Origins of Sonic Music Hacking

saxman · Feb 5, 2023

I was a little hesitant about making a thread on this, because it's sort of self-serving in some respects. However, anyone who has been following my efforts over the past several months will know about my archiving efforts. I've taken a deep dive into the history on Sonic ROM research. My roots are in ROM hacking and having some of the earliest hacking documentation, but things have come a long way since I was really intimately involved with that. And as with all things, the passage of time tends to create a fog for oldbies and newbies alike -- oldbies in the respect that they have trouble remembering some things or even finding them; newbies in the respect that they don't know a whole lot about the history. There were many people who played major roles that ultimately helped get us where we are today.

I'm making this thread about music hacking specifically, because it's an area that I have deep interest both inside and outside of Sonic. It also took a long time for music modifications in ROMs to become a regular occurrence. In the spirit of continuing my archiving and historical documentation efforts -- and since this is a subject that interests me and was also deeply involved with -- I thought I would put together a ZIP archive of all my music hacks I did while researching the music (along with some from others that came immediately following Sonic QX), my early hacking notes on the subject, and an explanation of how I went from not touching it a whole lot to doing a full exploration of the music-related data in the Sonic ROMs. I have no idea what kind of interest there may be in this, but let's give it a shot.

The ZIP file itself can be downloaded from the wiki (File:Sonic-Music-Hacking-Archive.zip - Sonic Retro). If anyone has any ideas where it might fit into the wiki, I'm all ears. I thought about the Sonic 2 Hacking Guide page, but I'm not totally sure if I like it there or not. Also, if anyone thinks I'm missing anything from the history, I'm all ears. I don't know much beyond 2004, because I started becoming a lot more detached from ROM hacking and didn't follow the goings-on in the community as much by that point.

The below text is from the README.txt file:

THE HISTORY:

Music hacking in Sonic ROMs came late in the pre-disassembly era. For several
years, it was largely ignored, and most people didn't seem to know what to do
with the information that was known about it. By 2004, music hacking was just
beginning to become mainstream, but the journey actually started back in 1999.

Playing music has been a hobby of mine since 1996 when I joined my middle
school's concert band, so when I got involved with Sonic ROM hacking in the
latter half of 1998, I knew that one of the things I wanted to figure out was
how to change the music in Sonic 2. However, I was not at all proficient in FM
synthesis and sequencing. That probably delayed me by several years from being
able to comfortably dive into the game's music. There were also not as many
ROM hacking "experts" back then, so I became one of those "experts" almost by
default, having been one of the most dedicated to the cause of documenting
each and every byte found in the ROM. But I wasn't of much use if I didn't
understand the basics behind digital music.

The first Sonic ROM hack to touch the music was the Sonic 1 Beta Hoax, done by
Cyan Helkaraxe and released on May 11, 1999. In it, certain FM channels are
muted. It was new and interesting at the time, because nobody had seen a ROM
hack with quite so many changes collectively, let alone a hack that makes the
music sound different.

In early 2000, I already knew generally where the music data was. However, I
knew very little about it. It wasn't until January 2001 that I began doing
experiments with the music. By November 2001, I knew what bytes controlled
what set of voices was to be used by each song, but didn't yet know how they
worked.

With enough knowledge of how the music sequence data was formatted, I was able
to make use of it. So on May 19, 2002, I released Sonic Timezones, a Sonic 2
final ROM hack that showcased a series of more technically advanced
modifications. One of the modifications included changes to three songs.
Tracks #01 and #12 were replaced with renditions of The Heart of Rock & Roll
(Huey Lewis and the News) and Yakety Sax (Boots Randolph) respectively. Track
#02 was a partial port of Green Hill Zone. This was the first time new music
had been introduced into a Sonic game.

On November 5, 2002, I publicly expressed interest in editing voice data after
having learned some about it on my dad's Yamaha DX7II-FD. However, I didn't
know where the voice data actually was, so I had to go digging around for it.

Eventually I found what I believed to be voice data and was clued in by some
specific byte value changes that reminded me of how certain parameter changes
on the DX7 would radically alter the tone. I eventually realized I had been
modifying two things: the envelope generator, and the algorithm. Moreover, I
started to realize that the value ranges were more in line with those on my
dad's Yamaha TX81Z. By mid-November, I was using the TX81Z to try and match up
all the various parameters I was changing. Given I had no technical knowledge
of the Yamaha OPN2 chip, I was crossing my fingers that I was onto something
with suspicions of a relationship between it and the TX81Z.

Aware of my endeavors, Cyan Helkaraxe sent me a program he created called the
YM2612 FM Patch Designer. It was a Genesis ROM that allowed common FM voice
parameters to be modified and tested in real-time, similar to how an actual
synthesizer would allow notes to be played while modifying instruments. I
thought it was one of the coolest things I had ever seen, and it further
peaked my curiosity about the the chip.

On November 24, I added all the new information I had gathered on music voice
and sequence data editing to the Sonic 2 Hacking Guide. That same day, I
created a hack of the Sonic 2 beta ROM that replaced song #81 with a full port
of Destructive Power from Chaotix. It was the first time an entire song had
been ported from one game to another. Enough was understood about the music by
that point that pretty much anything was possible.

While the Destructive Power hack was kept private, I was in the mood to put
something else out to the public that would get attention. The more attention
my work got, the more interest it tended to spark. I also wasn't sure how many
people actually tried Sonic Timezones and heard the music modifications I did
for that. So on December 1, I put out a hack that would replace song #81 with
a short rendition of Jingle Bells.

By December 9, I had approached Magus about writing a program to import voices
into the Sonic 2 beta ROM. He had previously written the ChaoSaX RXL Patcher
program at my request, so he was an obvious choice to do the same with a voice
program. However, I found myself looking into how to write the program I was
looking to have created. I ended up finding extensions for Multimedia Fusion
that would handle binary read/write operations on files. Having already been
well-aquainted with Clickteam products, I was eager to try my hand at it.

On March 30, 2003, I had put together beta version of a program I called Voice
Filer. It was designed to read external voice banks from various sources,
including my own custom YMB file format (later called YMX). The voices could
then be inserte as replacements for existing voices in the Sonic 2 beta ROM.

I publicly announced I was working on Voice Filer on April 5, but just two
days later, I was looking to also develop a music sequencer program capable of
importing MIDI files. I didn't know if I could pull it off as I knew nothing
about how MIDI files were formatted and if their data could easily be
translated into the format Sonic games required. Still I wanted to give it a
shot.

Before starting the sequencer program, I decided I really needed a channel
editor, and so I put one together and named the program Sonic QX. Version 0.02
Beta was released privately to testers to try out on April 19. By April 26,
the Voice Filer program had merged with Sonic QX, and I made another private
beta test release.

November 2003 saw the final pieces of Sonic QX starting to take form, first
with the capability to export drum samples from the Sonic 2 beta ROM to WAV
files, and then the MIDI importer I had wanted to do earlier in the year. On
November 30, the first MIDI import was achieved, though it remained unreleased
as I was not yet ready to make Sonic QX public yet.

Finally, on December 23, I released Sonic QX v0.31 Beta (build 13) for public
consumption. Minor refinements were made in the form of build 14, released on
December 26.

At long last, it seemed music hacking was finally getting the attention it
deserved. Sonic Timezones and the Jingle Bells hack didn't get a significant
rise out of people from the music standpoint, but the Sonic ROM hacking scene
seemed to latch onto Sonic QX in a big way now that they could import their
own songs with ease.

These days, many music modifications are done via trackers, something that I
only ever hoped to achieve with Sonic QX. Every new Sonic ROM hack is almost
guaranteed to have new music. Sonic QX didn't actually make any of this
possible, but through the allowance of MIDI importing, it seemed to lite the
fuse that got the ball rolling. Seeing (or in this case, hearing) really is
believing, and I think that inspired others to take music hacking seriously
and start developing their own software that would blow the doors wide off the
formerly no-go area of Sonic ROM hacking.
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Origins of Sonic Music Hacking

saxman

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