android - Android 中的音频录制和流式传输

Question

我正在开发一个 Android 应用程序。我想完成以下功能。我将使用手机的内置麦克风进行录音，同时我希望通过手机的扬声器或耳机播放录制的音频。可行吗？如果是，请帮助我。

Answer 1

这是一个简单的录音和回放应用程序。
使用 Android AudioRecord和 AudioTrack ,

Design:

The recorded audio is written to a buffer and played back from the same buffer, This mechanism runs in a loop (using Android thread) controlled by buttons.

---

代码

private String TAG = "AUDIO_RECORD_PLAYBACK";
private boolean isRunning = true;
private Thread m_thread;               /* Thread for running the Loop */

private AudioRecord recorder = null;
private AudioTrack track = null;

int bufferSize = 320;                  /* Buffer for recording data */
byte buffer[] = new byte[bufferSize];

/* Method to Enable/Disable Buttons */
private void enableButton(int id,boolean isEnable){
    ((Button)findViewById(id)).setEnabled(isEnable);
}

---

GUI 有两个按钮START 和STOP。
启用按钮:

enableButton(R.id.StartButton,true);
enableButton(R.id.StopButton,false);

/* Assign Button Click Handlers */
((Button)findViewById(R.id.StartButton)).setOnClickListener(btnClick);
((Button)findViewById(R.id.StopButton)).setOnClickListener(btnClick);

---

为 OnClickListener 映射开始和停止按钮

private View.OnClickListener btnClick = new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        switch(v.getId()){
        case R.id.StartButton:
        {
            Log.d(TAG, "======== Start Button Pressed ==========");
            isRunning = true;
            do_loopback(isRunning);
            enableButton(R.id.StartButton,false);
            enableButton(R.id.StopButton,true);
            break;
        }
        case R.id.StopButton:
        {
            Log.d(TAG, "======== Stop Button Pressed ==========");
            isRunning = false;
            do_loopback(isRunning);
            enableButton(R.id.StopButton,false);
            enableButton(R.id.StartButton,true);
            break;
        }
    }
}

---

开始线程:

private void do_loopback(final boolean flag) 
{
    m_thread = new Thread(new Runnable() {
        public void run() {
            run_loop(flag);
        }
    });
    m_thread.start();
}

---

初始化AudioRecord和AudioTrack的方法:

public AudioTrack findAudioTrack (AudioTrack track)
{
    Log.d(TAG, "===== Initializing AudioTrack API ====");
    int m_bufferSize = AudioTrack.getMinBufferSize(8000, 
            AudioFormat.CHANNEL_OUT_MONO, 
            AudioFormat.ENCODING_PCM_16BIT);

    if (m_bufferSize != AudioTrack.ERROR_BAD_VALUE) 
    {
        track = new AudioTrack(AudioManager.STREAM_MUSIC, 8000, 
                AudioFormat.CHANNEL_OUT_MONO, 
                AudioFormat.ENCODING_PCM_16BIT, m_bufferSize, 
                AudioTrack.MODE_STREAM);

        if (track.getState() == AudioTrack.STATE_UNINITIALIZED) {
            Log.e(TAG, "===== AudioTrack Uninitialized =====");
            return null;
        }
    }
    return track;
}

public AudioRecord findAudioRecord (AudioRecord recorder)
{
    Log.d(TAG, "===== Initializing AudioRecord API =====");     
    int m_bufferSize = AudioRecord.getMinBufferSize(8000,
            AudioFormat.CHANNEL_IN_MONO,
            AudioFormat.ENCODING_PCM_16BIT);

    if (m_bufferSize != AudioRecord.ERROR_BAD_VALUE) 
    {
        recorder = new AudioRecord(MediaRecorder.AudioSource.MIC, 8000, 
                AudioFormat.CHANNEL_IN_MONO,
                AudioFormat.ENCODING_PCM_16BIT, m_bufferSize);

        if (recorder.getState() == AudioRecord.STATE_UNINITIALIZED) {
            Log.e(TAG, "====== AudioRecord UnInitilaised ====== ");
            return null;
        }
    }
    return recorder;
}

findAudioRecord 或 findAudioTrack 的值可以根据设备更改。
请引用this问题。

---

运行循环的代码:

public void run_loop (boolean isRunning)
{

    /** == If Stop Button is pressed == **/
    if (isRunning == false) {
        Log.d(TAG, "=====  Stop Button is pressed ===== ");
        
        if (AudioRecord.STATE_INITIALIZED == recorder.getState()){
            recorder.stop();
            recorder.release();
        }
        if (AudioTrack.STATE_INITIALIZED == track.getState()){
            track.stop();
            track.release();
        }
        return;
    }
    

    /** ======= Initialize AudioRecord and AudioTrack ======== **/
    recorder = findAudioRecord(recorder);
    if (recorder == null) {
        Log.e(TAG, "======== findAudioRecord : Returned Error! =========== ");
        return;
    }

    track = findAudioTrack(track);
    if (track == null) {
        Log.e(TAG, "======== findAudioTrack : Returned Error! ========== ");
        return;
    }

    if ((AudioRecord.STATE_INITIALIZED == recorder.getState()) &&
            (AudioTrack.STATE_INITIALIZED == track.getState()))
    {
        recorder.startRecording();
        Log.d(TAG, "========= Recorder Started... =========");
        track.play();
        Log.d(TAG, "========= Track Started... =========");
    } 
    else 
    {
        Log.d(TAG, "==== Initilazation failed for AudioRecord or AudioTrack =====");
        return;
    }

    /** ------------------------------------------------------ **/

    /* Recording and Playing in chunks of 320 bytes */
    bufferSize = 320;
    
    while (isRunning == true) 
    {
        /* Read & Write to the Device */
        recorder.read(buffer, 0, bufferSize);
        track.write(buffer, 0, bufferSize);

    }
    Log.i(TAG, "Loopback exit");
    return;
}

---

请在 AndroidManifest.xml 中包含以下内容

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

上述过程也可以通过使用相同的 API 写入/读取文件来实现。
为什么使用 audioRecord 而不是 mediaRecorder - See here .

代码已经过测试(在 Google Nexus 5 上)并且运行良好。

注意:请为recorder.read和track.write添加一些错误检查代码，以防失败。这同样适用于 findAudioRecord 和 findAudioTrack。