This article explains the structure of the sound data used in several SNES games developed by Winkysoft, for example Super Robot Wars 4.

Transfer Block Format

Each transfer block consists of multiple chunks laid out contiguously, having the following format: (all integers are little-endian, unless otherwise noted)

$0000:      xxxx        # size of chunk 1
$0002:      yyyy        # SPC start address of chunk 1
$0004:      .. .. ..    # chunk 1's xxxx bytes follow
$0004+xxxx: xxxx        # size of chunk 2
$0006+xxxx: yyyy        # SPC start address of chunk 2
$0008+xxxx: .. .. ..    # chunk 2's xxxx bytes follow
                        # ...
         ?: 0000        # transfer ends when xxxx == $0000
       ?+2: zzzz        # BGMs only; zzzz must be the song ID

As a special case, a transfer block that begins with 00 00 contains no chunks.

The SPC main program and all BGMs use this transfer format. BRR samples use a different format and have no separate chunks:

$0000: xxxx             # loop point relative to start of sample, in bytes
$0002: yyyy             # length of the sample, in bytes
$0004: .. .. ..         # yyyy bytes follow

Instrument Definition

Each instrument consists of 8 bytes:

$00: uu         # sample slot number
$01: vvvv       # controls the ADSR envelope, but doesn't seem to map directly to DSP register values?
$03: wwww       # *big-endian* sample pitch
$05: xx         # instrument volume, $FF = highest
$06: yy         # pan, $40 = center, $00 = right, $7F = left
$07: zz         # transpose, $00 = none, $0C = +1 octave, $E8 = -2 octaves

Instrument definitions are laid out contiguously.

Sequence Data Format

There is no header for sequence data; track 1's data immediately starts from the beginning of the sequence data area. Tracks 2 - 8 must be initialized using command $6E. A typical "header" looks like:

$5200: 69 0F 0C         # set up the FIR filter coefficients
$5203: 69 1F 21
$5206: 69 2F 2B
$5209: 69 3F 2B
$520C: 69 4F 13
$520F: 69 5F FE
$5212: 69 6F F3
$5215: 69 7F F9

$5218: 69 0C 00         # silence everything
$521B: 69 1C 00

$521E: 69 6D D9         # set up echo
$5221: 69 7D 03
$5224: 7F 22            # wait for a while to clear the echo buffer
$5226: 69 6C 00
$5229: 7F 22
$522B: 69 0C 7F         # reset SPC main volume
$522E: 69 1C 7F
$5231: 6D FF 5F 2C 2C   # toggle echo on selected channels, set feedback and echo levels

$5236: 6E 01 9C 53      # start tracks 2 - 8
$523A: 6E 02 C1 54      # e.g. track 3's sequence data begins at $54C1
$523E: 6E 07 18 56
$5242: 6E 04 DA 57
$5246: 6E 06 7C 59
$524A: 6E 05 38 5A
$524E: 6E 03 2E 5B

$5251: 74               # sequence data for track 1 follows

Sequence Commands

Command Description Arguments
$00-$66 Note none | (7D xx) | (7E yy) | (7F tt) | ([80-FE] yy tt)
$67 Pan Envelope pppp
$68 ??? xx
$69 DSP Write xx yy
$6A Vibrato Rate xx
$6B Noise Config xx
$6C Pitch Bend Depth xx
$6D Echo Config xx yy ll rr
$6E New Track xx pppp
$6F Percussion Mode none
$70 Detune ([80-FF] tt [80-FF]*)? [00-7F] tt
$71 Vibrato Depth ([80-FF] tt [80-FF]*)? [00-7F] tt
$72 Track Volume ([80-FF] tt [80-FF]*)? [00-7F] tt
$73 Pan xx
$74 Loop Start none
$75 Loop End xx
$76 Call Pattern pppp
$77 End of Pattern none
$78 End of Track none
$79 Tempo xx yy
$7A Transpose xx
$7B Instrument xx
$7C Rest tt
$7D Note velocity suffix xx
$7E Note length suffix yy
$7F Note wait time suffix tt

New Track

Spawns a track at the given pointer and starts playing it immediately. The track number ranges from $00 to $07; SFXs also use $08 and $09. (There is no need to use track number $00 because all tracks are spawned from track 1.)

$0000: 6E 03 CD AB      # point track 4 at $ABCD
$0004: 01

$ABCD: 02

# plays `01` and `02` simultaneously

End of Track

Stops the current track from reading new sequence data. All tracks should end with this command even if there is an infinite loop.

78      # end of track


Repeats all commands within the loop range for a given number of times. Up to 8 levels of nested loops are supported. A loop can also be made to repeat indefinitely by specifying a loop count of 0.

$0000: 74       # start loop 1
$0001: 74       #   start loop 2
$0002: 0A
$0003: 74       #     start loop 3
$0004: 0B
$0005: 75 02    #     end loop 3
$0007: 0C
$0008: 75 03    #   end loop 2
$000A: 0D
$000B: 75 00    # end loop 1

# the above repeats `0A 0B 0B 0C 0A 0B 0B 0C 0A 0B 0B 0C 0D` indefinitely

An indefinite loop resets the tempo multiplier.


Calls a pattern; the track pointer continues from the given address until the end-of-pattern marker is found, then control returns to the point just after the pattern call. There are no nested patterns; calling a pattern inside another pattern will crash the sound engine.

$0000: 76 CD AB # call pattern at $ABCD
$0003: 03

$ABCD: 01
$ABCE: 02
$ABCF: 77       # end of pattern

# the above is equivalent to `01 02 03`


Plays a note. The command byte gives the note pitch in the number of semitones (unless percussion mode is enabled), but there isn't a unique middle C because each instrument might be tuned differently; usually $3C is customarily chosen as middle C. The full form takes 3 arguments, and specifies the velocity (+ $80, default is $C0), note length (in ticks, $C0 = whole note), and wait time (also in ticks) all at once:

$0000: 3C C0 16 18      # C-5, velocity 64, 22 ticks, 8th note
$0004: 3F E4 5D 60      # Eb5, velocity 100, 93 ticks, half note

If the second byte is $7D, $7E, or $7F, then the next byte changes only the velocity (without the + $80), note length, or wait time of subsequent notes respectively:

$0008: 30 7D 50         # C-4, velocity 80, 93 ticks, half note
$000B: 35 7E 2E         # F-4, velocity 80, 46 ticks, half note
$000E: 3A 7F 30         # Bb4, velocity 80, 46 ticks, quarter note

Otherwise, the second byte must be either another new note or a sequence command. In this case all these settings are copied from previous notes:

$0012: 39               # A-4, velocity 80, 46 ticks, quarter note
$0013: 40               # E-5, velocity 80, 46 ticks, quarter note

Normally the note length must be shorter than the wait time, so that the current note is cut before a new one is played. To suppress this, a note length of $FF should be used, which indicates the note should never be cut, producing a tie or a legato depending on the next note. This is useful for e.g. having notes longer than $FF ticks or changing the volume in the middle of a note:

$0014: 3C C0 FF C0      # C-5, velocity 64, tie, whole note
$0018: 3C 7D B0         # C-5, velocity 48, tie, whole note
$001B: 3C 7E BE         # C-5, velocity 48, 190 ticks, whole note

# plays a single note for 3 full measures, with a lower velocity in the last 2

7F tt alone is occasionally used to represent rests, but this is only valid if no notes have been played.


Plays nothing for the given number of ticks.

7C 30   # quarter note rest

Percussion Mode

Toggles percussion mode on or off. The following apply while percussion mode is on:

  • The channel's pitch is always exactly the pitch value given in the active instrument, so all pitch effects are disabled.
  • Each new note's command byte selects the instrument for that ID, instead of representing a pitch value.
$0000: 6F               # turn on percussion mode
$0001: 01 C0 2E 30      # play instrument $01 at a fixed pitch
$0005: 6F               # turn off percussion mode
$0006: 01               # play the C#0 note


Selects the instrument with the given ID. Resets the pan and transpose commands.

7B 13   # select instrument $13


Sets the channel pan position. $7F is left, $00 is right, and $40 is the center. This modifies the pan setting of the active instrument directly.

73 20   # set pan to 50% right
73 50   # set pan to 25% left


Transposes all following notes on the current track by the given (signed) number of semitones. This modifies the transpose setting of the active instrument directly, so 00 will not always reset the transpose.

7A 04   # set instrument transpose to +4 semitones
7A E8   # set instrument transpose to -2 octaves

Pan Envelope

Applies a pan envelope starting at the given address that runs independently of new notes. The pan envelope has the following interpretation: $F0 is right, $FF is left, $F8 is the center, $01-$EF are wait times, and $00 stops the envelope. (These wait times seem to desync from notes quite easily.)

$0000: 67 CD AB         # play pan envelope at $ABCD

$ABCD: F0 14            # pan 100% right for 20 ticks
$ABCF: FC 28            # pan 50% left for 40 ticks
$ABD1: 00               # end pan envelope

Pitch Bend

Applies a linear bend to the frequencies of all subsequent notes by the given signed depth.

6C 05   # bend upwards slowly
6C F1   # bend downwards, 3x as fast as above
6C 00   # disable pitch bend


Applies a detune multiplier. All notes' frequency are multiplied by xx / $40, the maximum value for xx being $7F. The last argument is a wait time, measured in ticks.

70 60 00        # multiply all note frequencies by 150%
70 30 18        # multiply all note frequencies by 75%, then wait for an 8th note

If the multiplier is greater than $7F, that value minus $80 is the actual detune value used, and a detune envelope is produced. Multiple envelope values greater than $7F may follow, all having the same wait time, until the last non-envelope value is found (this multiplier value has its own required wait time argument).

70 FD 09        # multiplier 125, wait for 9 ticks
   F8           # multiplier 120, wait for 9 ticks
   EE           # multiplier 110, wait for 9 ticks
   E4           # multiplier 100, wait for 9 ticks
   5A 12        # multiplier 90, wait for 18 ticks, end of envelope


Causes the current track to oscillate in pitch. The vibrato depth and rate are controlled by commands $71 and $6A respectively, the former of which supports envelopes like the detune command.

71 08 00        # moderate vibrato
71 32 00        # strong vibrato
6A 01           # extremely slow vibrato
6A 50           # fast vibrato

Track Volume

Changes the current track's volume. Default is $40. Supports envelopes like the detune command.

72 50 00        # set track volume to 80


Applies a multiplier to the global tempo, with $80 being the default. The resulting BPM can overflow if it is too high. Some BPM values may cause tracks to desync.

79 C0 00        # set tempo to 150% (overflows if song BPM is greater than 170)

The second argument controls the rate of the BPM change. A value of 0 represents an instant change, 1 represents a slow change, and higher values produce a faster change.

79 60 02        # change tempo to 75% slowly

DSP Write

Writes the given value to the given SPC DSP register.

69 0F 7F        # write $7F to register $0F (COEF0, filter coefficient 0)
69 1C 64        # write $64 to register $1C (MVOL (R), right main volume)

Echo Config

Changes several echo parameters at once: enabled tracks (EON), feedback level (EFB), left echo volume (EVOL (L)), right echo volume (EVOL (R)), in that order given.

6D FF 5F 2C 2C  # enable echo on all tracks, set feedback to +95, set echo volume to 44

Noise Config

If the given argument is within $00-$1F, enables white noise on the current track with that given pitch ($1F being the highest), otherwise disables noise output.

6B 1D   # enable noise
6B FF   # disable noise

Game-Specific Notes

Super Robot Wars 4 (第4次スーパーロボット大戦)

The main SPC program is referred from $E20000 (file offset $220000). It has 3 chunks:

  • ROM:$E20304-$E20583 -> SPC:$0380-$05FF: Instrument definitions for ID $30-$7F, probably all for sound effects.
  • ROM:$E20588-$E21942 -> SPC:$07F8-$1BB2: 4 unknown pointers, followed by a 64-entry table of tempo and main volume values for each BGM. The rest of the chunk appears to be for sound effects.
  • ROM:$E21947-$E224A0 -> SPC:$F180-$FCD9: The sound driver code.

Some of the tempo and main volume values are as follows:

                                  # ...
ROM:$220596, SPC:$0806: AA 96     # BGM $03: 170 BPM, 150 main volume (Valsion)
ROM:$220598, SPC:$0808: 92 E9     # BGM $04: 146 BPM, 249 main volume (Gallant Char)
ROM:$22059A, SPC:$080A: B3 A0     # BGM $05: 179 BPM, 160 main volume (Mazinger Z)
                                  # ...

BGMs $00-$3F are referred from the far pointer table at $E28000-$E280BF. Some song IDs are unused; these BGMs have no chunks, but nonetheless contain 00 00 xx 00 as their data where xx is the song ID. The remaining used BGMs each use 2 chunks. The first chunk is mapped to $0200 and contains custom instruments; all IDs within $00-$2F are available. The second chunk is mapped to $5200 and contains the sequence data. Custom samples immediately follow the sequence data so there is usually no need to worry about running out of space.

The far pointer table at $E20003-$E202FF refers to samples $01-$FF. A separate near pointer table at $E30000-$E301FF, indexed by the song ID, controls which samples are loaded into which slots for every BGM and SFX. The actual load table has the following format:

$0000: aa xx    # load sample xx into slot number aa
$0002: bb yy    # load sample yy into slot number bb
                # ...
    ?: FD       # end of BGM load table (SFX load tables end with FF instead)

BGM $01 loads the sample data for slots $00-$10; these samples are shared across all BGMs and SFXs. Songs are free to use the slot range $18-$20 (and probably higher slot numbers too, provided the samples don't overlap with the echo buffer).

All SPC transfers are complete at $808404; SPC files can be readily dumped if a breakpoint is placed there.

Karaoke Mode

The bytes at $CDEF41-$CDEF4E contain the song IDs for the BGMs available in karaoke mode. Lyrics are accessed through the near pointer table at $CB667C-$CB678B, which in turn is referred from $C9010B.

The cue points for the lyrics are stored as if they were a BRR chunk with a loop point of 0 and an ID of the BGM's ID + $C0. For example, the cue points for Mazinger Z (song ID $05, cue ID $C5) look like:

$E22531: 00 00  # must be 0
$E22533: 80 00  # length of the following chunk (i.e. $E225B4 - $E22535 + 1)

# note that 8 measures total 192 * 8 = 1536 ticks, so the lyrics are slightly ahead of the actual song
$E22535: F0 F0 F0 F0 F0 F0 F1 56                                        # wait for 240 * 6 + 86 = 1526 ticks

$E2253D: 48 78 18 18 18 18 48 30 18 18 18 30 30 C0                      # 空にそびえる  くろがねの城
$E2254B: 18 30 18 60 18 18 18 18 60 18 18 18 0C 3C 30 C0                # スーパーロボット  マジンガーZ

$E2255B: 18 30 18 48 0C 0C 18 18 18 18 18 30 18 C0 F1 C0                # 無敵の力は  ぼくらのために
$E2256B: 30 18 18 48 18 18 18 18 18 18 48 02 02 BC C0                   # 正義の心を  パイルダーオン!

$E2257A: 18 30 18 60 0C 3C 0C 0C 48 18 F1 18 18 18 18 18 30 18 C0       # とばせ  てっけん  ロケットパンチ
$E2258D: 18 30 18 60 18 18 18 18 60 18 18 18 18 0C 0C 30 18 C0 C0       # いまだ  だすんだ  ブレストファイヤー

$E225A0: 18 0C 24 0C 60 0C 18 0C 24 0C 60 0C                            # マジンゴー  マジンゴー
$E225AC: F1 30 30 30 30 0C B4 C0                                        # マジンガーZ

$E225B4: FF                                                             # end of cue points

A value lower than $F0 advances the lyrics by one character and then waits for that number of ticks; all spaces and end-of-string markers also count as characters. $F0 and $F1 xx wait for exactly 240 or xx ticks respectively, without consuming a character, and $F2 to $FF all finish the cue points (only $FF is used).

Displaying the lyrics during the karaoke sequence is done with the near pointer table at $D25E80-$D25E9F, indexed by song list order. Again, using Mazinger Z as an example:

$D25EA0: C6 00 EB 01 00 01      # display lyrics $00-$01, offsetted by 5 and 10 tiles respectively
$D25EA6: C6 02 EB 03 02 03
$D25EAC: C6 04 EB 05 04 05
$D25EB2: C6 06 F0 07 06 07      # lower line ("マジンガーZ") is offsetted by 15 tiles here
$D25EB8: FF

The different commands are as follows:

  • $00-$BF: Steps through the lyrics of that given line.
  • $C0-$DF xx: Clears both lines, then displays lyrics xx on the upper line, offsetted by (command byte - $C1) tiles.
  • $E0-$FE xx: Clears the lower line, then displays lyrics xx on it, offsetted by (command byte - $E1) tiles.
  • $FF: Finishes the karaoke sequence.

All the karaoke sequences in the game have the form of [C0-DF] xx [E0-FE] yy xx yy or [C0-DF] xx xx.

Super Robot Wars 3 (第3次スーパーロボット大戦)

The main SPC program is referred from $288000 (file offset $140000). It has 5 chunks:

  • ROM:$1400EE-$140454 -> SPC:$F180-$F4E6: Presumably contains the tempo and main volume values for each track.
  • ROM:$140459-$140460 -> SPC:$23F8-$23FF: 4 unknown pointers.
  • ROM:$140465-$1405B4 -> SPC:$04B0-$05FF: Instrument definitions for ID $5A-$7F, probably all for sound effects.
  • ROM:$1405B9-$14103E -> SPC:$1770-$21F5: Probably sequence data for sound effects.
  • ROM:$141043-$14190E -> SPC:$F500-$FDCB: The sound driver code.

Instrument definitions are mapped to $0200 as above. Sequence data is mapped to $0600 instead, which means only $1170 bytes are available.

The BRR table is located at $288003-$2880E6, the BGM table at $298000-$298071, and the sample load table at $2A8000-$2A80FF. The sample load entries appear to use a slightly different format than SRW4.

This earlier revision of the sound driver does not support commands $67 and $68, so these become note commands.

Super Robot Wars EX (スーパーロボット大戦EX)

The main SPC program is referred from $298000 (file offset $148000). The data layout resembles SRW3.

Instrument definitions are mapped to $0200. Sequence data is mapped to $0600.

The BRR table is located at $298003-$2980EF, the BGM table at $2A8000-$2A8071, and the sample load table at $2B8000-$2B8109. The same caveats for SRW3 should also apply here.

Super Robot Wars Gaiden: Masoukishin – The Lord Of Elemental (スーパーロボット大戦外伝 魔装機神)

The main SPC program is referred from $E30000 (file offset $230000). The data layout resembles SRW4.

Instrument definitions are mapped to $0200. Sequence data is mapped to $3C00.

The BRR table is located at $E30003-$E302FF, the BGM table at $E38000-$E380BF, and the sample load table at $E40000-$E401FF.

Battle Robot Retsuden (バトルロボット烈伝)

The main SPC program is referred from $D80000 (file offset $180000). The data layout resembles SRW4.

Instrument definitions are mapped to $0200. Sequence data is mapped to $7400.

The BRR table is located at $D80003-$D802FF, the BGM table at $D88000-$D880BF, and the sample load table at $D90000-$D901FF.


This article is authored by HertzDevil. The most up-to-date revision can be found here.