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From: jloup@gzip.OmitThis.org (Jean-loup Gailly)
Newsgroups: comp.compression,comp.compression.research,news.answers,comp.answers
Subject: comp.compression Frequently Asked Questions (part 1/3)
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Summary: *** READ THIS BEFORE POSTING ***
Keywords: data compression, FAQ
Xref: senator-bedfellow.mit.edu comp.compression:43351 comp.compression.research:2985 news.answers:148677 comp.answers:34619
Archive-name: compression-faq/part1
Last-modified: Jan 9th, 1999
It is insufficiently considered that
men more often require to be reminded
than informed.
Samuel Johnson
This file is part 1 of a set of Frequently Asked Questions (FAQ) for
the groups comp.compression and comp.compression.research. If you
can't find part 2 or 3, see item 53 below. A copy of this FAQ is available
by ftp in ftp://rtfm.mit.edu/pub/usenet/news.answers/compression-faq/
files part1 to part3. This FAQ is also accessible in the World Wide Web at
http://www.faqs.org/faqs/compression-faq/part1/preamble.html or
http://www.cis.ohio-state.edu/hypertext/faq/usenet/compression-faq/top.html
Certain questions get asked time and again, and this is an attempt to
reduce the bandwidth taken up by these posts and their associated
replies. If you have a question, *please* check this file before you
post. It may save a lot of peoples time.
If you have not already read the overall Usenet introductory material
posted to "news.announce.newusers", please do. It is also available by
ftp in ftp://garbo.uwasa.fi/pc/doc-net/usenews.zip (see item 2 below
about .zip).
If you don't want to see this FAQ regularly, please add the subject
line to your kill file. If you don't know what a kill file is, get by
ftp the file ftp://rtfm.mit.edu/pub/usenet/news.answers/killfile-faq
If you have corrections or suggestions for this FAQ, send them to
Jean-loup Gailly <jloup at gzip.org>. (Replace " at " with "@". This is
a protection against junk mail. Sorry for the inconvenience.)
Part 1 is oriented towards practical usage of compression programs.
Part 2 is more intended for people who want to know how compression works.
Part 3 is a long (but somewhat obsolete) list of image compression hardware.
Main changes relative to the previous version:
- fixed url for Mark Nelson's home page [items 9.2 and 78]
- new version of MPEG library [item 15]
Contents
========
General questions:
[1] What are these newsgroups about?
[2] What is this .xxx file type?
Where can I find the corresponding compression program?
[3] What is the latest pkzip version?
[4] What is an archiver?
[5] What is the best general purpose compression program?
[7] Which books should I read?
[8] What about patents on data compression algorithms?
[9] Compression of random data (WEB, Gilbert and others)
[10] Fake compression programs (OWS, WIC)
[11] What is the V.42bis standard?
[12] I need source for the winners of the Dr Dobbs compression contest
[13] I need source for arithmetic coding
Image and audio compression:
[15] Where can I get image compression programs?
[16] What is the state of the art in lossless image compression?
[17] What is the state of fractal compression?
[18] I need specs and source for TIFF and CCITT group 4 Fax.
[19] What is JPEG?
[20] I am looking for source of an H.261/H.263 codec and MPEG
[25] Fast DCT (Discrete Cosine Transform) algorithms
[26] Are there algorithms and standards for audio compression?
Common problems:
[30] My archive is corrupted!
[31] pkunzip reports a CRC error!
[32] VMS zip is not compatible with pkzip!
[33] I have a problem with Stacker or DoubleSpace!
Questions which do not really belong to comp.compression:
[50] What is this 'tar' compression program?
[51] I need a CRC algorithm
[52] What about those people who continue to ask frequently asked questions?
[53] Where are FAQ lists archived?
[54] I need specs for graphics formats
[55] Where can I find Lenna and other images?
[56] I am looking for a message digest algorithm
[57] I have lost my password on a .zip file
Part 2: (Long) introductions to data compression techniques
[70] Introduction to data compression (long)
Huffman and Related Compression Techniques
Arithmetic Coding
Substitutional Compressors
The LZ78 family of compressors
The LZ77 family of compressors
[71] Introduction to MPEG (long)
What is MPEG?
Does it have anything to do with JPEG?
Then what's JBIG and MHEG?
What has MPEG accomplished?
So how does MPEG I work?
What about the audio compression?
So how much does it compress?
What's phase II?
When will all this be finished?
How do I join MPEG?
How do I get the documents, like the MPEG I draft?
[72] What is wavelet theory?
[73] What is the theoretical compression limit?
[74] Introduction to JBIG
[75] Introduction to JPEG
[76] What is Vector Quantization?
[77] Introduction to Fractal compression
[78] The Burrows-Wheeler block sorting algorithm
Part 3: (Long) list of image compression hardware
[85] Image compression hardware
[99] Acknowledgments
Search for "Subject: [#]" to get to question number # quickly. Some news
readers can also take advantage of the message digest format used here.
If you know very little about data compression, read question 70 in
part 2 first.
------------------------------------------------------------------------------
Subject: [1] What are these newsgroups about?
comp.compression is the place to discuss about data compression, both
lossless (for text or data) and lossy (for images, sound, etc..).
comp.compression.research was created later to provide a forum for
current research on data compression and data compression algorithms;
this group is now moderated. If you are not experienced in data compression,
please post in comp.compression only.
An archive of this newsgroup since Oct 1993 is available in
ftp://spib.rice.edu/spib/news/comp.compression/
Excellent collections of compression based information are provided at
http://www.internz.com/compression-pointers.html and
http://www.sr3.t.u-tokyo.ac.jp/~arimura/compression_links.html
If you only want to find a particular compression program for a
particular operating system, please read first this FAQ and the
article "How to find sources" which is regularly posted in
news.answers.
If you can't resist posting such a request, other groups are probably
more appropriate (comp.binaries.ibm.pc.wanted, comp.os.msdos.apps,
comp.sources.wanted, comp.sys.mac.wanted, comp.archives.msdos.d, comp.dsp,
alt.graphics.pixutils). Please post your request in comp.compression
only as a last resource.
If your question is about graphics only (no compression), please
post to comp.graphics.misc, *after* reading the comp.graphics FAQ (see
item 54 below). For some unknown reason, many questions about
graphics are incorrectly posted to comp.compression.
For questions related to audio compression, check also comp.dsp.
Please do not post any program in binary form to comp.compression.
Very short sources can be
