curioustorvald/tsvm
1
0
Fork 0
mirror of https://github.com/curioustorvald/tsvm.git synced 2026-06-06 05:28:31 +09:00
Code Issues Packages Projects Releases Wiki Activity

it2taud.py

Browse Source
This commit is contained in:
minjaesong
2026-04-30 14:25:03 +09:00
parent 0a247897e4
commit 376c3c4766
2 changed files with 62 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
TAUD_NOTE_EFFECTS.md
View File

@@ -493,7 +493,7 @@ A tempo slide's memory slot is separate from the set-tempo path and is private t
**Plain.** Sets the global mix bus volume (0..$FF). $00 is silence; $FF is full. The default is $80.
**Compatibility.** ST3's global volume is 0..$40; convert with `taud_v = st3_v × 4`, clamped at $FF. On export, `st3_v = taud_v >> 2`, clamped at $40. IT's global volume is 0..$80; convert with `taud_v = it_v × 2`, clamped at $FF.
**Compatibility.** ST3's global volume is 0..$40; convert with `taud_v = st3_v × 4`, clamped at $FF. On export, `st3_v = taud_v >> 2`, clamped at $40. IT's global volume is 0..$80; convert with `taud_v = it_v × 2`, clamped at $FF. On IT, the very first `V 00` command must be resolved as the song's initial global volume.
**Implementation.** Write the high byte to `global_volume` on the row the command appears. The low byte is reserved. ST3's `kST3NoMutedChannels` rule applies: V on a muted channel is ignored by ST3; for strict-compatible playback Taud follows suit, but new Taud compositions should avoid muting channels that carry global effects.

102
it2taud.py
View File

@@ -90,11 +90,13 @@ EFF_P = 16; EFF_Q = 17; EFF_R = 18; EFF_S = 19; EFF_T = 20
EFF_U = 21; EFF_V = 22; EFF_W = 23; EFF_X = 24; EFF_Y = 25
EFF_Z = 26
# IT effects that recall last non-zero arg (per-effect-private, with cohort exceptions)
# IT effects that recall last non-zero arg (per-effect-private, with cohort exceptions).
# V (Set Global Volume) recalls in IT compat mode — the first V $00 resolves to the
# header's global_vol, not literal 0. Without this, songs starting with V $00 silence.
IT_MEM_EFFECTS = frozenset({
EFF_D, EFF_E, EFF_F, EFF_G, EFF_H, EFF_I, EFF_J,
EFF_K, EFF_L, EFF_N, EFF_O, EFF_P, EFF_Q, EFF_R,
EFF_S, EFF_T, EFF_U, EFF_W, EFF_X, EFF_Y,
EFF_S, EFF_T, EFF_U, EFF_V, EFF_W, EFF_X, EFF_Y,
})
@@ -286,11 +288,13 @@ def _it214_decompress_block(payload: bytes, num_samples: int,
if is_16bit:
init_width = 17
range_count = 16 # escape range size for mid/full forms
range_count = 16 # escape range size in mid form
border_sub = 8 # = range_count / 2; centres escape range on signed midpoint
escape_bits = 4 # bits to read in short-form escape
else:
init_width = 9
range_count = 8
border_sub = 4
escape_bits = 3
width = init_width
@@ -298,55 +302,62 @@ def _it214_decompress_block(payload: bytes, num_samples: int,
out = []
n = 0
mask = (1 << (init_width - 1)) - 1 # 0xFF (8-bit) or 0xFFFF (16-bit)
while n < num_samples:
v = read_bits(width)
if width <= 6:
# Short form: top bit == escape trigger; read escape_bits for new width.
# Reference: cubic.org/itsex.c (Jeffrey Lim, IT author) — no skip-self.
is_data = False
if width < 7:
# Mode A (short): single escape code at v == 1<<(width-1).
if v == (1 << (width - 1)):
width = read_bits(escape_bits) + 1
new_w = read_bits(escape_bits) + 1
width = new_w if new_w < width else new_w + 1 # skip-self
continue
# Else: data, sign-extend from `width` bits.
delta = _sign_extend(v, width)
is_data = True
elif width < init_width:
# Mid form. border = (all-ones mask) >> (init_width - width).
# For 8-bit: 0xFF>>(9-w) → 63 (w=7), 127 (w=8).
# Escape when v > border; new width = v - border directly, no skip-self.
# Reference: cubic.org/itsex.c, OpenMPT ITTools.cpp.
mask = (1 << (init_width - 1)) - 1 # 0xFF (8-bit) or 0xFFFF (16-bit)
border = mask >> (init_width - width)
if v > border:
width = v - border
# Mode B (mid): `range_count` escape codes centred on signed midpoint.
# border = (mask >> (init_width-width)) - border_sub, where border_sub
# = range_count / 2. Reference: libxmp it_compress.c, OpenMPT ITTools.cpp.
# 8-bit: width=7 → border=63-4=59, width=8 → border=127-4=123
# 16-bit: width=7..16 with border_sub=8.
border = (mask >> (init_width - width)) - border_sub
if border < v <= border + range_count:
new_w = v - border
width = new_w if new_w < width else new_w + 1 # skip-self
continue
if v > border + range_count:
v -= range_count # collapse escape range out
delta = _sign_extend(v, width)
is_data = True
else:
# Full form: top bit (bit init_width-1) is escape flag.
# new width = lower bits + 1, no skip-self.
# Mode C (full): top bit (bit init_width-1) signals width change.
top_bit = 1 << (init_width - 1)
if v & top_bit:
width = (v & (top_bit - 1)) + 1
continue
# Else: data is (init_width-1) bits wide, sign-extend from there.
delta = _sign_extend(v, init_width - 1)
is_data = True
# Delta is always cast to the native sample type regardless of current bit-width.
# IT SDK: d1 += (signed char)value — i.e. always 8-bit (or 16-bit) signed cast.
# Upper-half short-form values (v > escape midpoint) are larger *positive* deltas,
# not negatives; _sign_extend(v, width) would wrongly negate them.
delta = _sign_extend(v, init_width - 1)
if is_16bit:
d1 = _wrap16(d1 + delta)
if is_it215:
d2 = _wrap16(d2 + d1)
out.append(d2)
if is_data:
if is_16bit:
d1 = _wrap16(d1 + delta)
if is_it215:
d2 = _wrap16(d2 + d1)
out.append(d2)
else:
out.append(d1)
else:
out.append(d1)
else:
d1 = _wrap8(d1 + delta)
if is_it215:
d2 = _wrap8(d2 + d1)
out.append(d2)
else:
out.append(d1)
n += 1
d1 = _wrap8(d1 + delta)
if is_it215:
d2 = _wrap8(d2 + d1)
out.append(d2)
else:
out.append(d1)
n += 1
return out
@@ -424,7 +435,8 @@ class ITSample:
def parse_samples(data: bytes, h: ITHeader, decompress: bool) -> list:
samples = []
is_it215 = (h.cmwt >= 0x0215)
# IT2.15 compression is signaled PER-SAMPLE via cvt bit 2 (0x04), not globally
# via the file's cwt. Reference: OpenMPT ITTools.cpp, libxmp it_load.c.
for i, ptr in enumerate(h.smp_ptrs):
if ptr == 0 or ptr + 0x50 > len(data):
vprint(f" warning: sample {i+1} pointer {ptr:#x} out of range, skipping")
@@ -465,6 +477,7 @@ def parse_samples(data: bytes, h: ITHeader, decompress: bool) -> list:
vprint(f" warning: '{s.name}' is IT2.14 compressed, --no-decompress → silent")
else:
try:
is_it215 = bool(s.cvt & 0x04)
raw = it214_decompress(data, s.smp_point, s.length,
s.is_16bit, is_it215)
s.sample_data = _normalise_sample(raw, True,
@@ -921,7 +934,8 @@ def encode_effect_it(cmd: int, arg: int, ch: int = 0, row: int = 0) -> tuple:
def resolve_it_recalls(patterns_rows: list, order_list: list,
num_channels: int, link_gef: bool,
old_effects: bool = False) -> None:
old_effects: bool = False,
initial_global_vol: int = 128) -> None:
"""Walk in order, resolve zero-arg recalls per-effect-per-channel.
IT effect memory groups:
@@ -933,10 +947,15 @@ def resolve_it_recalls(patterns_rows: list, order_list: list,
old_effects=True (IT_FLAG_OLD_EFFECTS): E00/F00 are ST3-style stops —
they do NOT recall and are suppressed to TOP_NONE. All other effects
still recall normally even in old_effects mode.
V memory is primed with initial_global_vol so a song-leading V $0000
resolves to the header's global volume, not literal zero.
"""
# last_mem[ch][eff_key] = last_non_zero_arg
# eff_key: integer 1-26 for most effects; we merge cohorts by normalising.
last_mem = [{} for _ in range(num_channels)]
for ch in range(num_channels):
last_mem[ch][EFF_V] = initial_global_vol
# Effects that stop rather than recall when arg=0 in old_effects mode (ST3 compat).
# E/F: pitch slide stop. J: arpeggio stop (J00 = return to normal pitch in ST3).
@@ -1391,7 +1410,8 @@ def assemble_taud(h: ITHeader, samples: list, instruments: list,
# ── Resolve IT recalls ───────────────────────────────────────────────────
vprint(" resolving IT recalls…")
resolve_it_recalls(patterns_rows, h.order_list, 64, h.link_gef,
old_effects=h.old_effects)
old_effects=h.old_effects,
initial_global_vol=h.global_vol)
# ── Check SBx chunk crossing (warn only) ─────────────────────────────────
for pi, (grid, rows) in enumerate(patterns_rows):