title: Amplifying playback volume from a local AMR file
body: <p>I have an application that plays back AMR audio files that it has downloaded and cached locally.<br>
  This works fine &mdash; the basic <a href="http://developer.android.com/reference/android/media/MediaPlayer.html" rel="noreferrer"><code>MediaPlayer</code></a> does its job.</p>
  
  <p>However, the audio volume is generally very low, and manually increasing the volume with the hardware keys still doesn't make the playback quite loud enough.</p>
  
  <p>The behaviour seems to vary across devices &mdash; Sony Ericssons are particularly low, HTC devices are reasonable, and the Samsung Galaxy S is actually very loud when the volume is turned up to the maximum.</p>
  
  <p>Are there any relatively simple approaches, using the Android SDK, that could, say, double the volume while playing back from the AMR file?</p>
  
  <p>I note that <a href="http://developer.android.com/reference/android/media/AudioTrack.html" rel="noreferrer"><code>AudioTrack</code></a> allows you to manipulate audio, but this seems to be for raw PCM streams.</p>