diff --git a/modules/mpv-player/android/src/main/java/expo/modules/mpvplayer/MPVLayerRenderer.kt b/modules/mpv-player/android/src/main/java/expo/modules/mpvplayer/MPVLayerRenderer.kt
index 6b41a621..3cd6732f 100644
--- a/modules/mpv-player/android/src/main/java/expo/modules/mpvplayer/MPVLayerRenderer.kt
+++ b/modules/mpv-player/android/src/main/java/expo/modules/mpvplayer/MPVLayerRenderer.kt
@@ -532,16 +532,27 @@ class MPVLayerRenderer(private val context: Context) : MPVLib.EventObserver {
             
             val trackId = mpv?.getPropertyInt("track-list/$i/id") ?: continue
             val track = mutableMapOf<String, Any>("id" to trackId)
-            
+
             mpv?.getPropertyString("track-list/$i/title")?.let { track["title"] = it }
             mpv?.getPropertyString("track-list/$i/lang")?.let { track["lang"] = it }
-            
+            mpv?.getPropertyString("track-list/$i/codec")?.let { track["codec"] = it }
+
+            // Identity fields used to map a Jellyfin subtitle to the real track
+            // (instead of fragile positional counting). `external` + `external-filename`
+            // uniquely identify a sub-added sidecar; `ff-index` aids embedded matching.
+            val external = mpv?.getPropertyBoolean("track-list/$i/external") ?: false
+            track["external"] = external
+            mpv?.getPropertyString("track-list/$i/external-filename")?.let {
+                track["externalFilename"] = it
+            }
+            mpv?.getPropertyInt("track-list/$i/ff-index")?.let { track["ffIndex"] = it }
+
             val selected = mpv?.getPropertyBoolean("track-list/$i/selected") ?: false
             track["selected"] = selected
-            
+
             tracks.add(track)
         }
-        
+
         return tracks
     }
     
diff --git a/modules/mpv-player/ios/MPVLayerRenderer.swift b/modules/mpv-player/ios/MPVLayerRenderer.swift
index 75bc3d9a..18b9ac4b 100644
--- a/modules/mpv-player/ios/MPVLayerRenderer.swift
+++ b/modules/mpv-player/ios/MPVLayerRenderer.swift
@@ -770,12 +770,32 @@ final class MPVLayerRenderer {
             if let lang = getStringProperty(handle: handle, name: "track-list/\(i)/lang") {
                 track["lang"] = lang
             }
-            
+
+            if let codec = getStringProperty(handle: handle, name: "track-list/\(i)/codec") {
+                track["codec"] = codec
+            }
+
+            // Identity fields used to map a Jellyfin subtitle to the real track
+            // (instead of fragile positional counting). `external` + `external-filename`
+            // uniquely identify a sub-added sidecar; `ff-index` aids embedded matching.
+            var external: Int32 = 0
+            getProperty(handle: handle, name: "track-list/\(i)/external", format: MPV_FORMAT_FLAG, value: &external)
+            track["external"] = external != 0
+
+            if let extFilename = getStringProperty(handle: handle, name: "track-list/\(i)/external-filename") {
+                track["externalFilename"] = extFilename
+            }
+
+            var ffIndex: Int64 = 0
+            if getProperty(handle: handle, name: "track-list/\(i)/ff-index", format: MPV_FORMAT_INT64, value: &ffIndex) >= 0 {
+                track["ffIndex"] = Int(ffIndex)
+            }
+
             var selected: Int32 = 0
             getProperty(handle: handle, name: "track-list/\(i)/selected", format: MPV_FORMAT_FLAG, value: &selected)
             track["selected"] = selected != 0
-            
-            Logger.shared.log("getSubtitleTracks: found sub track id=\(trackId), title=\(track["title"] ?? "none"), lang=\(track["lang"] ?? "none")", type: "Info")
+
+            Logger.shared.log("getSubtitleTracks: found sub track id=\(trackId), title=\(track["title"] ?? "none"), lang=\(track["lang"] ?? "none"), external=\(external != 0)", type: "Info")
             tracks.append(track)
         }
         
diff --git a/modules/mpv-player/src/MpvPlayer.types.ts b/modules/mpv-player/src/MpvPlayer.types.ts
index 17ee75de..ac3b7fba 100644
--- a/modules/mpv-player/src/MpvPlayer.types.ts
+++ b/modules/mpv-player/src/MpvPlayer.types.ts
@@ -141,6 +141,14 @@ export type SubtitleTrack = {
   id: number;
   title?: string;
   lang?: string;
+  /** Subtitle codec (mpv `codec`), e.g. "subrip", "ass", "hdmv_pgs_subtitle". */
+  codec?: string;
+  /** True if loaded from a separate file via `sub-add` (mpv `external`). */
+  external?: boolean;
+  /** For external tracks: the exact URL/path it was loaded from (mpv `external-filename`). */
+  externalFilename?: string;
+  /** FFmpeg stream index (mpv `ff-index`); not guaranteed for non-lavf demuxers. */
+  ffIndex?: number;
   selected?: boolean;
 };