title: Convert time in microseconds to minutes and seconds
body: <p>My iPhone app uses FFMPeg for decoding/playing an audio file.</p>
  
  <p>I'm successfully getting the current time in microseconds from the appropriate FFMPeg function, but I'm not being able to convert it to minutes and seconds (MM:SS).</p>
  
  <p>This is my code to display an <code>NSString</code> containing the time; <code>getFFMPEGtime</code> is the time in microseconds:</p>
  
  <pre><code> self.currentAudioTime = [NSString stringWithFormat: @"%02d:%02d",
                                  (int) getFFMPEGtime / (int)1000000,
                                  (int) getFFMPEGtime % 1000000];
  </code></pre>
  
  <p>It seems that the time in minutes is okay, but the seconds are messed up. What's the proper way to convert microseconds to minutes and seconds?         </p>