furnace/papers/format.md

the Furnace file format (.fur)

while Furnace works directly with the .dmf format, I had to create a new format to handle future additions to the program.

this document has the goal of detailing the format.

information

all numbers are little-endian.

the following fields may be found in "size":

• f indicates a floating point number.
• STR is a UTF-8 zero-terminated string.
• ??? is an array of variable size.
• S?? is an array of STRs.
• 1?? is an array of bytes.
• 2?? is an array of shorts.
• 4?? is an array of ints.

the format has changed several times across versions. a (>=VER) indicates this field is only present starting from format version VER, and (<VER) indicates this field is present only before version VER.

furthermore, an or reserved indicates this field is always present, but is reserved when the version condition is not met.

format versions

the format versions are:

• 59: Furnace dev59

• 58: Furnace dev58

• 57: Furnace dev57

• 53: Furnace 0.5.7

• 52: Furnace 0.5.7pre4

• 51: Furnace 0.5.7pre3

• 50: Furnace 0.5.7pre2

• 49: Furnace 0.5.7pre1

• 48: Furnace 0.5.6

• 47: Furnace 0.5.6pre1

• 46: Furnace 0.5.5

• 45: Furnace 0.5.5pre3

• 44: Furnace 0.5.5pre2

• 43: Furnace 0.5.5pre1

• 42: Furnace 0.5.4

• 41: Furnace 0.5.3

• 40: Furnace 0.5.2

• 39: Furnace 0.5.2pre3

• 38: Furnace 0.5.2pre2

• 37: Furnace 0.5.2pre1

• 36: Furnace 0.5.1

• 35: Furnace 0.5

• 27: Furnace 0.4.6

• 26: Furnace 0.4.6pre1

• 25: Furnace 0.4.5

• 24: Furnace 0.4.4

• 23: Furnace 0.4.3

• 22: Furnace 0.4.2

• 21: Furnace 0.4.1

• 20: Furnace 0.4

• 19: Furnace 0.4pre3

• 18: Furnace 0.4pre2

• 17: Furnace 0.4pre1

• 16: Furnace 0.3.1

• 15: Furnace 0.3

• 14: Furnace 0.2.2

• 13: Furnace 0.2.1

• 12: Furnace 0.2

header

the header is 32 bytes long.

size	description
16	"-Furnace module-" format magic
2	format version
2	reserved
4	song info pointer
8	reserved

song info

size	description
4	"INFO" block ID
4	reserved
1	time base
1	speed 1
1	speed 2
1	initial arpeggio time
4f	ticks per second
- 60 is NTSC
- 50 is PAL
2	pattern length
2	orders length
1	highlight A
1	highlight B
2	instrument count
2	wavetable count
2	sample count
4	pattern count
32	list of sound chips
- possible soundchips:
- 0x00: end of list
- 0x01: YMU759 - 17 channels
- 0x02: Genesis - 10 channels (compound!)
- 0x03: SMS (SN76489) - 4 channels
- 0x04: Game Boy - 4 channels
- 0x05: PC Engine - 6 channels
- 0x06: NES - 5 channels
- 0x07: C64 (8580) - 3 channels
- 0x08: Arcade (YM2151+SegaPCM) - 13 channels (compound!)
- 0x09: Neo Geo (YM2610) - 13 channels
- bit 6 enables alternate mode:
- 0x42: Genesis extended - 13 channels
- 0x43: SMS (SN76489) + OPLL (YM2413) - 13 channels (compound!)
- 0x46: NES + VRC7 - 11 channels (compound!)
- 0x47: C64 (6581) - 3 channels
- 0x49: Neo Geo extended - 16 channels
- bit 7 for non-DefleMask chips:
- 0x80: AY-3-8910 - 3 channels
- 0x81: Amiga - 4 channels
- 0x82: YM2151 alone - 8 channels
- 0x83: YM2612 alone - 6 channels
- 0x84: TIA - 2 channels
- 0x85: VIC-20 - 4 channels
- 0x86: PET - 1 channel
- 0x87: SNES - 8 channels
- 0x88: VRC6 - 3 channels
- 0x89: OPLL (YM2413) - 9 channels
- 0x8a: FDS - 1 channel
- 0x8b: MMC5 - 3 channels
- 0x8c: Namco 163 - 8 channels
- 0x8d: OPN (YM2203) - 6 channels
- 0x8e: PC-98 (YM2608) - 16 channels
- 0x8f: OPL (YM3526) - 9 channels
- 0x90: OPL2 (YM3812) - 9 channels
- 0x91: OPL3 (YMF262) - 18 channels
- 0x92: MultiPCM - 24 channels
- 0x93: Intel 8253 (beeper) - 1 channel
- 0x94: POKEY - 4 channels
- 0x95: RF5C68 - 8 channels
- 0x96: WonderSwan - 4 channels
- 0x97: Philips SAA1099 - 6 channels
- 0x98: OPZ (YM2414) - 8 channels
- 0x99: Pokémon Mini - 1 channel
- 0x9a: AY8930 - 3 channels
- 0x9b: SegaPCM - 16 channels
- 0x9c: Virtual Boy - 6 channels
- 0x9d: VRC7 - 6 channels
- 0x9e: YM2610B - 16 channels
- 0x9f: ZX Spectrum (beeper) - 6 channels
- 0xa0: YM2612 extended - 9 channels
- 0xa1: Konami SCC - 5 channels
- 0xa2: OPL drums (YM3526) - 11 channels
- 0xa3: OPL2 drums (YM3812) - 11 channels
- 0xa4: OPL3 drums (YMF262) - 20 channels
- 0xa5: OPL3 4-op (YMF262) - 12 channels
- 0xa6: OPL3 4-op + drums (YMF262) - 14 channels
- 0xa7: OPLL drums (YM2413) - 11 channels
- 0xa8: Atari Lynx - 4 channels
- 0xe0: QSound - 19 channels
- (compound!) means that the system is composed of two or more chips,
and has to be flattened.
32	sound chip volumes
- signed char, 64=1.0, 127=~2.0
32	sound chip panning
- signed char, -128=left, 127=right
128	sound chip parameters (TODO)
STR	song name
STR	song author
4f	A-4 tuning
1	limit slides (>=36) or reserved
1	linear pitch (>=36) or reserved
1	loop modality (>=36) or reserved
1	proper noise layout (>=42) or reserved
1	wave duty is volume (>=42) or reserved
1	reset macro on porta (>=45) or reserved
1	legacy volume slides (>=45) or reserved
1	compatible arpeggio (>=45) or reserved
1	note off resets slides (>=45) or reserved
1	target resets slides (>=45) or reserved
1	arpeggio inhibits portamento (>=47) or reserved
1	wack algorithm macro (>=47) or reserved
1	broken shortcut slides (>=49) or reserved
1	ignore duplicate slides (>=50) or reserved
6	reserved
4??	pointers to instruments
4??	pointers to wavetables
4??	pointers to samples
4??	pointers to patterns
???	orders
- a table of shorts
- size=channels*ordLen
- read orders than channels
???	effect columns
- size=channels
1??	channel hide status
- size=channels
1??	channel collapse status
- size=channels
S??	channel names
- a list of channelCount C strings
S??	channel short names
- same as above
STR	song comment
4f	master volume, 1.0f=100% (>=59)
this is 2.0f for modules before 59

instrument

size	description
4	"INST" block ID
4	reserved
2	format version (see header)
1	instrument type
- 0: standard
- 1: FM
- 2: Game Boy
- 3: C64
- 4: Amiga/sample
1	reserved
STR	instrument name
---	FM instrument data
1	alg
1	feedback
1	fms
1	ams
1	operator count (always 4)
3	reserved
---	FM operator data × 4
1	am
1	ar
1	dr
1	mult
1	rr
1	sl
1	tl
1	dt2
1	rs
1	dt
1	d2r
1	ssgEnv
1	dam
1	dvb
1	egt
1	ksl
1	sus
1	vib
1	ws
1	ksr
12	reserved
---	Game Boy instrument data
1	volume
1	direction
1	length
1	sound length
---	C64 instrument data
1	triangle
1	saw
1	pulse
1	noise
1	attack
1	decay
1	sustain
1	release
2	duty
1	ring mod
1	osc sync
1	to filter
1	init filter
1	vol macro is cutoff
1	resonance
1	low pass
1	band pass
1	high pass
1	channel 3 off
2	cutoff
1	duty macro is absolute
1	filter macro is absolute
---	Amiga instrument data
2	initial sample
14	reserved
---	standard instrument data
4	volume macro length
4	arp macro length
4	duty macro length
4	wave macro length
4	pitch macro length (>=17)
4	extra 1 macro length (>=17)
4	extra 2 macro length (>=17)
4	extra 3 macro length (>=17)
4	volume macro loop
4	arp macro loop
4	duty macro loop
4	wave macro loop
4	pitch macro loop (>=17)
4	extra 1 macro loop (>=17)
4	extra 2 macro loop (>=17)
4	extra 3 macro loop (>=17)
1	arp macro mode
1	reserved (>=17) or volume macro height (>=15) or reserved
1	reserved (>=17) or duty macro height (>=15) or reserved
1	reserved (>=17) or wave macro height (>=15) or reserved
4??	volume macro
4??	arp macro
- before version 31, this macro's values were stored offset by 12.
4??	duty macro
4??	wave macro
4??	pitch macro (>=17)
4??	extra 1 macro (>=17)
4??	extra 2 macro (>=17)
4??	extra 3 macro (>=17)
4	alg macro length (>=29)
4	fb macro length (>=29)
4	fms macro length (>=29)
4	ams macro length (>=29)
4	alg macro loop (>=29)
4	fb macro loop (>=29)
4	fms macro loop (>=29)
4	ams macro loop (>=29)
1	volume macro open (>=29)
1	arp macro open (>=29)
1	duty macro open (>=29)
1	wave macro open (>=29)
1	pitch macro open (>=29)
1	extra 1 macro open (>=29)
1	extra 2 macro open (>=29)
1	extra 3 macro open (>=29)
1	alg macro open (>=29)
1	fb macro open (>=29)
1	fms macro open (>=29)
1	ams macro open (>=29)
4??	alg macro (>=29)
4??	fb macro (>=29)
4??	fms macro (>=29)
4??	ams macro (>=29)
---	operator macro headers × 4 (>=29)
4	AM macro length
4	AR macro length
4	DR macro length
4	MULT macro length
4	RR macro length
4	SL macro length
4	TL macro length
4	DT2 macro length
4	RS macro length
4	DT macro length
4	D2R macro length
4	SSG-EG macro length
4	AM macro loop
4	AR macro loop
4	DR macro loop
4	MULT macro loop
4	RR macro loop
4	SL macro loop
4	TL macro loop
4	DT2 macro loop
4	RS macro loop
4	DT macro loop
4	D2R macro loop
4	SSG-EG macro loop
1	AM macro open
1	AR macro open
1	DR macro open
1	MULT macro open
1	RR macro open
1	SL macro open
1	TL macro open
1	DT2 macro open
1	RS macro open
1	DT macro open
1	D2R macro open
1	SSG-EG macro open
---	operator macros × 4 (>=29)
1??	AM macro
1??	AR macro
1??	DR macro
1??	MULT macro
1??	RR macro
1??	SL macro
1??	TL macro
1??	DT2 macro
1??	RS macro
1??	DT macro
1??	D2R macro
1??	SSG-EG macro
---	release points (>=44)
4	volume macro release
4	arp macro release
4	duty macro release
4	wave macro release
4	pitch macro release
4	extra 1 macro release
4	extra 2 macro release
4	extra 3 macro release
4	alg macro release
4	fb macro release
4	fms macro release
4	ams macro release
---	operator release points × 4 (>=44)
4	AM macro release
4	AR macro release
4	DR macro release
4	MULT macro release
4	RR macro release
4	SL macro release
4	TL macro release
4	DT2 macro release
4	RS macro release
4	DT macro release
4	D2R macro release
4	SSG-EG macro release

wavetable

size	description
4	"WAVE" block ID
4	reserved
STR	wavetable name
4	wavetable size
4	wavetable min
4	wavetable max
4??	wavetable data

sample

size	description
4	"SMPL" block ID
4	reserved
STR	sample name
4	length
4	rate
2	volume (<58) or reserved
2	pitch (<58) or reserved
1	depth
- 0: ZX Spectrum overlay drum (1-bit)
- 1: 1-bit NES DPCM (1-bit)
- 4: QSound ADPCM
- 5: ADPCM-A
- 6: ADPCM-B
- 7: X68000 ADPCM
- 8: 8-bit PCM
- 9: BRR (SNES)
- 10: VOX
- 16: 16-bit PCM
1	reserved
2	C-4 rate (>=32) or reserved
4	loop point (>=19) or reserved
- -1 means no loop
???	sample data
- version<58 size is length*2
- version>=58 size is length

pattern

size	description
4	"PATR" block ID
4	reserved
2	channel
2	pattern index
4	reserved
???	pattern data
- size: rows*(4+effectColumns*2)*2
- read shorts in this order:
- note
- octave
- instrument
- volume
- effect and effect data...
STR	pattern name (>=51)

the Furnace instrument format (.fui)

the instrument format is pretty similar to the file format, but it also stores wavetables and samples used by the instrument.

size	description
16	"-Furnace instr.-" format magic
2	format version
2	reserved
4	pointer to instrument data
2	wavetable count
2	sample count
4	reserved
4??	pointers to wavetables
4??	pointers to samples

instrument data follows.

the Furnace wavetable format (.fuw)

similar to the instrument format...

size	description
16	"-Furnace waveta-" format magic
2	format version
2	reserved

wavetable data follows.