Pass MuxerWrapper to the TransformerInternal

For pause/resume feature, same MuxerWrapper needs to be
used across intermediate exports. So pass the MuxerWrapper
from Transformer.java
More specifically, when resume() is called
1. Create a MuxerWrapper and remux the previous
video samples (Export 1).
2. User the same MuxerWrapper and start processing
remaining video samples (Export 2).

PiperOrigin-RevId: 561325867

libraries/transformer/src/main/java/androidx/media3/transformer/MuxerWrapper.java

@@ -71,7 +71,6 @@ import org.checkerframework.checker.nullness.qual.RequiresNonNull;
 
   private final String outputPath;
   private final Muxer.Factory muxerFactory;
-  private final Listener listener;
   private final SparseArray<TrackInfo> trackTypeToInfo;
   private final ScheduledExecutorService abortScheduledExecutorService;
 
@@ -80,6 +79,7 @@ import org.checkerframework.checker.nullness.qual.RequiresNonNull;
   private @C.TrackType int previousTrackType;
   private long minTrackTimeUs;
   private long maxEndedTrackTimeUs;
+  private @MonotonicNonNull Listener listener;
   private @MonotonicNonNull ScheduledFuture<?> abortScheduledFuture;
   private boolean isAborted;
   private @MonotonicNonNull Muxer muxer;
@@ -87,16 +87,25 @@ import org.checkerframework.checker.nullness.qual.RequiresNonNull;
   private volatile int additionalRotationDegrees;
   private volatile int trackCount;
 
-  public MuxerWrapper(String outputPath, Muxer.Factory muxerFactory, Listener listener) {
+  /** Creates an instance. */
+  public MuxerWrapper(String outputPath, Muxer.Factory muxerFactory) {
     this.outputPath = outputPath;
     this.muxerFactory = muxerFactory;
-    this.listener = listener;
 
     trackTypeToInfo = new SparseArray<>();
     previousTrackType = C.TRACK_TYPE_NONE;
     abortScheduledExecutorService = Util.newSingleThreadScheduledExecutor(TIMER_THREAD_NAME);
   }
 
+  /**
+   * Sets a {@link MuxerWrapper.Listener}.
+   *
+   * <p>The {@link MuxerWrapper.Listener} must be set before calling any other methods.
+   */
+  public void setListener(Listener listener) {
+    this.listener = listener;
+  }
+
   /**
    * Sets the clockwise rotation to add to the {@linkplain #addTrackFormat(Format) video track's}
    * rotation, in degrees.
@@ -266,9 +275,9 @@ import org.checkerframework.checker.nullness.qual.RequiresNonNull;
 
     TrackInfo trackInfo = trackTypeToInfo.get(trackType);
     maxEndedTrackTimeUs = max(maxEndedTrackTimeUs, trackInfo.timeUs);
+    Listener listener = checkNotNull(this.listener);
     listener.onTrackEnded(
         trackType, trackInfo.format, trackInfo.getAverageBitrate(), trackInfo.sampleCount);
-
     if (trackType == C.TRACK_TYPE_VIDEO) {
       DebugTraceUtil.logEvent(DebugTraceUtil.EVENT_MUXER_TRACK_ENDED_VIDEO, trackInfo.timeUs);
     } else if (trackType == C.TRACK_TYPE_AUDIO) {
@@ -345,14 +354,15 @@ import org.checkerframework.checker.nullness.qual.RequiresNonNull;
                 return;
               }
               isAborted = true;
-              listener.onError(
+              checkNotNull(listener)
-                  ExportException.createForMuxer(
+                  .onError(
-                      new IllegalStateException(
+                      ExportException.createForMuxer(
-                          Util.formatInvariant(
+                          new IllegalStateException(
-                              MUXER_TIMEOUT_ERROR_FORMAT_STRING,
+                              Util.formatInvariant(
-                              maxDelayBetweenSamplesMs,
+                                  MUXER_TIMEOUT_ERROR_FORMAT_STRING,
-                              DebugTraceUtil.generateTraceSummary())),
+                                  maxDelayBetweenSamplesMs,
-                      ExportException.ERROR_CODE_MUXING_TIMEOUT));
+                                  DebugTraceUtil.generateTraceSummary())),
+                          ExportException.ERROR_CODE_MUXING_TIMEOUT));
             },
             maxDelayBetweenSamplesMs,
             MILLISECONDS);

libraries/transformer/src/main/java/androidx/media3/transformer/Transformer.java

@@ -837,6 +837,7 @@ public final class Transformer {
     verifyApplicationThread();
     checkState(transformerInternal == null, "There is already an export in progress.");
 
+    MuxerWrapper muxerWrapper = new MuxerWrapper(path, muxerFactory);
     TransformerInternalListener transformerInternalListener =
         new TransformerInternalListener(composition);
     HandlerWrapper applicationHandler = clock.createHandler(looper, /* callback= */ null);
@@ -862,13 +863,12 @@ public final class Transformer {
         new TransformerInternal(
             context,
             composition,
-            path,
             transformationRequest,
             assetLoaderFactory,
             audioMixerFactory,
             videoFrameProcessorFactory,
             encoderFactory,
-            muxerFactory,
+            muxerWrapper,
             transformerInternalListener,
             fallbackListener,
             applicationHandler,

libraries/transformer/src/main/java/androidx/media3/transformer/TransformerInternal.java

@@ -128,17 +128,16 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
   private volatile boolean released;
 
   // Warning suppression is needed to assign the MuxerWrapper with "this" as listener.
-  @SuppressWarnings("assignment.type.incompatible")
+  @SuppressWarnings({"argument.type.incompatible"})
   public TransformerInternal(
       Context context,
       Composition composition,
-      String outputPath,
       TransformationRequest transformationRequest,
       AssetLoader.Factory assetLoaderFactory,
       AudioMixer.Factory audioMixerFactory,
       VideoFrameProcessor.Factory videoFrameProcessorFactory,
       Codec.EncoderFactory encoderFactory,
-      Muxer.Factory muxerFactory,
+      MuxerWrapper muxerWrapper,
       Listener listener,
       FallbackListener fallbackListener,
       HandlerWrapper applicationHandler,
@@ -150,6 +149,9 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
     this.listener = listener;
     this.applicationHandler = applicationHandler;
     this.clock = clock;
+    this.muxerWrapper = muxerWrapper;
+    // It's safe to use "this" because we don't mux any data before exiting the constructor.
+    this.muxerWrapper.setListener(this);
     internalHandlerThread = new HandlerThread("Transformer:Internal");
     internalHandlerThread.start();
     sequenceAssetLoaders = new ArrayList<>();
@@ -192,10 +194,6 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
     HandlerWrapper internalHandler =
         clock.createHandler(internalLooper, /* callback= */ this::handleMessage);
     this.internalHandler = internalHandler;
-    // It's safe to use "this" because we don't mux any data before exiting the constructor.
-    @SuppressWarnings("nullness:argument.type.incompatible")
-    MuxerWrapper muxerWrapper = new MuxerWrapper(outputPath, muxerFactory, /* listener= */ this);
-    this.muxerWrapper = muxerWrapper;
   }
 
   public void start() {