Computer Hope

Quote from: Dias de verano on February 04, 2009, 02:48:31 AM
First archiving tool to use the ZIP format, maybe.

Yep, that's what I meant- I'm pretty sure both ARC and ARJ are older formats the ZIP... (as confirmed by your soliliquoy)

They are all, pretty much, differently named bundles of implementations of common compression methods, notably the Lempel-Ziv-Welch method, first published in May 1977. You can get LZW libraries for many programming languages and roll your own if you have a mind to.

Is there one that uses Huffman compression? Or is that just another name for LZW?

Quote from: Dias de verano on February 04, 2009, 04:07:03 AM
roll your own if you have a mind to.

Like Microsoft with the old *.??_ files on most of their DMF media. I think the most annoying thing about the old (<DOS 6.22) EXPAND tool was that it didn't support wildcards (newer versions did, I believe), which meant if you needed to install something manually... it was a pain. But we all know microsoft- most of the time, rather then buy a license or something for most things- they just buy the company, and thus own the product.


And- Of course, a lot of the different implementations can/do use the same algorithms and simply have different file formats. The interesting thing is to say, Zip something, then RAR that ZIP, etc... and continue using different archivers to see how small it will get... which is generally when the space saved with each subsequent compression is less then the space overhead for the format itself.

Why? It amuses me. 

I once created a 50 megapixel 24 bit BMP image consisting of a uniformly black image with one white pixel in the top left hand corner, the file size was around 150 MB, then I compressed it using Winzip's "best" method, I forget just how small it got, about 20 KB I think.

QuoteIs there one that uses Huffman compression? Or is that just another name for LZW?

Huffman published his paper in 1952, his teacher had worked with Shannon (another big name). A variation called adaptive Huffman coding is somewhat related to the LZ family of algorithms, and has the advantage of being patent free. You find Huffman everywhere! Huffman coding today is often used as a "back-end" to some other compression method. DEFLATE (PKZIP's algorithm) and multimedia codecs such as JPEG and MP3 have a front-end model and quantization followed by Huffman coding. Modified Huffman coding is used in fax machines to encode black on white images (bitmaps). It combines the variable length codes of Huffman coding with the coding of repetitive data in run-length encoding.

Quote from: BC_Programmer on February 04, 2009, 02:23:11 AM
Zipping files is a bit more a pain, but still not beyond grasp- pkzip /eX C:\windows\system\*.INI INIS.ZIP

Forgot how weird IE was...

Anyways, I personally just put PKunzip in an empty folder, and drag the ZIP file on top of the PKUnzip program.
Did that on my desktop by accident once....

WinRAR has an anti-virus scan button.

try using Powerarchiver
does lols more than izarc

I prefer 7-Zip, the best free ware.