Android为我们提供了两个音频处理的API：AudioRecord和MediaRecorder
AudioRecord：偏底层的api
MediaRecorder：对AudioRecord进行包装的api
一、使用AudioRecord录制pcm编码的音频
首先需要录音权限，API>=6.0还需要动态申请 （动态申请权限代码略过，详情见文末源码）<uses-permission android:name="android.permission.RECORD_AUDIO" />
二、录制主要分为一下几步
创建AudioRecord设置参数 录音来源采样率录制的声道数据格式录制的缓冲区大小 开启一个线程读取音频数据创建一个AduioRecord工具类
public class AudioRecordUtil {//设置音频采样率，44100是目前的标准，但是某些设备仍然支持22050，16000，11025private final int sampleRateInHz = 44100;//设置音频的录制的声道CHANNEL_IN_STEREO为双声道，CHANNEL_CONFIGURATION_MONO为单声道private final int channelConfig = AudioFormat.CHANNEL_IN_STEREO;//音频数据格式:PCM 16位每个样本。保证设备支持。PCM 8位每个样本。不一定能得到设备支持。private final int audioFormat = AudioFormat.ENCODING_PCM_16BIT;//录制状态private boolean recorderState = true;private byte[] buffer;private AudioRecord audioRecord;private static AudioRecordUtil audioRecordUtil = new AudioRecordUtil();public static AudioRecordUtil getInstance() {return audioRecordUtil;}private AudioRecordUtil() {init();}private void init() {int recordMinBufferSize = AudioRecord.getMinBufferSize(sampleRateInHz, channelConfig, audioFormat);//指定 AudioRecord 缓冲区大小buffer = new byte[recordMinBufferSize];//根据录音参数构造AudioRecord实体对象audioRecord = new AudioRecord(MediaRecorder.AudioSource.MIC, sampleRateInHz, channelConfig,audioFormat, recordMinBufferSize);}/*** 开始录制*/public void start() {if (audioRecord.getState() == AudioRecord.RECORDSTATE_STOPPED) {recorderState = true;audioRecord.startRecording();new RecordThread().start();}}/*** 停止录制*/public void stop() {recorderState = false;if (audioRecord.getState() == AudioRecord.RECORDSTATE_RECORDING) {audioRecord.stop();}audioRecord.release();}private class RecordThread extends Thread {@Overridepublic void run() {while (recorderState) {int read = audioRecord.read(buffer, 0, buffer.length);if (AudioRecord.ERROR_INVALID_OPERATION != read) {//获取到的pcm数据就是buffer了Log.d("TAG", String.valueOf(buffer.length));}}}}}
启动录音
AudioRecordUtil.getInstance().start();
停止录音
AudioRecordUtil.getInstance().stop();
在子线程中读取到的buffer数据就是音频数据了，还是比较简单的
三、PCM的音频原数据已经获取到了，现在就对他进行AAC编码
编码器的采样率必须与录制的时候保持一致public class PCMEncoderAAC {//比特率private final static int KEY_BIT_RATE = 96000;//读取数据的最大字节数private final static int KEY_MAX_INPUT_SIZE = 1024 * 1024;//声道数private final static int CHANNEL_COUNT = 2;private MediaCodec mediaCodec;private ByteBuffer[] encodeInputBuffers;private ByteBuffer[] encodeOutputBuffers;private MediaCodec.BufferInfo encodeBufferInfo;private EncoderListener encoderListener;public PCMEncoderAAC(int sampleRate, EncoderListener encoderListener) {this.encoderListener = encoderListener;init(sampleRate);}/*** 初始化AAC编码器*/private void init(int sampleRate) {try {//参数对应-> mime type、采样率、声道数MediaFormat encodeFormat = MediaFormat.createAudioFormat(MediaFormat.MIMETYPE_AUDIO_AAC,sampleRate, CHANNEL_COUNT);//比特率encodeFormat.setInteger(MediaFormat.KEY_BIT_RATE, KEY_BIT_RATE);encodeFormat.setInteger(MediaFormat.KEY_AAC_PROFILE, MediaCodecInfo.CodecProfileLevel.AACObjectLC);encodeFormat.setInteger(MediaFormat.KEY_MAX_INPUT_SIZE, KEY_MAX_INPUT_SIZE);mediaCodec = MediaCodec.createEncoderByType(MediaFormat.MIMETYPE_AUDIO_AAC);mediaCodec.configure(encodeFormat, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);} catch (IOException e) {e.printStackTrace();}mediaCodec.start();encodeInputBuffers = mediaCodec.getInputBuffers();encodeOutputBuffers = mediaCodec.getOutputBuffers();encodeBufferInfo = new MediaCodec.BufferInfo();}/*** @param data*/public void encodeData(byte[] data) {//dequeueInputBuffer（time）需要传入一个时间值，-1表示一直等待，0表示不等待有可能会丢帧，其他表示等待多少毫秒//获取输入缓存的indexint inputIndex = mediaCodec.dequeueInputBuffer(-1);if (inputIndex >= 0) {ByteBuffer inputByteBuf = encodeInputBuffers[inputIndex];inputByteBuf.clear();//添加数据inputByteBuf.put(data);//限制ByteBuffer的访问长度inputByteBuf.limit(data.length);//把输入缓存塞回去给MediaCodecmediaCodec.queueInputBuffer(inputIndex, 0, data.length, 0, 0);}//获取输出缓存的indexint outputIndex = mediaCodec.dequeueOutputBuffer(encodeBufferInfo, 0);while (outputIndex >= 0) {//获取缓存信息的长度int byteBufSize = encodeBufferInfo.size;//添加ADTS头部后的长度int bytePacketSize = byteBufSize + 7;//拿到输出BufferByteBuffer outPutBuf = encodeOutputBuffers[outputIndex];outPutBuf.position(encodeBufferInfo.offset);outPutBuf.limit(encodeBufferInfo.offset + encodeBufferInfo.size);byte[] aacData = new byte[bytePacketSize];//添加ADTS头部addADTStoPacket(aacData, bytePacketSize);/*get（byte[] dst,int offset,int length）:ByteBuffer从position位置开始读，读取length个byte，并写入dst下标从offset到offset + length的区域*/outPutBuf.get(aacData, 7, byteBufSize);outPutBuf.position(encodeBufferInfo.offset);//编码成功if (encoderListener != null) {encoderListener.encodeAAC(aacData);}//释放mediaCodec.releaseOutputBuffer(outputIndex, false);outputIndex = mediaCodec.dequeueOutputBuffer(encodeBufferInfo, 0);}}/*** 添加ADTS头*/private void addADTStoPacket(byte[] packet, int packetLen) {// AAC LCint profile = 2;// 44.1KHzint freqIdx = 4;// CPEint chanCfg = 2;// fill in ADTS datapacket[0] = (byte) 0xFF;packet[1] = (byte) 0xF9;packet[2] = (byte) (((profile - 1) << 6) + (freqIdx << 2) + (chanCfg >> 2));packet[3] = (byte) (((chanCfg & 3) << 6) + (packetLen >> 11));packet[4] = (byte) ((packetLen & 0x7FF) >> 3);packet[5] = (byte) (((packetLen & 7) << 5) + 0x1F);packet[6] = (byte) 0xFC;}public interface EncoderListener {void encodeAAC(byte[] data);}}
使用只需要在上面拿到pcm数据的那里调用encodeData()方法即可
初始化AudioRecordUtil时也同时将编码器初始化好private PCMEncoderAAC pcmEncoderAAC;private void init() {//....//初始化编码器pcmEncoderAAC = new PCMEncoderAAC(sampleRateInHz, this);}@Overridepublic void encodeAAC(byte[] data) {Log.d("TAG", "AAC数据长度：" + data.length);}
开始编码
private class RecordThread extends Thread {@Overridepublic void run() {while (recorderState) {int read = audioRecord.read(buffer, 0, buffer.length);if (AudioRecord.ERROR_INVALID_OPERATION != read) {//获取到的pcm数据就是buffer了Log.d("TAG", String.valueOf(buffer.length));pcmEncoderAAC.encodeData(buffer);}}}}
四、将编码好的音频数据写入文件中
创建的文件输出流private FileOutputStream fileOutputStream;private void init() {//...try {fileOutputStream = new FileOutputStream(new File(App.getAppContext().getExternalCacheDir(), "test.aac"));} catch (FileNotFoundException e) {e.printStackTrace();}}@Overridepublic void encodeAAC(byte[] data) {Log.d("TAG", "AAC数据长度：" + data.length);try {fileOutputStream.write(data);} catch (IOException e) {e.printStackTrace();}}
生成的文件
五、 使用MediaRecorder直接录制AAC编码的音频到文件中
这种录制方式就简单许多了public class MediaRecordUtil {private MediaRecorder mediaRecorder;private static MediaRecordUtil mediaRecordUtil = new MediaRecordUtil();public static MediaRecordUtil getInstance() {return mediaRecordUtil;}private MediaRecordUtil() {init();}private void init() {mediaRecorder = new MediaRecorder();//配置采集方式，这里用的是麦克风的采集方式mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);//配置输出方式，这里用的是AACmediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.AAC_ADTS);//配置采样频率，频率越高月接近原始声音，Android所有设备都支持的采样频率为44100mediaRecorder.setAudioSamplingRate(44100);//配置文件的编码格式,AAC是比较通用的编码格式mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AAC);//配置码率，这里一般通用的是96000mediaRecorder.setAudioEncodingBitRate(96000);//配置录音文件的位置String path = App.getAppContext().getExternalCacheDir() + "/audio.aac";mediaRecorder.setOutputFile(path);}/*** 开始录制*/public void start() {try {mediaRecorder.prepare();mediaRecorder.start();} catch (IOException e) {e.printStackTrace();}}/*** 停止录制*/public void stop() {mediaRecorder.stop();}}
启动录音
MediaRecordUtil.getInstance().start();
停止录音
MediaRecordUtil.getInstance().stop();
生成的文件
六、使用MediaRecorder可以很方便的直接将音频流写入到文件中，那么如果我们需要像AudioRecord那样获取到实时的音频流需要怎么弄呢？
将setOutputFile()的值传递为一个FileDescriptor文件描述符然后开启子线程去读取文件描述符的数据 就是音频流数据了public class MediaRecordUtil {private MediaRecorder mediaRecorder;private static MediaRecordUtil mediaRecordUtil = new MediaRecordUtil();private ParcelFileDescriptor parcelWrite;private DataInputStream inputStream;private boolean recorderState;public static MediaRecordUtil getInstance() {return mediaRecordUtil;}private MediaRecordUtil() {intPipLine();init();}private void intPipLine() {try {ParcelFileDescriptor[] parcelFileDescriptors = ParcelFileDescriptor.createPipe();ParcelFileDescriptor parcelRead = new ParcelFileDescriptor(parcelFileDescriptors[0]);parcelWrite = new ParcelFileDescriptor(parcelFileDescriptors[1]);inputStream = new DataInputStream(new ParcelFileDescriptor.AutoCloseInputStream(parcelRead));} catch (IOException e) {e.printStackTrace();}}private void init() {mediaRecorder = new MediaRecorder();//....//设置获取音频流的方式mediaRecorder.setOutputFile(parcelWrite.getFileDescriptor());}private class RecordThread extends Thread {private byte[] buffer = new byte[900];@Overridepublic void run() {while (recorderState) {try {int read = inputStream.read(buffer);if (read != -1) {byte[] data = Arrays.copyOfRange(buffer, 0, read);Log.e("TAG", "获取到的音频数据：" + data.length);}} catch (IOException e) {e.printStackTrace();}}}}/*** 开始录制*/public void start() {try {recorderState = true;new RecordThread().start();mediaRecorder.prepare();mediaRecorder.start();} catch (IOException e) {e.printStackTrace();}}/*** 停止录制*/public void stop() {recorderState = false;mediaRecorder.stop();}}
