add EBU loudness/peak value tags

Implements #831

Author: robUx4

cellar-tags/rfc_backmatter_tags.md

@@ -10,6 +10,22 @@
   </front>
 </reference>
 
+<reference anchor="EBU-R.128" target="https://tech.ebu.ch/publications/r128/">
+  <front>
+    <title>LOUDNESS NORMALISATION AND PERMITTED MAXIMUM LEVEL OF AUDIO SIGNALS</title>
+    <author/>
+     <date month="November" year="2023" />
+  </front>
+</reference>
+
+<reference anchor="EBU-TECH.3342" target="https://tech.ebu.ch/publications/tech3342">
+  <front>
+    <title>LOUDNESS RANGE: A MEASURE TO SUPPLEMENT EBU R 128 LOUDNESS NORMALIZATION</title>
+    <author/>
+     <date month="November" year="2023" />
+  </front>
+</reference>
+
 <reference anchor="GS1" target="https://www.gs1.org/standards/barcodes-epcrfid-id-keys/gs1-general-specifications">
   <front>
     <title>GS1 General Specifications</title>
@@ -29,6 +45,16 @@
   </front>
 </reference>
 
+<reference anchor="IEEE.754" target="https://standards.ieee.org/standard/754-2019.html">
+  <front>
+    <title>IEEE Standard for Binary Floating-Point Arithmetic</title>
+    <author>
+      <organization>IEEE</organization>
+    </author>
+    <date year="2019" month="June" day="13"/>
+  </front>
+</reference>
+
 <reference anchor="ID3v2.4" target="https://id3.org/id3v2.4.0-frames">
   <front>
     <title>ID3 tag version 2.4.0 - Native Frames</title>
@@ -89,6 +115,18 @@
   <seriesInfo name="IFPI" value="4th Edition" />
 </reference>
 
+<reference anchor="ITU-BS.1770" target="https://www.itu.int/rec/R-REC-BS.1770/en">
+  <front>
+    <title>Algorithms to measure audio programme loudness and true-peak audio level</title>
+    <author>
+      <organization>ITU-T</organization>
+    </author>
+    <date month="November" year="2023"/>
+  </front>
+  <seriesInfo name="ITU-T Recommendation" value="BS.1770" />
+</reference>
+
+
 <reference anchor="LCCN" target="https://www.loc.gov/marc/lccn.html">
   <front>
     <title>Library Of Congress Control Number</title>

matroska_tags.xml

@@ -340,6 +340,20 @@ the same tone as the musical piece (e.g., "441.34" in Hertz). The values is stor
       The value is a normalized absolute sample value of the target audio, using the Float number defined in (#number-tags-formatting) (e.g., "1.0129").
       Note that ReplayGain information can be found at all `TargetType` levels (track, album, etc).</description>
     </tag>
+    <tag name="EBU_R128_LOUDNESS" class="Technical Information" type="binary">
+      <description lang="en">EBU R 128 Loudness.
+      The value is the Loudness, K-weighted, relative to nominal full scale (LKFS) defined in [@!ITU-BS.1770] normalized to a Target Level of -23.0 LUFS as in [@!EBU-R.128].
+      This value is stored as a 32-bit floating-point number as defined in [@!IEEE.754] in little-endian order.</description>
+    </tag>
+    <tag name="EBU_R128_TRUE_PEAK" class="Technical Information" type="binary">
+      <description lang="en">EBU R 128 True-peak level.
+      This corresponds to the "true-peak level", in units of dB True Peak (dbTP), defined in [@!EBU-R.128].
+      This value is stored as a 32-bit floating-point number as defined in [@!IEEE.754] in little-endian order.</description>
+    </tag>
+    <tag name="EBU_3342_LOUDNESS_RANGE" class="Technical Information" type="binary">
+      <description lang="en">Loudness Range, measures the variation of loudness on a macroscopic time-scale, in units of LU (Loudness Units) as defined in [@!EBU-TECH.3342].
+      This value is stored as a 32-bit floating-point number as defined in [@!IEEE.754] in little-endian order.</description>
+    </tag>
 
     <tag name="ISRC" class="External Identifiers" type="UTF-8">
       <description lang="en">The International Standard Recording Code [@!ISRC],