Also extract subtitles of MKS aux files if they're extractable.

MediaBrowser.MediaEncoding/Subtitles/SubtitleEncoder.cs

@@ -489,10 +489,15 @@ namespace MediaBrowser.MediaEncoding.Subtitles
             try
             {
                 var subtitleStreams = mediaSource.MediaStreams
-                    .Where(stream => stream is { IsExtractableSubtitleStream: true, SupportsExternalStream: true, IsExternal: false });
+                    .Where(stream => stream is { IsExtractableSubtitleStream: true, SupportsExternalStream: true });
 
                 foreach (var subtitleStream in subtitleStreams)
                 {
+                    if (subtitleStream.IsExternal && !subtitleStream.Path.EndsWith(".mks", StringComparison.OrdinalIgnoreCase))
+                    {
+                        continue;
+                    }
+
                     var outputPath = GetSubtitleCachePath(mediaSource, subtitleStream.Index, "." + GetExtractableSubtitleFileExtension(subtitleStream));
 
                     var releaser = await _semaphoreLocks.LockAsync(outputPath, cancellationToken).ConfigureAwait(false);
@@ -510,6 +515,7 @@ namespace MediaBrowser.MediaEncoding.Subtitles
                 if (extractableStreams.Count > 0)
                 {
                     await ExtractAllExtractableSubtitlesInternal(mediaSource, extractableStreams, cancellationToken).ConfigureAwait(false);
+                    await ExtractAllExtractableSubtitlesMKS(mediaSource, extractableStreams, cancellationToken).ConfigureAwait(false);
                 }
             }
             catch (Exception ex)
@@ -522,6 +528,72 @@ namespace MediaBrowser.MediaEncoding.Subtitles
             }
         }
 
+        private async Task ExtractAllExtractableSubtitlesMKS(
+           MediaSourceInfo mediaSource,
+           List<MediaStream> subtitleStreams,
+           CancellationToken cancellationToken)
+        {
+            var mksFiles = new List<string>();
+
+            foreach (var subtitleStream in subtitleStreams)
+            {
+                if (!subtitleStream.Path.EndsWith(".mks", StringComparison.OrdinalIgnoreCase))
+                {
+                    continue;
+                }
+
+                if (!mksFiles.Contains(subtitleStream.Path))
+                {
+                    mksFiles.Add(subtitleStream.Path);
+                }
+            }
+
+            if (mksFiles.Count == 0)
+            {
+                return;
+            }
+
+            foreach (string mksFile in mksFiles)
+            {
+                var inputPath = _mediaEncoder.GetInputArgument(mksFile, mediaSource);
+                var outputPaths = new List<string>();
+                var args = string.Format(
+                CultureInfo.InvariantCulture,
+                "-i {0} -copyts",
+                inputPath);
+
+                foreach (var subtitleStream in subtitleStreams)
+                {
+                    if (!subtitleStream.Path.Equals(mksFile, StringComparison.OrdinalIgnoreCase))
+                    {
+                        continue;
+                    }
+
+                    var outputPath = GetSubtitleCachePath(mediaSource, subtitleStream.Index, "." + GetExtractableSubtitleFileExtension(subtitleStream));
+                    var outputCodec = IsCodecCopyable(subtitleStream.Codec) ? "copy" : "srt";
+                    var streamIndex = EncodingHelper.FindIndex(mediaSource.MediaStreams, subtitleStream);
+
+                    if (streamIndex == -1)
+                    {
+                        _logger.LogError("Cannot find subtitle stream index for {InputPath} ({Index}), skipping this stream", inputPath, subtitleStream.Index);
+                        continue;
+                    }
+
+                    Directory.CreateDirectory(Path.GetDirectoryName(outputPath) ?? throw new FileNotFoundException($"Calculated path ({outputPath}) is not valid."));
+
+                    outputPaths.Add(outputPath);
+                    args += string.Format(
+                        CultureInfo.InvariantCulture,
+                        " -map 0:{0} -an -vn -c:s {1} \"{2}\"",
+                        streamIndex,
+                        outputCodec,
+                        outputPath);
+                }
+
+                await ExtractSubtitlesForFile(inputPath, args, outputPaths, cancellationToken).ConfigureAwait(false);
+            }
+        }
+
         private async Task ExtractAllExtractableSubtitlesInternal(
             MediaSourceInfo mediaSource,
             List<MediaStream> subtitleStreams,
@@ -540,7 +612,7 @@ namespace MediaBrowser.MediaEncoding.Subtitles
                 var outputCodec = IsCodecCopyable(subtitleStream.Codec) ? "copy" : "srt";
                 var streamIndex = EncodingHelper.FindIndex(mediaSource.MediaStreams, subtitleStream);
 
-                if (streamIndex == -1)
+                if (streamIndex == -1 || subtitleStream.Path.EndsWith(".mks", StringComparison.OrdinalIgnoreCase))
                 {
                     _logger.LogError("Cannot find subtitle stream index for {InputPath} ({Index}), skipping this stream", inputPath, subtitleStream.Index);
                     continue;
@@ -557,6 +629,15 @@ namespace MediaBrowser.MediaEncoding.Subtitles
                     outputPath);
             }
 
+            await ExtractSubtitlesForFile(inputPath, args, outputPaths, cancellationToken).ConfigureAwait(false);
+        }
+
+        private async Task ExtractSubtitlesForFile(
+            string inputPath,
+            string args,
+            List<string> outputPaths,
+            CancellationToken cancellationToken)
+        {
             int exitCode;
 
             using (var process = new Process