src/starboard/android/shared/microphone_impl.cc - cobalt - Git at Google

 // Copyright 2018 The Cobalt Authors. All Rights Reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 #include "starboard/shared/starboard/microphone/microphone_internal.h"

 #include <SLES/OpenSLES.h>
 #include <SLES/OpenSLES_Android.h>

 #include <algorithm>
 #include <queue>

 #include "starboard/android/shared/jni_env_ext.h"
 #include "starboard/common/log.h"
 #include "starboard/common/scoped_ptr.h"
 #include "starboard/memory.h"
 #include "starboard/shared/starboard/thread_checker.h"

 using starboard::android::shared::JniEnvExt;

 namespace starboard {
 namespace android {
 namespace shared {
 namespace {

 const int kSampleRateInHz = 16000;
 const int kSampleRateInMillihertz = kSampleRateInHz * 1000;
 const int kNumOfOpenSLESBuffers = 2;
 const int kSamplesPerBuffer = 128;
 const int kBufferSizeInBytes = kSamplesPerBuffer * sizeof(int16_t);

 bool CheckReturnValue(SLresult result) {
   return result == SL_RESULT_SUCCESS;
 }
 }  // namespace

 class SbMicrophoneImpl : public SbMicrophonePrivate {
  public:
   SbMicrophoneImpl();
   ~SbMicrophoneImpl() override;

   bool Open() override;
   bool Close() override;
   int Read(void* out_audio_data, int audio_data_size) override;

   void SetPermission(bool is_granted);
   static bool IsMicrophoneDisconnected();
   static bool IsMicrophoneMute();

  private:
   enum State { kWaitPermission, kPermissionGranted, kOpened, kClosed };

   static void SwapAndPublishBuffer(SLAndroidSimpleBufferQueueItf buffer_object,
                                    void* context);
   void SwapAndPublishBuffer();

   bool CreateAudioRecorder();
   void DeleteAudioRecorder();

   void ClearBuffer();

   bool RequestAudioPermission();
   bool StartRecording();
   bool StopRecording();

   SLObjectItf engine_object_;
   SLEngineItf engine_;
   SLObjectItf recorder_object_;
   SLRecordItf recorder_;
   SLAndroidSimpleBufferQueueItf buffer_object_;
   SLAndroidConfigurationItf config_object_;

   // Keeps track of the microphone's current state.
   State state_;
   // Audio data that has been delivered to the buffer queue.
   std::queue<int16_t*> delivered_queue_;
   // Audio data that is ready to be read.
   std::queue<int16_t*> ready_queue_;
 };

 SbMicrophoneImpl::SbMicrophoneImpl()
     : engine_object_(nullptr),
       engine_(nullptr),
       recorder_object_(nullptr),
       recorder_(nullptr),
       buffer_object_(nullptr),
       config_object_(nullptr),
       state_(kClosed) {}

 SbMicrophoneImpl::~SbMicrophoneImpl() {
   Close();
 }

 bool SbMicrophoneImpl::RequestAudioPermission() {
   JniEnvExt* env = JniEnvExt::Get();
   jobject j_audio_permission_requester =
       static_cast<jobject>(env->CallStarboardObjectMethodOrAbort(
           "getAudioPermissionRequester",
           "()Ldev/cobalt/coat/AudioPermissionRequester;"));
   jboolean j_permission = env->CallBooleanMethodOrAbort(
       j_audio_permission_requester, "requestRecordAudioPermission", "(J)Z",
       reinterpret_cast<intptr_t>(this));
   return j_permission;
 }

 // static
 bool SbMicrophoneImpl::IsMicrophoneDisconnected() {
   JniEnvExt* env = JniEnvExt::Get();
   jboolean j_microphone =
       env->CallStarboardBooleanMethodOrAbort("isMicrophoneDisconnected", "()Z");
   return j_microphone;
 }

 // static
 bool SbMicrophoneImpl::IsMicrophoneMute() {
   JniEnvExt* env = JniEnvExt::Get();
   jboolean j_microphone =
       env->CallStarboardBooleanMethodOrAbort("isMicrophoneMute", "()Z");
   return j_microphone;
 }

 bool SbMicrophoneImpl::Open() {
   if (state_ == kOpened) {
     // The microphone has already been opened; clear the unread buffer. See
     // starboard/microphone.h for more info.
     ClearBuffer();
     return true;
   }

   if (IsMicrophoneDisconnected()) {
     SB_DLOG(WARNING) << "No microphone connected.";
     return false;
   } else if (!RequestAudioPermission()) {
     state_ = kWaitPermission;
     SB_DLOG(INFO) << "Waiting for audio permission.";
     // The permission is not set; this causes the MicrophoneManager to call
     // read() repeatedly and wait for the user's response.
     return true;
   } else if (!StartRecording()) {
     SB_DLOG(WARNING) << "Error starting recording.";
     return false;
   }

   // Successfully opened the microphone and started recording.
   state_ = kOpened;
   return true;
 }

 bool SbMicrophoneImpl::StartRecording() {
   if (!CreateAudioRecorder()) {
     SB_DLOG(WARNING) << "Create audio recorder failed.";
     DeleteAudioRecorder();
     return false;
   }

   // Enqueues kNumOfOpenSLESBuffers zero buffers to start.
   // Adds buffers to the queue before changing state to ensure that recording
   // starts as soon as the state is modified.
   for (int i = 0; i < kNumOfOpenSLESBuffers; ++i) {
     int16_t* buffer = new int16_t[kSamplesPerBuffer];
     SbMemorySet(buffer, 0, kBufferSizeInBytes);
     delivered_queue_.push(buffer);
     SLresult result =
         (*buffer_object_)->Enqueue(buffer_object_, buffer, kBufferSizeInBytes);
     if (!CheckReturnValue(result)) {
       SB_DLOG(WARNING) << "Error adding buffers to the queue.";
       return false;
     }
   }

   // Start the recording by setting the state to |SL_RECORDSTATE_RECORDING|.
   // When the object is in the SL_RECORDSTATE_RECORDING state, adding buffers
   // will implicitly start the recording process.
   SLresult result =
       (*recorder_)->SetRecordState(recorder_, SL_RECORDSTATE_RECORDING);
   if (!CheckReturnValue(result)) {
     return false;
   }

   return true;
 }

 bool SbMicrophoneImpl::Close() {
   if (state_ == kClosed) {
     // The microphone has already been closed.
     return true;
   }

   if (state_ == kOpened && !StopRecording()) {
     SB_DLOG(WARNING) << "Error closing the microphone.";
     return false;
   }

   // Successfully closed the microphone and stopped recording.
   state_ = kClosed;
   return true;
 }

 bool SbMicrophoneImpl::StopRecording() {
   // Stop recording by setting the record state to |SL_RECORDSTATE_STOPPED|.
   SLresult result =
       (*recorder_)->SetRecordState(recorder_, SL_RECORDSTATE_STOPPED);
   if (!CheckReturnValue(result)) {
     return false;
   }

   ClearBuffer();

   DeleteAudioRecorder();

   return true;
 }

 int SbMicrophoneImpl::Read(void* out_audio_data, int audio_data_size) {
   if (state_ == kClosed || IsMicrophoneMute()) {
     // No audio data is read from a stopped or muted microphone; return an
     // error.
     return -1;
   }

   if (!out_audio_data || audio_data_size == 0 || state_ == kWaitPermission) {
     // No data to be read.
     return 0;
   }

   if (state_ == kPermissionGranted) {
     if (StartRecording()) {
       state_ = kOpened;
     } else {
       // Could not start recording; return an error.
       state_ = kClosed;
       return -1;
     }
   }

   int read_bytes = 0;
   scoped_ptr<int16_t> buffer;
   // Go through the ready queue, reading and sending audio data.
   while (!ready_queue_.empty() &&
          audio_data_size - read_bytes >= kBufferSizeInBytes) {
     buffer.reset(ready_queue_.front());
     SbMemoryCopy(static_cast<uint8_t*>(out_audio_data) + read_bytes,
                  buffer.get(), kBufferSizeInBytes);
     ready_queue_.pop();
     read_bytes += kBufferSizeInBytes;
   }

   buffer.reset();
   return read_bytes;
 }

 void SbMicrophoneImpl::SetPermission(bool is_granted) {
   state_ = is_granted ? kPermissionGranted : kClosed;
 }

 // static
 void SbMicrophoneImpl::SwapAndPublishBuffer(
     SLAndroidSimpleBufferQueueItf buffer_object,
     void* context) {
   SbMicrophoneImpl* recorder = static_cast<SbMicrophoneImpl*>(context);
   recorder->SwapAndPublishBuffer();
 }

 void SbMicrophoneImpl::SwapAndPublishBuffer() {
   if (!delivered_queue_.empty()) {
     // The front item in the delivered queue already has the buffered data, so
     // move it from the delivered queue to the ready queue for future reads.
     int16_t* buffer = delivered_queue_.front();
     delivered_queue_.pop();
     ready_queue_.push(buffer);
   }

   if (state_ == kOpened) {
     int16_t* buffer = new int16_t[kSamplesPerBuffer];
     SbMemorySet(buffer, 0, kBufferSizeInBytes);
     delivered_queue_.push(buffer);
     SLresult result =
         (*buffer_object_)->Enqueue(buffer_object_, buffer, kBufferSizeInBytes);
     CheckReturnValue(result);
   }
 }

 bool SbMicrophoneImpl::CreateAudioRecorder() {
   SLresult result;
   // Initializes the SL engine object with specific options.
   // OpenSL ES for Android is designed for multi-threaded applications and
   // is thread-safe.
   result = slCreateEngine(&engine_object_, 0, nullptr, 0, nullptr, nullptr);
   if (!CheckReturnValue(result)) {
     SB_DLOG(WARNING) << "Error creating the SL engine object.";
     return false;
   }

   // Realize the SL engine object in synchronous mode.
   result = (*engine_object_)
                ->Realize(engine_object_, /* async = */ SL_BOOLEAN_FALSE);
   if (!CheckReturnValue(result)) {
     SB_DLOG(WARNING) << "Error realizing the SL engine object.";
     return false;
   }

   // Get the SL engine interface.
   result =
       (*engine_object_)->GetInterface(engine_object_, SL_IID_ENGINE, &engine_);
   if (!CheckReturnValue(result)) {
     SB_DLOG(WARNING) << "Error getting the SL engine interface.";
     return false;
   }

   // Audio source configuration; the audio source is an I/O device data locator.
   SLDataLocator_IODevice input_dev_locator = {
       SL_DATALOCATOR_IODEVICE, SL_IODEVICE_AUDIOINPUT,
       SL_DEFAULTDEVICEID_AUDIOINPUT, nullptr};

   SLDataSource audio_source = {&input_dev_locator, nullptr};
   SLDataLocator_AndroidSimpleBufferQueue simple_buffer_queue = {
       SL_DATALOCATOR_ANDROIDSIMPLEBUFFERQUEUE, kNumOfOpenSLESBuffers};

   // Audio sink configuration; the audio sink is a simple buffer queue. PCM is
   // the only data format allowed with buffer queues.
   SLAndroidDataFormat_PCM_EX format = {
       SL_ANDROID_DATAFORMAT_PCM_EX, 1 /* numChannels */,
       kSampleRateInMillihertz,      SL_PCMSAMPLEFORMAT_FIXED_16,
       SL_PCMSAMPLEFORMAT_FIXED_16,  SL_SPEAKER_FRONT_CENTER,
       SL_BYTEORDER_LITTLEENDIAN,    SL_ANDROID_PCM_REPRESENTATION_SIGNED_INT};
   SLDataSink audio_sink = {&simple_buffer_queue, &format};

   const int kCount = 2;
   const SLInterfaceID kInterfaceId[kCount] = {SL_IID_ANDROIDSIMPLEBUFFERQUEUE,
                                               SL_IID_ANDROIDCONFIGURATION};
   const SLboolean kInterfaceRequired[kCount] = {SL_BOOLEAN_TRUE,
                                                 SL_BOOLEAN_TRUE};
   // Create the audio recorder.
   result = (*engine_)->CreateAudioRecorder(engine_, &recorder_object_,
                                            &audio_source, &audio_sink, kCount,
                                            kInterfaceId, kInterfaceRequired);
   if (!CheckReturnValue(result)) {
     SB_DLOG(WARNING) << "Error creating the audio recorder.";
     return false;
   }

   // Configure the audio recorder (before it is realized); get the configuration
   // interface.
   result = (*recorder_object_)
                ->GetInterface(recorder_object_, SL_IID_ANDROIDCONFIGURATION,
                               &config_object_);
   if (!CheckReturnValue(result)) {
     SB_DLOG(WARNING) << "Error getting the audio recorder interface.";
     return false;
   }

   // Use the main microphone tuned for voice recognition.
   const SLuint32 kPresetValue = SL_ANDROID_RECORDING_PRESET_VOICE_RECOGNITION;
   result =
       (*config_object_)
           ->SetConfiguration(config_object_, SL_ANDROID_KEY_RECORDING_PRESET,
                              &kPresetValue, sizeof(SLuint32));
   if (!CheckReturnValue(result)) {
     SB_DLOG(WARNING) << "Error configuring the audio recorder.";
     return false;
   }

   // Realize the recorder in synchronous mode.
   result = (*recorder_object_)
                ->Realize(recorder_object_, /* async = */ SL_BOOLEAN_FALSE);
   if (!CheckReturnValue(result)) {
     SB_DLOG(WARNING) << "Error realizing the audio recorder. Double check that "
                         "the microphone is connected to the device.";
     return false;
   }

   // Get the record interface (an implicit interface).
   result = (*recorder_object_)
                ->GetInterface(recorder_object_, SL_IID_RECORD, &recorder_);
   if (!CheckReturnValue(result)) {
     SB_DLOG(WARNING) << "Error getting the audio recorder interface.";
     return false;
   }

   // Get the buffer queue interface which was explicitly requested.
   result = (*recorder_object_)
                ->GetInterface(recorder_object_, SL_IID_ANDROIDSIMPLEBUFFERQUEUE,
                               &buffer_object_);
   if (!CheckReturnValue(result)) {
     SB_DLOG(WARNING) << "Error getting the buffer queue interface.";
     return false;
   }

   // Setup to receive buffer queue event callbacks for when a buffer in the
   // queue is completed.
   result =
       (*buffer_object_)
           ->RegisterCallback(buffer_object_,
                              &SbMicrophoneImpl::SwapAndPublishBuffer, this);
   if (!CheckReturnValue(result)) {
     SB_DLOG(WARNING) << "Error registering buffer queue callbacks.";
     return false;
   }

   return true;
 }

 void SbMicrophoneImpl::DeleteAudioRecorder() {
   if (recorder_object_) {
     (*recorder_object_)->Destroy(recorder_object_);
   }

   config_object_ = nullptr;
   buffer_object_ = nullptr;
   recorder_ = nullptr;
   recorder_object_ = nullptr;

   // Destroy the engine object.
   if (engine_object_) {
     (*engine_object_)->Destroy(engine_object_);
   }
   engine_ = nullptr;
   engine_object_ = nullptr;
 }

 void SbMicrophoneImpl::ClearBuffer() {
   // Clear the buffer queue to get rid of old data.
   if (buffer_object_) {
     SLresult result = (*buffer_object_)->Clear(buffer_object_);
     if (!CheckReturnValue(result)) {
       SB_DLOG(WARNING) << "Error clearing the buffer.";
     }
   }

   while (!delivered_queue_.empty()) {
     delete[] delivered_queue_.front();
     delivered_queue_.pop();
   }

   while (!ready_queue_.empty()) {
     delete[] ready_queue_.front();
     ready_queue_.pop();
   }
 }

 }  // namespace shared
 }  // namespace android
 }  // namespace starboard

 int SbMicrophonePrivate::GetAvailableMicrophones(
     SbMicrophoneInfo* out_info_array,
     int info_array_size) {
   // Note that there is no way of checking for a connected microphone/device
   // before API 23, so GetAvailableMicrophones() will assume a microphone is
   // connected and always return 1 on APIs < 23.
   if (starboard::android::shared::SbMicrophoneImpl::
           IsMicrophoneDisconnected()) {
     SB_DLOG(WARNING) << "No microphone connected.";
     return 0;
   }
   if (starboard::android::shared::SbMicrophoneImpl::IsMicrophoneMute()) {
     SB_DLOG(WARNING) << "Microphone is muted.";
     return 0;
   }

   if (out_info_array && info_array_size > 0) {
     // Only support one microphone.
     out_info_array[0].id = reinterpret_cast<SbMicrophoneId>(1);
     out_info_array[0].type = kSbMicrophoneUnknown;
     out_info_array[0].max_sample_rate_hz =
         starboard::android::shared::kSampleRateInHz;
     out_info_array[0].min_read_size =
         starboard::android::shared::kSamplesPerBuffer;
   }

   return 1;
 }

 bool SbMicrophonePrivate::IsMicrophoneSampleRateSupported(
     SbMicrophoneId id,
     int sample_rate_in_hz) {
   if (!SbMicrophoneIdIsValid(id)) {
     return false;
   }

   return sample_rate_in_hz == starboard::android::shared::kSampleRateInHz;
 }

 namespace {
 const int kUnusedBufferSize = 32 * 1024;
 // Only a single microphone is supported.
 SbMicrophone s_microphone = kSbMicrophoneInvalid;

 }  // namespace

 SbMicrophone SbMicrophonePrivate::CreateMicrophone(SbMicrophoneId id,
                                                    int sample_rate_in_hz,
                                                    int buffer_size_bytes) {
   if (!SbMicrophoneIdIsValid(id) ||
       !IsMicrophoneSampleRateSupported(id, sample_rate_in_hz) ||
       buffer_size_bytes > kUnusedBufferSize || buffer_size_bytes <= 0) {
     return kSbMicrophoneInvalid;
   }

   if (s_microphone != kSbMicrophoneInvalid) {
     return kSbMicrophoneInvalid;
   }

   s_microphone = new starboard::android::shared::SbMicrophoneImpl();
   return s_microphone;
 }

 void SbMicrophonePrivate::DestroyMicrophone(SbMicrophone microphone) {
   if (!SbMicrophoneIsValid(microphone)) {
     return;
   }

   SB_DCHECK(s_microphone == microphone);
   s_microphone->Close();

   delete s_microphone;
   s_microphone = kSbMicrophoneInvalid;
 }

 extern "C" SB_EXPORT_PLATFORM void
 Java_dev_cobalt_coat_AudioPermissionRequester_nativeHandlePermission(
     JNIEnv* env,
     jobject unused_this,
     jlong nativeSbMicrophoneImpl,
     jboolean is_granted) {
   starboard::android::shared::SbMicrophoneImpl* native =
       reinterpret_cast<starboard::android::shared::SbMicrophoneImpl*>(
           nativeSbMicrophoneImpl);
   native->SetPermission(is_granted);
 }
	// Copyright 2018 The Cobalt Authors. All Rights Reserved.
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	#include "starboard/shared/starboard/microphone/microphone_internal.h"

	#include <SLES/OpenSLES.h>
	#include <SLES/OpenSLES_Android.h>

	#include <algorithm>
	#include <queue>

	#include "starboard/android/shared/jni_env_ext.h"
	#include "starboard/common/log.h"
	#include "starboard/common/scoped_ptr.h"
	#include "starboard/memory.h"
	#include "starboard/shared/starboard/thread_checker.h"

	using starboard::android::shared::JniEnvExt;

	namespace starboard {
	namespace android {
	namespace shared {
	namespace {

	const int kSampleRateInHz = 16000;
	const int kSampleRateInMillihertz = kSampleRateInHz * 1000;
	const int kNumOfOpenSLESBuffers = 2;
	const int kSamplesPerBuffer = 128;
	const int kBufferSizeInBytes = kSamplesPerBuffer * sizeof(int16_t);

	bool CheckReturnValue(SLresult result) {
	return result == SL_RESULT_SUCCESS;
	}
	} // namespace

	class SbMicrophoneImpl : public SbMicrophonePrivate {
	public:
	SbMicrophoneImpl();
	~SbMicrophoneImpl() override;

	bool Open() override;
	bool Close() override;
	int Read(void* out_audio_data, int audio_data_size) override;

	void SetPermission(bool is_granted);
	static bool IsMicrophoneDisconnected();
	static bool IsMicrophoneMute();

	private:
	enum State { kWaitPermission, kPermissionGranted, kOpened, kClosed };

	static void SwapAndPublishBuffer(SLAndroidSimpleBufferQueueItf buffer_object,
	void* context);
	void SwapAndPublishBuffer();

	bool CreateAudioRecorder();
	void DeleteAudioRecorder();

	void ClearBuffer();

	bool RequestAudioPermission();
	bool StartRecording();
	bool StopRecording();

	SLObjectItf engine_object_;
	SLEngineItf engine_;
	SLObjectItf recorder_object_;
	SLRecordItf recorder_;
	SLAndroidSimpleBufferQueueItf buffer_object_;
	SLAndroidConfigurationItf config_object_;

	// Keeps track of the microphone's current state.
	State state_;
	// Audio data that has been delivered to the buffer queue.
	std::queue<int16_t*> delivered_queue_;
	// Audio data that is ready to be read.
	std::queue<int16_t*> ready_queue_;
	};

	SbMicrophoneImpl::SbMicrophoneImpl()
	: engine_object_(nullptr),
	engine_(nullptr),
	recorder_object_(nullptr),
	recorder_(nullptr),
	buffer_object_(nullptr),
	config_object_(nullptr),
	state_(kClosed) {}

	SbMicrophoneImpl::~SbMicrophoneImpl() {
	Close();
	}

	bool SbMicrophoneImpl::RequestAudioPermission() {
	JniEnvExt* env = JniEnvExt::Get();
	jobject j_audio_permission_requester =
	static_cast<jobject>(env->CallStarboardObjectMethodOrAbort(
	"getAudioPermissionRequester",
	"()Ldev/cobalt/coat/AudioPermissionRequester;"));
	jboolean j_permission = env->CallBooleanMethodOrAbort(
	j_audio_permission_requester, "requestRecordAudioPermission", "(J)Z",
	reinterpret_cast<intptr_t>(this));
	return j_permission;
	}

	// static
	bool SbMicrophoneImpl::IsMicrophoneDisconnected() {
	JniEnvExt* env = JniEnvExt::Get();
	jboolean j_microphone =
	env->CallStarboardBooleanMethodOrAbort("isMicrophoneDisconnected", "()Z");
	return j_microphone;
	}

	// static
	bool SbMicrophoneImpl::IsMicrophoneMute() {
	JniEnvExt* env = JniEnvExt::Get();
	jboolean j_microphone =
	env->CallStarboardBooleanMethodOrAbort("isMicrophoneMute", "()Z");
	return j_microphone;
	}

	bool SbMicrophoneImpl::Open() {
	if (state_ == kOpened) {
	// The microphone has already been opened; clear the unread buffer. See
	// starboard/microphone.h for more info.
	ClearBuffer();
	return true;
	}

	if (IsMicrophoneDisconnected()) {
	SB_DLOG(WARNING) << "No microphone connected.";
	return false;
	} else if (!RequestAudioPermission()) {
	state_ = kWaitPermission;
	SB_DLOG(INFO) << "Waiting for audio permission.";
	// The permission is not set; this causes the MicrophoneManager to call
	// read() repeatedly and wait for the user's response.
	return true;
	} else if (!StartRecording()) {
	SB_DLOG(WARNING) << "Error starting recording.";
	return false;
	}

	// Successfully opened the microphone and started recording.
	state_ = kOpened;
	return true;
	}

	bool SbMicrophoneImpl::StartRecording() {
	if (!CreateAudioRecorder()) {
	SB_DLOG(WARNING) << "Create audio recorder failed.";
	DeleteAudioRecorder();
	return false;
	}

	// Enqueues kNumOfOpenSLESBuffers zero buffers to start.
	// Adds buffers to the queue before changing state to ensure that recording
	// starts as soon as the state is modified.
	for (int i = 0; i < kNumOfOpenSLESBuffers; ++i) {
	int16_t* buffer = new int16_t[kSamplesPerBuffer];
	SbMemorySet(buffer, 0, kBufferSizeInBytes);
	delivered_queue_.push(buffer);
	SLresult result =
	(*buffer_object_)->Enqueue(buffer_object_, buffer, kBufferSizeInBytes);
	if (!CheckReturnValue(result)) {
	SB_DLOG(WARNING) << "Error adding buffers to the queue.";
	return false;
	}
	}

	// Start the recording by setting the state to \|SL_RECORDSTATE_RECORDING\|.
	// When the object is in the SL_RECORDSTATE_RECORDING state, adding buffers
	// will implicitly start the recording process.
	SLresult result =
	(*recorder_)->SetRecordState(recorder_, SL_RECORDSTATE_RECORDING);
	if (!CheckReturnValue(result)) {
	return false;
	}

	return true;
	}

	bool SbMicrophoneImpl::Close() {
	if (state_ == kClosed) {
	// The microphone has already been closed.
	return true;
	}

	if (state_ == kOpened && !StopRecording()) {
	SB_DLOG(WARNING) << "Error closing the microphone.";
	return false;
	}

	// Successfully closed the microphone and stopped recording.
	state_ = kClosed;
	return true;
	}

	bool SbMicrophoneImpl::StopRecording() {
	// Stop recording by setting the record state to \|SL_RECORDSTATE_STOPPED\|.
	SLresult result =
	(*recorder_)->SetRecordState(recorder_, SL_RECORDSTATE_STOPPED);
	if (!CheckReturnValue(result)) {
	return false;
	}

	ClearBuffer();

	DeleteAudioRecorder();

	return true;
	}

	int SbMicrophoneImpl::Read(void* out_audio_data, int audio_data_size) {
	if (state_ == kClosed \|\| IsMicrophoneMute()) {
	// No audio data is read from a stopped or muted microphone; return an
	// error.
	return -1;
	}

	if (!out_audio_data \|\| audio_data_size == 0 \|\| state_ == kWaitPermission) {
	// No data to be read.
	return 0;
	}

	if (state_ == kPermissionGranted) {
	if (StartRecording()) {
	state_ = kOpened;
	} else {
	// Could not start recording; return an error.
	state_ = kClosed;
	return -1;
	}
	}

	int read_bytes = 0;
	scoped_ptr<int16_t> buffer;
	// Go through the ready queue, reading and sending audio data.
	while (!ready_queue_.empty() &&
	audio_data_size - read_bytes >= kBufferSizeInBytes) {
	buffer.reset(ready_queue_.front());
	SbMemoryCopy(static_cast<uint8_t*>(out_audio_data) + read_bytes,
	buffer.get(), kBufferSizeInBytes);
	ready_queue_.pop();
	read_bytes += kBufferSizeInBytes;
	}

	buffer.reset();
	return read_bytes;
	}

	void SbMicrophoneImpl::SetPermission(bool is_granted) {
	state_ = is_granted ? kPermissionGranted : kClosed;
	}

	// static
	void SbMicrophoneImpl::SwapAndPublishBuffer(
	SLAndroidSimpleBufferQueueItf buffer_object,
	void* context) {
	SbMicrophoneImpl* recorder = static_cast<SbMicrophoneImpl*>(context);
	recorder->SwapAndPublishBuffer();
	}

	void SbMicrophoneImpl::SwapAndPublishBuffer() {
	if (!delivered_queue_.empty()) {
	// The front item in the delivered queue already has the buffered data, so
	// move it from the delivered queue to the ready queue for future reads.
	int16_t* buffer = delivered_queue_.front();
	delivered_queue_.pop();
	ready_queue_.push(buffer);
	}

	if (state_ == kOpened) {
	int16_t* buffer = new int16_t[kSamplesPerBuffer];
	SbMemorySet(buffer, 0, kBufferSizeInBytes);
	delivered_queue_.push(buffer);
	SLresult result =
	(*buffer_object_)->Enqueue(buffer_object_, buffer, kBufferSizeInBytes);
	CheckReturnValue(result);
	}
	}

	bool SbMicrophoneImpl::CreateAudioRecorder() {
	SLresult result;
	// Initializes the SL engine object with specific options.
	// OpenSL ES for Android is designed for multi-threaded applications and
	// is thread-safe.
	result = slCreateEngine(&engine_object_, 0, nullptr, 0, nullptr, nullptr);
	if (!CheckReturnValue(result)) {
	SB_DLOG(WARNING) << "Error creating the SL engine object.";
	return false;
	}

	// Realize the SL engine object in synchronous mode.
	result = (*engine_object_)
	->Realize(engine_object_, /* async = */ SL_BOOLEAN_FALSE);
	if (!CheckReturnValue(result)) {
	SB_DLOG(WARNING) << "Error realizing the SL engine object.";
	return false;
	}

	// Get the SL engine interface.
	result =
	(*engine_object_)->GetInterface(engine_object_, SL_IID_ENGINE, &engine_);
	if (!CheckReturnValue(result)) {
	SB_DLOG(WARNING) << "Error getting the SL engine interface.";
	return false;
	}

	// Audio source configuration; the audio source is an I/O device data locator.
	SLDataLocator_IODevice input_dev_locator = {
	SL_DATALOCATOR_IODEVICE, SL_IODEVICE_AUDIOINPUT,
	SL_DEFAULTDEVICEID_AUDIOINPUT, nullptr};

	SLDataSource audio_source = {&input_dev_locator, nullptr};
	SLDataLocator_AndroidSimpleBufferQueue simple_buffer_queue = {
	SL_DATALOCATOR_ANDROIDSIMPLEBUFFERQUEUE, kNumOfOpenSLESBuffers};

	// Audio sink configuration; the audio sink is a simple buffer queue. PCM is
	// the only data format allowed with buffer queues.
	SLAndroidDataFormat_PCM_EX format = {
	SL_ANDROID_DATAFORMAT_PCM_EX, 1 /* numChannels */,
	kSampleRateInMillihertz, SL_PCMSAMPLEFORMAT_FIXED_16,
	SL_PCMSAMPLEFORMAT_FIXED_16, SL_SPEAKER_FRONT_CENTER,
	SL_BYTEORDER_LITTLEENDIAN, SL_ANDROID_PCM_REPRESENTATION_SIGNED_INT};
	SLDataSink audio_sink = {&simple_buffer_queue, &format};

	const int kCount = 2;
	const SLInterfaceID kInterfaceId[kCount] = {SL_IID_ANDROIDSIMPLEBUFFERQUEUE,
	SL_IID_ANDROIDCONFIGURATION};
	const SLboolean kInterfaceRequired[kCount] = {SL_BOOLEAN_TRUE,
	SL_BOOLEAN_TRUE};
	// Create the audio recorder.
	result = (*engine_)->CreateAudioRecorder(engine_, &recorder_object_,
	&audio_source, &audio_sink, kCount,
	kInterfaceId, kInterfaceRequired);
	if (!CheckReturnValue(result)) {
	SB_DLOG(WARNING) << "Error creating the audio recorder.";
	return false;
	}

	// Configure the audio recorder (before it is realized); get the configuration
	// interface.
	result = (*recorder_object_)
	->GetInterface(recorder_object_, SL_IID_ANDROIDCONFIGURATION,
	&config_object_);
	if (!CheckReturnValue(result)) {
	SB_DLOG(WARNING) << "Error getting the audio recorder interface.";
	return false;
	}

	// Use the main microphone tuned for voice recognition.
	const SLuint32 kPresetValue = SL_ANDROID_RECORDING_PRESET_VOICE_RECOGNITION;
	result =
	(*config_object_)
	->SetConfiguration(config_object_, SL_ANDROID_KEY_RECORDING_PRESET,
	&kPresetValue, sizeof(SLuint32));
	if (!CheckReturnValue(result)) {
	SB_DLOG(WARNING) << "Error configuring the audio recorder.";
	return false;
	}

	// Realize the recorder in synchronous mode.
	result = (*recorder_object_)
	->Realize(recorder_object_, /* async = */ SL_BOOLEAN_FALSE);
	if (!CheckReturnValue(result)) {
	SB_DLOG(WARNING) << "Error realizing the audio recorder. Double check that "
	"the microphone is connected to the device.";
	return false;
	}

	// Get the record interface (an implicit interface).
	result = (*recorder_object_)
	->GetInterface(recorder_object_, SL_IID_RECORD, &recorder_);
	if (!CheckReturnValue(result)) {
	SB_DLOG(WARNING) << "Error getting the audio recorder interface.";
	return false;
	}

	// Get the buffer queue interface which was explicitly requested.
	result = (*recorder_object_)
	->GetInterface(recorder_object_, SL_IID_ANDROIDSIMPLEBUFFERQUEUE,
	&buffer_object_);
	if (!CheckReturnValue(result)) {
	SB_DLOG(WARNING) << "Error getting the buffer queue interface.";
	return false;
	}

	// Setup to receive buffer queue event callbacks for when a buffer in the
	// queue is completed.
	result =
	(*buffer_object_)
	->RegisterCallback(buffer_object_,
	&SbMicrophoneImpl::SwapAndPublishBuffer, this);
	if (!CheckReturnValue(result)) {
	SB_DLOG(WARNING) << "Error registering buffer queue callbacks.";
	return false;
	}

	return true;
	}

	void SbMicrophoneImpl::DeleteAudioRecorder() {
	if (recorder_object_) {
	(*recorder_object_)->Destroy(recorder_object_);
	}

	config_object_ = nullptr;
	buffer_object_ = nullptr;
	recorder_ = nullptr;
	recorder_object_ = nullptr;

	// Destroy the engine object.
	if (engine_object_) {
	(*engine_object_)->Destroy(engine_object_);
	}
	engine_ = nullptr;
	engine_object_ = nullptr;
	}

	void SbMicrophoneImpl::ClearBuffer() {
	// Clear the buffer queue to get rid of old data.
	if (buffer_object_) {
	SLresult result = (*buffer_object_)->Clear(buffer_object_);
	if (!CheckReturnValue(result)) {
	SB_DLOG(WARNING) << "Error clearing the buffer.";
	}
	}

	while (!delivered_queue_.empty()) {
	delete[] delivered_queue_.front();
	delivered_queue_.pop();
	}

	while (!ready_queue_.empty()) {
	delete[] ready_queue_.front();
	ready_queue_.pop();
	}
	}

	} // namespace shared
	} // namespace android
	} // namespace starboard

	int SbMicrophonePrivate::GetAvailableMicrophones(
	SbMicrophoneInfo* out_info_array,
	int info_array_size) {
	// Note that there is no way of checking for a connected microphone/device
	// before API 23, so GetAvailableMicrophones() will assume a microphone is
	// connected and always return 1 on APIs < 23.
	if (starboard::android::shared::SbMicrophoneImpl::
	IsMicrophoneDisconnected()) {
	SB_DLOG(WARNING) << "No microphone connected.";
	return 0;
	}
	if (starboard::android::shared::SbMicrophoneImpl::IsMicrophoneMute()) {
	SB_DLOG(WARNING) << "Microphone is muted.";
	return 0;
	}

	if (out_info_array && info_array_size > 0) {
	// Only support one microphone.
	out_info_array[0].id = reinterpret_cast<SbMicrophoneId>(1);
	out_info_array[0].type = kSbMicrophoneUnknown;
	out_info_array[0].max_sample_rate_hz =
	starboard::android::shared::kSampleRateInHz;
	out_info_array[0].min_read_size =
	starboard::android::shared::kSamplesPerBuffer;
	}

	return 1;
	}

	bool SbMicrophonePrivate::IsMicrophoneSampleRateSupported(
	SbMicrophoneId id,
	int sample_rate_in_hz) {
	if (!SbMicrophoneIdIsValid(id)) {
	return false;
	}

	return sample_rate_in_hz == starboard::android::shared::kSampleRateInHz;
	}

	namespace {
	const int kUnusedBufferSize = 32 * 1024;
	// Only a single microphone is supported.
	SbMicrophone s_microphone = kSbMicrophoneInvalid;

	} // namespace

	SbMicrophone SbMicrophonePrivate::CreateMicrophone(SbMicrophoneId id,
	int sample_rate_in_hz,
	int buffer_size_bytes) {
	if (!SbMicrophoneIdIsValid(id) \|\|
	!IsMicrophoneSampleRateSupported(id, sample_rate_in_hz) \|\|
	buffer_size_bytes > kUnusedBufferSize \|\| buffer_size_bytes <= 0) {
	return kSbMicrophoneInvalid;
	}

	if (s_microphone != kSbMicrophoneInvalid) {
	return kSbMicrophoneInvalid;
	}

	s_microphone = new starboard::android::shared::SbMicrophoneImpl();
	return s_microphone;
	}

	void SbMicrophonePrivate::DestroyMicrophone(SbMicrophone microphone) {
	if (!SbMicrophoneIsValid(microphone)) {
	return;
	}

	SB_DCHECK(s_microphone == microphone);
	s_microphone->Close();

	delete s_microphone;
	s_microphone = kSbMicrophoneInvalid;
	}

	extern "C" SB_EXPORT_PLATFORM void
	Java_dev_cobalt_coat_AudioPermissionRequester_nativeHandlePermission(
	JNIEnv* env,
	jobject unused_this,
	jlong nativeSbMicrophoneImpl,
	jboolean is_granted) {
	starboard::android::shared::SbMicrophoneImpl* native =
	reinterpret_cast<starboard::android::shared::SbMicrophoneImpl*>(
	nativeSbMicrophoneImpl);
	native->SetPermission(is_granted);
	}