Add DASH support for parsing standalone TTML files during extraction

This change applies to standalone TTML files linked directly from the manifest.

As a result, we no longer have the flakiness in the DashPlaybackTest which uses sidecar-loaded (standalone file) TTML subtitles. We experimentally opt into parsing subtitles during extraction and use SubtitleExtractor in hybrid mode.

PiperOrigin-RevId: 577457256

RELEASENOTES.md

@@ -38,6 +38,9 @@
 *   RTMP Extension:
 *   HLS Extension:
 *   DASH Extension:
+    *   Extend experimental support for parsing subtitles during extraction to
+        work with standalone TTML files (previously it only worked with
+        subtitles muxed into MP4 segments).
 *   Smooth Streaming Extension:
 *   RTSP Extension:
 *   Decoder Extensions (FFmpeg, VP9, AV1, MIDI, etc.):

libraries/common/src/main/java/androidx/media3/common/MimeTypes.java

@@ -25,6 +25,7 @@ import com.google.common.base.Ascii;
 import java.util.ArrayList;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
+import org.checkerframework.dataflow.qual.Pure;
 
 /** Defines common MIME types and helper methods. */
 public final class MimeTypes {
@@ -218,6 +219,7 @@ public final class MimeTypes {
    * "application" as their base type.
    */
   @UnstableApi
+  @Pure
   public static boolean isText(@Nullable String mimeType) {
     return BASE_TYPE_TEXT.equals(getTopLevelType(mimeType))
         || APPLICATION_MEDIA3_CUES.equals(mimeType)

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/source/chunk/BundledChunkExtractor.java

@@ -37,6 +37,7 @@ import androidx.media3.extractor.SeekMap;
 import androidx.media3.extractor.TrackOutput;
 import androidx.media3.extractor.mkv.MatroskaExtractor;
 import androidx.media3.extractor.mp4.FragmentedMp4Extractor;
+import androidx.media3.extractor.text.SubtitleExtractor;
 import androidx.media3.extractor.text.SubtitleParser;
 import androidx.media3.extractor.text.SubtitleTranscodingExtractor;
 import java.io.IOException;
@@ -86,8 +87,14 @@ public final class BundledChunkExtractor implements ExtractorOutput, ChunkExtrac
       @Nullable String containerMimeType = representationFormat.containerMimeType;
       Extractor extractor;
       if (MimeTypes.isText(containerMimeType)) {
-        // Text types do not need an extractor.
-        return null;
+        if (subtitleParserFactory == null) {
+          // Subtitles will be parsed after decoding
+          return null;
+        } else {
+          extractor =
+              new SubtitleExtractor(
+                  subtitleParserFactory.create(representationFormat), representationFormat);
+        }
       } else if (MimeTypes.isMatroska(containerMimeType)) {
         extractor = new MatroskaExtractor(MatroskaExtractor.FLAG_DISABLE_SEEK_FOR_CUES);
       } else {
@@ -103,7 +110,7 @@ public final class BundledChunkExtractor implements ExtractorOutput, ChunkExtrac
                 closedCaptionFormats,
                 playerEmsgTrackOutput);
       }
-      if (subtitleParserFactory != null) {
+      if (subtitleParserFactory != null && !MimeTypes.isText(containerMimeType)) {
         extractor = new SubtitleTranscodingExtractor(extractor, subtitleParserFactory);
       }
       return new BundledChunkExtractor(extractor, primaryTrackType, representationFormat);

libraries/exoplayer_dash/src/test/java/androidx/media3/exoplayer/dash/e2etest/DashPlaybackTest.java

@@ -38,7 +38,6 @@ import androidx.media3.test.utils.robolectric.ShadowMediaCodecConfig;
 import androidx.media3.test.utils.robolectric.TestPlayerRunHelper;
 import androidx.test.core.app.ApplicationProvider;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
-import org.junit.Ignore;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -52,8 +51,6 @@ public final class DashPlaybackTest {
       ShadowMediaCodecConfig.forAllSupportedMimeTypes();
 
   @Test
-  @Ignore(
-      "Disabled until subtitles are reliably asserted in robolectric tests [internal b/174661563].")
   public void ttmlStandaloneXmlFile() throws Exception {
     Context applicationContext = ApplicationProvider.getApplicationContext();
     CapturingRenderersFactory capturingRenderersFactory =
@@ -61,6 +58,9 @@ public final class DashPlaybackTest {
     ExoPlayer player =
         new ExoPlayer.Builder(applicationContext, capturingRenderersFactory)
             .setClock(new FakeClock(/* isAutoAdvancing= */ true))
+            .setMediaSourceFactory(
+                new DashMediaSource.Factory(new DefaultDataSource.Factory(applicationContext))
+                    .experimentalParseSubtitlesDuringExtraction(true))
             .build();
     player.setVideoSurface(new Surface(new SurfaceTexture(/* texName= */ 1)));
     PlaybackOutput playbackOutput = PlaybackOutput.register(player, capturingRenderersFactory);

libraries/extractor/src/main/java/androidx/media3/extractor/text/SubtitleExtractor.java

@@ -131,13 +131,13 @@ public class SubtitleExtractor implements Extractor {
   public void init(ExtractorOutput output) {
     checkState(state == STATE_CREATED);
     trackOutput = output.track(/* id= */ 0, C.TRACK_TYPE_TEXT);
+    trackOutput.format(format);
     output.endTracks();
     output.seekMap(
         new IndexSeekMap(
             /* positions= */ new long[] {0},
             /* timesUs= */ new long[] {0},
             /* durationUs= */ C.TIME_UNSET));
-    trackOutput.format(format);
     state = STATE_INITIALIZED;
   }