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7-zip Compression Settings Guide
Digital Studio 7
This guide is created to help 7-zip users understand what settings do what and how to achieve
best compression on their systems, for this guide I am using 7-zip gui however I believe reading
this guide will help you with commend line version as well.
For this guide I am using 7-zip version 9.32
1) Archive Format: From this option you can select what archive format you want to use,
however because this guide is dedicated to 7z lets stick to it. although I recommend you take a
look at this article Best File Compression Method article.
2) Compression Level: This are presets for the settings, the names are pretty self explanatory,
the presets start from Store (This preset compression settings can not be edited because it does
not compress files) to Ultra (ultra is the highest compression preset, but we can achieve better
compression by manually editing settings)
Take a look at this table to understand better (source)
No compression is used, files are just stored in archive in its original size.
Recommended level of compression.
Better compression, but it is slower and needs more memory.
Best compression, but it is even slower and needs even more memory.
3) Compression Method: Here You can select the compression method, I recommend using
lzma2 because it is considered generally as the best compression method, It is always good idea
to default to it.
Take a look at this for more information (source)
Default compression method of 7z format. It provides high compression ratio
and very fast decompression.
LZMA-based compression method. It provides better multithreading support
than LZMA. But compression ratio can be worse in some cases. For best
compression ratio with LZMA2 use 1 or 2 CPU threads. If you use LZMA2
with more than 2 threads, 7-zip splits data to chunks and compresses these
chunks independently (2 threads per each chunk).
Dmitry Shkarin's PPMdH algorithm with small changes. Usually it provides
high compression ratio and high speed for text files.
Standard compression method based on BWT algorithm. Usually it provides
high speed and pretty good compression ratio for text files.
Standard compression method of ZIP and GZip formats. Compression ratio is
not too high. But it provides pretty fast compressing and decompressing.
Deflate method supports only 32 KB dictionary.
Modified version of Deflate algorithm with bigger dictionary (64KB).
More information about compression cooperation see the below table (source)
Compressed file size in bytes
124875819 93997047 85618192 72042179 85630688 72069084 165844264 168012430
119040249 87741348 81480824 70264395 81492504 70282944 165844264 166987891
114931686 84816957 79575087 69015118 79586568 69029204 165844264 166987891
102328357 81837328 69557610 67879362 69583428 67875988
100128597 80197758 67276420 66868212 67294092 66852780
99740486 78963640 65841213 65362226 65859432 65372696
4) Dictionary Size: This is very important parameter bigger dictionary size equals better
compression however here are couple of things to look out for:
1) Dictionary Size value difference: I noticed there is a cutoff point, where after some amount
of dictionary size you will not get a big compression size difference; for example between
4MB and 128 MB dictionary size there might be a huge compressed file size difference but
between 128 MB and 512 there might be only Couple of MB
2) Speed: The bigger the dictionary size is the longer it will take your PC to compress files.
3) System: This is very important you should take in consideration on what pc you are
compressing files and on what system you are going to decompress files. Why? the bigger your
dictionary size is more Memory(RAM) is required to complete compression and decompression.
When you change the value of Dictionary Size make sure that you will take a look at: Memory
usage for Compressing and Memory Usage for Decompressing
Memory usage for Compressing: Make Sure that you have more Memory(RAM) than it is
tallying you that it will use. otherwise your pc will most probably hang and require reboo.
Memory Usage for Decompressing: Make sure that on a pc you are planning on decompress
this file has more Memory(RAM) than it is asking for
5) Word Size: Higher the value the better compression you are generally going to get ( however
it is really dependent on files you are trying to compress) You might get really big difference or
might get nonexistent difference. You should keep in mind that Word Size, might almost have no
effect the size of a compressed file however it will always effect the speed of the compression so
sticking to 64 is good practice
6) Solid Block Size: With this option you can enable solid compression, which can improve
compression when storing multiple similar files. However extracting or adding a single file from
an archive like this will take longer than none solid block compression. However the best
practice is manually select the size of a block, for example if you are trying to compress 5 files
and each file is 512 MB you might select block size 512MB. Block size is up to you and your
judgement or easy way out is, just stick with the preset that 7zip is offering you like 2 GB or 4
for more information you can see this
7) Number of CPU threads: Select the number of your pc threads that 7z will use, more threads
will equal to faster compression, however some people say that, selecting more then 2 threads
might hurt the compression size.
8) Split to volumes: This will just split the archive at a special size you specified, for example if
you are trying to burn 2 GB of files on a CD you can tell 7z to split the archive every 650Mb,
What it will do is create couple of parts, Singe part will not be more than you specified (in our
situation 650MB) however uncompromising the files will require all the parts.
9) Update mode: This is where you can select update method
Take a look at this for more information (source)
Add and replace files
Add all specified files to the archive.
Update and add files
Update older files in the archive and add files that are new to
Freshen existing files
Update specified files in the archive that are older than the
selected disk files.
Replace specified files only if added files are newer. Always
add those files, which are not present in the archive. Delete
from archive those files, which are not present on the disk.
10)Create SFX archive: This will Create a Self-extracting archive you might know what this
is, You might have download a file from internet that has a 7z log and when you doable click on
it, a window appears and asks you where to extract this files. If you check SFX you are going to
create a file that will just do that Self-extracting archive.
11) Compress shared files: This option compress a file when it is open in another application.
12) Enter Password: If you enter password here the archive you are going to create will be
password protected by the password you entered.
13) Reenter password: * //Guess what to do here
14)Show Password: This will make viable the password you are entering abow
15) Encryption method: Here you select the encryption method for more information you can
take a look at this guide
16)Encrypt file names: Here you can enable or disable archive encryption.
17)Parameters: The Parameters field is for specifying any options you need that are not
available via dedicated dialog controls. for more information you can take a look here
Used information: Thank you awesome people who worked on them.
This guide version 0.76
Contact information: Studio76@mail.com
Thank you for your time