taud bugfix

mod2taud.py

@@ -182,6 +182,26 @@ def parse_mod(data: bytes):
                 inst   = (b0 & 0xF0) | ((b2 >> 4) & 0x0F)
                 effect = b2 & 0x0F
                 arg    = b3
+                # MT-style PT-strict cell rewrites (LoaderMOD.cpp:354-365):
+                # PT does not recall arg for portamento up/down (1xx, 2xx) or
+                # volume slide (Axx); the literal arg is read every tick. The
+                # vol-slide nibbles in 5xx/6xx likewise take literal args, with
+                # the recalled state living in the porta/vibrato side. So a
+                # zero-arg cell decays to a no-slide variant: 1/2/A drop to
+                # no-op, 5 collapses to bare tone-porta (3), 6 to bare vibrato
+                # (4). Without this, resolve_pt_recalls would back-fill these
+                # zero args from the cohort memory and produce a continuous
+                # slide where PT plays a single-row swell (canonical bug:
+                # GSLINGER ord 0x03 ch1 — `5 01` on r30/r38 with `5 00` on the
+                # rest, was fading 24→0 in 5 rows instead of stair-stepping
+                # 24→14 across 16 rows).
+                if arg == 0:
+                    if effect in (0x1, 0x2, 0xA):
+                        effect = 0x0
+                    elif effect == 0x5:
+                        effect = 0x3
+                    elif effect == 0x6:
+                        effect = 0x4
                 cell = grid[ch][r]
                 cell.period     = period
                 cell.inst       = inst

terranmon.txt

@@ -2394,8 +2394,8 @@ TODO:
         when no V column is present. Engine + all four `*2taud` converters
         updated; legacy `.taud` files (byte 196 == 0) fall back to the
         previous "row volume default = 63" behaviour.
-    [ ] Physical Presence order 0x1F chn 2: note cuts unexpectedly fast?
-        GSLINGER order 0x03 chn 1: L 0100 fades unexpectedly fast?
+    [x] physical_presence order 0x1F chn 2: note cuts unexpectedly fast — engine fix
+    [x] GSLINGER order 0x03 chn 1: L 0100 fades unexpectedly fast? — converter fix
 
 TODO - list of demo songs that MUST ship with Microtone:
     * 4THSYM (rename to Fourth Symmetriad) — excellent piece for demonstrating NNAs and filter envelopes

tsvm_core/src/net/torvald/tsvm/peripheral/AudioAdapter.kt

@@ -2145,11 +2145,28 @@ class AudioAdapter(val vm: VM) : PeriBase(VM.PERITYPE_SOUND) {
             // mirroring G's behaviour — the L command continues the porta started by an earlier G.
             val toneG = (row.effect == EffectOp.OP_G || row.effect == EffectOp.OP_L)
             when (row.note) {
-                // No note but an instrument byte is present: latch the instrument so
-                // the *next* note-only trigger picks up the right sample. Trackers
-                // call this an "instrument-only retrigger"; in MOD/S3M/IT the sample
-                // keeps playing, but the channel's instrument reference advances.
-                0xFFFF -> { if (row.instrment != 0) voice.instrumentId = row.instrment }
+                // No note but an instrument byte is present: latch the instrument and
+                // re-seed the channel volume from the new sample's Default Note Volume.
+                // PT, FT2, IT and Schism all do this — pt2_replayer.c:1086 writes
+                // ch->n_volume = s->volume on every sample-byte row regardless of note;
+                // ft2_replayer.c:1431-1434 calls resetVolumes(ch) when (note==0 && inst>0);
+                // schism csf_instrument_change writes chan->volume = psmp->volume whenever
+                // inst_column is set. Without this, a MOD pattern that runs continuous
+                // volume slides while re-asserting the sample byte each row (e.g.
+                // physical_presence ord 0x1F ch2: every row carries `... 1E A0F/A09/A02`)
+                // silences after the first row because the slide saturates at 0 and there's
+                // nothing to lift the volume back up before the next slide starts.
+                0xFFFF -> {
+                    if (row.instrment != 0) {
+                        voice.instrumentId = row.instrment
+                        val seedVol = rowVolumeFromDefault(instruments[voice.instrumentId])
+                        voice.channelVolume = seedVol
+                        voice.rowVolume = seedVol
+                        voice.keyOff = false
+                        voice.noteFading = false
+                        voice.fadeoutVolume = 1.0
+                    }
+                }
                 // Key-off: release sustain; envelope walks past the sustain point and the fadeout
                 // begins (foreground-voice fade path at line ~2380). The voice deactivates when
                 // fadeoutVolume reaches 0, or immediately if FT2-mode fadeStep == 0. Setting