List of available Sonic Adventure (+DX) builds

This is a list of all distinct Sonic Adventure (+DX) versions that can be obtained today as far as I know. Originally I wanted to make a branching timeline of SA1 builds, but I couldn’t find a good way to put it on a blog, and I also realized some builds, like the Autodemo, don’t necessarily fit in a single timeline, so here’s a list instead. There is also a lot of information on SA1 development on TCRF, which I recommend if you want a timeline of SA1 development with screenshots and other details.

Dreamcast builds

Let’s start with the original game on the Dreamcast. Note that I’m not including builds that we don’t have, such as the Tokyo Game Show demo and the version used for the Tokyo International Forum unveiling video (assuming the footage comes from a single version of the game).

TitleVersion codeRelease dateDate in IP.BINComments
Sonic Adventure (Autodemo)1.000None1998.10.16Contains a mix of binaries and assets in various states of development. Some stage files were built for an older version of the main executable.
There’s a lot of stuff written already about this version, so I won’t go into details. I should say that I recently got it on an actual disc, and my copy looks different from the scan on Hidden Palace, but maybe it’s just the scanner. I dumped it, and the contents were completely identical to the Hidden Palace version.
Sonic Adventure (Japan)1.0071998.12.231998.12.10The earliest official release of SA1 on the Dreamcast. Japanese language only. Some cutscenes have different camera angles compared to later releases. Some SET objects and camera setups are different in levels. This version has running “motion blur” effect for Sonic and Knuckles and the cowgirl billboard in Casinopolis, which were removed in later releases. This version also has some programming differences, such as collision for the burger shop man and different Lost World spikes behavior.
Sonic Adventure Taikenban1.0021999.??.??1999.03.02Demo version for the Japanese market. Mostly similar to the original JP version. The only version that introduces programming and SET layout changes to make the game easier.
Sonic Adventure – Trial Version for E31.000None1999.06.08A version of the game with an in-progress localization. Contains an early version of the English script and different voice acting. Some character sounds are also unique to this build. The title screen has a completely different design, and the level select menu has difficulty ratings. Starting with this version the running blur effect is missing. Cowgirl is replaced with another billboard starting with this build. Some SET layouts have been updated to reduce Z fighting. Some cutscene camera angles were also updated starting with this version.
The date in IP.BIN is interesting because it’s later than Limited Edition despite being an earlier version of the game. The actual game was likely compiled in spring 1999 (not earlier than March 12, as indicated by the strings present in 1ST_READ.BIN).
Sonic Adventure Limited Edition1.001 and 1.0021999.07.??1999.06.03 and 1999.06.04This version was available in the US for a short time before the final US release. Unlike previous versions, the level list in Trial Mode no longer matches the game’s internal level list. Internet features are replaced with a short demo. The Internet demo is also present (although not accessible normally) in all versions of the game after this one. This build has incomplete localization in languages other than English, and the menu to change the language of messages and voices isn’t functional yet. There are at least two variations of this build, however the only differences are between IP.BIN files, which have different dates, region codes and version IDs.
Sonic Adventure – Trial VersionGenerator Vol. 1: 1.002

Dream On Vol. 2: 1.000
Generator Vol. 1: 1999.09.09

Dream On Vol. 2: 1999.09.30
Generator Vol. 1: 1999.07.08

Dream On Vol. 2:
Demo version based on the US release. Unlike Taikenban, this demo doesn’t play cutscenes except those played after waiting on the title screen.
Sonic Adventure (US)1.0041999.09.091999.08.12First American release. Mostly the same as Limited but with finished support for other languages. From this version onwards the game includes the TV Settings menu to select between 50 and 60 hz modes.
Sonic Adventure (Europe)1.0031999.10.141999.09.09The first version that introduces an animated title screen. Some SET layouts were updated from US 1.004 with minor fixes.
Sonic Adventure International (Japan)1.0031999.10.141999.09.20Mostly the same as the European release. Both Japanese and American SA1 websites can be accessed via the built-in browser.
Sonic Adventure International (Dreamcast Express Extra)1.0011999.??.??1999.11.19Included on the demo disc “Dreamcast Express Extra”. Unlike the other demos, this one comes with an animated title screen. Pressing Start takes you directly to Sonic’s Emerald Coast, which drops you back on the title screen after you beat the stage. Although only Emerald Coast is playable, the game includes all cutscenes and gameplay demos that play after waiting on the title screen, so you can see several Action Stages and Adventure Fields ingame. This demo lacks English HUD and menu textures, so the game will have visual glitches if the console’s language setting is not Japanese.
Sonic Adventure (US) – Sega All Stars version1.0052000.08.221999.10.05Second American release based on European or International.

Gamecube builds

On the Gamecube we have two very interesting prototypes which fueled a lot of SA1/SADX research. Much of the knowledge on the game’s internal workings came from the first Preview prototype years before we got the X360 version with debug symbols. Apart from the prototypes, the builds on this platform haven’t been studied as thoroughly as the Dreamcast version. It is notable that the Gamecube ports have sequenced sound effects, which use a Gamecube adaptation of the MLT file format that was originally introduced in Dreamcast SDKs. Interestingly some character grunts are similar to the ones found in the E3 1999 version of SA1 DC, and some changes to assets are similar to the Autodemo and early prototype screenshots of SA1, but that’s a topic for another post. There is no doubt that SADX code is based on a later version of SA1, most likely 1.005 or International. Also, all versions of SADX have a leftover texture archive with title screen textures from SA International.

TitleRelease dateDate in apploader.imgComments
Sonic Adventure DX – PreviewNone2002.04.10This version appears to be based on SA International and contains work-in-progress “DX” changes. Some features that were disabled in later builds are partially functional in this build. This version has a lot of debug functionality. The original game’s palette lighting system can also be activated in this version, although it doesn’t look correct. The Chao system hasn’t been reworked yet and is mostly functional and similar to SA1 DC. Although other languages are present, the game only works correctly in Japanese. This build has leftover binaries from an even earlier version of the port that hadn’t introduced the “DX” changes yet. Unfortunately we haven’t been able to boot the earlier build due to version differences between the REL files.
Sonic Adventure DX – ReviewNone2002.09.05Most “DX” features and redesigns have been finalized. The Chao system is a work in progress. There is also a Chao debug menu. Languages other than Japanese are functional. Like Preview, this version has leftover binaries from an older version of the port without the “DX” changes.
Sonic Adventure DX (Japan)2003.06.192002.09.05The first official release of SADX on the Gamecube.
Sonic Adventure DX (Europe)2003.06.272002.09.05Although the binaries were recompiled, there are no known differences from the JP release other than default language.
Sonic Adventure DX (US)2003.06.172002.09.05Although the binaries were recompiled, there are no known differences from the JP release other than default language.
Sonic Adventure DX (Gamecube Preview Disc)2003.05.202002.09.05A demo version included on the Gamecube Preview disc. Functions similar to the Trial version on the Dreamcast. This release and the Challenge Version are the only two versions of the game that use colored banners in the character select screen. The Start button is disabled during gameplay. No cutscenes are included, however the intro movie plays after waiting on the title screen. The music loops 3 times before the intro movie plays.
Sonic Adventure DX Challenge Version (Gamecube Interactive Disc Catalog Summer 2003)2003.??.??Catalog ISO:
DX ISO: 2002.09.05
Japanese language only. The title screen has a subtitle that reads “Challenge version”. No cutscenes are included, however the intro movie plays after waiting on the title screen. This version has time restrictions, and the timer counts down instead of up. Otherwise this demo seems similar to the GC Preview Disc version except Sonic’s level is Speed Highway instead of Emerald Coast.

PC builds of Sonic Adventure DX (2004)

There are two distinct “base” versions of SADX PC – the original 2004 port and the “Dreamcast Collection” 2010 port. The 2004 port is where it gets really complicated as there were releases in different countries and the details on the actual differences are fuzzy. There are versions released in the UK, Germany, France, Spain, Italy, Hungary, Sweden, Australia, Israel, Brazil and Singapore, which may have minor differences. I know for sure the EXE in the Hungarian version is different from the “regular” European version. However, I must also say that the differences between these versions are so minor that almost all assets in sonic.exe are placed at the exact same addresses as the US version. One notable exception is the Korean version, which I have included as a separate entry in the table.

All versions of the 2004 port share the same features and downgrades. The 2004 PC port is based on the Gamecube port as it contains strings mentioning REL files. One interesting thing about the 2004 and later ports is that they use the blue water texture in Emerald Coast, which was used in prototypes but replaced with a green one in the final version on the Gamecube. The 2004 version uses WMA files for music and voices unlike the versions before and after it that use ADX. This port also abandons sequenced sound effects and switches to a different soundbank format containing raw PCM WAV files.

Title / CountryRelease dateComments
Trial Version B (Japan)2003.11.21Includes one level for Sonic, Tails and Knuckles. Strings in the EXE indicate it was compiled with Intel(R) C/C++ Compiler Version 4.5 00015. This and Demo A are the only versions where these strings can be seen. Unlike the Gamecube demo, this version doesn’t have colored banners in the character select screen and doesn’t play any cutscenes. The title screen plays a longer version of the main theme (normally heard in the main menu) on repeat.
Trial Version A (Japan)2004.02.??
(before 2004.02.03)
Includes a level for each of the six characters. Other than that it is the same as the B version. It also has the same compiler strings.
Trial Version A (Global)2004.10.02Same as the Japanese demo A but in English. Has the same compiler strings as the Japanese demos.
Japan2003.12.18The earliest full release of SADX PC. Japanese is the default language, but all other languages are also supported. The title screen, the intro and the main menu background are always in Japanese. This version comes with SafeDisc copy protection and hasn’t been researched much.
US2004.09.14This is the version of SADX PC used for research and modding.
Europe (UK)2004.02.06
Mostly the same as the US version except more advanced copy protection. There may be different protections (SafeDisc or SecuROM) in different releases. There was a protection-free re-release in “Sonic PC Collection” in 2009.
Korea2004.07.14A complete Korean localization of SADX PC, including all ingame dialogue, all menus and a colored manual. This version is unique in that it contains different assets translated to Korean, as well as various programming changes related to localization. It is also the only version of the 2004 PC port that has unique FONTDATA0.BIN and related structures in the EXE to support Korean. Voice language is English. Japanese voices are automatically replaced with English voices, although the actual files for Japanese are still included.

The new ports (2010 onwards)

In 2010 SEGA released a bundle for PS3 and X360 called “Dreamcast Collection”, which contains ports of several Dreamcast games including SA1/SADX. Although it is bundled as “Sonic Adventure”, the core game in these ports is based on the 2004 PC version of SADX. However, it does put back the original Dreamcast title screen with ripples. While they share almost all of the downgrades of the original 2004 PC version, for obvious reasons these ports have completely different rendering and sound systems that were developed by SEGA of China. They use shaders for character lighting and switch back to the ADX format for music and voices. Interestingly shaders and textures for water distortion are also included, which suggests that they were going to reintroduce Gamecube water effects, but there is no water distortion ingame. In addition, the soundbank format was revised, and sound effects switched from WAV to ADX.

These ports also introduce many additions wrapped around the original game’s systems, such as a texture replacement hook using DDS textures, support for achievements and online leaderboards, a different main menu system, new screens for credits, controls and tutorials, new fonts etc. Game Gear games are inaccessible (but still technically there), while Mission Mode and Metal Sonic are unlocked via a paid DLC.

This collection was also released on PC twice – in 2011 (physical) and 2016 (Steam). The 2016 version is known as “Dreamcast Collection Remastered”. Little is known about the differences between the 2011 and the 2016 versions, but on the surface they appear to be the same. The version of SADX currently available on Steam is the Remastered version. The Steam version comes with the DLC force enabled, and the Dreamcast title screen is inaccessible. If enabled via hacking, the DC title screen is a static image, although the model for the animated title screen is present in the binary.

These ports are the least researched and for the most part don’t present much interest. However…

X360 prototype builds

In 2020 several development builds of the X360 port were discovered, including a near-final build with debug symbols. The debug symbols have helped a lot in identifying assets and code in the PC version. I’m listing all known builds of the X360 version, including the final one.

Version IDBuild dateComments
362009.12.15The executable in this package is not the actual game, but some kind of X360 leaderboards and DLC test. Interestingly it does include shaders.
462009.12.28Same as above.
792009.12.30Same as above.
1042010.01.08This version is missing some features specific to the 2010 ports that would be implemented later, such as mipmaps (so in this build the game looks pretty much like the 2004 PC port), European language translations of CON_REGULAR_E.PVM and some logo screens before the game starts. The title screen is a static image, and the “Press Start” texture is from the Gamecube version.
This build has a different version of the image used for the 4:3 border.
1352010.01.22This build introduces the animated title screen, more logos and a new “Press Start Button” texture.
This version has a “Face recognizing” password screen which appears to be the developers’ attempt at a joke.
Password: Sonikudamoxi
This version is missing the 4:3 border image.
or 2010.01.30
This version introduces files SOC_FONTDATA0.BIN and SOC_FONTDATA1.BIN, although they are also referenced in Build 135 which doesn’t have them. These files are used for the subtitle font in the final version.
This version has the same 4:3 border as the final version.
Password: Sonikudamoxi
2092010.03.25 or 2010.03.26Introduces automatic mipmap generation and a new font for the file select screen, as well as French, German, Spanish and Italian translations of CON_REGULAR_E.PVM. In all previous versions of the game CON_REGULAR textures were only in English and Japanese.
Password: damoxifL
3872010.08.01No known differences from the final version. However, this build has a leftover “Test” folder that contains a PDB file with debug symbols, which makes it the most important prototype of the whole bunch.
Before this build, all assets that were originally in the DLLs in the 2004 version were compiled into the main executable. From this build onwards they are split from the main binary again.
3902010.??.??Final version.

If you own a rare version of the 2004 port, let me know! The Korean version was a big surprise and very interesting to look at. Maybe there are more unique versions out there?

Sonic Adventure DC-HD first release

Sonic Adventure DC-HD is a new way to play the Dreamcast version of SA1 on the flycast emulator.

You can play SA1 with the following improvements:

  • The game runs at 60 FPS during gameplay without framerate-related glitches (hopefully).
  • Widescreen hack without model clipping or HUD stretching (some HUD stuff is offset though – this will be fixed eventually).
  • All videos can be skipped by pressing Start, not just the intro.
  • Cheat code to disable all cutscenes.
  • If you cannot run in a straight line with your controller/keyboard, there’s an optional patch for that.
  • Less choppy ocean in Emerald Coast (similar to Dreamcast Conversion for SADX PC).

Sonic Adventure DC-HD is distributed as a patcher program which you use on the original GDI of SA1 (US 1.005, animated title screen) to produce a patched version. It also comes with a cheat file that you need to load in flycast if you want to use the widescreen hack. Follow the instructions on the repo for more details.

This project is a work in progress. Not all features are complete and new features may be added in the future.

SA1 DC-HD has been tested on the standalone version of flycast on Windows and Android. The modified image is only meant to be used on the flycast emulator. 60 FPS and the widescreen hack will not work properly on other emulators or real hardware.

A “month without SADX” challenge

I decided to make August an “SADX free” month. This extends over to GitHub, Discord etc. I might fail on the very first day of August or keep it and come back in September, or later, I don’t know. But for now, it’s time for a break. Bye!

Skip All Cutscenes code for Sonic Adventure (Dreamcast)

This is a CodeBreaker code for SA1 US 1.005 that disables all cutscenes. It works exactly the same way as the “Skip All Cutscenes” code in SADX Mod Manager.

010496B4 0900

Cutscenes are removed by nopping the function call that starts the cutscene code, which makes the game assume the cutscene has finished playing. The address of the call is 0x8C0496B4.

There are a couple of small glitches when this code is used. For example at the start of Sonic’s story you can see Sonic in Station Square before the screen fades out and the fight with Chaos starts. This is how it’s actually programmed – the game loads Sonic into Station Square before initializing the cutscene. You can see it briefly when you start Sonic’s story without the code. A similar glitch happens in Station Square in Knuckles’ story.

There are some other potential applications for this code. For example, a conditional code could be made to activate cutscene skip when a certain button combination is pressed, and restore original behavior when it isn’t pressed. That way you could skip individual cutscenes by holding a button when the cutscene is about to play. It could also be made into a simple toggle. Of course it’s not as straightforward as simply pressing a button during the cutscene to skip it, but it’s still pretty good.

SADX Debug Mode version 2.0

Today I’m releasing an update for the Debug Mode mod that adds a free camera mode.

Using the free camera mode

Press Y on the keyboard to enable free camera. When the free camera mode is enabled, you can use the mouse to move the camera around. The control scheme is similar to the one used in 3D editors in SA Tools.

  • Move the mouse to rotate the camera.
  • Hold Left Shift and move the mouse to move the camera.
  • Hold Control and move the mouse up and down to zoom in and out.
  • Press both Left Shift and Control to lock the camera in place. Press them again to unlock it.
  • Press Numpad + and Numpad – to change camera speed.
  • Press Y again to re-enable vanilla camera. It will remain locked in place until the character touches a camera trigger.

I would like to thank Speeps for providing the source code of an unreleased mod with the the original free camera code, which became the basis for the free camera mode in this mod.

Sonic Adventure VMS + Chao Editor first release

Today I’m releasing a new tool based on the original SA1 DLC editor. This tool has the DLC editor integrated, but its functionality expands to cover more VMS files in SA1. Eventually I would like it to support all of the formats described here, but the highlight for today’s release is the inclusion of a new Chao editor.

Like the original DLC tool, the updated editor will be included in SA Tools, which also have a big update underway. While the SA Tools update isn’t ready for release yet, you can download the editor here:
Download (temporary link)
The Chao editor is experimental and will be updated as more information on SA1 Chao data becomes available. There is no documentation for it at the moment, although the most important data should be self explanatory.

The Chao system used in SA1 is the least researched of all Chao games. There are several Chao editors for SADX and SA2, but the only Chao editor for the Dreamcast version of SA1 was Tyro’s VMU editor that requires running on an actual Dreamcast VMU or a VMU emulator, which I found inconvenient. Besides, there have been some updates regarding SA1 Chao data (for example we now have the full SA1 Chao data struct from SADX X360 symbols), and I wanted to make use of that new knowledge to help advance SA1 Chao research. Although several aspects of it are now known better, Tyro’s notes on SA1 Chao data were one of the most important sources of information for developing the editor. I would also like to thank the Chao Island member UltimaNumber, who kindly shared the bits of information I was missing and explained how SA1 Chao data works.

The tool can import all Chao VMS data. Data produced by the Japanese version is also supported:

  • SA1 Chao Garden save file
  • Download Data (Black Market Chao)
  • Chao Adventure (created when you take a Chao out for a walk)
  • Upload Data (created when you hold Y+A as the Chao goes in the transporter)

At the moment saving is only supported for Chao Adventure and Download Data, but you can export selected Chao from the garden save file as Download Data or Chao Adventure data. There’s also an option to export files with headers used by the Japanese version of SA1.

As Chao data is rather complex and the editor is experimental, there may be some bugs, especially with saving data. Also, expect UI changes in the future.

I’d like to thank Speeps for providing a screenshot of Buddy the Chao that I used as an icon for this tool.

Sonic Adventure Black Market Chao

The first Sonic Adventure on the Dreamcast had a Black Market just like the sequel. The archived version of the original website still has the pages and CGI scripts for it, as well as VMU files, which we’re going to look at today.

I didn’t access the Black Market back when it was online, but I’ve heard that the US version never worked because of some bug. The messages from Chao Doctor all the way to January 2000 mention that the Black Market was about to launch, and the comments in the CGI script used on the website suggest it was indeed broken at the time of archival:

The Japanese version was functional though, and it was possible to download several jewel Chao. The Ruby and Emerald Chao didn’t have any emblem requirement. It looks like they were given out “for free” to celebrate the Dreamcast’s US and EU launch anniversaries. However, according to this page, the Emerald Chao was released during an event “Magical Garden: Yume no (‘Dream’) Dreamcast Festival” that took place on March 27, 1999. I can’t find any other information on the event so I’ll have to leave it there for now.

The Amethyst Chao was unlocked when you had 100 emblems. The Sapphire Chao isn’t referenced in the pages or scripts but its VMU data exists. Apparently the US version was going to add a new “NiGHTS” Chao that would also cost 100 emblems. Although the NiGHTS Chao is referred to as “very special Chao”, it’s actually a regular Fly type Chao with animal parts rather than a unique character Chao, which SA1 doesn’t support anyway.

Chao downloads are stored in 8-block VMS files, and Japanese files have a different header although the data is compatible between all versions. There’s a script on the website (likely used for Chao daycare) to generate Chao VMS files, and it alternates between Japanese and US headers, which are stored as binary data on the website. The header is set up like a VMU game header, similar to Chao Adventure. Here are all the files found in the site’s archive:

DescriptionVMI fileScreenshotEmblem requirement
Emerald ChaoCHAO_EME0
Ruby ChaoCHAO_RUB0
Amethyst ChaoCHAO_AME100
Sapphire ChaoCHAO_SUF?
NiGHTS Chao (US only?)KNIGHTS100
Download all of them here

I’ve also made Chao Download data for BUDDY, the developer Chao mentioned in my previous post. Download it here to get it in your copy of SA1 DC.

The SA1 website, including the Black Market, was restored by the DreamPipe team and is now accessible on hardware if you connect through DreamPi or with edited DNS settings. The site is located at

List of VMU filename references in Sonic Adventure

There are a lot of mysteries about Sonic Adventure’s files on the VMU, some of which we’re going to unravel today. I’d like to also use this post to list known VMU filenames in SA1 for future research.

Let’s start with the better known stuff. The main save file is called SONICADV_SYS in the original Japanese release, and SONICADV_INT in all other versions. The newer versions contain text and voice language settings which aren’t available in the original Japanese version. Normally the Japanese version doesn’t load US/EU/International save files, and vice versa. However, the game will recognize the other version’s save file if you rename it.

Now let’s talk about Chao files. The main Chao save is called SONICADV_ALF and is compatible between all regions. When you take a Chao out for a walk using the VMU-shaped transfer machine, the game creates a file called SONICADV__VM on the VMU. This file contains the VMU game Chao Adventure with the Chao’s data written directly into the game file.

The filename SONICADV__VM was also used for Chao downloads from the website. In the Japanese version of the game you could download rare Chao (Sapphire, Ruby, Emerald) from the website if your main save file had a certain number of emblems. These are discussed in a separate post.

Upload Data

There’s also a bunch of files that are created on the VMU at certain points in the game. These files were meant to be uploaded to the official website using the game’s built-in web browser. Among such files were Chao, level clear times and results of DLC challenges. They contain an HTML page with a hidden field that contains encrypted data encoded as a Base64 string. The encryption is the same between these files and DLCs.

The Japanese version had different strings for the webpage so the embedded HTML is different from later revisions, also the Japanese version uses different filenames. Here are all of them:

Filename (JP)Filename (US/EU/INT)DescriptionHow to create
SONICADV_H00SONICADV_H07Chao Upload dataHold Y+A when a Chao is going into the transporter until you hear the ring sound
SONICADV_H01SONICADV_H04World Ranking DataHold Y+A on the file select screen until you hear the ring sound
SONICADV_H02SONICADV_H05Twinkle Circuit DataCreated automatically when you finish the DLC Twinkle Circuit course
SONICADV_H03SONICADV_H06Event Result DataCreated automatically when you finish a DLC challenge

Hidden Chao on SA1 US GD-ROM

Interestingly there are files SONICADV_H00.BIN and SONICADV_H04.BIN in the root folder of SA1 US GD-ROM. These appear to be earlier versions of the data produced normally by newer revisions of the game. Apart from using the Japanese version’s naming scheme they have some differences in HTML compared to the regular files. While it isn’t compatible with either version of the game, the interesting part is the actual data stored in these files.

The Chao file contains a baby Chao called ♥BUDDY♥ that was submitted by Yep, there’s been a Chao hidden on the game’s disc all these years. Here’s what it looks like:

Stats: Swim: 19 Run: 17 Fly: 17 Power: 27 HP: 13 Max HP: 17

Eventually you’ll be able to edit Chao upload and download data, including this file, as well as the main Chao save. I just need to get to writing a Chao editor for SA Tools.

Character Voice Packs

When one of these files is placed on the VMU, the game changes the character voicing the menu screens. The files themselves don’t have any meaningful data other than an icon, a description and a single string Team Andromeda. The game seems to set the voice mode based on the filename. Again, the Japanese version looks for different filenames, so there were actually 18 unique files for voice packs! Do we even have their Japanese versions archived?

Filename (JP)Filename (US/EU/INT)Description
SONICADV_V03SONICADV_V13Knuckles’ voice
SONICADV_V07SONICADV_V17Dr. Eggman’s voice

Events and Challenges

A lot has been written about SA1 DLCs, and they are now fairly well understood, up to the point that you can make your own DLCs that will work on an actual Dreamcast without hacking the base game. So here I’m going to talk about things that are a but more obscure.

One major limitation of the DLC system in SA1 is that you can only have one custom model. While I haven’t been able to get the game to load more models, I got it to load a model that isn’t stored in the DLC file by editing the pointer in the DLC file’s model binary to make it point to a different location in memory. It’s still just one model per DLC and you have to supply its textures separately but at least you can load stuff outside of the DLC file if you really want to. Maybe it’s possible to add more pointers and make the game load them somehow? I’ll look into that sometime soon.

The filenames for the DLCs are SONICADV_aaa, where aaa is a number from 000 to 999. IDs from 000 to 200 are reserved for DLCs that only have text in Japanese. Early events released in Japan (Famitsu challenge, QUO challenge etc.) only contain Japanese message strings, and their string table is smaller compared to later events that had text in other languages. However, these old events still work with newer versions of SA1 with Japanese text displayed correctly regardless of the game’s language setting. The game doesn’t load strings for other languages if the DLC ID is lower than 200. This is why there is a gap between Japanese and international event filenames: the last Japan-exclusive event was called SONICADV_003 and the first international event was called SONICADV_501 (though SONICADV_200 would’ve worked too).

The Weird Stuff

The game’s main binary has several filename strings that suggests some interesting functionality. Earlier this year we learned from Exant’s fascinating discovery that we can still activate the game’s built-in lighting editor that looks like this:


Apparently this editor can load lighting files from the VMU, and that functionality seems to be still in the game, we just need to learn how to activate it. The palette file is supposed to be called SONICADV_P00, and the SL file is SONICADV_S00 (in the Autodemo they’re just PL_ and SL_). It’s possible that numbers other than 00 were also used. There is a function loading these files at 0x8C011D46 (US 1.005). It also seems like LANTERN_PALETTE and LANTERN_SOURCE were VMS titles, while LANTERN/パレット情報 and LANTERN/環境情報 were VMS file descriptions. I’ll experiment with custom VMS files to see if the game picks them up.

There are also some strings suggesting there was VMU to PC transfer at some point. The filenames used in that transfer were SONICADV.VMS and SONICADV.DL0. Doesn’t look like it’s used, but who knows, maybe we’ll recover it eventually.

Sonic Adventure patches (Better 60 FPS + drift fix)

If you’re interested in hacking Sonic Adventure, you’ve probably seen 60 FPS and widescreen codes for the Dreamcast version floating around. The problem with 60 FPS codes for SA1 is that they make cutscenes run at double speed. Here’s my understanding of why it happens and a solution for version 1.005 (US, animated title screen).

The game uses two values to control framerate and speed: the frame increment (8C754EBC) and the multiplier (8C754EC4) used in physics and other things. The frame increment controls the actual framerate (1 for 60 FPS, 2 for 30 FPS), and the multiplier speeds up or slows down the physics to match it (1 is original speed). The Dreamcast version runs at 30 FPS everywhere except menus and Twinkle Circuit. In 30 FPS mode the frame increment is set to 2, and the multiplier is also set to 2 to speed up the physics to match the reduced framerate. In menus and Twinkle Circuit both values are set to 1, so the game runs at its original speed at full framerate.

This would be all fine, but the problem is the cutscenes. They are programmed in double speed, so the game sets the frame increment to 2 and leaves the multiplier at 1 to get them to work at half speed. This is also the real reason SADX cutscenes are still capped at 30 FPS – updating them would require fixing the timings in all functions used by cutscenes to work properly at 60 FPS, which is a lot more work than simply unlocking the 60 FPS mode in levels like the developers did.

The problem with existing codes is that they don’t account for the above and simply force both values to 1, which causes cutscenes to run at double speed. To fix this, instead of changing the values directly we can do the same thing SADX developers did, and change them depending on what happens in the game. Like in SADX, there is a function that is called to set the required frame increment and multiplier. All we have to do is patch the arguments that are passed for this function when the game loads levels, and leave cutscenes alone. Here are the addresses for version 1.005 (US, animated title screen). Just change the bytes at these addresses from 2 to 1, and the game will set framerate modes like SADX. If you use Demul with Cheat Engine, replace the starting 8C with 2C.


Here’s also a code that you can add as a custom cheat for redream. It’s a regular CodeBreaker code so you could use it on other emulators or on real hardware.

cheat=0204956E 420BE501 0204E662 4F22E501 02054736 430BE501 02082AAE 420BE501 0209A1D2 D252E501

There are still two problems remaining with the 60 FPS code:

  • The hardware cannot handle the game at 60 FPS most of the time (sometimes it struggles even at 30 FPS), so you will get a slow motion effect like in older SA1 preview videos. Unfortunately this also affects emulators – for example, at the moment the game does not reach full framerate in redream. There was a similar problem with Sonic Colors, which the Wii can’t handle at 60 FPS, but that was resolved with Dolphin’s overclock feature. Maybe we’ll get that in Dreamcast emulators someday?
    UPDATE: It seems to be perfect on flycast, no slowdown at all.
  • There are glitches that happen when the game runs at 60 FPS. It’s possible that some things in the game were added after the decision to switch to 30 FPS was made, and perhaps they were only tested at 30 FPS. A lot of such glitches appear in SADX. For example, the Leon badnik almost never attacks the player and disappears too fast. There are visual glitches too, for example Tails’ tails are too fast, and the background in the tornado section in Windy Valley loses the multi-layered effect for one layer. A lot of these glitches are fixed in the Dreamcast Conversion mod for the PC version, and it’s also possible to fix them in the Dreamcast version if we really want it. Interestingly some issues that affected DX at 60 FPS don’t affect SA1 at 60 FPS – for example, the Egg Hornet engine sound glitch.

There’s another issue with SA1 on emulators related to not being able to run in a straight line with the keyboard and some controllers. You can fix this by disabling analog interpolation by writing 00 00 00 00 to 8C051278 and 8C051430. CodeBreaker code:

02051278 00000000 02051430 00000000

It’s not an ideal solution but that will do for now. A better fix may show up very soon.

Sonic Adventure DLC tool: GUI version released

I’ve updated the SA Tools with a new version of the SA1 DLC tool that lets you create and edit VMS files for SA1 on the Dreamcast.

Some documentation is available here.

Apart from the GUI making it easier to edit things, this version also fixes several issues with the original tool that made it produce incorrectly aligned VMS files. Now it should be possible to modify and rebuild any of the official DLCs, or create completely new DLCs from scratch.

The tool ended up being a bit more complex than I originally anticipated, and testing it was a challenge. I’d appreciate it if you try it out and let me know on x-hax if you run into any issues. Have fun!