player/js/elements/svgElements/effects/SVGGaussianBlurEffect.js

function SVGGaussianBlurEffect(filter, filterManager){
    // Outset the filter region by 100% on all sides to accommodate blur expansion.
    filter.setAttribute('x','-100%');
    filter.setAttribute('y','-100%');
    filter.setAttribute('width','300%');
    filter.setAttribute('height','300%');

    this.filterManager = filterManager;
    var feGaussianBlur = createNS('feGaussianBlur');
    filter.appendChild(feGaussianBlur);
    this.feGaussianBlur = feGaussianBlur;
}

SVGGaussianBlurEffect.prototype.renderFrame = function(forceRender){
    if(forceRender || this.filterManager._mdf){
        // Empirical value, matching AE's blur appearance.
        var kBlurrinessToSigma = 0.3;
        var sigma = this.filterManager.effectElements[0].p.v * kBlurrinessToSigma;

        // Dimensions mapping:
        //
        //   1 -> horizontal & vertical
        //   2 -> horizontal only
        //   3 -> vertical only
        //
        var dimensions = this.filterManager.effectElements[1].p.v;
        var sigmaX = (dimensions == 3) ? 0 : sigma;
        var sigmaY = (dimensions == 2) ? 0 : sigma;

        this.feGaussianBlur.setAttribute('stdDeviation', sigmaX + ' ' + sigmaY);

        // Repeat edges mapping:
        //
        //   0 -> off -> duplicate
        //   1 -> on  -> wrap
        var edgeMode = (this.filterManager.effectElements[2].p.v == 1) ? 'wrap' : 'duplicate';
        this.feGaussianBlur.setAttribute('edgeMode', edgeMode);
    }
}