Question

我正在尝试使用AudioRecord和AudioTrack将在MIC上获得的音频样本传递给扬声器。这是代码：

public class MainActivity extends Activity {
    AudioManager am = null;
    AudioRecord record =null;
    AudioTrack track =null;
    final int SAMPLE_FREQUENCY = 44100;
    final int SIZE_OF_RECORD_ARRAY = 1024;  // 1024 ORIGINAL
    final int WAV_SAMPLE_MULTIPLICATION_FACTOR = 1;
    int i= 0;
    boolean isPlaying = true;
    class MyThread extends Thread{
        private volatile boolean passThroughMode = true;
        // /*
        MyThread(){
            super();
        }

        MyThread(boolean newPTV){
            this.passThroughMode = newPTV;
        }
        // */

        // /*
        @Override
        public void run(){
            short[] lin = new short[SIZE_OF_RECORD_ARRAY];
            int num = 0;
            // am = (AudioManager) this.getSystemService(Context.AUDIO_SERVICE); // -> MOVED THESE TO init()
            // am.setMode(AudioManager.MODE_IN_COMMUNICATION);
            record.startRecording();
            track.play();
            while (passThroughMode) {
            // while (!isInterrupted()) {
                num = record.read(lin, 0, SIZE_OF_RECORD_ARRAY);
                for(i=0;i<lin.length;i++)
                    lin[i] *= WAV_SAMPLE_MULTIPLICATION_FACTOR; 
                track.write(lin, 0, num);
            }
            // /*
            record.stop();
            track.stop();
            record.release();
            track.release();
            // */
        }
        // */

        // /*
        public void stopThread(){
            passThroughMode = false;
        }
        // */
    }

    MyThread newThread;

    private void init() {
        int min = AudioRecord.getMinBufferSize(SAMPLE_FREQUENCY, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT);
        record = new AudioRecord(MediaRecorder.AudioSource.VOICE_COMMUNICATION, SAMPLE_FREQUENCY, AudioFormat.CHANNEL_IN_MONO,
                                 AudioFormat.ENCODING_PCM_16BIT, min);
        int maxJitter = AudioTrack.getMinBufferSize(SAMPLE_FREQUENCY, AudioFormat.CHANNEL_OUT_MONO, AudioFormat.ENCODING_PCM_16BIT);
        track = new AudioTrack(AudioManager.MODE_IN_COMMUNICATION, SAMPLE_FREQUENCY, AudioFormat.CHANNEL_OUT_MONO,
                               AudioFormat.ENCODING_PCM_16BIT, maxJitter, AudioTrack.MODE_STREAM);
        am = (AudioManager) this.getSystemService(Context.AUDIO_SERVICE);
        am.setMode(AudioManager.MODE_IN_COMMUNICATION);

    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        setVolumeControlStream(AudioManager.MODE_IN_COMMUNICATION);
        // init(); // -> Moved this to onResume();
        Log.d("MYLOG", "onCreate() called");
    }

    @Override
    protected void onResume(){
        super.onResume();
        // newThread.stopThread();
        Log.d("MYLOG", "onResume() called");
        init();
        newThread = new MyThread(true);
        newThread.start(); 
    }

    @Override
    protected void onPause(){
        super.onPause();
        Log.d("MYLOG", "onPause() called");
        newThread.stopThread();
        // android.os.Process.killProcess(android.os.Process.myPid());
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    public void passStop(View view){
        Button playBtn = (Button) findViewById(R.id.playBtn);  
        // /*
        if(!isPlaying){
            record.startRecording();
            track.play();
            isPlaying = true;
            playBtn.setText("Pause");
        }
        else{
           record.stop();
           track.pause();
           isPlaying=false;
           playBtn.setText("Pass through");
        }
        // */
    }

    // /*
    @Override
    protected void onDestroy() {
        super.onDestroy();
        newThread.stopThread();
        // android.os.Process.killProcess(android.os.Process.myPid());
        // killProcess(android.os.Process.myPid());
        // newThread.interrupt();
         Log.d("MYLOG", "onDestroy() called");
    }
    // */
}

该程序应该启动一个执行传递的线程。线程从应用程序的onResume（）开始，所以应立即启动。但是开始时总是有1.5~2秒的延迟。我假设它可能是因为onCreate（）和其他初始化发生在线程在onResume（）之前启动，但如果我打印出lin数组的内容到文件，它总是写一个0的长行在开头，表示延迟可能不是由于初始化所需的时间。那么这里的延迟是什么？ track.play（）需要很长时间才能开始播放吗？

Answer 1

我正在调试类似的延迟，虽然我还没有完整的答案，但似乎AudioManager在setMode调用中引入了延迟（am.setMode（AudioManager.MODE_IN_COMMUNICATION））。

在Android上初始化AudioTrack有任何明显的延迟吗？

1 个答案: