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Old 6th April 2024, 13:38   #1  |  Link
Katie Boundary
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How accurate are the ISO files made by MakeMKV?

I know that many CD-cloning programs omit or alter parts of the data, particularly the parts related to copy-protection, and I was specifically wondering if MakeMKV had a similar weakness when cloning DVDs.
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Old 6th April 2024, 16:22   #2  |  Link
coricopat
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Originally Posted by Katie Boundary View Post
I know that many CD-cloning programs omit or alter parts of the data, particularly the parts related to copy-protection, and I was specifically wondering if MakeMKV had a similar weakness when cloning DVDs.
For decrypted backups, it will of course at least change all files that need to be decrypted.
For encrypted backups, you could easily check that by diffing an image you created with a program for which you know it makes a true block copy (like dd under linux) with that what MakeMKV produces.
I think it did that, and there were no differences - but that's of course no general proof.
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Old 6th April 2024, 18:25   #3  |  Link
Katie Boundary
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Originally Posted by coricopat View Post
For decrypted backups...
For encrypted backups...
MakeMKV doesn't seem to give me a choice. The checkbox is grayed out.
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Old 6th April 2024, 18:39   #4  |  Link
coricopat
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Originally Posted by Katie Boundary View Post
MakeMKV doesn't seem to give me a choice. The checkbox is grayed out.
Does it? Okay, maybe I remembered wrong.

Well you can always just make a dump of the image with a tool like dd.

Some devices complain about scrambled sectors, in that case, just play the disc with a tool like mpv and libdvdcss before, that should authenticate it.

(not sure about Windows counterparts ... sry)
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Old 14th April 2024, 03:37   #5  |  Link
Katie Boundary
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Originally Posted by coricopat View Post
Well you can always just make a dump of the image with a tool like dd.
"But on mixed-mode CDs you would end up losing the audio part of the CD as ISOs only are copies of track 1 on the disk. Same applies for creating a backup with Linux's dd utility." -https://linux.goeszen.com/how-to-copy-a-mixed-mode-cd-rom-to-disk.html

So even dd isn't guaranteed to do it correctly.
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Old 14th April 2024, 10:52   #6  |  Link
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I'm not entirely sure what it is you're aiming for here, Katie, but you might want to look into something like MPF (Media Preservation Frontend). It's a GUI for dumping all sorts of discs with the aim of creating 1:1 copies. It's primarily aimed at people dumping video games but covers a very broad range of optical media.

I use it primarily for PS3 discs but have dumped a couple which were hybrid discs containing regular blu-ray video sections, and have also dumped some regular blu-ray discs, just to see what would happen. Because they're 1:1 copies the AACS folder is still present and they play fine via VLC when the .iso images are mounted but the .m2ts files are still scrambled if you just try and play them directly off the disc, unlike with a decrypted disc image.

I know that only certain types of drive are capable of reading and dumping PS3 discs (the drive that came with my PC just happened to be one of them) but I think any drive that can read regular movie discs should work for anything you're trying to do.

https://github.com/SabreTools/MPF
http://wiki.redump.org/index.php?title=Dumping_Guides

EDIT: I've just re-read what you originally said and you were talking about DVDs so apologies for going off at a tangent about blu-ray discs... just got them on the brain, really! I've also dumped 1:1 copies of DVDs using the above and the same applies as with blu-rays: encrypted image comes out as garbage if you try and play individual files but VLC etc will decrypt the disc image fine. Hope that's of some use.

Last edited by richy; 14th April 2024 at 12:43. Reason: Note to self: Read the post properly in future! ;-)
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Old 14th April 2024, 23:19   #7  |  Link
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Originally Posted by Katie Boundary View Post
"But on mixed-mode CDs you would end up losing the audio part of the CD as ISOs only are copies of track 1 on the disk.
I guess I misunderstood you're request a bit and totally forgot about multitrack/multisession mediums.

Actually I wasn't even sure whether BD's would still support that (presumably, I guess).

But - and there's no sarcasm or so in this - has anyone ever seen a mutlitrack/session (Video) DVD or BluRay?


Of course, dd would only retrieve any "actual" data (and that only from track 1, and I presume from that last session, if multiple).
Neither would it get stuff like subchannel data.

I don't have much clue about what things like subchannel data there is on DVDs/BDs... most likely they still have some ECC ... but has anyone in the movie area (not talking about game copy protections or so) ever used that for any actual data?

Cheers,
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Old 15th April 2024, 02:15   #8  |  Link
Katie Boundary
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Originally Posted by richy View Post
I'm not entirely sure what it is you're aiming for here, Katie, but you might want to look into something like MPF (Media Preservation Frontend). It's a GUI for dumping all sorts of discs with the aim of creating 1:1 copies. It's primarily aimed at people dumping video games but covers a very broad range of optical media.
Oh, very cool. I'll definitely look into that for game backups!

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Originally Posted by coricopat View Post
But - and there's no sarcasm or so in this - has anyone ever seen a mutlitrack/session (Video) DVD or BluRay?
That is indeed one of the big questions. Wikipedia mentions that "CSS prevents byte-for-byte copies of an MPEG (digital video) stream from being playable since such copies do not include the keys that are hidden on the lead-in area". What is the "lead-in area"? Is it a separate track? If not, will MakeMKV include it in the ISOs, even if it isn't necessary?
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Old 15th April 2024, 23:11   #9  |  Link
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What is the "lead-in area"? Is it a separate track? If not, will MakeMKV include it in the ISOs, even if it isn't necessary?
AFAIU, it's not really a track, but there's a lead in before the first track and a lead out after the last track of each session.
Use to position the laser, etc..

in CDDA days it was possible that audio data actually went into the lead-in/out and some drives (e.g. good old plextors) could overread into those to get the data.
No sure whether it was possible to always read the full lay out or just some blocks.


Maybe you've seen that thread of mine:
https://forum.doom9.org/showthread.php?t=185295
which I still don't exactly why that happens ...

I tried to read the UHD from there with cdrdao:
Code:
# cdrdao read-cd --device /dev/sr0 --read-raw --datafile image.bin  image.toc
Cdrdao version 1.2.4 - (C) Andreas Mueller <andreas@daneb.de>
/dev/sr0: PIONEER BD-RW   BDR-S12U      Rev: 1.02
Using driver: Generic SCSI-3/MMC - Version 2.0 (options 0x0000)

Reading toc and track data...
ERROR: Cannot read disk toc.

Track   Mode    Flags  Start                Length
------------------------------------------------------------
 1      DATA    4      00:00:00(     0)     xxxxx:xx:xx(40000000)
Leadout DATA    4      xxxxx:xx:xx(40000000)

ERROR: Cannot read sector of track.
WARNING: Cannot determine mode of data track 1 - assuming MODE1.
Copying data track 1 (MODE1_RAW): start 00:00:00, length xxxxx:xx:xx to "IMAGE.bin"...
Found L-EC error at sector 0 - ignored.
Found L-EC error at sector 1 - ignored.
Found L-EC error at sector 2 - ignored.
Found L-EC error at sector 3 - ignored.
Found L-EC error at sector 4 - ignored.
....
So looks like the part that the UDF and whole block device seems to somehow use, may all be in the lead-out.
I'd guess there's not really anything in it, though.

Cheers,
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Old 18th May 2024, 06:43   #10  |  Link
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I didn't understand any of that lol
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Old 20th May 2024, 06:48   #11  |  Link
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Copy protection schemes are (expensive and useless) evil.
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Old 21st May 2024, 02:02   #12  |  Link
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Well you can always just make a dump of the image with a tool like dd.

Some devices complain about scrambled sectors, in that case, just play the disc with a tool like mpv and libdvdcss before, that should authenticate it.
Problem is, when it comes to DVDs with structure protection (that is, RipGuard or ARccOS), dd will fail when it reaches the corrupted sectors.

In simple terms, structure protection works by inserting some minutes of black frames (or other filler video) in the middle of the movie. Those filler minutes are skipped using DVD-Video's "seamless branching" feature (the same feature which allows a DVD to have multiple versions of a movie, for example a regular and "extended" version, with the scenes that are part of the "extended" version skipped in the regular version), with the difference that when it comes to structure protection, the "full" version of the movie (with the filler minutes) is never exposed in the DVD menus. Then disc read errors are purposely introduced in the sectors containing the filler minutes during the glass mastering stage.

The end result is that copying software unaware of this copy-protection scheme will try to copy the whole VOB file (or the whole filesystem), hit multiple corrupt sectors, and fail. While it's possible to set the disc read error limit to infinity in some software (ddrescue for example) and set retries to 0 to minimize the time spent slogging through the corrupted sectors, it's still very taxing on the optical disc drive and the process can take several hours.

So, no, dd (or ddrescue) will not work unless you are willing to reduce the lifespan of your optical disc drive.

In order to make it happen, you need a map of the corrupted sectors and a program that can replace them with "dummy" sectors while leaving anything else untouched. DVD Decrypter used the "dummy" sectors approach, but I don't remember if it can do an 1:1 ISO copy otherwise. Also, DVD Decrypter doesn't defeat structure protection in all DVDs either because its development stopped rather early.

Last edited by kurkosdr; 21st May 2024 at 11:49.
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