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.

notice: GitHub's Markdown formatter may break on this file as it doesn't seem to treat tables correctly.

information

files may be zlib-compressed, but Furnace accepts uncompressed files as well.

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:

66: Furnace dev66
65: Furnace dev65
64: Furnace dev64
63: Furnace dev63
62: Furnace dev62
61: Furnace dev61
60: Furnace dev60
59: Furnace dev59
58: Furnace dev58
57: Furnace dev57
54: Furnace 0.5.8
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 CD (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 CD 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: Neo Geo (YM2610) - 14 channels
     |     - 0xa6: Neo Geo extended (YM2610) - 17 channels
     |     - 0xa7: OPLL drums (YM2413) - 11 channels
     |     - 0xa8: Atari Lynx - 4 channels
     |     - 0xa9: SegaPCM (for Deflemask Compatibility) - 5 channels
     |     - 0xaa: MSM6295 - 4 channels
     |     - 0xab: MSM6258 - 1 channel
     |     - 0xac: Commander X16 (VERA) - 17 channels
     |     - 0xb0: Seta/Allumer X1-010 - 16 channels
     |     - 0xde: YM2610B extended - 19 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
 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
  1  | stop portamento on note off (>=62) or reserved
  1  | continuous vibrato (>=62) or reserved
  1  | broken DAC mode (>=64) or reserved
  1  | one tick cut (>=65) or reserved
  1  | instrument change allowed during porta (>=66) or reserved
  1  | reserved
 4?? | pointers to instruments
 4?? | pointers to wavetables
 4?? | pointers to samples
 4?? | pointers to patterns
 ??? | orders
     | - a table of bytes
     | - size=channels*ordLen
     | - read orders then 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
     | - this is either 2 or 4, and is ignored on non-OPL systems.
     | - always read 4 ops regardless of this value.
  1  | OPLL preset (>=60) or reserved
     | - 0: custom
     | - 1-15: pre-defined patches
     | - 16: drums (compatibility only!)
  2  | 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
 --- | **extended op macro headers** × 4 (>=61)
  4  | DAM macro length
  4  | DVB macro length
  4  | EGT macro length
  4  | KSL macro length
  4  | SUS macro length
  4  | VIB macro length
  4  | WS macro length
  4  | KSR macro length
  4  | DAM macro loop
  4  | DVB macro loop
  4  | EGT macro loop
  4  | KSL macro loop
  4  | SUS macro loop
  4  | VIB macro loop
  4  | WS macro loop
  4  | KSR macro loop
  4  | DAM macro release
  4  | DVB macro release
  4  | EGT macro release
  4  | KSL macro release
  4  | SUS macro release
  4  | VIB macro release
  4  | WS macro release
  4  | KSR macro release
  1  | DAM macro open
  1  | DVB macro open
  1  | EGT macro open
  1  | KSL macro open
  1  | SUS macro open
  1  | VIB macro open
  1  | WS macro open
  1  | KSR macro open
 --- | **extended op macros** × 4 (>=61)
 1?? | DAM macro
 1?? | DVB macro
 1?? | EGT macro
 1?? | KSL macro
 1?? | SUS macro
 1?? | VIB macro
 1?? | WS macro
 1?? | KSR macro
 --- | **OPL drums mode data** (>=63)
  1  | fixed frequency mode
  1  | reserved
  2  | kick frequency
  2  | snare/hi-hat frequency
  2  | tom/top frequency

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.

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