Question, any way to verify ReDumps in CHD or RVZ format?

[Fugus]

I know this isn't the ReDump forums but figure it's worth the time to ask.

Is there a way to verify ReDump collections in RVZ or CHD format?

I mean both of those are lossless and honestly can't see why ReDump hasn't transitioned to them to begin with. And you can actually run the games while in those formats and while you have to convert them to burn them that gets redundant when they match or beat the files in Bin/Cue or ISO format 7-zipped.

Examples:

7-zip settings: Level Ultra / Method LZMA2 / Dictionary 192MB / Word Size 273
RVZ settings: Block Size 128KiB / Compression Zstandard (recommended) / Compression Level 5 / Preserve Junk Data

Gamecube (682 files)

ISO 927GB (Usable but huge)
7z 672GB (255GB smaller but completely unusable unless decompressed)
rvz 524GB (403GB smaller but completely usable for emulation and can be extracted to burn)

Playstation (2000 files)
Bin/Cue 890GB (Usable but huge)
7z 510GB (380GB smaller but completely unusable unless decompressed)
CHD 510GB (380GB smaller but completely usable for emulation and can be extracted to burn)

I can understand them taking their time due to the number of games involved and how meticulous they are in maintaining a proper set, but what is stopping them entirely for this?

Tried to ask on the ClrMamePro forums if it would be possible for them to support RVZ and CHD as compression formats similar to Zip,7z, and Rar for sets that don't explicitly have CHD files in them but been trying to register an account for them for days and I never get the email to confirm my registration.

Is there any way around this? I have found an app that allows to check some but requires you extract every file to check the extracted thing and then delete it afterwards which seems excessive and can thrash a hard drive.

Edit: And to add in Nintendo Wii (1,376 files)

ISO 5.92TB (Usable but huge)
Zip 5.78GB (Slightly smaller but unusable unless decompressed)
RVZ 2.01TB (Massively smaller and usable for emulation).

Just doesn't logically make sense to use the larger format except if they just want to stick to legacy formats. But if these are able to decompress to those old formats losslessly anyways, just don't see a reason to keep them them for the base auditing. At this point, all they need as a CD Emulator that support CHD and even the PC ReDump would be superior for it.

Actually have an 18TB external I am wanting to use to keep all the stuff backed up but needlessly wastes lots of space on the older format when the newer one allows for much greater storage and usability.

Sorry if I am coming off as mean or anything like that, it is not my intent, I just am wondering why they use these older formats? Also, the ClrMamePro forum is surprisingly hard to register for, tried to register on 4 different emails from 2 different providers and none of them have received the confirmation emails.

[Hiccup]

You can find unofficial RVZ dats for GameCube and Wii - they are kept in sync with the redump dats. Don't know about other systems/CHD, but possibly RomVault can read CHD files as archives, i.e. it scans the files within - worth checking out I think.

[Fugus]

Thank you, I finally got an email to verify an account for ClrMamePro too, suggested them add in the ability to read CHD and RVZ as archives there. Here is to hoping.

Once again, much appreciated.

[2i30817]

I've been thinking of adding something like this for chd in my rhdndat-rn tool.

The way you can do this sanely is to use the algorithm that exists in the gnu zip library I forget the name (and some other places) that can 'join up' crcs into a total crc given the track crc32 and the length in bytes of the track and some other crc settings (that is, without having to have the tracks themselves). Thats why redump game pages have a 'total' crc32 checksum, it's calculated by the site.

Then it's easy, iterate over the tracks info in the dat, calculate the crc, then iterate over the chd iso data (it doesn't have crc32 of the data, just sha256 I think), calculate the crc, memorize it if you can, and compare.

I already do something similar for rvz, only I didn't have to bother with this. Because gamecube\wii dumps don't have multiple tracks.

Only problem is that some no-intro unofficial disc dats, like the unofficial decrypted psp one, differ from redump standard of 'one iso per 'game' entry'. For instance, legend of heroes trails in the sky 1 English there has two isos in a single 'game' entry (as a rom, which is what redump uses for tracks).

This irks me because there are valid usecases for multiple tracks in iso format (for instance, I think some Dreamcast dumps are like this) so I don't have a good idea to blacklist bogus 'total crcs' like this if the redump convention of one disc per <game> isn't followed.