All Questions
Tagged with deflate compression
227
questions
0
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1
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36
views
Time complexity of optimal DEFLATE compression
The DEFLATE algorithm is specified in RFC 1951. However, the encoder can choose freely whether to insert a literal byte, or a sub-match from output buffer for each input byte. Assuming that everything ...
- 21
0
votes
1
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60
views
Deflated file is larger than original and still valid
Inside a zip, I found this deflated file. It's around 1MB, but when inflated (pako.inflateRaw), the original is just 50kb. How is this possible? What happens to the rest of the data when inflated? I'...
- 758
1
vote
1
answer
54
views
How to decompress the contents of a var to another var?
I'm trying to uncompress what's inside of a var into the same var or onto another.
I created a .gz file using gzip -k filename. It generated a filename.gz while keeping the original. I uploaded this ...
- 73
1
vote
1
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78
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Does `deflate` always compress your entire block?
Here's example from the documentation:
byte[] output = new byte[100];
Deflater compresser = new Deflater();
compresser.setInput(input);
compresser.finish();
int compressedDataLength = compresser....
- 1,183
0
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1
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101
views
(Deflate) Is using a code of 284 for a distance pair with a length of 258 allowed in a Huffman compressed Deflate block?
I've been working on a program which aims to optimise deflate compressed files through trying possibly more efficient ways of representing the compressed data, and I recently found a file which uses ...
2
votes
1
answer
148
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Valid gzip file contains a large block of NULL bytes - why?
I have a tar.gz file which contains large blocks of NULL bytes (>1kb). The archive seems to be valid (checked via gzip -t <file-name>) and extraction works properly without issues.
The NULL ...
- 5,632
1
vote
1
answer
48
views
Heuristics to improve brute forcing the location of a DEFLATE block
I work in the data recovery industry. Sometimes a document (.docx) has the beginning overwritten but most of the file might still be intact. A 'docx' is really just a zip file, and the primary ...
- 618
-1
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3
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726
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Compression Gzip/7Zip [closed]
When I calculate the entropy values of files compressed with Gzip, PKZIP, 7ZIP and Winrar, I find that the compression rate of Gzip is higher than the others. The entropy value is higher (indicating ...
- 47
2
votes
1
answer
269
views
how to join (concat) two deflated values without decompression/recompression
I have a lot of text files, i want to compress them to save disk space, then when I need them, concat them and send to a client. To save CPU cycles, I don't want to decompress/recompress data. Also ...
- 33
0
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2
answers
155
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nodejs and vb.net - zlib deflate compression non-compatibility between nodejs and vb
I'm trying to communicate between a client and a server, with the client being on VB.NET and the server on nodejs.
It works, but I'm now trying to use the deflate compression method which seems to not ...
- 1
0
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1
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261
views
Java Deflater for large set of random strings
I am using the Deflater class to try to compress a large set of random strings. My compression and decompression methods look like this:
public static String compressAndEncodeBase64(String text) {
...
- 77
0
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1
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64
views
How to skip detection of random data when attempting to compress?
Do popular compressors such as gzip, 7z, or others using deflate, detect random data strings and skip attempting to compress said strings for sake of speed?
If so, can I switch off this setting?
...
-1
votes
1
answer
350
views
What's wrong with my PNG IDAT CHUNK datas?
i'm trying for learning purpose to create manually a png file from with OpenGL
All other CHUNKS are okk (IHDR, pHY, IEND).
firstly, I read pixels by Opengl :
int s_width = glutGet(GLUT_SCREEN_WIDTH), ...
0
votes
1
answer
326
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PNG IDAT chunk data calculation
I'm trying for learning propose to write my own png file in c language.
I have already read the PNG file format specification and i am now able to write a basic PNG(signature, IHDR CHUNK, 1px-IDAT ...
0
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0
answers
136
views
what wrong with my binary compression with C#
I try to compress some binary string with deflate32 but something is going wrong.
string myString = "101111110101010111111111111";
// convert string to stream
byte[] byteArray = Encoding....
- 1,527