Best way to check gd-rom integrity for bad sectors?

Discussion in 'Sega Dreamcast Development and Research' started by demilich, Oct 24, 2017.

  1. demilich

    demilich Spirited Member

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    Anybody know the best way of checking whether a original dreamcast gd-rom has any bad sectors?
    I'm guessing it would be a way to rip original gd-roms to check?
     
  2. -=FamilyGuy=-

    -=FamilyGuy=- Site Supporter 2049

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    Pretty much dumping it yes. Ideally multiple times over. And verify all dunks are identical. If it's a retail game, you can compare your checksums to the Dumpcast database.

    The easier/cheaper ready to dump a he is probably using the SD card adapter and dcsdrip or dreamshell. @Helder sells (or used to sell?) a mean internal SD adapter, *shameless publicity*.
     
  3. Braintrash

    Braintrash Peppy Member

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    From my dumping experience, if the GD-ROM has bad sectors, SDRip will tell you and stop.

    Funny thing: the game can play without any issue (played it from start to end with all possible modes, since I love this game), but any ripping with SDRip will show what sectors can't be read and stop. No matter how many tries, always the same sectors.

    I also tried to have the disc fixed with these optical repairing machines. Disc was looking pristine after that, but same error at the same sector. (And I also learned many of these machines don't work with blu-ray; basically, they destroy it, something to check before doing optical repairs.)

    So, I guess SD ripping is a good way to start. I used an external SD adapter, bought cheap from China, but without the need to modify the console, and have dumped many games, since I use a dedicated DC for that; worked great. Either external or internal, SD rip is mature enough to be used.
     
  4. yzb37859365

    yzb37859365 Spirited Member

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    what gameļ¼Ÿ
     
  5. -=FamilyGuy=-

    -=FamilyGuy=- Site Supporter 2049

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    Using dreamshell's dumper, there's an option to skip bad sectors and carry on dumping.
     
  6. Braintrash

    Braintrash Peppy Member

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    Yes, but I dump for preservation. As soon as it have one bad sector, the disc is not suitable anymore for preservation.

    Would it be something rare (prototype, no existing dump, unknown revision, etc.), yeah, I would carry on, of course, in order to still have something, maybe fixable even, maybe working as it even if not perfect for preservation. But for a commercial game where we just confirm previous dumps and check for any previously unknown revision, I don't care to carry on the dump, good ISOs already exist.
     
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  7. -=FamilyGuy=-

    -=FamilyGuy=- Site Supporter 2049

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    I had betas in mind. Of course for a commercial game your completely right.
     
  8. Braintrash

    Braintrash Peppy Member

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    Let's hope we don't get (too much) betas with bad sectors. Always heartbreaking.
     
  9. -=FamilyGuy=-

    -=FamilyGuy=- Site Supporter 2049

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    Sadly, it's bound to happen more and more. Unless we found all the betas already, which isn't a merrier thought.
     
  10. S4pph4rad

    S4pph4rad Site Supporter 2015

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    I wouldn't bother with this. When I got GDEmu several years ago, I dumped every single one of my discs. All of them were good dumps because I've kept the discs in good condition (no errors during the process, and I've played through some of them) but most of them don't actually match the checksums found in the dump databases. I didn't bother to figure out why, but I'm sure there could be a number of reasons such as settings and tools used.
     
  11. -=FamilyGuy=-

    -=FamilyGuy=- Site Supporter 2049

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    Summoning @darcagn for this one.

    All my dumps made using a Dreamcast, and I think those made using a PC drive too, matched the Dumpcast or were used to verify unconfirmed dumps. Some tools, like dcpprip added some fixed amount of zeros to audio tracks, but pruning them made the dumps match.

    You should post your dumps hashes so others can compared theirs too, maybe there are different versions/masterings of the same game. It's also not impossible that your GD drive has issues. Trying to dump with multiple Dreamcasts could verify this.

    In any case, multiple dumps with multiple Dreamcasts/GD-Drives is a good idea for unique discs, like betas, for preservation purposes.
     
  12. Braintrash

    Braintrash Peppy Member

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    Yes, we need to know how you dumped them. Not all methods are good and the problem may not be Dumpcast, but your dumping way.
     
  13. darcagn

    darcagn Site Supporter 2013, Site Supporter 2014

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    Hi there, I'm one of the founding guys at Dumpcast.

    Assuming we are talking about U.S. games, if the data track checksums don't match, it is very, very likely that something is wrong with your dump. While your ripping software usually will give an error if the disc cannot be read, it is not out of the ordinary for a dump to be dumped with bad data. We have verified all known data variants for U.S. region retail games and are pretty much complete for Europe too. The only other possibility is that you have some super rare version of a game.

    If the audio tracks don't match, this is pretty normal. Discs pressed in multiple batches across multiple manufacturing facilities have different audio offsets, so in this case you just have a different batch of the same information.

    If you truly suspect that you have a unique disc that is dumped properly, post on our Dumpcast message board, which has a dump hash submission section. We can then attempt to verify it with known hashes and if it is a match it can be entered into our verified database. Or we could figure out if you have a corrupted dump.
     
  14. demilich

    demilich Spirited Member

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    Thanks for all the info guys!
    The main reason I wanted to dump/rip my games is because I want to make sure that the game works from start to finish without me playing the whole game. My physical dreamcast game collection has been growing but I don't always have the time right away to finish a game from start to finish within a few days. It usually takes me months sometimes a year till I fully play a game. So I just to figure out a method of quickly verifying that the gd-rom disc is in good condition.
    As a side note, I remember back in the day when I had some ps1 games that would play good up until a certain point of the game where it would freeze. I reloaded my saved game, even started from the beginning only to find that it would freeze at the same spot. The disc definitely had scratches, but this was maybe 10 years ago before I new any of these forums/info existed.
     
  15. S4pph4rad

    S4pph4rad Site Supporter 2015

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    Never mind, false alarm. My dumps match your database. I had verified against some other list that I found online a few years back, and it didn't match those. But I think that list was MD5. All of my dumps were made with httpd-ack.

    I verified about 10 discs randomly and they all match. I'm still positive all of my dumps are good without actually validating them all, I've never had a single problem with any of them and my original discs are in good condition.

    Sorry for the bad suggestion earlier.
     
  16. -=FamilyGuy=-

    -=FamilyGuy=- Site Supporter 2049

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    Just to point out that this is not a good assumption. Good looking discs and successful dumps that do work might still have some erroneous data. From a preservation standpoint, "I know my dump is good" isn't sufficient.

    That said, to play on your GDEmu, it's totally fine.
     
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