ARJ
ARJ, which stands for Archived by Robert Jung, is a lossless compression format designed by Robert K. Jung in 1991 and sold through ARJ Software. The format used proprietary compression algorithms called AR001 and AR002, though the patent has now expired.
Archive software for compressing and decompressing ARJ files was initially written for MS-DOS, but later ported to Windows. Over the years, many features were added to the format like support for multi-volume compression, self-extraction, and weak encryption. The format's primary competitor of the time was ZIP, but ZIP became popular earlier and had similar features and compression ratios, so ARJ never supplanted ZIP's dominance. However, ARJ did have some proponents, and, before both formats were vastly eclipsed by 7Z, ARJ saw limited success. You can still find the occasional ARJ archive among a mountain of ZIPs if you look through old file catalogs from the 1990s.
Despite never really taking off, ARJ Software continued to upgrade their programs, adding a Windows port, and maintaining the MS-DOS port all the way to 2012. Hobbyists have since created free cross-platform open source versions of the software.
Contents
Personal
Like most people, I predominately used ZIP throughout the 1990s. I occasionally saw ARJ files, but, because they were so rare, and I didn't know how to open them, I just ignored those files compressed with the format. It wasn't until I became interested in compression formats that I decided to take a look at the ARJ format. The very first time I used the ARJ Archiver program was to create a benchmark test for this page, and I found it to be very similar to PKZip.
While I appreciate that ARJ was comparable to ZIP, the fact that 7Z now exists makes the format a historical quirk rather than a viable compression option.
One thing I noticed while writing this page was the ARJ Software website proselytizes religious values, which is a bit odd for a company. In fact, the web site claims the god Robert K. Jung believes in is the actual senior partner of the company. I'll bet the employees get awfully nervous when there's a boardroom meeting!
Software
| Program | Platforms | License | Functions | Notes |
|---|---|---|---|---|
| 7-Zip | Linux, Windows | Free, Open | Decompress | Very configurable and easy to use. Supports dozens of other formats as well. |
| ARJ Archiver | MS-DOS, Windows | Crippleware | Compress, Edit, Decompress | Command-line only. Lots of options, but no longer updated. |
| PeaZip | BSD, Linux, Windows | Free, Open | Decompress | Very configurable, but poor UI. |
| WinRAR | Windows | Crippleware | Decompress | Crippleware; not recommended. |
Bechmarks
To see how well ARJ compression compares to other archive formats, I ran some comparison tests by compressing the entire contents of the Windows 3 Multimedia Edition CD-ROM. The ARJ Archiver compressed to nearly the same size as PK Zip compressed to ZIP, but 7-Zip compressed better than both, especially when using the superior 7Z format.
| Archiver | Version | Format | File Size | Compression Ratio | Percent of Original Size |
|---|---|---|---|---|---|
| Uncompressed | - | - | 330,078,040 bytes (314 MB) | 1.0:1 | 100% |
| PKZip | v2.04g (16-bit) | ZIP | 147,959,464 bytes (141 MB) | 2.2:1 | 45% |
| ARJ Archiver | v3.20 (32-bit) | ARJ | 147,603,578 bytes (140 MB) | 2.2:1 | 45% |
| 7-Zip | v19.0 (64-bit) | ZIP | 139,644,891 bytes (133 MB) | 2.4:1 | 42% |
| 7-Zip | v19.0 (64-bit) | 7Z | 100,826,752 bytes (96 MB) | 3.3:1 | 31% |
Links
- arj.sourceforge.net - Open source cross-platform port.
