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Questions tagged [compression]

The re-encoding of a file or data into a form that uses fewer bits of information than the original data.

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Why can’t Mac compress files faster than ~60MB/sec or so?

It seems like this has remained relatively constant over the last 5+ years or at least as long as I have been paying attention. Files on an internal SSD can be copied to other drives much faster… ...
Caleb Burdett's user avatar
1 vote
1 answer
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Could a 163-bytes size difference between the tgz of two different 590mb dirs be caused just from file metadata? Or is the file data diff?

While trying to remove duplicates of MRI readings I am tarring / compressing (tgz) the top-level directory with a mix of executables, pdf, text, dll, and data in proprietary format (but sometimes with ...
smithknown34's user avatar
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How do I compress an encrypted time machine disk image?

I have an archived read-only Time Machine drive sitting on a NAS. It is a straight dump (made with dd) of a CoreStorage encrypted HFS+ hard disk. It's taking up 10TB, and I expect that the much of the ...
Glyph's user avatar
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1 vote
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Unable to compress / zip zero byte files in external exFat drive in Mac OS

Why can't I compress/zip a zero byte file which is located in an external exFat drive in Mac OS ? I keep getting this error, The operation couldn’t be completed. Undefined error: 0. I have some marker ...
anarchy's user avatar
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4 answers
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Is an image as ".jpe" an ordinary JPEG, just with a different file extension?

I have a little dozen images with the file extension *.jpe. All the others are the well-known *.jpg, *.jpeg and so on. Can these images be renamed from *.jpe to *.jpg? Is there any difference to *.jpg?...
Sybil's user avatar
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2 votes
1 answer
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Best compression format for backing up many MacOS files (7Z, GZIP, BZIP2, etc)? [closed]

I want to take a backup of the folder ~/Library/Application Support/MobileSync which houses my iOS Backups on my MacOS computer. To do the backup, I'm planning on archiving this folder with file ...
P A N's user avatar
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1 vote
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What compressed file formats does the Files.app support?

What compressed file formats does the Files.app support extracting from? I can't seem to find any official documentation to this effect. Any trial-and-error tales?
Gothic_Day's user avatar
1 vote
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Compress $HOME Directory Using tar.bz2 | macOS 10.15.7

Not interested in using Time Machine in this case. Trying to backup the $HOME directory and am producing an error at the same location no matter the command so far: ~/Library/Containers/com.apple....
m_antis's user avatar
  • 54
3 votes
1 answer
501 views

How do I compress a file into .xip format?

I wanted to compress the Xcode.app I downloaded from the app store into .xip format. Is it the same as compressing it to .zip and renaming?
Ted's user avatar
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1 answer
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Difference in archive formats?

After a little testing, I can't figure out what the difference is in the archive formats listed in the Preferences > Use archive format. Each time I compress a folder, each one has the same ...
agarza's user avatar
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1 vote
1 answer
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Compress file as .tar.gz instead of .zip

If I right click a file and I compress it I obtain a file.zip. Is it possible to set right click-->compress to produce a file.tar.gz as output? I always have to do it through terminal but many times I'...
Erontado's user avatar
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1 vote
1 answer
1k views

Use gzip to uncompress svgz file: unknown suffix

I tried to uncompress a .svgz file using gzip, but encountered gzip: p1.svgz: unknown suffix -- ignored. $ gzip -d p1.svgz gzip: p1.svgz: unknown suffix -- ignored I added the suffix .gz to the ....
SparkAndShine's user avatar
3 votes
1 answer
524 views

Why does Image Capture scan tiff files with different compression formats?

I'm scanning some old family photos using Image Capture. I want a lossless image using TIFF and LZW compression. What I'm seeing, thanks to the tiffutil -info <file> command, is that the .tiff ...
spyle's user avatar
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5 votes
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What is the full name for LZVN, the compression algorithm?

The LZVN algorithm, like the better-known LZFSE, is introduced in macOS 10.9 for decmpfs. It was discovered in 2014 as a kernelcache compressor before the official WWDC 2016 release of LZFSE, which ...
Mingye Wang's user avatar
2 votes
1 answer
569 views

Is it safe or beneficial to compress a .photoslibrary file?

I am trying to create external backups of all my digital data in case something bad were to happen. Is it safe, or even beneficial, to compress a .photoslibrary file to store on an external device for ...
RyDev's user avatar
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1 vote
0 answers
1k views

Batch compress contents within a folder using Mac Automator

I've seen an automator service that can zip multiple folders into separate zip files: Batch compress multiple folders into individual zip files Can this be modified to enter the folder, compress the ...
Drew_jones's user avatar
3 votes
2 answers
3k views

How to convert non-utf8 encoding to utf-8 encoding during unzip?

I have the same problem which described here. The only difference is I need to do this in MacOS. Basically, all files are encoded in non-utf8 and zipped on Windows. When I unzip it on MacOS, they ...
sgon00's user avatar
  • 2,384
26 votes
2 answers
13k views

APFS - how do I enable transparent compression

How do i enable transparent filesystem compression on any APFS volume? Or check if it is already enabled? I am expecting something similiar to NTFS compressed attribute. According to Wiki it should ...
Sidias-Korrado's user avatar
1 vote
1 answer
2k views

Compressed hidden files are not hidden anymore when uncompressing on Windows

When I zip hidden files and folder and unzip on a Windows PC, they do not remain hidden. I tried to hide them with dot and also with the command chflags hidden. Is there anything I can do? It happens ...
TryingTrying's user avatar
-3 votes
1 answer
1k views

A script to shrink and compress DMG disk images does not seem to work well in my scenario

I'm trying to resize the *.dmg of my MAC OS X installation file because I have only DVD of 4.7 GB and not dual layer disks,at the moment. The problem is that the dmg file is almost 7 GB large and I ...
Marietto's user avatar
20 votes
3 answers
17k views

Tell macOS to only use swap and compressed memory when really needed (macOS 10.14 Mojave)

As disabling swap and/or compressing memory is not recommended and also not a stable option after 10.9 Mavericks (despite the vm setting exists), I'm doomed after few days of running my Mac with my ...
dszakal's user avatar
  • 544
3 votes
2 answers
859 views

How to decompress and run .app?

I'm trying to execute an AppleScript .app thats compressed. unzip -p file.app.zip | open - or open < $(unzip -p file.app.zip) Is this possible?
lily's user avatar
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9 votes
5 answers
6k views

macOS equivalent to the Windows "Compress file/folder content on disk to save space" option

Windows has a useful feature where files can be transparently compressed/decompressed on the fly. This is activated by right-clicking on a File, directory or Disk, selecting Properties and then ...
user1258361's user avatar
2 votes
3 answers
2k views

Is it okay to compress application files? (Especially licensed applications)

I have attempted to research this but given the fact that applications exist to compress other files, I've found it difficult to learn about compressing applications themselves. I presume its okay to ...
Unrelated's user avatar
  • 555
3 votes
3 answers
36k views

Why do the photos on my iPhone 7 seem to be losing quality?

The photo quality is my iPhone 7 is very low. I found out that this may be because I switched on “iCloud Photo Library” a few months earlier, and “Optimize IPhone Store” was selected. Does doing so ...
Trent Raptor's user avatar
-2 votes
1 answer
238 views

How to reduce a PDF size in mac [duplicate]

How can I reduce a PDF size that is very big locally in a Mac
Nicolás Mejía's user avatar
5 votes
2 answers
4k views

How to unzip .xz [duplicate]

How can I unzip a .xz file? Archive utility failed. Is there an app that I should get to do it? (Mac Pro, OS X Yosemite 10.10.5)
Matt's user avatar
  • 749
1 vote
2 answers
251 views

Compression / archival utility which stores the most metadata?

I recently did a backup of a FAT32 disk which contained a lot of diverse data. It contains many media files, many big binary files, and as usual with FAT32, it has all kinds of odd (but potentially ...
GDP2's user avatar
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1 vote
1 answer
3k views

Extract HFS+/HFSX volume from dmg file

Dmg file contains a volume with identifier Apple_HFS, which is compressed with various methods (zlib, bz2, etc.), how can I extract a raw, uncompressed HFS volume from DMG file? Right now, it cannot ...
Michał's user avatar
  • 11
0 votes
2 answers
155 views

Compress attachments in received emails

I regularly receive emails with very large attachments (uncompressed scans, photos, videos, etc.). Obviously, the sender could have done me a favor by compressing the files before sharing. But not ...
Janosh's user avatar
  • 1,111
121 votes
10 answers
226k views

How can I unpack .7z files via MacOS terminal?

Looking to unpack a bunch of files.7z via terminal. Is there a command-line tool built in, available or I shall install an application that comes with a graphical interface?
SuperAtic's user avatar
  • 1,431
2 votes
0 answers
347 views

Can I turn off memory compression for one specific app?

I am using MATLAB on my Mac. Well, MATLAB is running well but not fast -- while there are plenty of free memory, my Mac still compresses MATLAB's memory - from ~2GB to ~600MB -- not to mention the ...
jackxujh's user avatar
  • 680
3 votes
2 answers
2k views

compress Long size file into multiple limited size xz file

I have files of 28GB size. I want to compress using .xz LZMA, with .xz chuncks of 1G (1024MB) size files... MyFile.vdi -> MyFile00.xz, MyFile01.xz, MyFile02.xz... How do it in macOS? EDIT sh-3....
Chepe Questn's user avatar
1 vote
1 answer
119 views

Breaking pdf to various images, compress, and recombine

I want to save each page of a PDF file as separate image, compress them, and recombine back as PDF. Some PDF files I often use are strangely large in size. I mean, some 100 pages but some 200M. I ...
Violapterin's user avatar
4 votes
1 answer
6k views

Compress jpeg images from Terminal [duplicate]

I am looking for a way to compress jpeg images on a Mac from Terminal. Basically, a library like pngquant, except it is for jpeg format. Are you aware of a software that does that?
sanjihan's user avatar
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1 vote
0 answers
50 views

What are those "._<filename>" files show in tar verbose output, but are not in the untarred directory? [duplicate]

Some hidden files appear in the verbose output of tar, but then do not exist in the directory where the tar output is deposited. I am surprised by this because I thought working in Terminal command ...
riverflows's user avatar
4 votes
2 answers
7k views

How to compress iPhone QuickTime screen recording's file size?

I've recorded my iPhone screen through QuickTime on my MacBook and made several recordings already. Unfortunately, the resulting files are too large. They get saved in .MOV format, and 10 mins takes ...
RDJ's user avatar
  • 41
15 votes
1 answer
7k views

Can I turn off swap and/or memory compression on macOS 10.12, Sierra?

Is there a way with macOS 10.12, Sierra, to safely turn off compressed memory? And is there a way to turn off safely swap? This was possible on macOS 10.9 and macOS 10.10. Although it sometimes ...
dszakal's user avatar
  • 544
4 votes
1 answer
9k views

Create tar archive with xz compression?

I'd like to create a tarball using the xz compression tool. According to google, as of 10.10 there is an undocumented "--xz" switch for tar but I can't get it to work. On linux there is a "-J" switch ...
Chuck Remes's user avatar
4 votes
4 answers
6k views

How to extract an .ace compressed file?

Is there a way to open .ace compressed file on macOS? I tried searching for solutions but haven't come across any method to extract it yet.
Jash Jacob's user avatar
  • 4,461
4 votes
1 answer
1k views

Multithreaded compression in xz on macos

Is it possible to use the multithreaded compression built into xz 5.2+ on macos? Currently using homebrew xz 5.2.3 on macos 10.12.3 with a hyperthreaded quadcore cpu and no matter my setting for ...
xref's user avatar
  • 215
1 vote
2 answers
633 views

Compress multiple files in different folders

Could someone help me with compressing thousands of files? I have a lot of folders and a lot of files in these folders, i would like to know if it's possible to compress each file separately. Foe ...
user218350's user avatar
1 vote
1 answer
54 views

How can I de-compress a source file on my basic MacBookAir (macOS Sierra Version 10.12.2)

I've downloaded the source file from https://arxiv.org/format/1610.01410v2 How can I decompress it to obtain the plain text (say, in a TextEdit file)? The file I downloaded is designated 1610....
Paul B. Slater's user avatar
2 votes
3 answers
2k views

Terminal - Is the built in zip command lossy?

I'm using BASH in the terminal on Yosemite. Is the zip command lossy? I'm using it like this zip -er ./output.zip ./input -e encrypt -r recurse I am trying to avoid lossy compression when ...
Kellen Stuart's user avatar
1 vote
1 answer
374 views

Preferred sources/methods for VirtualBox images on macOS 10.12?

I have a 2016 MacBook Pro running macOS 10.12 and I want to run a Linux VM such as Mint using VirtualBox. I am looking for best practices or official/recommended sources for an image that is packaged ...
JeremyDouglass's user avatar
3 votes
1 answer
6k views

Why does .tar.gz automatically extract the GZip archive when I download it in Safari?

I downloaded a .tar.gz archive backup of a website. Every time I download it, when I click the magnifying glass in Safari Downloads, it takes me to the file, but it's now just a .tar, and so is ...
Lachlan Macnish's user avatar
0 votes
1 answer
119 views

How is the Compressed Mem column in Activity Monitor calculated?

Say we have something like Process Name Memory Compressed Mem Firefox 2.60 GB 1 GB What do the figures mean? Is it: 1GB is compressed and we don't know how much it's compressed by so ...
nevster's user avatar
  • 974
2 votes
1 answer
798 views

Do Apple Lossless tracks remain lossless when sent via Airplay to a 4th gen Apple TV?

This question, from 2012, asks whether there is loss in the signal quality of an Apple-Lossless-encoded file when transmitted from a Macbook to an Airport Express. I am wondering whether things are ...
Calaf's user avatar
  • 4,379
6 votes
2 answers
1k views

Will Time Machine store the same data twice in this situation?

I had 80 GB of movies on my internal HDD. Time Machine backed them up to an external HDD, along with everything else on my drive. I then moved those movies to another external HDD (which is not being ...
Fiksdal's user avatar
  • 672
1 vote
1 answer
4k views

List number of files in multiple zip files

How can I get the total number of files in multiple zip files at the same time? I have around 1000 zipfiles in one folder and would like to know the total amount of files inside them all combined. How ...
Halalbin's user avatar