Merge ps-w9-t2-modes: S15/S16 sampling modes + pitch engines

src/vst/reasampler_processor.cpp

@@ -43,6 +43,13 @@ constexpr double kSustainLevel = 1.0;
 constexpr double kReleaseSeconds = 0.060;
 constexpr std::size_t kMaxVoices = 16;
 
+// S16 Preserve-mode voice cap: a Preserve voice runs a per-voice OLA pitch shifter and is
+// materially heavier than a Varispeed voice. Below the Varispeed polyphony bound so a chord of
+// Preserve notes stays within the RT budget; a Preserve note-on past the cap is dropped rather
+// than glitching (Varispeed notes are unaffected). Set from the measured/estimated per-voice
+// cost — see the handoff CPU note. 8 is a conservative half of kMaxVoices pending DAW profiling.
+constexpr std::size_t kPreserveVoiceCap = 8;
+
 AdsrParams tier0Adsr(double sampleRate) {
     const double sr = sampleRate > 0.0 ? sampleRate : 44100.0;
     AdsrParams p;
@@ -375,8 +382,15 @@ std::string ReaSamplerProcessor::reloadFromBank() {
         }
 
         if (haveKeymap) {
+            // Preserve OLA window in OUTPUT frames from the host sample rate (kPreserveWindowMs).
+            // Every voice's shifter is pre-sized to this off-thread here, so process()-time
+            // note-on never allocates. Floored at 2 so a valid window is always a real ring.
+            std::int64_t preserveWindow = static_cast<std::int64_t>(
+                kPreserveWindowMs * (sampleRate_ > 0.0 ? sampleRate_ : 44100.0) / 1000.0 + 0.5);
+            if (preserveWindow < 2) preserveWindow = 2;
             built = std::make_unique<LoadedInstrument>(
-                std::move(km), kMaxVoices, tier0Adsr(sampleRate_), gen);
+                std::move(km), kMaxVoices, tier0Adsr(sampleRate_), gen, kPreserveVoiceCap,
+                preserveWindow);
         }
     }