Sonic & Knuckles Collection/Technical information/Music and sound effects

Back to: Sonic & Knuckles Collection/Technical information.

SCHG: Sonic the Hedgehog 3 & Knuckles
Main Article
Art Editing
Editing Art Uncompressed Art Nemesis Format Art Kosinski Format Art Palette Editing Palette Locations Pattern Load Requests
Object Editing
Editing Objects Object Pointers Object Pointer List #1 Object Pointer List #2 Objects not in either list Sprite Mappings Dynamic PLCs
Level Editing
Editing Levels Object Placement Ring Placement Level Layout 16x16 Block Mappings 128x128 Block Mappings
Music Editing
Editing Music Pointer Format Header Format DAC Samples Universal Voice Bank Music Pointers (Sonic & Knuckles) Music Pointers (Sonic 3)
RAM Editing
Editing RAM Main System Memory Locations Object Status Table Format
Sonic & Knuckles Collection
Sonic & Knuckles Collection Music and sound effects

Note: All data is little endian unless stated otherwise.

Music

Music playback is handled by the external DLL MIDIOUT.DLL. Music tracks are stored in the DLL as "CMP" resources. These can be converted to and from standard MIDI files using SKC-Midi.

API

GetMidiInterface returns a pointer to a MidiInterfaceClass class. This class provides the following methods:

Function	Description
BOOL init(HWND hwnd)	Initialise the playback code. If playback reaches the end of a non-looping track, an application-defined message with an identifier of 0x464 is posted to the HWND supplied to this function.
BOOL loadSong(short id, unsigned int bgmmode)	Loads the specified song into memory. Valid values for bgmmode are: 0 = FM Synthesizer 1 = General MIDI
BOOL playSong()	Starts playback of the currently loaded song.
BOOL stopSong()	Stops playback of the currently loaded song.
BOOL pauseSong()	Pauses playback of the currently loaded song.
BOOL resumeSong()	Resumes playback of the currently loaded song.
BOOL setTempo(unsigned int pct)	Changes the tempo of the currently loaded song. The default tempo is 100.

Compression

This short section needs expansion. You can help Sonic Retro by adding to it.

Format

Once decompressed, tracks are stored using the following format:

Offset	Type	Description
0	4 bytes	Time Division.
4	4 bytes	Number of events.
8	4 bytes	Unknown.
12	4 bytes	Unknown.
16	8 * (number of events) bytes	Array of MIDI events (8 bytes each) Offset Type Description 0 4 bytes Event delta time. 4 3 bytes Event data. The purpose depends on the event type. 7 1 byte Event type. Can be one of the following values: $00 MIDI Channel Event. The event data contains the numeric value and parameters. $01 Tempo Event. The event data contains the sequence tempo in terms of microseconds per quarter-note. $02 Loop Start/End. The event data is unused.

Sound effects

Sound effects are stored in the SONIC3K.DS2 file, in 8-bit unsigned Mono at 22kHz. This can be edited using SKCsnd.

The file format consists of a 32-bit integer containing the number of sound effects, followed by an array of 32-bit integers containing the length of each sound effect in bytes. After this is the sound data as raw PCM for each sound effect stored sequentially until the end of the file.