Fixes subtitle mapping for video with only external subtitles

src/main/java/net/knarcraft/ffmpegconverter/converter/MkvH264Converter.java

@@ -56,7 +56,7 @@ public class MkvH264Converter extends AbstractConverter {
         }
 
         // Map subtitles if present
-        if (!filterStreamsByType(streams, SubtitleStream.class).isEmpty()) {
+        if (hasInternalStreams(streams)) {
             command.add("-map");
             command.add("0:s");
             command.add("-c:s");
@@ -72,4 +72,20 @@ public class MkvH264Converter extends AbstractConverter {
         return command.toArray(new String[0]);
     }
 
+    /**
+     * Checks whether the processed file has any internal subtitle streams
+     *
+     * @param streams <p>All parsed streams for the video file</p>
+     * @return <p>True if the file has at least one internal subtitle stream</p>
+     */
+    private boolean hasInternalStreams(List<StreamObject> streams) {
+        for (StreamObject subtitleStream : filterStreamsByType(streams, SubtitleStream.class)) {
+            if (((SubtitleStream) subtitleStream).isInternalSubtitle()) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
 }

src/main/java/net/knarcraft/ffmpegconverter/streams/SubtitleStream.java

@@ -9,6 +9,7 @@ public class SubtitleStream extends AbstractStream implements StreamObject {
     final private String file;
     final private boolean isFullSubtitle;
     final private boolean isImageSubtitle;
+    final private boolean isInternalStream;
 
     /**
      * Instantiates a new subtitle stream
@@ -19,9 +20,10 @@ public class SubtitleStream extends AbstractStream implements StreamObject {
      * @param language         <p>The language of the subtitle stream.</p>
      * @param title            <p>The title of the subtitle stream.</p>
      * @param file             <p>The file containing the subtitle.</p>
+     * @param isInternalStream <p>Whether this subtitle stream is in the video file itself</p>
      */
     public SubtitleStream(String codecName, int absoluteIndex, int relativeIndex, String language, String title,
-                          String file) {
+                          String file, boolean isInternalStream) {
         this.codecName = codecName;
         this.absoluteIndex = absoluteIndex;
         this.language = language;
@@ -29,6 +31,7 @@ public class SubtitleStream extends AbstractStream implements StreamObject {
         this.isFullSubtitle = isFullSubtitle();
         this.relativeIndex = relativeIndex;
         this.isImageSubtitle = isImageSubtitle();
+        this.isInternalStream = isInternalStream;
         this.file = file;
     }
 
@@ -50,6 +53,15 @@ public class SubtitleStream extends AbstractStream implements StreamObject {
         return this.file;
     }
 
+    /**
+     * Gets whether this subtitle stream is an internal stream, not an external one
+     *
+     * @return <p>True if this stream is an internal stream</p>
+     */
+    public boolean isInternalSubtitle() {
+        return this.isInternalStream;
+    }
+
     /**
      * Gets whether the subtitle is an image subtitle
      *

src/main/java/net/knarcraft/ffmpegconverter/utility/FFMpegHelper.java

@@ -285,7 +285,7 @@ public final class FFMpegHelper {
             } else if (stream.contains("codec_type=audio")) {
                 parsedStreams.add(parseAudioStream(streamParts, relativeAudioIndex++));
             } else if (stream.contains("codec_type=subtitle")) {
-                parsedStreams.add(parseSubtitleStream(streamParts, relativeSubtitleIndex++, file.getName()));
+                parsedStreams.add(parseSubtitleStream(streamParts, relativeSubtitleIndex++, file.getName(), true));
             }
         }
         List<StreamObject> externalSubtitles = getExternalSubtitles(ffprobePath, file.getParentFile(), file.getName());
@@ -323,7 +323,7 @@ public final class FFMpegHelper {
             String[] streams = probeForStreams(ffprobePath, subtitleFile);
             for (String stream : streams) {
                 String[] streamParts = stream.split(PROBE_SPLIT_CHARACTER);
-                parsedStreams.add(parseSubtitleStream(streamParts, 0, subtitleFile.getName()));
+                parsedStreams.add(parseSubtitleStream(streamParts, 0, subtitleFile.getName(), false));
             }
         }
         return parsedStreams;
@@ -408,11 +408,12 @@ public final class FFMpegHelper {
      * @param streamParts      <p>A list of parameters belonging to a subtitle stream.</p>
      * @param relativeIndex    <p>The relative index of the subtitle.</p>
      * @param file             <p>The file currently being converted.</p>
+     * @param isInternalStream <p>Whether the subtitle stream is in the main video file</p>
      * @return <p>A SubtitleStream object.</p>
      * @throws NumberFormatException <p>If codec index contains a non-numeric value.</p>
      */
-    private static SubtitleStream parseSubtitleStream(String[] streamParts, int relativeIndex, String file)
+    private static SubtitleStream parseSubtitleStream(String[] streamParts, int relativeIndex, String file,
-            throws NumberFormatException {
+                                                      boolean isInternalStream) throws NumberFormatException {
         String codecName = null;
         int absoluteIndex = -1;
         String language = null;
@@ -428,7 +429,7 @@ public final class FFMpegHelper {
                 title = streamPart.replace("TAG:title=", "");
             }
         }
-        return new SubtitleStream(codecName, absoluteIndex, relativeIndex, language, title, file);
+        return new SubtitleStream(codecName, absoluteIndex, relativeIndex, language, title, file, isInternalStream);
     }
 
 }