From 198eb54ce24dd23eb5f98bb53fd4427505a542f3 Mon Sep 17 00:00:00 2001
From: "prompt.ac/@jeffrey" <mail@aesthetic.computer>
Date: Fri, 3 Jul 2026 15:37:50 -0700
Subject: [PATCH] menuband: fade-in the sample start to swallow the record-key
 click
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15ms cosine fade-in on the captured buffer. The key click sits at t=0, so
ramping up from silence attenuates the residual transient the front-skip/trim
misses, without touching the sample body — and makes the looped boundary
click-free too.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---
 .../Sources/MenuBand/MenuBandSampleVoice.swift       | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/slab/menuband/Sources/MenuBand/MenuBandSampleVoice.swift b/slab/menuband/Sources/MenuBand/MenuBandSampleVoice.swift
index 03727d376b..5c2a56dfcb 100644
--- a/slab/menuband/Sources/MenuBand/MenuBandSampleVoice.swift
+++ b/slab/menuband/Sources/MenuBand/MenuBandSampleVoice.swift
@@ -634,6 +634,18 @@ final class MenuBandSampleVoice {
             peakAfter = max(peakAfter, abs(s))
             sumSqAfter += s * s
         }
+        // Short cosine fade-in over the first ~15 ms. The record-key click sits
+        // right at the buffer start, so ramping up from silence smoothly
+        // swallows whatever transient survived the front-skip/trim, while the
+        // sample's body is untouched. Bonus: since the buffer loops, every loop
+        // now restarts from zero — no click at the loop boundary either.
+        let fadeFrames = min(frames, Int(sampleRate * 0.015))
+        if fadeFrames > 1 {
+            for i in 0..<fadeFrames {
+                let t = Float(i) / Float(fadeFrames)
+                data[i] *= 0.5 - 0.5 * cosf(Float.pi * t)   // 0 → 1
+            }
+        }
         let rmsAfter = sqrt(sumSqAfter / Float(frames))
         return (peakBefore, peakAfter, rmsBefore, rmsAfter, gain)
     }
-- 
2.51.2