Don't inform of static metadata changes if they are all empty.

The current code creates placeholder metadata elements if there is no
static metadata. This causes onStaticMetadataChanged callbacks even
if there is no metadata.

Instead, we can keep the empty list as the static metadata is already
documented to be an empty list if the metadata is unavailable.

#exofixit

PiperOrigin-RevId: 344071639

library/core/src/main/java/com/google/android/exoplayer2/ExoPlayerImpl.java

@@ -1259,7 +1259,7 @@ import java.util.concurrent.TimeoutException;
               /* totalBufferedDurationUs= */ 0,
               TrackGroupArray.EMPTY,
               emptyTrackSelectorResult,
-              ImmutableList.of());
+              /* staticMetadata= */ ImmutableList.of());
       playbackInfo = playbackInfo.copyWithLoadingMediaPeriodId(dummyMediaPeriodId);
       playbackInfo.bufferedPositionUs = playbackInfo.positionUs;
       return playbackInfo;

library/core/src/main/java/com/google/android/exoplayer2/ExoPlayerImplInternal.java

@@ -2247,14 +2247,20 @@ import java.util.concurrent.atomic.AtomicBoolean;
   private ImmutableList<Metadata> extractMetadataFromTrackSelectionArray(
       TrackSelectionArray trackSelectionArray) {
     ImmutableList.Builder<Metadata> result = new ImmutableList.Builder<>();
+    boolean seenNonEmptyMetadata = false;
     for (int i = 0; i < trackSelectionArray.length; i++) {
       @Nullable TrackSelection trackSelection = trackSelectionArray.get(i);
       if (trackSelection != null) {
         Format format = trackSelection.getFormat(/* index= */ 0);
-        result.add(format.metadata == null ? new Metadata() : format.metadata);
+        if (format.metadata == null) {
+          result.add(new Metadata());
+        } else {
+          result.add(format.metadata);
+          seenNonEmptyMetadata = true;
+        }
       }
     }
-    return result.build();
+    return seenNonEmptyMetadata ? result.build() : ImmutableList.of();
   }
 
   private void enableRenderers() throws ExoPlaybackException {

library/core/src/main/java/com/google/android/exoplayer2/Player.java

@@ -512,8 +512,8 @@ public interface Player {
      *
      * <p>The provided {@code metadataList} is an immutable list of {@link Metadata} instances,
      * where the elements correspond to the {@link #getCurrentTrackSelections() current track
-     * selections}, or an empty list if there are no track selections or the implementation does not
+     * selections}, or an empty list if there are no track selections or the selected tracks contain
-     * support metadata.
+     * no static metadata.
      *
      * <p>The metadata is considered static in the sense that it comes from the tracks' declared
      * Formats, rather than being timed (or dynamic) metadata, which is represented within a
@@ -1433,7 +1433,7 @@ public interface Player {
    *
    * <p>The returned {@code metadataList} is an immutable list of {@link Metadata} instances, where
    * the elements correspond to the {@link #getCurrentTrackSelections() current track selections},
-   * or an empty list if there are no track selections or the implementation does not support
+   * or an empty list if there are no track selections or the selected tracks contain no static
    * metadata.
    *
    * <p>This metadata is considered static in that it comes from the tracks' declared Formats,

library/core/src/main/java/com/google/android/exoplayer2/analytics/AnalyticsListener.java

@@ -604,7 +604,7 @@ public interface AnalyticsListener {
    * <p>The provided {@code metadataList} is an immutable list of {@link Metadata} instances, where
    * the elements correspond to the current track selections (as returned by {@link
    * #onTracksChanged(EventTime, TrackGroupArray, TrackSelectionArray)}, or an empty list if there
-   * are no track selections or the implementation does not support metadata.
+   * are no track selections or the selected tracks contain no static metadata.
    *
    * <p>The metadata is considered static in the sense that it comes from the tracks' declared
    * Formats, rather than being timed (or dynamic) metadata, which is represented within a metadata

library/core/src/test/java/com/google/android/exoplayer2/ExoPlayerTest.java

@@ -8260,8 +8260,6 @@ public final class ExoPlayerTest {
     Format videoFormat =
         new Format.Builder()
             .setSampleMimeType(MimeTypes.VIDEO_H264)
-            .setWidth(1920)
-            .setHeight(720)
             .setMetadata(
                 new Metadata(
                     new TextInformationFrame(
@@ -8269,11 +8267,9 @@ public final class ExoPlayerTest {
                         /* description= */ "Video",
                         /* value= */ "Video track name")))
             .build();
-
     Format audioFormat =
         new Format.Builder()
             .setSampleMimeType(MimeTypes.AUDIO_AAC)
-            .setSampleRate(44_000)
             .setMetadata(
                 new Metadata(
                     new TextInformationFrame(
@@ -8281,9 +8277,7 @@ public final class ExoPlayerTest {
                         /* description= */ "Audio",
                         /* value= */ "Audio track name")))
             .build();
-
     EventListener eventListener = mock(EventListener.class);
-
     Timeline fakeTimeline =
         new FakeTimeline(
             new TimelineWindowDefinition(
@@ -8295,14 +8289,38 @@ public final class ExoPlayerTest {
     player.prepare();
     player.play();
     runUntilPlaybackState(player, Player.STATE_ENDED);
+    List<Metadata> metadata = player.getCurrentStaticMetadata();
+    player.release();
 
-    assertThat(player.getCurrentStaticMetadata())
+    assertThat(metadata).containsExactly(videoFormat.metadata, audioFormat.metadata).inOrder();
-        .containsExactly(videoFormat.metadata, audioFormat.metadata)
-        .inOrder();
     verify(eventListener)
         .onStaticMetadataChanged(ImmutableList.of(videoFormat.metadata, audioFormat.metadata));
   }
 
+  @Test
+  public void staticMetadata_callbackIsNotCalledWhenMetadataEmptyAndGetterReturnsEmptyList()
+      throws Exception {
+    Format videoFormat = new Format.Builder().setSampleMimeType(MimeTypes.VIDEO_H264).build();
+    Format audioFormat = new Format.Builder().setSampleMimeType(MimeTypes.AUDIO_AAC).build();
+    EventListener eventListener = mock(EventListener.class);
+    Timeline fakeTimeline =
+        new FakeTimeline(
+            new TimelineWindowDefinition(
+                /* isSeekable= */ true, /* isDynamic= */ false, /* durationUs= */ 100000));
+    SimpleExoPlayer player = new TestExoPlayerBuilder(context).build();
+
+    player.setMediaSource(new FakeMediaSource(fakeTimeline, videoFormat, audioFormat));
+    player.addListener(eventListener);
+    player.prepare();
+    player.play();
+    runUntilPlaybackState(player, Player.STATE_ENDED);
+    List<Metadata> metadata = player.getCurrentStaticMetadata();
+    player.release();
+
+    assertThat(metadata).isEmpty();
+    verify(eventListener, never()).onStaticMetadataChanged(any());
+  }
+
   @Test
   public void targetLiveOffsetInMedia_adjustsLiveOffsetToTargetOffset() throws Exception {
     long windowStartUnixTimeMs = 987_654_321_000L;

library/core/src/test/java/com/google/android/exoplayer2/analytics/AnalyticsCollectorTest.java

@@ -40,7 +40,6 @@ import static com.google.android.exoplayer2.analytics.AnalyticsListener.EVENT_PL
 import static com.google.android.exoplayer2.analytics.AnalyticsListener.EVENT_PLAY_WHEN_READY_CHANGED;
 import static com.google.android.exoplayer2.analytics.AnalyticsListener.EVENT_POSITION_DISCONTINUITY;
 import static com.google.android.exoplayer2.analytics.AnalyticsListener.EVENT_RENDERED_FIRST_FRAME;
-import static com.google.android.exoplayer2.analytics.AnalyticsListener.EVENT_STATIC_METADATA_CHANGED;
 import static com.google.android.exoplayer2.analytics.AnalyticsListener.EVENT_TIMELINE_CHANGED;
 import static com.google.android.exoplayer2.analytics.AnalyticsListener.EVENT_TRACKS_CHANGED;
 import static com.google.android.exoplayer2.analytics.AnalyticsListener.EVENT_VIDEO_DECODER_INITIALIZED;
@@ -1714,10 +1713,6 @@ public final class AnalyticsCollectorTest {
         ArgumentCaptor.forClass(AnalyticsListener.EventTime.class);
     verify(listener, atLeastOnce())
         .onAudioEnabled(individualAudioEnabledEventTimes.capture(), any());
-    ArgumentCaptor<AnalyticsListener.EventTime> individualStaticMetadataChangedEventTimes =
-        ArgumentCaptor.forClass(AnalyticsListener.EventTime.class);
-    verify(listener, atLeastOnce())
-        .onStaticMetadataChanged(individualStaticMetadataChangedEventTimes.capture(), any());
     ArgumentCaptor<AnalyticsListener.EventTime> individualDownstreamFormatChangedEventTimes =
         ArgumentCaptor.forClass(AnalyticsListener.EventTime.class);
     verify(listener, atLeastOnce())
@@ -1839,9 +1834,6 @@ public final class AnalyticsCollectorTest {
     assertThat(individualAudioEnabledEventTimes.getAllValues())
         .containsAtLeastElementsIn(onEventsEventTimes.get(EVENT_AUDIO_ENABLED))
         .inOrder();
-    assertThat(individualStaticMetadataChangedEventTimes.getAllValues())
-        .containsAtLeastElementsIn(onEventsEventTimes.get(EVENT_STATIC_METADATA_CHANGED))
-        .inOrder();
     assertThat(individualDownstreamFormatChangedEventTimes.getAllValues())
         .containsAtLeastElementsIn(onEventsEventTimes.get(EVENT_DOWNSTREAM_FORMAT_CHANGED))
         .inOrder();