Refactor audio manager for Android to avoid heavy tasks at startup

media/audio/android/audio_manager_android.cc

 // 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.
 
 #include "media/audio/android/audio_manager_android.h"
 
 #include "base/android/build_info.h"
 #include "base/android/jni_array.h"
 #include "base/android/jni_string.h"
 #include "base/android/scoped_java_ref.h"
@@ skipping 18 matching lines @@
 static void AddDefaultDevice(AudioDeviceNames* device_names) {
   DCHECK(device_names->empty());
   device_names->push_front(
       AudioDeviceName(AudioManagerBase::kDefaultDeviceName,
                       AudioManagerBase::kDefaultDeviceId));
 }
 
 // Maximum number of output streams that can be open simultaneously.
 static const int kMaxOutputStreams = 10;
 
-static const int kAudioModeNormal = 0x00000000;
-static const int kAudioModeInCommunication = 0x00000003;
-
 static const int kDefaultInputBufferSize = 1024;
 static const int kDefaultOutputBufferSize = 2048;
 
 AudioManager* CreateAudioManager(AudioLogFactory* audio_log_factory) {
   return new AudioManagerAndroid(audio_log_factory);
 }
 
 AudioManagerAndroid::AudioManagerAndroid(AudioLogFactory* audio_log_factory)
     : AudioManagerBase(audio_log_factory) {
   SetMaxOutputStreamsAllowed(kMaxOutputStreams);
@@ skipping 62 matching lines @@
   return AudioParameters(
       AudioParameters::AUDIO_PCM_LOW_LATENCY, channel_layout,
       GetNativeOutputSampleRate(), 16,
       buffer_size <= 0 ? kDefaultInputBufferSize : buffer_size);
 }
 
 AudioOutputStream* AudioManagerAndroid::MakeAudioOutputStream(
     const AudioParameters& params,
     const std::string& device_id,
     const std::string& input_device_id) {
+  bool has_no_streams = HasNoAudioStreams();
   AudioOutputStream* stream =
       AudioManagerBase::MakeAudioOutputStream(params, std::string(),
           std::string());
-  if (stream && output_stream_count() == 1) {
-    SetAudioMode(kAudioModeInCommunication);
+
+  // The audio manager for Android creates streams intended for real-time
+  // VoIP sessions and therefore sets the audio mode to MODE_IN_COMMUNICATION.
+  // If a Bluetooth headset is used, the audio stream will use the SCO
+  // channel and therefore have a limited bandwidth (8-16kHz).
+  if (stream && has_no_streams) {
+    SetCommunicationAudioModeOn(true);
   }
 
   {
     base::AutoLock lock(streams_lock_);
     streams_.insert(static_cast<OpenSLESOutputStream*>(stream));
   }
 
   return stream;
 }
 
 AudioInputStream* AudioManagerAndroid::MakeAudioInputStream(
     const AudioParameters& params, const std::string& device_id) {
+  bool has_no_streams = HasNoAudioStreams();
   AudioInputStream* stream =
       AudioManagerBase::MakeAudioInputStream(params, device_id);
+
+  // The audio manager for Android creates streams intended for real-time
+  // VoIP sessions and therefore sets the audio mode to MODE_IN_COMMUNICATION.
+  // If a Bluetooth headset is used, the audio stream will use the SCO
+  // channel and therefore have a limited bandwidth (8kHz).
+  if (stream && has_no_streams) {
+    SetCommunicationAudioModeOn(true);
+  }
   return stream;
 }
 
 void AudioManagerAndroid::ReleaseOutputStream(AudioOutputStream* stream) {
   AudioManagerBase::ReleaseOutputStream(stream);
-  if (!output_stream_count()) {
-    SetAudioMode(kAudioModeNormal);
+
+  // Restore the audio mode which was used before the first communication-
+  // mode stream was created.
+  if (HasNoAudioStreams()) {
+    SetCommunicationAudioModeOn(false);
   }
   base::AutoLock lock(streams_lock_);
   streams_.erase(static_cast<OpenSLESOutputStream*>(stream));
 }
 
 void AudioManagerAndroid::ReleaseInputStream(AudioInputStream* stream) {
   AudioManagerBase::ReleaseInputStream(stream);
+
+  // Restore the audio mode which was used before the first communication-
+  // mode stream was created.
+  if (HasNoAudioStreams()) {
+    SetCommunicationAudioModeOn(false);
+  }
 }
 
 AudioOutputStream* AudioManagerAndroid::MakeLinearOutputStream(
     const AudioParameters& params) {
   DCHECK_EQ(AudioParameters::AUDIO_PCM_LINEAR, params.format());
   return new OpenSLESOutputStream(this, params);
 }
 
 AudioOutputStream* AudioManagerAndroid::MakeLowLatencyOutputStream(
     const AudioParameters& params,
@@ skipping 10 matching lines @@
   // needs it.
   DLOG_IF(ERROR, !device_id.empty()) << "Not implemented!";
   DCHECK_EQ(AudioParameters::AUDIO_PCM_LINEAR, params.format());
   return new OpenSLESInputStream(this, params);
 }
 
 AudioInputStream* AudioManagerAndroid::MakeLowLatencyInputStream(
     const AudioParameters& params, const std::string& device_id) {
   DCHECK_EQ(AudioParameters::AUDIO_PCM_LOW_LATENCY, params.format());
   DLOG_IF(ERROR, device_id.empty()) << "Invalid device ID!";
-  // Utilize the device ID to select the correct input device.
+  // Use the device ID to select the correct input device.
   // Note that the input device is always associated with a certain output
   // device, i.e., this selection does also switch the output device.
   // All input and output streams will be affected by the device selection.
-  SetAudioDevice(device_id);
+  if (!SetAudioDevice(device_id)) {
+    LOG(ERROR) << "Unable to select audio device!";
+    return NULL;
+  }
   return new OpenSLESInputStream(this, params);
 }
 
 int AudioManagerAndroid::GetOptimalOutputFrameSize(int sample_rate,
                                                    int channels) {
   if (IsAudioLowLatencySupported()) {
     return GetAudioLowLatencyOutputFrameSize();
   } else {
     return std::max(kDefaultOutputBufferSize,
                     Java_AudioManagerAndroid_getMinOutputFrameSize(
@@ skipping 24 matching lines @@
 
   int user_buffer_size = GetUserBufferSize();
   if (user_buffer_size)
     buffer_size = user_buffer_size;
 
   return AudioParameters(
       AudioParameters::AUDIO_PCM_LOW_LATENCY, channel_layout, input_channels,
       sample_rate, bits_per_sample, buffer_size);
 }
 
+bool AudioManagerAndroid::HasNoAudioStreams() {
+  return output_stream_count() == 0 && input_stream_count() == 0;
+}
+
 // static
 bool AudioManagerAndroid::RegisterAudioManager(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 void AudioManagerAndroid::Init() {
   Java_AudioManagerAndroid_init(
       base::android::AttachCurrentThread(),
       j_audio_manager_.obj());
 }
@@ skipping 14 matching lines @@
 }
 
 void AudioManagerAndroid::DoSetMuteOnAudioThread(bool muted) {
   base::AutoLock lock(streams_lock_);
   for (OutputStreams::iterator it = streams_.begin();
        it != streams_.end(); ++it) {
     (*it)->SetMute(muted);
   }
 }
 
-void AudioManagerAndroid::SetAudioMode(int mode) {
-  Java_AudioManagerAndroid_setMode(
+void AudioManagerAndroid::SetCommunicationAudioModeOn(bool on) {
+  Java_AudioManagerAndroid_setCommunicationAudioModeOn(
       base::android::AttachCurrentThread(),
-      j_audio_manager_.obj(), mode);
+      j_audio_manager_.obj(), on);
 }
 
-void AudioManagerAndroid::SetAudioDevice(const std::string& device_id) {
+bool AudioManagerAndroid::SetAudioDevice(const std::string& device_id) {
   JNIEnv* env = AttachCurrentThread();
 
   // Send the unique device ID to the Java audio manager and make the
   // device switch. Provide an empty string to the Java audio manager
   // if the default device is selected.
   ScopedJavaLocalRef<jstring> j_device_id = ConvertUTF8ToJavaString(
       env,
       device_id == AudioManagerBase::kDefaultDeviceId ?
           std::string() : device_id);
-  Java_AudioManagerAndroid_setDevice(
+  return Java_AudioManagerAndroid_setDevice(
       env, j_audio_manager_.obj(), j_device_id.obj());
 }
 
 int AudioManagerAndroid::GetNativeOutputSampleRate() {
   return Java_AudioManagerAndroid_getNativeOutputSampleRate(
       base::android::AttachCurrentThread(),
       j_audio_manager_.obj());
 }
 
 bool AudioManagerAndroid::IsAudioLowLatencySupported() {
   return Java_AudioManagerAndroid_isAudioLowLatencySupported(
       base::android::AttachCurrentThread(),
       j_audio_manager_.obj());
 }
 
 int AudioManagerAndroid::GetAudioLowLatencyOutputFrameSize() {
   return Java_AudioManagerAndroid_getAudioLowLatencyOutputFrameSize(
       base::android::AttachCurrentThread(),
       j_audio_manager_.obj());
 }
 
 }  // namespace media