SFV Files Explained in Plain English

SFV files contain CRC32 checksums which can be used to determine whether or not the files listed were downloaded correctly. So, after downloading a set of files, you can use a program like SuperNZB to calculate the CRC32 checksums and then compare them to the checksums in the SFV file. If they match, then everything was downloaded perfectly.

If you open an SFV file with Microsoft Word, or any other word processor that can run scripts, it is possible that a virus in the SFV could get you. When downloading text files, it’s always a good idea to open them with a bare-bones text editor like NotePad on Windows and TextEdit on the Mac, both of which come free with your computer.

Here is a sample SFV file:

------------ Begin Sample SFV File Listing ------------
;15000000  08:52.45 2005-07-28 Some.File.avi.part01.rar
;15000000  08:53.06 2005-07-28 Some.File.avi.part02.rar
;15000000  08:53.28 2005-07-28 Some.File.avi.part03.rar
;15000000  08:53.49 2005-07-28 Some.File.avi.part04.rar
;15000000  08:54.12 2005-07-28 Some.File.avi.part05.rar
;15000000  08:54.35 2005-07-28 Some.File.avi.part06.rar
;15000000  08:54.57 2005-07-28 Some.File.avi.part07.rar
;15000000  08:55.19 2005-07-28 Some.File.avi.part08.rar
;15000000  08:55.40 2005-07-28 Some.File.avi.part09.rar
;15000000  08:56.01 2005-07-28 Some.File.avi.part10.rar
;15000000  08:56.23 2005-07-28 Some.File.avi.part11.rar
;15000000  08:56.44 2005-07-28 Some.File.avi.part12.rar
; 2432113  08:56.48 2005-07-28 Some.File.avi.part13.rar
;   13376  08:59.32 2005-07-28 Some.File.avi.par2
;  397444  08:59.32 2005-07-28 Some.File.avi.vol00+01.PAR2
;  794812  08:59.32 2005-07-28 Some.File.avi.vol01+02.PAR2
; 1576248  08:59.32 2005-07-28 Some.File.avi.vol03+04.PAR2
; 3125820  08:59.32 2005-07-28 Some.File.avi.vol07+08.PAR2
; 6211664  08:59.32 2005-07-28 Some.File.avi.vol15+16.PAR2
;11204548  08:59.32 2005-07-28 Some.File.avi.vol31+29.PAR2
;15442596  08:59.32 2005-07-28 Some.File.avi.vol60+40.PAR2
Some.File.avi.part01.rar 5079A617
Some.File.avi.part02.rar 27001333
Some.File.avi.part03.rar C3B6525B
Some.File.avi.part04.rar B8C8C580
Some.File.avi.part05.rar EAFB98CB
Some.File.avi.part06.rar DB963752
Some.File.avi.part07.rar EC26E01A
Some.File.avi.part08.rar 837AE97F
Some.File.avi.part09.rar E580FB75
Some.File.avi.part10.rar 838EFC3C
Some.File.avi.part11.rar A45455D5
Some.File.avi.part12.rar FF34484F
Some.File.avi.part13.rar B963FE25
Some.File.avi.par2 61443265
Some.File.avi.vol00+01.PAR2 25FD04F2
Some.File.avi.vol01+02.PAR2 2C354FD1
Some.File.avi.vol03+04.PAR2 4FDE31A3
Some.File.avi.vol07+08.PAR2 1EEFB660
Some.File.avi.vol15+16.PAR2 FB8481AA
Some.File.avi.vol31+29.PAR2 95A49937
Some.File.avi.vol60+40.PAR2 286279AE
------------ End of Sample SFV File Listing ------------

The files shown above are a typical RAR/PAR set. Any lines of the SFV file that begin with a semicolon are comments and can be ignored. So, the first relevant line is: “Some.File.avi.part01.rar 5079A617.”

“Some.File.avi.part01.rar” is the name of the file, and “5079A617″ is the value calculated when the data from the file is run through the CRC32 algorithm. “5079A617″ is calculated on the computer of the person who posted the file. If the copy of “Some.File.avi.part01.rar” that you now have yields a value of “5079A617″ then you have an exact copy.


Once you have SuperNZB installed, just click the “SFV” button on the main window:

(Note: The screenshot above, and the demo video below were made on Windows, however the program looks identical on the Macintosh.)

Here is a 5 minute demo video:


CRC32 can also be used to find duplicate files on your system. DupeNuker keeps a database of CRC32 “fingerprints” so you can quickly tell if a new file is one you already have, or have already seen before.


5 Responses to “SFV Files Explained in Plain English”

  1. sharpie says:

    do you HAVE to do this for every sfv file you get ? i dont really get it… why do you have to do do this?

  2. admin says:

    Sharpie,

    You don’t have to do it. Some people want to make sure that every bit is where it’s supposed to be. It just depends on your preference, and how critical the file is. For example, if you download a podcast, listen to it, and then throw it away, it’s not very critical if a few bits got flipped while you were downloading it. But if you download a piece of software, and the bits don’t add up, then somebody may have tampered with it, and you might be installing a trojan.

    Admin

  3. x264 1080p dts downloader says:

    sometimes when i download my 1080p x264 films using jdownloader or some via bittorrent, they are compressed into multiple rar files and then they contain a sfv file at the bottom of the folder with all of the rar files, now i at least know wut its for, i never ever thought of deleting it before extracting anyway just incase u never know so just keep it till u extracted everything and then delete the sfv along with all of tha rars to get ur precious good lookin free space back on ur hdd homey ;)

  4. someonerandom says:

    haha @x264 1080p dts downloader

    I love your logic, and i feel i am the same way.

  5. ida tarbell says:

    SFV is just a way to evaluate the accuracy. I got a file down and it had one rar file in it, on a Mac Pro. I wanted to have a file with a ‘normal’ digital internet file playable on a usb thumb drive in a smart set. I just clicked the rar file in Mac, though there is no rar conversion in Macs. But my vlc player apparently has one incorporated within. So it played the rar file, but it didn’t convert it for me. So I took the file on a thumb drive to a PC, where my winrar program could convert it. You carry between computers in Fat32 format to access either system. I ran the rar file through the converter. All the other files that were there along with the rar came too. After the conversion I had an mp4 extension file. I pulled the thumb/flash drive (precursor of the Flash Mob) out of my pc and plugged it into the USB input in my LG (semi-)smart TV set. Up popped a series of files, chief among them a pop up of the MP4 file I had created in the PC. I’m watching it now.

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