Question

I got 0.3-0.5 sec latency while record audio (live monitoring). Here’s my code:

code from here: Android – Getting audio to play through earpiece

public class Sounds extends Activity {

private boolean isRecording;
private AudioManager am;
private int count;

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

    am = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
    am.setMicrophoneMute(true);

    while(count <= 1000000){
    Record record = new Record();  
    record.run();
    count ++;
    Log.d("COUNT", "Count is : " + count);
    }
}

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_MUSIC,
                                        11025,
                                        AudioFormat.CHANNEL_CONFIGURATION_MONO,
                                        AudioFormat.ENCODING_PCM_16BIT,
                                        buffersize,
                                        AudioTrack.MODE_STREAM);


                        am.setRouting(AudioManager.MODE_NORMAL,1,
                          AudioManager.STREAM_MUSIC);


                        int ok = am.getRouting(AudioManager.ROUTE_EARPIECE);
                        Log.d("ROUTING", "getRouting = " + ok);
                        setVolumeControlStream(AudioManager.STREAM_VOICE_CALL);
                        //am.setSpeakerphoneOn(true);
                        Log.d("SPEAKERPHONE", "Is speakerphone on? : " + am.isSpeakerphoneOn());
                        am.setSpeakerphoneOn(false);
                        Log.d("SPEAKERPHONE", "Is speakerphone on? : " + am.isSpeakerphoneOn());
                        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;
        }
} 

}

Can you help me? (sorry for my english)

Answer 1

From my understanding, you’re wanting to achieve lower latency? If so, it’s currently an issue with the Android OS that audio latency can be fairly high, which is why you don’t see many real-time audio apps in the marketplace. The Android 4.0 spec allows for low-latency audio, but until then, that may be speedy as you’ll get.

Ref Section 5.4:
http://static.googleusercontent.com/external_content/untrusted_dlcp/source.android.com/en/us/compatibility/4.0/android-4.0-cdd.pdf