diff --git a/src/main/java/net/knarcraft/ffmpegconverter/converter/AbstractConverter.java b/src/main/java/net/knarcraft/ffmpegconverter/converter/AbstractConverter.java
index cbc40cd..4c2a4f8 100644
--- a/src/main/java/net/knarcraft/ffmpegconverter/converter/AbstractConverter.java
+++ b/src/main/java/net/knarcraft/ffmpegconverter/converter/AbstractConverter.java
@@ -18,7 +18,7 @@ import java.util.List;
  */
 public abstract class AbstractConverter implements Converter {
     final boolean debug = false;
-    private final String newExtension;
+    private final String outputExtension;
     String ffprobePath;
     String ffmpegPath;
     String[] audioFormats;
@@ -27,8 +27,8 @@ public abstract class AbstractConverter implements Converter {
     /**
      * Initializes variables used by the abstract converter
      */
-    AbstractConverter(String newExtension) {
-        this.newExtension = newExtension;
+    AbstractConverter(String outputExtension) {
+        this.outputExtension = outputExtension;
         OutputUtil.setDebug(this.debug);
         try {
             audioFormats = FileUtil.readFileLines("audio_formats.txt");
@@ -127,7 +127,7 @@ public abstract class AbstractConverter implements Converter {
             throw new IllegalArgumentException("The file has no valid streams. Please make sure the file exists and" +
                     " is not corrupt.");
         }
-        String newPath = FileUtil.getNonCollidingPath(folder, file, newExtension);
+        String newPath = FileUtil.getNonCollidingPath(folder, file, outputExtension);
         OutputUtil.println();
         OutputUtil.println("Preparing to start process...");
         OutputUtil.println("Converting " + file);
@@ -138,11 +138,10 @@ public abstract class AbstractConverter implements Converter {
     /**
      * Gets the first audio stream from a list of streams
      *
-     * @param streams <p>A list of all streams.</p>
+     * @param audioStreams <p>A list of all streams.</p>
      * @return <p>The first audio stream found or null if no audio streams were found.</p>
      */
-    AudioStream getFirstAudioSteam(List<StreamObject> streams) {
-        List<AudioStream> audioStreams = filterStreamsByType(streams, AudioStream.class);
+    AudioStream getFirstAudioStream(List<AudioStream> audioStreams) {
         AudioStream audioStream = null;
         if (audioStreams.size() > 0) {
             audioStream = audioStreams.get(0);
@@ -153,11 +152,10 @@ public abstract class AbstractConverter implements Converter {
     /**
      * Gets the first subtitle stream from a list of streams
      *
-     * @param streams <p>A list of all streams.</p>
+     * @param subtitleStreams <p>A list of all subtitle streams.</p>
      * @return <p>The first subtitle stream found or null if no subtitle streams were found.</p>
      */
-    SubtitleStream getFirstSubtitleStream(List<StreamObject> streams) {
-        List<SubtitleStream> subtitleStreams = filterStreamsByType(streams, SubtitleStream.class);
+    SubtitleStream getFirstSubtitleStream(List<SubtitleStream> subtitleStreams) {
         SubtitleStream subtitleStream = null;
         if (subtitleStreams.size() > 0) {
             subtitleStream = subtitleStreams.get(0);
@@ -168,11 +166,10 @@ public abstract class AbstractConverter implements Converter {
     /**
      * Gets the first video stream from a list of streams
      *
-     * @param streams <p>A list of all streams.</p>
+     * @param videoStreams <p>A list of all streams.</p>
      * @return <p>The first video stream found or null if no video streams were found.</p>
      */
-    VideoStream getFirstVideoStream(List<StreamObject> streams) {
-        List<VideoStream> videoStreams = filterStreamsByType(streams, VideoStream.class);
+    VideoStream getFirstVideoStream(List<VideoStream> videoStreams) {
         VideoStream videoStream = null;
         if (videoStreams.size() > 0) {
             videoStream = videoStreams.get(0);
diff --git a/src/main/java/net/knarcraft/ffmpegconverter/converter/AdvancedConverter.java b/src/main/java/net/knarcraft/ffmpegconverter/converter/AdvancedConverter.java
index 519edff..64a6742 100644
--- a/src/main/java/net/knarcraft/ffmpegconverter/converter/AdvancedConverter.java
+++ b/src/main/java/net/knarcraft/ffmpegconverter/converter/AdvancedConverter.java
@@ -80,7 +80,7 @@ public class AdvancedConverter extends AbstractConverter {
 
             //Get the first audio stream in accordance with chosen languages
             List<AudioStream> audioStreams = filterAudioStreams(filterStreamsByType(streams, AudioStream.class), audioLanguages);
-            AudioStream audioStream = getFirstAudioSteam(new ArrayList<>(audioStreams));
+            AudioStream audioStream = getFirstAudioStream(new ArrayList<>(audioStreams));
 
             //Get the first subtitle stream in accordance with chosen languages and signs and songs prevention
             List<SubtitleStream> subtitleStreams = filterSubtitleStreams(filterStreamsByType(streams,
diff --git a/src/main/java/net/knarcraft/ffmpegconverter/converter/AnimeConverter.java b/src/main/java/net/knarcraft/ffmpegconverter/converter/AnimeConverter.java
index ff14aa9..9c114a1 100644
--- a/src/main/java/net/knarcraft/ffmpegconverter/converter/AnimeConverter.java
+++ b/src/main/java/net/knarcraft/ffmpegconverter/converter/AnimeConverter.java
@@ -49,7 +49,7 @@ public class AnimeConverter extends AbstractConverter {
 
         //Get the first audio stream in accordance with chosen languages
         List<AudioStream> audioStreams = filterAudioStreams(filterStreamsByType(streams, AudioStream.class), audioLanguages);
-        AudioStream audioStream = getFirstAudioSteam(new ArrayList<>(audioStreams));
+        AudioStream audioStream = getFirstAudioStream(new ArrayList<>(audioStreams));
 
         //Get the first subtitle stream in accordance with chosen languages and signs and songs prevention
         List<SubtitleStream> subtitleStreams = filterSubtitleStreams(filterStreamsByType(streams,
@@ -57,7 +57,7 @@ public class AnimeConverter extends AbstractConverter {
         SubtitleStream subtitleStream = getFirstSubtitleStream(new ArrayList<>(subtitleStreams));
 
         //Get the first video stream
-        VideoStream videoStream = getFirstVideoStream(streams);
+        VideoStream videoStream = getFirstVideoStream(filterStreamsByType(streams, VideoStream.class));
 
         //Add streams to output file
         FFMpegHelper.addAudioStream(command, audioStream, toStereo);
diff --git a/src/main/java/net/knarcraft/ffmpegconverter/converter/AudioConverter.java b/src/main/java/net/knarcraft/ffmpegconverter/converter/AudioConverter.java
index fa63110..b9536c7 100644
--- a/src/main/java/net/knarcraft/ffmpegconverter/converter/AudioConverter.java
+++ b/src/main/java/net/knarcraft/ffmpegconverter/converter/AudioConverter.java
@@ -33,7 +33,7 @@ public class AudioConverter extends AbstractConverter {
         }
 
         //Gets the first audio stream from the file and adds it to the output file
-        AudioStream audioStream = getFirstAudioSteam(streams);
+        AudioStream audioStream = getFirstAudioStream(filterStreamsByType(streams, AudioStream.class));
         FFMpegHelper.addAudioStream(command, audioStream, false);
         command.add(outFile);
 
diff --git a/src/main/java/net/knarcraft/ffmpegconverter/converter/WebVideoConverter.java b/src/main/java/net/knarcraft/ffmpegconverter/converter/WebVideoConverter.java
index 74363e9..6551350 100644
--- a/src/main/java/net/knarcraft/ffmpegconverter/converter/WebVideoConverter.java
+++ b/src/main/java/net/knarcraft/ffmpegconverter/converter/WebVideoConverter.java
@@ -37,9 +37,9 @@ public class WebVideoConverter extends AbstractConverter {
         }
 
         //Get first streams from the file
-        SubtitleStream subtitleStream = getFirstSubtitleStream(streams);
-        VideoStream videoStream = getFirstVideoStream(streams);
-        AudioStream audioStream = getFirstAudioSteam(streams);
+        SubtitleStream subtitleStream = getFirstSubtitleStream(filterStreamsByType(streams, SubtitleStream.class));
+        VideoStream videoStream = getFirstVideoStream(filterStreamsByType(streams, VideoStream.class));
+        AudioStream audioStream = getFirstAudioStream(filterStreamsByType(streams, AudioStream.class));
 
         //Add streams to output
         FFMpegHelper.addSubtitleAndVideoStream(command, subtitleStream, videoStream, file);