webrtc/modules/audio_device/android/java/src/org/webrtc/voiceengine/AudioManagerAndroid.java

/*
 *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

// The functions in this file are called from native code. They can still be
// accessed even though they are declared private.

package org.webrtc.voiceengine;

import android.content.Context;
import android.content.pm.PackageManager;
import android.media.AudioManager;

class AudioManagerAndroid {
  // Most of Google lead devices use 44.1K as the default sampling rate, 44.1K
  // is also widely used on other android devices.
  private static final int DEFAULT_SAMPLING_RATE = 44100;
  // Randomly picked up frame size which is close to return value on N4.
  // Return this default value when
  // getProperty(PROPERTY_OUTPUT_FRAMES_PER_BUFFER) fails.
  private static final int DEFAULT_FRAMES_PER_BUFFER = 256;

  private int mNativeOutputSampleRate;
  private boolean mAudioLowLatencySupported;
  private int mAudioLowLatencyOutputFrameSize;


  @SuppressWarnings("unused")
  private AudioManagerAndroid(Context context) {
    AudioManager audioManager = (AudioManager)
        context.getSystemService(Context.AUDIO_SERVICE);

    mNativeOutputSampleRate = DEFAULT_SAMPLING_RATE;
    mAudioLowLatencyOutputFrameSize = DEFAULT_FRAMES_PER_BUFFER;
    if (android.os.Build.VERSION.SDK_INT >=
        android.os.Build.VERSION_CODES.JELLY_BEAN_MR1) {
      String sampleRateString = audioManager.getProperty(
          AudioManager.PROPERTY_OUTPUT_SAMPLE_RATE);
      if (sampleRateString != null) {
        mNativeOutputSampleRate = Integer.parseInt(sampleRateString);
      }
      String framesPerBuffer = audioManager.getProperty(
          AudioManager.PROPERTY_OUTPUT_FRAMES_PER_BUFFER);
      if (framesPerBuffer != null) {
          mAudioLowLatencyOutputFrameSize = Integer.parseInt(framesPerBuffer);
      }
    }
    mAudioLowLatencySupported = context.getPackageManager().hasSystemFeature(
        PackageManager.FEATURE_AUDIO_LOW_LATENCY);
  }

    @SuppressWarnings("unused")
    private int getNativeOutputSampleRate() {
      return mNativeOutputSampleRate;
    }

    @SuppressWarnings("unused")
    private boolean isAudioLowLatencySupported() {
        return mAudioLowLatencySupported;
    }

    @SuppressWarnings("unused")
    private int getAudioLowLatencyOutputFrameSize() {
        return mAudioLowLatencyOutputFrameSize;
    }
}