chromaprint-fixed/lib/silenceRemover.js

A JavaScript implementation of AcoustID Chromaprint

// Generated by CoffeeScript 2.2.3
(function() {
  var silenceRemover;

  if (this.chromaprint == null) {
    this.chromaprint = {};
  }

  
  // Gets a function for removing silence from a buffer. It can be configured with
  // a silence threshold. The window is also configurable (see the filter function
  // below), but defaults to 55, which, I am told, is 5ms at 11025 Hz.
  silenceRemover = function(threshold, window = 55) {
    var filter;
    // The filter returns a function that returns true if the average ever passes
    // above the threshold. The window is the starting point when summing up the
    // bytes for the average.
    filter = function(window) {
      var finished;
      finished = false;
      return function(byte, index) {
        return finished || (finished = ((window += byte) / (index + 1)) > threshold);
      };
    };
    // This function returns what it's given only if the average has s
    // The returned function takes an array of bytes, only returns those that occur
    // after the average has surpassed the silence threshold.
    return function(input) {
      return input.filter(filter(window));
    };
  };

  this.chromaprint.silenceRemover = silenceRemover;

}).call(this);