安卓AudioRecord示例

Question

我正在设计一个安卓应用，需要使用AudioRecord类来录制用户的声音。经过一些研究（没有提供足够的信息）和几次失败尝试后，我想知道是否有人能够帮我发布一个如何使用AudioRecord捕获高质量声音的示例代码。非常感谢。谢谢

- Ziki Kongawi

Answer 1

我在这里向您发布一些代码示例，使用 AudioRecord API 记录高质量的声音。

注意：如果您在模拟器中使用，声音质量不会很好，因为我们使用的采样率为8k，仅支持模拟器。在设备上使用采样率44.1k以获得更好的质量。

public class Audio_Record extends Activity {
    private static final int RECORDER_SAMPLERATE = 8000;
    private static final int RECORDER_CHANNELS = AudioFormat.CHANNEL_IN_MONO;
    private static final int RECORDER_AUDIO_ENCODING = AudioFormat.ENCODING_PCM_16BIT;
    private AudioRecord recorder = null;
    private Thread recordingThread = null;
    private boolean isRecording = false;

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

        setButtonHandlers();
        enableButtons(false);

        int bufferSize = AudioRecord.getMinBufferSize(RECORDER_SAMPLERATE,
                RECORDER_CHANNELS, RECORDER_AUDIO_ENCODING); 
    }

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

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

    private void enableButtons(boolean isRecording) {
        enableButton(R.id.btnStart, !isRecording);
        enableButton(R.id.btnStop, isRecording);
    }

    int BufferElements2Rec = 1024; // want to play 2048 (2K) since 2 bytes we use only 1024
    int BytesPerElement = 2; // 2 bytes in 16bit format

    private void startRecording() {

        recorder = new AudioRecord(MediaRecorder.AudioSource.MIC,
                RECORDER_SAMPLERATE, RECORDER_CHANNELS,
                RECORDER_AUDIO_ENCODING, BufferElements2Rec * BytesPerElement);

        recorder.startRecording();
        isRecording = true;
        recordingThread = new Thread(new Runnable() {
            public void run() {
                writeAudioDataToFile();
            }
        }, "AudioRecorder Thread");
        recordingThread.start();
    }

        //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;

    }

    private void writeAudioDataToFile() {
        // Write the output audio in byte

        String filePath = "/sdcard/voice8K16bitmono.pcm";
        short sData[] = new short[BufferElements2Rec];

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

        while (isRecording) {
            // gets the voice output from microphone to byte format

            recorder.read(sData, 0, BufferElements2Rec);
            System.out.println("Short writing to file" + sData.toString());
            try {
                // // writes the data to file from buffer
                // // stores the voice buffer
                byte bData[] = short2byte(sData);
                os.write(bData, 0, BufferElements2Rec * BytesPerElement);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        try {
            os.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private void stopRecording() {
        // stops the recording activity
        if (null != recorder) {
            isRecording = false;
            recorder.stop();
            recorder.release();
            recorder = null;
            recordingThread = null;
        }
    }

    private View.OnClickListener btnClick = new View.OnClickListener() {
        public void onClick(View v) {
            switch (v.getId()) {
            case R.id.btnStart: {
                enableButtons(true);
                startRecording();
                break;
            }
            case R.id.btnStop: {
                enableButtons(false);
                stopRecording();
                break;
            }
            }
        }
    };

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

要获取更详细信息，请查看AUDIORECORD BLOG。

- Rahul Baradia

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我可以问一下数据写入outputstream的频率吗？还有为什么要读取shorts，API不提供读取bytes的选项吗？ - james

@JamesClark 取决于您发送到服务器的大小。如果您发送音频数据1024个shorts，即2048字节。那么您必须在40毫秒内发送到服务器。您也可以以字节读取，这并没有太大区别。 - Rahul Baradia

此外，44100 是唯一保证在所有设备上都支持的采样率。 http://developer.android.com/reference/android/media/AudioRecord.html - Christopher Schneider

请注意此解决方案，因为它截断音频样本数为1024，如果大小不是1024的倍数，则会导致录制音频失真。应使用“AudioRecord.getMinBufferSize”返回的大小。同时调用“short2byte”是不必要的。 - us_david

BufferElements2Rec和BytesPerElement是什么？请问我如何得到这些值？我是Android音频录制的新手，目前正在苦苦挣扎。拜托了。 - Wai Yan Hein

Answer 2

我为Android麦克风音频流传输到服务器进行播放实现了端到端解决方案：Android AudioRecord to Server over UDP Playback Issues

- Joshua W

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好代码！它解决了我的下一个问题。+1 - Mahdi Moqadasi