fix: reduce MIDI playback crackling (no per-note prog reload, underrun-proof render loop, gentle stopAll)

app/static/js/services/soundfontPlayer.js

@@ -1,6 +1,6 @@
 (function () {
     const RENDER_BLOCK = 512;
-    const QUEUE_TARGET = 4;
+    const QUEUE_TARGET = 8;
     let _audioCtx = null;
     let _fluidModule = null;
     let _synthPtr = null;
@@ -419,7 +419,11 @@
                     }
                     // Program change at note time, not call time — ensures correct
                     // instrument for each item regardless of processing order.
-                    if (synthEngine || program !== undefined) {
+                    // Skip if the channel already has this exact instrument (avoids
+                    // per-note soundfont reloads that cause audible crackle/glitches).
+                    var cachedCh = _channels[ch];
+                    var progAlreadySet = cachedCh && cachedCh.program === finalProg && cachedCh.bank === finalBank && cachedCh.sfId === finalSfId;
+                    if ((synthEngine || program !== undefined) && !progAlreadySet) {
                         var sfHandle = finalSfId ? _sfHandleMap.get(finalSfId) : undefined;
                         if (sfHandle !== undefined) {
                             try {
@@ -429,8 +433,11 @@
                             try { _fluidModule._fluid_synth_bank_select(_synthPtr, ch, finalBank); } catch (e) {}
                             try { _fluidModule._fluid_synth_program_change(_synthPtr, ch, finalProg); } catch (e) {}
                         }
+                        if (!_channels[ch]) _channels[ch] = {};
+                        _channels[ch].bank = finalBank;
+                        _channels[ch].program = finalProg;
+                        _channels[ch].sfId = finalSfId;
                     }
-                    console.log("[SonicSF] noteOn ch:", ch, "pitch:", midiPitch, "vel:", midiVel);
                     _fluidModule._fluid_synth_noteon(_synthPtr, ch, midiPitch, midiVel);
                     var noteMapKey = (_origChannel !== undefined ? _origChannel : 0) + ':' + midiPitch;
                     if (!_activeNotes[noteMapKey]) _activeNotes[noteMapKey] = [];
@@ -521,7 +528,6 @@
             if (_initialized && _fluidModule) {
                 for (var ch = 0; ch < 16; ch++) {
                     try { _fluidModule._fluid_synth_all_notes_off(_synthPtr, ch); } catch (e) {}
-                    try { _fluidModule._fluid_synth_all_sounds_off(_synthPtr, ch); } catch (e) {}
                 }
             }
             while (_scheduledNotes.length > 0) {
@@ -562,10 +568,17 @@
         var leftPtr = _leftBufPtr;
         var rightPtr = _rightBufPtr;
         var block = RENDER_BLOCK;
-        var queueDepth = 0;
         var maxQueue = QUEUE_TARGET;
+        var queueDepth = 0;
+
+        // Worklet reports consumed frames so the queue depth stays accurate and
+        // we never underrun (silence gaps → crackle) while the main thread is busy.
+        node.port.onmessage = function (e) {
+            if (e.data && e.data.type === 'CONSUMED' && e.data.n) {
+                queueDepth = Math.max(0, queueDepth - e.data.n);
+            }
+        };
 
-        var _dbgPeak = 0;
         function pushFrame() {
             if (!Module || !synth || !node) return;
             try {
@@ -576,18 +589,6 @@
                 Module._fluid_synth_write_float(synth, block, leftPtr, 0, 1, rightPtr, 0, 1);
                 var leftArr = new Float32Array(Module.HEAPF32.subarray(lpb, lpb + block));
                 var rightArr = new Float32Array(Module.HEAPF32.subarray(rpb, rpb + block));
-                var peak = 0;
-                var avg = 0;
-                for (var si = 0; si < leftArr.length; si++) {
-                    var abs = leftArr[si] > 0 ? leftArr[si] : -leftArr[si];
-                    if (abs > peak) peak = abs;
-                    avg += abs;
-                }
-                avg /= leftArr.length;
-                if (!_dbgPeak) {
-                    _dbgPeak = 1;
-                    console.log("[SonicSF] FRAME peak:", peak.toFixed(6), "avg:", avg.toFixed(8), "gain check:", Module._fluid_synth_get_gain ? Module._fluid_synth_get_gain(synth) : 'N/A');
-                }
                 node.port.postMessage({ type: 'PCM', L: leftArr, R: rightArr }, [leftArr.buffer, rightArr.buffer]);
                 queueDepth++;
             } catch (e) { console.warn("[SonicSF] pushFrame error:", e); }
@@ -602,10 +603,9 @@
             for (var i = 0; i < needed; i++) {
                 pushFrame();
             }
-            queueDepth = Math.max(0, queueDepth - 1);
         }
 
-        _renderTimer = setInterval(fillLoop, Math.max(8, (block / _audioCtx.sampleRate) * 1000 * 0.75));
+        _renderTimer = setInterval(fillLoop, Math.max(4, (block / _audioCtx.sampleRate) * 1000 * 0.5));
     }
 
     function _stopRenderLoop() {

app/static/js/worklets/fluidsynth-bridge.js

@@ -29,14 +29,10 @@ class FluidSynthBridge extends AudioWorkletProcessor {
       si++;
       if (si >= qL[fi].length) { fi++; si = 0; }
     }
-    if (fi > 0) { this.leftQ.splice(0, fi); this.rightQ.splice(0, fi); }
-    if (this.called % 50 === 0) {
-      var pk = 0;
-      for (var j = 0; j < len; j++) {
-        var v = out[0][j] > 0 ? out[0][j] : -out[0][j];
-        if (v > pk) pk = v;
-      }
-      if (pk > 0) console.log('[FluidSynth:bridge] process #' + this.called + ' peak:' + pk.toFixed(6) + ' q:' + qL.length);
+    if (fi > 0) {
+      this.leftQ.splice(0, fi);
+      this.rightQ.splice(0, fi);
+      this.port.postMessage({ type: 'CONSUMED', n: fi });
     }
     return true;
   }