Compression decreases the size of data.

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1answer
494 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 ...
-1
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3answers
2k 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
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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 ...
0
votes
4answers
3k 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
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1answer
197 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
172 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
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1answer
243 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 ...
40
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4answers
73k 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 ...
0
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1answer
643 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. ...
22
votes
5answers
1k 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 ...
-1
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0answers
228 views

How to have self-extracting file that executes an .EXE post-uncompression? [on hold]

How do I compress a folder of files to create a self-extracting .EXE that immediately executes one of the extracted files post-compression?
0
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0answers
212 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 ...
0
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3answers
4k 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 ...
2
votes
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? ...
0
votes
1answer
576 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 ...
31
votes
5answers
2k 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?
7
votes
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 ...
2
votes
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) ...
1
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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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4answers
14k 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 ...
0
votes
1answer
578 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 ...
3
votes
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?
2
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1answer
4k views

Identifiying a zip file that is not really a zip file

I have several files that a 3rd party program generated that have a .zip extension, however neither windows nor 7zip can extract it. In 7zip it does show me the file name of the uncompressed file ...
5
votes
5answers
11k views

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 ...
1
vote
1answer
341 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 ...
6
votes
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 ...
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3answers
263 views

Unix tar compressed folder not opening on windows

I used command tar -cvzf upload.tar upload to compress my upload folder, but when i'll extract it on widows using 7-Zip it shows up as just a single file, not folder. And the uplad folder isn't ...
2
votes
2answers
875 views

How do I unzip a file with PPMd compression: I have the error “PPMd method not supported”

Ubuntu/Windows 7 user here, I have a zip file that I am trying to extract. In windows I get an error. In Ubuntu, the archive manager I get a "PPMd method is not supported" I read about 'e', a ...
2
votes
2answers
1k views

Linux zram (compcache) + SwapCached

I have a question about zram + swapcached. I know that zram is a compressed swap in memory, but linux use it's own internal SwapCached area to store recent swap pages also in memory. I have a 512MB ...
2
votes
1answer
1k views

Zip/gzip compression ratio much less in Linux than in Windows

I have a bunch of very huge files located on a Linux machine that I would like to compress and save some space. I have tried using the tar/gzip combination and I have noticed that the compression ...
7
votes
5answers
3k views

Whatever happened to compressed read/write filesystems?

Back in the 90s, my home computer was an Acorn Archimedes. It had on it a piece of software called ArcFS, which allowed you to create compressed archives, a bit like zip files. Unlike zip files, they ...
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2answers
2k views

How do I compress a vmlinux kernel into vmlinuz?

The question is pretty much summed up by the title - I've just built a kernel which has generated the vmlinux output file. How do I compress this into a vmlinuz image?
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2answers
502 views

Is there a way to determine the original size or file count of a 7-zip archive?

I know that when I compress an archive with the 7za utility, it gives me stats like the number of files processed and the amount of bytes processed (the original size of the data). Is it possible, ...
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2answers
237 views

Looking for Unix tool/script that, given an input path, will compress every batch of uncompressed 100MB text files into a single gzip file

I have a dump of thousands of small text files (1-5MB) large, each containing lines of text. I need to "batch" them up, so that each batch is of a fixed size - say 100MB, and compress that batch. Now ...
2
votes
1answer
139 views

JPG compression setting for consumer-quality vacation photos?

When I'm saving a JPG file, Paint Shop Pro (Windows) and Gimp (Linux) show a pop-up to choose the JPG compression level. The apps have something like 85 as default value, and I think reducing the ...
0
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2answers
1k views

Advanced file compression software for Mac OSX

Back when I used Windows, I always used WinRAR for file compression and decompression. It had a fair amount of options like 'just storage' vs 'hard compression', password protection and archive type. ...
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1answer
266 views

Compression of large files

I am trying to compress large datasets (from 15-400 GB each). I am looking for the best compression software for Mac that has High compression rate. Is fast I have tried 7zX, which has excellent ...
2
votes
1answer
1k views

Set default options for WinRar

Is there some method for setting the default extraction properties for WinRar? I want to make it so that I can open a rar file, press Alt-W and have it decompress to a default location and have it ...
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2answers
285 views

AAC 256kbit to MP3 320kbit conversion. I know it's lossy, but how?

Has anyone ever transcoded music from a high-quality aac to an mp3 (or vice-versa). The internet is full of people who say this should never be done, but apart from the theoretical standpoint that you ...
6
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2answers
3k views

Multithreaded support in 7za

(I posted this first on serverfault, but then I realized it probably belongs here.) I'm trying compress a very large text file using 7za (p7zip) 9.20. The -mmt option doesn't seem to have any effect. ...
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3answers
8k 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 ...
12
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2answers
32k views

Different compression methods in 7zip: Which is best suited for what task?

So there are different compression methods in 7zip. Which method is best suited for what task? For example: One difference between LZMA and LZMA2 is I can choose all my cpu cores, whereas in LZMA 2 ...
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2answers
8k views

Convert old videos to have smaller sizes

I have some videos from a few years ago,with various formats, such as avi, mpg, wmv, rm, rmvb, .... Their sizes are huge(more than 500 MB, and sometimes > 1GB). Given there may likely be some ...
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1answer
74 views

Is there a compression method for compressing a group of very similar files, without archiving them?

I want to compress a large nuber of files that have near identical headers, and also some data, however I do not wish to archive them, nor do I wish to zip them individually(because the copression ...
1
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1answer
822 views

Batch compress mp3 while retaining file and directory structure to new target

I have a master directory of music which is organised using subdirectories. My new (cheap) MP3 only holds 8GB so I wish to make a reduced version of my music with a lower bitrate. Is there a free ...
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0answers
692 views

Set .png default compression in Photoshop CS6

Is there a possibility to set .png default compression options to "NONE / fast"? Whenever I try to save as .png, the default option is set to "smallest / slow".
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vote
1answer
4k views

Batch resize and compress PDF files

I need a way to size down and compress batches of PDF files. I'd prefer to do this on Windows, but Linux would be fine if it meant a smoother workflow. I know that there's programs such as NitroPDF ...
0
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5answers
2k views

Zip multiple folders indvidually, automatically

I have folders full of photos within category folders eg holidays spain france italy family son daugher christmas 2010 2011 ... except much longer ... there are about 100 folders. I need ...
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2answers
5k views

How to extract .arc files

I downloaded a software from the internet which is in .arc format. How can I extract the files on MAC? The arc file is 4GB, but I believe it will be 30 GB when extracted.
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2answers
377 views

How to further optimize PDF filesize?

I've been combining PDFs into a single file with Acrobat X Standard and have been able to get a 30-page document down to ~8MB. I've been seeing numerous similar documents that are just as, if not more ...