Compression decreases the size of data.

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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 ...
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5answers
4k 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 ...
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0answers
70 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) ...
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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 ...
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1answer
202 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 ...
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2answers
289 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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1answer
106 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 ...
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1answer
265 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 ...
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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
41 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 ...
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4answers
11k 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 ...
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3answers
6k 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 ...
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2answers
672 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
374 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
175 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
89 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 ...
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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 ...
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2answers
5k 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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2answers
641 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 ...
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1answer
83 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 ...
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1answer
84 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 ...
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1answer
152 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" ...
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1answer
188 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 ...
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1answer
591 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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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 ...
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2answers
2k 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 ...
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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) ? ...
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1answer
239 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 ...
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1answer
200 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 ...
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1answer
366 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 ...
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4answers
111k 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 ...
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1answer
828 views

General Compressibility Of Various File Formats [closed]

Has anyone come across list of which file formats generally compress well (in general algorithms)? Generally, text files .txt compress well, and media-files (.mp3, .avi, etc) do not compress well. ...
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5answers
2k views

Why doesn't Gzip compression eliminate duplicate chunks of data?

I just did a little experiment where I created a tar archive with duplicate files to see if it would be compressed, to my awe, it was not! Details follow (results indented for reading pleasure): $ dd ...
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0answers
229 views

Is it possible to recover partial compressed files?

Of the most popular compression methods (7z, RAR, Zip, GZip) is there any of them that allows to retrieve the uncompressed data from a partial file? Imagine there is only one compressed file, and it ...
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3answers
6k views

How to compress / reduce the size of JPEG photos for archiving? [closed]

I have 50,000 high resolution JPEG photos, where a couple of them might occasionally be needed, about once a year. I wanted to zip them to save disk space, except that zipping gives no space benefit ...
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3answers
2k views

Why does a zip file appear larger than the source file especially when it is text?

I have a text file that is 19 bytes in size and having compressed the file using zip and 7zip, it appears to be larger. I had a read of the question on Why is a 7zipped file larger than the raw file? ...
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1answer
679 views

pdftk: Compressing a bunch of PDFs en masse/in batch while keeping the filenames?

I have a rather simple problem. I have a lot of PDFs that I want to compress, all grouped by college class. I don't have the time or energy to manually run the compress command when I know I can ...
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5answers
3k views

Why is a 7zipped file larger than the raw file? [duplicate]

Possible Duplicate: Why doesn't ZIP Compression compress anything? I tried 7zipping an .exe file but it actually became larger. Is this the expected result?
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2answers
2k views

Progressive JPEG quality compare to normal JPEG?

I'm trying to convert some BMP files into JPEG format at highest quality (Q = 100) until I realize there is a "Progressive" option here. One of my BMP file is 2.9MB. After converting to JPEG format ...
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3answers
2k views

rsync an already compressed file

will rysnc -z have any compression advantage if the input file is already gzipped? I have a large 100GB compressed file to send over the network across servers and it consistently failed(broken pipe) ...
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1answer
2k views

Is there an rsync alternative, that stores compressed and encrypted?

I'm looking for a suitable off-site backup / file synchronization solution. Both local client and remote server run linux. Storage space on the server is limited, bandwidth between client and server ...
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3answers
18k views

How to highly compress files

I want to learn how to highly compress a file. I have downloaded files whose compressed size was 4 GB, and after extracting they became 10 GB. Which software do I need to use for such high ...
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1answer
706 views

Does putting media files in archives help save space?

For example if you used WinRAR or Winzip on .mp3 or .wmv files would it save disk space? I thought the answer was no because the compression was already built into their encoding. But then I red this ...
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2answers
2k views

jpeg: reduce picture size without changing resolution and quality

I'm trying to reduce file size of a bunch of JPEG files, say 1280x720. Without changing the resolution and the visual quality much, what are the recommended approach?
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5answers
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Reduce .wav file size

I am required by a distance education language course to record some audio and submit it. However, they are being absolutely unreasonable. I am only allowed to attach a file that is 5mb while my ...
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1answer
370 views

Does compressing all files on a 50% full disk partition slow down performance?

Windows Vista SP2, (uncompressed 100 GB Drive C is 50% full and Windows file indexing is on): Drive C, where all the program files, \Windows folder and all my data is located is half full, enjoys ...
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3answers
5k views

Is it safe (or advisable) to compress Windows Installer folder via NTFS compression?

The title pretty much explains the question. Aside from the obvious (speed), is it generally safe or advisable to compress via NTFS compression the C:\Windows\Installer folder given that it's within ...