Read Errors on a Blu-ray Disc?
All Blu-ray and HD-DVD discs can be ripped with (provided you have "keep protection" checked using the "rip to image" feature) or without Anydvd HD. They just can't be decrypted without Anydvd HD.
There's nothing on Blu-ray disc that prevents it from being ripped. Blu-ray discs
IN GENERAL do
NOT have a protection that simulates bad sectors on a disc.
- It doesn't matter if you claim the disc plays fine. Simply because a disc plays fine (especially in other drives or standalone players that you're not using to rip this same disc with), doesn't mean it is fine for ripping.
- Yes, Blu-ray media can be defective right out of the plastic wrap. They are also very susceptible to dust and fingerprints (according to James).
- It doesn't matter at all if your disc looks perfectly fine either; it doesn't matter if it looks flawless. Simply because a disc looks fine doesn't mean it is fine.
- It doesn't matter if your drive rips other discs perfectly fine either (other than indicating that your drive isn't the issue--and more than likely your original disc is defective).
- It is also not unusual for bad discs to run in batches. A bad pressing replicated itself over many copies so sometimes getting a new disc is not going to help. All it takes is 1 spec of dust on the press and you have thousands of defective copies.
The only currently known exception to this are
DOD type blu-ray's (
Disc
On
Demand).
Pete said:
There is a certain type of protection, that works with read errors, but it is limited to BD-Rs (on-demand discs you can buy on Amazon, that are burned on regular writable discs, not pressed on BDROM, also no AACS)
As such the above statement
DOES NOT apply to retail / rental discs!
Typically, these are your options in order of likelyhood:
- A. The original disc is bad even if it plays fine. Exchange it, preferably from a different location. "Borderline" bad discs do occur is batches, by the way.
- B. The disc is dirty. Clean it.
- C. Your drive is slowly dying. Try a different drive. (of course if you get the same error on different drives this can't be it, right?)
Read errors are ALWAYS either a defective disc and/or drive.
READ ERRORS ARE IN GENERAL NEVER THE RESULT OF A BLU-RAY PROTECTION!
A detailed explanation by @Pete:
Bottom line: I think CloneBD should get an option to keep trying to re-read smudged discs as an option in the general settings section and / or use error correction - if not used already.
Pete:
There is a persistent misconception regarding error correction. I should make this a sticky, because it comes up every now and then...
It's not something our (or any) software can do, error correction happens on the drive - all the time. Data is stored on discs with a certain amount of redundancy (Picket codes) and, by that, made robust, so a certain percentage of misread bits can be reconstructed.
There are two kinds of read errors - recoverable ones and unrecoverable ones. The only ones you ever get to see are the unrecoverable ones.
Note, that without this error correction active not a single disc, no matter how perfect in condition, will be read without fatal read errors. In other words: those read errors happen all the time, constantly and likewise bits are being routinely reconstructed by your drive all the time. These recoverable read errors and the correction thereof are part of the design (same with DVB, btw.) - recoverable read errors are expected.
Those read errors will not ever surface, you won't notice them and from your perspective the data is in perfect condition. That's the error correction.
When you do actually see read errors, the damage was so bad, that a reconstruction was impossible. At least a block of data (64kB) is screwed up (that's the error correction unit on Blu-ray Discs). There is no way on earth you can reconstruct that or apply some other "magic error correction" - no additional redundancy is available and since these read errors occur block-wise, at least a sequence of 32 sectors is broken at once.
That would be a lot of data to guess.
So at least one frame of video is going to be completely broken. Due to the way AVC and HEVC references frames, this will tear down on average a half second of video (the typical scenario, though, is a group of read errors, multiple blocks).
The only "error correction" means available to CloneBD, is to warn the user about trouble and try to skip the bad area - the video will more or less noticeably skip pictures.
CloneBD already does that - it tries to get past the bad stuff. But only up to a point. Sometimes it's not possible to resynchronize.
Oh... right - re-reading: CloneBD also does that, I think up to 3 times per read error.
