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Author Topic: Sega CD / Mega CD assets ripping  (Read 612 times)

cannonp1

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Sega CD / Mega CD assets ripping
« on: May 22, 2018, 05:40:27 pm »
I was wondering if there are any tutorials or videos or tools or anything that would help with ripping/replacing assets from Sega CD games? Things like spirits, FMVs, etc,.

I've been searching for a while and haven't been able to find anything

Jorpho

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Re: Sega CD / Mega CD assets ripping
« Reply #1 on: May 22, 2018, 11:15:31 pm »
There may not be any universal tools available for the Sega CD – meaning every game will store its assets in its own way.

A Google search for "sega cd video compression" (no quotes) turns up a bunch of hits, suggesting that a version of the Cinepak codec was in common use.
https://segaretro.org/Cinepak
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cannonp1

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Re: Sega CD / Mega CD assets ripping
« Reply #2 on: May 23, 2018, 01:47:44 pm »
I've found a lot of material on rom hacking cartage systems but little to no info on Sega CD, has anybody really even attempted it?

ultimaweapon

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Re: Sega CD / Mega CD assets ripping
« Reply #3 on: May 24, 2018, 07:43:54 am »
As far as I know, there's only been a hack of Sonic CD and Final Fight CD, so there probably isn't much out there as far as info and tools, etc. I would love to see a hack of Eternal Champions: Challenge From The Dark Side.
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Jorpho

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Re: Sega CD / Mega CD assets ripping
« Reply #4 on: May 24, 2018, 11:14:46 am »
As far as I know, there's only been a hack of Sonic CD and Final Fight CD, so there probably isn't much out there as far as info and tools, etc.
There's also this translation for Game no Kanzume (i.e. the Phantasy Star II text adventures).
 http://www.romhacking.net/translations/1567/

And there's a version of Sonic Megamix for Sega CD, but that probably doesn't count.

I've found a lot of material on rom hacking cartage systems but little to no info on Sega CD, has anybody really even attempted it?
There are many things in reverse-engineering that are common to all platforms.  I expect you could use Tile Molester to view uncompressed graphical data, for instance.
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GHANMI

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Re: Sega CD / Mega CD assets ripping
« Reply #5 on: May 24, 2018, 11:48:53 pm »
Regarding Sega CD assets, it usually uses the same regular Megadrive graphical formats, so Crystaltile2 on tile mode N64/MD 4BPP should be alright for most ripping and viewing (as long as it uses the proper palette so that colors show correctly... I usually recreate 16 colors by hand but probably should write a converter one of these days).

Compression was a concern for cartridge games but the polar opposite of those practices was in effect for CD based games. Cartridge games would leave anything frequently used (fonts, HUD, player sprites) uncompressed while compressing less frequently used graphics (cutscenes, etc..). Of course exceptions always existed.

The many ways I used to find graphics, but by no means an exhaustive list:

- Uncompressed: much more frequent than what you'd expect.
- Nemesis: graphical compression used for a LOT of first party Sega games, and even third party ones. There's a command line tool that detects and dumps everything using it, and another one (that covers three less frequent compression formats used by Sega) that can compress and decompress as long as you have the offset.
- Run length encoding: it's often obvious enough even in compressed form when viewed in a tile editor
- Rob North Compression: Graphical. Used by European developers and in Sonic 3D. (idk if there's a tool for it here)
- Toshio LZ: Used in Crusader of Centy.
- Konami LZ: 3 revisions. Graphics mainly. A command line tool by Lab 113 is on RHDN's database, as well as another one for the SNES variants.
- Westone LZ: two variants, but one was used a lot. Used in MW3 and MW4.
- A compression type Game Arts used for Lunar and a bunch of other games.

I recommend ripping them off the VPU (VRAM) memory and passing them to a tile editor, using any debugger-capable emulator that allows so. The game needs them uncompressed after all to make use of them at some point.

goldenband

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Re: Sega CD / Mega CD assets ripping
« Reply #6 on: May 25, 2018, 12:46:03 am »
At least one Mega CD game is low-hanging fruit: Cosmic Fantasy Stories. It's trivially easy to implement English text, as the script is uncompressed Shift-JIS, and a fair amount of work has been done already -- see thread here -- it's just that none of us ever followed through with it.

Some work has been done on Shadowrun too, though last I knew they were running into show-stopping bugs.

Otherwise the Sega CD/Mega CD is pretty much the undiscovered country of translation patches. It's the only major system I can think of with a large Japanese-exclusive library and no translation patches to speak of (Game no Kanzume doesn't really count, I don't think, since it's essentially a compilation of games that could've been played on a MegaNet-equipped Mega Drive). Even the 3DO has a translated game, Doctor Hauzer.