From Atariki
RMT 1.x module format
--------------------------------
header struct
=============
offset type desc
------ ---- ----
00 DWORD header string 'RMT4' or 'RMT8'
04 BYTE track len ($00 means 256)
05 BYTE song speed
06 BYTE player freq
07 BYTE format version number ($01 for player routine 1.x compatible format)
08 WORD pointer to instrument pointers table
0a WORD pointer to track pointers table (lo)
0c WORD pointer to track pointers table (hi)
0e WORD pointer to tracks list (SONG)
instrument struct
=================
offset type desc
------ ---- ----
00 BYTE tlen (pointer to end of table of notes)
01 BYTE tgo (pointer to loop of table of notes)
02 BYTE elen (pointer to end of envelope)
03 BYTE ego (pointer to loop of envelope)
04 BYTE tspd (bit 0-5), tmode (bit 6), ttype (bit 7)
05 BYTE audctl
06 BYTE vslide
07 BYTE vmin(bit 4-7)
08 BYTE delay ($00 for no vibrato & no fshift)
09 BYTE vibrato
0a BYTE fshift
0b BYTE unused
0c table of notes
? envelope
TABLE OF NOTES struct
=====================
BYTE note or frequence (according to the ttype)
ENVELOPE struct
===============
BYTE volume (bit 0-3 left channel) (bits 4-7 right channel
(in RMT4 it's the same as bits 0-3))
BYTE portamento (bit 0), distortion(bit 1-3),
command (bit 4-6), filter (bit 7)
BYTE XY
TRACK struct
============
BYTE
bit 0-5 note
bit 6-7 volume(HI) or pause(1-3 beats) or special
if note is $00-$3c:
BYTE
bit 0-1 volume(LO)
bit 2-7 instrument number
if note is $3d:
BYTE
bit 0-1 volume(LO) volume only
if note is $3e:
bit 6-7 pause
if pause is $01-$03: pause 1-3 beats
if pause is $00: next byte pause 1-255 beats
if note is $3f:
if bit 6-7 is zero: next byte speed $01-$ff
if bit 6 is zero, 7 is set up: next byte is track jump pointer
(go to $00-$ff from the begin of track data)
if bit 6-7 is set up: END of track
INSTRUMENTS TABLE
=================
WORD ptr_instr0
WORD ptr_instr1
WORD ptr_instr3
...
TRACKS TABLE (LO)
=================
BYTE lowbyte_of_ptr_track0
BYTE lowbyte_of_ptr_track1
BYTE lowbyte_of_ptr_track2
...
TRACKS TABLE (HI)
=================
BYTE highbyte_of_ptr_track0
BYTE highbyte_of_ptr_track1
BYTE highbyte_of_ptr_track2
...
TRACK LIST struct (SONG)
========================
BYTE tracknumL1,tracknumL2,tracknumL3,tracknumL4,[tracknumR1,..,tracknumR4]
BYTE tracknumL1,tracknumL2,tracknumL3,tracknumL4,[tracknumR1,..,tracknumR4]
BYTE tracknumL1,tracknumL2,tracknumL3,tracknumL4,[tracknumR1,..,tracknumR4]
...
if tracknum is FF, then empty track is used
if tracknumL1 is FE, then gotoline(BYTE)=tracknumL2, goto_pointer(WORD)=(tracknumL3,4)
Note: gotoline(BYTE) is not used in player (but tracker uses it)
