public void setVolume(float gain) {
        //@TargetApi(Build.VERSION_CODES.LOLLIPOP)
        //mAudioTrack.setVolume(gain);

        setStereoVolume(gain, gain);
    }
@see android.media.AudioTrack#setVolume(float)
MediaPlayer/src/main/java/net/protyposis/android/mediaplayer/AudioPlayback.java