diff --git a/RELEASENOTES.md b/RELEASENOTES.md
index 711b3c4be0..5839a0f7e4 100644
--- a/RELEASENOTES.md
+++ b/RELEASENOTES.md
@@ -66,6 +66,9 @@
         `Surface` in `configure` and calls to a new method `detachOutputSurface`
         to remove a previously set `Surface` if the codec supports this
         (`MediaCodecInfo.detachedSurfaceSupported`).
+    *   Use `MediaCodecAdapter` supplied pixel aspect ratio values if provided
+        when processing `onOutputFormatChanged`
+        ([#1371](https://github.com/androidx/media/pull/1371)).
 *   Text:
     *   Add a custom `VoiceSpan` and populate it for
         [WebVTT voice spans](https://www.w3.org/TR/webvtt1/#webvtt-cue-voice-span)
diff --git a/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/video/MediaCodecVideoRenderer.java b/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/video/MediaCodecVideoRenderer.java
index 1c4b727d69..a7c31e671e 100644
--- a/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/video/MediaCodecVideoRenderer.java
+++ b/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/video/MediaCodecVideoRenderer.java
@@ -1342,7 +1342,17 @@ public class MediaCodecVideoRenderer extends MediaCodecRenderer
               ? mediaFormat.getInteger(KEY_CROP_BOTTOM) - mediaFormat.getInteger(KEY_CROP_TOP) + 1
               : mediaFormat.getInteger(MediaFormat.KEY_HEIGHT);
     }
+
     pixelWidthHeightRatio = format.pixelWidthHeightRatio;
+    if (Util.SDK_INT >= 30
+        && mediaFormat != null
+        && mediaFormat.containsKey(MediaFormat.KEY_PIXEL_ASPECT_RATIO_WIDTH)
+        && mediaFormat.containsKey(MediaFormat.KEY_PIXEL_ASPECT_RATIO_HEIGHT)) {
+      pixelWidthHeightRatio =
+          (float) mediaFormat.getInteger(MediaFormat.KEY_PIXEL_ASPECT_RATIO_WIDTH)
+              / mediaFormat.getInteger(MediaFormat.KEY_PIXEL_ASPECT_RATIO_HEIGHT);
+    }
+
     // The decoder applies the rotation when rendering to the surface. For 90 and 270 degree
     // rotations, we need to flip the width, height and pixel aspect ratio to reflect the rotation
     // that was applied.
diff --git a/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/video/MediaCodecVideoRendererTest.java b/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/video/MediaCodecVideoRendererTest.java
index 7f92d7efad..1954a14697 100644
--- a/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/video/MediaCodecVideoRendererTest.java
+++ b/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/video/MediaCodecVideoRendererTest.java
@@ -50,6 +50,7 @@ import androidx.media3.common.MimeTypes;
 import androidx.media3.common.TrackGroup;
 import androidx.media3.common.VideoSize;
 import androidx.media3.common.util.Clock;
+import androidx.media3.common.util.Util;
 import androidx.media3.decoder.CryptoInfo;
 import androidx.media3.exoplayer.DecoderCounters;
 import androidx.media3.exoplayer.ExoPlaybackException;
@@ -100,6 +101,7 @@ import org.mockito.Mock;
 import org.mockito.junit.MockitoJUnit;
 import org.mockito.junit.MockitoRule;
 import org.robolectric.Shadows;
+import org.robolectric.annotation.Config;
 import org.robolectric.shadows.ShadowDisplay;
 import org.robolectric.shadows.ShadowLooper;
 import org.robolectric.shadows.ShadowSystemClock;
@@ -114,6 +116,7 @@ public class MediaCodecVideoRendererTest {
           .setSampleMimeType(MimeTypes.VIDEO_H264)
           .setWidth(1920)
           .setHeight(1080)
+          .setPixelWidthHeightRatio(1.0f)
           .build();
 
   private static final TrackGroup TRACK_GROUP_H264 = new TrackGroup(VIDEO_H264);
@@ -747,6 +750,84 @@ public class MediaCodecVideoRendererTest {
             new VideoSize(VIDEO_H264.width, VIDEO_H264.height, VIDEO_H264.pixelWidthHeightRatio));
   }
 
+  @Config(minSdk = 30)
+  @Test
+  public void
+      render_withMediaCodecModifyingPixelAspectRatioWidthHeight_sendsVideoSizeChangeWithMediaFormatValues()
+          throws Exception {
+    MediaCodecAdapter.Factory codecAdapterFactory =
+        configuration ->
+            new ForwardingSynchronousMediaCodecAdapter(
+                new SynchronousMediaCodecAdapter.Factory().createAdapter(configuration)) {
+              @Override
+              public MediaFormat getOutputFormat() {
+                MediaFormat mediaFormat = adapter.getOutputFormat();
+                if (Util.SDK_INT >= 30) {
+                  // Change to 9:16 Ratio
+                  mediaFormat.setInteger(MediaFormat.KEY_PIXEL_ASPECT_RATIO_WIDTH, 9);
+                  mediaFormat.setInteger(MediaFormat.KEY_PIXEL_ASPECT_RATIO_HEIGHT, 16);
+                }
+                return mediaFormat;
+              }
+            };
+    MediaCodecVideoRenderer mediaCodecVideoRendererWithCustomAdapter =
+        new MediaCodecVideoRenderer(
+            ApplicationProvider.getApplicationContext(),
+            codecAdapterFactory,
+            mediaCodecSelector,
+            /* allowedJoiningTimeMs= */ 0,
+            /* enableDecoderFallback= */ false,
+            /* eventHandler= */ new Handler(testMainLooper),
+            /* eventListener= */ eventListener,
+            /* maxDroppedFramesToNotify= */ 1) {
+          @Override
+          protected @Capabilities int supportsFormat(
+              MediaCodecSelector mediaCodecSelector, Format format) {
+            return RendererCapabilities.create(C.FORMAT_HANDLED);
+          }
+        };
+    mediaCodecVideoRendererWithCustomAdapter.init(/* index= */ 0, PlayerId.UNSET, Clock.DEFAULT);
+    mediaCodecVideoRendererWithCustomAdapter.handleMessage(
+        Renderer.MSG_SET_VIDEO_OUTPUT, new Surface(new SurfaceTexture(/* texName= */ 0)));
+    FakeSampleStream fakeSampleStream =
+        new FakeSampleStream(
+            new DefaultAllocator(/* trimOnReset= */ true, /* individualAllocationSize= */ 1024),
+            /* mediaSourceEventDispatcher= */ null,
+            DrmSessionManager.DRM_UNSUPPORTED,
+            new DrmSessionEventListener.EventDispatcher(),
+            /* initialFormat= */ VIDEO_H264,
+            ImmutableList.of(
+                oneByteSample(/* timeUs= */ 0, C.BUFFER_FLAG_KEY_FRAME), END_OF_STREAM_ITEM));
+    fakeSampleStream.writeData(/* startPositionUs= */ 0);
+    mediaCodecVideoRendererWithCustomAdapter.enable(
+        RendererConfiguration.DEFAULT,
+        new Format[] {VIDEO_H264},
+        fakeSampleStream,
+        /* positionUs= */ 0,
+        /* joining= */ false,
+        /* mayRenderStartOfStream= */ true,
+        /* startPositionUs= */ 0,
+        /* offsetUs= */ 0,
+        new MediaSource.MediaPeriodId(new Object()));
+    mediaCodecVideoRendererWithCustomAdapter.setCurrentStreamFinal();
+    mediaCodecVideoRendererWithCustomAdapter.start();
+
+    int positionUs = 0;
+    do {
+      mediaCodecVideoRendererWithCustomAdapter.render(
+          positionUs, SystemClock.elapsedRealtime() * 1000);
+      positionUs += 10;
+    } while (!mediaCodecVideoRendererWithCustomAdapter.isEnded());
+    shadowOf(testMainLooper).idle();
+
+    verify(eventListener)
+        .onVideoSizeChanged(
+            new VideoSize(
+                VIDEO_H264.width,
+                VIDEO_H264.height,
+                /* pixelWidthHeightRatio= */ VIDEO_H264.pixelWidthHeightRatio * (9.0f / 16.0f)));
+  }
+
   @Test
   public void
       render_withMultipleQueued_sendsVideoSizeChangedWithCorrectPixelAspectRatioWhenMultipleQueued()
@@ -1903,7 +1984,7 @@ public class MediaCodecVideoRendererTest {
 
   private abstract static class ForwardingSynchronousMediaCodecAdapter
       implements MediaCodecAdapter {
-    private final MediaCodecAdapter adapter;
+    protected final MediaCodecAdapter adapter;
 
     ForwardingSynchronousMediaCodecAdapter(MediaCodecAdapter adapter) {
       this.adapter = adapter;