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Understanding Dreamcast .GDI


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Hello All,

I'm back to pick your brains.

I recently retrieved a pack of Dreamcast games. The pack that I have comes as .zips. 

Those archives have some games that are just very large .gdi's (looks like complete disk images) and others that are 1KB .gdi with large .bin and .raw files.

The ones that are .gdi/.bin/.raw I am having no problem turning into .chd's so that they are cleaner and compressed.  They also run without issue in Flycast.  Their resulting .chd's also run fine in Flycast.

The ones that are ONLY one large .gdi are not running in flycast AND are not able to be compressed into .chd's.

I'm sure someone out there has dealt with this before.  Just not sure what I need to do to these large .GDI files to convert them into something useable by the CHDman converter and playable by Flycast.

Thanks,

CH

Edit: I understand, now, that the small .gdi's are essentially just .cue files as I understand them for other games/emulators.  So, it looks like I have a pack that has cue files with the necessary .bins and .raw (music) files and then other games that are just one large disc image as .gdi's.  I'm assuming that there are utilities out there that would allow me to turn my disc images into the "cue"/bin/raw's that I need.  Will hunt for that...

Edited by demosthenes2010
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In case it helps anyone... in further review of the single large .gdi files, I see that they are each the size of a CD (less than 750 megs each) and so likely are just the compressed versions designed for writing to CD. I'd assume that if they were true original .GDI's that they'd be closer to a gig in size.
 
In conclusion, my thought is that I have a mixed set -
Some of the games are the .gdi (cue-esque) file, BIN, RAW files
and
Some of the games are old compressed images for writing to CD. Not sure they will be useful to me and so I'm going to go hunting for another set.

I live on an island in Lake Erie with abysmal internet so if anyone reads this and can fill me in on a solution, please speak up so I don't spend a week getting another set.
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I've created CHD's from Dreamcast GDI images, with no issue. 

CDI images will not be playable in CHD format, because they are already compressed.  I just used those as is. 

I use both redream and flycast depending on the game.

 

 

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3 hours ago, Ateb said:

I've created CHD's from Dreamcast GDI images, with no issue. 

CDI images will not be playable in CHD format, because they are already compressed.  I just used those as is. 

I use both redream and flycast depending on the game.

 

 

I found the same thing. 
I convert all to CHD to use with Flycast. The quality of cdi images isn’t consistent, I found some that work, some just don’t. Even though it sucks, even with a slow connection, I’ve bit the bullet and looked for GDI format which all have converted without issue.

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Figured it out.

The LARGE .gdi files were in fact .cdi's.  They appear to be old rips shrunken to 700MB for the days when people were burning GD-Rom games to CDs.  I've heard that there is some loss in this process.  Will look into how bad that loss might be now to see if I want to keep them or not.  Not sure which emulator was playing these files with the .gdi file extension when they were in .cdi format given what seems to be the pervasiveness of the .cdi file format AS a .cdi rip and the .gdi format AS the cue file, but I haven't been at this long so maybe it is an old standard way of doing it or there is an emulator that accepts them this way.

Anyway, if you rename the file extension from .gdi to .cdi, they will play in flycast.

So, for future people who might see this thread - 

Small .gdi files with bins and raws can be converted to CHDs using chdman.

Single large .gdi files (around 700-750 megs in size) are likely old rips that have been stripped of some data to fit onto standard CDs instead of the larger GD-ROMs.  Someone may have renamed them to the .gdi file format but simply renaming them to be .cdi's again allows them to run in Flycast.

Edited by demosthenes2010
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This post is one of the ones decrying the quality of .cdi's but there are comments further down that say the quality of the rip depends on the skill of the ripper.  At this point, I'm going to lazily deal with it and if I notice especially bad quality, I'll grab new copies of specific games... 

http://www.racketboy.com/retro/faq-how-are-ripped-dreamcast-backups

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