Quantum compression: Difference between revisions
Bellerophon (talk | contribs) m Reverted edits by 98.204.74.45 (talk) to last revision by 80.254.146.68 (HG) |
No edit summary Tag: references removed |
||
Line 1: | Line 1: | ||
The '''Quantum compression''' format is a |
The '''Quantum compression''' format is a somewhat obscure [[data compression]] method invented by a company called ''Cinematronics'' (written by an author identified as ''David Stafford''). Rights to it were purchased at some point by [[Microsoft]], and ''Quantum'' is one of the possible compression methods in a [[Cabinet (file format)|CAB archive]]. |
||
==Quantum (.Q) archiver== |
==Quantum (.Q) archiver== |
||
For [[DOS]], PAQ.EXE is the compressor and UNPAQ.EXE is the decompressor. QWIN.EXE is the [[Microsoft Windows|Windows]] decompressor (no [[Microsoft Windows|Windows]] compressor |
For [[DOS]], PAQ.EXE is the compressor and UNPAQ.EXE is the decompressor. QWIN.EXE is the [[Microsoft Windows|Windows]] decompressor (no [[Microsoft Windows|Windows]] compressor exists). It is much faster and has more features (e.g., selective decompression) than the [[DOS]] decompressor. Each of these require at least a 386 CPU to run. |
||
The |
The latest known version is ''0.97'' (as of 15 May, 1995). |
||
==.Q archive header== |
==.Q archive header== |
||
Line 59: | Line 59: | ||
| file date (DOS format) |
| file date (DOS format) |
||
|} |
|} |
||
⚫ | |||
⚫ | |||
⚫ | |||
⚫ | |||
big-endian format. |
|||
Immediately following the list of files is the compressed data. |
Immediately following the list of files is the compressed data. |
||
⚫ | |||
⚫ | |||
⚫ | |||
⚫ | |||
==References== |
|||
{{reflist}} |
|||
* {{cite book | last = Salomon| first = David | title = Data compression: the complete reference| publisher = Springer Verlag| year = 2007 | pages = 187| isbn = 1846286026}} |
|||
{{refend}} |
|||
==External links== |
==External links== |
||
*http:// |
*http://www.speakeasy.org/~russotto/quantumcomp.html |
||
*ftp://ftp.sac.sk/pub/sac/pack/quant097.zip |
*ftp://ftp.sac.sk/pub/sac/pack/quant097.zip |
||
[[Category:Data compression software]] |
[[Category:Data compression software]] |
Revision as of 18:49, 30 December 2010
The Quantum compression format is a somewhat obscure data compression method invented by a company called Cinematronics (written by an author identified as David Stafford). Rights to it were purchased at some point by Microsoft, and Quantum is one of the possible compression methods in a CAB archive.
Quantum (.Q) archiver
For DOS, PAQ.EXE is the compressor and UNPAQ.EXE is the decompressor. QWIN.EXE is the Windows decompressor (no Windows compressor exists). It is much faster and has more features (e.g., selective decompression) than the DOS decompressor. Each of these require at least a 386 CPU to run.
The latest known version is 0.97 (as of 15 May, 1995).
.Q archive header
Bytes | Description |
---|---|
2 | signature, must be 0x44 followed by 0x53 |
1 | major version number |
1 | minor version number |
2 | number of files which reside in this archive |
1 | table size required for decompression |
1 | compression flags |
This is immediately followed by the list of files:
Bytes | Description |
---|---|
var. | length of file name, see (*) below |
var. | file name, variable length string, not zero-terminated |
var. | length of comment field, see (*) below |
var. | comment field, variable length string, not zero-terminated |
4 | fully expanded file size in bytes |
2 | file time (DOS format) |
2 | file date (DOS format) |
(*) Strings are prefixed with their length. This takes one or two bytes. If the length is less than 128 then it is stored directly in one byte. If it is greater than 127 then the high bit of the first byte is set to 1 and the remaining fifteen bits contain the actual length in big-endian format.
Immediately following the list of files is the compressed data.