7-Zip Ultra Compression

[t0rek]

Do you guys use the 7-Zip Ultra compression or just the normal one? That thing sucks too much RAM but does it worth it? Due to the PC I'm currently using has only 256 Mb of RAM I can't test it.

I'm interested to see a compression comparison using an Ocarina of Time ROM with both normal and Ultra compression settings. Someone please?

[Iconoclast]

There are four kinds of archives that I know of (probably more than four): .zip, .rar, .7z, and .ace.

Out of these two, I'd say RAR and 7Z are the best in compression strength. Usually, 7z compresses better, but I've found instances where RAR beats it by a few bytes.

Do understand, though: Project64 cannot currently read ROMs in 7z archives, only either zip or uncompressed. The most thorough way to compress an N64 ROM is to use 7-Zip to do it (not compressed zipped folders that comes with WinXP), and generate a zip archive using the Deflate compression method setting on Ultra compression level. Deflate64 is even stronger, but most simplistic archiving programs can't even read it, let alone emulators. Are you sure you can't compress using Ultra? Have you tried it, or did you just get that from 7-zip's "Memory Used to Compress?"

[Toasty]

Legend of Zelda, The - Ocarina of Time (U) (V1.0) [!] (original size: 33,554,432 bytes) compresses like so:

7z Ultra - 23,071,804 bytes
7z Maximum - 23,071,765 bytes
7z Normal - 23,264,354 bytes
7z Fast - 24,242,252 bytes
7z Fastest - 25,197,701 bytes
7z Store - 33,554,640 bytes

Your eyes kid you not; maximum compressed slightly better than ultra in this instance.

[Iconoclast]

What's up with that? I'd like to know why it did that for future archiving.

[t0rek]

Thanks a lot Toasty, it seems that at least in ROM compressing the difference achieved is minimal

For Iconoplast:

is not that I cannot use Ultra compression setting, is just that if used it will take aeons because of my little RAM amount (the HDD started to use the pagefile in a insanely way when I tried). BTW this thread was about 7-zip format internal differences, and AFAIK Project64 1.7 will include 7-zip support so I was curious about it

[ScottJC]

7z's compression difference isn't worth the extra time it takes to compute; 7z's main strength is the Solid archives to store multiple files of similar content, but rar can do that too and probably faster so I'd say its not really worth the bother.

[Doomulation]

I just select Ultra and max out the settings and go. It doesn't really bother me; it doesn't take long, so I always tend to use 7z at maximum compression.

[Clements]

I have 7zip and WinRAR installed on my system, and I use them for different purposes. I use 7zip with the Ultra setting to store similar files with solid archiving over a long term, and RAR to store files that I wish to access regularly that are large when uncompressed.

Accessing an individual file from within a solid RAR archive without fully decompressing the archive is much faster than with a solid 7zip archive, but in certain instances where the files are similar enough, 7zip can produce a much smaller archive so can be good for storage for long term such as CD/DVD etc backups.

[Toasty]

7zip does seem to perform significantly better with similar files in a solid archive. When compressing four versions of 007 - The World is Not Enough into an archive, 7zip Ultra compression with solid archive achieved a size of 25,459,790 bytes, while WinRAR Best compression with solid archive only managed a bulky 102,312,712 bytes. Other situations may be different though.

[smcd]

There is sometimes a good difference in using LZMA versus PPMd methods - even on some binary files.