diff --git a/demos/transformer/src/main/java/androidx/media3/demo/transformer/ConfigurationActivity.java b/demos/transformer/src/main/java/androidx/media3/demo/transformer/ConfigurationActivity.java
index 470ec5f18b..4d41a588a5 100644
--- a/demos/transformer/src/main/java/androidx/media3/demo/transformer/ConfigurationActivity.java
+++ b/demos/transformer/src/main/java/androidx/media3/demo/transformer/ConfigurationActivity.java
@@ -77,6 +77,7 @@ public final class ConfigurationActivity extends AppCompatActivity {
   public static final String ENABLE_ANALYZER_MODE = "enable_analyzer_mode";
   public static final String ENABLE_DEBUG_PREVIEW = "enable_debug_preview";
   public static final String ABORT_SLOW_EXPORT = "abort_slow_export";
+  public static final String USE_MEDIA3_MUXER = "use_media3_muxer";
   public static final String PRODUCE_FRAGMENTED_MP4 = "produce_fragmented_mp4";
   public static final String HDR_MODE = "hdr_mode";
   public static final String AUDIO_EFFECTS_SELECTIONS = "audio_effects_selections";
@@ -172,6 +173,7 @@ public final class ConfigurationActivity extends AppCompatActivity {
   private CheckBox enableDebugPreviewCheckBox;
   private CheckBox enableDebugTracingCheckBox;
   private CheckBox abortSlowExportCheckBox;
+  private CheckBox useMedia3Muxer;
   private CheckBox produceFragmentedMp4CheckBox;
   private Spinner hdrModeSpinner;
   private Button selectAudioEffectsButton;
@@ -298,6 +300,7 @@ public final class ConfigurationActivity extends AppCompatActivity {
         (buttonView, isChecked) -> DebugTraceUtil.enableTracing = isChecked);
 
     abortSlowExportCheckBox = findViewById(R.id.abort_slow_export_checkbox);
+    useMedia3Muxer = findViewById(R.id.use_media3_muxer_checkbox);
     produceFragmentedMp4CheckBox = findViewById(R.id.produce_fragmented_mp4_checkbox);
 
     ArrayAdapter<String> hdrModeAdapter =
@@ -389,6 +392,7 @@ public final class ConfigurationActivity extends AppCompatActivity {
     bundle.putBoolean(ENABLE_ANALYZER_MODE, enableAnalyzerModeCheckBox.isChecked());
     bundle.putBoolean(ENABLE_DEBUG_PREVIEW, enableDebugPreviewCheckBox.isChecked());
     bundle.putBoolean(ABORT_SLOW_EXPORT, abortSlowExportCheckBox.isChecked());
+    bundle.putBoolean(USE_MEDIA3_MUXER, useMedia3Muxer.isChecked());
     bundle.putBoolean(PRODUCE_FRAGMENTED_MP4, produceFragmentedMp4CheckBox.isChecked());
     String selectedHdrMode = String.valueOf(hdrModeSpinner.getSelectedItem());
     bundle.putInt(HDR_MODE, HDR_MODE_DESCRIPTIONS.get(selectedHdrMode));
diff --git a/demos/transformer/src/main/java/androidx/media3/demo/transformer/TransformerActivity.java b/demos/transformer/src/main/java/androidx/media3/demo/transformer/TransformerActivity.java
index e27fa22351..963f08c892 100644
--- a/demos/transformer/src/main/java/androidx/media3/demo/transformer/TransformerActivity.java
+++ b/demos/transformer/src/main/java/androidx/media3/demo/transformer/TransformerActivity.java
@@ -318,6 +318,9 @@ public final class TransformerActivity extends AppCompatActivity {
       }
 
       Muxer.Factory muxerFactory = new DefaultMuxer.Factory();
+      if (bundle.getBoolean(ConfigurationActivity.USE_MEDIA3_MUXER)) {
+        muxerFactory = new InAppMuxer.Factory.Builder().build();
+      }
       if (bundle.getBoolean(ConfigurationActivity.PRODUCE_FRAGMENTED_MP4)) {
         muxerFactory = new InAppMuxer.Factory.Builder().setOutputFragmentedMp4(true).build();
       }
diff --git a/demos/transformer/src/main/res/layout/configuration_activity.xml b/demos/transformer/src/main/res/layout/configuration_activity.xml
index e69403202b..bc2997b184 100644
--- a/demos/transformer/src/main/res/layout/configuration_activity.xml
+++ b/demos/transformer/src/main/res/layout/configuration_activity.xml
@@ -235,6 +235,15 @@
           android:id="@+id/abort_slow_export_checkbox"
           android:layout_gravity="end"/>
       </TableRow>
+      <TableRow
+        android:layout_weight="1">
+        <TextView
+          android:layout_gravity="center_vertical"
+          android:text="@string/use_media3_muxer" />
+        <CheckBox
+          android:id="@+id/use_media3_muxer_checkbox"
+          android:layout_gravity="end"/>
+      </TableRow>
       <TableRow
         android:layout_weight="1">
         <TextView
diff --git a/demos/transformer/src/main/res/values/strings.xml b/demos/transformer/src/main/res/values/strings.xml
index 4a77884980..5e6faca1c8 100644
--- a/demos/transformer/src/main/res/values/strings.xml
+++ b/demos/transformer/src/main/res/values/strings.xml
@@ -32,6 +32,7 @@
   <string name="enable_debug_preview" translatable="false">Enable debug preview</string>
   <string name="enable_debug_tracing" translatable="false">Enable debug tracing</string>
   <string name="abort_slow_export" translatable="false">Abort slow export</string>
+  <string name="use_media3_muxer" translatable="false">Use Media3 muxer</string>
   <string name="produce_fragmented_mp4" translatable="false">Produce fragmented MP4</string>
   <string name="trim" translatable="false">Trim</string>
   <string name="hdr_mode" translatable="false">HDR mode</string>