fixes #843 - Update Dlna to respect user audio/subtitle language settings

1 files changed, 103 insertions, 0 deletions

diff --git a/MediaBrowser.Controller/MediaEncoding/MediaStreamSelector.cs b/MediaBrowser.Controller/MediaEncoding/MediaStreamSelector.cs
new file mode 100644
index 000000000..58a68c257
--- /dev/null
+++ b/MediaBrowser.Controller/MediaEncoding/MediaStreamSelector.cs
@@ -0,0 +1,103 @@
+using MediaBrowser.Model.Configuration;
+using MediaBrowser.Model.Entities;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace MediaBrowser.Controller.MediaEncoding
+{
+    public static class MediaStreamSelector
+    {
+        public static int? GetDefaultAudioStreamIndex(List<MediaStream> streams, IEnumerable<string> preferredLanguages, bool preferDefaultTrack)
+        {
+            streams = GetSortedStreams(streams, MediaStreamType.Audio, preferredLanguages.ToList())
+               .ToList();
+
+            if (preferDefaultTrack)
+            {
+                var defaultStream = streams.FirstOrDefault(i => i.IsDefault);
+
+                if (defaultStream != null)
+                {
+                    return defaultStream.Index;
+                }
+            }
+
+            var stream = streams.FirstOrDefault();
+
+            if (stream != null)
+            {
+                return stream.Index;
+            }
+
+            return null;
+        }
+
+        public static int? GetDefaultSubtitleStreamIndex(List<MediaStream> streams,
+            IEnumerable<string> preferredLanguages,
+            SubtitlePlaybackMode mode,
+            string audioTrackLanguage)
+        {
+            var languages = preferredLanguages.ToList();
+            streams = GetSortedStreams(streams, MediaStreamType.Subtitle, languages).ToList();
+
+            var full = streams.Where(s => !s.IsForced);
+            var forced = streams.Where(s => s.IsForced && string.Equals(s.Language, audioTrackLanguage, StringComparison.OrdinalIgnoreCase));
+
+            MediaStream stream = null;
+
+            if (mode == SubtitlePlaybackMode.None)
+            {
+                return null;
+            }
+
+            if (mode == SubtitlePlaybackMode.Default)
+            {
+                // if the audio language is not understood by the user, load their preferred subs, if there are any
+                if (!ContainsOrdinal(languages, audioTrackLanguage))
+                {
+                    stream = full.FirstOrDefault(s => ContainsOrdinal(languages, s.Language));
+                }
+            }
+            else if (mode == SubtitlePlaybackMode.Always)
+            {
+                // always load the most suitable full subtitles
+                stream = full.FirstOrDefault();
+            }
+
+            // load forced subs if we have found no suitable full subtitles
+            stream = stream ?? forced.FirstOrDefault();
+
+            if (stream != null)
+            {
+                return stream.Index;
+            }
+
+            return null;
+        }
+
+        private static bool ContainsOrdinal(IEnumerable<string> list, string item)
+        {
+            return list.Any(i => string.Equals(i, item, StringComparison.OrdinalIgnoreCase));
+        }
+
+        private static IEnumerable<MediaStream> GetSortedStreams(IEnumerable<MediaStream> streams, MediaStreamType type, List<string> languagePreferences)
+        {
+            var orderStreams = streams
+                .Where(i => i.Type == type);
+
+            // Give some preferance to external text subs for better performance
+            return orderStreams.OrderBy(i =>
+            {
+                var index = languagePreferences.FindIndex(l => string.Equals(i.Language, l, StringComparison.OrdinalIgnoreCase));
+
+                return index == -1 ? 100 : index;
+            })
+                 .ThenBy(i => i.IsDefault)
+                 .ThenBy(i => i.IsTextSubtitleStream)
+                 .ThenBy(i => i.IsExternal)
+                 .ThenBy(i => i.Index)
+                 .ToList();
+        }
+    }
+}