Skip to content

Instantly share code, notes, and snippets.

@jangler jangler/it2fss.py
Created Mar 15, 2014

Embed
What would you like to do?
#!/usr/bin/env python
"""
it2fss.py, version 0.2
----------------------
Python 3 only.
This script converts single-channel Impulse Tracker module into a FSS text file
for use with fsound.exe. No effects commands are supported. Needless to say,
this program only looks at pattern data and initial speed & tempo;
instruments/samples/etc aren't supported in any capacity.
To make white noise, use a note value out of fsound's supported octave range
(for example, C-0).
If you find a bug in this program, contact me in IRC (Jangler on irc.esper.net)
or by email (brandon *at* jangler *dot* info).
Version history
---------------
* 0.2: Fixed a bug that occurred when translating a single IT note into
multiple FSS notes.
* 0.1: Initial creation of program.
"""
from sys import argv, stderr, version_info
def die(msg):
if isinstance(msg, BaseException):
msg = str(msg)
stderr.write(str(msg) +'\n')
exit(1)
if version_info.major < 3:
die('python3 only!')
from collections import namedtuple
from math import floor, log2
from struct import unpack_from
if len(argv) == 2:
MODULE = argv[1]
else:
die('Usage: {} MODULE'.format(argv[0]))
Module = namedtuple('Module', ('speed', 'tempo', 'orders', 'patterns'))
NOTE_NAMES = ['a', 'A', 'b', 'c', 'C', 'd', 'D', 'e', 'f', 'F', 'g', 'G']
VALUE_NAMES = ['f', '8', '4', '2', '1']
def note_format(note, rows):
lengths = []
while rows > 0:
power = min(4, floor(log2(rows)))
lengths.append(VALUE_NAMES[power])
rows -= 2**power
strings = []
for length in lengths:
if note is not None:
if note < 120:
fs_note = note - 9
octave = fs_note // 12
if 1 <= octave <= 7:
name = NOTE_NAMES[fs_note % 12]
strings.append('{}{}{}'.format(name, octave, length))
else:
strings.append('x-' + length)
else:
strings.append('r-' + length)
else:
strings.append('r-' + length)
if strings:
return '\n'.join(strings) + '\n'
return ''
def read_orders(data):
ordnum = unpack_from('H', data, 0x20)[0]
return unpack_from('B' * ordnum, data, 0xC0)
def pattern_offsets(data):
ordnum, insnum, smpnum, patnum = unpack_from('HHHH', data, 0x20)
offset = 0xC0 + ordnum + insnum * 4 + smpnum * 4
return unpack_from('I' * patnum, data, offset)
def read_pattern(data, offset):
_, rows = unpack_from('HH', data, offset)
offset += 8
prev_maskvar, prev_note, prev_ins = ([0] * 64 for i in range(3))
prev_vol, prev_cmd, prev_cmdval = ([0] * 64 for i in range(3))
items = [[None for y in range(rows)] for x in range(4)]
for row in range(rows):
while True:
channelvariable = unpack_from('B', data, offset)[0]
offset += 1
if channelvariable == 0:
break # end of row
channel = (channelvariable - 1) & 63
if channelvariable & 128:
maskvar = unpack_from('B', data, offset)[0]
offset += 1
else:
maskvar = prev_maskvar[channel]
prev_maskvar[channel] = maskvar
if maskvar & 1:
note = unpack_from('B', data, offset)[0]
prev_note[channel] = note
offset += 1
else:
note = None
if maskvar & 2:
ins = unpack_from('B', data, offset)[0]
prev_ins[channel] = ins
offset += 1
else:
ins = None
if maskvar & 4:
vol = unpack_from('B', data, offset)[0]
prev_vol[channel] = vol
offset += 1
else:
vol = None
if maskvar & 8:
cmd, cmdval = unpack_from('BB', data, offset)
prev_cmd[channel], prev_cmdval[channel] = cmd, cmdval
offset += 2
else:
cmd, cmdval = None, None
if maskvar & 16:
note = prev_note[channel]
if maskvar & 32:
ins = prev_ins[channel]
if maskvar & 64:
vol = prev_vol[channel]
if maskvar & 128:
cmd = prev_cmd[channel]
cmdval = prev_cmdval[channel]
if channel < 4:
items[channel][row] = note
return items
def read_patterns(data):
offsets = pattern_offsets(data)
patterns = []
for offset in offsets:
pattern = read_pattern(data, offset)
patterns.append(pattern)
return tuple(patterns)
def read_module(filename):
try:
with open(filename, 'rb') as f:
data = f.read()
except BaseException as ex:
die(ex)
if data[:4].decode('ascii') != 'IMPM':
die("Invalid IT module: '{}'".format(filename))
speed, tempo = unpack_from('BB', data, 0x32)
orders = read_orders(data)
patterns = read_patterns(data)
return Module(speed, tempo, orders, patterns)
def convert(module, filename):
try:
outfile = open(filename, 'w')
except BaseException as ex:
die(ex)
outfile.write('{}\n\n'.format(2500 // module.tempo * module.speed))
outfile.write('> generated by it2fss.py\n\n')
item = 255
length = 0
for order in (x for x in module.orders if x != 255):
pattern = module.patterns[order]
outfile.write('> pattern {}\n'.format(order))
for row in range(len(pattern[0])):
cur_item = pattern[0][row]
if cur_item is not None and cur_item != item:
outfile.write(note_format(item, length))
length = 0
item = cur_item
length += 1
outfile.write('\n')
if item:
outfile.write(note_format(item, length))
outfile.close()
module = read_module(MODULE)
convert(module, MODULE + '.fss')
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.