Tagged Questions

Compression decreases the size of data.

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2
votes
1answer
1k views

Chrome data compression proxy for PC

Google Chrome recently introduced data compression proxy which saves bandwith up to %50 in Chrome beta. (https://developers.google.com/chrome/mobile/docs/data-compression) Sadly it is only available ...
0
votes
1answer
116 views

How to store many files in one file without using compression

If I have a large set of small files it takes Windows a long time to copy them (say five minutes) due to the overhead per file. If I wrap them up in a container it transfers them much faster (say ...
-3
votes
1answer
267 views

Compress text file to tar.bz2 format on Ubuntu

How can I convert a sample.txt (uncompressed) file to sample.tar.bz2 format using Ubuntu 10.04 command shell?
0
votes
1answer
329 views

COMPACT /U command does not decompress large 25GB file

I have a 25GB file that was incorrectly set as NTFS-compressed because the directory where it is had been marked as compressed when it was created. I am trying to decompress it. The file is currently ...
1
vote
3answers
286 views

Check if HTTP calls are gzipped

Assuming that I have an application server (Linux) running on port 80, how can I make sure (with tcpdump, I guess) that all incoming requests are gzipped and all responses are gzipped as well? Also, ...
0
votes
1answer
67 views

Force gpg to use compression?

Odd situation, and I won't go into details about why our present circumstances require it. But, I'm looking for a way to force gpg to use compression. My testing is suggesting that the following ...
4
votes
4answers
3k views

Recursively unzip files where they reside, then delete the archives

I goofed up a setting on the backup software I use. Normally I would have the files from a network share get loaded into a spare drive, compressed into zip folders, then sent off to the offsite hub. ...
8
votes
1answer
7k views

How does 'dictionary size' affect compression?

I know that higher size may lead to better compression ratio and vice verca. But is there a way I can decide better?.. since there are so many choices So far I've noticed dictionary size ≈ file ...
1
vote
2answers
134 views

Size of the compressed image file deteriorates with usage

I have created a VDI file using VirtualBox and need to upload it with compression for other to access. The more I use the virtual machine, the less the compression happens. There is not much of ...
1
vote
1answer
1k views

Video compression with ffmpeg - Constant quality

I am trying to compress videos of 10 seconds at different bitrates with ffmpeg. My aim is to obtain the same video at different qualities (from very low to very high). I don't want to touch audio part ...
-1
votes
2answers
416 views

Looking for a way to compress, encrypt, split, and upload data on Linux for backups to multiple clouds

As the title says, I'm looking for a way in Ubuntu/Linux to compress, encrypt, split, and upload data for backups across multiple clouds. I have grabbed multiple cloud accounts for free ranging ...
1
vote
1answer
1k views

avconv mkv to mkv with audio compression bug

In order to make quality tests, I would like to compress the audio part (to a low bitrate) of a matroska file without damaging video. Audio codec is AAC and video codec is H264. I am using avconv on ...
1
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2answers
106 views

How to extract such a compressed file?

I have been asked to extract a ZIP file having in it 3 tar files and each tar file contains around 3000 gz files. I had to extract the main ZIP file first then extract the tar files second then ...
0
votes
1answer
387 views

Windows: Automated PDF compression (Hot folder)

In Windows, is there a way to monitor a folder and automatically compress a PDF that is placed in it? (by compression, I mean make a PDF smaller (I.e. not zip it), similar to using the reduce file ...
0
votes
0answers
67 views

How to compress 2 (apple) disk images of different backups of the same drive?

So I have backed up my Macintosh HD at different instances to DMG files. I would like to compress them but when I try to make an archive it simply compresses each image, without recognizing the ...
0
votes
1answer
283 views

Differences between DMG and various Zip-like formats?

For my everyday work, I have a few DMG files that I keep on cloud storage. At the beginning of the day, I download my DMGs, convert them from Compressed to Read/Write using Disk Utility (OSX). At ...
1
vote
0answers
283 views

Compressing files over the network with WINRAR - read error

I have 3.6 TB of backup files on a NAS that need to stay together (they are a full and a months worth of incrementals - the latter is only useful with the former) - but I need to move them off the NAS ...
0
votes
1answer
43 views

What is “crossflow compression”?

I came across the term "crossflow compression" several times while reading about WAN optimization techniques. The only elaboration I've seen is that it refers to "compression across various flows", ...
0
votes
2answers
2k views

Zip many files into several archives

Running Linux. I have a directory of around 150 large CSV files; simply doing a zip -9 on them results in a monolithic file that is still too large. I would like it to simply zip them in maybe four or ...
0
votes
3answers
172 views

Untar multiple files at once?

I'm on Windows 7 and have a number of .tar files with the following names: .tar-aa .tar-bb .tar-cc ... The tar files contain a large backup directory which is broken up into chunks of 250MBs each. ...
-1
votes
2answers
141 views

Compress a remote folder in Linux

I'm a Linux newbie and I'm trying to zip a folder which exists on a remote host and export it to another remote host. A quick Google search lead me to tar/gzip and rsync options but I'm not sure how ...
0
votes
2answers
246 views

Good way to reduce number of colors in a PDF file?

I have pages of handwritten notes that I decided to scan to a PDF. Somehow, 153 pages of notes turned into a 156.4 MB PDF file. The notes are scanned in color because I used four different colors: ...
0
votes
1answer
415 views

Is it possible to recursively list zip file contents with 7 zip without extracting

Similar to this question I have a very large zip file which contains other zip files, folders, and files. I want to use 7-zip to extract a list of file names from it, recursing into subfolders and zip ...
3
votes
2answers
201 views

Is there a client impact to server side NTFS compression?

One of a our file servers at work is being compressed with NTFS compression. I've read about it being generally inadvisable on servers. But I've not found anything the states where the ...
1
vote
3answers
838 views

powershell create zip from log files

How can I move log files to zip archives with System.IO.Compression.FileSystem in PowerShell? I have more folders with log files per application: app1logfolder |-app1_20130507.log ...
0
votes
1answer
60 views

mod_deflate - possible to compress 1k or higher only? cache?

Is there a way to tell mod_deflate in .htaccess to only compress files if they are at least 1kb? Also, can it cache compression results? Once it compresses a file, I want it to use that again instead ...
1
vote
2answers
240 views

When compressing a file on command prompt with RAR command, how to stop the process without cancelling it?

I used the following command: rar a -m2 file.rar *.xml \\myroute\ I want to stop the process on the file that have already been processed i.e. using Ctrl + C will cancel the process but not finish ...
2
votes
0answers
155 views

Difference between lzip, 7z and zipx [closed]

I would like to know what is the difference between the algorithms used in these three compression schemes. I found that all three of them are based on LZMA. But I would like to know what makes them ...
0
votes
1answer
1k views

Can't view files from within WinRar (Win7 x64)

I have an issue with WinRar (64 bit version) on Windows 7 (x64) that is similar to the one described in another open question on this website Link to the same issue on this site (unanswered) However, ...
0
votes
2answers
516 views

What is the difference in various commands for compressing files in linux?

What are the commands for compressing files in linux and what are the difference between them? (for example: tar, gzip, rar). I'm working on Linux Mint 11 and doing a script for compressing files. I ...
0
votes
1answer
763 views

What compression algorithms are used by rar? [closed]

I am reading about many compression and archiving techniques.. I am not able to find the compression algorithms that are used by rar. Also I would like to know if rar compresses each file separately ...
0
votes
1answer
766 views

How do I compress a 200MB MOD video file?

My grandpa sends me this huge 200MB video file and asks me to compress it. I bet that there are many ways I can do this. For instance, just guessing some ideas: Use an online conversion tool ...
2
votes
2answers
205 views

Does OS X Preview support saving PDF with JBIG2 compression?

I have a PDF file containing hundreds of BW scannings, that I created on Windows using lossy JBIG2 compression, resulting in a nice 8MB file. I can open that file on OSX with Preview, but if I add ...
1
vote
1answer
208 views

Copying all the files of one extension into a folder

I have been trying to write a .bat program which will find all the files with a given extension, for example *.doc, and will put them into a rar archive. I want all the files to be copied even if ...
0
votes
1answer
288 views

Can we save and resume winrar jobs?

I'm trying to zip a 87 GB folder into multiple volumes, 1 GB each. WinRar is able to do that, however the entire job takes about 20 hours. Is there anyway to save and resume the state of the WinRar ...
1
vote
0answers
2k views

“extra bytes at beginning or within zipfile,” won't open file

I have an 8.3 gig zip containing tons of telescope observation data, but I can't extract no matter what I try. I've tried Archive Manager, unzip, and tried this guy's fix: ...
1
vote
3answers
3k views

Between xz, gzip, and bzip2, which compression algorithim is the most efficient?

Between xz, gzip, and bzip2, which compression algorithm gives the smallest file size and fastest speed when compressing fairly large tarballs?
2
votes
1answer
2k views

Does OS X support disk compression?

I am new to the Mac world. As you may know, NTFS has options to "Compress this drive to save disk space" or "Compress contents to save disk space". I want to know whether OS X supports this feature ...
2
votes
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
vote
3answers
487 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?
1
vote
0answers
307 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
votes
5answers
13k 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
votes
2answers
233 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 ...
0
votes
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
586 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
240 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
votes
2answers
2k 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
701 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
325 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
2k 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 ...