AudioRecord的用法

参考 http://www.cnblogs.com/renhui/p/7457321.html

1.计算缓冲录音数据的字节数组的大小。AudioRecord 需要一个容器来缓冲来自硬件的音频信息。

int recordBufSize = AudioRecord.getMinBufferSize(sampleRateInHz, channelConfig, audioFormat);      

2.创建AudioRecord对象

audioRecord = new AudioRecord(audioSource, sampleRateInHz, channelConfig, audioFormat, recordBufSize);      

3.创建数组对象

byte[] buffer = new byte[recordBufSize];      

4.开始录音

audioRecord.startRecording();      

5.在录音过程中来自硬件的数据写入缓冲数组

audioRecord.read(buffer, 0, recordBufSize);      

6.把数组的数据保存到文件

os = new FileOutputStream(pcmFileName);      

os.write(buffer);      

7.这样的音频文件还需要写入头部信息才能播放

8.代码实例如下

布局文件

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        android:padding="20dp"
        android:layout_margin="20dp"
        android:text="start"
        android:id="@+id/start"/>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_constraintLeft_toRightOf="@id/start"
        app:layout_constraintTop_toTopOf="parent"
        android:padding="20dp"
        android:layout_margin="20dp"
        android:text="stop"
        android:id="@+id/stop"/>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toBottomOf="@id/start"
        android:padding="20dp"
        android:layout_margin="20dp"
        android:text="transform"
        android:id="@+id/transform"/>

</android.support.constraint.ConstraintLayout>
           

activity文件

public class MainActivity extends AppCompatActivity {


    // 音频源：音频输入-麦克风
    private final static int AUDIO_INPUT = MediaRecorder.AudioSource.MIC;

    // 采样率
    // 44100是目前的标准，但是某些设备仍然支持22050，16000，11025
    // 采样频率一般共分为22.05KHz、44.1KHz、48KHz三个等级
    private final static int AUDIO_SAMPLE_RATE = 16000;

    // 音频通道 单声道
    private final static int AUDIO_CHANNEL = AudioFormat.CHANNEL_IN_MONO;

    // 音频格式：PCM编码
    private final static int AUDIO_ENCODING = AudioFormat.ENCODING_PCM_16BIT;

    /**
     * 需要申请的运行时权限
     */
    private String[] permissions = new String[]{
            Manifest.permission.RECORD_AUDIO,
            Manifest.permission.READ_EXTERNAL_STORAGE,
            Manifest.permission.WRITE_EXTERNAL_STORAGE
    };


    private static final int MY_PERMISSIONS_REQUEST = 1001;
    private final String pcmFileName = Environment.getExternalStorageDirectory() + "/Download/record.pcm";
    private final String wavFileName = Environment.getExternalStorageDirectory() + "/Download/record.wav";
    private AudioRecord audioRecord = null;  // 声明 AudioRecord 对象
    private int recordBufSize = 0; // 声明recoordBufffer的大小字段
    private byte[] buffer;
    private boolean isRecording;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ActivityCompat.requestPermissions(this, permissions, MY_PERMISSIONS_REQUEST);

        findViewById(R.id.start).setOnClickListener(v -> start());

        findViewById(R.id.stop).setOnClickListener(v -> stop());

        findViewById(R.id.transform).setOnClickListener(v -> Pcm2WavUtil.pcmToWav(AUDIO_SAMPLE_RATE, AUDIO_CHANNEL,
                recordBufSize, pcmFileName, wavFileName));

    }

    private void stop(){
        isRecording = false;

        if (null != audioRecord) {
            audioRecord.stop();
            audioRecord.release();
            audioRecord = null;
        }
    }

    private void start(){

        //audioRecord能接受的最小的buffer大小
        recordBufSize = AudioRecord.getMinBufferSize(AUDIO_SAMPLE_RATE, AUDIO_CHANNEL, AUDIO_ENCODING);
        audioRecord = new AudioRecord(AUDIO_INPUT, AUDIO_SAMPLE_RATE, AUDIO_CHANNEL, AUDIO_ENCODING, recordBufSize);
        buffer = new byte[recordBufSize];

        audioRecord.startRecording();
        isRecording = true;

        new Thread(() -> {
            FileOutputStream os = null;

            try {
                if(!new File(pcmFileName).exists()){
                    new File(pcmFileName).createNewFile();
                }
                os = new FileOutputStream(pcmFileName);
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }

            if (null != os) {
                while (isRecording) {
                    int read = audioRecord.read(buffer, 0, recordBufSize);

                    // 如果读取音频数据没有出现错误，就将数据写入到文件
                    if (AudioRecord.ERROR_INVALID_OPERATION != read) {
                        try {
                            os.write(buffer);
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }

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

}
           

转wav的工具文件

public class Pcm2WavUtil {


    /**
     * pcm文件转wav文件
     *
     * @param inFilename 源文件路径
     * @param outFilename 目标文件路径
     */
    public static void pcmToWav(long mSampleRate, int mChannel, int mBufferSize, String inFilename, String outFilename) {
        FileInputStream in;
        FileOutputStream out;
        long totalAudioLen;
        long totalDataLen;
        long longSampleRate = mSampleRate;
        int channels = mChannel == AudioFormat.CHANNEL_IN_MONO ? 1 : 2;
        long byteRate = 16 * mSampleRate * channels / 8;
        byte[] data = new byte[mBufferSize];
        try {
            in = new FileInputStream(inFilename);
            out = new FileOutputStream(outFilename);
            totalAudioLen = in.getChannel().size();
            totalDataLen = totalAudioLen + 36;

            writeWaveFileHeader(out, totalAudioLen, totalDataLen,
                    longSampleRate, channels, byteRate);
            while (in.read(data) != -1) {
                out.write(data);
            }
            in.close();
            out.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }


    /**
     * 加入wav文件头
     */
    private static void writeWaveFileHeader(FileOutputStream out, long totalAudioLen,
                                     long totalDataLen, long longSampleRate, int channels, long byteRate)
            throws IOException {
        byte[] header = new byte[44];
        // RIFF/WAVE header
        header[0] = 'R';
        header[1] = 'I';
        header[2] = 'F';
        header[3] = 'F';
        header[4] = (byte) (totalDataLen & 0xff);
        header[5] = (byte) ((totalDataLen >> 8) & 0xff);
        header[6] = (byte) ((totalDataLen >> 16) & 0xff);
        header[7] = (byte) ((totalDataLen >> 24) & 0xff);
        //WAVE
        header[8] = 'W';
        header[9] = 'A';
        header[10] = 'V';
        header[11] = 'E';
        // 'fmt ' chunk
        header[12] = 'f';
        header[13] = 'm';
        header[14] = 't';
        header[15] = ' ';
        // 4 bytes: size of 'fmt ' chunk
        header[16] = 16;
        header[17] = 0;
        header[18] = 0;
        header[19] = 0;
        // format = 1
        header[20] = 1;
        header[21] = 0;
        header[22] = (byte) channels;
        header[23] = 0;
        header[24] = (byte) (longSampleRate & 0xff);
        header[25] = (byte) ((longSampleRate >> 8) & 0xff);
        header[26] = (byte) ((longSampleRate >> 16) & 0xff);
        header[27] = (byte) ((longSampleRate >> 24) & 0xff);
        header[28] = (byte) (byteRate & 0xff);
        header[29] = (byte) ((byteRate >> 8) & 0xff);
        header[30] = (byte) ((byteRate >> 16) & 0xff);
        header[31] = (byte) ((byteRate >> 24) & 0xff);
        // block align
        header[32] = (byte) (2 * 16 / 8);
        header[33] = 0;
        // bits per sample
        header[34] = 16;
        header[35] = 0;
        //data
        header[36] = 'd';
        header[37] = 'a';
        header[38] = 't';
        header[39] = 'a';
        header[40] = (byte) (totalAudioLen & 0xff);
        header[41] = (byte) ((totalAudioLen >> 8) & 0xff);
        header[42] = (byte) ((totalAudioLen >> 16) & 0xff);
        header[43] = (byte) ((totalAudioLen >> 24) & 0xff);
        out.write(header, 0, 44);
    }

}