How CRC helps?

[professa X]

SO i get the idea that it will help you verify if YOUR download was corrupted or not but how does it verify whether if the upload it self was corrupted to begin with? All you can say is that YOUR download is corrupted not the original copy. I mean the only way i can think of coming close to verifying if the original was error free is to do multiple downloads but even then that's not 100% perfect.

 

SO please give me the low down cuz i've never used the CRC before!

Edited May 8, 2015 by professa X

[JohnFlower]

What exactly are you asking here? Whether the creators file was 'corrupt' or whether it got corrupted when uploading somewhere? In either case, it's up to the creator to use decent filesharing methods. For mass distribution, torrents or an XDCC bot with md5 and/or crc32 checksums enabled are really the only two worth considering. Also, if you're transferring files for mass distribution, use sftp or rsync.

[professa X]

What exactly are you asking here? Whether the creators file was 'corrupt' or whether it got corrupted when uploading somewhere? In either case, it's up to the creator to use decent filesharing methods. For mass distribution, torrents or an XDCC bot with md5 and/or crc32 checksums enabled are really the only two worth considering. Also, if you're transferring files for mass distribution, use sftp or rsync.

 

okay backgound: someone (hereby know as downloader) commented on a person (hereby known as uploader) upload page that the uploaded anime might be corrupted since the downloader's CRC check kept failing. S im thinking to my self how can you derive that conclusion. TO me it seems that all you can get from a CRC check is whether your download is good or not. Not if the original upload is good or not.

[JohnFlower]

That doesn't answer the question. Does the creators checksum match that of the filename?

Besides that, people creating anime releases should be using AniDB. It saves time and effort.

[professa X]

That doesn't answer the question. Does the creators checksum match that of the filename?

Besides that, people creating anime releases should be using AniDB. It saves time and effort.

im thinking there is a communication barrier here! this is what i was talking about. look at koby's post

 

 

http://kametsu.com/index.php?/topic/40493-multi-naruto-shippuden-mp4mkv/page-10#entry437035

[JohnFlower]

Your question in that thread is clear, but completely different to the one here. If you want to know how checksums work, wikipedia can tell you.

[Moodkiller]

...but how does it verify whether if the upload it self was corrupted to begin with? 

 

To answer this question, a CRC check cant check if the original file (on the uploaders side) is corrupt. The check is just done locally and not against a database. Unless you bring in something like anidb.  

 

However, it can be assumed that if YOUR download failed the check, there is a strong chance something is wrong with the original file. This is also assuming that the uploader is not using a shitty host and/or ruling out file host issues all together. 

[professa X]

 

...but how does it verify whether if the upload it self was corrupted to begin with? 

 

To answer this question, a CRC check cant check if the original file (on the uploaders side) is corrupt. The check is just done locally and not against a database. Unless you bring in something like anidb.  

 

However, it can be assumed that if YOUR download failed the check, there is a strong chance something is wrong with the original file. This is also assuming that the uploader is not using a shitty host and/or ruling out file host issues all together. 

 

MK this is why i keep you around.

[Moodkiller]

MK this is why i keep you around.

Lol! I'm being held against my will?! 

 

I wasnt too sure if thats what you were after, but seems like it was close to it. 

[professa X]

 

MK this is why i keep you around.

Lol! I'm being held against my will?! 

 

I wasnt too sure if thats what you were after, but seems like it was close to it. 

 

yea close. basically what i got fro your answer was this:

if we assume that the filehost service host is not shitty

then when we run crc checks, all were doing is verifying if the uploader uploaded a good file.

[Moodkiller]

yea close. basically what i got fro your answer was this:

if we assume that the filehost service host is not shitty

then when we run crc checks, all were doing is verifying if the uploader uploaded a good file.

 

Correct. All other variables aside, that's the bottom line. 

 

A point where this theory fails would be when I used exrapidleech to import a file from my Mega account, so that I could remotely upload it to my Uptobox account. The crc check failed on the imported file now stored on exrapidleech (due to a faulty plugging I assume), however the original file that I had up on Mega was fine. This thus lead to a corrupt file when downloaded from Uptobox and a perfectly fine file when downloaded from Mega.

 

^No real point, just felt like relaying a real life example. 

[Koby]

If I download the same file three times and they all fail CRC check and all show the same CRC then you can assume it's a faulty upload.

 

If I download the same file three times and they all fail CRC check but all show different CRC then apparently the host is shit and keeps corrupting the file each time at a different spot.

[professa X]

If I download the same file three times and they all fail CRC check and all show the same CRC then you can assume it's a faulty upload.

 

If I download the same file three times and they all fail CRC check but all show different CRC then apparently the host is shit and keeps corrupting the file each time at a different spot.

Thanks. Sometimes you gotta spell things out to me. BAMF