2007-06-18, 03:38 | Link #2 |
I see what you did there!
Scanlator
|
Cycle Redundancy Check.
It's basically a throw-back to pre-2003 fansubs. Before BitTorrent, we had no way of know whether or not a download completed successfully and without corruption. CRC is nothing more than a hex value assigned to any given file. If your file's CRC doesn't match the CRC on the label, your download is corrupted or incomplete. You can calculate it using programs like HashCalc and QuickSFV (not sure what other people use).
__________________
|
2007-06-18, 03:49 | Link #3 |
Just call me Ojisan
Join Date: Jan 2003
Location: U.K. Hampshire
|
Cyclic Redundancy Check actually (in case you want to search on somewhere like Wiki, Cyclic Redundancy Check)
|
2007-06-18, 07:00 | Link #6 |
Aegisub dev
Join Date: Sep 2004
Location: Stockholm, Sweden
Age: 39
|
CRC tagging is useful in a few cases still:
Those people who stash CD's/DVD's with fansubs, it's not uncommon for optical media to "lose data" over time. With a CRC tag (or SFV file - that's basically just a list of filenames and the expected CRC for them) you can at least check whether the files are still intact. Then there's the case of private sharing parties or such. Sometimes you can also get corruption when copying over a network using a non-verifying protocol. And of course just the case of other disks going bad.
__________________
|
2007-06-19, 18:19 | Link #9 |
Retired
Fansubber
Join Date: Aug 2004
|
Just to elaborate, yes, it's good for IRC fserv and xdcc transfers to check if the download had completed in the first place or if the original file is complete in the first place if the file is somehow corrupt. Especially for fservs if the filesizes are not readily available. Filesize referencing is a little easier with xdcc.
|
2007-06-19, 21:18 | Link #11 |
Away for good
Join Date: Mar 2006
Age: 35
|
The CRC or MD5 (that a very low populate use) can also be used as I've seen, to search for a specific episode or file. This was used in pre 2004, With like DC++ or an other client.
But as emptyeighty said earlier, the rar madness nearly destroyed that ideal for both file checking (mainly for avi/divx [container]) and searching. |
2007-06-21, 14:36 | Link #13 |
A2000A
Fansubber
|
And putting it in the filename tag saves you the trouble of storing checksum information in a separate file.
If I want to check a series, it's as simple as selecting the heap of files, generating CRCs for them, and glancing over the output .sfv file to check if it all matches up. I suppose you could use the torrents to check, but files travel around after initial download. I'll second Starks on suggesting QuickSFV btw, it's straightforward and simple. (And MD5 is still more common than the hashes you find on Share and the like, hehe...) |
2007-06-21, 20:10 | Link #15 | |
Join Date: Feb 2006
|
Quote:
|
|
2007-06-27, 21:38 | Link #16 | |
Away for good
Join Date: Mar 2006
Age: 35
|
Quote:
There's 2 types of tagging systems which are currently being used... Well I'll leave that aside, before anything happens. |
|
2007-07-05, 06:46 | Link #18 | |
makes no files now
Join Date: May 2006
|
/me imagines what it would be like to put the never-ending-long MD5 hash into a filename string
It's apparently slower than CRC... Not sure about the rest, but it definitely would be a silly idea to put that into a filename. And also, I'll quote Nicholi; Quote:
__________________
|
|
2007-07-05, 06:54 | Link #19 |
eyewitness
Join Date: Jan 2007
|
On my HD all files are renamed to a shorter form and accompanied by a md5sum file. But you can't include it so nicely in the filename. Or better said, you don't want to.
To detect random corruptions CRC is good enough. MD5 has the advantage that it is much harder to fake by an intelligent attacker but that does only matter if you're paranoid, resposible for preventing industrial sabotage in your company, or have a computer savvy little brother who might be planning to replace your hentai collection by Pokemon episodes while retaining the checksum. Oh, and md5 is not slower. Reading the file from HD is the by far most time consuming process.
__________________
|
2007-07-05, 07:13 | Link #20 | |
Senior Member
Join Date: Jan 2006
|
Quote:
|
|
|
|