Options for trying to back up scratched discs?

[fullmental]

Hi, I have a *very* expensive box set I'm trying to save to my hard drive using MakeMKV, but one of the discs apparently got scratched in one of the players at some point, because there is a small but severe circular scratch about halfway through the main feature. This is preventing the disc from being saved due to the following error:



I've read enough of the problem threads here to know the scratch is the most likely problem. I've tried increasing the retry attempts to 99 but it doesn't help. How can I get around this and salvage as much of this disc as I can? The box set is $200 to replace so it's not practical to do that, and the studio isn't responding to my attempts to contact them for a replacement disc. I was considering buying a new bluray drive for my PC anyway, might that help? If so, what model is most forgiving of scratched discs in general? I currently have the LG WH16NS40, which was about the cheapest I could find that had writing capability back in 2014.

[Woodstock]

Levels of escalation of cleaning:

Damp soft cloth.
Waxing.
Polishing.
Resurfacing.

I've recovered many disks with MINOR scratches using Pledge furniture polish. Spray it on, rub it in with a clean finger, wipe off with a soft cloth, let the water dry off, pop it in the drive to rip it. The wax fills the scratches enough that the laser can see through them to the data.

If that won't work, manual polishing with a low-abrasive polishing compound can work. No jokes about "minty fresh", but a lot of tooth pastes qualify, if you don't have jewelry cleaning polish available. But you have to be careful with this, as you can damage the disk if you get too aggressive.

Proper resurfacing should be done with the right equipment. A lot of video rental shops will resurface a disk for a small fee. This is the same process that Netflix and others use to simply remove enough of the surface to take out the scratch, but it's not reversible. Once started, you're committed to finishing it, which is why having it done by someone who knows what they're doing is important.

[thetoad]

I have a solution which I can't use with makemkv yet for BRs but works fine for DVDs if you can get access to another copy of the same DVD (and I'm hoping eventually BR)

I've written about it here before basically for DVDs

needs Linux (though conceptually should work with windows 10 linux mode or cygwin)

assuming /dev/dvd is the optical device

1) run lsdvd /dev/dvd

this authenticates the drive with the disc, otherwise you'll get read errors for every scrambled sector I believe

2) ddrescue -v -b 2048 -d /dev/dvd name.iso name.log

this will read the disc in blocks of 2048 bytes (the DVD block size) in direct mode and will write the output to name.iso and keep a log name.log with what sectors it was able to read and what it wasnt.

now we are going to assume the disc wasn't fine.

so you get a different copy of the disc that might also be scratched in different places

so run ddrescue again, but tell it to retry the bad sectors (or just continiously retry)

3) ddrescue -MA -v -b 2048 -d /dev/dvd name.iso name.log

or ddrescue -r -1 -v -b 2048 -d /dev/dvd name.iso name.log

if it completes with no errors, you now have a bit for bit copy of the original DVD with scrambled sectors. This isn't actually terrible, vlc can play this iso as is, but most tools wont work as they expect an iso to be descrambled.

but this is where an old standby comes in handy. dvd decrypter.

dvd decrypter can't handle many of the new protection schemes for DVDs, but we don't care about them, all we want it to do is read an iso (mounted) and write an iso without doing anything else. it can brute force the css and output a descrambled iso image. I've also put some work into making a simple c/c++ program that can do it in place (i.e. not writing out a whole new iso image, just rewriting the scrambled sectors), but my last version broke it so I've been mostly using the dvd decrypter method)

anyways, the above method works great for DVDs (if you can get access to another copy, it can be damaged too, just as long as not damaged in same places)

I want to start attacking this for Bluray images, but dont know enough about how AACS works and if one can make a bitwise backup and then decrypt that bitwise backup without it being in a drive. opinions on this would be appreciated.

[Davidsmith150]

I would normally use AnyDVD (on Windows) to take a backup of a DVD with copy protection, but is doesn’t seem to handle read errors very well (e.g. discs have small scratches) and copies fail.

GNU ddrescue (gddrescue, ddrescue, NOT dd_rescue) on linux is supposed to be better at handling small errors and is designed to handle read errors.