AC1D File

What are AC1D files and how to open them

Are you having problems opening an AC1D file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your AC1D files.

What is an AC1D file?

An .AC1D file is an AC1D-DC1A Packer file.

AC1D-DC1A Packer is a module packer format for Amiga music files created by Carsten Sorensen (aka Slammer), from the demo group Anarchy. It was first used in 1992, including in the demo "In the Kitchen," and applied later in several Commodore Amiga games. Its purpose is to compress or "pack" tracker module files in a special form so that player routines can decompress them for playback.

Files in this format are produced by the packer tool written by Sorensen; once packed, they are distributed or stored, then unpacked by module players (software that supports the AC1D-DC1A scheme) or converters. After unpacking, the file becomes a standard tracker module containing sample data, pattern data, instruments, etc. NostalgicPlayer recognizes AC1D-DC1A-packed files, and conversion tools such as ProWizard can convert them back into normal module formats such as ModTracker format.

Each file begins with a signature marking its packed nature: at offset 2 it holds the four bytes AC 1D 00 00. That byte signature identifies the AC1D-DC1A Packer format and distinguishes it from ordinary unpacked modules.

How to open AC1D files

Important: Different programs may use files with the AC1D file extension for different purposes, so unless you are sure which format your AC1D file is, you may need to try a few different programs.

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

Last updated: August 16, 2026

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