Compression decreases the size of data.

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2answers
2k views

gzip several files in different directories and copy to new directory

I'm working with several files that are located in different directories that I need to compress into individual .gz files. I also need to move the compressed files to a single directory while leaving ...
1
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3answers
510 views

What is the equivalent unix command to a Mac OSX “Compress” menu action?

When I right-click a file in Mac OSX and select "Compress 'File Name'", what is the equivalent bash or terminal command to get the same result? Is it just gzip -9 /path/to/filename?
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0answers
319 views

Wear leveling, Compression and Journaling Filesystem for SD cards [closed]

I'm looking for the ideal filesystem to place in my SD card holding the root of the operating system. The FS must support journaling in order to provide better data safeness; compression is also ...
4
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5answers
14k views

What if I checked the box “Compress this drive to save disk space” on an SSD?

I was wondering how it would effect an SSD if this was checked: I was just curious whether it would save my SSD disk space?
4
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2answers
238 views

Compress Similar Files Efficiently

I frequently have the need to compress files that are very similar to each other. Currently I use 7Zip, which compresses a 16GB file down to 1.2GB in about 35 minutes using 8 cores with Ultra ...
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1answer
1k views

Split a folder of files into multiple zip files based on size or # of files

My problem is that the file uploader I'm working with will only allow a zip file with a size of 10mb or less. Unfortunately, I have thousands of files that need to be processed and I do this by ...
2
votes
1answer
600 views

Why is ZFS gzip-9 compression so much worse than actually using zip files?

I am working with some very large packet capture files (~150GB across 30 files) but because of how highly redundant packet captures are, these compress to ~7% (14.29x) of their originally file size ...
2
votes
2answers
243 views

Compress an attachment in my mailclient inside my INBOX?

I got a lot of emails with uncompressed formats (like bmp, txt, ...) that I want to keep inside my IMAP-inbox, so I can access them from all my devices (Windows, Linux, ios, Android). Those emails ...
2
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2answers
3k views

How to zip multiple folders in 7zip?

I have a folder, lets say, MAIN. Inside this folder, there are many folders(say f1,f2,f2...) which has subfolders and files in them. Now I need to zip these folders(f1,f2,f3...) and their contents ...
4
votes
2answers
743 views

Create a .png with zopfli

I wanted to give zopfli a try since I have some static .png's that I am using on a website. I see how I can create .gz and .deflate-files. But how can I create a png that can be displayed in FF, ...
2
votes
2answers
331 views

Deduplicate Files inside multiple .tar.gz archives

I take a nightly backup from my Webhosting service as .tar.gz. The Data changed is very little each night (<10MB). I would like to archive these files and deduplicate (solid compression) files ...
2
votes
1answer
3k views

Shell Script to GZIP files without overwrite .gz files

I'm trying to create a shell script which receive as first parameter of a path to a folder which I would like to compress all files using gzip without overwrite the .gz files that already exist in ...
2
votes
1answer
313 views

How would Apache or Compressed HTTP react to a zip bomb?

inspired by Compress a 1GB file into 200_MB? and the related comments: Many webservers today use a zipped HTTP Version (Gzip afaik). How would Apache or any other server react to a zip bomb? Since ...
2
votes
4answers
11k views

Compress a 1GB file into 200_MB?

So I just downloaded MySQL for Windows 64bit which 211.9MB but when I extracted it it is now 1.05GB. How did they do it? They archive wasn't damaged at all nor corrupted. Before (Compressed): ...
0
votes
1answer
476 views

Windows 7 extract and compress zip has been compromised by NCH's Express Zip program. How to fix?

I installed NCH's Express Zip, and now I can no longer use Windows 7's way of extracting and compressing. I would like to get rid of the NCH program and get back the original functionality of windows ...
1
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2answers
161 views

Are there any libraries that determine if a file is worth compressing before being transferred?

I've read that sometimes files like .mp3's or compressed images aren't worth compressing (with zlib for example) because they are already compressed and they'd waste more CPU resources than save ...
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0answers
996 views

How to verify 7zip'd files integrity

For some files I have compressed, I have been looking for a MD5 add-on to 7zip (As I have the MD5's by way of an Explorer Column Handler, in xplorer2); or a CRC Explorer Column Handler (Because 7Zip ...
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1answer
2k views

How do I compress multiple files into one archive using lzma?

Looking at the options of xz and lzma, I can't for the life of me figure out how to compress multiple files into one archive. I know it is possible because I've uncompressed a .lzma file and it opened ...
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0answers
62 views

7zip - How to overwrite a existing file? [duplicate]

Possible Duplicate: How can I overwrite an existing file in 7zip? I'm trying this: 7za.exe a "C:\Disc.7z" "C:\test" -v20000000b -m0=BCJ -bd But if I already have created the file ...
0
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5answers
5k views

How can I overwrite an existing file in 7zip?

I'm trying this: 7za.exe a "C:\Disc.7z" "C:\test" -v20000000b -m0=BCJ -bd But if I already have created the file C:\Disc.7z then 7zip doesn't compress anything and sends me this output: System ...
0
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0answers
73 views

LZMA Based Archiving on Linux

I am trying to build an archiving system. I have tested out LZMA compression algorithm, and it provides very good results. However, I need the ability to add and retrieve(will remain in the archive) ...
0
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1answer
2k views

Unpack NSIS executable

I am trying to decompress a NSIS executable. With the GUI version of 7zip I am able to do this and the exe is listed as: Type = Nsis Method = LZMA:25 Solid = + With the command line version 7za I ...
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2answers
2k views

Synchronizing files using 7zip and the CLI

In the command line, 7zip has the command 'a' to "Add files to archive". But I want to sync the files instead. This is one of the main options in the GUI, but the CLI has disregarded it for some ...
0
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1answer
206 views

Poor compression of compact flash image, even after 0 fill

Problem: I am attempting to create an exact image of a compact flash and then compress the compact flash image for easier storage. The compact flash is not full (~1.5GB used, 32GB size). The problem ...
1
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2answers
324 views

Compressing multiple files into multiple archives?

I have a folder full of pdfs and I'm tired of Winraring each file separately. I don't want to put them all in one archive. Isn't there a command line I can use to make Winrar compress a file with ...
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votes
1answer
107 views

How to achieve the compression level of a PDF scanner

I have one paper scanned into a PDF, which has a size of about 700KB and 300dpi. But if I take a snapshot of the PDF file using DPI settings of 300 as well, the image file (in PNG, JPG, or TIFF) is ...
0
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1answer
274 views

I am trying to zip files individually, but the file type is unknown

I am trying to zip some files with an unknown file type individually. I am using the following code in a batch script to do that: @ECHO OFF FOR %%A IN (bestbuy*nat*component.cpi*) DO "C:\Program ...
2
votes
1answer
67 views

Find out who compressed the files

I received a message that contains a compressed RAR file. How can find out who compressed the files and created RAR file? (the user account or computer name)
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1answer
73 views

Is there any file compression program that supports saving session and resuming when files become inaccessible?

I intend to make one-time backup of ca. 100GB files from NAS. Unfortunately, due to poor design, the backup machine is limited to wireless access with the NAS. I expect the connection to break ...
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0answers
44 views

Archive / compression formats or tools which support multiple file forks or streams?

Lately I've become interested in the ability of several filesystems including Apple's HFS+ and Microsoft's NTFS which support two or more data streams. In Mac terminology these were most widely ...
10
votes
4answers
14k views

How to obtain maximum compression with .tar.gz? [duplicate]

The way i understand the use of tar + gzip is that tar is normally used to consolidate a grouping of files into a single file, then gzip is used to compress that file. I recently learned that tar can ...
6
votes
3answers
7k views

How do I reduce the file size of videos?

I need to reduce the file size of some of my HD videos, since I am running out of storage space. A lower resolution is acceptable, and other methods are welcome. I would prefer a GUI solution, as I am ...
0
votes
2answers
850 views

How to extract and erase the original compressed file on Windows 7?

I wonder whether there is an extractor tool that as well as extract the file contents, erase the original compressed file. Thank you.
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1answer
390 views

How to use Pipe Viewer (pv) for measuring compression progress?

I've been trying to track the progress of the data in a pipe, specifically in a large init script for a minecraft server. How would I go about using pv to get an accurate readout of progress? I've ...
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0answers
176 views

How to unpack a compressed executable without knowing the compression algorithm

I'm not sure if this question was asked. I searched for it and could not find it. How can I unpack a compressed executable without knowing what compression algorithm was used to compress it? For ...
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1answer
93 views

Most space-efficient format for image with large dimensions but few colors?

Recently I have had to scale up the dimensions of a gif image by a factor of 2, this resulted in an increase of the file size by about 8 times. While this is not a complete surprise, I can't help but ...
0
votes
1answer
2k views

Is there a limit to compressed file size on Win XP?

I just compressed 11.6GB of data on my hard drive into a 4GB zip file using Windows XP Compressed Folders, and deleted the original data. I then found that the 4GB zip file is corrupt. Is this simply ...
3
votes
2answers
6k views

Compress files from OS X terminal?

In the Finder, there is this wonderful ability to right click on a file or directory, select compress from the drop-down, and end up with a zipped file. Is it possible to do the same thing from the ...
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votes
2answers
713 views

Compressing PDF files [duplicate]

I have a PDF created from JPEG images colour scanned from a few pages. The file size is very large (> 325 MB) and I don't have access to the original scans (I only have the PDF file). Is there any ...
0
votes
1answer
89 views

Compress snapshot backups with duplicates

I have a set of backups of mostly photos. The directory looks sort of like this: backup/Day1/photos/1.jpg .../2.jpg backup/Day2/photos/2.jpg .../3.jpg ...
-1
votes
1answer
86 views

Why don't mp3 files use better compression techniques? [closed]

For instance, an mp3 can be losslessly compressed with 7zip to about 25% of its original size. I compressed an album and the whole thing is a 1/4 of the size. Each song is about a 1/4 of the size (a ...
3
votes
1answer
154 views

Is a password protected file compressed with Windows XP built-in compression also encrypted?

This seems like a simple question to find an answer for on Google but I'm having no luck, and when sites do mention anything about it, I fear that they are using "password protect" and "encrypt" ...
1
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1answer
220 views

Is it possible to compress without duplication?

Is there a way to compress a set of files without duplicating them (i.e., I want to choose 'compress' and see the files I want compressed disappear into a zip file or other format). I ask because I ...
2
votes
1answer
626 views

ZFS compressed and deduped filesystem on file

I can create squashed filesystems with mksquashfs in this way: mksquashfs dir-1 dir-2 ... dir-n filesystem-on-file.squash -comp xz -Xbcj x86 -Xdict-size 1048576 -b 1024k mksquashfs provides ...
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votes
3answers
3k views

Compress MP3 downloaded from the web?

I recently downloaded a bunch of raw audio streams from the web as MP3s and I realize now that they're huge! 60 MB a song… I would like to compress these, but the other question similar to mine links ...
2
votes
2answers
3k views

How can I use the Btrfs compression option when installing Linux?

I've been trying out the Btrfs with an SSD drive and like the compress option which is set in the fstab. However this only applies to the files created after I have installed the operating system and ...
0
votes
4answers
4k views

Why do large zip files become corrupted so often after downloading?

It seems that when I use a web browser to download a large zip file (2-4gb), I go to unzip it and viola, corrupted. This happens so often. Are browsers not reliable means to download a file (http) ? ...
0
votes
1answer
258 views

Windows crashes when I try to compress large .MOV file from iPhone

I have a 40 minute, 6 gigabyte .MOV file that I transferred from my iPhone to my PC. I need to upload the video to Youtube but the file is too large. When I try to compress the video, my computer will ...
3
votes
1answer
213 views

tar file extraction, why file size reduced

We commonly know that compression is the reduction in size of data in order to save space or transmission time, I should expect bigger size when I extract compressed file. I have downloaded a file in ...
0
votes
1answer
401 views

Create a zip file that doesn't create a folder when opened, Mac OS X

I am wondering if there is any way of easily creating a zip file that contains a bunch of files. However, when I double-click to open this zip file, I do not want it to create a subdirectory with the ...