Add support for looping sequences in SequenceAssetLoader

PiperOrigin-RevId: 517418886

library/transformer/src/main/java/com/google/android/exoplayer2/transformer/AudioSamplePipeline.java

@@ -153,6 +153,9 @@ import org.checkerframework.dataflow.qual.Pure;
       @Nullable Format trackFormat,
       boolean isLast) {
     if (trackFormat == null) {
+      checkState(
+          durationUs != C.TIME_UNSET,
+          "Could not generate silent audio because duration is unknown.");
       silentAudioGenerator.addSilence(durationUs);
       if (isLast) {
         queueEndOfStreamAfterSilence = true;

library/transformer/src/main/java/com/google/android/exoplayer2/transformer/EditedMediaItemSequence.java

@@ -34,6 +34,8 @@ public final class EditedMediaItemSequence {
    */
   public final ImmutableList<EditedMediaItem> editedMediaItems;
 
+  /* package */ final boolean isLooping;
+
   /**
    * Creates an instance.
    *
@@ -42,5 +44,6 @@ public final class EditedMediaItemSequence {
   public EditedMediaItemSequence(List<EditedMediaItem> editedMediaItems) {
     checkArgument(!editedMediaItems.isEmpty());
     this.editedMediaItems = ImmutableList.copyOf(editedMediaItems);
+    isLooping = false;
   }
 }