Freeze/Melt
From Just Solve the File Format Problem
(Difference between revisions)
Dan Tobias (Talk | contribs) (Created page with "{{FormatInfo |formattype=electronic |subcat=Compression |extensions={{ext|F}} }} '''Freeze''' is a file compression utility used from the command line in Unix-style operating...") |
Dan Tobias (Talk | contribs) |
||
| Line 7: | Line 7: | ||
'''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. It is considered obsolete now in favor of [[gzip]]. | ||
| − | A two-pass compression is done with a [[ | + | A two-pass compression is done with a [[Lempel-Zev]] algorithm on the first pass and a dynamic [[Huffman encoding|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 == | == References == | ||
* [http://www.esrl.noaa.gov/gmd/dv/hats/cats/stations/qnxman/freeze.html Man page] (in NOAA site, which should know something about freezing!) | * [http://www.esrl.noaa.gov/gmd/dv/hats/cats/stations/qnxman/freeze.html Man page] (in NOAA site, which should know something about freezing!) | ||
* [http://reality.sgiweb.org/freeware/source/freeze-2.3.1/ Source code] | * [http://reality.sgiweb.org/freeware/source/freeze-2.3.1/ Source code] | ||
Revision as of 16:18, 28 December 2012
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.
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
