Set default sampling rate to 44100 and query the native output sampling rate.

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/logging.h"
 #include "jni/AudioManagerAndroid_jni.h"
 #include "media/audio/android/opensles_input.h"
 #include "media/audio/android/opensles_output.h"
@@ skipping 38 matching lines @@
 
 void AudioManagerAndroid::GetAudioInputDeviceNames(
     media::AudioDeviceNames* device_names) {
   DCHECK(device_names->empty());
   device_names->push_front(
       media::AudioDeviceName(kDefaultDeviceName, kDefaultDeviceId));
 }
 
 AudioParameters AudioManagerAndroid::GetInputStreamParameters(
     const std::string& device_id) {
-  // TODO(xians): figure out the right input sample rate and buffer size to
-  // achieve the best audio performance for Android devices.
+  // TODO(leozwang): Android defines the minimal buffer size requirment
+  // we should use it.
+  static const int kDefaultBufferSize = 1024;
   // TODO(xians): query the native channel layout for the specific device.
-  static const int kDefaultSampleRate = 16000;
-  static const int kDefaultBufferSize = 1024;
   return AudioParameters(
       AudioParameters::AUDIO_PCM_LOW_LATENCY, CHANNEL_LAYOUT_STEREO,
-      kDefaultSampleRate, 16, kDefaultBufferSize);
+      GetNativeOutputSampleRate(), 16, kDefaultBufferSize);

[Raymond Toy (Google), 2013/05/15 23:19:46]

Is it right to set the input sample rate to the output sample rate?

[leozwang1, 2013/05/16 01:11:55]

There is no api to query input sampling rate now. It's the best guess that SoC
will have same sampling rate for both input and output, probably it's true on
most of google lead devices.

 }
 
 AudioOutputStream* AudioManagerAndroid::MakeAudioOutputStream(
     const AudioParameters& params) {
   AudioOutputStream* stream =
     AudioManagerBase::MakeAudioOutputStream(params);
   if (stream && output_stream_count() == 1)
     RegisterHeadsetReceiver();
   return stream;
 }
@@ skipping 38 matching lines @@
 }
 
 AudioInputStream* AudioManagerAndroid::MakeLowLatencyInputStream(
     const AudioParameters& params, const std::string& device_id) {
   DCHECK_EQ(AudioParameters::AUDIO_PCM_LOW_LATENCY, params.format());
   return new OpenSLESInputStream(this, params);
 }
 
 AudioParameters AudioManagerAndroid::GetPreferredOutputStreamParameters(
     const AudioParameters& input_params) {
-  // TODO(xians): figure out the right output sample rate and buffer size to
-  // achieve the best audio performance for Android devices.
-  static const int kDefaultSampleRate = 44100;
+  // TODO(leozwang): Android defines the minimal buffer size requirment
+  // we should use it.
   static const int kDefaultBufferSize = 2048;
 
   ChannelLayout channel_layout = CHANNEL_LAYOUT_STEREO;
-  int sample_rate = kDefaultSampleRate;
+  int sample_rate = GetNativeOutputSampleRate();
   int buffer_size = kDefaultBufferSize;
   int bits_per_sample = 16;
   int input_channels = 0;
   if (input_params.IsValid()) {
     // Use the client's input parameters if they are valid.
     sample_rate = input_params.sample_rate();
     bits_per_sample = input_params.bits_per_sample();
     channel_layout = input_params.channel_layout();
     input_channels = input_params.input_channels();
 
-    // TODO(leozwang): Android defines the minimal buffer size requirment
-    // we should follow it. From Android 4.1, a new audio low latency api
-    // set was introduced and is under development, we want to take advantage
-    // of it.
     buffer_size = std::min(buffer_size, input_params.frames_per_buffer());
   }
 
   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);
@@ skipping 15 matching lines @@
       base::android::AttachCurrentThread(),
       j_audio_manager_.obj());
 }
 
 void AudioManagerAndroid::UnregisterHeadsetReceiver() {
   Java_AudioManagerAndroid_unregisterHeadsetReceiver(
       base::android::AttachCurrentThread(),
       j_audio_manager_.obj());
 }
 
+int AudioManagerAndroid::GetNativeOutputSampleRate() {
+  return Java_AudioManagerAndroid_getNativeOutputSampleRate(
+      base::android::AttachCurrentThread(),
+      j_audio_manager_.obj());
+}
+
 }  // namespace media