sclass SimpleBaseDrumFinder1 {

  int windowSize = 30;

  long count;

  double factor = 1.35; // how much higher max must be than avg

  int maxAscentTime = 4; // wait if it keeps ascending before triggering

  int minDownTime = 10; // don't trigger again for this long

  double minAbsoluteLoudness = 0.03;

  transient RollingAverage ra;

  transient RollingMaximum rm;

  transient double lastValue, avgAtAscendStart;

  transient long ascendingSince = 0, downSince = 0;

  transient Pair<LongRange, Double> lastBaseDrum;

  void addFrequencyImageBrightness(double b) {

    if (ra == null) ra = new RollingAverage(windowSize);

    if (rm == null) rm = new RollingMaximum(windowSize);

    ra.add(b);

    double max = rm.addAndGet(b), avg = ra!;

    ++count;

    bool ascending = b >= lastValue;

    lastValue = b;

    if (downSince != 0 && count < downSince+minDownTime) ret;

    // mark start of ascent

    if (ascending && ascendingSince == 0) {

      ascendingSince = count;

      avgAtAscendStart = avg;

    }

    if (ascendingSince != 0 && (!ascending || ascendingSince+maxAscentTime == count))

      if (lastValue >= minAbsoluteLoudness)

        trigger(ascendingSince, count-1, b/max(0.001, avgAtAscendStart));

    if (!ascending) ascendingSince = 0;

  }

  void trigger(long begin, long end, double ratio) {

    if (ratio < factor) ret;

    print("Base drum found from " + begin + " to " + end + ", ratio=" + ratio + ", last loudness: " + lastValue);

    lastBaseDrum = pair(longRange(begin, end), ratio);

    downSince = end;

  }

  Pair<LongRange, Double> getAndClearLastEvent() {

    try {

      ret lastBaseDrum;

    } finally {

      lastBaseDrum = null;

    }

  }

}