Metronome Timer slowdown (via Handler, or Threads too)

Question

I have a simple, classic, statement that every 200 milliseconds plays a sound (a metronome).

I wrote it using Handlers, and then in another way, using Threads. The problem is the same in both ways: when I press hardware home button, or also simply when I press a button to open a ListView, the metronome terribly slowdown for a while.

This problem (not so strong, but however present) presents also doing nothing and leaving the application in foreground.

Any ideas?

Here's the code:

public class Metronome implements Runnable{

private Handler mHandler = new Handler();
public static long mStartTime;

Main mainContext; 

public Metronomo(Main context) {
    mainContext = context;
}


public void play() {
    mStartTime = System.currentTimeMillis();
    mHandler.postDelayed(this, 100);
}

public final void stop(){
    mHandler.removeCallbacks(this);
}

public void run(){
        //play the ogg file in position 1
        mSoundManager.playSound(1);

        //reschedule the next playing after 200ms
        mHandler.postAtTime(this, SystemClock.uptimeMillis() + 200);
   }

};

Answer 1

Hi. Are you using some kind of pause statement to wait between beats? You could try basing the timing on multiples of a system clock value instead. That way you may still get beats that occur late (or not at all) but you wouldn't get a slow down. Hope that makes some kind of sense.

This is more of a comment but I don't have enough rep to leave comments just yet.

Answer 2

My phone seems to be able to play midi files, which are a pretty compact way to represent sound, perhaps you could dynamically create one and use that for the metronome? I'm assuming that the synthesis is handled at a lower level than would ordinarily be accessible to you so that the timing would be better, but I don't know that for a fact.