Android Audio——使用AudioRecord录制音频

一、android平台上的音频采集

Android SDK 提供了两套音频采集的API，分别是：MediaRecorder 和 AudioRecord，前者是一个更加上层一点的 API，它可以直接把手机麦克风录入的音频数据进行编码压缩（如 AMR、MP3 等）并存成文件，而后者则更接近底层，能够更加自由灵活地控制，可以得到原始的一帧帧 PCM 音频数据。

二、AudioRecord音频采集的基本流程

1. 构造一个 AudioRecord 对象。

2. 开始采集。

3. 读取采集的数据。

4. 停止采集。

三、AudioRecord的基本参数

•  audioSource 音频采集的来源，参考MediaRecorder.AudioSource

•  sampleRateInHz 音频采样率

•  channelConfig 声道，CHANNEL_IN_MONO（单声道），CHANNEL_IN_STEREO（双声道）

•  audioFormat 音频采样精度，指定采样的数据的格式和每次采样的大小

•  bufferSizeInBytes AudioRecord 采集到的音频数据所存放的缓冲区大小

四、AudioRecord类的主要方法

五、代码实现

1）权限

<uses-permission android:name="android.permission.RECORD_AUDIO" />

2）AudioRecord 类的接口简单封装

public class AudioCapturer {
    private static final String TAG = "AudioCapturer";
 
 
    private static final int DEFAULT_SOURCE = MediaRecorder.AudioSource.MIC;
    private static final int DEFAULT_SAMPLE_RATE = 44100;
    private static final int DEFAULT_CHANNEL_CONFIG = AudioFormat.CHANNEL_IN_STEREO;
    private static final int DEFAULT_AUDIO_FORMAT = AudioFormat.ENCODING_PCM_16BIT;
 
 
    private AudioRecord mAudioRecord;
    private int mMinBufferSize = 0;
    private Thread mCaptureThread;
    private boolean mIsCaptureStarted = false;
    private volatile boolean mIsLoopExit = false;
    private OnAudioFrameCapturedListener mAudioFrameCapturedListener;
 
 
    public interface OnAudioFrameCapturedListener {
        public void onAudioFrameCaptured(byte[] audioData);
    }
 
 
    public boolean isCaptureStarted() {
        return mIsCaptureStarted;
    }
 
 
    public void setOnAudioFrameCapturedListener(OnAudioFrameCapturedListener listener) {
        mAudioFrameCapturedListener = listener;
    }
 
 
    public boolean startCapture() {
        return startCapture(DEFAULT_SOURCE, DEFAULT_SAMPLE_RATE, DEFAULT_CHANNEL_CONFIG,
                DEFAULT_AUDIO_FORMAT);
    }
 
 
    @SuppressLint("MissingPermission")
    public boolean startCapture(int audioSource, int sampleRateInHz, int channelConfig, int audioFormat) {
        if (mIsCaptureStarted) {
            Log.e(TAG, "Capture already started !");
            return false;
        }
 
 
        mMinBufferSize = AudioRecord.getMinBufferSize(sampleRateInHz,channelConfig,audioFormat);
        if (mMinBufferSize == AudioRecord.ERROR_BAD_VALUE) {
            Log.e(TAG, "Invalid parameter !");
            return false;
        }
        Log.d(TAG , "getMinBufferSize = "+mMinBufferSize+" bytes !");
        mAudioRecord = new AudioRecord(audioSource,sampleRateInHz,channelConfig,audioFormat,mMinBufferSize);
        if (mAudioRecord.getState() == AudioRecord.STATE_UNINITIALIZED) {
            Log.e(TAG, "AudioRecord initialize fail !");
            return false;
        }
 
 
        mAudioRecord.startRecording();
        mIsLoopExit = false;
        mCaptureThread = new Thread(new AudioCaptureRunnable());
        mCaptureThread.start();
        mIsCaptureStarted = true;
        Log.d(TAG, "Start audio capture success !");
        return true;
    }
 
 
    public void stopCapture() {
        if (!mIsCaptureStarted) {
            return;
        }
        mIsLoopExit = true;
        try {
            mCaptureThread.interrupt();
            mCaptureThread.join(1000);
        }
        catch (InterruptedException e) {
            e.printStackTrace();
        }
        if (mAudioRecord.getRecordingState() == AudioRecord.RECORDSTATE_RECORDING) {
            mAudioRecord.stop();
        }
        mAudioRecord.release();
        mIsCaptureStarted = false;
        mAudioFrameCapturedListener = null;
        Log.d(TAG, "Stop audio capture success !");
    }
 
 
    private class AudioCaptureRunnable implements Runnable {
        @Override
        public void run() {
            while (!mIsLoopExit) {
                byte[] buffer = new byte[mMinBufferSize];
                int ret = mAudioRecord.read(buffer, 0, mMinBufferSize);
                if (ret == AudioRecord.ERROR_INVALID_OPERATION) {
                    Log.e(TAG , "Error ERROR_INVALID_OPERATION");
                }
                else if (ret == AudioRecord.ERROR_BAD_VALUE) {
                    Log.e(TAG , "Error ERROR_BAD_VALUE");
                }
                else {
                    if (mAudioFrameCapturedListener != null) {
                        mAudioFrameCapturedListener.onAudioFrameCaptured(buffer);
                    }
                    Log.d(TAG , "OK, Captured "+ret+" bytes !");
                }
                SystemClock.sleep(10);
            }
        }
    }
}