diff --git a/src/java/com/threerings/openal/FileStream.java b/src/java/com/threerings/openal/FileStream.java
index 9ef73813..c8c355f7 100644
--- a/src/java/com/threerings/openal/FileStream.java
+++ b/src/java/com/threerings/openal/FileStream.java
@@ -21,32 +21,18 @@
 
 package com.threerings.openal;
 
-import java.util.HashMap;
-
 import java.io.File;
-import java.io.FileInputStream;
 import java.io.IOException;
-import java.io.InputStream;
 
 import java.nio.ByteBuffer;
 
 import java.util.ArrayList;
 
-import org.lwjgl.openal.AL10;
-
 /**
  * An audio stream read from one or more files.
  */
 public class FileStream extends Stream
 {
-    /**
-     * Registers a class of {@link StreamDecoder} for the specified file extension.
-     */
-    public static void registerExtension (String extension, Class clazz)
-    {
-        _extensions.put(extension, clazz);
-    }
-
     /**
      * Creates a new stream for the specified file.
      *
@@ -58,7 +44,7 @@ public class FileStream extends Stream
     {
         super(soundmgr);
         _file = new QueuedFile(file, loop);
-        _decoder = createDecoder(file);
+        _decoder = StreamDecoder.createInstance(file);
     }
 
     /**
@@ -93,43 +79,13 @@ public class FileStream extends Stream
             if (!_queue.isEmpty()) {
                 _file = _queue.remove(0);
             }
-            _decoder = createDecoder(_file.file);
+            _decoder = StreamDecoder.createInstance(_file.file);
             read = Math.max(0, read);
             read += _decoder.read(buf);
         }
         return read;
     }
 
-    /**
-     * Creates and initializes a stream decoder for the specified file.
-     */
-    protected StreamDecoder createDecoder (File file)
-        throws IOException
-    {
-        String path = file.getPath();
-        int idx = path.lastIndexOf('.');
-        if (idx == -1) {
-            Log.warning("Missing extension for file [file=" + path + "].");
-            return null;
-        }
-        String extension = path.substring(idx+1);
-        Class clazz = _extensions.get(extension);
-        if (clazz == null) {
-            Log.warning("No decoder registered for extension [extension=" + extension +
-                ", file=" + path + "].");
-            return null;
-        }
-        StreamDecoder decoder;
-        try {
-            decoder = (StreamDecoder)clazz.newInstance();
-        } catch (Exception e) {
-            Log.warning("Error instantiating decoder [file=" + path + ", error=" + e + "].");
-            return null;
-        }
-        decoder.init(new FileInputStream(file));
-        return decoder;
-    }
-
     /** The file currently being played. */
     protected QueuedFile _file;
 
@@ -155,11 +111,4 @@ public class FileStream extends Stream
             this.loop = loop;
         }
     }
-
-    /** Registered decoder classes. */
-    protected static HashMap<String, Class> _extensions = new HashMap<String, Class>();
-    static {
-        registerExtension("ogg", OggStreamDecoder.class);
-        registerExtension("mp3", Mp3StreamDecoder.class);
-    }
 }
diff --git a/src/java/com/threerings/openal/Mp3StreamDecoder.java b/src/java/com/threerings/openal/Mp3StreamDecoder.java
index 225229c5..c0522458 100644
--- a/src/java/com/threerings/openal/Mp3StreamDecoder.java
+++ b/src/java/com/threerings/openal/Mp3StreamDecoder.java
@@ -37,8 +37,7 @@ import javazoom.jl.decoder.SampleBuffer;
 /**
  * Decodes MP3 streams.
  */
-public class Mp3StreamDecoder
-    implements StreamDecoder
+public class Mp3StreamDecoder extends StreamDecoder
 {
     // documentation inherited
     public void init (InputStream in)
diff --git a/src/java/com/threerings/openal/OggStreamDecoder.java b/src/java/com/threerings/openal/OggStreamDecoder.java
index 5cafa6d9..8c89be96 100644
--- a/src/java/com/threerings/openal/OggStreamDecoder.java
+++ b/src/java/com/threerings/openal/OggStreamDecoder.java
@@ -33,8 +33,7 @@ import com.jmex.sound.openAL.objects.util.OggInputStream;
 /**
  * Decodes Ogg Vorbis streams.
  */
-public class OggStreamDecoder
-    implements StreamDecoder
+public class OggStreamDecoder extends StreamDecoder
 {
     // documentation inherited
     public void init (InputStream in)
diff --git a/src/java/com/threerings/openal/StreamDecoder.java b/src/java/com/threerings/openal/StreamDecoder.java
index 858918ce..b7758af6 100644
--- a/src/java/com/threerings/openal/StreamDecoder.java
+++ b/src/java/com/threerings/openal/StreamDecoder.java
@@ -21,6 +21,10 @@
 
 package com.threerings.openal;
 
+import java.util.HashMap;
+
+import java.io.File;
+import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 
@@ -29,8 +33,46 @@ import java.nio.ByteBuffer;
 /**
  * Decodes audio streams from data read from an {@link InputStream}.
  */
-public interface StreamDecoder
+public abstract class StreamDecoder
 {
+    /**
+     * Registers a class of {@link StreamDecoder} for the specified file extension.
+     */
+    public static void registerExtension (String extension, Class clazz)
+    {
+        _extensions.put(extension, clazz);
+    }
+
+    /**
+     * Creates and initializes a stream decoder for the specified file.
+     */
+    public static StreamDecoder createInstance (File file)
+        throws IOException
+    {
+        String path = file.getPath();
+        int idx = path.lastIndexOf('.');
+        if (idx == -1) {
+            Log.warning("Missing extension for file [file=" + path + "].");
+            return null;
+        }
+        String extension = path.substring(idx+1);
+        Class clazz = _extensions.get(extension);
+        if (clazz == null) {
+            Log.warning("No decoder registered for extension [extension=" + extension +
+                ", file=" + path + "].");
+            return null;
+        }
+        StreamDecoder decoder;
+        try {
+            decoder = (StreamDecoder)clazz.newInstance();
+        } catch (Exception e) {
+            Log.warning("Error instantiating decoder [file=" + path + ", error=" + e + "].");
+            return null;
+        }
+        decoder.init(new FileInputStream(file));
+        return decoder;
+    }
+
     /**
      * Initializes the decoder with its input stream.
      */
@@ -55,4 +97,11 @@ public interface StreamDecoder
      */
     public abstract int read (ByteBuffer buf)
         throws IOException;
+
+    /** Maps file extensions to decoder classes. */
+    protected static HashMap<String, Class> _extensions = new HashMap<String, Class>();
+    static {
+        registerExtension("ogg", OggStreamDecoder.class);
+        registerExtension("mp3", Mp3StreamDecoder.class);
+    }
 }