furnace/papers/format.md

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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.

header

the header is 32 bytes long.

size description
16 "-Furnace module-" format magic
2 format version
- should be 17 for Furnace 0.4
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
- 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) - 13 channels
- 0x09: Neo Geo (YM2610) - 13 channels
- bit 6 enables alternate mode:
- 0x42: Genesis extended - 13 channels
- 0x47: C64 (6581) - 3 channels
- 0x49: Neo Geo extended - 16 channels
- bit 7 for non-DefleMask chips:
- 0x80: AY-3-8910 - 3 channels
- 0x82: YM2151 alone - 8 channels
- 0x83: YM2612 alone - 6 channels
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)
??? song name
??? song author
24 reserved for compatibility flags
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

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
??? 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
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)

wavetable

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

sample

size description
4 "SMPL" block ID
4 reserved
??? sample name
4 length
4 rate
2 volume
2 pitch
1 depth
7 reserved
2?? sample data (always 16-bit)

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...

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.