Use role flags in DefaultTrackNameProvider.

Also make combination of language and role flags the default over the label,
as it's more readable and auto-translated into other languages.

PiperOrigin-RevId: 240801070

library/ui/src/main/java/com/google/android/exoplayer2/ui/DefaultTrackNameProvider.java

@@ -39,15 +39,17 @@ public class DefaultTrackNameProvider implements TrackNameProvider {
     String trackName;
     int trackType = inferPrimaryTrackType(format);
     if (trackType == C.TRACK_TYPE_VIDEO) {
-      trackName = joinWithSeparator(buildResolutionString(format), buildBitrateString(format));
+      trackName =
+          joinWithSeparator(
+              buildRoleString(format), buildResolutionString(format), buildBitrateString(format));
     } else if (trackType == C.TRACK_TYPE_AUDIO) {
       trackName =
           joinWithSeparator(
-              buildLabelString(format),
+              buildLanguageOrLabelString(format),
               buildAudioChannelString(format),
               buildBitrateString(format));
     } else {
-      trackName = buildLabelString(format);
+      trackName = buildLanguageOrLabelString(format);
     }
     return trackName.length() == 0 ? resources.getString(R.string.exo_track_unknown) : trackName;
   }
@@ -87,22 +89,43 @@ public class DefaultTrackNameProvider implements TrackNameProvider {
     }
   }
 
+  private String buildLanguageOrLabelString(Format format) {
+    String languageAndRole =
+        joinWithSeparator(buildLanguageString(format), buildRoleString(format));
+    return TextUtils.isEmpty(languageAndRole) ? buildLabelString(format) : languageAndRole;
+  }
+
   private String buildLabelString(Format format) {
-    if (!TextUtils.isEmpty(format.label)) {
-      return format.label;
-    }
-    // Fall back to using the language.
-    String language = format.language;
-    return TextUtils.isEmpty(language) || C.LANGUAGE_UNDETERMINED.equals(language)
-        ? ""
-        : buildLanguageString(language);
+    return TextUtils.isEmpty(format.label) ? "" : format.label;
   }
 
-  private String buildLanguageString(String language) {
+  private String buildLanguageString(Format format) {
+    String language = format.language;
+    if (TextUtils.isEmpty(language) || C.LANGUAGE_UNDETERMINED.equals(language)) {
+      return "";
+    }
     Locale locale = Util.SDK_INT >= 21 ? Locale.forLanguageTag(language) : new Locale(language);
     return locale.getDisplayName();
   }
 
+  private String buildRoleString(Format format) {
+    String roles = "";
+    if ((format.roleFlags & C.ROLE_FLAG_ALTERNATE) != 0) {
+      roles = resources.getString(R.string.exo_track_role_alternate);
+    }
+    if ((format.roleFlags & C.ROLE_FLAG_SUPPLEMENTARY) != 0) {
+      roles = joinWithSeparator(roles, resources.getString(R.string.exo_track_role_supplementary));
+    }
+    if ((format.roleFlags & C.ROLE_FLAG_COMMENTARY) != 0) {
+      roles = joinWithSeparator(roles, resources.getString(R.string.exo_track_role_commentary));
+    }
+    if ((format.roleFlags & (C.ROLE_FLAG_CAPTION | C.ROLE_FLAG_DESCRIBES_MUSIC_AND_SOUND)) != 0) {
+      roles =
+          joinWithSeparator(roles, resources.getString(R.string.exo_track_role_closed_captions));
+    }
+    return roles;
+  }
+
   private String joinWithSeparator(String... items) {
     String itemList = "";
     for (String item : items) {

library/ui/src/main/res/values/strings.xml

@@ -76,6 +76,14 @@
   <string name="exo_track_surround_5_point_1">5.1 surround sound</string>
   <!-- Describes a 7.1 (https://en.wikipedia.org/wiki/7.1_surround_sound) audio track. [CHAR LIMIT=40] -->
   <string name="exo_track_surround_7_point_1">7.1 surround sound</string>
+  <!-- Describes an alternate track, e.g. a video recorded from a different viewpoint. [CHAR LIMIT=40] -->
+  <string name="exo_track_role_alternate">Alternate</string>
+  <!-- Describes a supplementary track. [CHAR LIMIT=40] -->
+  <string name="exo_track_role_supplementary">Supplementary</string>
+  <!-- Describes a track containing commentary. [CHAR LIMIT=40] -->
+  <string name="exo_track_role_commentary">Commentary</string>
+  <!-- Describes a track with closed captions. [CHAR LIMIT=40] -->
+  <string name="exo_track_role_closed_captions">CC</string>
   <!-- Describes the bitrate of a media track in Megabits (https://en.wikipedia.org/wiki/Megabit) per second. [CHAR LIMIT=20] -->
   <string name="exo_track_bitrate"><xliff:g id="bitrate" example="5.2">%1$.2f</xliff:g> Mbps</string>
   <!-- Defines a way of appending an item to a list of items. For example appending "banana" to "apple, pear" to get "apple, pear, banana". Note: the command separator will appear between all consecutive list items, so do not use an equivalent of 'and'. [CHAR LIMIT=40] -->