Dreamcast Image Builder

Dreamcast Image Builder is a program that builds modified GDI or CDI images of Dreamcast games using patches (mods).

The mods for the Dreamcast Image Builder are different from the mods used for the SADX and SA2 Mod Loaders and are not cross compatible.

The user interface of this tool is inspired by and built to resemble MainMemory's mod managers for Sonic games.

Prerequisites

Windows 10 or later (x64). Windows 7 and 8.1 may or may not work.
.NET 8.0 Windows Desktop runtime (x64).
GDI dump of the game you want to modify. TOSEC dumps are recommended. Redump CUE may work. CDI or CHD won't work.
(Optional) A Dreamcast emulator such as flycast.

Download

Download the latest version of Dreamcast Image Builder

Mods for the Dreamcast Image Builder can be found on the x-hax Dreamcast Mods repo.

Using the Dreamcast Image Builder

How to Add Games

How to Add Mods

Modding Sonic Adventure

Modding Games (general guide)

Creating Mods

How the Dreamcast Image Builder Works

Dreamcast Image Builder uses community tools to extract and rebuild GDI images for Dreamcast games.

The game's original image in the input folder is extracted to a working "data" folder in the output folder, then the tool applies the selected patches (mods) and builds a new image in the output folder.

Built-in Games

Support for the following games is built-in:

Sonic Adventure (US, 1.005)
Sonic Adventure Autodemo
Sonic Adventure 2 (US, 1.008)
Rez (JP 1.003)
Rez (EU 1.003)
Rez (build 836 prototype)

Support for more games can be added manually or in the UI. See the Adding Games page if you would like to develop or use mods for other games.

User Interface

The user interface of Dreamcast Image Builder is heavily inspired by MainMemory's mod managers familiar to anyone who has modded Sonic Adventure DX, Sonic Adventure 2, Sonic R etc.

Tabs

Dreamcast Image Builder uses a Tab Control with the following tabs:

Mods tab

Use this tab to select and rearrange mods. The arrow buttons on the top right can be used to move the selected mod up or down, or to the top or the bottom of the list. The order of mods in the list affects the order in which they are applied.

There are built-in mods that you can try, but you can also add mods or make your own.

Notes

To add new mods, create the mods folder in the same location as DreamcastImageBuilder.exe and put your downloaded mods there.
Each mod must come in a separate subfolder. Do not extract mods directly to the mods folder.
For mods that have configuration (submods), a ... button will appear under the mod sort buttons. Click it to toggle individual settings in the mod.

Codes tab

This tab lets you select which codes are enabled automatically when the emulator is launched. Some codes in this list are checked automatically if the enabled mods require them.

Notes

This tab only appears for games which have the codes file defined (see Adding Games).
The codes file and associated features are only available for the flycast emulator. The cheat file is in the RetroArch .cht format.

Games tab

This tab lets you select the game to mod and set the input and output paths for it. Input and output paths are saved independently for each game. You can also add, edit or remove game configurations using the buttons on the right. See Adding Games for more information on game data.

Notes

Input path (path to the original GDI/CUE) must be the folder where the GDI file is located.
The input path must contain only one GDI/CUE file.
Only TOSEC GDI and Redump CUE dumps are compatible for input. CDI, MDF/MDS and ISO files won't work.
Input and output paths cannot be the same
Demul, redream and flycast are supported.

Options tab

This tab lets you locate Dreamcast emulators to run the modified images, as well as customize various advanced options.

Build Settings

Default Output Folder sets the default path used when you add a new game. You can check the checkbox below to append the game name to the default output path automatically so that you can have multiple games in the same output folder.

Pause before Build lets you make final changes to game data or IP.BIN manually before the program builds the modified image.

Reuse Original Data Folder makes the program keep the extracted original game data in the data_orig folder and reuse it for later builds. This speeds up the speed of subsequent builds. Although this is not recommended, you can also edit the game data in the data_orig folder to make permanent changes to the game (note that your changes will be deleted if you uncheck this checkbox).

Keep Working Data Folder makes the program keep the modified game data in the data folder. You can inspect this data to check if your mods were applied correctly. Note that this folder will be deleted and recreated on every build.

Emulator Settings

You can configure two different emulators and switch between them using the radio buttons.

Default Binhack Settings

This is an experimental section where you can change default settings for the IP.BIN hack that descrambles the startup binary and resets the GDROM. The settings here are only applicable for CDI.

Binhack offset in IP.BIN configures the offset in IP.BIN where the descrambling code will be injected.

Buffer location in RAM sets the location used as a temporary buffer by the descrambling code.

Region Hack makes changes to IP.BIN so that the game can boot regardless of the Dreamcast's region.

VGA Flag sets the VGA compatibility flag in IP.BIN. In many games that aren't compatible with VGA by default, this is enough to enable VGA support. You may need additional hacks depending on the game.

Auto LBA Hack replaces the boot binary's default GDROM Boot LBA value (45166) with the calculated Boot LBA value (e.g. for Boot LBA 11702 it will write 11868). The default value is found 8 bytes before the CD001 string in 1ST_READ.BIN. Note that the game may perform LBA checks in other places so this option alone may or may not be sufficient to get the game to boot in CDI mode.

Hack Common GDROM Protections is an experimental option that scans the game's main binary for patterns of common protections in commercial Dreamcast games and alters them to remove these protections. This makes many games bootable on CDIs without additional CDI patches as long as the Boot LBA is taken care of. This hack can have unwanted side effects, for example it can corrupt game data if it has byte patterns matching those of GDROM protections.

Update Settings

Here you can check whether you have the latest version of the Dreamcast Image Builder, and enable or disable the update check on startup.

Build Image tab

The Build Image tab displays the build progress, including extraction of the original files, preparation of the data folder, installation of mods and patches and building the final modified image.

Bottom controls

The buttons at the bottom do the following:

Reload: Clear and refresh the mod list by re-reading all mod data.

Save: Save program settings, including all individual game configurations and paths.

Run: Run the Dreamcast emulator (if specified) and boot the modified image.

Stop: Terminate the build process and/or the Dreamcast emulator.

Build: Create a modified image with the selected mods.

Build & Run: Create a modified image with the selected mods and boot it in the Dreamcast emulator.

The CDI checkbox determines whether the program will build a CDI file. If the checkbox is unchecked, the program will build a GDI file.

Notes

CDI files can be burned to CDs (as long as their data size allows) and played on hardware and emulators, while GDI files can only be loaded on emulators and GDEMU.
Making bootable CDI files may require additional game-specific hacks.
If the CDI checkbox is greyed out, it means CDI support is not implemented for the selected game. See Adding Games on how to add CDI support.

Limitations

Dreamcast Image Builder relies on several community tools and shares limitations with them. Among such limitations are the following:

For input, only TOSEC GDI and Redump CUE dumps are compatible. CDI, MDF/MDS and ISO files are not supported.
Additional data in the game INI file may be required to build CDIs. See Adding Games for more information.
Burned CDIs only boot if their Boot LBA is 11702. CDIs built with other Boot LBA may work only on emulators and GDEMU.
CDDA is not supported in CDI mode.
Codes (cheats) are only available for the flycast emulator. The cheat table must be in RetroArch .cht format.