getid3_ac3::centerMixLevelLookup

	 *
	 * @return int|float|string|false
	 */
	public static function centerMixLevelLookup($cmixlev) {
		static $centerMixLevelLookup;
		if (empty($centerMixLevelLookup)) {
			$centerMixLevelLookup = array(
				0 => pow(2, -3.0 / 6), // 0.707 (-3.0 dB)
				1 => pow(2, -4.5 / 6), // 0.595 (-4.5 dB)
				2 => pow(2, -6.0 / 6), // 0.500 (-6.0 dB)
				3 => 'reserved'
			);