Compression decreases the size of data.

learn more… | top users | synonyms (1)

6
votes
4answers
13k views

How to compress a file in UNIX?

I want to do an ordinary "zip", so my CW3 file becomes CW3.zip. I have tried to use some example commands found on the internet but they don't seem to work. I have tried the following, resulting in ...
2
votes
0answers
24 views

Zipping a text file with sha256 hashes seems too efficient

I have an ASCII-encoded text file where each line has the following structure: XYplorer nn.nn.nnnn [yyyy-mm-dd hh.mm.ss] [S256 S256].zip ↑↑ ↑↑ ↑↑↑↑ ↑↑↑↑ ↑↑ ↑↑ ↑↑ ↑↑ ↑↑ ↑64× ↑64× so a ...
1
vote
3answers
16k views

How to compress a JPG image File

I am trying to send an email with an image attachment. But the image size is 40MB and the attachment size can only be 25MB. How can I compress the size of the image so that I can send it via Email?. I ...
1
vote
2answers
3k views

7-zip command line -p switch not working according to help page

I want to be able to automate the encryption of the file type .pcapng in a windows batch script. My current problem is that I get an error when extracting the encrypted file saying something along the ...
1
vote
1answer
226 views

FFMPEG / libx264: How to specify a variable frame rate but with a maximum?

Instead of providing a fixed frame rate to FFMPEG/libx264 (-r/-framerate), I would like to specify a variable frame rate with a MAXIMUM value, and allow libx264 to down the frame rate as it sees fit. ...
2
votes
2answers
14k views

What is the difference between rar and RAR5 compression?

What is the difference between rar and RAR5 compression ? Which is better for which purpose vs the compression time.
0
votes
1answer
25 views

7zip: compress and copy to destination folder

I am trying to do the following: command line compress a file from C:\TestFolder\file.txt (source location) and on the same command or bat file put that compressed file in (a destination folder) ...
2
votes
6answers
2k views

Any method to batch-compress multiple files?

Does anyone know how multiple files can be GZIP compressed? I have lots of files in a folder and I need to compress them individually. Actually, I've found a way to do it. GZIP command line binary ...
21
votes
3answers
39k views

Is it possible to execute a file after extraction from a 7-Zip self-extracting archive (SFX) archive?

I'm try to make a compressed deploy-able application. Currently I'm taking a set of files that I've published from my IDE (Visual Studio 2008 - WPF published application) and compressing ...
0
votes
1answer
31 views

How to search for a file that is compressed on a external drive from my mac?

My hard drive went on my mac. I replaced it with a new hard drive. I was able to dump all the data from the damaged drive onto an external drive. The dump separates some of the files into word docs ...
2
votes
2answers
3k 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 ...
5
votes
1answer
312 views

How do I use Google data compression proxy on Firefox?

I am using GNU Icecat (GNU version of Mozilla Firefox) on Trisquel GNU/Linux. In order to minimize/optimize data usage while web surfing, I want to use google data compression proxy. So, How do I use ...
2
votes
2answers
797 views

Bloated Excel file

Someone send me an Excel file that's 10MB, and thus causes us email problems. When .zip'ed it goes to under 1MB, so presumably there's something wrong with the Excel sheet but is there any way to ...
-3
votes
1answer
60 views

Why youtube compression algorithm doesn't work well for Minecraft videos?

Minecraft videos have very small entropy : I can play hours to minecraft online exchanging only tens or hundred MB of data with the server, this is an entropy upper bound for Minecraft videos. ...
0
votes
0answers
20 views

GPG with tar.gz at the same time without the full path being packed

I would like to compress and encrypt a folder: tar -cz "/path/to/the/folder/" | gpg --encrypt --passphrase "password" --recipient "mail@mail.mail" > "/destination/package.tar.gz.gpg" When I ...
1
vote
0answers
19 views

Video codec for simple animation? [migrated]

I am generating an animation in Matlab, composed of simple diagrams. The images are characterized by fine structures, strong contrasts and mostly discrete colors, e.g. there are few-pixels wide black ...
-1
votes
1answer
28 views

How can i compressed(winrar) a file using command prompt and the file name of the .rar is the same with the file

i have a autoback.bat file that will automatically backup my database and compress in using winrar application. the problem is i cannot create a rar file that is the same filename of my database. for ...
0
votes
0answers
21 views

LAME doesn't compress MP3 anymore

(I'm running Ubuntu 14.04) Until a while ago the following command used to work fine for compressing MP3 files: find . -iname '*.mp3' -exec sh -c 'lame -b 160 "$0" "$0"-160 && mv "$0"-160 ...
2
votes
0answers
25 views

Disable memory compression in Mac OS X for specific application?

Is there any way to disable the memory compression in Mac OS X for a specific application? I read how to disable it in general at Disable compressed memory in Mac OS 10.9 Mavericks? , but in my case ...
0
votes
1answer
23 views

How to compress an encrypted partition or drive in Windows?

Could someone let me know is there any effective way to compress an encrypted drive or partition in Windows to reduce its size ? Thanks
0
votes
1answer
49 views

What happened to .gzip option in 7-zip?

I am not sure if this is just a coincident or not but I have recently upgraded my OS to Win 10. I noticed only now (after the upgrade) that the .gzip archive format is not available in 7-zip ...
0
votes
2answers
27 views

To open lrzip-compressed in Debian 8.1

I downloaded the SageMath jessie package here but I cannot open it. I get the warning in ArchiveManager Could not open this file type There is no command installed for Tar archive (lrzip-compressed) ...
1
vote
0answers
27 views

Possible bug in 7zip - empty folders extract as empty files

I have a directory structure as follows: Main | |--empty_folder | |--folder | |--example.txt I'm zipping it using the .NET ZipFile.CreateFromDirectory method (but I doubt this has anything to ...
2
votes
3answers
920 views

Create multiple zip files that are not dependent on each other?

I want to compress a folder into multiple zip files of 50MB each but don't want them to be dependent on each other. When I use Winzip and use the split feature it creates one zip file and the others ...
0
votes
0answers
15 views

How to change context menu option for 7zip?

I work a lot with .gzip format and I am wondering if there is a way to change the default "Add to" format in the context from .zip to .gzip.
1
vote
1answer
34 views

how to achieve same compression in linux and windows

I have a example.jar file. I'm trying update a class file in the jar. when I'm packing the class file using jar or zip utility(command line-linux) I tried : jar uf my MyJarFile.jar ...
0
votes
0answers
5 views

Why am I encountering 'Error decoding stream footer' when decompressing using `pixz`?

I compressed a file using tar -pcv input_dir | pixz 8 -p8 > output.tar.xz. When I try to decompress or list the files using pixz -d and pixz -l i encounter the error Error decoding stream footer. ...
0
votes
1answer
15 views

decompress multiples pdf files without using tmp files?

I have more than 100.000 pdf files I want to decompress it, then recompress theme all in one archive file to save space. all i found is: ls | xargs -P 4 -n 1 -I {} qpdf --stream-data=uncompress {} ...
-1
votes
0answers
27 views

Strange model of zip split files

I have some zip splited files, with random sizes, and named as: file 1.zip file 2.zip file 3.zip.... I try unzip this files with the programs winzip, winrar and 7-zip, but when i click in the first ...
19
votes
2answers
13k views

Is zip's encryption really bad?

The standard advice for many years regarding compression and encryption has been that the encryption strength of zip is bad. Is this really the case in this day and age? I read this article about ...
17
votes
3answers
54k views

What are the best options to use when compressing files using 7 Zip?

I often have to gather log files and upload them to a central server (Owned by another company). The central server has a size limit of the file, so I am trying to create the smallest file possible ...
11
votes
9answers
29k views

Highest compression for files(for web transfer)?

I have seen some highly compressed files around, such as 700MB of data compressed to around 30-50MB. But how do you get such compressed files? I have tried using software like WinRAR and 7Zip but ...
2
votes
1answer
107 views

Batch command to archive folders with content using WinRaR

I have lot of folders in the root "C:\Test\Archiv\" (more than 1000). To be more specific, I get one every hour. They are named as following : ay %year% m %month% d %day% h%hour% In each folders are ...
1
vote
1answer
28 views

rar - command line switch for exclude compress but store?

Assuming I have few files like : --- +Royi | +---1.txt +---2.txt +---3.Avi +---4.mp4 +---5.docx looking at : rar a -r -m1 Royi myArchive.rar This will shrink all ...
0
votes
0answers
44 views

Why is none of my Mac memory compressed?

I am constantly up against the 16GB physical memory barrier on my mac. I have looked in Activity Monitor and ZERO memory is compressed. I would like to have OS/X be aggressive in compressing - how ...
10
votes
5answers
9k views

Mac OS X not reporting directory sizes correctly?

In Finder, I've noticed that if I duplicate some .app files (in the Applications folder), Finder will show that the duplicate .app file is not the same size as the original. This file size ...
1
vote
1answer
56 views

Compress large CSV FIle? (500MB)

I have a CSV-File which is 500MB of size. I am searching for a way to compress is to it smallest possible size. I actually received the file back then in a ZIP-Folder which was only about 50MB of ...
2
votes
1answer
50 views

Why does 7-Zip's compression speed lower over time?

I'm busy backing up my local server files, which amounts to just under 4GB of data in ~295000 files. I selected 7z as the format, and set the level to Store. The process started pretty quickly, but ...
0
votes
0answers
35 views

What are all parameters to get the highest compression ratio for animation from ffmpeg x265?

Ok. I'll use -crf 51 (-crf 61, -crf 10 or any other), -preset placebo, -keyint=-1 (only one keyframe in the start). -allow-non-conformance (I am not sure if this is work with libx265). -ref 16, ...
0
votes
1answer
50 views

How do I zip files with the same name?

I'm on a Mac OS X 10.10.4 I need this: Detecting files with the same name, but different extension. (aaa.ai, aaa.eps, aaa.pdf and bbb.ai, bbb,eps, bbb.pdf and so on) Compressing those with the same ...
40
votes
4answers
19k views

How does NTFS compression affect performance?

I've heard that NTFS compression can reduce performance due to extra CPU usage, but I've read reports that it may actually increase performance because of reduced disk reads. How exactly does NTFS ...
15
votes
6answers
13k views

.tar files without directory structure

I'm .taring some files with the path example/super_user/Output.*. The resulting .tar looks like this: + example + super_user - Output.zip - Output.xml - Output.txt ...
0
votes
1answer
41 views

Which level of compression should I use a .iso file [duplicate]

I have a .iso file on my hard drive (on a windows 8 pc) and it is really big (something like 16 GB). I was trying to compress it (using 7-zip) so it could fit on a DVD-R. But when it finished ...
2
votes
2answers
77 views

How to compress extremely large file in place

I need to compress a 646.4GB file on a 1TB external HDD. This HDD currently has about 238.6GB free. However, since the straightforward compression methods create a new file, I'll not be able to ...
122
votes
6answers
243k views

How to decompress a .bz2 file

I have a file as: filename.bz2, but I can't figure out how to decompress it. I tried several methods, none of them seems work. I have tried the command: tar xvjf filename.tar.bz2, but it didn't work ...
1
vote
1answer
4k views

7-Zip: Unsupported Compression Method while trying to extract a zipx file that consists of JPEGs

A zipx file I received consists of .csv files and .jpeg files. I used 7-zip to extract them. While the .csv files were sucessfully extracted, the JPEG files didn't. The error was something like this ...
0
votes
4answers
94 views

How to open tar gz file created using tar piped to gzip

I wanted to generate a tar gz file with the highest compression level, and I followed the solution from http://superuser.com/a/546509/461740: tar cv /path/to/directory | gzip -9 > file.tar.gz ...
0
votes
1answer
42 views

.zip corrupted on Mac

I've got a .zip file of approx. 20GB. (20,497,570,063 bytes) I am trying to uncompress it but both Archive Utility and Terminal are failing to do so. Archive Utility is giving error 2 (no such file ...
68
votes
7answers
20k views

Compress and then encrypt, or vice-versa?

I am writing a VPN system which encrypts (AES256) its traffic across the net (Why write my own when there are 1,000,001 others already out there? Well, mine is a special one for a specific task that ...
0
votes
0answers
25 views

regex search compressed password protected files

I have a repository of a few million large text files. I need to regex search them on a regular basis. Because they are large, I use gzip to compress them and zgrep to search them. I have been asked ...