利用libmp3lame实现在Android上录音MP3文件示例

public class Mp3Recorder {  static {    System.loadLibrary("lamemp3");  }  //默认采样率  private static final int DEFAULT_SAMPLING_RATE = 44100;  //转换周期，录音每满160帧，进行一次转换  private static final int FRAME_COUNT = 160;  //输出MP3的码率  private static final int BIT_RATE = 32;  //根据资料假定的最大值。 实测时有时超过此值。  private static final int MAX_VOLUME = 2000;  private AudioRecord audioRecord = null;  private int bufferSize;  private File mp3File;  private int mVolume;  private short[] mPCMBuffer;  private FileOutputStream os = null;  private DataEncodeThread encodeThread;  private int samplingRate;  private int channelConfig;  private PCMFormat audioFormat;  private boolean isRecording = false;  private ExecutorService executor = Executors.newFixedThreadPool(1);  private OnFinishListener finishListener;  public interface OnFinishListener {    void onFinish(String mp3SavePath);  }  public Mp3Recorder(int samplingRate, int channelConfig, PCMFormat audioFormat) {    this.samplingRate = samplingRate;    this.channelConfig = channelConfig;    this.audioFormat = audioFormat;  }  public Mp3Recorder() {    this(DEFAULT_SAMPLING_RATE, AudioFormat.CHANNEL_IN_MONO, PCMFormat.PCM_16BIT);  }  public void startRecording(File mp3Save) throws IOException {    if (isRecording) return;    this.mp3File = mp3Save;    if (audioRecord == null) {      initAudioRecorder();    }    audioRecord.startRecording();    Runnable runnable = new Runnable() {      @Override      public void run() {        isRecording = true;        //循环的从AudioRecord获取录音的PCM数据        while (isRecording) {          int readSize = audioRecord.read(mPCMBuffer, 0, bufferSize);          if (readSize > 0) {            //待转换的PCM数据放到转换线程中            encodeThread.addChangeBuffer(mPCMBuffer,readSize);            calculateRealVolume(mPCMBuffer, readSize);          }        }        // 录音完毕，释放AudioRecord的资源        try {          audioRecord.stop();          audioRecord.release();          audioRecord = null;          // 录音完毕，通知转换线程停止，并等待直到其转换完毕          Message msg = Message.obtain(encodeThread.getHandler(), DataEncodeThread.PROCESS_STOP);          msg.sendToTarget();          encodeThread.join();          //转换完毕后回调监听          if(finishListener != null) finishListener.onFinish(mp3File.getPath());        } catch (InterruptedException e) {          e.printStackTrace();        } finally {          if (os != null) {            try {              os.close();            } catch (IOException e) {              e.printStackTrace();            }          }        }      }    };    executor.execute(runnable);  }  public void stopRecording() throws IOException {    isRecording = false;  }  //计算音量大小  private void calculateRealVolume(short[] buffer, int readSize) {    double sum = 0;    for (int i = 0; i < readSize; i++) {      sum += buffer[i] * buffer[i];    }    if (readSize > 0) {      double amplitude = sum / readSize;      mVolume = (int) Math.sqrt(amplitude);    }  }  public int getVolume(){    if (mVolume >= MAX_VOLUME) {      return MAX_VOLUME;    }    return mVolume;  }  public int getMaxVolume(){    return MAX_VOLUME;  }  public void setFinishListener(OnFinishListener listener){    this.finishListener = listener;  }  private void initAudioRecorder() throws IOException {    int bytesPerFrame = audioFormat.getBytesPerFrame();    //计算缓冲区的大小，使其是设置周期帧数的整数倍，方便循环    int frameSize = AudioRecord.getMinBufferSize(samplingRate, channelConfig, audioFormat.getAudioFormat()) / bytesPerFrame;    if (frameSize % FRAME_COUNT != 0) {      frameSize = frameSize + (FRAME_COUNT - frameSize % FRAME_COUNT);    }    bufferSize = frameSize * bytesPerFrame;    audioRecord = new AudioRecord(MediaRecorder.AudioSource.MIC, samplingRate, channelConfig, audioFormat.getAudioFormat(), bufferSize);    mPCMBuffer = new short[bufferSize];    SimpleLame.init(samplingRate, 1, samplingRate, BIT_RATE);    os = new FileOutputStream(mp3File);    // 创建转码的线程    encodeThread = new DataEncodeThread(os, bufferSize);    encodeThread.start();    //给AudioRecord设置刷新监听，待录音帧数每次达到FRAME_COUNT，就通知转换线程转换一次数据    audioRecord.setRecordPositionUpdateListener(encodeThread, encodeThread.getHandler());    audioRecord.setPositionNotificationPeriod(FRAME_COUNT);  }}

public class DataEncodeThread extends Thread implements AudioRecord.OnRecordPositionUpdateListener {  public static final int PROCESS_STOP = 1;  private StopHandler handler;  private byte[] mp3Buffer;  //用于存取待转换的PCM数据  private List<ChangeBuffer> mChangeBuffers = Collections.synchronizedList(new LinkedList<ChangeBuffer>());  private FileOutputStream os;  private CountDownLatch handlerInitLatch = new CountDownLatch(1);  private static class StopHandler extends Handler {    WeakReference<DataEncodeThread> encodeThread;    public StopHandler(DataEncodeThread encodeThread) {      this.encodeThread = new WeakReference<>(encodeThread);    }    @Override    public void handleMessage(Message msg) {      if (msg.what == PROCESS_STOP) {        DataEncodeThread threadRef = encodeThread.get();        //录音停止后，将剩余的PCM数据转换完毕        for (;threadRef.processData() > 0;);        removeCallbacksAndMessages(null);        threadRef.flushAndRelease();        getLooper().quit();      }      super.handleMessage(msg);    }  }  public DataEncodeThread(FileOutputStream os, int bufferSize) {    this.os = os;    mp3Buffer = new byte[(int) (7200 + (bufferSize * 2 * 1.25))];  }  @Override  public void run() {    Looper.prepare();    handler = new StopHandler(this);    handlerInitLatch.countDown();    Looper.loop();  }  public Handler getHandler() {    try {      handlerInitLatch.await();    } catch (InterruptedException e) {      e.printStackTrace();      Log.e(TAG, "Error when waiting handle to init");    }    return handler;  }  @Override  public void onMarkerReached(AudioRecord recorder) {    // Do nothing  }  @Override  public void onPeriodicNotification(AudioRecord recorder) {    //由AudioRecord进行回调，满足帧数，通知数据转换    processData();  }  //从缓存区ChangeBuffers里获取待转换的PCM数据，转换为MP3数据,并写入文件  private int processData() {    if(mChangeBuffers != null && mChangeBuffers.size() > 0) {      ChangeBuffer changeBuffer = mChangeBuffers.remove(0);      short[] buffer = changeBuffer.getData();      int readSize = changeBuffer.getReadSize();      Log.d(TAG, "Read size: " + readSize);      if (readSize > 0) {        int encodedSize = SimpleLame.encode(buffer, buffer, readSize, mp3Buffer);        if (encodedSize < 0) {          Log.e(TAG, "Lame encoded size: " + encodedSize);        }        try {          os.write(mp3Buffer, 0, encodedSize);        } catch (IOException e) {          e.printStackTrace();          Log.e(TAG, "Unable to write to file");        }        return readSize;      }    }    return 0;  }  private void flushAndRelease() {    final int flushResult = SimpleLame.flush(mp3Buffer);    if (flushResult > 0) {      try {        os.write(mp3Buffer, 0, flushResult);      } catch (final IOException e) {        e.printStackTrace();      }    }  }  public void addChangeBuffer(short[] rawData, int readSize){    mChangeBuffers.add(new ChangeBuffer(rawData, readSize));  }  private class ChangeBuffer{    private short[] rawData;    private int readSize;    public ChangeBuffer(short[] rawData, int readSize){      this.rawData = rawData.clone();      this.readSize = readSize;    }    public short[] getData(){      return rawData;    }    public int getReadSize(){      return readSize;    }  }}

public class SimpleLame {  public native static void close();  public native static int encode(short[] buffer_l, short[] buffer_r, int samples, byte[] mp3buf);  public native static int flush(byte[] mp3buf);  public native static void init(int inSampleRate, int outChannel, int outSampleRate, int outBitrate, int quality);  public static void init(int inSampleRate, int outChannel, int outSampleRate, int outBitrate) {    init(inSampleRate, outChannel, outSampleRate, outBitrate, 7);  }}

#include <cwchar>#include "SimpleLame.h"#include "lamemp3/lame.h"static lame_global_flags *glf = NULL;void Java_com_clam314_lame_SimpleLame_close(JNIEnv *env, jclass type){  lame_close(glf);  glf = NULL;}jint Java_com_clam314_lame_SimpleLame_encode(JNIEnv *env, jclass type, jshortArray buffer_l_,                    jshortArray buffer_r_, jint samples, jbyteArray mp3buf_) {  jshort *buffer_l = env->GetShortArrayElements(buffer_l_, NULL);  jshort *buffer_r = env->GetShortArrayElements(buffer_r_, NULL);  jbyte *mp3buf = env->GetByteArrayElements(mp3buf_, NULL);  const jsize mp3buf_size = env->GetArrayLength(mp3buf_);  int result =lame_encode_buffer(glf, buffer_l, buffer_r, samples, (u_char*)mp3buf, mp3buf_size);  env->ReleaseShortArrayElements(buffer_l_, buffer_l, 0);  env->ReleaseShortArrayElements(buffer_r_, buffer_r, 0);  env->ReleaseByteArrayElements(mp3buf_, mp3buf, 0);  return result;}jint Java_com_clam314_lame_SimpleLame_flush(JNIEnv *env, jclass type, jbyteArray mp3buf_) {  jbyte *mp3buf = env->GetByteArrayElements(mp3buf_, NULL);  const jsize mp3buf_size = env->GetArrayLength(mp3buf_);  int result = lame_encode_flush(glf, (u_char*)mp3buf, mp3buf_size);  env->ReleaseByteArrayElements(mp3buf_, mp3buf, 0);  return result;}void Java_com_clam314_lame_SimpleLame_init__IIIII(JNIEnv *env, jclass type, jint inSampleRate, jint outChannel,                       jint outSampleRate, jint outBitrate, jint quality) {  if(glf != NULL){    lame_close(glf);    glf = NULL;  }  glf = lame_init();  lame_set_in_samplerate(glf, inSampleRate);  lame_set_num_channels(glf, outChannel);  lame_set_out_samplerate(glf, outSampleRate);  lame_set_brate(glf, outBitrate);  lame_set_quality(glf, quality);  lame_init_params(glf);}