DrawTextFilter.java

        filterParam.append("drawtext=fontfile='");
        filterParam.append(overlay.getFont());
        filterParam.append("':text='");
        filterParam.append(overlay.getText());
        filterParam.append("':x=(W/2)-(w)/2:y=5:draw='gt(t,");
        filterParam.append(overlay.getStartTime());
        filterParam.append(")*lt(t,");
        filterParam.append(overlay.getEndTime());
        filterParam.append(")':fontsize=");
        filterParam.append(overlay.getTextSize());
        filterParam.append(":fontcolor=");
        filterParam.append(overlay.getColour());