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Mike Admin: Concerning Bitwise Correctness Of Ripped Files

Posted: Thu Sep 01, 2011 1:43 am
by goingbust
I wanted to ask, assuming that a rip comes back with no errors, are the output files guaranteed to be 100% correct (i.e. the 100% correct cleartext of the encrypted file)? Stated another way: Does even a one bit error on the disk caused by dirt or a scratch that the disk mechanism cannot correct for cause an unrecoverable error every time in MakeMKV? Or does it make some "reasonable guess" to correct for it? The reason I ask is that there have been a (very) few files that I have ripped without any errors being thrown by MakeMKV that when played in VLC will cause VLC to bomb during playback at certain well defined points. If I restart VLC, it will bomb again at the same place, so it is reproducable. So I wonder if this is because MakeMKV didn't produce exactly the correct file, or if there is a problem on the blu ray as mastered (i.e. the studio screwed up), or if it a VLC problem. Of course there may be other issues such as the file getting corrupted between being ripped and being read, but I hope that is not the case, I am using very modern equipment and a very clean OS install.

Anyway, in general, how does MakeMKV correct or try to correct for media errors?

Thanks for any insight.

P.S. The program is still great and is worth every cent I paid for it.

Re: Mike Admin: Concerning Bitwise Correctness Of Ripped Fil

Posted: Thu Sep 01, 2011 2:37 am
by setarip_old
Do you have VLC reading a disc or from your hard drive?

Re: Mike Admin: Concerning Bitwise Correctness Of Ripped Fil

Posted: Thu Sep 01, 2011 3:26 am
by goingbust
setarip_old wrote:Do you have VLC reading a disc or from your hard drive?
It's reading the ripped .mkv file from my primary hard drive which is a WD 1 TB drive.

Re: Mike Admin: Concerning Bitwise Correctness Of Ripped Fil

Posted: Thu Sep 01, 2011 10:09 am
by mike admin
Generally, MakeMKV will usually fail if files are damaged. At least it won't ignore the error silently.

For blu-ray there is a way to be sure that files are correct. Unlike DVD, blu-ray discs have hash files stored for each M2TS file, so one can check the hash after M2TS file is copied to be sure that no error happened. Usually about 99% of m2ts file is hashed and MakeMKV automatically validates these hashes during full backup. These hashes are not validated during regular conversion, so to be sure you need to make a backup first and then make an MKV file from this backup. I don't know any other software that can validate these hashes, especially during file copy.

Re: Mike Admin: Concerning Bitwise Correctness Of Ripped Fil

Posted: Thu Sep 01, 2011 4:15 pm
by goingbust
Thanks for the explanation. I have not done a full backup, I use the one step process and just rip right down to MKV files. Since I just watched one of those files - Kill Bill Volume 2 which kills VLC in a very specific place and I have that disc in my llibrary, I am going to try that out tonight and see if it reports any errors during a full backup.