Compression decreases the size of data.

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1answer
18 views

How do .rar utilities manage to decompress a hidden compressed file (which is actually binary content appended to another file)?

After a puzzle in puzzles.SE which involved a hidden file appended to a gif, I have a question regarding appended .rar files. By this question I understand why I can add a .rar file content at the ...
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2answers
30 views

Removing pages from PDF doesn't reduce size

Have a PDF (20MB) with 10 pages. I'd like to cut the PDF in two parts of less than ~12MB (mail sending limit). created part1.pdf with pages 1-5 (6 to 10 removed) created part2.pdf with pages 6-10 ...
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10 views

How to compress ext4 partition with Acronis while backup?

With Acronis, when I set to compress ext4 partition before backup, the result is a raw backup and not compressed. The same process with NTFS or FAT32 partition, results are compressed. Please tell ...
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1answer
20 views

Create Send-To-Compressed(zipped)-folder event shortcut on Windows10

I have a really simple question to which I haven't been able to find the right simple answer to. I'm working a lot with zipped (compressed) folders. I want to improve my workflow. After selecting all ...
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2answers
58 views

Batch compress .avi files with ffmpeg which contain previous date in their name

im trying to manage CCTV footage, and im trying to batch compress them with ffmpeg So far i managed to come up with this command ffmpeg -i "0515 210004.mp4" -b 200000 output.avi But i need to do ...
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35 views
+100

How to compress Tesseract-encoded PDFs while maintaining embedded text from OCR?

I've been experimenting with using Tesseract to OCR my PDFs, and it has been mostly successful, particularly with German Fraktur texts (the old style gothic print), which tools like Adobe Acrobat ...
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1answer
21 views

Jpeg File Zipping does not compress at all

i'm trying to compress some jpeg photos, the total dimension is around 150MB, but when i try to zip it using the maximum compressing rate, i keep getting something around 150MB. I tried with Winrar ...
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0answers
15 views

Convert a file from PNG to TIFF restoring TIFF Data

I have a software, that extracts TIFF data from a file and convert this file to PNG (TIFF has a default header with some bytes to be replaced on(width, height, stripbytecounts), so i replace those ...
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2answers
39 views

pg_restore fails on zlib compressed dump

Created a dump of a postgresql (windows version 9.3 or 9.4) database with the command: C:\>pg_dump -U user -Z 6 database > db.dump restoring it with psql or pg_restore fails: ...
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1answer
662 views

System and Compressed Memory: High Disk Usage

System and Compressed Memory is something I had for a long time Ever since I got this new computer, when starting up my computer, System and Compressed Memory (ntoskml.exe) has been using very high ...
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2answers
29 views

Can 7-Zip store the final archive to a custom path on a different partition?

I have a folder "D:/Tutorials/Exercise files" I want to compress "Exercise files" folder and put it on E:/Tutorials/ folder, that is on drive E: automatically from within the 7-zip program. Does ...
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1answer
29 views

Is there a way to toggle the Windows “compress this drive” command through a command prompt?

My friends laptop (a 64-bit Windows 7 Home Premium with 4GB RAM) was running slowly and she asked me to take a look at it. One of the things (besides that the disks had not been defragmented for a ...
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4answers
35 views

how to verify whether a compressed .gz is corrupted or not?

I have many gz downloaded from the internet, and I would like to make sure they are not corrupted. Does the fact that I can open the archive with winzip on windows proves that everything is fine? I ...
0
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1answer
24 views

Recompressing zip - integrity check

I have multiple large zip files and I would like to recompress them without unpacking them (I run the risk of running out of disk space). I am thinking of using advzip for that task. However, I want ...
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1answer
78 views

OpenVPN Bad LZO decompression header byte: 69

On Arch Linux I run OpenVPN 2.3.9 server and I get this error "Bad LZO decompression header byte: 69" I run the client on a rooted Motorola XT1039 android lollipop 5.1 and I use official "OpenVPN ...
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0answers
8 views

How to save as a Video-TS-BUP using DVDShrink

Using DVD Shrink 3.2 I compressed a video that had been converted from MP4 using ConverXtoDVD, however after it was compressed it appeared in my G drive in a format that would not play rather -by ...
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20 views

How does motion estimation work?

I am trying to understand the basics of video compression. I have found many resources addressing this particular subject, but somehow, I haven't clarified it yet on my mind. How does motion ...
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1answer
2k views

Disabling “System and compressed memory” (ntoskrnl.exe)

I am very exhausted by this. This program is destroying my computer. I have an ASUS G750 series laptop, which has 16gbs of RAM and a haswell i7 inside it. It is just a year old. I upgraded from ...
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2answers
306 views

High compressed memory usage in Windows 10

I've been having problems on Windows 10: periodically I get a "low memory" warning. A lot of the Super User questions on this topic talk about driver memory leaks, but as I'll explain below mine ...
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1answer
15 views

How can I get dictionary size of 7z archive using comand line?

I've got an 7z archive, I've read manuals but couldn't find how can I get dictionary size of this archive using comandline?
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1answer
62 views

Creating a ZIP file that extracts cross platform

I need to distribute a large (6GB+) file cross-platform. For practical reasons, I want to zip it down to 2GB+. I originally used Mac OS 10.11 to create the zip file using the Archive Utility. It ...
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4answers
65 views

How can I compress a large file on an already-full disk? [closed]

I have a full disk containing a large file that I want to compress to free up space. Most compression programs require me to have enough free space on the disk to store the compressed file alongside ...
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2answers
74 views

Measure ram usage in Windows 10

I'm currently writing a report of an application and I want to know its memory usage. Windows 10 has a nice feature that compresses memory that is not in process working sets in order to manage more ...
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2answers
383 views

Zip all uncompressed file in a folder in one line

I have a lot of text files that I want to compress. Each file must be compressed separately. But some of them are already compressed. How do I, in one line, compress all files that end with .txt by ...
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2answers
66 views

Use ISO instead of ZIP or RAR to store files?

I have been doing some backups of my old files and lately I was wondering if there is another method of storing and compressing files other than ZIP or RAR. In my case, I want to store various group ...
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1answer
31 views

What are the disadvantages of using ultra compression?

7zip offers an option for ultra compression but I'm guessing that it has some disadvantages (other than being more time consuming) or else it would have been the default option... So what are they?
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1answer
76 views

lossless video using FFmpeg ffv1 on jpeg images is not compressed but expanded

Is it possible for FFmpeg / ffv1.3 / mkv to create a lossless video is not larger than the sum of its parts (and if so, how) and if not, what is a good alternative to come close on size? The video ...
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1answer
42 views

How easy is to recover uncompressed data if one sector is damaged in a 7zip archive?

I have around 100,000 small files which I backup every few weeks. Because they are really small, write speed to my external 2.5" USB 3.0 HDD is really slow. In 7zip, I compressed them using ...
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0answers
21 views

How can throughput be greater than the bandwidth? Is this a valid reason?

I asked this question on networking engineers but it was closed as off topic since it wasn't for professional application. Hope it fits better here. I'm studdying for the CISSP secuirty exam and a ...
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1answer
39 views

Why is plain jar file compressed to 76% but after ProGuard shrink & obfuscate; it is compressed to 102% ?! How to fix?

I have a jar file of size 392 MB. I made another copy of it, so I have now two copies of the same jar file. For one of them I used 7-zip to compress it. It is compressed to 76% of the original size, ...
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1answer
31 views

TAR and compress a directory but skip compression on already compressed files

I want to TAR and compress a user's home directory as efficiently as possible. The problem is there are a lot of large and already compressed (gzip/bzip2) and hard-to compress files (binaries/data) in ...
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2answers
69 views

Why do these PNG images differ so much in size?

I created a lot of tiles and each of my tiles is less than 2 KB except one which is 16.2 KB. It is very similar to another tile I created which is 1.48 KB. Yes, I'm nitpicking about the sizes here but ...
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20 views

How to save compressed (batch processed) video files to the original folders using handbrake?

I use handbrake to compress/encode video files and I'm quite happy with the results. It gives me small file size with no quality loss. The problem is that when I batch convert multiple files from ...
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2answers
35 views

Edit executable file, instead of run, in Compressed Folder Tools

When I open a .zip file in Windows 10, and view it in its Compressed Folder Tools, I can open text files, Windows documents, etc. But for executable text files, like .bat or .js, the open option tries ...
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12 views

7zip File Compression Auto-Selection

When I'm zipping a folder hierarchy, I'd like 7zip to automatically detect whether a file in the folder tree is or is not already compressed, so that it automatically chooses whether to merely add an ...
4
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1answer
27 views

Can compression of folder be undone when it comes to slow?

I know that compressing save disk space on my hard drive and I know that it is mutch slower for read a file. However I will compress the C:\Users folder. Personal files are stored on a SSD drive. ...
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1answer
82 views

Best data compression format available [closed]

I'm sometimes sharing big files (1 GB, Visual Studio C++ Solution) over the internet, but I have very very low upload speed. So, I'm trying to compress my data into the smallest file as possible. I ...
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0answers
50 views

Why is Encase disk image smaller than used space on source HDD?

I am using a forensic disk imaging tool to make an Encase (E01) disk image of a 4TB hard drive. 3.19TB of space is actually used on this disk. The resultant disk image is 2.82TB in size. No ...
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0answers
46 views

Is there anyway to reduce bandwidth usage of Skype for business?

We use a lot of 'Skype for Business' (i.e. the new Microsoft Lync), that I use while consuming expensive roaming data. Was wondering, if there are options (similar to various VLC clients) that lead to ...
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2answers
49 views

Extract .tar.gz file that has files with .gz extension

Using this question I 'zipped' the folder with thousands of images on apache server. This apparently changed the files inside the folder itself and zipped the files. But that's not the issue atm. I ...
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1answer
60 views

Which files and folders are compressed when using compact.exe /CompactOS

I am thinking of using NTFS compression (LZNT1) on my SSD using Windows 7, but I was a little unsure as to which folders would be a good candidate. I was aware that Windows 10 has introduced new ...
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21 views

7zip is creating solid .zip files. Cannot add/remove/overwrite to .zip files ad-hoc

I'm using 7zip as an archive creation tool. .7z files may be created as solid or nonsolid files. .zip files are supposed to be inherently nonsolid. I have ~5GB of hierarchal folder/file structure ...
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0answers
15 views

What is the relationship between dictionary size and compression ratio? [duplicate]

For dictionary based compression algorithms, would there be any real benefit to having a very large dictionary ? In what cases can a large dictionnary be usefull : small or larger files ? Thanks in ...
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41 views

How to extract PPmD archive data in Ubuntu?

So I have a file called ppmdData with no extension, then when I use the file command on it, it says it is a PPMD archive data. When I run 7z x secret, I get an unsupported method error. Can anyone ...
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1answer
57 views

Extract Y-channel of every I-frame from MPEG4 movie as loslessly as possible

I'm working on a video tracking experiment and got stuck with videos that are quite badly compressed with the MPEG4 DivX 5x/6x codec. I'm fairly new to image formats, codecs and compression, but I ...
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1answer
70 views

Extract multipart rar, deleting parts as they are extracted

I have a multipart rar of 80GB unpacked. I have 5GB of free space, and every part of the rar archive is 2GB. What I'm looking for is to extract one part, delete it, extract the next, and so on, as to ...
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1answer
83 views

How to send a delta (differential part) of a large binary file over the Internet?

I have sent a large (>1GB) binary file to a friend over a slow metered data plan and now I need to send the second version of the same file only slightly changed. I want to send only the delta/diff-ed ...
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1answer
52 views

Cut and Compress 4K Video?

I have a 20 second video which size in 4K which size is 125 MB. It is only about a defective electronic component so accuracy is not important. I want it much smaller. I have these options in VLC ...
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0answers
13 views

Strategies To Reduce Compressed File Lookup Time With Pixz?

I have a PIXZ-compressed (level -9) tarball containing around 4000 files (ordered, like pages in a book): compressed size is ~670M. Currently I am programmatically accessing these files using the ...
3
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1answer
33 views

file splitting and compression in pipeline

So I have a massive file something like this... 1/20/2016,somerandomdata 1/20/2016,somerandomdata 1/20/2016,somerandomdata 1/20/2016,somerandomdata 1/21/2016,somerandomdata 1/21/2016,somerandomdata ...