diff --git a/libraries/muxer/src/main/java/androidx/media3/muxer/Mp4Muxer.java b/libraries/muxer/src/main/java/androidx/media3/muxer/Mp4Muxer.java
index 5c17af7fb2..69eeef217a 100644
--- a/libraries/muxer/src/main/java/androidx/media3/muxer/Mp4Muxer.java
+++ b/libraries/muxer/src/main/java/androidx/media3/muxer/Mp4Muxer.java
@@ -237,6 +237,9 @@ public final class Mp4Muxer {
   /**
    * Writes encoded sample data.
    *
+   * <p>The samples are cached and are written in batches so the caller must not change/release the
+   * {@link ByteBuffer} and the {@link BufferInfo} after calling this method.
+   *
    * @param trackToken The {@link TrackToken} for which this sample is being written.
    * @param byteBuffer The encoded sample.
    * @param bufferInfo The {@link BufferInfo} related to this sample.
diff --git a/libraries/muxer/src/main/java/androidx/media3/muxer/Mp4Writer.java b/libraries/muxer/src/main/java/androidx/media3/muxer/Mp4Writer.java
index ce42aee2bb..e4a78b983b 100644
--- a/libraries/muxer/src/main/java/androidx/media3/muxer/Mp4Writer.java
+++ b/libraries/muxer/src/main/java/androidx/media3/muxer/Mp4Writer.java
@@ -379,19 +379,7 @@ import java.util.concurrent.atomic.AtomicBoolean;
       // Skip empty samples.
       // TODO: b/279931840 - Confirm whether muxer should throw when writing empty samples.
       if (byteBuffer.remaining() > 0) {
-        // Copy sample data and release the original buffer.
-        ByteBuffer byteBufferCopy = ByteBuffer.allocateDirect(byteBuffer.remaining());
-        byteBufferCopy.put(byteBuffer);
-        byteBufferCopy.rewind();
-
-        BufferInfo bufferInfoCopy = new BufferInfo();
-        bufferInfoCopy.set(
-            /* newOffset= */ byteBufferCopy.position(),
-            /* newSize= */ byteBufferCopy.remaining(),
-            bufferInfo.presentationTimeUs,
-            bufferInfo.flags);
-
-        pendingSamples.addLast(Pair.create(bufferInfoCopy, byteBufferCopy));
+        pendingSamples.addLast(Pair.create(bufferInfo, byteBuffer));
         doInterleave();
       }
     }
diff --git a/libraries/transformer/src/main/java/androidx/media3/transformer/InAppMuxer.java b/libraries/transformer/src/main/java/androidx/media3/transformer/InAppMuxer.java
index be50452c25..5fbc1b3b04 100644
--- a/libraries/transformer/src/main/java/androidx/media3/transformer/InAppMuxer.java
+++ b/libraries/transformer/src/main/java/androidx/media3/transformer/InAppMuxer.java
@@ -165,7 +165,19 @@ public final class InAppMuxer implements Muxer {
         data.position(), size, presentationTimeUs, TransformerUtil.getMediaCodecFlags(flags));
 
     try {
-      mp4Muxer.writeSampleData(trackTokenList.get(trackIndex), data, bufferInfo);
+      // Copy sample data and release the original buffer.
+      ByteBuffer byteBufferCopy = ByteBuffer.allocateDirect(data.remaining());
+      byteBufferCopy.put(data);
+      byteBufferCopy.rewind();
+
+      BufferInfo bufferInfoCopy = new BufferInfo();
+      bufferInfoCopy.set(
+          /* newOffset= */ byteBufferCopy.position(),
+          /* newSize= */ byteBufferCopy.remaining(),
+          bufferInfo.presentationTimeUs,
+          bufferInfo.flags);
+
+      mp4Muxer.writeSampleData(trackTokenList.get(trackIndex), byteBufferCopy, bufferInfoCopy);
     } catch (IOException e) {
       throw new MuxerException(
           "Failed to write sample for trackIndex="