Android使用AudioRecord录制PCM音频、PCM转AAC、使用MediaRecorder直接录制AAC编码音频

aac mediarecorder pcm Android 2022-06-06 13:06:43 549人浏览八月长安

摘要

Android为我们提供了两个音频处理的api：AudioRecord和MediaRecorder AudioRecord：偏底层的api Me

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）

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22050，16000，11025
    private 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);
    }
    
    public void start() {
        if (audioRecord.getState() == AudioRecord.RECORDSTATE_STOPPED) {
            recorderState = true;
            audioRecord.startRecording();
            new RecordThread().start();
        }
    }
    
    public void stop() {
        recorderState = false;
        if (audioRecord.getState() == AudioRecord.RECORDSTATE_RECORDING) {
            audioRecord.stop();
        }
        audioRecord.release();
    }
    private class RecordThread extends Thread {
        @Override
        public 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);
    }
    
    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();
    }
    
    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index
        int 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MediaCodec
            mediaCodec.queueInputBuffer(inputIndex, 0, data.length, 0, 0);
        }
        //获取输出缓存的index
        int 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Buffer
            ByteBuffer 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);
            
            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);
        }
    }
    
    private void addADTStoPacket(byte[] packet, int packetLen) {
        // AAC LC
        int profile = 2;
        // 44.1KHz
        int freqIdx = 4;
        // CPE
        int chanCfg = 2;
        // fill in ADTS data
        packet[0] = (byte) 0xFF;
        packet[1] = (byte) 0xF9;
        packet[2] = (byte) (((profile - 1) << 6) + (freqIdx <> 2));
        packet[3] = (byte) (((chanCfg & 3) <> 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);
}
@Override
public void encodeAAC(byte[] data) {
    Log.d("TAG", "AAC数据长度：" + data.length);
}

开始编码

private class RecordThread extends Thread {
    @Override
    public 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();
    }
}
@Override
public 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

在这里插入图片描述

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AAC
        mediaRecorder.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44100
        mediaRecorder.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96000
        mediaRecorder.setAudioEncodingBitRate(96000);
        //配置录音文件的位置
        String path = App.getAppContext().getExternalCacheDir() + "/audio.aac";
        mediaRecorder.setOutputFile(path);
    }
    
    public void start() {
        try {
            mediaRecorder.prepare();
            mediaRecorder.start();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    
    public void stop() {
        mediaRecorder.stop();
    }
}

启动录音

 MediaRecordUtil.getInstance().start();

停止录音

 MediaRecordUtil.getInstance().stop();

生成的文件

在这里插入图片描述

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];
        @Override
        public 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();
                }
            }
        }
    }
    
    public void start() {
        try {
            recorderState = true;
            new RecordThread().start();
            mediaRecorder.prepare();
            mediaRecorder.start();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    
    public void stop() {
        recorderState = false;
        mediaRecorder.stop();
    }
}

Demo 下载地址
作者：Code-Porter

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本文标题: Android使用AudioRecord录制PCM音频、PCM转AAC、使用MediaRecorder直接录制AAC编码音频

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