1.音频录制(pcm录制)
安卓中可使用AudioRecord进行音频录制,录制的结果是pcm文件,也就是音频裸数据(裸流)。可调用AudioRecord.startRecording进行录制,不过使用前需要初始化AudioRecord。
Java层构造AudioRecord,参数有音频源,采样率,声道数,采样位深,缓冲区大小(通过 AudioRecord.getMinBufferSize()计算所需的最小缓冲区大小)。参数最终会传递给 Native 层的 AudioRecord对象,并通过AudioSystem与 Android系统的音频服务 (AudioFlinger) 进行交互,申请和配置音频输入资源。初始化成功后native层的AudioRecord会拿到AudioFlinger的 Binder 代理对象,之后就是使用binder进行通信。
1.1 音频源
//位于MediaRecorder类 public final class AudioSource { public static final int CAMCORDER = 5; public static final int DEFAULT = 0; public static final int MIC = 1; public static final int REMOTE_SUBMIX = 8; public static final int UNPROCESSED = 9; public static final int VOICE_CALL = 4; public static final int VOICE_COMMUNICATION = 7; public static final int VOICE_DOWNLINK = 3; public static final int VOICE_PERFORMANCE = 10; public static final int VOICE_RECOGNITION = 6; public static final int VOICE_UPLINK = 2; AudioSource() { throw new RuntimeException("Stub!"); } }音频源 | 主要特点 | 典型应用场景 | 延迟 | 音质 |
|---|---|---|---|---|
DEFAULT (0) | 系统默认音频源,行为可能因设备而异 | 通用录音,不明确要求时使用 | 一般 | 一般 |
MIC (1) | 主麦克风,未经特殊处理 | 普通录音、语音备忘录 | 低 | 较好 |
VOICE_CALL (4) | 通话上下行音频(双向) | 录制整个通话过程(双方声音) | 最低 | 电话音质(窄频) |
VOICE_UPLINK (2) | 只录制发送给对方的声音 | 只录自己说话,不录对方 | 低 | 电话音质 |
VOICE_DOWNLINK (3) | 只录制从对方接收的声音 | 只录对方声音,不录自己 | 低 | 电话音质 |
VOICE_COMMUNICATION (7) | VoIP 通话优化,有回声消除和降噪 | 微信/QQ 语音通话、视频会议 | 较低 | 语音优化 |
VOICE_RECOGNITION (6) | 语音识别优化,清晰化人声 | 语音助手、语音转文字 | 低 | 语音清晰 |
CAMCORDER (5) | 视频录制专用,通常指向后置麦克风 | 相机 App 录像,指向性更好 | 一般 | 立体声/环境声 |
UNPROCESSED (9) | 原始、未加工的麦克风信号 | 专业音频处理、声学分析 | 低 | 最高(但含噪音) |
REMOTE_SUBMIX (8) | 录制系统播放的音频,不录麦克风 | 屏幕录制、内部音频捕获 | 低 | 同系统输出 |
VOICE_PERFORMANCE (10) | 高性能低延迟语音处理 | 专业音乐/实时处理应用 | 最低 | 高质量语音 |
1.2 采样率
代表1s内的采样次数,采样率越高,越接近真实音频,但是占用空间越大,一般的高质量音乐会使用44.1KHz或者48KHz,如果只是单纯录音听个响,不要求音质,可用使用8KHz或者16KHz
1.3 声道数
即有多少个喇叭播放声音,有单声道、双声道等
//对应的宏定义在AudioFormat类中 public static final int CHANNEL_INVALID = 0; //无效的通道配置。 public static final int CHANNEL_IN_BACK = 32; //后置麦克风输入通道。 public static final int CHANNEL_IN_BACK_PROCESSED = 512; //处理后的后置麦克风输入。 public static final int CHANNEL_IN_DEFAULT = 1; //默认的音频输入通道(通常是主麦克风)。 public static final int CHANNEL_IN_FRONT = 16; //前置麦克风输入通道。 public static final int CHANNEL_IN_FRONT_PROCESSED = 256;//处理后的前置麦克风输入。 public static final int CHANNEL_IN_LEFT = 4; //左声道输入。 public static final int CHANNEL_IN_LEFT_PROCESSED = 64; //处理后的左声道输入。 public static final int CHANNEL_IN_MONO = 16; //单声道输入(通常与 CHANNEL_IN_FRONT相同值,但含义不同)。 public static final int CHANNEL_IN_PRESSURE = 1024; //压力传感器输入(非音频,可能是用于某些特殊传感器数据)。 public static final int CHANNEL_IN_RIGHT = 8; //右声道输入。 public static final int CHANNEL_IN_RIGHT_PROCESSED = 128;//处理后的右声道输入。 public static final int CHANNEL_IN_STEREO = 12; //立体声输入(左 + 右即 4 + 8)。 public static final int CHANNEL_IN_VOICE_DNLINK = 32768; //下行语音通道(例如通话时的听筒输入)。 public static final int CHANNEL_IN_VOICE_UPLINK = 16384; //上行语音通道(例如通话时的麦克风输入)。 public static final int CHANNEL_IN_X_AXIS = 2048; //X轴运动传感器输入(例如加速度计)。 public static final int CHANNEL_IN_Y_AXIS = 4096; //Y轴运动传感器输入。 public static final int CHANNEL_IN_Z_AXIS = 8192; //Z轴运动传感器输入。1.4 采样位深
一次采样数据使用多少个bit存放
//宏定义位于AudioFormat中 public static final int ENCODING_PCM_16BIT = 2; //16bit public static final int ENCODING_PCM_24BIT_PACKED = 21; //24bit public static final int ENCODING_PCM_32BIT = 22; //32bit public static final int ENCODING_PCM_8BIT = 3; //8bit public static final int ENCODING_PCM_FLOAT = 4; //32位浮点数1.5 示例代码
public class MicroPhoneRecorder { private static String TAG = "MicroPhoneRecoder"; private int mFrequency = 8000; private int mChannel = AudioFormat.CHANNEL_IN_MONO; private int mSampleBit = AudioFormat.ENCODING_PCM_16BIT; private String mSavePath; private AudioRecord mAudioRecorder; private byte[] mBuffers = null; private boolean isInit = false; private boolean mIsRecording = false; public MicroPhoneRecorder(int freq, int channel, int sampleBit, String savePath) { Log.d(TAG, "MicroPhoneRecorder() called with: freq = [" + freq + "]" + ", channel= [" + channel + "]" + ", sampleBit= [" + sampleBit + "]" + ", savePath= [" + savePath + "]"); mFrequency = freq; mChannel = channel; mSampleBit = sampleBit; mSavePath = savePath; init(); } @SuppressLint("MissingPermission") private void init() { //使用前需要获取音频录制权限 permission.RECORD_AUDIO if (!isInit) { int size = AudioRecord.getMinBufferSize(mFrequency, mChannel, mSampleBit); mBuffers = new byte[size * 4]; //如果没权限,audioRecord创建会有问题,后面startRecording会抛异常 mAudioRecorder = new AudioRecord(MediaRecorder.AudioSource.MIC, mFrequency, mChannel, mSampleBit, size); isInit = true; } } public void setSavePath(String path) { mSavePath = path; } public void release() { Log.d(TAG, "recorder release"); mAudioRecorder.release(); mAudioRecorder = null; } public boolean StartRecord() { Log.d(TAG, "StartRecord"); boolean result = false; if (mAudioRecorder != null) { try { mIsRecording = true; //读取从AudioRecord读取pcm数据写入文件 new Thread(new Runnable() { @Override public void run() { int nDataRead = 0; DataOutputStream mDataOutputStream = null; //注:如果使用的文件存储目录不是app私有目录,需要申请存储权限 try { mDataOutputStream = new DataOutputStream(new BufferedOutputStream(new FileOutputStream( mSavePath, true))); } catch (Exception e) { Log.d(TAG, "mDataOutputStream create fail Exception= " + e); } while (mIsRecording) { if (mAudioRecorder.getState() == AudioRecord.STATE_INITIALIZED) { Arrays.fill(mBuffers, (byte) 0); try { nDataRead = mAudioRecorder.read(mBuffers, 0, mBuffers.length); } catch (Exception e) { nDataRead = 0; } if (nDataRead > 0) { try { // 将采集到的PCM数据写入文件 if (mDataOutputStream != null) { mDataOutputStream.write(mBuffers, 0, nDataRead); } } catch (Exception e) { Log.e(TAG, "pcm data write fail Exception= " + e); } } } else { //AudioRecord未初始化完,等待50ms try { Thread.sleep(50); } catch (InterruptedException e) { } } } if (mDataOutputStream != null) { try { mDataOutputStream.close(); mDataOutputStream = null; } catch (IOException e) { Log.e(TAG, "mDataOutputStream close fail IOException= " + e); } } } }, "recorder work thread").start(); mAudioRecorder.startRecording(); result = true; Log.d(TAG, "recording..."); } catch (Exception e) { mIsRecording = false; Log.i(TAG, "StartRecord: Exception " + e.toString()); } } else { Log.i(TAG, "StartRecord: mAudioRecorder == null"); } return result; } public void StopRecord() { Log.d(TAG, "StopRecord"); if (mAudioRecorder != null) { mAudioRecorder.stop(); } mIsRecording = false; } public boolean isInitialized() { if (mAudioRecorder == null) { Log.i(TAG, "isInitialized: mAudioRecorder == null"); } else { Log.i(TAG, "isInitialized: state " + mAudioRecorder.getState()); } return mAudioRecorder != null && mAudioRecorder.getState() != AudioRecord.STATE_UNINITIALIZED; } }使用示例
MicroPhoneRecorder microPhoneRecorder; public void startRecord() { //app私有目录 不需要存储权限 File file = new File(getContext().getFilesDir(), "temp.pcm"); if (file.exists()) { file.delete(); } //记得获取录音权限 microPhoneRecorder = new MicroPhoneRecorder( 8000, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT, file.getPath() ); boolean result = microPhoneRecorder.StartRecord(); Log.d(TAG, "result = " + result); } public void stopRecord() { microPhoneRecorder.StopRecord(); } public void releaseRecorder() { microPhoneRecorder.release(); }2.音频试听(pcm播放)
安卓中可以使用AudioTrack进行pcm的播放,但是此类不支持解码,所以不能播放mp3等编码后的音频。
AudioTrack,它是Audio系统对外提供的API,MediaPlayer在播放音乐时最终用到的也是它,它是最基本的音频数据输出类。在java层构造函数需要传音频流类型,采样率,声道数,缓冲区大小,数据加载模式。
2.1 音频流类型,一般用music即可
//宏定义位于AudioManager public static final int STREAM_ACCESSIBILITY = 10; public static final int STREAM_ALARM = 4; public static final int STREAM_DTMF = 8; public static final int STREAM_MUSIC = 3; public static final int STREAM_NOTIFICATION = 5; public static final int STREAM_RING = 2; public static final int STREAM_SYSTEM = 1; public static final int STREAM_VOICE_CALL = 0;流类型 | 常量值 | 用途说明 | 音量控制 | 特点 |
|---|---|---|---|---|
STREAM_VOICE_CALL | 0 | 语音通话 | 通话音量 | 最高优先级,通话时其他音频会被暂停/降低 |
STREAM_SYSTEM | 1 | 系统声音 | 系统音量 | 按键音、锁屏音、UI反馈音 |
STREAM_RING | 2 | 来电铃声 | 铃声音量 | 来电、消息铃声 |
STREAM_MUSIC | 3 | 媒体播放 | 媒体音量 | 最常用,音乐、视频、游戏音效 |
STREAM_ALARM | 4 | 闹钟 | 闹钟音量 | 优先级高,即使静音也会响 |
STREAM_NOTIFICATION | 5 | 通知音 | 通知音量 | 短信、推送通知声音 |
STREAM_DTMF | 8 | 拨号音 | DTMF音量 | 电话拨号键盘音(0-9, *, #) |
STREAM_ACCESSIBILITY | 10 | 无障碍 | 媒体音量 | 屏幕阅读器等(API 26+) |
2.2 加载模式,其中加载模式有流式和静态。
流式通过write一次次把音频数据写到AudioTrack中,也就是先写进去多少,AudioTrack就播放多少,后面再继续写继续播放;这种工作方式由于每次都需要把数据从用户提供的Buffer中拷贝到AudioTrack内部的Buffer中,这在一定程度上会引起延时;
静态在播放之前就把所有的数据通过一次write调用传递到AudioTrack的内部缓冲区中,后续就不必再传递数据了。
基于此区别,流式适合长音频、实时音频、占用内存空间小,但是延迟较高;静态适合短音频,延迟较低,占用空间较多。
//宏定义位于AudioTrack类中 public static final int MODE_STATIC = 0; //静态 public static final int MODE_STREAM = 1; //流式2.3 示例代码
public class PcmPlayer { private static String TAG = "PcmPlayer"; private int mChannel = AudioFormat.CHANNEL_OUT_MONO; private int mSampleBit = AudioFormat.ENCODING_PCM_16BIT; private int mFrequency = 8000; private String mFilePath; private AudioTrack audioTrack; private int mPausePosition = 0; //暂停的位置 private FileInputStream fileInputStream = null; //播放文件的输入流 public PcmPlayer( String filePath, int frequency, int channel, int sampleBit) { Log.d(TAG, "PcmPlayer call with filePath=[" + filePath + "]" + ", frequency=[" + frequency + "]" + ", channel=[" + channel + "]" + ", sampleBit=[" + sampleBit + "]"); mFilePath = filePath; mFrequency = frequency; mChannel = channel; mSampleBit = sampleBit; init(); } private void init() { int minBufSize = AudioTrack.getMinBufferSize(mFrequency, mChannel, mSampleBit); audioTrack = new AudioTrack( AudioManager.STREAM_MUSIC, mFrequency, mChannel, mSampleBit, minBufSize * 4, AudioTrack.MODE_STREAM ); //如果使用static加载模式,buffer至少要能存储整个pcm文件 } //修改要播放的文件路径 public void setFilePath(String filePath) { mFilePath = filePath; } //播放pcm public void playPcm(){ Thread playThrad = new Thread(new Runnable() { @Override public void run() { Log.d(TAG, "playPcm"); if (audioTrack == null) { Log.d(TAG, "audioTrack == null"); return; } try { //如果不是app私有目录,需要先获取存储权限 File recordFile = new File(mFilePath); if (!recordFile.exists()) { Log.e(TAG, "file not exist"); audioTrack.stop(); return; } //如果是暂停状态,不重新创建文件流,因为需要恢复播放 if (audioTrack.getPlayState() != AudioTrack.PLAYSTATE_PAUSED) { fileInputStream = new FileInputStream(recordFile); } byte[] buffer = new byte[1024]; // 使用合适的缓冲区大小 int bytesRead; audioTrack.play(); // 读取并播放PCM数据 while (audioTrack.getPlayState() == AudioTrack.PLAYSTATE_PLAYING && (bytesRead = fileInputStream.read(buffer)) >= 0) { audioTrack.write(buffer, 0, bytesRead); // 直接播放读取的数据 } Log.d(TAG, "audioTrack.getPlayState()= " + audioTrack.getPlayState()); if (audioTrack.getPlayState() == AudioTrack.PLAYSTATE_PLAYING) { LogUtil.d(TAG, "正常播放完,没有被外部取消"); fileInputStream.close(); fileInputStream = null; //listener.onfinished(); //如果需要在播放后执行一些逻辑,可以setListener进来 } else if (audioTrack.getPlayState() == AudioTrack.PLAYSTATE_STOPPED) { LogUtil.d(TAG, "外部停止播放"); fileInputStream.close(); fileInputStream = null; //listener.onStop(); } else if (audioTrack.getPlayState() == AudioTrack.PLAYSTATE_PAUSED) { LogUtil.d(TAG, "外部暂停播放"); //listener.onPause(); } } catch (IOException e) { Log.e(TAG, "FileInputStream fail IOException= " + e); } } }, "pcmPlayer thread"); playThrad.start(); } //停止pcm播放,下次调用playPcm时从头开始播 public void stopPcm() { Log.d(TAG, "stopPcm"); if (audioTrack != null) { audioTrack.stop(); mPausePosition = 0; try { if (fileInputStream != null) { fileInputStream.close(); fileInputStream = null; } } catch (IOException e) { Log.e(TAG, "fileInputStream.close fail IOException= " + e); } } } //暂停播放pcm, 下次调用playPcm时从暂停地方继续 public void pausePcm() { Log.d(TAG, "pausePcm"); if (audioTrack != null) { audioTrack.pause(); mPausePosition = audioTrack.getPlaybackHeadPosition(); Log.d(TAG, "mPausePosition = " + mPausePosition); } } //释放资源 public void releasePlayer() { Log.d(TAG, "releasePlayer"); if (audioTrack != null) { audioTrack.stop(); audioTrack.release(); audioTrack = null; try { if (fileInputStream != null) { fileInputStream.close(); fileInputStream = null; } } catch (IOException e) { Log.e(TAG, "fileInputStream.close fail IOException= " + e); } } } //设置播放结束的listener // public void setListener(Listener listener) { // // } }使用示例
PcmPlayer pcmPlayer; //播放pcm public void startPlayPcm() { //app私有目录 不需要存储权限 File file = new File(getContext().getFilesDir(), "temp.pcm"); pcmPlayer = new PcmPlayer(file.getPath(), 8000, AudioFormat.CHANNEL_OUT_MONO, AudioFormat.ENCODING_PCM_16BIT); pcmPlayer.playPcm(); } //暂停 public void pausePcm() { pcmPlayer.pausePcm(); } //停止播放 public void stopPcm() { pcmPlayer.stopPcm(); } //恢复播放, 如果之前是停止播放,那么这里从头开始播放 public void resumePcm() { pcmPlayer.playPcm(); } //释放资源 public void releasePlayer() { pcmPlayer.releasePlayer(); }3. 音频试听(mp3等编码格式播放)
播放已经编码的音频文件,需要播放器支持解码,一般使用MediaPlayer即可,MediaPlayer支持播放视频和音频,可以自动识别文件类型解码,支持网络流播放。
使用MediaPlayer需要注意状态的变化,特别是涉及暂停,恢复,重新播放,切换文件等,因为MediaPlayer使用状态机实现,状态不对的话会抛异常
3.1 示例代码
public class AudioPlayer { private static String TAG = "AudioPlayer"; private MediaPlayer mPlayer; private boolean isPaused = false; //是否处于暂停状态 private PlayStateListener listener; //外部传入的监听器,用于将播放状态通知外部调用 public interface PlayStateListener { void onPrepared(); void onCompletion(); void onError(int what, int extra); } public AudioPlayer() { mPlayer = new MediaPlayer(); mPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC); // 设置音频流类型 } //设置MediaPlayer播放状态的监听器 private void initPlayerListener() { Log.d(TAG, "initPlayerListener"); if (mPlayer == null) { Log.e(TAG, "mPlayer == null"); return; } // 准备完成监听器 mPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() { @Override public void onPrepared(MediaPlayer mp) { LogUtil.d(TAG, "准备完成,开始播放"); mp.start(); // 准备完成后开始播放 if (listener != null) { listener.onPrepared(); //回调通知外部,已经准备完成开始播放 } } }); // 播放完成监听器 mPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() { @Override public void onCompletion(MediaPlayer mp) { LogUtil.d(TAG, "播放完成"); if (listener != null) { listener.onCompletion(); //通知外部播放完成 } } }); // 播放错误监听器 mPlayer.setOnErrorListener(new MediaPlayer.OnErrorListener() { @Override public boolean onError(MediaPlayer mp, int what, int extra) { LogUtil.e(TAG, "播放发生错误"); LogUtil.e(TAG, "MediaPlayer error: what=" + what + ", extra=" + extra); if (listener != null) { listener.onError(what, extra); //通知外部播放器错误 } releasePlayer(); return true; // 返回true表示错误已被处理 } }); LogUtil.d(TAG, "监听器设置完成"); } //设置音频文件路径 public void setFilePath(String filePath) { Log.d(TAG, "setFilePath filePath= " + filePath); if (mPlayer == null) { Log.e(TAG, "mPlayer == null"); return; } //正在播放,先停止并重置 if (mPlayer.isPlaying()) { stopPlay(); mPlayer.reset(); } //如果播放的音频不在app私有目录,需要存储权限 try { mPlayer.setDataSource(filePath); // 设置音频文件路径 initPlayerListener(); //重新设置监听,setDataSource监听器会被清除 isPaused = false; } catch (IOException e) { Log.e(TAG, "setDataSource fail IOException= " + e); releasePlayer(); } } //设置回调,用于获取播放状态 public void setPlayStateListener(PlayStateListener listener) { this.listener = listener; } //开始播放 public void startPlay() { LogUtil.d(TAG, "startPlay"); if (mPlayer == null) { Log.e(TAG, "mPlayer == null"); return; } // 异步准备,防止阻塞UI线程 mPlayer.prepareAsync(); } //停止播放 public void stopPlay() { LogUtil.d(TAG, "stopPlay"); if (mPlayer == null) { Log.e(TAG, "mPlayer == null"); return; } mPlayer.stop(); isPaused = false; } //暂停播放 public void pausePlay() { LogUtil.d(TAG, "pausePlay"); if (mPlayer == null) { Log.e(TAG, "mPlayer == null"); return; } mPlayer.pause(); isPaused = true; Log.d(TAG, "当前播放的时间(ms) mPlayer.getCurrentPosition()= " + mPlayer.getCurrentPosition()); } //恢复播放 public void resumePlay() { LogUtil.d(TAG, "resumePlay"); if (mPlayer == null) { Log.e(TAG, "mPlayer == null"); return; } if (isPaused) { Log.d(TAG, "继续播放"); mPlayer.start(); isPaused = false; } else { Log.d(TAG, "不在暂停状态,重新开始播放"); startPlay(); } } //释放资源 public void releasePlayer() { LogUtil.d(TAG, "releasePlayer"); if (mPlayer != null) { mPlayer.stop(); mPlayer.release(); mPlayer = null; } } }使用示例
AudioPlayer audioPlayer = new AudioPlayer(); public void startPlayAudio() { //app私有目录 不需要存储权限 File file = new File(getContext().getFilesDir(), "sample.mp3"); //设置播放路径 audioPlayer.setFilePath(file.getPath()); //设置播放状态监听 audioPlayer.setPlayStateListener(new AudioPlayer.PlayStateListener() { @Override public void onPrepared() { //播放器准备完成,开始播放了 Log.d(TAG, "onPrepared 播放器准备完成,开始播放了"); } @Override public void onCompletion() { //已经播放完成 Log.d(TAG, "onCompletion 播放完成"); } @Override public void onError(int what, int extra) { //播放过程发生错误 Log.e(TAG, "onError 播放错误 what= " + what + ", extra= " + extra); } }); //播放 audioPlayer.startPlay(); } public void stopPlayAudio() { audioPlayer.stopPlay(); } public void pasuePlayAudio() { audioPlayer.pausePlay(); } public void resumePlayAudio() { auidoPlayer.resumePlay(); } public void releasePlayer() { audioPlayer.releasePlayer(); }