Android 中的音频录制和流式传输答案

【问题标题】：Audio Recording and Streaming in AndroidAndroid 中的音频录制和流式传输
【发布时间】：2014-11-04 23:17:51
【问题描述】：

我正在开发一个安卓应用程序。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。

【问题讨论】：

录制时，是在文件中录制还是在临时Buffer中录制？

标签： android audio-streaming audio-recording

【解决方案1】：

这是一个简单的录制和播放应用程序。
使用安卓AudioRecord和AudioTrack，

设计：

录制的音频被写入缓冲区并从同一个缓冲区播放，该机制在按钮控制的循环中运行（使用 Android 线程）。

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;
        }
    }
}

启动线程：

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

AudioRecord和AudioTrack的初始化方法：

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 的值可能因设备而异。
请参考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 API 从文件中写入/读取来实现。
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。同样适用于findAudioRecord 和findAudioTrack。

【讨论】：

【解决方案2】：

首先在 onCreate 方法中创建对象，MediaRecorder 类对象以及要保存录制数据的文件路径。

  String outputFile = Environment.getExternalStorageDirectory().
  getAbsolutePath() + "/myrecording.3gp";   // Define outputFile outside onCreate method

  MediaRecorder myAudioRecorder = new MediaRecorder(); // Define this outside onCreate method

  myAudioRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
  myAudioRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
  myAudioRecorder.setAudioEncoder(MediaRecorder.OutputFormat.AMR_NB);
  myAudioRecorder.setOutputFile(outputFile);

这三个函数你可以在任何按钮上调用它，以播放Rec、停止Rec和开始Rec；

  public void start(View view){
  try {
     myAudioRecorder.prepare();
     myAudioRecorder.start();
   } catch (IllegalStateException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
   } catch (IOException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
   }
   start.setEnabled(false);
   stop.setEnabled(true);
   Toast.makeText(getApplicationContext(), "Recording started", Toast.LENGTH_LONG).show();
  }

  public void stop(View view){

    myAudioRecorder.stop();
    myAudioRecorder.release();
    myAudioRecorder  = null;
    stop.setEnabled(false);
    play.setEnabled(true);
    Toast.makeText(getApplicationContext(), "Audio recorded successfully",
    Toast.LENGTH_LONG).show();
   }



  public void play(View view) throws IllegalArgumentException,   

    SecurityException, IllegalStateException, IOException{
    MediaPlayer m = new MediaPlayer();
    m.setDataSource(outputFile);
    m.prepare();
    m.start();
    Toast.makeText(getApplicationContext(), "Playing audio", Toast.LENGTH_LONG).show();

    }

【讨论】：

【解决方案3】：

当我阅读开发者文档here 时，Android 支持 RTSP 协议（用于实时流式传输）以及 HTTP/HTTPS 实时流式传输协议草案。

还有一个例子here。您必须具备有关流媒体服务器的基础知识，例如 Red5 或 Wowza。

【讨论】：