diff --git a/api/system-current.txt b/api/system-current.txt
index 764709aad9462..6ae731c4325ba 100755
--- a/api/system-current.txt
+++ b/api/system-current.txt
@@ -5077,6 +5077,7 @@ package android.media.tv.tuner.filter {
     field public static final int TYPE_MMTP = 2; // 0x2
     field public static final int TYPE_TLV = 8; // 0x8
     field public static final int TYPE_TS = 1; // 0x1
+    field public static final int TYPE_UNDEFINED = 0; // 0x0
   }
 
   public interface FilterCallback {
diff --git a/media/java/android/media/tv/tuner/filter/Filter.java b/media/java/android/media/tv/tuner/filter/Filter.java
index cfb943b10d17b..52bdb595050ed 100644
--- a/media/java/android/media/tv/tuner/filter/Filter.java
+++ b/media/java/android/media/tv/tuner/filter/Filter.java
@@ -44,6 +44,10 @@ public class Filter implements AutoCloseable {
     @Retention(RetentionPolicy.SOURCE)
     public @interface Type {}
 
+    /**
+     * Undefined filter type.
+     */
+    public static final int TYPE_UNDEFINED = 0;
     /**
      * TS filter type.
      */
@@ -248,7 +252,6 @@ public class Filter implements AutoCloseable {
     /**
      * Gets the filter Id.
      */
-    @Result
     public int getId() {
         return nativeGetId();
     }
@@ -273,6 +276,8 @@ public class Filter implements AutoCloseable {
     /**
      * Starts filtering data.
      *
+     * <p>Does nothing if the filter is already started.
+     *
      * @return result status of the operation.
      */
     @Result
@@ -284,6 +289,8 @@ public class Filter implements AutoCloseable {
     /**
      * Stops filtering data.
      *
+     * <p>Does nothing if the filter is stopped or not started.
+     *
      * @return result status of the operation.
      */
     @Result
@@ -312,14 +319,13 @@ public class Filter implements AutoCloseable {
      * @param size the maximum number of bytes to read.
      * @return the number of bytes read.
      */
-    @Result
     public int read(@NonNull byte[] buffer, @BytesLong long offset, @BytesLong long size) {
         size = Math.min(size, buffer.length - offset);
         return nativeRead(buffer, offset, size);
     }
 
     /**
-     * Releases the Filter instance.
+     * Stops filtering data and releases the Filter instance.
      */
     @Override
     public void close() {