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之前項(xiàng)目需要實(shí)現(xiàn)MP3的錄音,于是使用上了Lame這個庫。這次做一個demo,使用AndroidStudio+Cmake+NDK進(jìn)行開發(fā)。利用Android SDK提供的AndroidRecorder進(jìn)行錄音,得到PCM數(shù)據(jù),并使用jni調(diào)用Lame這個C庫將PCM數(shù)據(jù)轉(zhuǎn)換為MP3文件。并使用MediaPlayer對錄音的MP3文件進(jìn)行播放。另外此次的按鍵是仿微信的語音按鍵,按下錄音,松開結(jié)束,若中途上滑松開即取消
效果如下:
項(xiàng)目地址: LameMp3ForAndroid_jb51.rar
一、主要類的介紹
二、錄制的流程
三、主要的實(shí)現(xiàn)代碼
Mp3Recorder
public class Mp3Recorder { static { System.loadLibrary("lamemp3"); } //默認(rèn)采樣率 private static final int DEFAULT_SAMPLING_RATE = 44100; //轉(zhuǎn)換周期,錄音每滿160幀,進(jìn)行一次轉(zhuǎn)換 private static final int FRAME_COUNT = 160; //輸出MP3的碼率 private static final int BIT_RATE = 32; //根據(jù)資料假定的最大值。 實(shí)測時有時超過此值。 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; //循環(huán)的從AudioRecord獲取錄音的PCM數(shù)據(jù) while (isRecording) { int readSize = audioRecord.read(mPCMBuffer, 0, bufferSize); if (readSize > 0) { //待轉(zhuǎn)換的PCM數(shù)據(jù)放到轉(zhuǎn)換線程中 encodeThread.addChangeBuffer(mPCMBuffer,readSize); calculateRealVolume(mPCMBuffer, readSize); } } // 錄音完畢,釋放AudioRecord的資源 try { audioRecord.stop(); audioRecord.release(); audioRecord = null; // 錄音完畢,通知轉(zhuǎn)換線程停止,并等待直到其轉(zhuǎn)換完畢 Message msg = Message.obtain(encodeThread.getHandler(), DataEncodeThread.PROCESS_STOP); msg.sendToTarget(); encodeThread.join(); //轉(zhuǎn)換完畢后回調(diào)監(jiān)聽 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; } //計(jì)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(); //計(jì)算緩沖區(qū)的大小,使其是設(shè)置周期幀數(shù)的整數(shù)倍,方便循環(huán) 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); // 創(chuàng)建轉(zhuǎn)碼的線程 encodeThread = new DataEncodeThread(os, bufferSize); encodeThread.start(); //給AudioRecord設(shè)置刷新監(jiān)聽,待錄音幀數(shù)每次達(dá)到FRAME_COUNT,就通知轉(zhuǎn)換線程轉(zhuǎn)換一次數(shù)據(jù) audioRecord.setRecordPositionUpdateListener(encodeThread, encodeThread.getHandler()); audioRecord.setPositionNotificationPeriod(FRAME_COUNT); } }
DataEncodeThread
public class DataEncodeThread extends Thread implements AudioRecord.OnRecordPositionUpdateListener { public static final int PROCESS_STOP = 1; private StopHandler handler; private byte[] mp3Buffer; //用于存取待轉(zhuǎn)換的PCM數(shù)據(jù) 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(); //錄音停止后,將剩余的PCM數(shù)據(jù)轉(zhuǎn)換完畢 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進(jìn)行回調(diào),滿足幀數(shù),通知數(shù)據(jù)轉(zhuǎn)換 processData(); } //從緩存區(qū)ChangeBuffers里獲取待轉(zhuǎn)換的PCM數(shù)據(jù),轉(zhuǎn)換為MP3數(shù)據(jù),并寫入文件 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; } } }
SimpleLame 主要的邏輯是通過jni調(diào)用Lame庫
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); }
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