From e7a980d55ab157e1ed52345c1989a41c9bd815f9 Mon Sep 17 00:00:00 2001
From: Quentin King <youremail@example.com>
Date: Sun, 4 Jan 2026 09:43:59 -0600
Subject: [PATCH] Adds extended metadata fields to FFmpeg output

Enriches audiobook metadata by adding support for additional fields including abridged/unabridged format, full publication date, ISBN, language, explicit content flags, and subtitle.

Improves compatibility with Libation by including both lowercase and uppercase ASIN variants.

Sets appropriate iTunes advisory flags to distinguish explicit from clean content.
---
 server/utils/ffmpegHelpers.js | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/server/utils/ffmpegHelpers.js b/server/utils/ffmpegHelpers.js
index ecc86f454..ef0447347 100644
--- a/server/utils/ffmpegHelpers.js
+++ b/server/utils/ffmpegHelpers.js
@@ -400,14 +400,24 @@ function escapeFFMetadataValue(value) {
  * @returns {Object} - The FFmpeg metadata object.
  */
 function getFFMetadataObject(libraryItem, audioFilesLength) {
+  // Determine abridged/unabridged format string
+  let format = null
+  if (libraryItem.media.abridged === true) {
+    format = 'abridged'
+  } else if (libraryItem.media.abridged === false) {
+    format = 'unabridged'
+  }
+
   const ffmetadata = {
     title: libraryItem.media.title,
     artist: libraryItem.media.authorName,
     album_artist: libraryItem.media.authorName,
     album: (libraryItem.media.title || '') + (libraryItem.media.subtitle ? `: ${libraryItem.media.subtitle}` : ''),
     TIT3: libraryItem.media.subtitle, // mp3 only
+    subtitle: libraryItem.media.subtitle, // m4b/mp4
     genre: libraryItem.media.genres?.join('; '),
     date: libraryItem.media.publishedYear,
+    RELEASETIME: libraryItem.media.publishedDate, // Full release date YYYY-MM-DD
     comment: libraryItem.media.description,
     description: libraryItem.media.description,
     composer: (libraryItem.media.narrators || []).join(', '),
@@ -415,7 +425,13 @@ function getFFMetadataObject(libraryItem, audioFilesLength) {
     publisher: libraryItem.media.publisher, // mp3 only
     TRACKTOTAL: `${audioFilesLength}`, // mp3 only
     grouping: libraryItem.media.series?.map((s) => s.name + (s.bookSeries.sequence ? ` #${s.bookSeries.sequence}` : '')).join('; '),
-    AUDIBLE_ASIN: libraryItem.media.asin // Audible ASIN tag for m4b/mp4 files
+    asin: libraryItem.media.asin, // Lowercase for Libation compatibility
+    AUDIBLE_ASIN: libraryItem.media.asin, // Uppercase for Libation compatibility
+    ISBN: libraryItem.media.isbn,
+    LANGUAGE: libraryItem.media.language,
+    EXPLICIT: libraryItem.media.explicit ? '1' : null,
+    ITUNESADVISORY: libraryItem.media.explicit ? '1' : '2', // 1 = explicit, 2 = clean
+    FORMAT: format
   }
   Object.keys(ffmetadata).forEach((key) => {
     if (!ffmetadata[key]) {