I would like to report here my experience of trying to recover/restore data from a damaged BluRay-Disc (BD). Maybe it will be interesting and/or useful for somebody else...
- Specifications of the damaged disc:
Disc Type: BluRay-Disc DL 50GB
Disc Title: BATTLESTAR GALACTICA - S2 D3
Disc Label: BATTLESTAR_S2_D3
Data Size: 48.402.722.081 Bytes (45,08 GB)
Data capacity: 46.38 GB
Sector Size: 2.048 Bytes
Sectors used: 236.365.12
Protection: AACS v18
Timestamp: 2010-06-16 09:00:09
Layers: 2
Channel-Bitsize: 74,5 nm (max. 25.0 GB per Layer) -
Specifications of the used drive:
OS-Devicename: \Device\CdRom0
Recent Profile: BD-ROM
Manufacturer: PIONEER
Product: BD-RW BDR-S08
Revision: 1.30
Serial-Number: MDDXXXXXXXXX
Firmware-Date: 2013-07-08
Marks of Bus-Encryption: 1B
Highest AACS Version: 52 -
LibreDrive Information:
Status: Enabled
Drive platform: RS8301
Firmware name: PIONEER BDR-208
Firmware type: Original (unpatched)
Firmware version: 1.30/ID43
DVD all regions: Yes
BD raw data read: Yes
BD raw metadata read: Yes
Unrestricted read speed: Yes
After 10 years of owning the complete collection of the Battlestar Galactica series (22 BDs),
I realized that my Panasonic DTS (Digital-Theatre-System) has some playback-issues with 2 of the discs.
So I decided to make private backup copies of all of them, to prevent eventually more issues in the future.
Said and done - everything went fine with MakeMKV until I came to disc 3 of season 2.
After around 50% MakeMKV started to throw a lot of uncorrectable read-errors to the LOG and stopped processing.
So I started to inspect the surface of this disc...
After a short time I saw a "funnel-shaped notch" in the middle data-area of this disc, with a size of 2-3 mm in total. As its position matched with the progress of MakeMKV, before it stopped processing, I thought that the reason was found.
But what to do now?
5. (possible) Solutions:
At first I thought it was a physical damage of the protection-layer.
But as this layer is only 0,1 mm thin on BluRay-Discs, I wouldn't use some polish stuff or other things that are removing parts of the surface.
So I came to the conclusion, that something which fills up the damaged area would be a much better solution. (There are some kind of "Disc-Repair-Sets", for such purposes, in Media-Stores out there.)
But as I still had a tube of "transparent liquid Acryl" at home (for filling scratches in the coating layer of cars) I decided to try this at first.
Said and done - but I couldn't see any improvements afterwards.
So I tried to feel with my fingertips if there really is a physical damage.
My impression was: no.
Visually yes, but sensual perceived no.
Then I used a strong magnifying glass for further investigations.
With this tool and direct daylight I was able to detect that the coating layer is still intact, but the actual data-layer (foil) shows some irregular structures - in shape of a "spiral of dots".
The final result was: a manufacturing defect or burn-error.
So there wouldn't be any solution at all to "repair" this disc.
My next step was trying to recover as much data as possible from this disc.
For this purpose I used a tool called "ISOpuzzle".
It creates an ISO archive of any optical media, at sector level.
During the first run it saves all intact sectors and skips all defect sectors.
Beside it creates a database with a map of all sectors.
Within this database it marks sectors without errors as "good" and sectors with uncorrectable read-errors as "bad". In future cycles it just skips all "good" sectors and processes only the "bad" sectors (which will save a lot of time).
But the best feature of ISOpuzzle is a mode called "never give up".
So you can let it run beside, over days and nights, without paying attention to it.
But in spite of processing only the bad sectors, it still needs a lot of time!
Depending on the specific nature and size of those bad sectors, of course.
(Hint: "Cycle Tray" and "Allow Cooldown" under "Permanent Failure" should always be activated - to prevent damage from the drive because of excessive use!)
6. Process (noticed at random times):
After the first run of ISOpuzzle there were 155.858 bad sectors remaining, which corresponds to 319,20 MB (in my specific case).
After 124h36m there were 29.495 bad sectors remaining (60,40 MB) / recovered: 258,80 MB in total
Some screenshots/graphics for better illustration:
- ISOpuzzle after 27:34:59
- BSG_S2-D3_ISO-Puzzle_01.png (14.67 KiB) Viewed 201 times
- ISOpuzzle after 124:36:30
- BSG_S2-D3_ISO-Puzzle_02.png (11.72 KiB) Viewed 201 times
- Statistic / Diagram of the whole Process
- BSG_S2-D3_ISO-Puzzle_Recovery.png (138.87 KiB) Viewed 201 times
So 81% of all "marked as bad" sectors from the first run were recovered!
Which is amazing, as I never expected such a high score.
At this point I stopped the process, because the number of successful read sectors per loop reached a one digit level and often was zero.
So the ratio of recovered sectors vs. running time diverges too far.
After this long process I mounted the resulting ISO, copied the corresponding (damaged) file
"/BDMV/STREAM/00004.m2ts" to the MakeMKV-Backup-Folder of this disc and started another attempt to save this episode as ".mkv".
MakeMKV still showed some uncorrectable read-errors in the LOG but didn't stop processing now.
So I thought I did it...
But as I watched this episode to check again which area(s) will still be affected, I was disappointed.
After the first run of ISOpuzzle there were 2 faulty areas within this episode:
6 Seconds from 36:40 to 36:46 as well as 58 Seconds from 37:10 to 38:08 (without audio and a lot of picture artefacts).
After the last run of ISOpuzzle there still was this longer faulty area (only slightly reduced):
38 Sec. from 37:10 to 37:48.
So only 26 Seconds were "won". (Which was not what I expected.)
Unfortunately these remaining damaged 38 Seconds were during a scene of heavy conversations and missing them would result in missing important informations for future scenes.
Ignoring this fact wasn't an option for me.
If this area of uncorrectable read-errors would only contain data from another foreign language audio track, some Bonus-Stuff or unimportant scenes without conversations, I'd never had a problem to delete them with "lossless cut" or leave them out during processing with MakeMKV. But...
In the end I re-ordered the complete season (used for 8,-€) and was able to save this episode in a few minutes, without any errors. (Hahaha...)
7. Conclusion(s):
Tools like ISOpuzzle are great for optical disc recovery - if time doesn't matter and for the first attempt (without financial output).
If there are only some small scratches in the protection layer of the disc, you will propably be good using some "transparent liquid Acryl" or special "Disc-Repair-Sets" from Media-Stores in addition.
DON'T USE ANY STUFF WHICH "REMOVES" PARTS OF THE SURFACE, such as all kinds of polish!!!
In case of BluRay-discs you will quickly ruin your disc by grinding off the 0,1 mm protection layer, which will result in a nice decoration disc!
In case of manufacturing defects or burn-errors you'll have no chance to recover anything from the faulty area(s). It would be like trying to read data from a saucer or a slice of salami.
8. personal comments:
I have 20 years old CDs/DVDs here, which are looking like used as a doormat, frisbee or saucer.
CDs used in the car for years (before MP3 at USB-Sticks were born), wandered from the trunk to the front floor and back a hundred times (of course without a protection case).
If you would see them, you would never expect them playing without any issues - BUT THEY STILL DO!
Why?
Because the thickness of their protection layer is up to 1 mm (instead of 0,1 mm at BluRay-Discs).
The density of their data channels is much lower than those of BluRay-Discs.
They are more flexible (softer) than BluRay-Discs.
In my opinion and according to my experience with both of them, I think BluRay-Discs will be a dead-end in optical storage.
Of course, their protection layer is much harder than those of CDs/DVDs, but this "advantage" is neutralized by its thinness.
Furthermore: harder = more brittle!
One day a BluRay-Disc accidentally slipped from my hand and touched the (ceramic) floor tiles upright - it shattered like glass into thousand pieces...
But I never experienced something similar with CDs/DVDs.
So BluRay-Discs are a typical case of disc-size vs. durability/sensitivity.
I've got another BD which has a circular scratch with a length of less than 1 cm - if I put it in the Panasonic player, the player goes like: "mi mi mi - we don't do that here"!
If I put a heavily (circular and radial) scratched DVD in the same player, the player goes like: "ah, welcome - I don't see any issues here and will play the whole movie without getting stuck somewhere"!
Anybody here who understand or can explain this?
As TerraByte-sized external USB-HDDs are less expensive today, I decided to backup all my BluRay-Discs to them, before more and more of my BDs eventually going to hell.
Fortunately the BD-drive of my PC is less sensitive than my Panasonic player - so the previously mentioned (scratched) BD passed the backup process without any errors.
End of Story