Questions tagged [compression]

Compression decreases the size of data.

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Unable to decompress file with gzip

I have a file called myfile.dat.gz that I need to decompress. I have been trying gzip -d myfile.dat.gz, but this results in the error gzip: myfile.dat.gz: invalid compressed data--format violated. ...
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29 views

Extracting LZMA file from firmware binary using dd command

direct link to firmware: https://www.siriusretail.com/SXVCT1/SXVCT1_update_v36.zip I'm struggling to unpack this firmware. Using binwalk binwalk -e SXVCT1_F.027 I can see JPEG image data, TIFF image ...
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40 views

In what order should I use stabilization and compression with ffmpeg?

I shoot videos of soccer games on a Canon Vixia which records at 60fps HD with h264 compression. From the camera it results in 20GB files which I have been recompressing (to save on storage and ...
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How can I reduce the file size of a video encoded with wmv2 in ffmpeg?

I have some videos of a slide presentation with audio and need to put them in a wmv container. These videos are intended to be viewed with Windows Media Player. I initially made the mistake to use the ...
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29 views

btrfs volume in fstab fails to boot with compress-force

in my fstab, the btrfs volume boots with no problem when the option set is compress=zstd:15, however, as soon as i set it to compress-force=zstd:15, it fails to boot because of a failed dependency ...
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How do I open a json file compressed with snappy compression?

A firefox extension has become corrupt which means I can't export my data using the graphical user interface, but I can copy my profile data associated with my extension by copying a folder. The file ...
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30 views

Extract timestamp of I-frames of video using ffmpeg

If I understand correctly, I-frames are the frames that are unaltered during video compression. I want to extract the exact timestamps of these I-frames and save the output in a txt file. How do I do ...
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1answer
67 views

How do i unzip files with 7z and do not replace files that have the same name but different hash?

How can i tell 7z to extract all the files in the directory, tell it to do not replace files that have the same name but different hash? preferably tell it to extract the files and rename them to ...
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56k views

Why are tar.xz files 15x smaller when using Python's tar library compared to macOS tar?

Context I'm compressing ~1.3 GB folders each filled with 1440 JSON files and find that there's a 15-fold difference between using the tar command and Python's built-in tarfile library on macOS or ...
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how do i use fuse to mount a file in a compressed file as a symlink

i have a directory full of .xz files, each containing a single file (not tar). uncompressed, the directory is 23GiB. (*.xml) compressed, the directory is 1GiB. (*.xml.xz) how do i fool the filesystem ...
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105 views

Mac: “tar: Error exit delayed from previous errors.”

I have a website backup that was created in cPanel and I'm trying to uncompress the .tar.gz on my Mac. I'm getting this error: tar: Error exit delayed from previous errors. I tried to use Archive ...
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81 views

Find out which version of which specific program created a (partial) ZIP archive

Is it possible to determine which specific version of which specific program created a given ZIP archive, based on its metadata? And also, is the outcome of a ZIP / RAR compression affected by the ...
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88 views

recompressing .gz and .bz2 files to attain the same hash/checksum (mod timestamps?)

i want to duplicate the entire contents of wikimedia's dumps, monthly, and upload them to amazon glacier and/or tape backup and/or a third backup medium that can survive corporation collapse/...
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85 views

How to recover a bitcoin wallet on a Windows drive amid 30 gigabytes of files

I need to recover a bitcoin wallet that I created about 8 years ago. I was a kid, and I thought I would be super clever and zip or rar the wallet, then change the extension to an image file. I ...
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73 views

Compressing pdfs

I've been using a web service at ilovepdf.com to compress some PDF files. And by some, I mean "several hundred to several thousand". The output files look identical (to my eye) and weigh in ...
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176 views

Uncompress .tar.gz format getting error “tar: Unrecognized archive format”

I've downloaded a ".tr.gz" file with a size of 10 GB from here (after downloading completed, I renamed it and deleted .partb to become dataset cleaned.tar.gz) while I'm trying to uncompress ...
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24 views

RAR command-line: how to include a directory (recursively) but with another name in the archive?

I have read RAR a folder without persisting the full path which helps about the RAR -ep1 switch but I still have the following problem: I want to add the directory D:\Temp\FolderA and its ...
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43 views

Which Folder to File method compresses the most? zip vs tar.gz vs tar.bz2 vs tar

I'm trying to download a large Gitlab repo in a script, and Gitlab offers each of the zip, tar.gz, tar.bz2 and tar options, and I want to pick the one that will have the smallest file size. Will one ...
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1answer
29 views

Creating GPG encrypted tar.gz Backup fails

I hope this kind of question is ok here ;) I am on Debian 10 Buster, trying to create an (GPG) encrypted, compressed tar file without intermediary files. I found this article[1] on the web which ...
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12 views

Optimize time when creating archive

Currently, I am using the following command to create an archive with files older than 7 days: find /var/tunningLog/ -type f -mtime +7 -print0 | tar -czf "/var/tunningLog/$(date '+%Y-%m-%d').tar....
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107 views

7z: Multithreaded Decompression

What is needed to compress an archive so that it uses multithreading when being decompressed? I have read that that only compression protocol that can use multi-threading to decompress an archive is ...
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1answer
97 views

Compress all files to the “9” level with gimp

I created the scripts from Using Gimp to batch convert images to another format in Windows tip made by @forrest-voight. Can anyone tell me how I can add options to this script so that the maximum ...
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Scheduled compression of large files and delete

How can I do the following? scan a folder (including sub-folder) for large files (e.g. > 30 MB) for positive results, compress at original location (while not keeping the uncompressed file) on ...
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1answer
29 views

Compress PDF of images without downsampling

How can I compress a 300 DPI PDF of images without downsampling? e.g. without using gs or alternative to convert it into a 150 DPI PDF? I'm looking for something like https://docupub.com/pdfcompress/ ...
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NTFS Folder Compression Fades

I am on a Windows Server with limited disk capacity. I used windows build in compression of folders to compress a 30 Gbyte file to 22 GByte. I noticed that while running a programm which frequently ...
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1answer
33 views

Best way to clean up over-compressed audio with a clean sample in Audacity?

I have an audio file, which sounds a little muffled due to compression (it's not very bad however). I want to clean it up as much as possible with Audacity or similar (free) software. I have a high ...
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1answer
93 views

FFmpeg HEVC compression?

I'm part way through a video processing program and am using ffmpeg to read a frame, process it and then write it to an output file. Input files are HEVC codec and are currently being read and then ...
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1answer
59 views

Why do I see strange characters when using “cat” on a zlib compressed file?

When I try to run the cat command on a zlib compressed file, I get this sequence of strange characters xK??OR04d?H????/?I;{<% Where they come from?
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33 views

WinRar is acting weirdly

I tried to unarchive a 40 gig zip archive in my d drive which at the time had 120 gigs free but i was greated by a message that i don't have enough disk space i was really confused and i decided to ...
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does handbrake not reduce video quality while compressing videos?

I was just looking for several ways to compress videos, and I found some saying that we can compress videos with handbrake without loss in quality. As far I know compressions there are always quality-...
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100 views

How to compress an image as much as possible?

I have an image with a size of 1x1. (.png) It's a black pixel. I used Photoshop to create it as a Bitmap and when I saved it, it turned out 1.2kB+. This was not very surprising, I thought Photoshop ...
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56 views

Why are ffmpeg processed videos per default multiple times smaller in file size than the input file?

I have a mp4 movie of 1:15min length, made with the Sony Alpha 6400 4k camera. It has a size of 528MB. I want to cut it using ffmpeg. Although I only cut a few seconds, the new video was much smaller. ...
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32 views

Ffmpeg decompress xz/gz/zip in memory

I have a xz compressed y4m raw video file (sintel-4k.y4m.xz) and I would like to transcode it using ffmpeg, decompressing in memory. I do not have enough disk space to decompress the file to disc and ...
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261 views

How to properly compress BTRFS subvolumes NOT compressed before?

Background I maintain multiple Synology NAS of different models and those support so called shared folders. If the volume containing those folders is formatted using BTRFS, which is the case for me, ...
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32 views

How to compress one folder into multiple .zip, all independently extractible?

I work with some big image datasets containing millions of images, and I often need to compress the results of each step of processing to be uploaded as backup. I have seen that some datasets can be ...
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What are good OBS settings for recording still screen (lecture) with mouse cursor in low size and good quality?

How could I reproduce these settings with OBS ffmpeg recorder? Format : MPEG-4 Format profile : Base Media / Version 2 Codec ID : mp42 (isom/mp42) Format : AVC Format profile : High@L5.1 Format ...
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How to change password of multiple ZIP archive files at once?

I have 50 password protected ZIP compressed archive files. By design, all the files have the same password. I now want to change the password for all those ZIP files to a different password (again, ...
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1answer
46 views

Compressing an MTS file to MP4 gives error in QuickTime

I have a long video file that I want to trim, resize, and compress with H264: ffmpeg -y -ss 1.2 -to 2:03.800 -i long.MTS -vcodec libx264 -vf scale=320:-1 -vb 500k short.mp4 The file plays in VLC and ...
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230 views

Auto-Transcode/Compress .mkv to .mp4 on Qnap TS-251+

I rip my DVDs with MakeMKV in order to be able to watch them on my TV, as I do not have a DVD-player that supports any output connector that fit into my TV as the TV is relatively new whereas the DVD-...
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1answer
207 views

How can I count the number of files inside a tar.gz file (don't want to decompress)

I have a tar.gz file (neatly 1TB size). I want to count the number of files inside this tar.gz file. I used the following command tar -tzf file.tar.gz but it only lists the file name while I need the ...
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34 views

How to encrypt whole folders in Aes crypt?

Apparantely we cannot Encrypt whole directories(folders) using Aes Crypt. Is there any way to do it? Currently I need to first compress it into archives like zip or rar, but thats very time-consuming ...
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449 views

WIM file compression

I build a custom windows 10 installer via sysprep (windows 10 pro Build 20H2). The windows created WIM-file is too large to my liking, over 9gb (want it to fit on a 8gb drive). Therefor I was trying ...
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180 views

“Windows Sandbox failed to start, virtual hard disk files must be uncompressed and unencrypted”

I have Windows 10 Pro and I successfully installed Windows Sandbox. However, when I try to run it, it shows the following error: My (physical) hard drive is indeed compressed (NTFS compression) and ...
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1answer
53 views

Piping Unrar Output to FFMPEG

I have a password protected .rar file. It's large, so using unrar e large.rar is time consuming. Once extracted, the file will be large.avi Then I have to do ffmpeg -i large.avi large.mp4 I was hoping ...
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8 views

crc mismatch at the end but the extractor does'nt show the corrupted part

i have a big file, more than 150 gigabytes. its about 70 parts of 2 gigabyte *.rar files. when i extract them, winrar or 7-zip does'nt show any corrupted file but at the end, it shows crc mismatch. ...
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18 views

Extract zip files and recompress them into 7zip files [duplicate]

I'd like my zip files to be extracted, then recompressed into 7zip files. Example: Before: $ ls 001.zip 002.zip 003.zip --snip-- 997.zip 998.zip 999.zip After: $ ls 001.7z 002.7z 003.7z --snip-- 997....
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28 views

How to re-encode or compress a v4l2 virtual video device to another virtual device?

what I'm trying to do is to compress video from my webcam so that it's accessible from another v4l2 virtual device (or an alternative medium if necessary) with a bitrate around 2000kbps. Currently ...
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21 views

hdmi output disable compression

I am using a laptop with Linux on it with usual TV connected via HDMI cable(HDMI to HDMI). What I found is that the resulting video output is compressed, most probably in discrete cosine transform ...
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1answer
20 views

How would I make an executable that contains compressed files, and runs one on execution of the file?

Ok, so imagine you have a self-extracting compressed file with the following contents: x.exe images/y.png sfx/z.wav When a user clicks on the compressed file, it runs x.exe instead of extracting ...
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855 views

How to convert .tar.gz to .tar.xz?

How to convert .tar.gz to .tar.xz? I have a bunch of .tar.gz files that I would like to convert to .tar.xz for a better compression. How to do this efficiently? A command like this would be great: How ...

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