From 1972add3099688ea2d26857e788b76c042bfa34e Mon Sep 17 00:00:00 2001
From: Armin <armin@cherry>
Date: Mon, 6 Jul 2026 18:10:05 +0200
Subject: [PATCH] Add cutoff max falloff decay selector
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Introduce a new dropdown to control how fast the max-cutoff marker
decays toward the live cutoff on the realtime spectrum. Options:
  Off   — max cutoff holds indefinitely (manual reset only)
  Slow  — 1% gap reduction per frame
  Medium — 3% gap reduction per frame
  Fast   — 8% gap reduction per frame

Previously the max-cutoff line only went up and never came back down
unless the user clicked Reset.
---
 index.html | 6 ++++++
 js/app.js  | 7 +++++++
 2 files changed, 13 insertions(+)

diff --git a/index.html b/index.html
index 17f4aea..2929eed 100644
--- a/index.html
+++ b/index.html
@@ -38,6 +38,12 @@
           <option value="medium" selected>Hold: Medium</option>
           <option value="fast">Hold: Fast</option>
         </select>
+        <select id="cutoffFalloff" class="window-select" title="Cutoff max falloff decay">
+          <option value="off" selected>Cutoff: Off</option>
+          <option value="slow">Cutoff: Slow</option>
+          <option value="medium">Cutoff: Medium</option>
+          <option value="fast">Cutoff: Fast</option>
+        </select>
       </div>
       <div class="chart-container" style="position:relative">
         <canvas id="waveformChart"></canvas>
diff --git a/js/app.js b/js/app.js
index 2960e9f..1ee761b 100644
--- a/js/app.js
+++ b/js/app.js
@@ -668,6 +668,13 @@ const App = {
     const nyquist = sr / 2;
     const cutoffHz = (cutoffBin / len) * nyquist;
     if (cutoffHz > this.cutoffMaxHz) this.cutoffMaxHz = cutoffHz;
+    const falloffSel = document.getElementById('cutoffFalloff');
+    if (falloffSel && falloffSel.value !== 'off' && this.isPlaying && cutoffHz < this.cutoffMaxHz) {
+      const falloffMap = { slow: 0.01, medium: 0.03, fast: 0.08 };
+      const rate = falloffMap[falloffSel.value] ?? 0;
+      const gap = this.cutoffMaxHz - cutoffHz;
+      if (gap > 1) this.cutoffMaxHz -= gap * rate;
+    }
 
     const displayHz = this.cutoffHold && this.cutoffMaxHz > 0 ? this.cutoffMaxHz : cutoffHz;
     const displayBin = Math.round((displayHz / nyquist) * len);