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Software tests → Compressors

Summary

• Abstract
• Objectives
• Method
• Results
• Conclusions

Abstract

We compared the 7-Zip file compressor to WinZip, WinAce and WinRAR on non-compressed files. 7-Zip was over 100% slower than any other compressor for compression, but achieved a higher compression ratio (10.6% vs 12.2% - WinRAR, first file ; 27.9% vs 31.7% - WinAce, second file), and was as fast as WinAce and WinRAR for uncompression.

Objectives

We wanted to clarify 7-Zip performances compared to WinZip, WinAce and WinRAR.
Basically, we wanted to (1) check if the 7z format is really better than the others (and see what the time cost is) and (2) check if 7-Zip really compresses better in Zip format than other Zip compressors.

Method

We used a pentium 4 1.4 GHz with 512 MB of RDRAM, running Windows 2000 SP1 on a Maxtor HD. The files to compress were on a Western Digital HD (write speed 30MB/s measured with Eraser).
Running processes when doing the tests :

Logfile of HijackThis v1.99.0

C:\WINNT\System32\smss.exe
C:\WINNT\system32\winlogon.exe
C:\WINNT\system32\services.exe
C:\WINNT\system32\lsass.exe
C:\Program Files\Sygate\SPF\smc.exe
C:\WINNT\system32\svchost.exe
C:\WINNT\system32\spoolsv.exe
C:\Program Files\Netropa\Multimedia Keyboard\nhksrv.exe
C:\WINNT\system32\DRIVERS\CDANTSRV.EXE
C:\WINNT\System32\svchost.exe
C:\WINNT\System32\nvsvc32.exe
C:\WINNT\system32\stisvc.exe
C:\WINNT\Explorer.exe
C:\Program Files\Dell\Solution Center\service.exe
C:\Program Files\Netropa\Multimedia Keyboard\MMKeybd.exe
C:\PROGRA~1\Adaptec\DirectCD\directcd.exe
C:\Program Files\Netropa\Multimedia Keyboard\mmusbkb2.exe
C:\Program Files\Netropa\Onscreen Display\OSD.exe
C:\WINNT\System32\WBEM\WinMgmt.exe
C:\Program Files\Logitech\MouseWare\system\em_exec.exe
C:\Program Files\AVPersonal\AVGNT.EXE
C:\WINNT\system32\internat.exe
C:\WINNT\system32\taskmgr.exe
C:\WINNT\system32\ntvdm.exe
C:\Program Files\AVPersonal\AVGUARD.EXE
C:\WINNT\notepad.exe
H:\operatemp\HijackThis.exe

We created two archives, both contained non-compressed files only.
The first one contained one file, ip-to-country.csv (http://ip-to-country.webhosting.info - Dec 2,2004 - 2,696,649 Bytes).
The second one contained a whole OpenOffice.org 1.1.4 english installation (155,662,275 Bytes).

The softwares were configured as follow :

7-zip version 3.13 :
→7z format : Ultra, LZMA, Dictionary=32MB, Word size=64
→Zip format : Ultra, Deflate64, Dictionary=64KB, Word size=64

WinAce version 2.5 :
→Ace format : Maximum, Dictionary=4096K, Use Ace 2.0 compression
→Zip format : Maximum

WinRARversion 3.20 :
→RAR format : Best
→Zip format : Best

WinZip 8.1 :
→Zip format : Maximum

Results

First file (ip-to-country.csv) :

Compressor	Size	Time (CPU)
7-Zip, 7z	286579 Bytes (10.6%)	30 s
7-Zip, Zip	379264 Bytes (14.1%)	6 s
WinAce, Ace	403748 Bytes (15%)	4 s
WinAce, Zip	451248 Bytes (16.7%)	<2 s
WinRAR, RAR	329662 Bytes (12.2%)	2 s
WinRAR, Zip	451165 Bytes (16.7%)	2 s
WinZip, Zip	451248 Bytes (16.7%)	<2 s

Second file (OpenOffice.org) :

Compressor	Size	Time (CPU)
7-Zip, 7z	43433894 Bytes (27.9%)	10 min 30 s
7-Zip, Zip	64514938 Bytes (41.4%)	4 min 10 s
WinAce, Ace	49408901 Bytes (31.7%)	4 min 17 s
WinAce, Zip	not done	-
WinRAR, RAR	53636151 Bytes (34.5%)	2 min 28 s
WinRAR, Zip	not done	-
WinZip, Zip	67681339 Bytes (43.5%)	1 min 20 s

Conclusions

7-Zip does achieve what it claims to be able to do : the 7z format makes substantially smaller archives than other popular formats (Zip, RAR and Ace), and 7-Zip is also able to compress using the Zip format better than other popular softwares (WinZip, WinRAR and WinACE).
Its biggest drawback is its slowness, however its decompression speed (30 s for the second 7z archive) is comparable to WinRAR's (31 s for the second RAR archive) or WinAce's (25 s for the second Ace archive), and a bit lower than WinZip's (18 s for the second Zip by 7-Zip archive).
Let's finish by saying 7-Zip is free, and also enables you to create auto-extractible archives (adds around 80 KB to the original archive). You should try it ;)

We should now assess 7-Zip performances on compressed files, for we noticed during our tests that its performances on compressed files seemed way more average.