Makes video filters automatically combine to allow de-interlacing when filters are executed

src/main/java/net/knarcraft/ffmpegconverter/container/FFMpegCommand.java

@@ -18,6 +18,7 @@ public class FFMpegCommand implements Cloneable {
     private @NotNull List<String> outputFileOptions;
     private @Nullable String outputVideoCodec;
     private @NotNull String outputFile;
+    private @NotNull String videoFilter = "";
 
     /**
      * Instantiates a new FFMPEG command
@@ -83,6 +84,21 @@ public class FFMpegCommand implements Cloneable {
      * @param argument <p>The output file option(s) to add</p>
      */
     public void addOutputFileOption(@NotNull String... argument) {
+        StringBuilder filterBuilder = new StringBuilder(this.videoFilter);
+        for (int i = 0; i < argument.length; i++) {
+            if (argument[i].equals("-vf") || argument[i].equals("-filter:v")) {
+                if (!filterBuilder.toString().isBlank()) {
+                    filterBuilder.append(", ").append(argument[i + 1]);
+                } else {
+                    filterBuilder.append(argument[i + 1]);
+                }
+            }
+        }
+        if (!this.videoFilter.contentEquals(filterBuilder)) {
+            this.videoFilter = filterBuilder.toString();
+            return;
+        }
+
         this.outputFileOptions.addAll(List.of(argument));
 
         // Detect when the output video codec is set
@@ -129,6 +145,10 @@ public class FFMpegCommand implements Cloneable {
             result.add(inputFile);
         }
         result.addAll(outputFileOptions);
+        if (!videoFilter.isBlank()) {
+            result.add("-vf");
+            result.add("\"" + videoFilter + "\"");
+        }
         if (!outputFile.isEmpty()) {
             result.add(outputFile);
         }

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

@@ -151,7 +151,7 @@ public class LetterboxCropper extends AbstractConverter {
         probeCommand.addOutputFileOption("-vframes", "10");
         probeCommand.addOutputFileOption("-vf", "cropdetect");
         probeCommand.addOutputFileOption("-f", "null");
-        probeCommand.addOutputFileOption("-");
+        probeCommand.setOutputFile("-");
 
         double duration;
         try {