public function build()
{
$writer = new Media_SWF_Parser();
$writer->putSWFHeader($this->_headers);
/* SWF Tags */
foreach ($this->_tags as $tag) {
$writer->putTag($tag);
}
$fileLength = $writer->getByteOffset();
$this->_headers['FileLength'] = $fileLength;
$writer->setFileLength($fileLength);
return $writer->output();
}