Handle metadata failing to decode in MetadataRenderer

Issue: #5149
PiperOrigin-RevId: 223121651

RELEASENOTES.md

@@ -20,6 +20,8 @@
   ([#4690](https://github.com/google/ExoPlayer/issues/4690)).
   ([#4690](https://github.com/google/ExoPlayer/issues/4690)).
 * Fix issue with applying the `show_buffering` attribute in `PlayerView`
 * Fix issue with applying the `show_buffering` attribute in `PlayerView`
   ([#5139](https://github.com/google/ExoPlayer/issues/5139)).
   ([#5139](https://github.com/google/ExoPlayer/issues/5139)).
+* Fix issue where null `Metadata` was output when it failed to decode
+  ([#5149](https://github.com/google/ExoPlayer/issues/5149)).
 
 
 ### 2.9.1 ###
 ### 2.9.1 ###
 
 

library/core/src/main/java/com/google/android/exoplayer2/metadata/MetadataRenderer.java

@@ -129,12 +129,15 @@ public final class MetadataRenderer extends BaseRenderer implements Callback {
           buffer.subsampleOffsetUs = formatHolder.format.subsampleOffsetUs;
           buffer.subsampleOffsetUs = formatHolder.format.subsampleOffsetUs;
           buffer.flip();
           buffer.flip();
           int index = (pendingMetadataIndex + pendingMetadataCount) % MAX_PENDING_METADATA_COUNT;
           int index = (pendingMetadataIndex + pendingMetadataCount) % MAX_PENDING_METADATA_COUNT;
-          pendingMetadata[index] = decoder.decode(buffer);
+          Metadata metadata = decoder.decode(buffer);
+          if (metadata != null) {
+            pendingMetadata[index] = metadata;
             pendingMetadataTimestamps[index] = buffer.timeUs;
             pendingMetadataTimestamps[index] = buffer.timeUs;
             pendingMetadataCount++;
             pendingMetadataCount++;
           }
           }
         }
         }
       }
       }
+    }
 
 
     if (pendingMetadataCount > 0 && pendingMetadataTimestamps[pendingMetadataIndex] <= positionUs) {
     if (pendingMetadataCount > 0 && pendingMetadataTimestamps[pendingMetadataIndex] <= positionUs) {
       invokeRenderer(pendingMetadata[pendingMetadataIndex]);
       invokeRenderer(pendingMetadata[pendingMetadataIndex]);