Do not compare bitrates of audio tracks with different languages.

The last selection criteria is the audio bitrate to prefer higher-quality
streams. We shouldn't apply this criterium though if the languages of the
tracks are different.

Issue:#6335
PiperOrigin-RevId: 265064756

RELEASENOTES.md

@@ -9,6 +9,8 @@
 * Reset `DefaultBandwidthMeter` to initial values on network change.
 * Increase maximum buffer size for video in `DefaultLoadControl` to ensure high
   quality video can be loaded up to the full default buffer duration.
+* Fix audio selection issue where languages are compared by bit rate
+  ([#6335](https://github.com/google/ExoPlayer/issues/6335)).
 
 ### 2.10.4 ###
 

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

@@ -2501,6 +2501,7 @@ public class DefaultTrackSelector extends MappingTrackSelector {
 
     public final boolean isWithinConstraints;
 
+    @Nullable private final String language;
     private final Parameters parameters;
     private final boolean isWithinRendererCapabilities;
     private final int preferredLanguageScore;
@@ -2513,6 +2514,7 @@ public class DefaultTrackSelector extends MappingTrackSelector {
 
     public AudioTrackScore(Format format, Parameters parameters, int formatSupport) {
       this.parameters = parameters;
+      this.language = normalizeUndeterminedLanguageToNull(format.language);
       isWithinRendererCapabilities = isSupported(formatSupport, false);
       preferredLanguageScore = getFormatLanguageScore(format, parameters.preferredAudioLanguage);
       isDefaultSelectionFlag = (format.selectionFlags & C.SELECTION_FLAG_DEFAULT) != 0;
@@ -2580,8 +2582,12 @@ public class DefaultTrackSelector extends MappingTrackSelector {
       if (this.sampleRate != other.sampleRate) {
         return resultSign * compareInts(this.sampleRate, other.sampleRate);
       }
+      if (Util.areEqual(this.language, other.language)) {
+        // Only compare bit rates of tracks with the same or unknown language.
         return resultSign * compareInts(this.bitrate, other.bitrate);
       }
+      return 0;
+    }
   }
 
   /**

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

@@ -719,37 +719,38 @@ public final class DefaultTrackSelectorTest {
   }
 
   /**
-   * Tests that track selector will select audio tracks with higher bit-rate when other factors are
+   * Tests that track selector will select audio tracks with higher bit rate when other factors are
-   * the same, and tracks are within renderer's capabilities.
+   * the same, and tracks are within renderer's capabilities, and have the same language.
    */
   @Test
-  public void testSelectTracksWithinCapabilitiesSelectHigherBitrate() throws Exception {
+  public void selectAudioTracks_withinCapabilities_andSameLanguage_selectsHigherBitrate()
+      throws Exception {
     Format lowerBitrateFormat =
         Format.createAudioSampleFormat(
             "audioFormat",
             MimeTypes.AUDIO_AAC,
-            null,
+            /* codecs= */ null,
-            15000,
+            /* bitrate= */ 15000,
-            Format.NO_VALUE,
+            /* maxInputSize= */ Format.NO_VALUE,
-            2,
+            /* channelCount= */ 2,
-            44100,
+            /* sampleRate= */ 44100,
-            null,
+            /* initializationData= */ null,
-            null,
+            /* drmInitData= */ null,
-            0,
+            /* selectionFlags= */ 0,
-            null);
+            /* language= */ "hi");
     Format higherBitrateFormat =
         Format.createAudioSampleFormat(
             "audioFormat",
             MimeTypes.AUDIO_AAC,
-            null,
+            /* codecs= */ null,
-            30000,
+            /* bitrate= */ 30000,
-            Format.NO_VALUE,
+            /* maxInputSize= */ Format.NO_VALUE,
-            2,
+            /* channelCount= */ 2,
-            44100,
+            /* sampleRate= */ 44100,
-            null,
+            /* initializationData= */ null,
-            null,
+            /* drmInitData= */ null,
-            0,
+            /* selectionFlags= */ 0,
-            null);
+            /* language= */ "hi");
     TrackGroupArray trackGroups = wrapFormats(lowerBitrateFormat, higherBitrateFormat);
 
     TrackSelectorResult result =
@@ -761,14 +762,58 @@ public final class DefaultTrackSelectorTest {
     assertFixedSelection(result.selections.get(0), trackGroups, higherBitrateFormat);
   }
 
+  /**
+   * Tests that track selector will select the first audio track even if other tracks with a
+   * different language have higher bit rates, all other factors are the same, and tracks are within
+   * renderer's capabilities.
+   */
+  @Test
+  public void selectAudioTracks_withinCapabilities_andDifferentLanguage_selectsFirstTrack()
+      throws Exception {
+    Format firstLanguageFormat =
+        Format.createAudioSampleFormat(
+            "audioFormat",
+            MimeTypes.AUDIO_AAC,
+            /* codecs= */ null,
+            /* bitrate= */ 15000,
+            /* maxInputSize= */ Format.NO_VALUE,
+            /* channelCount= */ 2,
+            /* sampleRate= */ 44100,
+            /* initializationData= */ null,
+            /* drmInitData= */ null,
+            /* selectionFlags= */ 0,
+            /* language= */ "hi");
+    Format higherBitrateFormat =
+        Format.createAudioSampleFormat(
+            "audioFormat",
+            MimeTypes.AUDIO_AAC,
+            /* codecs= */ null,
+            /* bitrate= */ 30000,
+            /* maxInputSize= */ Format.NO_VALUE,
+            /* channelCount= */ 2,
+            /* sampleRate= */ 44100,
+            /* initializationData= */ null,
+            /* drmInitData= */ null,
+            /* selectionFlags= */ 0,
+            /* language= */ "te");
+    TrackGroupArray trackGroups = wrapFormats(firstLanguageFormat, higherBitrateFormat);
+
+    TrackSelectorResult result =
+        trackSelector.selectTracks(
+            new RendererCapabilities[] {ALL_AUDIO_FORMAT_SUPPORTED_RENDERER_CAPABILITIES},
+            trackGroups,
+            periodId,
+            TIMELINE);
+    assertFixedSelection(result.selections.get(0), trackGroups, firstLanguageFormat);
+  }
+
   /**
    * Tests that track selector will prefer audio tracks with higher channel count over tracks with
    * higher sample rate when other factors are the same, and tracks are within renderer's
    * capabilities.
    */
   @Test
-  public void testSelectTracksPreferHigherNumChannelBeforeSampleRate()
+  public void testSelectTracksPreferHigherNumChannelBeforeSampleRate() throws Exception {
-      throws Exception {
     Format higherChannelLowerSampleRateFormat =
         Format.createAudioSampleFormat(
             "audioFormat",