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deus-libri
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C++2020–2022
deus-libri / preflate

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deflate stream reconstruction library

Libraries & SDKs
Explore on GitHubRead Hacker News discussions
2Distinct people
3Mentions
0Explicit recommenders
41GitHub stars
REPOSITORY AT A GLANCE

What to know before exploring

What it is

deflate stream reconstruction library

GitHub

Where it is used

No documented product use has been verified yet.

What people are saying

No recommendation phrase was found in the indexed comments.

No classified warning is attached to this page. Read the discussions before treating silence as approval.

Also in these discussions

No other repository is repeatedly linked in the same discussions.

This week on Hacker News

Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 3:03:16 PM UTC.

No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.

Mentions over time

HN mentions by month3 dated mentions

Observed mentions: 2020-10-31 22:58:56 UTC to 2022-09-10 11:57:22 UTC.

012020-10-01 00:00:00 UTC to 2020-11-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 commentsOct 20202020-11-01 00:00:00 UTC to 2020-12-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2020-12-01 00:00:00 UTC to 2021-01-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2021-01-01 00:00:00 UTC to 2021-02-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2021-02-01 00:00:00 UTC to 2021-03-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2021-03-01 00:00:00 UTC to 2021-04-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2021-04-01 00:00:00 UTC to 2021-05-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2021-05-01 00:00:00 UTC to 2021-06-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2021-06-01 00:00:00 UTC to 2021-07-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2021-07-01 00:00:00 UTC to 2021-08-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2021-08-01 00:00:00 UTC to 2021-09-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2021-09-01 00:00:00 UTC to 2021-10-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 commentsSep 20212021-10-01 00:00:00 UTC to 2021-11-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2021-11-01 00:00:00 UTC to 2021-12-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2021-12-01 00:00:00 UTC to 2022-01-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2022-01-01 00:00:00 UTC to 2022-02-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2022-02-01 00:00:00 UTC to 2022-03-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2022-03-01 00:00:00 UTC to 2022-04-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2022-04-01 00:00:00 UTC to 2022-05-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2022-05-01 00:00:00 UTC to 2022-06-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2022-06-01 00:00:00 UTC to 2022-07-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2022-07-01 00:00:00 UTC to 2022-08-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2022-08-01 00:00:00 UTC to 2022-09-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 comments2022-09-01 00:00:00 UTC to 2022-10-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 commentsSep 2022

Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.

View mention counts and date ranges
UTC ranges include their start and exclude their end. Select a period to filter the source evidence.
PeriodStart (UTC)End (exclusive, UTC)MentionsSubmissionsComments
Oct 20202020-10-01 00:00:00 UTC2020-11-01 00:00:00 UTC101
Nov 20202020-11-01 00:00:00 UTC2020-12-01 00:00:00 UTC000
Dec 20202020-12-01 00:00:00 UTC2021-01-01 00:00:00 UTC000
Jan 20212021-01-01 00:00:00 UTC2021-02-01 00:00:00 UTC000
Feb 20212021-02-01 00:00:00 UTC2021-03-01 00:00:00 UTC000
Mar 20212021-03-01 00:00:00 UTC2021-04-01 00:00:00 UTC000
Apr 20212021-04-01 00:00:00 UTC2021-05-01 00:00:00 UTC000
May 20212021-05-01 00:00:00 UTC2021-06-01 00:00:00 UTC000
Jun 20212021-06-01 00:00:00 UTC2021-07-01 00:00:00 UTC000
Jul 20212021-07-01 00:00:00 UTC2021-08-01 00:00:00 UTC000
Aug 20212021-08-01 00:00:00 UTC2021-09-01 00:00:00 UTC000
Sep 20212021-09-01 00:00:00 UTC2021-10-01 00:00:00 UTC000
Oct 20212021-10-01 00:00:00 UTC2021-11-01 00:00:00 UTC000
Nov 20212021-11-01 00:00:00 UTC2021-12-01 00:00:00 UTC000
Dec 20212021-12-01 00:00:00 UTC2022-01-01 00:00:00 UTC000
Jan 20222022-01-01 00:00:00 UTC2022-02-01 00:00:00 UTC000
Feb 20222022-02-01 00:00:00 UTC2022-03-01 00:00:00 UTC000
Mar 20222022-03-01 00:00:00 UTC2022-04-01 00:00:00 UTC000
Apr 20222022-04-01 00:00:00 UTC2022-05-01 00:00:00 UTC000
May 20222022-05-01 00:00:00 UTC2022-06-01 00:00:00 UTC000
Jun 20222022-06-01 00:00:00 UTC2022-07-01 00:00:00 UTC000
Jul 20222022-07-01 00:00:00 UTC2022-08-01 00:00:00 UTC000
Aug 20222022-08-01 00:00:00 UTC2022-09-01 00:00:00 UTC101
Sep 20222022-09-01 00:00:00 UTC2022-10-01 00:00:00 UTC101

What Hacker News says

3 sources
lifthrasiir·Sep 10, 2022
It is actually possible to estimate the compression level without actually compressing everything again, because different levels use different strategies which can be identified in some cases. zlib in particular has three strategies [1] and preflate [2] leverages this to store the deflate stream reconstruction data without much bits. [1] https://github.com/madler/zlib/blob/21767c6/deflate.c#L134-L... [2] https://github.com/deus-libri/preflate/blob/master/preflate_...
In Gzip and Brotli Compression Level Estimator
scottlamb·Oct 31, 2020
Looks like it uses the preflate library [1] which back-references precomp in its README: > "precomp" is a tool which used to be able to do the bit-correct reconstruction very efficiently, but only for deflate streams that were created by the ZLIB library. (It only needed to store the three relevant ZLIB parameters to allow reconstruction.) It bailed out for anything created by 7zip, kzip, or similar tools. Of course, "precomp" also handles JPG, PNG, ZIP, GIF, PDF, MP3, etc, which makes a very nice tool, and it is open source. UPDATE The latest development version of "precomp" incorporates the "preflate" library. so precomp used to work as you describe: it depended on having exactly the same zlib algorithm as the one that produced the original data. Now it uses preflate, which has some hybrid approach: > for deflate streams created by ZLIB
Read the rest
at any compression level, we want to be able to reconstruct it with only a few bytes of reconstruction information (like "precomp") > for all other deflate streams, we want to be able to reconstruct them with reconstruction information that is not much larger than "reflate" > "reflate" can reconstruct any deflate stream (also 7zip, kzip, etc), but it is only close to perfect for streams that were created by ZLIB, compression level 9. All lower compression levels of ZLIB require increasing reconstruction info, the further from level 9, the bigger the required reconstruction data. "reflate" only handles deflate streams, and is not open source. As far as I know, it is also part of PowerArchiver. I'd be curious to learn a little more about the "reconstruction information" but I don't see a write-up. So far I'm not quite curious enough to dig through preflate's source code. [1] https://github.com/deus-libri/preflate
In Precomp: Further compress files that are already compressed

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