Add pitch bend scaling for MPE slides + fix compose_pitch_bend overflow

- Add bend_scale setting (default 1.0) for adjusting pitch bend intensity
- Fix compose_pitch_bend() overflow bug: max bend (16384) wrapped to min
- Add helpful comments: LinnStrument Pitch Quantize must be OFF for smooth slides

Author: zitongcharliedeng

src/core.py

@@ -957,6 +957,15 @@ def cb_midi_in(self, data, timestamp, force_channel=None):
 
             skip = False
             if msg == 14:
+                # Scale pitch bend for mech layout (bend_scale in settings.ini)
+                # Especially useful for whole-tone slides - smooth bends let you
+                # reliably hit semitones in between the whole tones
+                # NOTE: LinnStrument Pitch Quantize must be OFF for smooth slides
+                # NOTE: Synth must have MPE enabled for per-note slides
+                bend_val = decompose_pitch_bend((data[1], data[2]))
+                bend_val *= self.options.bend_scale
+                data[1], data[2] = compose_pitch_bend(bend_val)
+                
                 if self.is_split():
                     # experimental: ignore pitch bend for a certain split
                     split_chan = self.notes[ch].split
@@ -1386,6 +1395,11 @@ def __init__(self):
         self.options.y_bend = get_option(
             opts, "y_bend", DEFAULT_OPTIONS.y_bend
         )
+        
+        # Pitch bend scaling for mech layout (adjust if slides are too slow/fast)
+        self.options.bend_scale = get_option(
+            opts, "bend_scale", DEFAULT_OPTIONS.bend_scale
+        )
 
         # self.options.mpe = get_option(
         #     opts, "mpe", DEFAULT_OPTIONS.mpe

src/settings.py

@@ -96,6 +96,9 @@ class Settings:
 
     bend_range: int = 24
 
+    # Pitch bend scaling for mech layout (1.0 = no scaling, 2.0 = double)
+    bend_scale: float = 1.0
+
     row_offset: int = 5
     column_offset: int = 2
     base_offset: int = 4

src/util.py

@@ -108,7 +108,12 @@ def decompose_pitch_bend(pitch_bend_bytes):
     return pitch_bend_norm
 
 def compose_pitch_bend(pitch_bend_norm):
-    pitch_bend_value = int((pitch_bend_norm + 1.0) * 8192)
+    # Clamp input to valid range
+    pitch_bend_norm = max(-1.0, min(1.0, pitch_bend_norm))
+    # Scale to 0-16383 (14-bit MIDI pitch bend range)
+    # Using 8191.5 and round() to correctly map: -1.0->0, 0.0->8192, 1.0->16383
+    pitch_bend_value = int(round((pitch_bend_norm + 1.0) * 8191.5))
+    pitch_bend_value = max(0, min(16383, pitch_bend_value))  # Ensure valid range
     pitch_bend_bytes = [pitch_bend_value & 0x7F, (pitch_bend_value >> 7) & 0x7F]
     return pitch_bend_bytes