diff --git a/media/java/android/media/DataSourceCallback.java b/media/java/android/media/DataSourceCallback.java
index 0d4d53106c782..1afcd2075ba4d 100644
--- a/media/java/android/media/DataSourceCallback.java
+++ b/media/java/android/media/DataSourceCallback.java
@@ -47,7 +47,7 @@ public abstract class DataSourceCallback implements Closeable {
      * @param offset the offset within buffer to read the data into.
      * @param size the number of bytes to read.
      * @throws IOException on fatal errors.
-     * @return the number of bytes read, or -1 if there was an error.
+     * @return the number of bytes read, or -1 if end of stream is reached.
      */
     public abstract int readAt(long position, byte[] buffer, int offset, int size)
             throws IOException;
diff --git a/media/java/android/media/MediaDataSource.java b/media/java/android/media/MediaDataSource.java
index 4ba2120f5b09b..4bdc1adcc3f08 100644
--- a/media/java/android/media/MediaDataSource.java
+++ b/media/java/android/media/MediaDataSource.java
@@ -46,7 +46,7 @@ public abstract class MediaDataSource implements Closeable {
      * @param offset the offset within buffer to read the data into.
      * @param size the number of bytes to read.
      * @throws IOException on fatal errors.
-     * @return the number of bytes read, or -1 if there was an error.
+     * @return the number of bytes read, or -1 if end of stream is reached.
      */
     public abstract int readAt(long position, byte[] buffer, int offset, int size)
             throws IOException;