Sound module: Expression on every part, kept when a part's instrument is made again

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Sound module: Expression (CC11) works on instrument parts as well as SoundFont parts, and a part keeps it when its instrument is made again, by a bank change or All Sound Off.
+
 ## 0.1.2.dev0
 
 - Wake word: the app listens through medialink.wakeword and tflite.

lib/soundmodule/engine.py

@@ -31,7 +31,9 @@
 own 0-127 scale. Volume (CC7) reaches a SoundFont part as CC7, which plays
 it as the square law GM modules use (40 log10 of CC7/127 in dB, as
 Expression), and pan (CC10) its Pan macro; on an instrument part both set
-its level and pan in the mixer.
+its level and pan in the mixer. Expression (CC11) is the same square law on
+every part, multiplied with volume, and a part keeps it when its instrument is
+made again (a bank or program change to another instrument, or All Sound Off).
 The sustain pedal (CC64) holds notes for every part, and Reset All
 Controllers (121) also puts Expression (CC11) back to 127 and the mod wheel
 and channel pressure to 0, as GM's RP-015 asks.
@@ -154,6 +156,7 @@
 
 DEFAULT_VOLUME = 100
 DEFAULT_PAN = 64
+DEFAULT_EXPRESSION = 127
 # The soundfont instruments' macros that CC7 and CC10 drive.
 VOLUME_MACRO, PAN_MACRO = 0, 4
 DEFAULT_REVERB = 40  # GM Level 1's power-on reverb send; chorus is 0
@@ -306,6 +309,7 @@ def reset(self):
         self.bank_msb = 0
         self.bank_lsb = 0
         self.volume = DEFAULT_VOLUME
+        self.expression = DEFAULT_EXPRESSION
         self.pan = DEFAULT_PAN
         self.sustain = False
         self.held = set()
@@ -584,18 +588,21 @@ def _select(self, part):
             if index in inst.patches:
                 inst.program_change(index)
             inst.control_change(CC_VOLUME, part.volume)
+            inst.control_change(CC_EXPRESSION, part.expression)
             inst.set_macro(PAN_MACRO, part.pan)
         else:
             if part.bank_lsb in inst.patches:
                 inst.program_change(part.bank_lsb)
             self._level(part)
 
     def _level(self, part):
-        """An instrument part's volume and pan, on its mixer voice."""
+        """An instrument part's volume, expression and pan, on its mixer
+        voice: volume and expression multiply, and the product is squared,
+        as a SoundFont part plays them."""
         if not self._own_voice(part):
             return
         voice = self.mixer.voice[part.channel]
-        v = part.volume / 127.0
+        v = part.volume / 127.0 * part.expression / 127.0
         voice.level = PART_LEVEL * v * v
         try:
             voice.panning = max(-1.0, min(1.0, (part.pan - 64) / 63.0))
@@ -771,6 +778,13 @@ def control(self, part, cc, value):
                     inst.control_change(CC_VOLUME, value)
                 else:
                     self._level(part)
+        elif cc == CC_EXPRESSION:
+            part.expression = value
+            if inst is not None:
+                if part.inst_name in (MELODIC, DRUMS):
+                    inst.control_change(CC_EXPRESSION, value)
+                else:
+                    self._level(part)
         elif cc == CC_PAN:
             part.pan = value
             if inst is not None:
@@ -874,11 +888,14 @@ def reset_controllers(self, part):
         self._release_sustained(part)
         part.bend = BEND_CENTER
         part.rpn = RPN_NULL
+        part.expression = DEFAULT_EXPRESSION
         inst = part.inst
         if inst is not None:
             inst.pitch_bend(BEND_CENTER)
-            if part.inst_name in (MELODIC, DRUMS):
-                inst.control_change(CC_EXPRESSION, 127)
+            if part.inst_name not in (MELODIC, DRUMS):
+                self._level(part)
+            else:
+                inst.control_change(CC_EXPRESSION, DEFAULT_EXPRESSION)
                 inst.control_change(CC_MOD_WHEEL, 0)
                 if hasattr(inst, "channel_pressure"):
                     inst.channel_pressure(0)

tests/engine_contract.py

@@ -34,7 +34,8 @@
 PLANTS = ("bank-ignored", "lsb-ignored", "eager-bank", "macro-shift", "level-linear", "identity-wrong",
           "identity-any-device", "tally-final", "pipe-drops-peek", "frames-miscounted",
           "rpn-ignored", "rpn-null-ignored", "rpn-lsb-kept", "reset-keeps-bend", "reset-keeps-expression",
-          "fixed-range-unscaled", "reset-keeps-rpn", "volume-as-macro", "sends-last-wins", "fill-skipped")
+          "fixed-range-unscaled", "reset-keeps-rpn", "volume-as-macro", "sends-last-wins", "fill-skipped",
+          "expression-passthrough", "expression-forgotten", "expression-level-ignored")
 
 RESULTS = [0, 0]
 
@@ -239,6 +240,40 @@ def check_soundfont_volume():
           "ccs %r, macros %r" % (inst.ccs, inst.macros))
 
 
+def check_expression():
+    m, made = module()
+    select(m, 2, engine.BANK_INSTRUMENTS, 0, 0)
+    m.feed(bytes((0xB2, 7, 64, 0xB2, 11, 64)))
+    voice = m.mixer.voice[2]
+    want = engine.PART_LEVEL * (64 / 127.0 * 64 / 127.0) ** 2
+    check("CC11 and CC7 multiply, squared, on an instrument part's level", abs(voice.level - want) < 1e-6,
+          "%r, not %r" % (voice.level, want))
+    m.feed(bytes((0xB2, 121, 0)))
+    want = engine.PART_LEVEL * (64 / 127.0) ** 2
+    check("Reset All Controllers puts an instrument part's Expression back", abs(voice.level - want) < 1e-6,
+          "%r, not %r" % (voice.level, want))
+    m.feed(bytes((0xB2, 11, 32, 0xB2, 120, 0)))
+    want = engine.PART_LEVEL * (64 / 127.0 * 32 / 127.0) ** 2
+    check("an instrument part keeps its Expression through All Sound Off", abs(voice.level - want) < 1e-6,
+          "%r, not %r" % (voice.level, want))
+
+    m, made = module()
+    m.feed(bytes((0x90, 60, 100, 0xB0, 11, 32)))
+    inst = m.parts[0].inst
+    check("CC11 reaches a SoundFont part as CC11", (11, 32) in inst.ccs, repr(inst.ccs))
+    inst.ccs = []
+    m.feed(bytes((0xB0, 120, 0)))
+    check("a SoundFont part keeps its Expression through All Sound Off", (11, 32) in inst.ccs, repr(inst.ccs))
+    select(m, 0, engine.BANK_INSTRUMENTS, 0, 0)
+    select(m, 0, 0, 0, 4)
+    again = made[-1]
+    check("a SoundFont part made again has its Expression", again is not inst and (11, 32) in again.ccs,
+          repr(again.ccs))
+    m.feed(bytes((0xF0, 0x7E, 0x7F, 0x09, 0x01, 0xF7)))
+    check("GM System On puts Expression back to 127", m.parts[0].expression == 127 and again.ccs[-1] == (11, 127),
+          "%r, %r" % (m.parts[0].expression, again.ccs[-2:]))
+
+
 def check_identity():
     replies = []
     m, made = module(send=replies.append)
@@ -552,6 +587,35 @@ def reset_controllers(self, part):
                 part.inst.pitch_bend(engine.BEND_CENTER)
 
         M.reset_controllers = reset_controllers
+    elif name == "expression-passthrough":
+        old = M.control
+
+        def control(self, part, cc, value):
+            if cc == engine.CC_EXPRESSION:
+                if part.inst is not None:
+                    part.inst.control_change(cc, value)
+                return
+            old(self, part, cc, value)
+
+        M.control = control
+    elif name == "expression-forgotten":
+        old = M._select
+
+        def _select(self, part):
+            kept = part.expression
+            part.expression = engine.DEFAULT_EXPRESSION
+            old(self, part)
+            part.expression = kept
+
+        M._select = _select
+    elif name == "expression-level-ignored":
+        def _level(self, part):
+            if self._own_voice(part):
+                v = part.volume / 127.0
+                self.mixer.voice[part.channel].level = engine.PART_LEVEL * v * v
+                self.mixer.voice[part.channel].panning = max(-1.0, min(1.0, (part.pan - 64) / 63.0))
+
+        M._level = _level
     elif name == "fixed-range-unscaled":
         M._wheel = lambda self, part: part.bend
     elif name == "reset-keeps-rpn":
@@ -589,6 +653,7 @@ def main(argv):
     check_macro_ccs()
     check_volume_pan()
     check_soundfont_volume()
+    check_expression()
     check_identity()
     check_tally()
     check_rpn()