<?php/** * Reads the music files of the 1996 version (data/musics/Sapiens1.mux, Sapiens2.mux: Harmony Assistant * songs, Myriad). Used only by the offline tool tools/render-music.php. * * Format (found by reading the files, no documentation is published): * - "EXPO" + 13 bytes, then LZW: codes MSB first, 9 to 12 bits (the width grows one code early), * no clear code, the dictionary restarts when it holds 4095 entries; * - staves: Pascal name ("Portée n"), 0x1b bytes, u16 note count, notes of 28 bytes: * 0 pitch (MIDI, 0xff = rest), 7..10 u32 duration (quarter = 40320), 14 velocity; * - digital instruments ("DGIT"): u32 size, u16 type, u16 bits, Fixed rate, u16 base note, * u16 volume, u32 loop start, loop end, length (in 16-bit samples at `rate`); * type 3 = one signed byte per 2 samples, value = ±table[|byte|] (table: 128 u16 just before the data); * type 0x4000 = raw PCM (8-bit unsigned or 16-bit big endian). */final class Mux{ public const QUARTER = 40320; public string $data; public function __construct(string $file) { $this->data = self::unexpo(file_get_contents($file)); } public static function unexpo(string $b): string { if (substr($b, 0, 4) !== 'EXPO') { throw new RuntimeException('not an EXPO file'); } $pos = 17 * 8; $nbits = strlen($b) * 8; $dict = []; $reset = function () use (&$dict): void { $dict = []; for ($i = 0; $i < 256; $i++) { $dict[] = chr($i); } }; $reset(); $width = 9; $prev = null; $out = []; while ($pos + $width <= $nbits) { $code = 0; for ($i = 0; $i < $width; $i++, $pos++) { $code = ($code << 1) | ((ord($b[$pos >> 3]) >> (7 - ($pos & 7))) & 1); } $n = count($dict); if ($code < $n) { $e = $dict[$code]; } elseif ($code === $n && $prev !== null) { $e = $prev . $prev[0]; } else { throw new RuntimeException("bad LZW code $code"); } $out[] = $e; if ($prev !== null) { $dict[] = $prev . $e[0]; } $prev = $e; if (count($dict) + 1 >= (1 << $width) && $width < 12) { $width++; } if (count($dict) >= 4095) { $reset(); $width = 9; $prev = null; } } return implode('', $out); } /** @return int beats per minute of the song header */ public function tempo(): int { // header: ... u32 bar length (0x27600), u16 tempo, u16 beats, u16 beat unit $p = strpos($this->data, "\x00\x02\x76\x00", 0x80); return unpack('n', $this->data, $p + 4)[1]; } /** @return array<int, array{name:string, notes:array<int, array{0:float,1:float,2:int,3:int}>}> notes: start, length (quarters), pitch, velocity */ public function staves(): array { $d = $this->data; $staves = []; $i = 0; while (($i = strpos($d, "Port\x8ee ", $i + 1)) !== false) { $h = $i + ord($d[$i - 1]); $count = unpack('n', $d, $h + 0x1b)[1]; $base = $h + 0x1d; if ($count === 0 || $base + 28 * $count > strlen($d)) { continue; } $t = 0; $notes = []; for ($k = 0; $k < $count; $k++) { $r = $base + 28 * $k; $len = unpack('N', $d, $r + 7)[1]; if ($len > 64 * self::QUARTER) { // not a staff of notes (the drum loops have other records) continue 2; } $pitch = ord($d[$r]); if ($pitch < 128) { $notes[] = [$t / self::QUARTER, $len / self::QUARTER, $pitch, ord($d[$r + 14])]; } $t += $len; } $staves[] = ['name' => substr($d, $i, ord($d[$i - 1])), 'notes' => $notes]; } return $staves; } /** * @return array<string, array{rate:float, base:int, volume:int, loopStart:int, loopEnd:int, samples:float[]}> * name => instrument, samples in -1..1 at `rate` */ public function instruments(): array { $d = $this->data; $list = []; $i = 0; while (($i = strpos($d, 'DGIT', $i + 1)) !== false) { // name: the Pascal string after the 0x0001 that starts the instrument chunk $name = $this->instrumentName($i); $k = $i + 4; while (!in_array(substr($d, $k + 4, 4), ["\x00\x03\x00\x10", "\x40\x00\x00\x08", "\x40\x00\x00\x10"], true)) { $k++; } ['type' => $type, 'bits' => $bits, 'rate' => $rate, 'base' => $base, 'volume' => $volume, 'ls' => $ls, 'le' => $le, 'len' => $len] = unpack('Nsize/ntype/nbits/Nrate/nbase/nvolume/Nls/Nle/Nlen', $d, $k); $rate /= 65536; $samples = []; if ($type === 3) { $t = $k + 0x2c; $table = array_values(unpack('n128', $d, $t)); $p = $t + 256; $n = intdiv($len, 2); for ($j = 0; $j < $n; $j++) { $v = ord($d[$p + $j]); $samples[] = ($v < 128 ? $table[$v] : -$table[min(127, 256 - $v)]) / 32768; } $rate /= 2; $ls = intdiv($ls, 2); $le = intdiv($le, 2); } else { $p = $k + 0x2c; if ($bits === 16) { foreach (unpack("n$len", $d, $p) as $v) { $samples[] = ($v >= 32768 ? $v - 65536 : $v) / 32768; } } else { for ($j = 0; $j < $len; $j++) { $samples[] = (ord($d[$p + $j]) - 128) / 128; } } } $list[$name] = ['rate' => $rate, 'base' => $base, 'volume' => $volume, 'loopStart' => $ls, 'loopEnd' => $le > $ls + 16 ? $le : 0, 'samples' => $samples]; } return $list; } private function instrumentName(int $dgit): string { // the chunk starts with ... 00 01 <len> <name> 00 ..., about 0x40 bytes before "MIDI" $d = $this->data; for ($p = $dgit - 0x30; $p > $dgit - 0x80; $p--) { if ($d[$p] === "\x01" && $d[$p - 1] === "\x00") { $n = ord($d[$p + 1]); $name = substr($d, $p + 2, $n); if ($n >= 3 && $n < 24 && preg_match('/^[A-Za-z0-9 \-]+$/', $name)) { return $name; } } } return 'dgit' . $dgit; }}