PhotoCD-DT: Kodak Photo CD DataType for Amiga

photocd.datatype adds Kodak Photo CD (.PCD) support to the Amiga DataTypes system.

Features

• DataTypes-based .PCD support for Amiga systems with picture.datatype V44+
• Direct RGB decode path inside photocd.datatype
• 64Base (6144x4096) support when the original Photo CD companion files are present
• Optional Amiga-side helper tools: PhotoCD Prefs and dtprobe
• Reproducible host-generated PhotoCD DataTypes descriptor

Requirements

Runtime

• AmigaOS 3.2 (or another system with picture.datatype V44+)
• PhotoCD Prefs uses GadTools/Intuition

Build

• Bebbo's m68k-amigaos-gcc toolchain
• a host C compiler
• lha and icontool for make lha

Quick Start

Build the main Amiga binaries and generated metadata:

make

This produces:

• build/amiga/Classes/DataTypes/photocd.datatype
• build/amiga/Prefs/PhotoCD
• build/amiga/Install
• build/amiga/PhotoCD-DT.readme
• build/amiga/Env/DataTypes/photocd.prefs

Build the optional tool and descriptor as needed:

make descriptor dtprobe

Build the distributable archive when you want the packaged release tree and .lha output:

make lha

The shared version source of truth is version.mk. The build uses that version when generating metadata and Amiga binaries.

Common Targets

• make: build metadata, runtime assets, photocd.datatype, and PhotoCD
• make metadata: regenerate build/amiga/Install and build/amiga/PhotoCD-DT.readme
• make runtime-assets: copy packaged runtime assets such as photocd.prefs
• make dtprobe: build the Amiga-side DataTypes diagnostic tool at build/amiga/C/dtprobe
• make descriptor: regenerate build/amiga/Devs/DataTypes/PhotoCD with the host-side generator
• make lha: assemble PhotoCD-DT-v<version>/ and PhotoCD-DT-v<version>.lha
• make clean: remove build products and generated package output

64Base Notes

64Base (6144x4096) images are supported, but they still require the original Photo CD companion files in the matching IPE/.../64BASE directory layout. The .PCD file alone does not contain the full 64Base image data.

Setup

On AmigaOS 3.2 and newer, it is recommended that you add a photocd filetype as a sub type under picture in your Default Icons Preferences.

Then, make sure to set it to match #?.pcd under Advanced Settings. This way you will be able to click on PCD files that lack a .info file and they will still nicely open with MultiView.

Tools

PhotoCD Prefs

The PhotoCD Prefs tool allows you to select the default decoding resolution and shows you the version of the installed photocd.datatype

dtprobe

Build the optional DataTypes probe with:

make dtprobe

This produces build/amiga/C/dtprobe, a small Amiga-side utility that:

• prints the first bytes at offsets 0 and 2048
• shows the descriptor selected by ObtainDataTypeA()
• tries NewDTObject() both generically and as a picture object

Example:

C/dtprobe RAM:IMG0001.PCD

Sample Extraction

The repository includes a helper to reconstruct an ISO from a raw BIN/CUE image and extract representative .PCD files for manual testing:

python3 tools/extract_photo_cd_samples.py --cue PCD1410.cue --out-dir /tmp/pcd-fixtures

Descriptor Generator

The repository includes a host-side generator for the PhotoCD DataTypes descriptor:

make descriptor

This builds build/host/make_pcd_descriptor and rewrites build/amiga/Devs/DataTypes/PhotoCD reproducibly.

The generated descriptor is intentionally pattern-based. Standard Kodak Photo CD files expose PCD_IPI at offset 2048, so a static first-64-bytes mask is not enough to identify them reliably. If you later add a comparison hook, the tool can also attach a raw DTCD chunk:

build/host/make_pcd_descriptor --dtcd path/to/hook -o build/amiga/Devs/DataTypes/PhotoCD

Repository Layout

• src/: datatype, prefs tool, diagnostic tool, and decoder sources
• src/decoder/: shared Photo CD decoder sources
• tools/: fixture extraction and descriptor generator
• assets/: package icons and bundled runtime assets
• build/amiga/: default Amiga output tree
• build/amiga/Devs/DataTypes/PhotoCD: generated DataTypes descriptor

The decoder source is intentionally split into smaller internal translation units:

• photocd.c
• photocd_core.c
• photocd_data.c
• photocd_huffman.c
• photocd_convert.c

This keeps the lookup tables, bitstream decoder, conversion code, and control flow separated without changing the public decoder API.

Credits

Inspired by PCD-DT35 datatype by Achim Stegemann
Decoder core basis: Sandy McGuffog and contributors
Original Photo CD format reverse engineering foundation: Hadmut Danisch

License

This project is licensed under GPL-2.0-or-later. See LICENSE.md.