Called in Close();
   void ReleaseAudioBuffer();
 
   // If OpenSLES reports an error this function handles it and passes it to
   // the attached AudioOutputCallback::OnError().
   void HandleError(SLresult error);
 
+  // Called to check whether there are any audio data available to render.
+  void CheckForIdle();
+
+  // Called to cancel the check for empty audio data.
+  void CancelIdleCheck();
+
+  // Starts entering idle mode. The player will stop writing data to buffer
+  // queue until non empty data arrives. |in_idle_mode| indicates whether
+  // the player is in the idle mode. |frames_filled| and |idle_start_time|
+  // are used by |audio_timestamp_helper_| and |idle_start_time_| to avoid
+  // time drifting.
+  void WaitingForAudio(bool in_idle_mode,
+                       int frames_filled, base::TimeTicks idle_start_time);
+
   base::ThreadChecker thread_checker_;
 
   // Protects |callback_|, |active_buffer_index_|, |audio_data_|,
   // |buffer_size_bytes_| and |simple_buffer_queue_|.
   base::Lock lock_;
 
   AudioManagerAndroid* audio_manager_;
 
   // Audio playback stream type.
   // See SLES/OpenSLES_Android.h for details.
@@ skipping 27 matching lines @@
   // This is needed because platform voice volume never goes to zero in
   // COMMUNICATION mode on Android.
   bool muted_;
 
   // Volume level from 0 to 1.
   float volume_;
 
   // Container for retrieving data from AudioSourceCallback::OnMoreData().
   scoped_ptr<AudioBus> audio_bus_;
 
+  // Object to calculate the current audio timestamp in idle mode.
+  scoped_ptr<AudioTimestampHelper> audio_timestamp_helper_;
+
+  // The start TimeTicks when the player enters idle mode.
+  base::TimeTicks idle_start_time_;
+
+  // The number of consecutive empty audio buffers encountered.
+  uint32 consecutive_empty_buffer_count_;
+
+  // A cancelable task that is posted when the player enters idle mode. The task
+  // is posted regularly to check whether there are any audio data available to
+  // render.
+  base::CancelableClosure idle_check_callback_;
+
+  // TaskRunner to post |idle_check_callback_|.
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+
+  // Weak pointer for callbacks.
+  base::WeakPtr<OpenSLESOutputStream> weak_this_;
+  // NOTE: Weak pointers must be invalidated before all other member variables.
+  base::WeakPtrFactory<OpenSLESOutputStream> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(OpenSLESOutputStream);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_ANDROID_OPENSLES_OUTPUT_H_