Why don't copy protections cause problems on stand-alone DVD players?

Discussion in 'General Chat' started by mwb1100, Feb 1, 2008.

  1. mwb1100

    mwb1100 Active Member

    In a different thread I saw this comment:

    Now I've wondered several times about this, and I figure some of the people on this forum can probably educate me.


    DVD protections are:
    • complex (I'd think),
    • continually changing, and
    • break standards
    And many or most DVD players (particularly cheap ones?) are:
    • simple, single function devices (more or less),
    • never change or get upgraded,
    • rely on standards to know how to play the movies

    Why do the protections that cause so much pain and suffering on PCs have pretty much no impact in my DVD player?
  2. Webslinger

    Webslinger Retired Moderator

    Last edited: Feb 2, 2008
  3. Pelvis Popcan

    Pelvis Popcan Well-Known Member

    But that's not the case the majority of the time. For example, there are a great many stand-alone players that can play Saw III. But it's loaded with copy protections that mess up optical drives unless a program like AnyDVD is used.

    mwb1100, I think that's a very good question!
    Last edited: Feb 1, 2008
  4. Webslinger

    Webslinger Retired Moderator

    And some won't (one of my friend's standalones won't).

    "Many older (or less sophisticated) players simply skip these corrupted areas as unreadable and continue on. Computers -- and unfortunately, some newer players -- try to perform error correction on these areas and fail playback." (this applies to Sony's protection before it was changed)
    Last edited: Feb 1, 2008
  5. mwb1100

    mwb1100 Active Member

    I wasn't aware of the troubles that the Engadget article mentioned. It figures that Sony would be then one to cause a widespread screw-up on DVD players.

    That makes sense.

    Also, I didn't mean to be misleading in the thread title - I was really just curious about how the protection technology worked (without getting too technical and obviously without getting into proprietary details). From an academic standpoint, it's an interesting problem that's nearly a paradox - how do you put out a single stream of information that's supposed to be publicly readable on one set of widely available devices, but not on another set. It seems similar to saying you want to publish a dead-tree paper book that gets sold in regular bookstores that women can read but men can't.

    Clearly crypto is one possible answer, and CSS was an attempt to do that. But CSS was circumvented a long time ago (for more than one reason, as I understand it), and new crypto could not be added to the huge set of existing machines. So new protection methods would seem to have to use something that's different from crypto.

    From reading here it seems that the protections use a variety of things like bogus files, bogus file metadata (sizes, etc. I think), and structural protections (whatever they are). For the time being, lets leave aside the gnarly Sony stuff that does seem to break on stand-alone players. I'd guess that the vast majority of protections do not cause problems on the vast majority of players (otherwise Blockbuster would have been out of business a long time ago). Also, let's leave aside whatever AnyDVD does to undo these protections.

    So to wrap up my long question with a long summary of the question: why do these protections confuse or cause problems on PCs but not standalones? I'm not trying to gain any 'insider' information or figure out how to write AnyDVD or say that there's not much complexity to what AnyDVD does. Believe me, I wouldn't understand it at that level - I'm more looking for the level of detail that 's given to a topic on the howitworks.com website (you know, picture-book level). And, of course, I have no *need* for this information, I'm just curious.

    Maybe the answer is simply in the fact that PC's get hung up on error-correction. But I would have thought there would be more to it than that.
  6. DrinkLyeAndDie

    DrinkLyeAndDie Retired Moderator

    Even X-Protect doesn't claim their protection works on all standalone players or PC drives. I greatly dislike them but I respect the fact they don't claim it's 100% compatible. I don't, however, believe the number is as high as 99%, though, either.

  7. Webslinger

    Webslinger Retired Moderator

    Simply stated, standalones do not rely on the same system of playing a disc as PCs do. With protect-dvd, the file structure is corrupted with multiple files appearing with the same file name, 1GB .ifo files, sectors that overlap each other, etc. And software players on PCs do tend to look for files based on a normal file structure. Anydvd patches the UDF file system on these discs so that they work in PCs. Often these discs are unplayable in PCs without Anydvd. Standalone players mostly just reference video_ts.ifo and follow the (sector) path as provided in video_ts.ifo, which is sufficient to tell the player what to read. At least this is my understanding. However, not all standalone players necessarily function in the same manner. Some standalone dvd players do have problems with protect-dvd discs, and I believe what Drinklyeanddie is quoting with respect to 99% is nothing more than pure marketing nonsense.

    Perhaps James or peer will clarify/correct some of the things I've written here.

    You really can't because protect-dvd, fluxdvd, etc., also cause problems with some standalone dvd players, regardless of 99% claims of compatibility.

    Anyway, I doubt I'll be posting much more in this thread. I prefer trying to help people with troubleshooting problems, which tends to eat into my free time.

    James and peer will have the best answers for you (probably much better than mine). After all, they programmed Anydvd to handle these protections so that the original disc can be played on your computer. They are the masters.
    Last edited: Feb 2, 2008
  8. mwb1100

    mwb1100 Active Member

    Thanks for the info! That helps me get an idea of what's going on, not that it really matters but I find it interesting nonetheless.

    If James or anyone else has the desire and time to post more, that'll be great.
  9. Peer

    Peer Redfox Development Team Staff Member

    Yep, that's exactly what I'd have answered.
    One might add that also DVD players on PCs will show a differing "robustness".
    That's because not all PC-players use the file system.
  10. Webslinger

    Webslinger Retired Moderator

    8) My answer is peer-approved! :D