only fetch language codes for the requested library when generating filter values

Emby.Server.Implementations/Library/LibraryManager.cs

@@ -3862,5 +3862,17 @@ namespace Emby.Server.Implementations.Library
         {
             return _mediaStreamRepository.GetMediaStreamLanguages(mediaStreamType);
         }
+
+        /// <inheritdoc />
+        public IReadOnlyList<string> GetMediaStreamLanguages(MediaStreamType mediaStreamType, InternalItemsQuery query)
+        {
+            if (query.User is not null)
+            {
+                AddUserToQuery(query, query.User);
+            }
+
+            SetTopParentOrAncestorIds(query);
+            return _itemRepository.GetMediaStreamLanguages(query, mediaStreamType);
+        }
     }
 }

Jellyfin.Api/Controllers/FilterController.cs

@@ -158,13 +158,42 @@ public class FilterController : BaseJellyfinApiController
             IsSeries = isSeries
         };
 
+        var streamLanguageQuery = new InternalItemsQuery(user)
+        {
+            // It's possible that different langauges are only available on alternative versions.
+            // To fetch them all, owned items are inlcluded.
+            IncludeOwnedItems = true,
+            IncludeItemTypes = includeItemTypes,
+            DtoOptions = new DtoOptions
+            {
+                Fields = Array.Empty<ItemFields>(),
+                EnableImages = false,
+                EnableUserData = false
+            },
+            IsAiring = isAiring,
+            IsMovie = isMovie,
+            IsSports = isSports,
+            IsKids = isKids,
+            IsNews = isNews,
+            IsSeries = isSeries
+        };
+
         if ((recursive ?? true) || parentItem is UserView || parentItem is ICollectionFolder)
         {
             genreQuery.AncestorIds = parentItem is null ? Array.Empty<Guid>() : new[] { parentItem.Id };
+            streamLanguageQuery.AncestorIds = parentItem is null ? Array.Empty<Guid>() : new[] { parentItem.Id };
         }
         else
         {
             genreQuery.Parent = parentItem;
+            streamLanguageQuery.Parent = parentItem;
+        }
+
+        if ((includeItemTypes.Contains(BaseItemKind.Series) || includeItemTypes.Contains(BaseItemKind.Season))
+            && !includeItemTypes.Contains(BaseItemKind.Episode))
+        {
+            // streams are joined on epsiodes not shows or seasons
+            streamLanguageQuery.IncludeItemTypes = [..includeItemTypes, BaseItemKind.Episode];
         }
 
         if (includeItemTypes.Length == 1
@@ -188,10 +217,13 @@ public class FilterController : BaseJellyfinApiController
             }).ToArray();
         }
 
-        if (includeItemTypes.Contains(BaseItemKind.Movie) || includeItemTypes.Contains(BaseItemKind.Series))
+        if (includeItemTypes.Contains(BaseItemKind.Movie)
+            || includeItemTypes.Contains(BaseItemKind.Series)
+            || includeItemTypes.Contains(BaseItemKind.Season)
+            || includeItemTypes.Contains(BaseItemKind.Episode))
         {
             filters.AudioLanguages = _libraryManager
-                .GetMediaStreamLanguages(MediaStreamType.Audio)
+                .GetMediaStreamLanguages(MediaStreamType.Audio, streamLanguageQuery)
                 .Select(language =>
                 {
                     var culture = _localization.FindLanguageInfo(language);
@@ -204,7 +236,7 @@ public class FilterController : BaseJellyfinApiController
                 .OrderBy(l => l.Name)
                 .ToArray();
             filters.SubtitleLanguages = _libraryManager
-                .GetMediaStreamLanguages(MediaStreamType.Subtitle)
+                .GetMediaStreamLanguages(MediaStreamType.Subtitle, streamLanguageQuery)
                 .Select(language =>
                 {
                     var culture = _localization.FindLanguageInfo(language);

Jellyfin.Server.Implementations/Item/BaseItemRepository.ByName.cs

@@ -7,6 +7,7 @@ using Jellyfin.Data.Enums;
 using Jellyfin.Database.Implementations.Entities;
 using MediaBrowser.Controller.Entities;
 using MediaBrowser.Model.Dto;
+using MediaBrowser.Model.Entities;
 using MediaBrowser.Model.Querying;
 using Microsoft.EntityFrameworkCore;
 using BaseItemDto = MediaBrowser.Controller.Entities.BaseItem;
@@ -81,6 +82,46 @@ public sealed partial class BaseItemRepository
             _itemTypeLookup.MusicGenreTypes);
     }
 
+    /// <inheritdoc />
+    public IReadOnlyList<string> GetMediaStreamLanguages(InternalItemsQuery filter, MediaStreamType mediaStreamType)
+    {
+        ArgumentNullException.ThrowIfNull(filter);
+
+        if (!filter.Limit.HasValue)
+        {
+            filter.EnableTotalRecordCount = false;
+        }
+
+        using var context = _dbProvider.CreateDbContext();
+
+        return TranslateQuery(
+            context.BaseItems.Include(e => e.MediaStreams).Where(e => e.Id != EF.Constant(PlaceholderId)),
+            context,
+            new InternalItemsQuery(filter.User)
+            {
+                IncludeOwnedItems = filter.IncludeOwnedItems,
+                ExcludeItemTypes = filter.ExcludeItemTypes,
+                IncludeItemTypes = filter.IncludeItemTypes,
+                MediaTypes = filter.MediaTypes,
+                AncestorIds = filter.AncestorIds,
+                ItemIds = filter.ItemIds,
+                TopParentIds = filter.TopParentIds,
+                ParentId = filter.ParentId,
+                IsAiring = filter.IsAiring,
+                IsMovie = filter.IsMovie,
+                IsSports = filter.IsSports,
+                IsKids = filter.IsKids,
+                IsNews = filter.IsNews,
+                IsSeries = filter.IsSeries
+            })
+            .Where(e => e.MediaStreams != null)
+            .SelectMany(e => e.MediaStreams!)
+            .Where(e => e.StreamType == (MediaStreamTypeEntity)mediaStreamType)
+            .Select(s => string.IsNullOrEmpty(s.Language) ? "und" : s.Language) // und = undetermined
+            .Distinct()
+            .ToArray();
+    }
+
     private string[] GetItemValueNames(IReadOnlyList<ItemValueType> itemValueTypes, IReadOnlyList<string> withItemTypes, IReadOnlyList<string> excludeItemTypes)
     {
         using var context = _dbProvider.CreateDbContext();

MediaBrowser.Controller/Library/ILibraryManager.cs

@@ -800,5 +800,13 @@ namespace MediaBrowser.Controller.Library
         /// <param name="mediaStreamType">The stream type.</param>
         /// <returns>List of language codes.</returns>
         IReadOnlyList<string> GetMediaStreamLanguages(MediaStreamType mediaStreamType);
+
+        /// <summary>
+        /// Gets a list of all language codes for the matching items and the the provided stream type.
+        /// </summary>
+        /// <param name="mediaStreamType">The stream type.</param>
+        /// <param name="query">The query filter.</param>
+        /// <returns>List of language codes.</returns>
+        IReadOnlyList<string> GetMediaStreamLanguages(MediaStreamType mediaStreamType, InternalItemsQuery query);
     }
 }

MediaBrowser.Controller/Persistence/IItemRepository.cs

@@ -7,6 +7,7 @@ using Jellyfin.Data.Enums;
 using Jellyfin.Database.Implementations.Entities;
 using MediaBrowser.Controller.Entities;
 using MediaBrowser.Model.Dto;
+using MediaBrowser.Model.Entities;
 using MediaBrowser.Model.Querying;
 
 namespace MediaBrowser.Controller.Persistence;
@@ -119,6 +120,14 @@ public interface IItemRepository
     /// <returns>The list of genre names.</returns>
     IReadOnlyList<string> GetGenreNames();
 
+    /// <summary>
+    /// Gets all language codes of the matching base items and the provided stream type.
+    /// </summary>
+    /// <param name="filter">The query filter.</param>
+    /// <param name="mediaStreamType">The type of the media stream.</param>
+    /// <returns>List of language codes.</returns>
+    public IReadOnlyList<string> GetMediaStreamLanguages(InternalItemsQuery filter, MediaStreamType mediaStreamType);
+
     /// <summary>
     /// Gets all artist names.
     /// </summary>