Dycrypt a scratched DVD: ddrescue + DVD Decrypter

[spitfire_ch]

Having spent quite a lot of time trying to rescue a scratched DVD, I thought I could share my findings here. This is certainly not the ultimate guide; it's just what worked for me in the end.

The starting situation was a scratched disc of a TV show with four episodes, two of which could be played in full, one of which had a missing ending, and the other had a missing start. To prevent further damage, I wanted to make a backup of the disc and save as much as possible. MakeDVD only copied the two undamaged titles, while DVDFab created a completely unreadable ISO. The ISO created by ddrescue alone could be mounted but video was garbled due to encryption. Using a combination of ddrescue and DVD Decrypter, I was able to create a working ISO. The damaged sections are still missing, but the image is much easier to play than the physical disc (which constantly revs up the drive).

Steps on Linux (ddrescue)
1. lsblk → identify the DVD drive, sr0 or sr1
2. sudo apt install gddrescue (if ddrescue is not already installed)
3. ddrescue -n /dev/sr0 dvd.iso rescue.log

It will run several passes, each pass with "finer resolution" working on the difficult sectors, and can be aborted using Ctrl + C at any time. In my case, it made no more progress in pass 5 after 1 - 2 hours, with > 1 h since the last successfull read. Running it longer is not recommended because it will hardly recover anything anymore and just wear the drive down.

Copy the iso to a Windows machine.

Steps on Windows (DVD Decrypter)
1. Install DVD Decrypter
2. Mount the encrypted, rescued iso-file
3. Launch DVD Decrypter, using the virtual drive as a source
4. File → Decrypt

5. Click YES, and then YES to all
6. Errors will pop up every now and then:

7. Click OK for each of them

The final ISO can either be opened directly in VLC or mounted as virtual drive and used by other media players. I have not tried to burn that image.

[hajj_3]

blindwrite exists.

[spotter]

assuming one has an rpc2 drive I think one has to authenticate the disc to the drive first before using ddrescue (lsdvd can do that).

[kurkosdr]

I question the purpose of ddrescue in the chain, since DVD Decrypter allows you to ignore read errors and also specify the number of retries:



Don't get me wrong, if you want to make an encrypted ISO of the disk without decrypting anything, I can see the point of ddresuce (though the resulting encrypted ISO will be useless in "licensed" DVD players, you have to use something like VLC or MPC-HC that will brute-force the encryption, since the key required for proper decryption will not be present in the ISO).

But if you are decrypting with DVD Decrypter (which means reading the VOB files and decrypting them), ddrescue seems useless.

Also, keep in mind that:

- Some DVDs have purposely bad sectors as a form of copy protection (in areas of the VOB file not read by DVD players), and for such discs, not all your read errors will be actual disc damage, this applies to both DVD Decrypter and ddrescue

- Some DVDs have a purposely malformed TOC (table of contents) that will make the DVD seem as dozen gigabytes in size (see here for an example, I was able to solve the issue with the free edition of DVDFab, see here for details), this will not affect encrypted ISOs created with ddrescue but will affect files created with DVD Decrypter

EDIT: DVD Decrypter can defeat the bad sector copy protection for discs released before its development stopped, but not for discs released after, so yeah, it will still exhibit the issue on some discs

[spotter]

the point of ddrescue is when dealing with a scratched DVD (or bluray). Imagine you have 2 or more copies of the same disc (say from your local public library). what's the easiest way to get a complete image of it? ddrescue. Yes, bad sector protection will show up as bad sectors as well in ddrescue, but generally they are a pattern one can recognize.

[StainlessS]

Originally Posted by kurkosdr

EDIT: DVD Decrypter can defeat the bad sector copy protection for discs released before its development stopped, but not for discs released after, so yeah, it will still exhibit the issue on some discs

Not sure about this but, I think that RipIt4Me + DVD Decrypter combo works ok, RipIt4Me provides a list of of bad sectors to DVD Decrypter, which then does it's magic. (Anyway, has more success than DVD Decrypter alone).

EDIT: I usually skip the DvdShrink step of RipIt4Me.

[Emulgator]

Plus I would suggest to polish the disc with a disc polish.

[StainlessS]

Originally Posted by Emulgator

Plus I would suggest to polish the disc with a disc polish.

And run under the cold tap afterwards to remove polish, then shake dry.

I actually use "spray-on" alcohol based Covid hand cleaner to clean disk, then water to remove glycerine in hand cleaner.
I dont use polish usually, some suggest toothpaste + water.