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PostPosted: Wed Sep 20, 2017 3:50 pm 
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http://www.makemkv.com/errors/read/ says:

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The ONLY reason for this error is inability of the drive to read the data from the disc. This is caused by a damaged disc, failing drive, or both. The error comes from the drive before MakeMKV has an opportunity to look at the data. Nothing else can cause this error - no protection, no software issue - only physical disc or drive damage.


This is a false and misleading claim that can cause users to needlessly replace discs or drives only to find that the error still occurs within MakeMKV.

While physical damage is a obvious cause, these errors more commonly occur due to data mastering errors on otherwise undamaged media. Sometimes those errors repeat across discs and sometimes they don't. Sometimes they occur in the same spot and sometimes they don't. But in almost all cases short of visible, physical damage, these discs will play just fine. They just won't rip.

Most playback software is able to handle these errors, while MakeMKV is not. MakeMKV could handle these errors by interpolating the data or skipping the data across the tiny sections of media that have such data errors. And that omission is MakeMKV's fault — not the user's fault or the disc's fault or the device's fault.

So before MakeMKV exits Beta and can command a $50 price tag, I would encourage its maker(s) to stop treating data errors as fatal and come up with a graceful solution for dealing with imperfect data.


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PostPosted: Wed Sep 20, 2017 5:46 pm 
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Playback software does not "fix" read errors. It ignores them, and skips over the damaged section. If it is just a sector or two that is an issue, you MIGHT hear a glitch in the audio, or see a bit of tearing in the video. If it is several sectors long, the software will try reading until it finds the next valid section, or it might give up and take you back to a menu. If it was not reading far enough ahead, your playback will stop while it decides what to do.

The objective of MakeMKV when ripping is to get a bit-perfect copy of the video and audio. It is necessary if you're going to later process that file with other software - the invalid data will cause decoding errors, which are generally interpreted as "end of file". If you want to "skip" errors, there is software out there that will allow you to do it (Linux ships with the program "dd", which has an option to replace errors with the same number of zero bytes), but the read of that file will fail later, due to invalid data.

As for the error message, what is false about what Mike wrote? The operating system reported that the drive was unable to read the disk. So, either there is a problem with the disk, or a problem with the drive. What other component are you saying is to blame? Maybe the operating system? What other solution are you suggesting?

A dirty disk (most common problem) is a damaged disk that just happens to be easily repairable. A scratched disk is less-easily repaired. A manufacturing defect cannot be fixed by the consumer, except by having it replaced by a disk that isn't from the same batch that had the defect.

Drives can have issues when it comes to switching to layer 2 (a problem that occurs at 4.7GB on DVDs, 25GB on BD) if their laser is out of alignment or the lens is damaged. They'll read many disks without issue, but fail if the movie is too big. Drives can have issues with power, which only show up when the drive is accelerated to something near maximum speed; Those issues will "move around" depending on system load, and are more likely to occur on USB-powered drives.

So, again, what is misleading about Mike's statement, other than that you do not believe it?

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PostPosted: Fri Sep 29, 2017 3:34 am 
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> So, either there is a problem with the disk, or a problem with the drive.

That's the problem. This is not generally true.
The third possibility is that an error was introduced at mastering; possibility even deliberately as is the case with Play Station disc.
They use specialized firmware to deliberate write incorrect ECC codes to the disc.

While I agree that the vast majority of cases are likely actual disc read errors this is a well known technique to thwart ripping.
(I have no perspective on how wide-spread its use is with Bluray movies but it is ubiquitous for Play Station titles.)

I don't know what the old software did differently but there were special ripping programs for Play Station disc that would read the disc at a lower level.
I presume they then did the ECC correction in software and they would retry the read some number of times and would treat a repeated ECC failure as a warning not a fatal error.


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PostPosted: Fri Sep 29, 2017 12:40 pm 
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Quote:
That's the problem. This is not generally true.
The third possibility is that an error was introduced at mastering; possibility even deliberately as is the case with Play Station disc.
They use specialized firmware to deliberate write incorrect ECC codes to the disc.


So, an error in mastering the disk, either deliberate or accidental, is NOT a problem with the disk?

I'm having a bit of a problem with that logic.

But I see your point, when dealing with program/data disks that are deliberately zapped with hard errors that, if not present, mean the disk is fake. That has been around for as long as CDs were used with computers. And Digital Video Disks (the original meaning of DVD) were defined with areas that normal software would expect errors.

That would be a factor if you were trying to duplicate the disk, which is not what MakeMKV is trying to do, and those areas would not be mapped into directory or video tracks.

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