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CHD usage increasing #113009 03/30/18 09:19 PM
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Shoegazer Offline OP
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Hello, with forum threads like this it seems CHD use is on the rise. That's a really nice boost to the format's visibility and it more broadly establishes how versatile and useful it really is. I wonder though, with more people converting to CHD, aren't some historically-significant artifacts in danger of getting lost over time? For example, since chdman doesn't yet support subchannel data, as people convert and delete this data with older formats, won't it become increasingly scarce?

Re: CHD usage increasing [Re: Shoegazer] #113010 03/30/18 10:49 PM
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R. Belmont Online Content
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CHDMAN does support subchannel data if you import a CDRDAO (bin/toc) image. There is no way to express that data in the far more common CDRWin (bin/cue) format, so for stuff imported from that format its already gone.

We would like to support the add-on PS1 protection data (.esomething?) that people use eventually though.

Re: CHD usage increasing [Re: Shoegazer] #113011 03/31/18 02:41 AM
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Shoegazer Offline OP
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Interesting, I didn't know support was already there. That's good. Are you thinking of the ccd/img/sub format PS1 could use? I'm not not aware of anything with .e but there's a ton of formats out there.

Speaking of PS1, this issue has apparently been fixed in post-0.175 chdman, but as Pixelnarium said in the last post of the thread, some software lists like PS1 still have older hashes which might cause people to use an older chdman just to get a match, possibly losing important data in the process. I'm sure it's low likelihood but maybe more possible with greater chd visibility now. There's probably a huge challenge in updating large hash lists against public reaction but maybe such things could be phased in gradually.

Re: CHD usage increasing [Re: Shoegazer] #113012 03/31/18 04:05 AM
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The PS1 software list also seems to only have about 10% of the games in the list anyway, notably the almost complete lack of non-US releases, if I am looking in the right place (/hash/psx.xml, which is 3.4MB). Case in point, search for cricket and there should be 5 dumps according to redump.org (all of which are PAL-only releases, of course).

Re: CHD usage increasing [Re: Shoegazer] #113014 03/31/18 10:12 AM
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Fake Shemp Offline
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I was planning on going over the psx softlist after I finish the dc list. So it will get done sometime at least.

Originally Posted by R. Belmont

We would like to support the add-on PS1 protection data (.esomething?) that people use eventually though.

SBI data like redump use?

Last edited by Fake Shemp; 03/31/18 10:16 AM.
Re: CHD usage increasing [Re: Shoegazer] #113017 03/31/18 02:12 PM
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I thought it was .EBP or something like that. It's whatever other emulators accept.

Re: CHD usage increasing [Re: Shoegazer] #113019 03/31/18 02:27 PM
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nah, it's sbi, which as far as I know is some kind of very specific piece of subdata? I guess you could technically convert it into a real subchannel, or have chdman import it as such into an existing CHD?

since other emulators support it I think it's safe to assume it's documented anyway, would just be a case of making sure all of them are applied to the right images, some of the copy protections are very subtle (games using wrong ingame parameters after a few levels etc.)

Re: CHD usage increasing [Re: Shoegazer] #113020 03/31/18 07:13 PM
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As I understand it, sbi is just a portion of subchannel data and the position they're located. The few copy protections that use illegal subchannel data just have it at some spots, so only that relevant data is stored. It makes some sense to do it that way since subdata is so hard to dump without errors.

Last edited by Fake Shemp; 03/31/18 07:14 PM.
Re: CHD usage increasing [Re: Fake Shemp] #113044 04/02/18 07:29 PM
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remax Offline
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Originally Posted by Fake Shemp
As I understand it, sbi is just a portion of subchannel data and the position they're located. The few copy protections that use illegal subchannel data just have it at some spots, so only that relevant data is stored. It makes some sense to do it that way since subdata is so hard to dump without errors.


Yes, it's exactly that (i investigated in SBI a few years ago).

Last edited by remax; 04/02/18 07:30 PM.

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