modules/audio_device/android/java/src/org/webrtc/voiceengine/WebRtcAudioUtils.java - src - Git at Google

 /*
  *  Copyright (c) 2015 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.
  */

 package org.webrtc.voiceengine;

 import static android.media.AudioManager.MODE_IN_CALL;
 import static android.media.AudioManager.MODE_IN_COMMUNICATION;
 import static android.media.AudioManager.MODE_NORMAL;
 import static android.media.AudioManager.MODE_RINGTONE;

 import android.content.Context;
 import android.content.pm.PackageManager;
 import android.media.AudioDeviceInfo;
 import android.media.AudioManager;
 import android.os.Build;
 import java.lang.Thread;
 import java.util.Arrays;
 import java.util.List;
 import org.webrtc.ContextUtils;
 import org.webrtc.Logging;

 public final class WebRtcAudioUtils {
   private static final String TAG = "WebRtcAudioUtils";

   // List of devices where we have seen issues (e.g. bad audio quality) using
   // the low latency output mode in combination with OpenSL ES.
   // The device name is given by Build.MODEL.
   private static final String[] BLACKLISTED_OPEN_SL_ES_MODELS = new String[] {
       // It is recommended to maintain a list of blacklisted models outside
       // this package and instead call
       // WebRtcAudioManager.setBlacklistDeviceForOpenSLESUsage(true)
       // from the client for devices where OpenSL ES shall be disabled.
   };

   // List of devices where it has been verified that the built-in effect
   // bad and where it makes sense to avoid using it and instead rely on the
   // native WebRTC version instead. The device name is given by Build.MODEL.
   private static final String[] BLACKLISTED_AEC_MODELS = new String[] {
       // It is recommended to maintain a list of blacklisted models outside
       // this package and instead call setWebRtcBasedAcousticEchoCanceler(true)
       // from the client for devices where the built-in AEC shall be disabled.
   };
   private static final String[] BLACKLISTED_NS_MODELS = new String[] {
     // It is recommended to maintain a list of blacklisted models outside
     // this package and instead call setWebRtcBasedNoiseSuppressor(true)
     // from the client for devices where the built-in NS shall be disabled.
   };

   // Use 16kHz as the default sample rate. A higher sample rate might prevent
   // us from supporting communication mode on some older (e.g. ICS) devices.
   private static final int DEFAULT_SAMPLE_RATE_HZ = 16000;
   private static int defaultSampleRateHz = DEFAULT_SAMPLE_RATE_HZ;
   // Set to true if setDefaultSampleRateHz() has been called.
   private static boolean isDefaultSampleRateOverridden;

   // By default, utilize hardware based audio effects for AEC and NS when
   // available.
   private static boolean useWebRtcBasedAcousticEchoCanceler;
   private static boolean useWebRtcBasedNoiseSuppressor;

   // Call these methods if any hardware based effect shall be replaced by a
   // software based version provided by the WebRTC stack instead.
   // TODO(bugs.webrtc.org/8491): Remove NoSynchronizedMethodCheck suppression.
   @SuppressWarnings("NoSynchronizedMethodCheck")
   public static synchronized void setWebRtcBasedAcousticEchoCanceler(boolean enable) {
     useWebRtcBasedAcousticEchoCanceler = enable;
   }

     // TODO(bugs.webrtc.org/8491): Remove NoSynchronizedMethodCheck suppression.
   @SuppressWarnings("NoSynchronizedMethodCheck")
   public static synchronized void setWebRtcBasedNoiseSuppressor(boolean enable) {
     useWebRtcBasedNoiseSuppressor = enable;
   }

   // TODO(bugs.webrtc.org/8491): Remove NoSynchronizedMethodCheck suppression.
   @SuppressWarnings("NoSynchronizedMethodCheck")
   public static synchronized void setWebRtcBasedAutomaticGainControl(boolean enable) {
     // TODO(henrika): deprecated; remove when no longer used by any client.
     Logging.w(TAG, "setWebRtcBasedAutomaticGainControl() is deprecated");
   }

   // TODO(bugs.webrtc.org/8491): Remove NoSynchronizedMethodCheck suppression.
   @SuppressWarnings("NoSynchronizedMethodCheck")
   public static synchronized boolean useWebRtcBasedAcousticEchoCanceler() {
     if (useWebRtcBasedAcousticEchoCanceler) {
       Logging.w(TAG, "Overriding default behavior; now using WebRTC AEC!");
     }
     return useWebRtcBasedAcousticEchoCanceler;
   }

   // TODO(bugs.webrtc.org/8491): Remove NoSynchronizedMethodCheck suppression.
   @SuppressWarnings("NoSynchronizedMethodCheck")
   public static synchronized boolean useWebRtcBasedNoiseSuppressor() {
     if (useWebRtcBasedNoiseSuppressor) {
       Logging.w(TAG, "Overriding default behavior; now using WebRTC NS!");
     }
     return useWebRtcBasedNoiseSuppressor;
   }

   // TODO(henrika): deprecated; remove when no longer used by any client.
   // TODO(bugs.webrtc.org/8491): Remove NoSynchronizedMethodCheck suppression.
   @SuppressWarnings("NoSynchronizedMethodCheck")
   public static synchronized boolean useWebRtcBasedAutomaticGainControl() {
     // Always return true here to avoid trying to use any built-in AGC.
     return true;
   }

   // Returns true if the device supports an audio effect (AEC or NS).
   // Four conditions must be fulfilled if functions are to return true:
   // 1) the platform must support the built-in (HW) effect,
   // 2) explicit use (override) of a WebRTC based version must not be set,
   // 3) the device must not be blacklisted for use of the effect, and
   // 4) the UUID of the effect must be approved (some UUIDs can be excluded).
   public static boolean isAcousticEchoCancelerSupported() {
     return WebRtcAudioEffects.canUseAcousticEchoCanceler();
   }
   public static boolean isNoiseSuppressorSupported() {
     return WebRtcAudioEffects.canUseNoiseSuppressor();
   }
   // TODO(henrika): deprecated; remove when no longer used by any client.
   public static boolean isAutomaticGainControlSupported() {
     // Always return false here to avoid trying to use any built-in AGC.
     return false;
   }

   // Call this method if the default handling of querying the native sample
   // rate shall be overridden. Can be useful on some devices where the
   // available Android APIs are known to return invalid results.
   // TODO(bugs.webrtc.org/8491): Remove NoSynchronizedMethodCheck suppression.
   @SuppressWarnings("NoSynchronizedMethodCheck")
   public static synchronized void setDefaultSampleRateHz(int sampleRateHz) {
     isDefaultSampleRateOverridden = true;
     defaultSampleRateHz = sampleRateHz;
   }

   // TODO(bugs.webrtc.org/8491): Remove NoSynchronizedMethodCheck suppression.
   @SuppressWarnings("NoSynchronizedMethodCheck")
   public static synchronized boolean isDefaultSampleRateOverridden() {
     return isDefaultSampleRateOverridden;
   }

   // TODO(bugs.webrtc.org/8491): Remove NoSynchronizedMethodCheck suppression.
   @SuppressWarnings("NoSynchronizedMethodCheck")
   public static synchronized int getDefaultSampleRateHz() {
     return defaultSampleRateHz;
   }

   public static List<String> getBlackListedModelsForAecUsage() {
     return Arrays.asList(WebRtcAudioUtils.BLACKLISTED_AEC_MODELS);
   }

   public static List<String> getBlackListedModelsForNsUsage() {
     return Arrays.asList(WebRtcAudioUtils.BLACKLISTED_NS_MODELS);
   }

   // Helper method for building a string of thread information.
   public static String getThreadInfo() {
     return "@[name=" + Thread.currentThread().getName() + ", id=" + Thread.currentThread().getId()
         + "]";
   }

   // Returns true if we're running on emulator.
   public static boolean runningOnEmulator() {
     return Build.HARDWARE.equals("goldfish") && Build.BRAND.startsWith("generic_");
   }

   // Returns true if the device is blacklisted for OpenSL ES usage.
   public static boolean deviceIsBlacklistedForOpenSLESUsage() {
     List<String> blackListedModels = Arrays.asList(BLACKLISTED_OPEN_SL_ES_MODELS);
     return blackListedModels.contains(Build.MODEL);
   }

   // Information about the current build, taken from system properties.
   static void logDeviceInfo(String tag) {
     Logging.d(tag, "Android SDK: " + Build.VERSION.SDK_INT + ", "
             + "Release: " + Build.VERSION.RELEASE + ", "
             + "Brand: " + Build.BRAND + ", "
             + "Device: " + Build.DEVICE + ", "
             + "Id: " + Build.ID + ", "
             + "Hardware: " + Build.HARDWARE + ", "
             + "Manufacturer: " + Build.MANUFACTURER + ", "
             + "Model: " + Build.MODEL + ", "
             + "Product: " + Build.PRODUCT);
   }

   // Logs information about the current audio state. The idea is to call this
   // method when errors are detected to log under what conditions the error
   // occurred. Hopefully it will provide clues to what might be the root cause.
   static void logAudioState(String tag) {
     logDeviceInfo(tag);
     final Context context = ContextUtils.getApplicationContext();
     final AudioManager audioManager =
         (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
     logAudioStateBasic(tag, audioManager);
     logAudioStateVolume(tag, audioManager);
     logAudioDeviceInfo(tag, audioManager);
   }

   // Reports basic audio statistics.
   private static void logAudioStateBasic(String tag, AudioManager audioManager) {
     Logging.d(tag, "Audio State: "
             + "audio mode: " + modeToString(audioManager.getMode()) + ", "
             + "has mic: " + hasMicrophone() + ", "
             + "mic muted: " + audioManager.isMicrophoneMute() + ", "
             + "music active: " + audioManager.isMusicActive() + ", "
             + "speakerphone: " + audioManager.isSpeakerphoneOn() + ", "
             + "BT SCO: " + audioManager.isBluetoothScoOn());
   }

   private static boolean isVolumeFixed(AudioManager audioManager) {
     if (Build.VERSION.SDK_INT < 21) {
       return false;
     }
     return audioManager.isVolumeFixed();
   }

   // Adds volume information for all possible stream types.
   private static void logAudioStateVolume(String tag, AudioManager audioManager) {
     final int[] streams = {
         AudioManager.STREAM_VOICE_CALL,
         AudioManager.STREAM_MUSIC,
         AudioManager.STREAM_RING,
         AudioManager.STREAM_ALARM,
         AudioManager.STREAM_NOTIFICATION,
         AudioManager.STREAM_SYSTEM
     };
     Logging.d(tag, "Audio State: ");
     // Some devices may not have volume controls and might use a fixed volume.
     boolean fixedVolume = isVolumeFixed(audioManager);
     Logging.d(tag, "  fixed volume=" + fixedVolume);
     if (!fixedVolume) {
       for (int stream : streams) {
         StringBuilder info = new StringBuilder();
         info.append("  " + streamTypeToString(stream) + ": ");
         info.append("volume=").append(audioManager.getStreamVolume(stream));
         info.append(", max=").append(audioManager.getStreamMaxVolume(stream));
         logIsStreamMute(tag, audioManager, stream, info);
         Logging.d(tag, info.toString());
       }
     }
   }

   private static void logIsStreamMute(
       String tag, AudioManager audioManager, int stream, StringBuilder info) {
     if (Build.VERSION.SDK_INT >= 23) {
       info.append(", muted=").append(audioManager.isStreamMute(stream));
     }
   }

   private static void logAudioDeviceInfo(String tag, AudioManager audioManager) {
     if (Build.VERSION.SDK_INT < 23) {
       return;
     }
     final AudioDeviceInfo[] devices =
         audioManager.getDevices(AudioManager.GET_DEVICES_ALL);
     if (devices.length == 0) {
       return;
     }
     Logging.d(tag, "Audio Devices: ");
     for (AudioDeviceInfo device : devices) {
       StringBuilder info = new StringBuilder();
       info.append("  ").append(deviceTypeToString(device.getType()));
       info.append(device.isSource() ? "(in): " : "(out): ");
       // An empty array indicates that the device supports arbitrary channel counts.
       if (device.getChannelCounts().length > 0) {
         info.append("channels=").append(Arrays.toString(device.getChannelCounts()));
         info.append(", ");
       }
       if (device.getEncodings().length > 0) {
         // Examples: ENCODING_PCM_16BIT = 2, ENCODING_PCM_FLOAT = 4.
         info.append("encodings=").append(Arrays.toString(device.getEncodings()));
         info.append(", ");
       }
       if (device.getSampleRates().length > 0) {
         info.append("sample rates=").append(Arrays.toString(device.getSampleRates()));
         info.append(", ");
       }
       info.append("id=").append(device.getId());
       Logging.d(tag, info.toString());
     }
   }

   // Converts media.AudioManager modes into local string representation.
   static String modeToString(int mode) {
     switch (mode) {
       case MODE_IN_CALL:
         return "MODE_IN_CALL";
       case MODE_IN_COMMUNICATION:
         return "MODE_IN_COMMUNICATION";
       case MODE_NORMAL:
         return "MODE_NORMAL";
       case MODE_RINGTONE:
         return "MODE_RINGTONE";
       default:
         return "MODE_INVALID";
     }
   }

   private static String streamTypeToString(int stream) {
     switch(stream) {
       case AudioManager.STREAM_VOICE_CALL:
         return "STREAM_VOICE_CALL";
       case AudioManager.STREAM_MUSIC:
         return "STREAM_MUSIC";
       case AudioManager.STREAM_RING:
         return "STREAM_RING";
       case AudioManager.STREAM_ALARM:
         return "STREAM_ALARM";
       case AudioManager.STREAM_NOTIFICATION:
         return "STREAM_NOTIFICATION";
       case AudioManager.STREAM_SYSTEM:
         return "STREAM_SYSTEM";
       default:
         return "STREAM_INVALID";
     }
   }

   // Converts AudioDeviceInfo types to local string representation.
   private static String deviceTypeToString(int type) {
     switch (type) {
       case AudioDeviceInfo.TYPE_UNKNOWN:
         return "TYPE_UNKNOWN";
       case AudioDeviceInfo.TYPE_BUILTIN_EARPIECE:
         return "TYPE_BUILTIN_EARPIECE";
       case AudioDeviceInfo.TYPE_BUILTIN_SPEAKER:
         return "TYPE_BUILTIN_SPEAKER";
       case AudioDeviceInfo.TYPE_WIRED_HEADSET:
         return "TYPE_WIRED_HEADSET";
       case AudioDeviceInfo.TYPE_WIRED_HEADPHONES:
         return "TYPE_WIRED_HEADPHONES";
       case AudioDeviceInfo.TYPE_LINE_ANALOG:
         return "TYPE_LINE_ANALOG";
       case AudioDeviceInfo.TYPE_LINE_DIGITAL:
         return "TYPE_LINE_DIGITAL";
       case AudioDeviceInfo.TYPE_BLUETOOTH_SCO:
         return "TYPE_BLUETOOTH_SCO";
       case AudioDeviceInfo.TYPE_BLUETOOTH_A2DP:
         return "TYPE_BLUETOOTH_A2DP";
       case AudioDeviceInfo.TYPE_HDMI:
         return "TYPE_HDMI";
       case AudioDeviceInfo.TYPE_HDMI_ARC:
         return "TYPE_HDMI_ARC";
       case AudioDeviceInfo.TYPE_USB_DEVICE:
         return "TYPE_USB_DEVICE";
       case AudioDeviceInfo.TYPE_USB_ACCESSORY:
         return "TYPE_USB_ACCESSORY";
       case AudioDeviceInfo.TYPE_DOCK:
         return "TYPE_DOCK";
       case AudioDeviceInfo.TYPE_FM:
         return "TYPE_FM";
       case AudioDeviceInfo.TYPE_BUILTIN_MIC:
         return "TYPE_BUILTIN_MIC";
       case AudioDeviceInfo.TYPE_FM_TUNER:
         return "TYPE_FM_TUNER";
       case AudioDeviceInfo.TYPE_TV_TUNER:
         return "TYPE_TV_TUNER";
       case AudioDeviceInfo.TYPE_TELEPHONY:
         return "TYPE_TELEPHONY";
       case AudioDeviceInfo.TYPE_AUX_LINE:
         return "TYPE_AUX_LINE";
       case AudioDeviceInfo.TYPE_IP:
         return "TYPE_IP";
       case AudioDeviceInfo.TYPE_BUS:
         return "TYPE_BUS";
       case AudioDeviceInfo.TYPE_USB_HEADSET:
         return "TYPE_USB_HEADSET";
       default:
         return "TYPE_UNKNOWN";
     }
   }

   // Returns true if the device can record audio via a microphone.
   private static boolean hasMicrophone() {
     return ContextUtils.getApplicationContext().getPackageManager().hasSystemFeature(
         PackageManager.FEATURE_MICROPHONE);
   }
 }
	/*
	* Copyright (c) 2015 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.
	*/

	package org.webrtc.voiceengine;

	import static android.media.AudioManager.MODE_IN_CALL;
	import static android.media.AudioManager.MODE_IN_COMMUNICATION;
	import static android.media.AudioManager.MODE_NORMAL;
	import static android.media.AudioManager.MODE_RINGTONE;

	import android.content.Context;
	import android.content.pm.PackageManager;
	import android.media.AudioDeviceInfo;
	import android.media.AudioManager;
	import android.os.Build;
	import java.lang.Thread;
	import java.util.Arrays;
	import java.util.List;
	import org.webrtc.ContextUtils;
	import org.webrtc.Logging;

	public final class WebRtcAudioUtils {
	private static final String TAG = "WebRtcAudioUtils";

	// List of devices where we have seen issues (e.g. bad audio quality) using
	// the low latency output mode in combination with OpenSL ES.
	// The device name is given by Build.MODEL.
	private static final String[] BLACKLISTED_OPEN_SL_ES_MODELS = new String[] {
	// It is recommended to maintain a list of blacklisted models outside
	// this package and instead call
	// WebRtcAudioManager.setBlacklistDeviceForOpenSLESUsage(true)
	// from the client for devices where OpenSL ES shall be disabled.
	};

	// List of devices where it has been verified that the built-in effect
	// bad and where it makes sense to avoid using it and instead rely on the
	// native WebRTC version instead. The device name is given by Build.MODEL.
	private static final String[] BLACKLISTED_AEC_MODELS = new String[] {
	// It is recommended to maintain a list of blacklisted models outside
	// this package and instead call setWebRtcBasedAcousticEchoCanceler(true)
	// from the client for devices where the built-in AEC shall be disabled.
	};
	private static final String[] BLACKLISTED_NS_MODELS = new String[] {
	// It is recommended to maintain a list of blacklisted models outside
	// this package and instead call setWebRtcBasedNoiseSuppressor(true)
	// from the client for devices where the built-in NS shall be disabled.
	};

	// Use 16kHz as the default sample rate. A higher sample rate might prevent
	// us from supporting communication mode on some older (e.g. ICS) devices.
	private static final int DEFAULT_SAMPLE_RATE_HZ = 16000;
	private static int defaultSampleRateHz = DEFAULT_SAMPLE_RATE_HZ;
	// Set to true if setDefaultSampleRateHz() has been called.
	private static boolean isDefaultSampleRateOverridden;

	// By default, utilize hardware based audio effects for AEC and NS when
	// available.
	private static boolean useWebRtcBasedAcousticEchoCanceler;
	private static boolean useWebRtcBasedNoiseSuppressor;

	// Call these methods if any hardware based effect shall be replaced by a
	// software based version provided by the WebRTC stack instead.
	// TODO(bugs.webrtc.org/8491): Remove NoSynchronizedMethodCheck suppression.
	@SuppressWarnings("NoSynchronizedMethodCheck")
	public static synchronized void setWebRtcBasedAcousticEchoCanceler(boolean enable) {
	useWebRtcBasedAcousticEchoCanceler = enable;
	}

	// TODO(bugs.webrtc.org/8491): Remove NoSynchronizedMethodCheck suppression.
	@SuppressWarnings("NoSynchronizedMethodCheck")
	public static synchronized void setWebRtcBasedNoiseSuppressor(boolean enable) {
	useWebRtcBasedNoiseSuppressor = enable;
	}

	// TODO(bugs.webrtc.org/8491): Remove NoSynchronizedMethodCheck suppression.
	@SuppressWarnings("NoSynchronizedMethodCheck")
	public static synchronized void setWebRtcBasedAutomaticGainControl(boolean enable) {
	// TODO(henrika): deprecated; remove when no longer used by any client.
	Logging.w(TAG, "setWebRtcBasedAutomaticGainControl() is deprecated");
	}

	// TODO(bugs.webrtc.org/8491): Remove NoSynchronizedMethodCheck suppression.
	@SuppressWarnings("NoSynchronizedMethodCheck")
	public static synchronized boolean useWebRtcBasedAcousticEchoCanceler() {
	if (useWebRtcBasedAcousticEchoCanceler) {
	Logging.w(TAG, "Overriding default behavior; now using WebRTC AEC!");
	}
	return useWebRtcBasedAcousticEchoCanceler;
	}

	// TODO(bugs.webrtc.org/8491): Remove NoSynchronizedMethodCheck suppression.
	@SuppressWarnings("NoSynchronizedMethodCheck")
	public static synchronized boolean useWebRtcBasedNoiseSuppressor() {
	if (useWebRtcBasedNoiseSuppressor) {
	Logging.w(TAG, "Overriding default behavior; now using WebRTC NS!");
	}
	return useWebRtcBasedNoiseSuppressor;
	}

	// TODO(henrika): deprecated; remove when no longer used by any client.
	// TODO(bugs.webrtc.org/8491): Remove NoSynchronizedMethodCheck suppression.
	@SuppressWarnings("NoSynchronizedMethodCheck")
	public static synchronized boolean useWebRtcBasedAutomaticGainControl() {
	// Always return true here to avoid trying to use any built-in AGC.
	return true;
	}

	// Returns true if the device supports an audio effect (AEC or NS).
	// Four conditions must be fulfilled if functions are to return true:
	// 1) the platform must support the built-in (HW) effect,
	// 2) explicit use (override) of a WebRTC based version must not be set,
	// 3) the device must not be blacklisted for use of the effect, and
	// 4) the UUID of the effect must be approved (some UUIDs can be excluded).
	public static boolean isAcousticEchoCancelerSupported() {
	return WebRtcAudioEffects.canUseAcousticEchoCanceler();
	}
	public static boolean isNoiseSuppressorSupported() {
	return WebRtcAudioEffects.canUseNoiseSuppressor();
	}
	// TODO(henrika): deprecated; remove when no longer used by any client.
	public static boolean isAutomaticGainControlSupported() {
	// Always return false here to avoid trying to use any built-in AGC.
	return false;
	}

	// Call this method if the default handling of querying the native sample
	// rate shall be overridden. Can be useful on some devices where the
	// available Android APIs are known to return invalid results.
	// TODO(bugs.webrtc.org/8491): Remove NoSynchronizedMethodCheck suppression.
	@SuppressWarnings("NoSynchronizedMethodCheck")
	public static synchronized void setDefaultSampleRateHz(int sampleRateHz) {
	isDefaultSampleRateOverridden = true;
	defaultSampleRateHz = sampleRateHz;
	}

	// TODO(bugs.webrtc.org/8491): Remove NoSynchronizedMethodCheck suppression.
	@SuppressWarnings("NoSynchronizedMethodCheck")
	public static synchronized boolean isDefaultSampleRateOverridden() {
	return isDefaultSampleRateOverridden;
	}

	// TODO(bugs.webrtc.org/8491): Remove NoSynchronizedMethodCheck suppression.
	@SuppressWarnings("NoSynchronizedMethodCheck")
	public static synchronized int getDefaultSampleRateHz() {
	return defaultSampleRateHz;
	}

	public static List<String> getBlackListedModelsForAecUsage() {
	return Arrays.asList(WebRtcAudioUtils.BLACKLISTED_AEC_MODELS);
	}

	public static List<String> getBlackListedModelsForNsUsage() {
	return Arrays.asList(WebRtcAudioUtils.BLACKLISTED_NS_MODELS);
	}

	// Helper method for building a string of thread information.
	public static String getThreadInfo() {
	return "@[name=" + Thread.currentThread().getName() + ", id=" + Thread.currentThread().getId()
	+ "]";
	}

	// Returns true if we're running on emulator.
	public static boolean runningOnEmulator() {
	return Build.HARDWARE.equals("goldfish") && Build.BRAND.startsWith("generic_");
	}

	// Returns true if the device is blacklisted for OpenSL ES usage.
	public static boolean deviceIsBlacklistedForOpenSLESUsage() {
	List<String> blackListedModels = Arrays.asList(BLACKLISTED_OPEN_SL_ES_MODELS);
	return blackListedModels.contains(Build.MODEL);
	}

	// Information about the current build, taken from system properties.
	static void logDeviceInfo(String tag) {
	Logging.d(tag, "Android SDK: " + Build.VERSION.SDK_INT + ", "
	+ "Release: " + Build.VERSION.RELEASE + ", "
	+ "Brand: " + Build.BRAND + ", "
	+ "Device: " + Build.DEVICE + ", "
	+ "Id: " + Build.ID + ", "
	+ "Hardware: " + Build.HARDWARE + ", "
	+ "Manufacturer: " + Build.MANUFACTURER + ", "
	+ "Model: " + Build.MODEL + ", "
	+ "Product: " + Build.PRODUCT);
	}

	// Logs information about the current audio state. The idea is to call this
	// method when errors are detected to log under what conditions the error
	// occurred. Hopefully it will provide clues to what might be the root cause.
	static void logAudioState(String tag) {
	logDeviceInfo(tag);
	final Context context = ContextUtils.getApplicationContext();
	final AudioManager audioManager =
	(AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
	logAudioStateBasic(tag, audioManager);
	logAudioStateVolume(tag, audioManager);
	logAudioDeviceInfo(tag, audioManager);
	}

	// Reports basic audio statistics.
	private static void logAudioStateBasic(String tag, AudioManager audioManager) {
	Logging.d(tag, "Audio State: "
	+ "audio mode: " + modeToString(audioManager.getMode()) + ", "
	+ "has mic: " + hasMicrophone() + ", "
	+ "mic muted: " + audioManager.isMicrophoneMute() + ", "
	+ "music active: " + audioManager.isMusicActive() + ", "
	+ "speakerphone: " + audioManager.isSpeakerphoneOn() + ", "
	+ "BT SCO: " + audioManager.isBluetoothScoOn());
	}

	private static boolean isVolumeFixed(AudioManager audioManager) {
	if (Build.VERSION.SDK_INT < 21) {
	return false;
	}
	return audioManager.isVolumeFixed();
	}

	// Adds volume information for all possible stream types.
	private static void logAudioStateVolume(String tag, AudioManager audioManager) {
	final int[] streams = {
	AudioManager.STREAM_VOICE_CALL,
	AudioManager.STREAM_MUSIC,
	AudioManager.STREAM_RING,
	AudioManager.STREAM_ALARM,
	AudioManager.STREAM_NOTIFICATION,
	AudioManager.STREAM_SYSTEM
	};
	Logging.d(tag, "Audio State: ");
	// Some devices may not have volume controls and might use a fixed volume.
	boolean fixedVolume = isVolumeFixed(audioManager);
	Logging.d(tag, " fixed volume=" + fixedVolume);
	if (!fixedVolume) {
	for (int stream : streams) {
	StringBuilder info = new StringBuilder();
	info.append(" " + streamTypeToString(stream) + ": ");
	info.append("volume=").append(audioManager.getStreamVolume(stream));
	info.append(", max=").append(audioManager.getStreamMaxVolume(stream));
	logIsStreamMute(tag, audioManager, stream, info);
	Logging.d(tag, info.toString());
	}
	}
	}

	private static void logIsStreamMute(
	String tag, AudioManager audioManager, int stream, StringBuilder info) {
	if (Build.VERSION.SDK_INT >= 23) {
	info.append(", muted=").append(audioManager.isStreamMute(stream));
	}
	}

	private static void logAudioDeviceInfo(String tag, AudioManager audioManager) {
	if (Build.VERSION.SDK_INT < 23) {
	return;
	}
	final AudioDeviceInfo[] devices =
	audioManager.getDevices(AudioManager.GET_DEVICES_ALL);
	if (devices.length == 0) {
	return;
	}
	Logging.d(tag, "Audio Devices: ");
	for (AudioDeviceInfo device : devices) {
	StringBuilder info = new StringBuilder();
	info.append(" ").append(deviceTypeToString(device.getType()));
	info.append(device.isSource() ? "(in): " : "(out): ");
	// An empty array indicates that the device supports arbitrary channel counts.
	if (device.getChannelCounts().length > 0) {
	info.append("channels=").append(Arrays.toString(device.getChannelCounts()));
	info.append(", ");
	}
	if (device.getEncodings().length > 0) {
	// Examples: ENCODING_PCM_16BIT = 2, ENCODING_PCM_FLOAT = 4.
	info.append("encodings=").append(Arrays.toString(device.getEncodings()));
	info.append(", ");
	}
	if (device.getSampleRates().length > 0) {
	info.append("sample rates=").append(Arrays.toString(device.getSampleRates()));
	info.append(", ");
	}
	info.append("id=").append(device.getId());
	Logging.d(tag, info.toString());
	}
	}

	// Converts media.AudioManager modes into local string representation.
	static String modeToString(int mode) {
	switch (mode) {
	case MODE_IN_CALL:
	return "MODE_IN_CALL";
	case MODE_IN_COMMUNICATION:
	return "MODE_IN_COMMUNICATION";
	case MODE_NORMAL:
	return "MODE_NORMAL";
	case MODE_RINGTONE:
	return "MODE_RINGTONE";
	default:
	return "MODE_INVALID";
	}
	}

	private static String streamTypeToString(int stream) {
	switch(stream) {
	case AudioManager.STREAM_VOICE_CALL:
	return "STREAM_VOICE_CALL";
	case AudioManager.STREAM_MUSIC:
	return "STREAM_MUSIC";
	case AudioManager.STREAM_RING:
	return "STREAM_RING";
	case AudioManager.STREAM_ALARM:
	return "STREAM_ALARM";
	case AudioManager.STREAM_NOTIFICATION:
	return "STREAM_NOTIFICATION";
	case AudioManager.STREAM_SYSTEM:
	return "STREAM_SYSTEM";
	default:
	return "STREAM_INVALID";
	}
	}

	// Converts AudioDeviceInfo types to local string representation.
	private static String deviceTypeToString(int type) {
	switch (type) {
	case AudioDeviceInfo.TYPE_UNKNOWN:
	return "TYPE_UNKNOWN";
	case AudioDeviceInfo.TYPE_BUILTIN_EARPIECE:
	return "TYPE_BUILTIN_EARPIECE";
	case AudioDeviceInfo.TYPE_BUILTIN_SPEAKER:
	return "TYPE_BUILTIN_SPEAKER";
	case AudioDeviceInfo.TYPE_WIRED_HEADSET:
	return "TYPE_WIRED_HEADSET";
	case AudioDeviceInfo.TYPE_WIRED_HEADPHONES:
	return "TYPE_WIRED_HEADPHONES";
	case AudioDeviceInfo.TYPE_LINE_ANALOG:
	return "TYPE_LINE_ANALOG";
	case AudioDeviceInfo.TYPE_LINE_DIGITAL:
	return "TYPE_LINE_DIGITAL";
	case AudioDeviceInfo.TYPE_BLUETOOTH_SCO:
	return "TYPE_BLUETOOTH_SCO";
	case AudioDeviceInfo.TYPE_BLUETOOTH_A2DP:
	return "TYPE_BLUETOOTH_A2DP";
	case AudioDeviceInfo.TYPE_HDMI:
	return "TYPE_HDMI";
	case AudioDeviceInfo.TYPE_HDMI_ARC:
	return "TYPE_HDMI_ARC";
	case AudioDeviceInfo.TYPE_USB_DEVICE:
	return "TYPE_USB_DEVICE";
	case AudioDeviceInfo.TYPE_USB_ACCESSORY:
	return "TYPE_USB_ACCESSORY";
	case AudioDeviceInfo.TYPE_DOCK:
	return "TYPE_DOCK";
	case AudioDeviceInfo.TYPE_FM:
	return "TYPE_FM";
	case AudioDeviceInfo.TYPE_BUILTIN_MIC:
	return "TYPE_BUILTIN_MIC";
	case AudioDeviceInfo.TYPE_FM_TUNER:
	return "TYPE_FM_TUNER";
	case AudioDeviceInfo.TYPE_TV_TUNER:
	return "TYPE_TV_TUNER";
	case AudioDeviceInfo.TYPE_TELEPHONY:
	return "TYPE_TELEPHONY";
	case AudioDeviceInfo.TYPE_AUX_LINE:
	return "TYPE_AUX_LINE";
	case AudioDeviceInfo.TYPE_IP:
	return "TYPE_IP";
	case AudioDeviceInfo.TYPE_BUS:
	return "TYPE_BUS";
	case AudioDeviceInfo.TYPE_USB_HEADSET:
	return "TYPE_USB_HEADSET";
	default:
	return "TYPE_UNKNOWN";
	}
	}

	// Returns true if the device can record audio via a microphone.
	private static boolean hasMicrophone() {
	return ContextUtils.getApplicationContext().getPackageManager().hasSystemFeature(
	PackageManager.FEATURE_MICROPHONE);
	}
	}