getid3_ogg::ParseOpusPageHeader

	 *
	 * @return bool
	 */
	public function ParseOpusPageHeader(&$filedata, &$filedataoffset, &$oggpageinfo) {
		$info = &$this->getid3->info;
		$info['audio']['dataformat']   = 'opus';
		$info['mime_type']             = 'audio/ogg; codecs=opus';

		/** @todo find a usable way to detect abr (vbr that is padded to be abr) */
		$info['audio']['bitrate_mode'] = 'vbr';

		$info['audio']['lossless']     = false;

		$info['ogg']['pageheader']['opus']['opus_magic'] = substr($filedata, $filedataoffset, 8); // hard-coded to 'OpusHead'
		$filedataoffset += 8;
		$info['ogg']['pageheader']['opus']['version']    = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset,  1));
		$filedataoffset += 1;

		if ($info['ogg']['pageheader']['opus']['version'] < 1 || $info['ogg']['pageheader']['opus']['version'] > 15) {
			$this->error('Unknown opus version number (only accepting 1-15)');
			return false;
		}

		$info['ogg']['pageheader']['opus']['out_channel_count'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset,  1));
		$filedataoffset += 1;

		if ($info['ogg']['pageheader']['opus']['out_channel_count'] == 0) {
			$this->error('Invalid channel count in opus header (must not be zero)');
			return false;
		}

		$info['ogg']['pageheader']['opus']['pre_skip'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset,  2));
		$filedataoffset += 2;

		$info['ogg']['pageheader']['opus']['input_sample_rate'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset,  4));
		$filedataoffset += 4;

		//$info['ogg']['pageheader']['opus']['output_gain'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset,  2));
		//$filedataoffset += 2;

		//$info['ogg']['pageheader']['opus']['channel_mapping_family'] = getid3_lib::LittleEndian2Int(substr($filedata, $filedataoffset,  1));
		//$filedataoffset += 1;

		$info['opus']['opus_version']       = $info['ogg']['pageheader']['opus']['version'];
		$info['opus']['sample_rate_input']  = $info['ogg']['pageheader']['opus']['input_sample_rate'];
		$info['opus']['out_channel_count']  = $info['ogg']['pageheader']['opus']['out_channel_count'];

		$info['audio']['channels']          = $info['opus']['out_channel_count'];
		$info['audio']['sample_rate_input'] = $info['opus']['sample_rate_input'];