Soundfinder Bookmarklet

soundfinder.js

// MIT License 
// by @mrflix

(function(){

  // Template Matching algorithm using correlation coeffizient
  // http://en.wikipedia.org/wiki/Template_matching
  // learned at HTW Berlin tought by Prof. Dr. Kai Uwe Barthel
  function getCorrelationCoeffizient(data1, data2){
    var sumI = 0, sumI2 = 0, sumIR = 0, sumR = 0, sumR2 = 0;
    var nR = data1.length;

    for(var i=0; i<nR; i++){
      var vI = data1[i];
      var vR = data2[i];

      sumI += vI;
      sumI2 += vI * vI;

      sumR += vR;
      sumR2 += vR * vR;

      sumIR += vI * vR;
    }

    var meanI = sumI / nR;
    var meanR = sumI / nR;
    var sigmaI = Math.sqrt(sumI2 - nR * meanI * meanI);
    var sigmaR = Math.sqrt(sumR2 - nR * meanR * meanR);
    
    return (sumIR - nR * meanI * meanR) / (sigmaI * sigmaR);
  }

  // place a yellow star onto the album cover
  function placeStar(i){
    $('.searchList__item').eq(i).find('.image').append($('<span class="star">★</span>').css({
      position: 'absolute',
      right: '-13px',
      bottom: '-18px',
      fontSize: '34px',
      color: 'hsl(48,100%,50%)',
      textShadow: '0 1px 3px rgba(0, 0, 0, 0.21)'
    }));
  }

  var waveformData = [];

  // collect all waveforms
  $('canvas.waveform__layer:first-child').each(function(i, canvas){
    var ctx = canvas.getContext('2d');
    waveformData.push( ctx.getImageData(0,0,canvas.clientWidth,canvas.clientHeight).data );
  });

  // compare each waveform against one another
  // and star them if their euqal enough (0.9 threshold)
  for(var i=0, l=waveformData.length; i<l; i++){
    for(var j=1; j < (l-i); j++){
      var coeffizient = getCorrelationCoeffizient(waveformData[i], waveformData[i+j]);
      console.log(coeffizient);
      if(coeffizient > 0.9){
        placeStar(i);
        placeStar(i+j);
      }
    }
  }
})()

soundfinder.min.js

javascript:(function()%7Bfunction e(e,t)%7Bvar n%3D0,r%3D0,i%3D0,s%3D0,o%3D0%3Bvar u%3De.length%3Bfor(var a%3D0%3Ba<u%3Ba%2B%2B)%7Bvar f%3De%5Ba%5D%3Bvar l%3Dt%5Ba%5D%3Bn%2B%3Df%3Br%2B%3Df*f%3Bs%2B%3Dl%3Bo%2B%3Dl*l%3Bi%2B%3Df*l%7Dvar c%3Dn/u%3Bvar h%3Dn/u%3Bvar p%3DMath.sqrt(r-u*c*c)%3Bvar d%3DMath.sqrt(o-u*h*h)%3Breturn(i-u*c*h)/(p*d)%7Dfunction t(e)%7B%24(".searchList__item").eq(e).find(".image").append(%24(%27<span class%3D"star">★</span>%27).css(%7Bposition:"absolute",right:"-13px",bottom:"-18px",fontSize:"34px",color:"hsl(48,100%25,50%25)",textShadow:"0 1px 3px rgba(0,0,0,0.21)"%7D))%7Dvar n%3D%5B%5D%3B%24("canvas.waveform__layer:first-child").each(function(e,t)%7Bvar r%3Dt.getContext("2d")%3Bn.push(r.getImageData(0,0,t.clientWidth,t.clientHeight).data)%7D)%3Bfor(var r%3D0,i%3Dn.length%3Br<i%3Br%2B%2B)%7Bfor(var s%3D1%3Bs<i-r%3Bs%2B%2B)%7Bvar o%3De(n%5Br%5D,n%5Br%2Bs%5D)%3Bconsole.log(o)%3Bif(o>.9)%7Bt(r)%3Bt(r%2Bs)%7D%7D%7D%7D)()