GENMIDI.OP2 OPL2 sound bank: PHP parsing library

GENMIDI.OP2 is a sound bank file used by players based on DMX sound library to play MIDI files with General MIDI instruments using OPL2 sound chip (which was commonly installed on popular AdLib and Sound Blaster sound cards).

Major users of DMX sound library include:

  • Original Doom game engine (and games based on it: Heretic, Hexen, Strife, Chex Quest)
  • Raptor: Call of the Shadows

File extension

op2

KS implementation details

License: CC0-1.0

This page hosts a formal specification of GENMIDI.OP2 OPL2 sound bank using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

PHP source code to parse GENMIDI.OP2 OPL2 sound bank

GenmidiOp2.php

<?php
// This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild

/**
 * GENMIDI.OP2 is a sound bank file used by players based on DMX sound
 * library to play MIDI files with General MIDI instruments using OPL2
 * sound chip (which was commonly installed on popular AdLib and Sound
 * Blaster sound cards).
 * 
 * Major users of DMX sound library include:
 * 
 * * Original Doom game engine (and games based on it: Heretic, Hexen, Strife, Chex Quest)
 * * Raptor: Call of the Shadows 
 */

class GenmidiOp2 extends \Kaitai\Struct\Struct {
    public function __construct(\Kaitai\Struct\Stream $_io, \Kaitai\Struct\Struct $_parent = null, \GenmidiOp2 $_root = null) {
        parent::__construct($_io, $_parent, $_root);
        $this->_read();
    }

    private function _read() {
        $this->_m_magic = $this->_io->ensureFixedContents("\x23\x4F\x50\x4C\x5F\x49\x49\x23");
        $this->_m_instruments = [];
        $n = 175;
        for ($i = 0; $i < $n; $i++) {
            $this->_m_instruments[] = new \GenmidiOp2\InstrumentEntry($this->_io, $this, $this->_root);
        }
        $this->_m_instrumentNames = [];
        $n = 175;
        for ($i = 0; $i < $n; $i++) {
            $this->_m_instrumentNames[] = \Kaitai\Struct\Stream::bytesToStr(\Kaitai\Struct\Stream::bytesTerminate(\Kaitai\Struct\Stream::bytesStripRight($this->_io->readBytes(32), 0), 0, false), "ASCII");
        }
    }
    protected $_m_magic;
    protected $_m_instruments;
    protected $_m_instrumentNames;
    public function magic() { return $this->_m_magic; }
    public function instruments() { return $this->_m_instruments; }
    public function instrumentNames() { return $this->_m_instrumentNames; }
}

namespace \GenmidiOp2;

class InstrumentEntry extends \Kaitai\Struct\Struct {
    public function __construct(\Kaitai\Struct\Stream $_io, \GenmidiOp2 $_parent = null, \GenmidiOp2 $_root = null) {
        parent::__construct($_io, $_parent, $_root);
        $this->_read();
    }

    private function _read() {
        $this->_m_flags = $this->_io->readU2le();
        $this->_m_finetune = $this->_io->readU1();
        $this->_m_note = $this->_io->readU1();
        $this->_m_instruments = [];
        $n = 2;
        for ($i = 0; $i < $n; $i++) {
            $this->_m_instruments[] = new \GenmidiOp2\Instrument($this->_io, $this, $this->_root);
        }
    }
    protected $_m_flags;
    protected $_m_finetune;
    protected $_m_note;
    protected $_m_instruments;
    public function flags() { return $this->_m_flags; }
    public function finetune() { return $this->_m_finetune; }

    /**
     * MIDI note for fixed instruments, 0 otherwise
     */
    public function note() { return $this->_m_note; }
    public function instruments() { return $this->_m_instruments; }
}

namespace \GenmidiOp2;

class Instrument extends \Kaitai\Struct\Struct {
    public function __construct(\Kaitai\Struct\Stream $_io, \GenmidiOp2\InstrumentEntry $_parent = null, \GenmidiOp2 $_root = null) {
        parent::__construct($_io, $_parent, $_root);
        $this->_read();
    }

    private function _read() {
        $this->_m_op1 = new \GenmidiOp2\OpSettings($this->_io, $this, $this->_root);
        $this->_m_feedback = $this->_io->readU1();
        $this->_m_op2 = new \GenmidiOp2\OpSettings($this->_io, $this, $this->_root);
        $this->_m_unused = $this->_io->readU1();
        $this->_m_baseNote = $this->_io->readS2le();
    }
    protected $_m_op1;
    protected $_m_feedback;
    protected $_m_op2;
    protected $_m_unused;
    protected $_m_baseNote;
    public function op1() { return $this->_m_op1; }

    /**
     * Feedback/AM-FM (both operators)
     */
    public function feedback() { return $this->_m_feedback; }
    public function op2() { return $this->_m_op2; }
    public function unused() { return $this->_m_unused; }

    /**
     * Base note offset
     */
    public function baseNote() { return $this->_m_baseNote; }
}

/**
 * OPL2 settings for one operator (carrier or modulator)
 */

namespace \GenmidiOp2;

class OpSettings extends \Kaitai\Struct\Struct {
    public function __construct(\Kaitai\Struct\Stream $_io, \GenmidiOp2\Instrument $_parent = null, \GenmidiOp2 $_root = null) {
        parent::__construct($_io, $_parent, $_root);
        $this->_read();
    }

    private function _read() {
        $this->_m_tremVibr = $this->_io->readU1();
        $this->_m_attDec = $this->_io->readU1();
        $this->_m_sustRel = $this->_io->readU1();
        $this->_m_wave = $this->_io->readU1();
        $this->_m_scale = $this->_io->readU1();
        $this->_m_level = $this->_io->readU1();
    }
    protected $_m_tremVibr;
    protected $_m_attDec;
    protected $_m_sustRel;
    protected $_m_wave;
    protected $_m_scale;
    protected $_m_level;

    /**
     * Tremolo/vibrato/sustain/KSR/multi
     */
    public function tremVibr() { return $this->_m_tremVibr; }

    /**
     * Attack rate/decay rate
     */
    public function attDec() { return $this->_m_attDec; }

    /**
     * Sustain level/release rate
     */
    public function sustRel() { return $this->_m_sustRel; }

    /**
     * Waveform select
     */
    public function wave() { return $this->_m_wave; }

    /**
     * Key scale level
     */
    public function scale() { return $this->_m_scale; }

    /**
     * Output level
     */
    public function level() { return $this->_m_level; }
}