What is the difference between .rar and .zip, and why do so many people use .rar?
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Anonymous2006-04-18 15:09
A zip compresses each file individually, and rar treats all your files as one and compresses that. Rar tends to get better compression ratios for that reason, but if you want to remove just one file from a large rar file, expect to wait a while if the file's at the end of the list.
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Anonymous2006-04-18 15:09
Rar can be used to split a file into multiple files. Like you can have two 500mb rars that contain a 1Gb iso.
Rar is just a different compression algorithm which is proven to have better compression than zip. Most modern programs, such as winzip, winrar, or 7zip, can decompress both formats, so there's generally no trouble with using either.
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Anonymous2006-04-18 18:43
Zip decompression is fast, but rar is omg 1337.
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Anonymous2006-04-18 19:02
>>1
RAR compresses more, supports more features (solid compression, authentication, etc), has a good password protection (AES-128), WinRAR may replace WinZIP but not the other way, and other reasons.
>>2
Rar treats all your files as one, but only if you want so. It gets better compression ratios regardless of that.
What? Zip has been supporting volumes for as long as I can remember. It had it at least as early as 1990, if not before. So did ARJ, LHA, and whatever else was floating around back then.
Have you used pkzip? No? Then you don't have a clue about zip's history, kthx.
Also, you can emulate solid compression with zip too (zip without compression, then super zip the result), but it's a PITA, so most people use more modern formats.
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Anonymous2006-04-19 4:52
pkzip was leet. I still remember when winzip was nothing more than a frontend to pkzip, and you had to specify the location of pkzip.exe in the settings.
Good compression takes a looong while to compress though.
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Anonymous2006-04-19 9:42
>>9
I've used PKZIP, ARJ, LHArc, AIN, JAR, ACE and other compressors in the past, until I sit with RAR and 7-Zip. Until recently, the popular ZIP clients usually had flaky multivolume support.
Yeah, of course you can emulate solid compression, but it blows, especially when you can rar a -r -m5 -mdG -s your files in one step.
>>10
BZIP2 is a great algorithm, but tar leaves a lot to be desired. An archiver is fine too.
Open sauce compressors/archivers 7-Zip and TAR+BZIP2 have one problem: they lack a standard CLI syntax, something RAR, ARJ, ACE, JAR, AIN, and so many others always had. 7-Zip is almost there but it has a lot of ugly gotchas.
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Anonymous2006-04-19 10:01
The standard syntax is GNU syntax. 7zip fails at this, and doesn't provide any docs so you have to guess at how to use it.
What's wrong with tar?
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Anonymous2006-04-19 10:33
So, for general purpose archiving over a variety of formats including video, images, text, music, and pure binary/random data which program averages the best compression ratio? Which program is the most popular archiver?
Also, soon I'm going to be distributing a large torrent of PSD and PNG images totalling over 500mb. What will shrink it the best?
The de facto standard syntax for archivers, i.e. the syntax most archivers used, from LHA to RAR, from ARJ to ACE. It's made of consistent and simple. Just ARCHIVER <command> [-option [-option2 [...]]] /*i.e. not -ksdfjahsdfuliewf and options can be multicharacter and not need --*/ <archive.ARC> [files /*default * without recursion*/] . Commands are usually a(dd), (e)x(tract), d(elete), etc., options are usually -r(ecurse), -v(olume)NumberUnit, -s(olid), etc.
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Anonymous2006-04-19 11:56
"but tar leaves a lot to be desired"
possibly because tar isn't a compression algorithm at all! it just packages up a lot of files into one .tar file, preserving things like the modification times and file permissions. the .tar file is THEN compressed, usually with gzip to make a .tar.gz or .tgz 'tarball', or with bzip2 to make a .tar.bz2 or .tbz
"So, for general purpose archiving over a variety of formats including video, images, text, music, and pure binary/random data which program averages the best compression ratio? Which program is the most popular archiver?"
The impression I get from most sources is rar offers the best compression. however zip is by far the most common, present on all windows xp systems, all major linux distributions, and likely to be on most older windows systems (I can't speak for mac, sorry). if your target is *ix systems only, bzip2 offers the best combination of good compression and near-certain presence on the client.
"Also, soon I'm going to be distributing a large torrent of PSD and PNG images totalling over 500mb. What will shrink it the best?"
well, both psd and png images are already compressed (losslessly), meaning whatever compression you use, don't expect much, so you may as well ignore compression ratio and go with zip, as that's the most widely supported
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Anonymous2006-04-19 13:45
>>17 possibly because tar isn't a compression algorithm at all!
Lol duh, do you think I don't know that? I meant as an archiver. When I said "BZIP2 is a great algorithm, but TAR leaves a lot to be desired" I meant we can have good compression but the archiver lacks features.
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Anonymous2006-04-19 13:48
I used the new Enchanced Deflate algorithm in WinZip 9 for a while. It worked for me, but if I sent a ZIP to a friend they got corrupt files even when using the same version of WinZip as me. Now I only use normal compression with WinZip, or I just use RAR files.
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Anonymous2006-04-19 15:34
Also, soon I'm going to be distributing a large torrent of PSD and PNG images totalling over 500mb. What will shrink it the best?
The files are already compressed. Just torrent them as a directory, it's not like torrents can only contain a single file.
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Anonymous2006-04-19 16:44
>>17 >>20
Even though the individual files are compressed, if they get stuck together and compressed as a whole - like a tarball - couldn't there be even more compression?
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Anonymous2006-04-19 17:09
>>21
Maybe you'd save people a few seconds downloading, but then they'd just have to spend a couple extra seconds decompressing things.
Although PSDs apparently only have RLE compression, so RAR/7zipping them probably isn't a bad idea. For PNGs it's pointless though.
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Anonymous2006-04-19 18:25
PSDs came from Adobe. You know they will be bad.
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Anonymous2006-04-19 19:35
Actually, if many images are similar, like often happens with CG sets, the smallest file can be made by converting everything to BMP and solid compressing them with RAR or 7zip.
I've seen 7zips that were 1/4 the size of the same images pngcrushed.