android - Android 麦克风到扬声器直接流媒体应用程序的音频延迟

Question

我正在尝试构建一个麦克风应用程序，麦克风的声音直接由扬声器播放。问题是听到的声音有延迟。代码如下。有没有办法避免这种延迟？我听说我们可以通过在c/c++中添加 native 代码然后从java调用它来避免这种情况。是否可以？如果是这样怎么办？

public class MainActivity extends AppCompatActivity {
    boolean isRecording; 
    AudioManager am;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        am = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
        Record record = new Record();
        record.run();

    }
    public class Record extends Thread
    {

        static final int bufferSize = 200000;
        final short[] buffer = new short[bufferSize];
        short[] readBuffer = new short[bufferSize];

        public void run() {
            isRecording = true;
            android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_URGENT_AUDIO);
            int buffersize = AudioRecord.getMinBufferSize(11025,AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_16BIT);
            AudioRecord arec = new AudioRecord(MediaRecorder.AudioSource.MIC, 11025, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_16BIT,buffersize);
            AudioTrack atrack = new AudioTrack(AudioManager.STREAM_VOICE_CALL, 11025, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_16BIT, buffersize, AudioTrack.MODE_STREAM);
            am.setRouting(AudioManager.MODE_NORMAL, AudioManager.ROUTE_EARPIECE, AudioManager.ROUTE_ALL);
            atrack.setPlaybackRate(11025);
            byte[] buffer = new byte[buffersize];
            arec.startRecording();
            atrack.play();
            while(isRecording) {
                arec.read(buffer, 0,
                        buffersize);
                atrack.write(buffer, 0,
                        buffer.length);
            }
            arec.stop();
            atrack.stop();
            isRecording = false;
        }
    }
}

Answer 1

使用此类在 Android 上设置 native 音频:https://github.com/superpoweredSDK/Low-Latency-Android-Audio-iOS-Audio-Engine/tree/master/Superpowered/AndroidIO

您也可以在那里找到示例项目。