Select text track matching selected audio language when selecting forced text tracks

PiperOrigin-RevId: 240133676

library/core/src/main/java/com/google/android/exoplayer2/trackselection/DefaultTrackSelector.java

@@ -1510,6 +1510,7 @@ public class DefaultTrackSelector extends MappingTrackSelector {
     }
 
     AudioTrackScore selectedAudioTrackScore = null;
+    String selectedAudioLanguage = null;
     int selectedAudioRendererIndex = C.INDEX_UNSET;
     for (int i = 0; i < rendererCount; i++) {
       if (C.TRACK_TYPE_AUDIO == mappedTrackInfo.getRendererType(i)) {
@@ -1528,7 +1529,10 @@ public class DefaultTrackSelector extends MappingTrackSelector {
             // score. Clear the selection for that renderer.
             definitions[selectedAudioRendererIndex] = null;
           }
-          definitions[i] = audioSelection.first;
+          TrackSelection.Definition definition = audioSelection.first;
+          definitions[i] = definition;
+          // We assume that audio tracks in the same group have matching language.
+          selectedAudioLanguage = definition.group.getFormat(definition.tracks[0]).language;
           selectedAudioTrackScore = audioSelection.second;
           selectedAudioRendererIndex = i;
         }
@@ -1546,7 +1550,11 @@ public class DefaultTrackSelector extends MappingTrackSelector {
           break;
         case C.TRACK_TYPE_TEXT:
           Pair<TrackSelection.Definition, Integer> textSelection =
-              selectTextTrack(mappedTrackInfo.getTrackGroups(i), rendererFormatSupports[i], params);
+              selectTextTrack(
+                  mappedTrackInfo.getTrackGroups(i),
+                  rendererFormatSupports[i],
+                  params,
+                  selectedAudioLanguage);
           if (textSelection != null && textSelection.second > selectedTextTrackScore) {
             if (selectedTextRendererIndex != C.INDEX_UNSET) {
               // We've already made a selection for another text renderer, but it had a lower score.
@@ -2020,13 +2028,18 @@ public class DefaultTrackSelector extends MappingTrackSelector {
    * @param formatSupport The result of {@link RendererCapabilities#supportsFormat} for each mapped
    *     track, indexed by track group index and track index (in that order).
    * @param params The selector's current constraint parameters.
+   * @param selectedAudioLanguage The language of the selected audio track. May be null if the
+   *     selected audio track declares no language or no audio track was selected.
    * @return The {@link TrackSelection.Definition} and corresponding track score, or null if no
    *     selection was made.
    * @throws ExoPlaybackException If an error occurs while selecting the tracks.
    */
   @Nullable
   protected Pair<TrackSelection.Definition, Integer> selectTextTrack(
-      TrackGroupArray groups, int[][] formatSupport, Parameters params)
+      TrackGroupArray groups,
+      int[][] formatSupport,
+      Parameters params,
+      @Nullable String selectedAudioLanguage)
       throws ExoPlaybackException {
     TrackGroup selectedGroup = null;
     int selectedTrackIndex = 0;
@@ -2047,20 +2060,26 @@ public class DefaultTrackSelector extends MappingTrackSelector {
           if (languageScore > 0
               || (params.selectUndeterminedTextLanguage && formatHasNoLanguage(format))) {
             if (isDefault) {
-              trackScore = 11;
+              trackScore = 13;
             } else if (!isForced) {
               // Prefer non-forced to forced if a preferred text language has been specified. Where
               // both are provided the non-forced track will usually contain the forced subtitles as
               // a subset.
-              trackScore = 8;
+              trackScore = 10;
             } else {
-              trackScore = 5;
+              trackScore = 7;
             }
             trackScore += languageScore;
           } else if (isDefault) {
-            trackScore = 4;
+            trackScore = 6;
           } else if (isForced) {
-            trackScore = 1 + languageScore;
+            int preferredAudioLanguageScore =
+                getFormatLanguageScore(format, params.preferredAudioLanguage);
+            if (preferredAudioLanguageScore > 0) {
+              trackScore = 3 + preferredAudioLanguageScore;
+            } else {
+              trackScore = 1 + getFormatLanguageScore(format, selectedAudioLanguage);
+            }
           } else {
             // Track should not be selected.
             continue;

library/core/src/test/java/com/google/android/exoplayer2/trackselection/DefaultTrackSelectorTest.java

@@ -888,7 +888,7 @@ public final class DefaultTrackSelectorTest {
 
   /** Tests text track selection flags. */
   @Test
-  public void testsTextTrackSelectionFlags() throws ExoPlaybackException {
+  public void testTextTrackSelectionFlags() throws ExoPlaybackException {
     Format forcedOnly = buildTextFormat("forcedOnly", "eng", C.SELECTION_FLAG_FORCED);
     Format forcedDefault =
         buildTextFormat("forcedDefault", "eng", C.SELECTION_FLAG_FORCED | C.SELECTION_FLAG_DEFAULT);
@@ -968,6 +968,55 @@ public final class DefaultTrackSelectorTest {
   }
 
   /**
+   * Tests that the default track selector will select a forced text track matching the selected
+   * audio language when no text language preferences match.
+   */
+  @Test
+  public void testSelectingForcedTextTrackMatchesAudioLanguage() throws ExoPlaybackException {
+    Format forcedEnglish =
+        buildTextFormat(/* id= */ "forcedEnglish", /* language= */ "eng", C.SELECTION_FLAG_FORCED);
+    Format forcedGerman =
+        buildTextFormat(/* id= */ "forcedGerman", /* language= */ "deu", C.SELECTION_FLAG_FORCED);
+    Format audio = buildAudioFormat(/* id= */ "audio");
+    Format germanAudio =
+        buildAudioFormat(
+            /* id= */ "germanAudio",
+            MimeTypes.AUDIO_AAC,
+            /* bitrate= */ Format.NO_VALUE,
+            "deu",
+            /* selectionFlags= */ 0,
+            /* channelCount= */ Format.NO_VALUE,
+            /* sampleRate= */ Format.NO_VALUE);
+
+    RendererCapabilities[] rendererCapabilities =
+        new RendererCapabilities[] {
+          ALL_AUDIO_FORMAT_SUPPORTED_RENDERER_CAPABILITIES,
+          ALL_TEXT_FORMAT_SUPPORTED_RENDERER_CAPABILITIES
+        };
+
+    // The audio declares no language. The first forced text track should be selected.
+    TrackGroupArray trackGroups = wrapFormats(audio, forcedEnglish, forcedGerman);
+    TrackSelectorResult result =
+        trackSelector.selectTracks(rendererCapabilities, trackGroups, periodId, TIMELINE);
+    assertFixedSelection(result.selections.get(1), trackGroups, forcedEnglish);
+
+    // Ditto.
+    trackGroups = wrapFormats(audio, forcedGerman, forcedEnglish);
+    result = trackSelector.selectTracks(rendererCapabilities, trackGroups, periodId, TIMELINE);
+    assertFixedSelection(result.selections.get(1), trackGroups, forcedGerman);
+
+    // The audio declares german. The german forced track should be selected.
+    trackGroups = wrapFormats(germanAudio, forcedGerman, forcedEnglish);
+    result = trackSelector.selectTracks(rendererCapabilities, trackGroups, periodId, TIMELINE);
+    assertFixedSelection(result.selections.get(1), trackGroups, forcedGerman);
+
+    // Ditto
+    trackGroups = wrapFormats(germanAudio, forcedEnglish, forcedGerman);
+    result = trackSelector.selectTracks(rendererCapabilities, trackGroups, periodId, TIMELINE);
+    assertFixedSelection(result.selections.get(1), trackGroups, forcedGerman);
+  }
+
+  /**
    * Tests that the default track selector will select a text track with undetermined language if no
    * text track with the preferred language is available but
    * {@link Parameters#selectUndeterminedTextLanguage} is true.