N-SPC Engine/Nintendo/Koji Kondo/SFX Sequence Format
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The SFX sequence data is slightly modified compared to the standard N-SPC's voice command format. These are headerless, unlike a song, and they only support one channel at a time, with the channel used being fixed. Both games have almost the same command set except for VCMD $FF.
All SFX are initially handled at a tempo of $38.
| VCMD ID | Description | Arguments |
|---|---|---|
| $00 | End of SFX | |
| $01-$7F | Note Duration | xx |
| $80-$C5 | Note | |
| $C6-$CF | Tie | |
| $D0-$D9 | Percussion | |
| $DA | Instrument | xx |
| $DB-$DC | Invalid Note | |
| $DD | Pitch Slide to Note | xx yy zz aa |
| $DE-$EA | Invalid Note | |
| $EB | Note Pitch Envelope To | xx yy zz |
| $EC-$FE | Invalid Note | |
| $FF | Restart SFX (Super Mario World CPUIO0) | |
| $FF | Jump Back One Byte (Super Mario World CPUIO3) | |
| $FF | Jump to SFX ID (Pilotwings) | xx |
SFX Instrument Format
The SFX instrument format, shared among all SFX but not consistently stored in terms of memory location, consists of a series of bytes corresponding to direct DSP register writes to the following in order (with the last one not being a DSP register write at all)...
- VxVOLL
- VxVOLR
- VxPITCHL
- VxPITCHH
- VxSRCN
- VxADSR1
- VxADSR2
- VxGAIN
- Pitch Base Multiplier
SFX Percussion Format
This is identical to the music percussion format.
SFX Voice Command Format
Invalid Note (VCMD $DB-$DC, $DE-$EA, $EC-$FE)
Doesn't crash the sound driver, but does play an invalid note.
End of SFX (VCMD $00)
Terminates the SFX.
Note Duration (VCMD $01-$7F)
%0xxxxxxx (yy)
- xxxxxxx represents your note length (as seven bits) in tempo ticks.
- yy, if less than $7F, represents the volume of the note.
Note (VCMD $80-$C5)
Plays a note and delays the channel for one note length before reading another VCMD.
Tie (VCMD $C6-$CF)
Continues playing the previous note and delays the channel for one note length before reading another VCMD.
Note that for SFX, there is no rest command.
Percussion (VCMD $D0-$D9)
Plays a percussion note. Unlike SFX, percussion uses the same set that the music uses, and thus has the same instrument format as that.
Instrument (VCMD $DA)
$DA xx
- xx is an instrument ID to an array of instruments. See SFX Instrument Format above for the format.
Pitch Slide To Note (VCMD $DD)
$DD xx yy zz aa
- xx is the starting note.
- yy defines the number of tempo ticks to delay the slide for.
- zz defines the length of the pitch slide in tempo ticks.
- aa is the target note.
Note Pitch Envelope To (VCMD $EB)
$EB xx yy zz
This VCMD is applied to all subsequent notes until turned off or overwritten.
- xx is the number of ticks to delay before applying the pitch envelope.
- yy is the length of the pitch slide in tempo ticks.
- zz is the target note.
Restart SFX (VCMD $FF)
Only compatible with Super Mario World when playing SFX through the CPUIO0 register.
Restarts the SFX from the beginning.
Jump Back One Byte (VCMD $FF)
Only compatible with Super Mario World when playing SFX through the CPUIO3 register.
Normally, the pointer is incremented upon reading the VCMD. This causes the inverse to happen, and sets the pointer to one byte before this VCMD.
Jump to SFX ID (VCMD $FF)
Only compatible with Pilotwings.
$FF xx
- xx is the SFX ID to jump to. The array used depends on which set of sequences you're using, as the two of them use different sets.