Android AudioSystem

一、AudioSystem介绍

AudioSystem是Android系统中提供的一个API，用于管理音频系统的参数和状态。它提供了一组静态方法，允许开发者查询和设置音频参数、获取系统状态、控制音频焦点等。AudioSystem是Android系统中标准的音频API之一，底层实现与AudioService密切相关。

AudioSystem包括了很多函数接口，其中最常用的函数为setMasterVolume和getMasterVolume，其中，setMasterVolume函数用于设置全局的音量，该函数接受一个浮点类型的值。除此之外，AudioSystem还提供了其他一些函数接口，如获取音频设备的状态、管理音频特效等。

在Android Framework层，有很多类会使用AudioSystem提供的静态方法，下面列举一些常见的类：

1、AudioManager：Android系统中管理音频相关参数的类，其内部调用了AudioSystem的很多静态方法，比如setMasterVolume和getMasterVolume。

2、AudioTrack：音频播放类，内部使用了AudioSystem的一些静态方法，如获取音频设备的buffer大小等。

3、AudioRecord：音频录制类，内部使用了AudioSystem的一些静态方法，如获取音频设备的buffer大小等。

4、AudioPolicyManager：音频策略管理的类，可以理解为AudioService的一部分，它在处理音频策略时，需要使用一些AudioSystem提供的静态方法，如获取音频设备的状态等。

AudioSystem由JAVA代码、JNI代码、C++代码组成：

AudioSystem代码位于：

frameworks/base/service/java/com/android/server/audio/AudioSystem.java

frameworks/base/core/jni/android_media_AudioSystem.cpp

frameworks/base/core/jni/android_media_AudioSystem.h

frameworks/av/media/libaudioclient/AudioSystem.cpp

frameworks/av/media/libaudioclient/include/media/AudioSystem.h

AudioSystem的定义：

public class AudioSystem {}
class AudioSystem{}

二、AudioSystem方法和常量

AudioSystem方法

• static void setErrorCallback(ErrorCallback cb)：设置错误回调

• static void setDynamicPolicyCallback(DynamicPolicyCallback cb)：设置一个回调函数来动态更新设备的音频策略

• static void setRecordingCallback(AudioRecordingCallback cb)：设置一个回调函数来监听录音状体和录音数据

• static boolean isSingleVolume(Context context)：检测设备是否只有一个音量控制

• static int setStreamVolumeIndexAS(int stream, int index, int device)：设置Stream音量

• static int getValueForVibrateSetting(int existingValue, int vibrateType, int vibrateSetting) ：

• static int getDefaultStreamVolume(int streamType)：获取默认Srteam音量

• static String streamToString(int stream) ：Stream转为String

• static native int setParameters(String keyValuePairs)：设置音频参数

• static native String getParameters(String keys)：获取音频参数

• static native int setDeviceConnectionState(int device, int state, String device_address, String device_name, int codecFormat)：设置设备连接状态

• static native int getDeviceConnectionState(int device, String device_address)：获取设备连接状态

• static native int handleDeviceConfigChange(int device, String device_address, String device_name, int codecFormat)：设备设置变更处理

• static native int setPhoneState(int state)：设置电话状态

• static native int setForceUse(int usage, int config)：设置设备音频的使用方案

• static native int getForceUse(int usage)：获取设备音频的使用方案

• static native int initStreamVolume(int stream, int indexMin, int indexMax)：初始化Stream音量

• static native int setStreamVolumeIndex(int stream, int index, int device)：设置Stream音量

• static native int getStreamVolumeIndex(int stream, int device)：获取Stream音量

• static native int setVolumeIndexForAttributes(@NonNull AudioAttributes attributes, int index, int device)：设置音量

• static native int getVolumeIndexForAttributes(@NonNull AudioAttributes attributes, int device)：获取音量

• static native int getMinVolumeIndexForAttributes(@NonNull AudioAttributes attributes)：获取最小音量

• static native int getMaxVolumeIndexForAttributes(@NonNull AudioAttributes attributes)：获取最大音量

• static native int setMasterVolume(float value)：设置主音量

• static native float getMasterVolume()：获取主音量

• static native int setMasterMute(boolean mute)：设置主音量静音

• static native boolean getMasterMute();：获取主音量静音

• static native int getDevicesForStream(int stream)：获取设备

• static native int setMasterMono(boolean mono)：设置主单声道

• static native boolean getMasterMono()：获取主单声道

• static native int setRttEnabled(boolean enabled)：使能RTT

• static native int getPrimaryOutputSamplingRate()：设置主输出采样率

• static native int getPrimaryOutputFrameCount()：获取音频输出设备的缓冲帧大小

• static native int getOutputLatency(int stream)：获取音频输出设备的音频延迟

• static native int setLowRamDevice(boolean isLowRamDevice, long totalMemory)：

• static native int checkAudioFlinger()：检测AudioFlinger

• static native int listAudioPorts(ArrayList<AudioPort> ports, int[] generation)：

• static native int createAudioPatch(AudioPatch[] patch, AudioPortConfig[] sources, AudioPortConfig[] sinks)：创建Audio Patch

• static native int releaseAudioPatch(AudioPatch patch)：释放Audio Patch

• static native int listAudioPatches(ArrayList<AudioPatch> patches, int[] generation)：获取当前音频设备的连接状态并返回音频连接列表

• static native int setAudioPortConfig(AudioPortConfig config)：设置音频端口的配置参数

• static native int startAudioSource(AudioPortConfig config, AudioAttributes audioAttributes)：开始Audio Source

• static native int stopAudioSource(int handle)：停止Audio Source

• static native int getAudioHwSyncForSession(int sessionId)：获取Audio硬件Sync

• static native int registerPolicyMixes(ArrayList<AudioMix> mixes, boolean register)：注册音频策略混合器

• static native int setUidDeviceAffinities(int uid, @NonNull int[] types, @NonNull String[] addresses)：设置指定应用程序的音频设备亲和性

• static native int removeUidDeviceAffinities(int uid)：删除指定应用的音频设备亲和性

• static native int systemReady()：Audio系统Ready

• static native float getStreamVolumeDB(int stream, int index, int device)：获取Stream音量DB值

• static native int setAllowedCapturePolicy(int uid, int flags)：设置音频捕获策略限制

• static native int getMicrophones(ArrayList<MicrophoneInfo> microphonesInfo)：获取当前系统可用的麦克风列表

• static native int getSurroundFormats(Map<Integer, Boolean> surroundFormats, boolean reported)：获取当前系统支持的环绕声格式列表

• static native int getHwOffloadEncodingFormatsSupportedForA2DP(ArrayList<Integer> formatList)：

• static native int setSurroundFormatEnabled(int audioFormat, boolean enabled)：启用或禁用特定环绕声格式

• static native int setAssistantUid(int uid)：

• static native boolean isHapticPlaybackSupported()：

AudioSystem常量

AUDIO_STREAM

• public static final int STREAM_DEFAULT = -1;

• public static final int STREAM_VOICE_CALL = 0;

• public static final int STREAM_SYSTEM = 1;

• public static final int STREAM_RING = 2;

• public static final int STREAM_MUSIC = 3;

• public static final int STREAM_ALARM = 4;

• public static final int STREAM_NOTIFICATION = 5;

• public static final int STREAM_BLUETOOTH_SCO = 6;

• public static final int STREAM_SYSTEM_ENFORCED = 7;

• public static final int STREAM_DTMF = 8;

• public static final int STREAM_TTS = 9;

• public static final int STREAM_ACCESSIBILITY = 10;

AUDIO_FORCE

• public static final int FORCE_NONE = 0;

• public static final int FORCE_SPEAKER = 1;

• public static final int FORCE_HEADPHONES = 2;

• public static final int FORCE_BT_SCO = 3;

• public static final int FORCE_BT_A2DP = 4;

• public static final int FORCE_WIRED_ACCESSORY = 5;

• public static final int FORCE_BT_CAR_DOCK = 6;

• public static final int FORCE_BT_DESK_DOCK = 7;

• public static final int FORCE_ANALOG_DOCK = 8;

• public static final int FORCE_DIGITAL_DOCK = 9;

• public static final int FORCE_NO_BT_A2DP = 10;

• public static final int FORCE_SYSTEM_ENFORCED = 11;

• public static final int FORCE_HDMI_SYSTEM_AUDIO_ENFORCED = 12;

• public static final int FORCE_ENCODED_SURROUND_NEVER = 13;

• public static final int FORCE_ENCODED_SURROUND_ALWAYS = 14;

• public static final int FORCE_ENCODED_SURROUND_MANUAL = 15;

• public static final int NUM_FORCE_CONFIG = 16;

DEVICE_OUT

• public static final int DEVICE_NONE = 0x0;

• public static final int DEVICE_BIT_IN = 0x80000000;

• public static final int DEVICE_BIT_DEFAULT = 0x40000000;

• public static final int DEVICE_OUT_EARPIECE = 0x1;

• public static final int DEVICE_OUT_SPEAKER = 0x2;

• public static final int DEVICE_OUT_WIRED_HEADSET = 0x4;

• public static final int DEVICE_OUT_WIRED_HEADPHONE = 0x8;

• public static final int DEVICE_OUT_BLUETOOTH_SCO = 0x10;

• public static final int DEVICE_OUT_BLUETOOTH_SCO_HEADSET = 0x20;

• public static final int DEVICE_OUT_BLUETOOTH_SCO_CARKIT = 0x40;

• public static final int DEVICE_OUT_BLUETOOTH_A2DP = 0x80;

• public static final int DEVICE_OUT_BLUETOOTH_A2DP_HEADPHONES = 0x100;

• public static final int DEVICE_OUT_BLUETOOTH_A2DP_SPEAKER = 0x200;

• public static final int DEVICE_OUT_AUX_DIGITAL = 0x400;

• public static final int DEVICE_OUT_HDMI = DEVICE_OUT_AUX_DIGITAL;

• public static final int DEVICE_OUT_ANLG_DOCK_HEADSET = 0x800;

• public static final int DEVICE_OUT_DGTL_DOCK_HEADSET = 0x1000;

• public static final int DEVICE_OUT_USB_ACCESSORY = 0x2000;

• public static final int DEVICE_OUT_USB_DEVICE = 0x4000;

• public static final int DEVICE_OUT_REMOTE_SUBMIX = 0x8000;

• public static final int DEVICE_OUT_TELEPHONY_TX = 0x10000;

• public static final int DEVICE_OUT_LINE = 0x20000;

• public static final int DEVICE_OUT_HDMI_ARC = 0x40000;

• public static final int DEVICE_OUT_SPDIF = 0x80000;

• public static final int DEVICE_OUT_FM = 0x100000;

• public static final int DEVICE_OUT_AUX_LINE = 0x200000;

• public static final int DEVICE_OUT_SPEAKER_SAFE = 0x400000;

• public static final int DEVICE_OUT_IP = 0x800000;

• public static final int DEVICE_OUT_BUS = 0x1000000;

• public static final int DEVICE_OUT_PROXY = 0x2000000;

• public static final int DEVICE_OUT_USB_HEADSET = 0x4000000;

• public static final int DEVICE_OUT_HEARING_AID = 0x8000000;

• public static final int DEVICE_OUT_DEFAULT = DEVICE_BIT_DEFAULT;

DEVICE_IN

• public static final int DEVICE_IN_COMMUNICATION = DEVICE_BIT_IN | 0x1;

• public static final int DEVICE_IN_AMBIENT = DEVICE_BIT_IN | 0x2;

• public static final int DEVICE_IN_BUILTIN_MIC = DEVICE_BIT_IN | 0x4;

• public static final int DEVICE_IN_BLUETOOTH_SCO_HEADSET = DEVICE_BIT_IN | 0x8;

• public static final int DEVICE_IN_WIRED_HEADSET = DEVICE_BIT_IN | 0x10;

• public static final int DEVICE_IN_AUX_DIGITAL = DEVICE_BIT_IN | 0x20;

• public static final int DEVICE_IN_HDMI = DEVICE_IN_AUX_DIGITAL;

• public static final int DEVICE_IN_VOICE_CALL = DEVICE_BIT_IN | 0x40;

• public static final int DEVICE_IN_TELEPHONY_RX = DEVICE_IN_VOICE_CALL;

• public static final int DEVICE_IN_BACK_MIC = DEVICE_BIT_IN | 0x80;

• public static final int DEVICE_IN_REMOTE_SUBMIX = DEVICE_BIT_IN | 0x100;

• public static final int DEVICE_IN_ANLG_DOCK_HEADSET = DEVICE_BIT_IN | 0x200;

• public static final int DEVICE_IN_DGTL_DOCK_HEADSET = DEVICE_BIT_IN | 0x400;

• public static final int DEVICE_IN_USB_ACCESSORY = DEVICE_BIT_IN | 0x800;

• public static final int DEVICE_IN_USB_DEVICE = DEVICE_BIT_IN | 0x1000;

• public static final int DEVICE_IN_FM_TUNER = DEVICE_BIT_IN | 0x2000;

• public static final int DEVICE_IN_TV_TUNER = DEVICE_BIT_IN | 0x4000;

• public static final int DEVICE_IN_LINE = DEVICE_BIT_IN | 0x8000;

• public static final int DEVICE_IN_SPDIF = DEVICE_BIT_IN | 0x10000;

• public static final int DEVICE_IN_BLUETOOTH_A2DP = DEVICE_BIT_IN | 0x20000;

• public static final int DEVICE_IN_LOOPBACK = DEVICE_BIT_IN | 0x40000;

• public static final int DEVICE_IN_IP = DEVICE_BIT_IN | 0x80000;

• public static final int DEVICE_IN_BUS = DEVICE_BIT_IN | 0x100000;

• public static final int DEVICE_IN_PROXY = DEVICE_BIT_IN | 0x1000000;

• public static final int DEVICE_IN_USB_HEADSET = DEVICE_BIT_IN | 0x2000000;

• public static final int DEVICE_IN_BLUETOOTH_BLE = DEVICE_BIT_IN | 0x4000000;

• public static final int DEVICE_IN_HDMI_ARC = DEVICE_BIT_IN | 0x8000000;

• public static final int DEVICE_IN_ECHO_REFERENCE = DEVICE_BIT_IN | 0x10000000;

• public static final int DEVICE_IN_DEFAULT = DEVICE_BIT_IN | DEVICE_BIT_DEFAULT;

AUDIO_FORMAT

• public static final int AUDIO_FORMAT_INVALID = 0xFFFFFFFF;

• public static final int AUDIO_FORMAT_DEFAULT = 0;

• public static final int AUDIO_FORMAT_AAC = 0x04000000;

• public static final int AUDIO_FORMAT_SBC = 0x1F000000;

• public static final int AUDIO_FORMAT_APTX = 0x20000000;

• public static final int AUDIO_FORMAT_APTX_HD = 0x21000000;

• public static final int AUDIO_FORMAT_LDAC = 0x23000000;