Add Extractor.getUnderlyingImplementation

This change uses this new method everywhere we currently `instanceof`
check an `Extractor` directly. This allows us to introduce
wrapping/delegating `Extractor` instances - because the `instanceof`
checks will continue to operate on the underlying instance.

HLS is a slightly different case, because it directly re-instantiates
`Extractor` instances, which is not compatible with an arbitrary
wrapping structure. Luckily the only `Extractor` instances that HLS
re-instantiates do not support muxed subtitles, so won't be wrapped
in the first place (although future changes might use the
delegating-`Extractor` pattern for other purposes, which might affect
HLS).

PiperOrigin-RevId: 542550928

RELEASENOTES.md

@@ -40,6 +40,10 @@
     *   Fix typo when determining `rotationDegrees`. Changed
         `projectionPosePitch` to `projectionPoseRoll`
         ([#461](https://github.com/androidx/media/pull/461)).
+    *   Remove the assumption that `Extractor` instances can be directly
+        inspected with `instanceof`. If you want runtime access to the
+        implementation details of an `Extractor` you must first call
+        `Extractor.getUnderlyingInstance`.
 *   Audio:
 *   Audio Offload:
     *   Add `AudioSink.getFormatOffloadSupport(Format)` that retrieves level of

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/source/BundledExtractorsAdapter.java

@@ -108,8 +108,12 @@ public final class BundledExtractorsAdapter implements ProgressiveMediaExtractor
 
   @Override
   public void disableSeekingOnMp3Streams() {
-    if (extractor instanceof Mp3Extractor) {
-      ((Mp3Extractor) extractor).disableSeeking();
+    if (extractor == null) {
+      return;
+    }
+    Extractor underlyingExtractor = extractor.getUnderlyingImplementation();
+    if (underlyingExtractor instanceof Mp3Extractor) {
+      ((Mp3Extractor) underlyingExtractor).disableSeeking();
     }
   }
 

libraries/exoplayer_hls/src/main/java/androidx/media3/exoplayer/hls/BundledHlsMediaChunkExtractor.java

@@ -15,9 +15,10 @@
  */
 package androidx.media3.exoplayer.hls;
 
+import static androidx.media3.common.util.Assertions.checkState;
+
 import androidx.annotation.VisibleForTesting;
 import androidx.media3.common.Format;
-import androidx.media3.common.util.Assertions;
 import androidx.media3.common.util.TimestampAdjuster;
 import androidx.media3.common.util.UnstableApi;
 import androidx.media3.extractor.Extractor;
@@ -71,20 +72,26 @@ public final class BundledHlsMediaChunkExtractor implements HlsMediaChunkExtract
 
   @Override
   public boolean isPackedAudioExtractor() {
-    return extractor instanceof AdtsExtractor
-        || extractor instanceof Ac3Extractor
-        || extractor instanceof Ac4Extractor
-        || extractor instanceof Mp3Extractor;
+    Extractor underlyingExtractor = extractor.getUnderlyingImplementation();
+    return underlyingExtractor instanceof AdtsExtractor
+        || underlyingExtractor instanceof Ac3Extractor
+        || underlyingExtractor instanceof Ac4Extractor
+        || underlyingExtractor instanceof Mp3Extractor;
   }
 
   @Override
   public boolean isReusable() {
-    return extractor instanceof TsExtractor || extractor instanceof FragmentedMp4Extractor;
+    Extractor underlyingExtractor = extractor.getUnderlyingImplementation();
+    return underlyingExtractor instanceof TsExtractor
+        || underlyingExtractor instanceof FragmentedMp4Extractor;
   }
 
   @Override
   public HlsMediaChunkExtractor recreate() {
-    Assertions.checkState(!isReusable());
+    checkState(!isReusable());
+    checkState(
+        extractor.getUnderlyingImplementation() == extractor,
+        "Can't recreate wrapped extractors. Outer type: " + extractor.getClass());
     Extractor newExtractorInstance;
     if (extractor instanceof WebvttExtractor) {
       newExtractorInstance =

libraries/extractor/src/main/java/androidx/media3/extractor/Extractor.java

@@ -120,4 +120,15 @@ public interface Extractor {
 
   /** Releases all kept resources. */
   void release();
+
+  /**
+   * Returns the 'real' {@code Extractor} implementation if this is a delegating instance, or {@code
+   * this} if this instance does the extraction directly without delegating (the default behaviour).
+   *
+   * <p>{@code Extractor} implementations that operate by delegating to another {@code Extractor}
+   * should override this method to return that delegate.
+   */
+  default Extractor getUnderlyingImplementation() {
+    return this;
+  }
 }