Android 采集音頻與音頻解碼

使用AudioRecord采集音頻pcm資料，使用MediaCodec轉化為aac資料

package com.yuanxuzhen.yuanrecord;

import android.content.Context;
import android.media.AudioFormat;
import android.media.AudioRecord;
import android.media.MediaRecorder;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class RecordAudio {
    private int mSampleRate = 44100;
    private int mInChannel = AudioFormat.CHANNEL_IN_STEREO;
    private int mSampleFormat = AudioFormat.ENCODING_PCM_16BIT;

    public int getmChannelCount() {
        return mChannelCount;
    }

    private int mChannelCount = 2;
    private String mFilePath = null;
    private AudioRecord mRecorder = null;
    ExecutorService mExecutorService;
    private int mBufferSize;

    public enum AUDIO_STAUS {
        START,
        PAUSE,
        STOP
    }
    AUDIO_STAUS mStatus;
    public void init(Context context, int sampleRate, int inChannel, int sampleFormat, String filePath) {
        mSampleRate = sampleRate;
        mInChannel = inChannel;
        mSampleFormat = sampleFormat;
        mFilePath = filePath;
        mBufferSize = AudioRecord.getMinBufferSize(mSampleRate,
                mInChannel, mSampleFormat);
        mRecorder = new AudioRecord(MediaRecorder.AudioSource.MIC,
                mSampleRate, mInChannel,
                mSampleFormat,
                mBufferSize);
        mChannelCount = mRecorder.getChannelCount();
        mExecutorService = Executors.newCachedThreadPool();
    }


    public void startRecord() {
        if(mStatus == AUDIO_STAUS.START){
            return;
        }
        if(mStatus == AUDIO_STAUS.STOP){
            File file = new File(mFilePath);
            if(file.exists()){
                file.delete();
            }
        }
        mStatus = AUDIO_STAUS.START;
        mRecorder.startRecording();
        mExecutorService.execute(new Runnable() {
            @Override
            public void run() {
                realStartRecord();
            }
        });
    }

    private void realStartRecord() {
        // Write the output audio in byte
        short sData[] = new short[mBufferSize / 2];
        byte  byteData[] = new byte[mBufferSize];

        FileOutputStream os = null;
        try {
            os = new FileOutputStream(mFilePath, true);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }

        while (mStatus == AUDIO_STAUS.START) {
            // gets the voice output from microphone to byte format
            if(mSampleFormat == AudioFormat.ENCODING_PCM_16BIT){
                int size = mRecorder.read(sData, 0, mBufferSize / 2);
                System.out.println("Short wirting to file size=" + size);
                try {
                    // // writes the data to file from buffer
                    // // stores the voice buffer
                    byte bData[] = short2byte(sData);
                    os.write(bData, 0, mBufferSize);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }else{
                int size = mRecorder.read(byteData, 0, mBufferSize);
                System.out.println("Short wirting to file size=" + size);
                try {
                    // // writes the data to file from buffer
                    // // stores the voice buffer
                    os.write(byteData, 0, mBufferSize);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

        }
        try {
            os.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    //convert short to byte
    private byte[] short2byte(short[] sData) {
        int shortArrsize = sData.length;
        byte[] bytes = new byte[shortArrsize * 2];
        for (int i = 0; i < shortArrsize; i++) {
            bytes[i * 2] = (byte) (sData[i] & 0x00FF);
            bytes[(i * 2) + 1] = (byte) (sData[i] >> 8);
            sData[i] = 0;
        }
        return bytes;

    }


    public void pauseRecord(){
        mStatus = AUDIO_STAUS.PAUSE;
        if(mRecorder != null)
            mRecorder.stop();

    }

    public void stopRecord(){
        mStatus = AUDIO_STAUS.STOP;
        if(mRecorder != null)
            mRecorder.stop();
        release();
    }

    public void release(){
        if(mRecorder == null){
            return;
        }
        mRecorder.release();
        mRecorder = null;
    }


}

下面是aac編碼的操作，難點在于從pcm檔案每次都少資料給編碼器，如果聽到的聲音不對，就調整這個引數， byte[] byteArray = new byte[2048];我這里設定了2048.在ffmpeg中，這個引數來自于編碼器（ffmpeg計算方法是size= nb_sample * channel * bytePerSample）.

package com.yuanxuzhen.yuanrecord;

import android.content.Context;
import android.media.AudioFormat;
import android.media.AudioRecord;
import android.media.MediaCodec;
import android.media.MediaCodecInfo;
import android.media.MediaFormat;
import android.media.MediaRecorder;
import android.os.Build;
import android.util.Log;

import androidx.annotation.RequiresApi;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class EncodeAudioAAC {
    private int mSampleRate = 44100;
    private int mInChannel = AudioFormat.CHANNEL_IN_STEREO;
    private int mSampleFormat = AudioFormat.ENCODING_PCM_16BIT;
    private int mChannelCount = 2;
    private String mDstFilePath = null;
    private String mSrcFilePath = null;
    MediaCodec mEncorder;
    ExecutorService mExecutorService;
    private int mBufferSize;
    private IHandlerCallback mCallback;


    public void init(Context context, int sampleRate,
                     int channelCount, int sampleFormat,
                     String srcPath, String dstPath,
                     IHandlerCallback callback) {
        mSampleRate = sampleRate;
        mChannelCount = channelCount;
        mSampleFormat = sampleFormat;
        mSrcFilePath = srcPath;
        mDstFilePath = dstPath;
        mExecutorService = Executors.newCachedThreadPool();
        mCallback = callback;
        mBufferSize = AudioRecord.getMinBufferSize(mSampleRate,
                mInChannel, mSampleFormat);
        try {
            mEncorder = MediaCodec.createEncoderByType(MediaFormat.MIMETYPE_AUDIO_AAC);
        } catch (Exception e) {
            e.printStackTrace();
        }
        MediaFormat format = MediaFormat.createAudioFormat(MediaFormat.MIMETYPE_AUDIO_AAC,
                mSampleRate,
                mChannelCount);
        format.setString(MediaFormat.KEY_MIME, MediaFormat.MIMETYPE_AUDIO_AAC);
        format.setInteger(MediaFormat.KEY_AAC_PROFILE, MediaCodecInfo.CodecProfileLevel.AACObjectLC);
        format.setInteger(MediaFormat.KEY_BIT_RATE, 100000);
        format.setInteger(MediaFormat.KEY_MAX_INPUT_SIZE, mBufferSize);
        mEncorder.configure(format, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
    }


    /**
     * 開始編碼
     */
    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
    public void startEncording() {
        if (mEncorder == null) {
            if(mCallback != null){
                mCallback.onFail();
            }
            return;
        }
        mEncorder.start();
        try {
            FileInputStream inputStream = new FileInputStream(mSrcFilePath);
            FileOutputStream mFileStream = new FileOutputStream(mDstFilePath);
            MediaCodec.BufferInfo mBufferInfo = new MediaCodec.BufferInfo();
            while(true) {
                long a = System.currentTimeMillis();
                // 從佇列中取出錄音的一幀音頻資料
                byte[] byteArray = new byte[2048];
                int readSize = inputStream.read(byteArray);
                if(readSize <= 0){
                    break;
                }
                ByteBuffer buf = ByteBuffer.wrap(byteArray);
                // 取出InputBuffer，填充音頻資料，然后輸送到編碼器進行編碼
                int inputBufferIndex = mEncorder.dequeueInputBuffer(0);
                if (inputBufferIndex >= 0) {
                    ByteBuffer inputBuffer = mEncorder.getInputBuffer(inputBufferIndex);
                    inputBuffer.clear();
                    inputBuffer.put(buf);
                    mEncorder.queueInputBuffer(inputBufferIndex, 0, readSize, System.nanoTime(), 0);
                }

                // 取出編碼好的一幀音頻資料，然后給這一幀添加ADTS頭
                int outputBufferIndex = mEncorder.dequeueOutputBuffer(mBufferInfo, 0);
                while (outputBufferIndex >= 0) {
                    ByteBuffer outputBuffer = mEncorder.getOutputBuffer(outputBufferIndex);
                    int outBufferSize = outputBuffer.limit() + 7;
                    byte[] aacBytes = new byte[outBufferSize];
                    addADTStoPacket(aacBytes, outBufferSize);
                    outputBuffer.get(aacBytes, 7, outputBuffer.limit());
                    mFileStream.write(aacBytes);

                    mEncorder.releaseOutputBuffer(outputBufferIndex, false);
                    outputBufferIndex = mEncorder.dequeueOutputBuffer(mBufferInfo, 0);
                }

                long b = System.currentTimeMillis() - a;
                Log.i("AudioEncode", "編碼耗時-毫秒==" + b);
            }
            if (mFileStream != null) {
                try {
                    mFileStream.flush();
                    mFileStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

            if (inputStream != null) {
                try {
                    mFileStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (mEncorder != null) {
                mEncorder.stop();
            }
            if(mCallback != null){
                mCallback.onSuccess();
            }
        } catch (FileNotFoundException e) {
            if(mCallback != null){
                mCallback.onFail();
            }
            e.printStackTrace();
        } catch (IOException e) {
            if(mCallback != null){
                mCallback.onFail();
            }
            e.printStackTrace();
        }
    }





    /**
     * Add ADTS header at the beginning of each and every AAC packet.
     * This is needed as MediaCodec encoder generates a packet of raw
     * AAC data.
     * <p>
     * Note the packetLen must count in the ADTS header itself !!! .
     * 注意，這里的packetLen引數為raw aac Packet Len + 7; 7 bytes adts header
     **/
    private void addADTStoPacket(byte[] packet, int packetLen) {
        int profile = 2;  //AAC LC，MediaCodecInfo.CodecProfileLevel.AACObjectLC;
        int freqIdx = 4;  //見后面注釋avpriv_mpeg4audio_sample_rates中32000對應的陣列下標，來自ffmpeg原始碼
        int chanCfg = 1;  //見后面注釋channel_configuration，AudioFormat.CHANNEL_IN_MONO 單聲道(聲道數量)

        /*int avpriv_mpeg4audio_sample_rates[] = {96000, 88200, 64000, 48000, 44100, 32000,24000, 22050, 16000, 12000, 11025, 8000, 7350};
        channel_configuration: 表示聲道數chanCfg
        0: Defined in AOT Specifc Config
        1: 1 channel: front-center
        2: 2 channels: front-left, front-right
        3: 3 channels: front-center, front-left, front-right
        4: 4 channels: front-center, front-left, front-right, back-center
        5: 5 channels: front-center, front-left, front-right, back-left, back-right
        6: 6 channels: front-center, front-left, front-right, back-left, back-right, LFE-channel
        7: 8 channels: front-center, front-left, front-right, side-left, side-right, back-left, back-right, LFE-channel
        8-15: Reserved
        */

        // fill in ADTS data
        packet[0] = (byte) 0xFF;
        //packet[1] = (byte)0xF9;
        packet[1] = (byte) 0xF1;//解決ios 不能播放問題
        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 void release(){
        if(mEncorder == null){
            return;
        }
        mEncorder.release();
        mEncorder = null;
    }
}

package com.yuanxuzhen.yuanrecord;

import android.content.Context;
import android.os.Environment;

import java.io.File;

public class DirUtil {
    public static final String WEBVIEW_CACHE = ".webviewCache";
    public static final String IMAGE_PATH = "image";
    public static final String DOWNLOAD_PATH = "download";
    public static final String VIDEO_PATH = ".video";
    public static final String NET_PATH = ".net";


    //image
    public static String getImageDir(Context context) {
        return getCacheDir(context) + File.separator + IMAGE_PATH;
    }

    //webview
    public static String getWebviewCache(Context context) {
        return getCacheDir(context) + File.separator + WEBVIEW_CACHE;
    }

    //download
    public static String getDownloadDir(Context context) {
        return getCacheDir(context) + File.separator + DOWNLOAD_PATH;
    }

    //video
    public static String getVideoPath(Context context) {
        return getCacheDir(context) + File.separator + VIDEO_PATH;
    }

    //net
    public static String getNetPath(Context context) {
        return getCacheDir(context) + File.separator + NET_PATH;
    }


    public static String getCacheDir(Context context) {
        if (context == null) {
            return "";
        }
        String path = null;
        if (context.getExternalCacheDir() != null
                && (Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())
                || !Environment.isExternalStorageRemovable())) {
            //外部存盤可用
            path = context.getExternalCacheDir().getPath();
        } else {
            //內部存盤不可用
            path = context.getCacheDir().getPath();
        }
        return path;
    }




}

package com.yuanxuzhen.yuanrecord;

public interface IHandlerCallback {
    void onSuccess(Object... object);

    void onFail(Object... object);
}

呼叫

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:orientation="vertical"
    android:paddingTop="100dp">


    <Button
        android:id="@+id/btnStart"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="start!"
        android:layout_gravity="center_horizontal"/>

    <Button
        android:id="@+id/btnPause"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="pause!"
        android:layout_gravity="center_horizontal"/>

    <Button
        android:id="@+id/btnStop"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="stop!"
        android:layout_gravity="center_horizontal"/>

    <Button
        android:id="@+id/encode_aac"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="encode pcm to aac "
        android:layout_gravity="center_horizontal"/>


</LinearLayout>

package com.yuanxuzhen.yuanrecord;

import android.app.Activity;
import android.media.AudioFormat;
import android.os.Build;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import androidx.annotation.RequiresApi;
import java.io.File;



public class Audio_Record extends Activity {
    private static final int RECORDER_SAMPLERATE = 44100;
    private static final int RECORDER_CHANNELS = AudioFormat.CHANNEL_IN_STEREO;
    private static final int RECORDER_AUDIO_ENCODING = AudioFormat.ENCODING_PCM_16BIT;
    private RecordAudio mRecorder;
    private EncodeAudioAAC mEncoder;
    private String pcmPath;
    private String aacPath;
    private Button btnStart;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_record);

        setButtonHandlers();
        btnStart = findViewById(R.id.btnStart);
        enableButton(R.id.btnStart, true);
        enableButton(R.id.btnPause, false);
        enableButton(R.id.btnStop, false);
        pcmPath = DirUtil.getCacheDir(this) + File.separator + "123.pcm";
        aacPath = DirUtil.getCacheDir(this) + File.separator + "123.aac";

        mRecorder = new RecordAudio();
        mRecorder.init(this, RECORDER_SAMPLERATE, RECORDER_CHANNELS, RECORDER_AUDIO_ENCODING, pcmPath);

        mEncoder = new EncodeAudioAAC();
        mEncoder.init(this,
                RECORDER_SAMPLERATE,
                mRecorder.getmChannelCount(),
                RECORDER_AUDIO_ENCODING,
                pcmPath,
                aacPath,
                new IHandlerCallback() {
                    @Override
                    public void onSuccess(Object... object) {
                        btnStart.post(new Runnable() {
                            @Override
                            public void run() {
                                Toast.makeText(Audio_Record.this, "解碼成功", Toast.LENGTH_SHORT).show();
                            }
                        });
                    }

                    @Override
                    public void onFail(Object... object) {
                        btnStart.post(new Runnable() {
                            @Override
                            public void run() {
                                Toast.makeText(Audio_Record.this, "解碼失敗", Toast.LENGTH_SHORT).show();
                            }
                        });
                    }
                });
    }

    private void setButtonHandlers() {
        ((Button) findViewById(R.id.btnStart)).setOnClickListener(btnClick);
        ((Button) findViewById(R.id.btnStop)).setOnClickListener(btnClick);
        ((Button) findViewById(R.id.btnPause)).setOnClickListener(btnClick);
        ((Button) findViewById(R.id.encode_aac)).setOnClickListener(btnClick);

    }

    private void enableButton(int id, boolean isEnable) {
        ((Button) findViewById(id)).setEnabled(isEnable);
    }


    private void enableButtons(RecordAudio.AUDIO_STAUS status) {
        if (status == RecordAudio.AUDIO_STAUS.START) {
            enableButton(R.id.btnStart, false);
            enableButton(R.id.btnPause, true);
            enableButton(R.id.btnStop, true);
        } else if (status == RecordAudio.AUDIO_STAUS.PAUSE) {
            enableButton(R.id.btnStart, true);
            enableButton(R.id.btnPause, false);
            enableButton(R.id.btnStop, true);
        } else if (status == RecordAudio.AUDIO_STAUS.STOP) {
            enableButton(R.id.btnStart, true);
            enableButton(R.id.btnPause, false);
            enableButton(R.id.btnStop, false);
        }

    }


    private View.OnClickListener btnClick = new View.OnClickListener() {
        @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
        public void onClick(View v) {
            switch (v.getId()) {
                case R.id.btnStart: {
                    Toast.makeText(Audio_Record.this, "開始錄制", Toast.LENGTH_SHORT).show();
                    mRecorder.startRecord();
                    enableButtons(mRecorder.mStatus);
                    break;
                }
                case R.id.btnPause: {
                    Toast.makeText(Audio_Record.this, "暫停錄制", Toast.LENGTH_SHORT).show();
                    mRecorder.pauseRecord();
                    enableButtons(mRecorder.mStatus);
                    break;
                }
                case R.id.btnStop: {
                    Toast.makeText(Audio_Record.this, "停止錄制", Toast.LENGTH_SHORT).show();
                    mRecorder.stopRecord();
                    enableButtons(mRecorder.mStatus);
                    break;
                }
                case R.id.encode_aac: {
                    Toast.makeText(Audio_Record.this, "開始轉碼", Toast.LENGTH_SHORT).show();
                    mEncoder.startEncording();
                    break;
                }
            }
        }
    };

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            finish();
        }
        return super.onKeyDown(keyCode, event);
    }

    @Override
    protected void onDestroy() {
        mRecorder.release();
        mEncoder.release();
        super.onDestroy();
    }
}