Music Hacking
From Sonic Retro
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Contents
Sonic 1
Music Locations
- Music Pointers: $71A9C
- Sound Effect Pointers: $78B44
DAC Samples
- DAC sample setup index: $D6
Each DAC pointer is listed one after another, and a single entry for one DAC sample is $8 bytes. The format is as follows:
Offset | Size | Description |
---|---|---|
$00-$01 | Word | Location of the DAC sample in decompressed driver.
|
$02-$03 | Word | Size of the compressed DAC sample in decompressed driver.
|
$05 | Byte | Sample rate/pitch. The lower the value, the faster the sample will play. |
$06-$08 | 3 Bytes | Unused/redundant. |
Sonic 1 has 3 DAC sample slots - one for the kick, one for the snare, and one for the Timpani. The other pitches of Timpani ($88-$8B) are defined by a special table, located at $71CC4, and are fully editable to suit other samples using the Timpani slot ($83).
The DAC sample definitions within songs:
Value | Sample |
---|---|
$81 | Kick |
$82 | Snare |
$83 | Hi-Timpani |
$84 | Noise |
$85 | Noise |
$86 | Noise |
$87 | Sega Sound |
$88 | Hi-Timpani |
$89 | Mid-Timpani |
$8A | Low-Timpani |
$8B | Low-Timpani |
Sonic 2 Beta
Music Locations
- Music Pointers (These add to $F0000, for 98-9F): $F0000
- Music Pointers (These add to $F8000): $F8000
- Pointer to Music Pointers at $F8000: $EC79D
- Sound Effect Pointers (These add to $F8000): $FF000
- Pointer to Sound Effect Pointers: $EC08E
DAC Samples
- Pointers to DAC Samples in Sonic 2 Beta: $ECDA6
Specifics...
- $ECDA6 - Sample 81 pointer
- $ECDA8 - Sample 81 length
- $ECDAA - Sample 82 pointer
- $ECDAC - Sample 82 length (skip FF)
- $ECDAF - Sample 83 pointer
- $ECDB1 - Sample 83 length
- $ECDB3 - Sample 84 pointer
- $ECDB5 - Sample 84 length (skip FF)
- $ECDB8 - Sample 85 pointer
- $ECDBA - Sample 85 length
- $ECDBC - Sample 86 pointer
- $ECDBE - Sample 86 length -- This one is tricky. You need to skip the second FF, as the first FF is valid.
These pointers are 4 bytes in size. First two bytes are the pointer to the sample (the pointers add to E0000, little endian, and don't follow the music pointer format. Simple 16-bit absolute), and the other two bytes are the length of the sample (also little endian). If you see an FF, skip it and move on to the next byte.
- DAC Master List in Sonic 2 Beta: $ECDC1
These work similarly to the master playlist in concept.. The format is two bytes per sample. First byte defines the sample ID, and the second byte defines the rate that the sample is played at. The lower the rate value, the faster the sample is played. This is used to make certain samples (like toms) appear to have different pitches (high tom, low tom, etc). If you see an FF, skip it and move on to the next byte. If you touch the FF, you fuck the entire sound driver. Don't. :P
The DAC sample definitions within songs:
Value | Sample |
---|---|
$81 | Kick |
$82 | Snare |
$83 | Clap |
$84 | Scratch |
$85 | Hi-Timpani |
$86 | Hi-Tom |
$87 | Silent |
$88 | Hi-Timpani |
$89 | Mid-Timpani |
$8A | Low-Timpani |
$8B | Low-Timpani |
$8C | Mid-Tom |
$8D | Low-Tom |
$8E | Floor-Tom |
$8F | Clap |
Sonic 2 Final
Music Locations
Sonic 2 Final
- Music Pointers (These add to F8000): F8000
- Specifics...
Pointer ID | Address | Sound Test ID | Song name |
---|---|---|---|
81 | $F84F6 | 08 | Casino Night Zone (2 Player) |
82 | $F88C4 | 02 | Emerald Hill Zone |
83 | $F8DEE | 05 | Metropolis Zone |
84 | $F917B | 09 | Casino Night Zone |
85 | $F9664 | 0B | Mystic Cave Zone |
86 | $F9A3C | 03 | Mystic Cave Zone (2 Player) |
87 | $F9D69 | 07 | Aquatic Ruin Zone |
88 | $FA36B | 0A | Death Egg Zone |
89 | $FA6ED | 12 | Special Stage |
8A | $FAAC4 | 11 | Option Screens |
8B | $FAC3C | 15 | Ending |
8C | $FB124 | 14 | Final Battle |
8D | $FB3F7 | 0E | Chemical Plant Zone |
8E | $FB81E | 13 | Boss |
8F | $FBA6F | 0D | Sky Chase Zone |
90 | $FBD8C | 04 | Oil Ocean Zone |
91 | $FC146 | 0F | Wing Fortress Zone |
92 | $FC480 | 0C | Emerald Hill Zone (2 Player) |
93 | $FC824 | 01 | 2 Player Results Screen |
94 | $FCBBC | 16 | Super Sonic |
95 | $FCE74 | 06 | Hill Top Zone |
96 | $FD48D | 18 | 1-Up |
97 | $FD193 | 19 | Title Screen |
98 | $FD35E | 1A | Stage Cleared |
99 | $FD57A | 1B | Game Over |
9A | $F8359 | 17 | Invincibility |
9B | $FD6C9 | 1D | Got an Emerald |
9C | $F803C | 10 | Hidden Palace Zone |
9D | $F823B | 1F | Underwater Timing |
9E | $FD797 | 1E | Credits |
- Pointer to Music Pointers at $F8000: $EC810
- Music Pointers (These add to F8000 and are for 98-9F, excluding continue): $F802A
- Specifics...
Pointer ID | Address | Sound Test ID | Song name |
---|---|---|---|
01 | 0F0002 | 1C | Continue |
- Sound Effect Pointers (These add to F8000): $FEE91
- Pointer to Sound Effect Pointers: $EC09C
DAC Samples
- Pointers to DAC Samples in Sonic 2 Final: $ECF7C
Specifics...
- $ECF7C - Sample 81 pointer
- $ECF7E - Sample 81 length
- $ECF81 - Sample 82 pointer
- $ECF83 - Sample 82 length
- $ECF85 - Sample 83 pointer
- $ECF87 - Sample 83 length
- $ECF8A - Sample 84 pointer
- $ECF8C - Sample 84 length
- $ECF8E - Sample 85 pointer
- $ECF90 - Sample 85 length
- $ECF93 - Sample 86 pointer
- $ECF95 - Sample 86 length
- $ECF97 - Sample 87 pointer
- $ECF99 - Sample 87 length
These pointers are 4 bytes in size. First two bytes are the pointer to the sample (the pointers add to E0000, little endian, and don't follow the music pointer format. Simple 16-bit absolute), and the other two bytes are the length of the sample (also little endian). If you see an FF, skip it and move on to the next byte.
- DAC Master List in Sonic 2 Final: $ECF9C
These work similarly to the master playlist in concept.. The format is two bytes per sample. First byte defines the sample ID, and the second byte defines the rate that the sample is played at. The lower the rate value, the faster the sample is played. This is used to make certain samples (like toms) appear to have different pitches (high tom, low tom, etc). If you see an FF, skip it and move on to the next byte. If you touch the FF, you fuck the entire sound driver. Don't. :P
The DAC sample definitions within songs:
Value | Sample |
---|---|
$81 | Kick |
$82 | Snare |
$83 | Clap |
$84 | Scratch |
$85 | Timpani |
$86 | Tom |
$87 | Bongo |
$88 | Hi-Timpani |
$89 | Mid-Timpani |
$8A | Low-Timpani |
$8B | Low-Timpani |
$8C | Mid-Tom |
$8D | Low-Tom |
$8E | Floor-Tom |
$8F | Hi-Bongo |
$90 | Mid-Bongo |
$91 | Low-Bongo |
Master Playlist
Sonic 2 has a special "master playlist" that defines what music ID plays in what slot. It works by taking a base address - generally the start of a music bank - and, for each increment of the value, it reads ahead another word in the current ROM bank. So, say, $00 would be the first word in the bank ($00-$01), $01 would be the next ($02-$03), and so on. The base address for this bank, in both Sonic 2 Beta AND final, is $F0000, and the addressing range spans as far as the value can allow, which is two Z80 ROM banks ($10000 bytes).
However, as a simple guide to understanding how it works (at least, for the casual hacker), all values for the original, untouched music (for the most part, anyway) subtract $1 from the value. So, to change Track 81 to Track 82, change $80 to $81. $80 is $81, $81 is $82, etc. These values go up to slot $9F, or $1F (visually, anyway - the game still uses $80 > values internally) in the final version of the game. The only exception to this is in Sonic 2 Beta, where some songs use the upper $8000 bytes of the bank start address to store music (making the values for calling said music start with $00). The locations for the master playlist are as follows:
- Master Playlist in Sonic 2 Beta: $ECE9F
- Master Playlist in Sonic 2 Final: $ECF36
As previously mentioned, track 81 is represented by $80, 82 is reresented by $81, etc. If you see an $FF, skip it and move on to the next byte - these are compression bytes for the driver, and touching them will bork the decompressor in-game, and prevent the sound driver from booting. The "master playlist" is only in Sonic 2 (Beta/Final) as far as I know. If I find it in any other games, I will update this section.
Music Compression
In Sonic 2 Final, there is a compression applied to all music data in the game except for the credits. This format has been dubbed the saxman compression, named after the person who cracked the format. I will not note how to manually decompress this format -- Refer to saxman's hacking guide to do so. The music can be decompressed by using Magus' Sega Data Compressor. Refer to the pointer format to edit the music properly.
Real-Time Music Editing
Offset | Z80 RAM Location | Purpose |
---|---|---|
$001669 | 11F5 | Master Playlist |
$000C16 | 07A2 | Pointer for Master Playlist |
$000DF9 | 0985 | Pointer for Sound Effects list |
Sonic 3 and Knuckles
- This section is at SCHG:Sonic_3_&_Knuckles/Music Editing.
Sonic 3D
Music Locations
- Music Pointers (These add to $C0000): $D3233
- Music Pointers (These add to $C8000): $D3245
- Music Pointers (These add to $D0000): $D325D
- Specifics...
Music ID | Music Pointer | Song name |
---|---|---|
These add to $C0000: | ||
01 | 2480 | Green Grove 1 |
02 | 8F91 | Green Grove 2 |
03 | A0A8 | Rusty Ruin 1 |
04 | E7B9 | Rusty Ruin 2 |
05 | 95C7 | Volcano Valley 2 |
06 | 4AD0 | Volcano Valley 1 |
07 | 39D7 | Spring Stadium 1 |
08 | 72E3 | Spring Stadium 2 |
09 | 91F0 | Diamond Dust 1 |
These add to $C8000: | ||
0A | 2480 | Diamond Dust 2 |
0B | DE8B | Gene Gadget 1 |
0C | BD96 | Gene Gadget 2 |
0D | A8A0 | Panic Puppet 2 |
0E | E0A8 | The Final Fight |
0F | B396 | Ending |
10 | 55BB | Bonus Stage |
11 | 8FC6 | Panic Puppet 1/Level Select Screen |
12 | 12D0 | Boss Theme 1 |
13 | 20D6 | Boss Theme 2 |
14 | 98DD | Intro |
15 | D9E1 | Credits |
These add to $D0000: | ||
16 | 2480 | Game Over |
17 | 7F82 | Congratulations: You have found the secret Level Select screen" screen |
18 | 9886 | Bonus Stage End |
19 | 158B | Extra Life |
1A | 658C | Chaos Emerald Gain |
1B | 558D | Invincibility |
1C | 2791 | Main Menu |
- Sound Effect Pointers (These add to $D8000): $D3297
DAC Samples
Location and format of the DAC sample table is unknown.
The DAC sample mapping is identical to that of Sonic 3 with many of the later samples removed.
Real-Time Music Editing
Offset | Z80 RAM Location | Purpose |
---|---|---|
$001AD0 | 165C | Music Pointers |
$001778 | 1304 | Pointer for Music Pointers |
$00177A | 1306 | Pointer for Sound Effect Pointers |
$001AD0 | 165C | Music Pointers |
$001B34 | 16C0 | Sound Effect Pointers |
Knuckles' Chaotix
Locations
- Music Pointers (These add to $40000): $76AE9
- Music Pointers (These add to $48000): $76B05
- Music Pointers (These add to $50000): $76B33
Address | Song |
---|---|
$40000 | Door Into Summer |
$40D61 | Electoria |
$41904 | Speed of Sound |
$428a6 | Seascape |
$4349a | Midnight Greenhouse |
$44220 | New Moon |
$4509c | Labyrinth |
$4536b | Trial and Error |
$45DEE | Walkin' |
$461be | Hyper-Hyper |
$468e5 | Evening Star |
$46Fe8 | Moonrise |
$474e3 | Overture |
$477f0 | This Horizon |
$48000 | Take Off |
$4836a | Combination |
$48a39 | Take a Nap |
$48c96 | Surging Power |
$4915d | Mechanical Dance |
$4951d | Tube Panic |
$49fb0 | Crystal Nightmare |
$4a58c | Child's Song |
$4ac3c | Soda Pop |
$4b082 | Pendulum |
$4b6f5 | Silver Screen |
$4bBFF | Tachy Touch |
$4c44e | Chaotic World |
$4c8fa | Surprise! |
$4cd0d | Nice Meeting You |
$4d0ef | Have a Happy Day |
$4d34c | Reach the Goal |
$4d53f | High Five |
$4d67a | Decision |
$4d81d | From Party to Party |
$4d9f4 | Have Some Fun |
$4dc41 | Oriental Legend |
$4e33d | Steel Heart |
$50000 | Tribute |
$509ac | Destructive Power |
$50c6a | Just Another Day |
$5400b | Decision 2nd |
- Sound Effect Pointers (These add to $50000): $76B3B
- PWM Table: $58000
PWM Samples
The note equivalents:
Value | Sample |
---|---|
$81 | Electric Kick |
$82 | Electric Snare |
$83 | Splash Cymbal |
$84 | Ride Bell |
$85 | High Tom |
$86 | Mid Tom |
$87 | Low Tom |
$88 | Electric Hi-Hat |
$89 | Crash Cymbal |
$8A | Clap |
$8B | Acoustic Kick |
$8C | Acoustic Snare |
$8D | Bell |
$8E | Fingers Snapping |
$8F | Cowbell |
$90 | High Click |
$91 | Low Click |
$92 | High Bongo |
$93 | Low Bongo |
$94 | High Timpani |
$95 | Low Timpani |
$96 | Silence |
Sonic Crackers
Music Locations
- Music Pointers: $0633F
- Specifics...
Sound ID | Song | Location |
---|---|---|
$81 | Electoria | $10000 |
$82 | Walkin' | $1088C |
$83 | Hyper-Hyper | $10BDA |
$84 | Evening Star | $11210 |
$85 | Moonrise | $1172B |
$86 | Game Over | $11B10 |
DAC Samples
Value | Sample |
---|---|
$81 | Kick |
$82 | Snare |
$83 | Tom |
$84 | Tom |
$85 | Tom |
$86 | Voice sample "Let's go!" |
$87 | Voice sample "Hey!" |
$88 | Beep/screech |
Tricks of the Trade
Music porting
Ah, yes. Music porting. An infamous practice that many want to achieve. This section will explain the various methods of porting music from one game to another. If something is not possible, it will be noted.
Sonic 1 -> Sonic 2 Beta
This is one of the easier jobs in my opinion, but it can be a bit tough at first. The trick is to convert the pointer format from S1 to S2B format. First, you have to convert the header pointers. This is the easiest part, as all the pointers are simple relative pointers. So here's what you do...
First off, mark the location you want to place the music at in pointer form. EX: F8000 goes to 8000, which goes to 0080, etc etc. Then, take this base location and add the relative values to it. So if I was placing my music at F9CDE, and my voice pointer was 0312, I would add 312 bytes to F9CDE. This gives me F9FF0. I then take this and convert it into pointer form. An easy way to do so in this case is to simply remove the F. This leaves me with 9FF0, which I then byteswap. This leaves me with the final converted pointer of F09F. Do this for every pointer in the header, as the rest you can leave intact.
The next job is to convert all the pointers in the coordination flags that have them. There are 3 flags in total that do so: F6, F7, and F8. Become familiar with the syntax; Know which is the pointer and which is not. Converting proceeds as follows...
We'll start with an example of sorts. As I noted before, with coordination flag pointers in S1, signed values are used. FFFF is 0, etc. The math works in the same way as our last job, but this time we use different variables. Our base location is found out by marking the offset of the byte where the actual pointer is. In the case of F6 and F8, the byte after F6/F8. In the case of F7, skip two bytes after the F7 to where the pointer is. This is all in my syntax breakdowns, BTW.
Now that we have our base location, we can convert the pointer. Now remember, instead of 0000 being zero, in this case FFFF is zero. So if we want to convert our pointer easily, we have to make our pointer as simple as the header pointers. For negative jumps (below FFFF), we take the pointer value and subtract it from FFFF. This will leave us with a simple relative value. For example, if my S1 pointer was FFE6, I would subtract FFE6 from FFFF. This gives me 19 as a result, meaning this pointer is meant to locate data 19 bytes before our base location. Now we have to convert this into S2B form. Take your base location and subtract your result relative value (19 in my case) from it. For example, if my base location was FEE90 (90EE), I would subtract 19 bytes from it (my result value from the above operation). That would give me the offset of FEE77. I then convert this into pointer form, giving me the final converted pointer of 77EE.
For positive values (above FFFF), things are a bit simpler. Simply take the positive value and subtract 1 from it. Then, add it to your base location. So if my pointer was 0090, I subtract 1 from it. This gives me 8F. I then add this value to my base location, which was FEE90. FEE90 + 8F = FEF1F. Then, convert this into S2B pointer form. This gives me the final converted pointer of 1FEF. Fun, eh? =P
Remember to do this with ALL pointers in the song. You won't get off correcting two or three, I'll tell you that much. :P
Points to note
Always remember to change the music pointer to point to your new music. Otherwise you'll have done this all for nothing. Also, S1 voices are not entirely compatible with S2 voices. You may have to apply new voices to the song to make it sound right. This is why the instruments in Esrael's port of Marble zone sounded different; he had to make new ones.
Porting between Sonic 3K/3D/Crackers/Chaotix
This job is much simpler, as all pointers use the same format. There are two methods of porting this music between each other...
- Simply put the music in the "same" location according to pointer format. For example, having music at C0000 or C8000 would be the same as having it at 10000 or 18000. All the result pointers would be 0080. Get it? =P Simple copy and paste, and nothing else needs to be done. Just change the music pointer to point to the new music and presto! Ported music. This method limits your customization as where to put the music though, and I don't recommend it unless you are porting whole music banks or it is incredibly convenient. It is easier though, so hey. =P
- Modify all pointers inside the music (header and coordination flags) to go along with the new location you put it at. Here's a simple way to do so...
First off, take your original location, which is the beginning of the song. Then, work out where you are going to put the song. Convert both these values into pointer format. Now, work out the difference between these two values. For example, if the original location was F802A (2A80 in pointer format), and I wanted to put it at FD980 (80D9 in pointer format), then I would subtract my new location from my original location. So in my case, FD980 - F802A. This gives me 5956. Now, this will be your modifying value for each pointer. You add this location to each pointer in the song to get your converted pointer.
Let me give an example of a negative value. My original location was FA000 and my new location was F9027. This time, we switch the operation. FA000 - F9027 = FD9. This time, you subtract this value from each pointer in the song to get the converted pointer. So remember, if you are moving a song to a location before the original location, subtract. If you are moving it to a location beyond the original, add.
Points to note
If Sonic 3 music has D817 as the voice pointer, then it cannot be ported outside of S3K without being given a new voice set. Sonic 3K is the only game with this universal voice bank, and specifying it in any other game will have no effect.
Porting from Sonic 2 Beta to Sonic 3K/3D/Crackers/Chaotix
This is a very simple job, provided you have a good eye for detail. The trick is to replace the differing coordination flags between the two games. This is a simple task, and you can do it in two simple steps.
- Run a search in the song for coordination flag E3. This is the S2 flag to return. We need to replace this with the Sonic 3K/etc equivalent, F9. Change all valid instances of E3 to F9. This will fix awkward jumps in the song that were hindering porting before.
- Run another search in the song for coordination flag E9. This is the S2 flag to add a value to the current channel pitch. We need to replace this with the Sonic 3K equivalent, FB. Change all valid instances of E9 to FB. This will fix certain lagging in some songs, lack of pitch change, and even crashing.
When I mention valid instances, I mean that the values of E9 or E3 are not part of another coordination flag. Make sure you know the format of most coordination flags, as to avoid making fatal mistakes that may destroy your entire port.
Points to note
Some voices may be wrong. You will have to fix this manually, provided you know how.
Porting from Sonic 3K/3D/Crackers/Chaotix to Sonic 2 Beta
Just do the opposite of the method above; replace F9 with E3 and FB with E9.