diff --git a/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/Muxer.java b/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/Muxer.java
index 72e5f0f6b8..b00fbadfd5 100644
--- a/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/Muxer.java
+++ b/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/Muxer.java
@@ -28,8 +28,8 @@ import java.nio.ByteBuffer;
  * <p>Query whether {@link #supportsSampleMimeType(String) sample MIME types are supported} and
  * {@link #addTrack(Format) add all tracks}, then {@link #writeSampleData(int, ByteBuffer, boolean,
  * long) write sample data} to mux samples. Once any sample data has been written, it is not
- * possible to add tracks. After writing all sample data, {@link #release() release} the instance to
- * finish writing to the output and return any resources to the system.
+ * possible to add tracks. After writing all sample data, {@link #release(boolean) release} the
+ * instance to finish writing to the output and return any resources to the system.
  */
 /* package */ interface Muxer {
 
diff --git a/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/Transformer.java b/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/Transformer.java
index aa0437daba..57583c79ad 100644
--- a/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/Transformer.java
+++ b/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/Transformer.java
@@ -204,8 +204,10 @@ public final class Transformer {
     }
 
     /**
-     * Sets the MIME type of the output. The default value is {@link MimeTypes#VIDEO_MP4}. Supported
-     * values are:
+     * Sets the MIME type of the output. The default value is {@link MimeTypes#VIDEO_MP4}. The
+     * output MIME type should be supported by the {@link
+     * Muxer.Factory#supportsOutputMimeType(String) muxer}. Values supported by the default {@link
+     * FrameworkMuxer} are:
      *
      * <ul>
      *   <li>{@link MimeTypes#VIDEO_MP4}
@@ -261,7 +263,8 @@ public final class Transformer {
     }
 
     /**
-     * Sets the factory for muxers that write the media container.
+     * Sets the factory for muxers that write the media container. The default value is a {@link
+     * FrameworkMuxer.Factory}.
      *
      * @param muxerFactory A {@link Muxer.Factory}.
      * @return This builder.
@@ -407,7 +410,8 @@ public final class Transformer {
    * sources}, the highest bitrate video and audio streams are selected.
    *
    * @param mediaItem The {@link MediaItem} to transform. The supported sample formats depend on the
-   *     output container format and are described in {@link MediaMuxer#addTrack(MediaFormat)}.
+   *     {@link Muxer} and on the output container format. For the {@link FrameworkMuxer}, they are
+   *     described in {@link MediaMuxer#addTrack(MediaFormat)}.
    * @param path The path to the output file.
    * @throws IllegalArgumentException If the path is invalid.
    * @throws IllegalStateException If this method is called from the wrong thread.
@@ -431,7 +435,8 @@ public final class Transformer {
    * sources}, the highest bitrate video and audio streams are selected.
    *
    * @param mediaItem The {@link MediaItem} to transform. The supported sample formats depend on the
-   *     output container format and are described in {@link MediaMuxer#addTrack(MediaFormat)}.
+   *     {@link Muxer} and on the output container format. For the {@link FrameworkMuxer}, they are
+   *     described in {@link MediaMuxer#addTrack(MediaFormat)}.
    * @param parcelFileDescriptor A readable and writable {@link ParcelFileDescriptor} of the output.
    *     The file referenced by this ParcelFileDescriptor should not be used before the
    *     transformation is completed. It is the responsibility of the caller to close the
diff --git a/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/TransformerAudioRenderer.java b/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/TransformerAudioRenderer.java
index 6198054aa2..6504151db5 100644
--- a/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/TransformerAudioRenderer.java
+++ b/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/TransformerAudioRenderer.java
@@ -222,8 +222,8 @@ import java.nio.ByteBuffer;
   }
 
   /**
-   * Attempts to process decoder output audio, and returns whether it may be possible to process
-   * more data immediately by calling this method again.
+   * Attempts to process decoder output data, and returns whether it may be possible to process more
+   * data immediately by calling this method again.
    */
   private boolean drainDecoderToFeedSonic() {
     MediaCodecAdapterWrapper decoder = checkNotNull(this.decoder);