Freeze/Melt
From Just Solve the File Format Problem
(Difference between revisions)
(Added an extension found "in the wild" (although I cannot get the decompressor to compile, and, as I do not want to set up an emulator, cannot test this). Fixed link.) |
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|subcat=Compression | |subcat=Compression | ||
|extensions={{ext|F}}, {{ext|f}}, {{ext|lzc}} | |extensions={{ext|F}}, {{ext|f}}, {{ext|lzc}} | ||
| + | |released=≤1991 | ||
}} | }} | ||
| − | '''Freeze''' is a file compression utility used from the command line in Unix-style operating systems. '''Melt''' is the corresponding decompressor. It is considered obsolete now in favor of [[gzip]]. | + | '''Freeze''' is a file compression utility used from the command line in Unix-style operating systems. '''Melt''' is the corresponding decompressor. The format is sometimes called "'''frozen'''". It was developed by Leonid A. Broukhis. It is considered obsolete now in favor of [[gzip]]. |
| + | == Format details == | ||
A two-pass compression is done with a [[Lempel-Zev]] algorithm on the first pass and a dynamic [[Huffman coding|Huffman algorithm]] on the second. The characteristics of the Huffman table used are added to the file. File attributes, ownership, etc., are preserved, and a .F extension is added. A two-byte magic number is prepended to the file (\037\236 octal for versions 1.x, and \037\237 for later versions). | A two-pass compression is done with a [[Lempel-Zev]] algorithm on the first pass and a dynamic [[Huffman coding|Huffman algorithm]] on the second. The characteristics of the Huffman table used are added to the file. File attributes, ownership, etc., are preserved, and a .F extension is added. A two-byte magic number is prepended to the file (\037\236 octal for versions 1.x, and \037\237 for later versions). | ||
Revision as of 15:46, 18 February 2019
Freeze is a file compression utility used from the command line in Unix-style operating systems. Melt is the corresponding decompressor. The format is sometimes called "frozen". It was developed by Leonid A. Broukhis. It is considered obsolete now in favor of gzip.
Format details
A two-pass compression is done with a Lempel-Zev algorithm on the first pass and a dynamic Huffman algorithm on the second. The characteristics of the Huffman table used are added to the file. File attributes, ownership, etc., are preserved, and a .F extension is added. A two-byte magic number is prepended to the file (\037\236 octal for versions 1.x, and \037\237 for later versions).
References
- Man page (in NOAA site, which should know something about freezing!)
- Source code
