AnyBDMV: Movie recovery product

Discussion in 'General Chat' started by markfilipak, Sep 17, 2018.

  1. Pete

    Pete Forum Admin Staff Member

    By "raw read" just means: "read the bits and don't bother with error checking or correcting". When you copy files from the disc, the whole mechanism, including error correction is fully at play.
    Raw reading would be necessary for any statistical method to even be possible.
    Then you'd have to do the error correction yourself - and be faced with the same problem again. You don't know, which bits are bad. Statistics don't help - many of those bits will persistently be flipped the wrong way (the error correction mechanism will fix them, but only if.... ah, well I already explained that).
     
  2. markfilipak

    markfilipak Well-Known Member

    That's the reason to read over-and-over (and over, and over) and scoreboard the results... To statistically get a better idea where the 'bad' bits are. The bad bits are going to be the ones that change. And most prevailent values are probably the best values available. If the 'really bad' bits can be isolated to fewer video frames, then dropping those fewer frames will result in the least loss.

    ...You don't need to reply unless you really want to.
     
  3. thetoad

    thetoad Well-Known Member

    I've literally been doing this for the past decade+ with ddrescue for DVDs and BRs (and a set of non bus encryption drives for BRs). Create an encrypted BD ISO with ddrescue and then can use anydvd to decrypt BRs and dvddecrypter (iso to iso mode) to decrypt DVDs by using an iso mounter. ddrescue will tell you how much of the disc is read and enable you to fill in the blanks from other media if one can get access to it. bad areas will be unencryptable.
     
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  4. markfilipak

    markfilipak Well-Known Member

    @thetoad

    Thanks for your post...

    Ah! I forgot about bus encryption. So, ddrescue can raw read a non-bus encrypted drive. Of course. Do you have a source for such drives? PM me if you prefer.
     
  5. thetoad

    thetoad Well-Known Member

    There's a thread on doom9 with them, source is used on ebay

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  6. thetoad

    thetoad Well-Known Member

    I'd also note, that you don't get a set of "bad bits" on a fail to read. You get nothing. The drive says read failed if it can't return bits the pass the on disk error correction codes. So it's essentially all 0s

    I.e. this isn't like a CD where you can actually read it in a raw mode and do cdparanoia magick.

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  7. markfilipak

    markfilipak Well-Known Member

    How large are the fail blocks? Are they 1 sector (2048 bytes)?

    PS: Can you read the ECC bits for failed blocks?

    PPS: A little thought... I think I could mod the drive to capture the raw data.
     
    Last edited: Oct 8, 2018
  8. thetoad

    thetoad Well-Known Member

    At that point you are in custom tool territory and outside the scope of anydvd I'd think.

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  9. markfilipak

    markfilipak Well-Known Member

    Indeed. It would be a hardware/software product. ...Why not? Imagine large. I have tools and I have $.