From a5e10f4d2feb18b32777bfada16ec1545ae9c0c2 Mon Sep 17 00:00:00 2001
From: Marshall Lochbaum <mwlochbaum@gmail.com>
Date: Mon, 7 Dec 2020 22:04:04 -0500
Subject: Add some mixing functionality

---
 mix.bqn | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 mix.bqn

diff --git a/mix.bqn b/mix.bqn
new file mode 100644
index 0000000..1ad248f
--- /dev/null
+++ b/mix.bqn
@@ -0,0 +1,34 @@
+"mix.bqn takes a single option namespace, or no arguments" ! 1≥≠•args
+o ← ≠◶⟨•Import∘"options.bqn", ⊑⟩ •args
+
+# List of length |𝕩 that starts at 0 and stops just before 1,
+# reversed if 𝕩<0.
+I ⇐ <⟜0 ⌽∘⊢⍟⊣ ↕∘|⊸÷
+
+# Add two signals 𝕨 and 𝕩 or a list of signals 𝕩,
+# extending to the length of the longest signal.
+Add ⇐ +´ ·(⌈´(¯1⊑≢)¨)⊸(↑⎉1¨) ⊢⊘(≍○<)
+# Like add, but concatenate instead.
+Concat ⇐ (∾ ↓¨˜⟜(<0⥊˜·⌈´=¨)) ⊘ (∾⎉1)
+# Like ⌽⎉1, but the end of the signal does not wrap around.
+Shift ⇐ <⟜0◶⟨↓⎉1 , (-⥊0˙)⊸(∾⎉1)⟩
+# Repeat signal 𝕩 𝕨 times.
+Rep ⇐ (⥊/⟜≍)⎉1
+# 𝕨 is location‿length. Obtain that part of signal 𝕩.
+Slice ⇐ (SliceI ← +⟜(0⊸⌊+↕∘|)´) ⊏⎉1 ⊢
+# Apply 𝔽 to the slice of 𝕩 given by 𝕨.
+_onSlice ⇐ { 𝔽⌾((SliceI𝕨)⊏⎉1⊢) 𝕩 }
+
+# Convert possibly-mono signal to stereo
+Stereo ⇐ ≍˜⍟(2>=)
+# Pan signal 𝕩 to position 𝕨, where 0 is hard left and 1 is hard right
+Pan ⇐ (25⌊∘×≍⟜¬∘⊣) ⥊⟜0⊸»˘ ((=⌜˜↕2)-·(××⌜0⊸⌈)·≍⟜-1-˜2×⊣)⊸(+˝∘×⎉¯1‿∞)⟜Stereo
+
+# Multiply leading or trailing samples of 𝕩 by 𝕨.
+Fadefront‿Fadeback ⇐ {𝕊f: {𝕨⊸×⌾((F≠𝕨)↑⊢)𝕩}⎉1 }¨ ⊢‿-
+
+# 𝕗 is the overlap amount. Fade 𝕨 into 𝕩, linearly.
+_crossfade ⇐ {
+  G←↑≍○<↓
+  (-𝕗)⊸G⊸(∾ 1⌽∾˜○(1⊸↓) ∾⟜< (¬⊸≍I𝕗)+˝∘×≍○⊑)⟜(𝕗⊸G)⎉1
+}
-- 
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