Talk:Parchive

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Merge with PAR File[edit]

I vote yes merge them. I'm willing to do it, they're both small. Have PAR/PAR2 files redirect tho so we don't get dupes again. -- RevRagnarok 02:03, 15 May 2006 (UTC)[reply]

Beat ya to the merge. ;) Cwolfsheep 20:09, 3 June 2006 (UTC)[reply]
Cool, I was just looking it over, kudos! -- RevRagnarok Talk Contrib Reverts 16:23, 4 June 2006 (UTC)[reply]
Regarding the discussion above, it seems that a merge between Parchive and Par file previously took place, and the proposed merge of Parchive and Parity file is actually a recurrence of the same situation. Should probably just go ahead with the merge. Ringbang (talk) 20:13, 17 February 2009 (UTC)[reply]
I agree with the merge! • Sbmeirow • Talk • 16:42, 14 September 2013 (UTC)[reply]

Big rewrite[edit]

Please comment. Spent quite some time on it. -- RevRagnarok Talk Contrib Reverts 04:52, 10 June 2006 (UTC)[reply]

Other uses[edit]

Please contribute... I do what I mentioned with CD-R and DVD-R because I have had CD-Rs fade in the sun and get bit errors. The DAR stuff is just an extra precaution. — RevRagnarok Talk Contrib 05:56, 10 June 2006 (UTC)[reply]

Here is my Makefile. It will skip the subdirectory "Processed." I've used it on Linux and Cygwin:
OUT=RevRagnarok.par2
REDUNDANCY=10

.SILENT: all $(OUT)

SUBDIRS = $(shell find . -iwholename './Processed' -prune -o -type d -printf "''%P'Y'" | perl -pe 's/^\x27\x27\x27Y\x27//g;s/ /\\ /g;s/\x27\x27/ /g;s/\x27*Y\s*\x27/\/$(OUT) /g')

.PHONY: subdirs $(SUBDIRS)

HERE = $(shell pwd | perl -pe 's/ /\\ /g')

subdirs: $(SUBDIRS)

$(SUBDIRS):
	@$(MAKE) $(MAKEFLAGS) -C "$(patsubst %/$(OUT),%,$@)" -f $(HERE)/Makefile par2_files

par2_files : $(OUT)

$(OUT) : 
	$(if $(wildcard *.mp3), par2 c -v -r$(REDUNDANCY) $@ *.mp3, )

— RevRagnarok Talk Contrib 03:47, 22 September 2006 (UTC)[reply]

Shouldn't be used for security[edit]

PAR does not use cryptographically secure checksums, and therefore cannot be used to assure edits have not occurred. Cryptographically secure checksumming algorithms such as SHA-1 should be used instead.
-- ArbitraryConstant 20:33, 21 December 2006 (UTC)[reply]

Simplified Layman's terms explanation[edit]

This article needs a simple layman's terms explanation. I wrote the following based on how I understand error correction to work, but I'm far from an expert. So I'm gonna post my proposed article text here and let someone else post it once an expert confirms the validity.

Error correction works sort of like a game of sudoku. If a single number is missing from any random location on nearly complete sudoku board, then any one of the relational number rules of sudoku provide all the extra information you need to correctly fill in that particular missing number box back to its intended value. However, as more and more numbers are missing you need to know more and more different sudoku rules in order to recreate the missing numbers.

So the original data to be kept corrected of errors is like the numbers you start with on an incomplete sudoku board, and the additional error correction parity files you use to correct errors in your data back to the original set are like the rules you use on a sudoku board to fill in the missing number squares back to their intended values.

If too many squares on your sudoku board are missing (i.e. there are too many errors in your data) then the rules of sudoku don't give you enough information to fill in the missing numbers (i.e. the parity files don't contain enough extra information to recreate the errors in your data). But if you knew additional sudoku rules (i.e. had more parity files) then you could recreate the correct set of numbers on your sudoku board (i.e. you could recreate the correct data in the portions which contain errors).

---

If that is approximately correct, then please add this text to the article! =) —Preceding unsigned comment added by 67.101.31.49 (talk) 08:41, 19 September 2007 (UTC)[reply]

Yeah, that explanation kind of works. ;) However, sudoku computations are likely a little more complicated to compute what is missing and you also know a priori what data is corrupted/missing so the analogy isn't close enough to go into the article (IMHO). It's more like picking up a "completed" game out of the trash and seeing two 8s in a single row and saying, "Well, I know that isn't right..." and then fixing it. — RevRagnarok Talk Contrib 23:39, 27 September 2007 (UTC)[reply]

---

I don't believe this article needs a "simple layman's terms". It should say that Reed-Solomon encoding is used and then forward people to the Reed-Solomon page. The "simple layman's terms" should go on the Reed-Solomon page.

Also, the Sudoku analogy is poor. It is best described using a set of integers. The first redundant block is the sum of all the integers. If any one integer is missing, the missing value is equal to the sum minus all the present values. The second redundant block is equal to the sum of the squares of all the integers. If two values, X and Y are missing, you can use the sums to find out X + Y and X^2 + Y^2 and given two equations with two unknowns, you can solve for X and Y. The third redundant block is the sum of all the cubes, the fourth redundant block is the sum of all the integers to the fourth power, etc. The equations get more complicated, but their all solvable.

Reed-Solomon encoding is just that. The only difference is that it is done using a different "addition" and "multiplication" operation. Adding two 32-bit unsigned integers can generate a 33-bit value. And multiplying two 32-bit unsigned integers can generate a 64-bit value. The addition and multiplication used in Reed-Solomon are on a Galois Field and have the special property that adding or multiplying two 32-bit values always generates a 32-bit value.

Anyway, this "layman's terms" description should go on the Reed-Solomon page. Par1 is Reed-Solomon but the Par2 file format is flexible enough to support other error correcting codes, such as Tornado Codes, LT Codes, or Online Codes.

- Michael Nahas (designer of the Par2 file format). —Preceding unsigned comment added by Mdnahas (talk • contribs) 23:12, 13 May 2008 (UTC)[reply]

Unicode[edit]

This revision asked about Unicode. I didn't read the forum post, but I will assume they mean for the file names and other metadata where plain text is stored. I am sure that the payload can be anything. — RevRagnarok Talk Contrib 02:38, 5 March 2010 (UTC)[reply]

Predecessors[edit]

So what was used on Usenet for ECCing stuff on the bin hierarchy before par? The mentioned methods are just methods of serializing, not ECCing. --Gwern (contribs) 19:20 8 March 2010 (GMT)

Dubious[edit]

NNTP was not designed to be a reliable transmission medium.

At least viewed from the transport layer protocol NNTP is transported with (TCP), NNTP should be considered a reliable transmission medium. --Abdull (talk) 23:48, 19 August 2010 (UTC)[reply]

... yes, but just because the individual packets are guaranteed to go where they need, does not change the fact that NNTP servers are allowed to filter and cherry-pick, and that all "parts" of a binary posting will not necessarily exist or be available to the end user. 75.147.198.171 (talk) 22:57, 5 April 2011 (UTC)[reply]

Michael Nahas[edit]

I'm Michael Nahas, so I shouldn't edit this page. But I'm pretty sure I'm allowed to comment on it.

1) I don't remember names like Howard Fukada (spelled correctly?) but there were many clamoring for a new version of par with bug fixes and expanded features. That name should include a citation, because it certainly isn't in the file spec. 2) I organized the ideas for Par2 into a specification. I don't remember Peter being more vocal than any others in his generation of ideas. (It may have been that I trusted people who had already written Par1 clients more than Peter...) 3) Peter _was_ instrumental in writing the first Par2 client, QuickPar. His experience resulted in changes to the spec, so that the one dated May 11th 2003 had "(Final Draft)" in the title. I don't think any of us involved would have said the draft was final until we had working code. 4) Par2 DOES have support for Unicode. It is _optional_ and few (no?) clients support it. 5) I diagnosed the bug in Par1 which lead to the publishing of the errata. I made changes to the algorithm in Par2 in order to fix the bug. My changes were NOT SUFFICIENT. The bug is encountered less often, but it still exists in Par2. Removing this bug is one driving force for a new version of Par (either 2.1 or Par3). 6) There is no Par3. There is a person who keeps trying to do something ... badly. For example, Par2 DOES already has support for directories and has optional support for Unicode. 7) (Good) reasons for Par3 include (a) fixing the bug, (b) new algorithms that are faster than Reed-Solomon (see Tornado Codes, LT Codes, Online Codes, etc.) (c) manditory support for Unicode (probably via UTF-8), and maybe (d) supporting disk images like DVDisaster does.

Otherwise, the page seems great. Kinda cool to have something I had a part in on Wikipedia.

Michael Nahas — Preceding unsigned comment added by Mdnahas (talk • contribs) 19:49, 2 July 2011 (UTC)[reply]

Merger proposal[edit]

I added a merge proposal template to Parity file because the only parity files that exist are Parchive files. If I'm wrong about that, sound off. Otherwise, that article should probably go into a section here that discusses the technical features of Parchive formats. Badon (talk) 21:58, 3 September 2012 (UTC)[reply]

I agree with the merge! • Sbmeirow • Talk • 16:43, 14 September 2013 (UTC)[reply]

Pronunciation[edit]

How is parchive pronounced? Most Wikipedia pages have suggested pronunciations but there is none on this page (unless I overlooked it).

I've not used a parchive before (or if I did, long ago) and never had to say the word and I'm not a linguist but I would think it's par-kive. However, p-ar-kive and park-ive could also be used.

And putting in the correct pronunciation symbols is not something I even have time to research.

(Hmm, maybe it should be a contraction: par'chive, but I don't think nouns are contractible.) — Preceding unsigned comment added by PReinie (talk • contribs) 18:52, 5 February 2015 (UTC)[reply]

External links modified[edit]

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External links modified[edit]

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multipar.eu removed[edit]

The original developer now considers that site as unauthorized malicious code, a spam site https://www.livebusinesschat.com/smf/index.php?topic=6108.0 https://www.livebusinesschat.com/smf/index.php?topic=5851.0 — Preceding unsigned comment added by 70.36.223.208 (talk) 17:18, 1 January 2017 (UTC)[reply]

Software: New Multi-Platform Category[edit]

A number of the multi-platform software was listed multiple times under the various OSes, and some others weren't. I've split these off into its own category to avoid duplicate mentions (each with their own, slightly different description text) and make it clear that it's multi-platform (as opposed to only being supported on Windows and Linux, for example).

Hopefully this makes the listing clearer, more accurate and concise.

SkyBlueGem (talk) 12:30, 24 May 2018 (UTC)[reply]

SRRDB[edit]

SRRDB is a similar standard that can rebuild broken files, and is used in the warez scene.

Family Guy Guy (talk) 10:56, 17 October 2018 (UTC)[reply]

No it doesn't. It only verifies the files, doesn't rebuild broken data files - well, maybe except metadata (SFV, NFO, rar header).
How it works
What is this .srr file? and What happens if I try to rebuild a release and the extracted files are corrupted? MarMi wiki (talk) 15:41, 5 June 2022 (UTC)[reply]
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