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 15 for Furnace 0.3
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2 | reserved
4 | song info pointer
8 | reserved
# song info
size | description
-----|------------------------------------
4 | "INFO" block ID
4 | reserved
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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
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| - possible soundchips:
| - 0x00: end of list
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| - 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
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
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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
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??? | effect columns
| - size=channels
# instrument
size | description
-----|------------------------------------
4 | "INST" block ID
4 | reserved
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2 | format version (see header)
1 | instrument type
| - 0: standard
| - 1: FM
| - 2: Game Boy
| - 3: C64
| - 4: Amiga/sample
1 | reserved
??? | instrument name
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--- | **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 | volume macro loop
4 | arp macro loop
4 | duty macro loop
4 | wave macro loop
1 | arp macro mode
3 | reserved
4?? | volume macro
4?? | arp macro
4?? | duty macro
4?? | wave macro
# wavetable
size | description
-----|------------------------------------
4 | "WAVE" block ID
4 | reserved
??? | wavetable name
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4 | wavetable size
4 | wavetable min
4 | wavetable max
4?? | wavetable data
# sample
size | description
-----|------------------------------------
4 | "SMPL" block ID
4 | reserved
??? | sample name
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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
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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...