getid3_mp3::MPEGaudioFrameLength( int|string $bitrate, string $version, string $layer, bool $padding, int $samplerate ): int|false

1970	public static function MPEGaudioFrameLength(&$bitrate, &$version, &$layer, $padding, &$samplerate) {1971		static $AudioFrameLengthCache = array();1972 1973		if (!isset($AudioFrameLengthCache[$bitrate][$version][$layer][$padding][$samplerate])) {1974			$AudioFrameLengthCache[$bitrate][$version][$layer][$padding][$samplerate] = false;1975			if ($bitrate != 'free') {1976 1977				if ($version == '1') {1978 1979					if ($layer == '1') {1980 1981						// For Layer I slot is 32 bits long1982						$FrameLengthCoefficient = 48;1983						$SlotLength = 4;1984 1985					} else { // Layer 2 / 31986 1987						// for Layer 2 and Layer 3 slot is 8 bits long.1988						$FrameLengthCoefficient = 144;1989						$SlotLength = 1;1990 1991					}1992 1993				} else { // MPEG-2 / MPEG-2.51994 1995					if ($layer == '1') {1996 1997						// For Layer I slot is 32 bits long1998						$FrameLengthCoefficient = 24;1999						$SlotLength = 4;2000 2001					} elseif ($layer == '2') {2002 2003						// for Layer 2 and Layer 3 slot is 8 bits long.2004						$FrameLengthCoefficient = 144;2005						$SlotLength = 1;2006 2007					} else { // layer 32008 2009						// for Layer 2 and Layer 3 slot is 8 bits long.2010						$FrameLengthCoefficient = 72;2011						$SlotLength = 1;2012 2013					}2014 2015				}2016 2017				// FrameLengthInBytes = ((Coefficient * BitRate) / SampleRate) + Padding2018				if ($samplerate > 0) {2019					$NewFramelength  = ($FrameLengthCoefficient * $bitrate) / $samplerate;2020					$NewFramelength  = floor($NewFramelength / $SlotLength) * $SlotLength; // round to next-lower multiple of SlotLength (1 byte for Layer 2/3, 4 bytes for Layer I)2021					if ($padding) {2022						$NewFramelength += $SlotLength;2023					}2024					$AudioFrameLengthCache[$bitrate][$version][$layer][$padding][$samplerate] = (int) $NewFramelength;2025				}2026			}2027		}2028		return $AudioFrameLengthCache[$bitrate][$version][$layer][$padding][$samplerate];2029	}