IFF file format experiments
The "IFF file format experiments" is a personal hobby project in which I implement several well-defined, portable and high-quality packages, which make it possible to parse, write, view and check files using the Electronic Arts' Interchange File Format (IFF) and several application formats, such as the Interleaved BitMap (ILBM) for storing pictures and 8SVX to store 8-bit audio samples, on modern platforms. The IFF container format was ubiquitous on AmigaOS, but poorly supported in most common viewers on modern platforms used nowadays.
The goal of this project is to enable third party applications to easily support IFF applications formats, similar to libraries, such as libpng for supporting PNG images and libvorbis supporting Vorbis audio files.
Motivation
The reason why I have developed these packages are the following:- Support for most IFF application formats is not present in many common viewers and players.
- Most applications have their own implementation of a specific IFF application format. Some implementations are good, others lack certain features. For example, I have seen several viewers not supporting the special Amiga screen modes, such as Extra HalfBrite (EHB) and Hold-and-Modify (HAM) or the color range cycle chunks.
- Applications can open simple IFF files that consist of a single FORM, but do not know how to deal with IFF scrap files, i.e. CATs/LISTs containing multiple FORMs of various types, possibly with shared options.
- Most applications can view IFF application formats, but cannot write them or check for their validity, which may result in crashes if invalid IFF files are opened.
- A number of open file formats have generic parser libraries, e.g. PNG (libpng), JPEG (libjpeg), GIF (giflib), Ogg (libogg), Vorbis (libvorbis) etc. that applications use to open, parse and save files. There is no equivalent for ILBM and other IFF application formats.
- For me it is fun to do it :-)
Packages
So far, the experiments have resulted in the development of the following packages:General IFF format
- libiff implements the IFF specification and provides a generic interface capable of parsing data chunks and group chunks, writing IFF files and conformance checking. Furthermore, it contains command-line utilities to inspect the contents of IFF files as well as a command-line utilities which can join several IFF files into a IFF scrap file.
Application formats
- libilbm extends libiff enabling support for Interleaved BitMap (ILBM) application chunks used to store images and provides an interface that can conveniently retrieve relevant ILBM properties. It also implements the byte run compression method and provides command-line utilities to inspect ILBM files and to compress or decompress ILBM files.
- lib8svx extends libiff enabling support for 8-bit audio sample (8SVX) application chunks and provides an interface that can conveniently retrieve relevant 8SVX properties. It also implements the fibonacci-delta compression method and provides command-line utilities to inspect 8SVX files and to compress or decompress 8SVX files.
Utilities
- libamivideo can be used to convert AmigaOS bitplanes to chunky or RGB format and vice versa. It can also emulate special Amiga screen modes, such as Extra-Halfbrite (EHB) and Hold-and-Modify (HAM).
- nix-amigaosenv is an utility function for the Nix package manager to build software for AmigaOS using a preconfigured disk image with Geek Gadgets and UAE, the Amiga emulator.
Viewers and players
- SDL_ILBM a library and command-line utility displaying ILBM images using SDL, a cross-platform library used by many games and multimedia applications. The viewer is capable of supporting various advanced features, such as animating Deluxe Paint's and Graphicraft's color cycle ranges and handling IFF scrap files.
- amiilbm is a native command-line utility for AmigaOS using my own IFF libraries to display ILBM images instead of the native AmigaOS one. It also knows how to handle IFF scrap files and it is also capable of opening images created by the PC version of Deluxe Paint.
- SDL_8SVX is a library and command-line utility capable of playing samples defined in 8SVX instruments using SDL.
Screenshots
Below I have included a number of screenshots of the SDL-based image viewer as well as the native AmigaOS viewer:SDL ILBM viewer
AmigaOS ILBM viewer
Obtaining the source code
There are no releases, as I have not defined a roadmap yet. Although the packages are usable and relatively simple to install: do not consider these libraries stable yet. The source code can be obtained from various GitHub pages, which also contains instructions how to install and use them:
- libiff GitHub page
- libilbm GitHub page
- libamivideo GitHub page
- SDL_ILBM GitHub page
- amiilbm GitHub page
- lib8svx GitHub page
- SDL_8SVX GitHub page
- Nix AmigaOS environment GitHub page
Licenses
All packages are available as free and open-source software under various non-copylefted licenses, such as the MIT license and the zlib license.
More information
- The following blog post titled: "IFF file format experiments" explains more about the history and provides more details.
- The blog post titled: "Porting software to AmigaOS (unconventional style)" covers the AmigaOS Nix build function, which can be used to backport and compile software packages for AmigaOS.
