IMFPlayer

A simple, modern IMF (id Music Format) player written in Swift for macOS.

This project is a clean Swift reimplementation of the classic id_sd-style IMF playback pipeline, using AVAudioEngine for audio output and the well-tested DOSBox dbopl core for OPL2 synthesis. It intentionally avoids SDL and timer-based loops in favor of a sample-accurate, pull-based audio design.

The result is accurate, stable playback of IMF music on modern macOS systems.

Credit to the original source materials for this project: http://sourceforge.net/projects/clonekeenplus/files/Tools/IMFPlayer/

The SDL2 version for macOS can still be found on the archive/sdl2 branch.

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Features

• Swift IMF parser and sequencer (Type 0 and Type 1)
• Sample-accurate timing (no polling loops or timers)
• OPL2 synthesis via DOSBox dbopl
• AVAudioEngine streaming output (Float32)
• Command-line interface
• No SDL2 or platform-specific audio hacks

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Architecture Overview

Classic DOS IMF playback (id_sd) combined sequencing, timing, and hardware access in one module.
This project preserves the behavior while modernizing the structure:

• IMFParser
  Parses IMF files into register write events and delays.

• IMFSequencer
  Advances IMF ticks deterministically in sample time.

• OPLDriver
  Swift-facing wrapper around the DOSBox dbopl core.

• AudioEngine
  Uses AVAudioEngine + AVAudioSourceNode to pull audio frames.

All sequencing happens inside the audio callback, ensuring stable timing and glitch-free playback.

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Building & Running

Requirements

• macOS
• Xcode or Swift toolchain
• Swift 5.9+

Build & Run

swift run -c release -- IMFPlayerSwift path/to/music.imf