From 5f7a01e920865df43b4f61b3b73ed6d36314afcb Mon Sep 17 00:00:00 2001
From: Andrew Weaver <weevz@uw.edu>
Date: Wed, 14 Nov 2018 14:02:28 -0800
Subject: [PATCH] cd de-emph

---
 index.html | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/index.html b/index.html
index 7ee8e4c..7ed5a5e 100644
--- a/index.html
+++ b/index.html
@@ -883,6 +883,23 @@
     </div>
     <!-- ends RIAA equalization -->
 
+    <!-- CD De-emphasis -->
+    <label class="recipe" for="cd_eq">Reverse CD Pre-Emphasis</label>
+    <input type="checkbox" id="cd_eq">
+    <div class="hiding">
+      <h3>Reverse CD Pre-Emphasis</h3>
+      <p><code>ffmpeg -i <em>input_file</em> -af aemphasis=type=cd <em>output_file</em></code></p>
+      <p>This will apply de-emphasis to reverse the effects of CD pre-emphasis in the somewhat rare case of CDs that were created with this technology. Use this command to create more accurate listening copies of files that were ripped 'flat' (without any de-emphasis) where the original source utilized emphasis. For more information about CD pre-emphasis see the <a href="https://wiki.hydrogenaud.io/index.php?title=Pre-emphasis" target="_blank">Hydrogen Audio page</a> on this subject.</p>
+      <dl>
+        <dt>ffmpeg</dt><dd>starts the command</dd>
+        <dt><em>input_file</em></dt><dd>path, name and extension of the input file</dd>
+        <dt>-af aemphasis=type=cd</dt><dd>activates the aemphasis filter and sets it to use CD equalization</dd>
+        <dt><em>output_file</em></dt><dd>path and name of output file</dd>
+      </dl>
+      <p class="link"></p>
+    </div>
+    <!-- CD De-emphasis -->
+
     <!-- one pass loudnorm -->
     <label class="recipe" for="loudnorm_one_pass">One Pass Loudness Normalization</label>
     <input type="checkbox" id="loudnorm_one_pass">