Ensure EOS is queued after processing generated silence with effects.

When generating silence for AudioProcessingPipeline, audio never
queued EOS downstream.

Linked to this, when silence followed an item with audio, the silence
was added to SilentAudioGenerator before the mediaItem reconfiguration
occurred. If the silence had effects, the APP would be flushed after
silence queued EOS, resetting APP.isEnded back to false, so AudioGraph
never ended.

Regression tests reproduce failure without fix, but pass with it.

PiperOrigin-RevId: 550853714

libraries/test_data/src/test/assets/transformerdumps/mp4/sample.mp4.silentaudio_48000hz.dump

@@ -0,0 +1,476 @@
+format 0:
+  id = 1
+  sampleMimeType = video/avc
+  codecs = avc1.64001F
+  maxInputSize = 36722
+  width = 1080
+  height = 720
+  frameRate = 29.970028
+  metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
+  initializationData:
+    data = length 29, hash 4746B5D9
+    data = length 10, hash 7A0D0F2B
+container metadata = entries=[TSSE: description=null: values=[Lavf56.1.0], xyz: latitude=40.68, longitude=-74.5, Mp4Timestamp: creation time=3547558895, modification time=3547558895, timescale=1000]
+format 1:
+  averageBitrate = 131072
+  sampleMimeType = audio/mp4a-latm
+  channelCount = 2
+  sampleRate = 48000
+  pcmEncoding = 2
+sample:
+  trackIndex = 0
+  dataHashCode = -770308242
+  size = 36692
+  isKeyFrame = true
+  presentationTimeUs = 0
+sample:
+  trackIndex = 0
+  dataHashCode = -732087136
+  size = 5312
+  isKeyFrame = false
+  presentationTimeUs = 66733
+sample:
+  trackIndex = 0
+  dataHashCode = 468156717
+  size = 599
+  isKeyFrame = false
+  presentationTimeUs = 33366
+sample:
+  trackIndex = 0
+  dataHashCode = 1150349584
+  size = 7735
+  isKeyFrame = false
+  presentationTimeUs = 200200
+sample:
+  trackIndex = 0
+  dataHashCode = 1443582006
+  size = 987
+  isKeyFrame = false
+  presentationTimeUs = 133466
+sample:
+  trackIndex = 0
+  dataHashCode = -310585145
+  size = 673
+  isKeyFrame = false
+  presentationTimeUs = 100100
+sample:
+  trackIndex = 0
+  dataHashCode = 807460688
+  size = 523
+  isKeyFrame = false
+  presentationTimeUs = 166833
+sample:
+  trackIndex = 0
+  dataHashCode = 1936487090
+  size = 6061
+  isKeyFrame = false
+  presentationTimeUs = 333666
+sample:
+  trackIndex = 0
+  dataHashCode = -32297181
+  size = 992
+  isKeyFrame = false
+  presentationTimeUs = 266933
+sample:
+  trackIndex = 0
+  dataHashCode = 1529616406
+  size = 623
+  isKeyFrame = false
+  presentationTimeUs = 233566
+sample:
+  trackIndex = 0
+  dataHashCode = 1949198785
+  size = 421
+  isKeyFrame = false
+  presentationTimeUs = 300300
+sample:
+  trackIndex = 0
+  dataHashCode = -147880287
+  size = 4899
+  isKeyFrame = false
+  presentationTimeUs = 433766
+sample:
+  trackIndex = 0
+  dataHashCode = 1369083472
+  size = 568
+  isKeyFrame = false
+  presentationTimeUs = 400400
+sample:
+  trackIndex = 0
+  dataHashCode = 965782073
+  size = 620
+  isKeyFrame = false
+  presentationTimeUs = 367033
+sample:
+  trackIndex = 0
+  dataHashCode = -261176150
+  size = 5450
+  isKeyFrame = false
+  presentationTimeUs = 567233
+sample:
+  trackIndex = 0
+  dataHashCode = -1830836678
+  size = 1051
+  isKeyFrame = false
+  presentationTimeUs = 500500
+sample:
+  trackIndex = 0
+  dataHashCode = 1767407540
+  size = 874
+  isKeyFrame = false
+  presentationTimeUs = 467133
+sample:
+  trackIndex = 0
+  dataHashCode = 918440283
+  size = 781
+  isKeyFrame = false
+  presentationTimeUs = 533866
+sample:
+  trackIndex = 0
+  dataHashCode = -1408463661
+  size = 4725
+  isKeyFrame = false
+  presentationTimeUs = 700700
+sample:
+  trackIndex = 0
+  dataHashCode = 1569455924
+  size = 1022
+  isKeyFrame = false
+  presentationTimeUs = 633966
+sample:
+  trackIndex = 0
+  dataHashCode = -1723778407
+  size = 790
+  isKeyFrame = false
+  presentationTimeUs = 600600
+sample:
+  trackIndex = 0
+  dataHashCode = 1578275472
+  size = 610
+  isKeyFrame = false
+  presentationTimeUs = 667333
+sample:
+  trackIndex = 0
+  dataHashCode = 1989768395
+  size = 2751
+  isKeyFrame = false
+  presentationTimeUs = 834166
+sample:
+  trackIndex = 0
+  dataHashCode = -1215674502
+  size = 745
+  isKeyFrame = false
+  presentationTimeUs = 767433
+sample:
+  trackIndex = 0
+  dataHashCode = -814473606
+  size = 621
+  isKeyFrame = false
+  presentationTimeUs = 734066
+sample:
+  trackIndex = 0
+  dataHashCode = 498370894
+  size = 505
+  isKeyFrame = false
+  presentationTimeUs = 800800
+sample:
+  trackIndex = 0
+  dataHashCode = -1051506468
+  size = 1268
+  isKeyFrame = false
+  presentationTimeUs = 967633
+sample:
+  trackIndex = 0
+  dataHashCode = -1025604144
+  size = 880
+  isKeyFrame = false
+  presentationTimeUs = 900900
+sample:
+  trackIndex = 0
+  dataHashCode = -913586520
+  size = 530
+  isKeyFrame = false
+  presentationTimeUs = 867533
+sample:
+  trackIndex = 0
+  dataHashCode = 1340459242
+  size = 568
+  isKeyFrame = false
+  presentationTimeUs = 934266
+sample:
+  trackIndex = 1
+  dataHashCode = 864256769
+  size = 4456
+  isKeyFrame = true
+  presentationTimeUs = 0
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 23208
+sample:
+  trackIndex = 1
+  dataHashCode = 864256769
+  size = 4456
+  isKeyFrame = true
+  presentationTimeUs = 46437
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 69645
+sample:
+  trackIndex = 1
+  dataHashCode = 864256769
+  size = 4456
+  isKeyFrame = true
+  presentationTimeUs = 92875
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 116083
+sample:
+  trackIndex = 1
+  dataHashCode = 864256769
+  size = 4456
+  isKeyFrame = true
+  presentationTimeUs = 139312
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 162520
+sample:
+  trackIndex = 1
+  dataHashCode = 864256769
+  size = 4456
+  isKeyFrame = true
+  presentationTimeUs = 185750
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 208958
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 232187
+sample:
+  trackIndex = 1
+  dataHashCode = 864256769
+  size = 4456
+  isKeyFrame = true
+  presentationTimeUs = 255416
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 278625
+sample:
+  trackIndex = 1
+  dataHashCode = 864256769
+  size = 4456
+  isKeyFrame = true
+  presentationTimeUs = 301854
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 325062
+sample:
+  trackIndex = 1
+  dataHashCode = 864256769
+  size = 4456
+  isKeyFrame = true
+  presentationTimeUs = 348291
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 371500
+sample:
+  trackIndex = 1
+  dataHashCode = 864256769
+  size = 4456
+  isKeyFrame = true
+  presentationTimeUs = 394729
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 417937
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 441166
+sample:
+  trackIndex = 1
+  dataHashCode = 864256769
+  size = 4456
+  isKeyFrame = true
+  presentationTimeUs = 464395
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 487604
+sample:
+  trackIndex = 1
+  dataHashCode = 864256769
+  size = 4456
+  isKeyFrame = true
+  presentationTimeUs = 510833
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 534041
+sample:
+  trackIndex = 1
+  dataHashCode = 864256769
+  size = 4456
+  isKeyFrame = true
+  presentationTimeUs = 557270
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 580479
+sample:
+  trackIndex = 1
+  dataHashCode = 864256769
+  size = 4456
+  isKeyFrame = true
+  presentationTimeUs = 603708
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 626916
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 650145
+sample:
+  trackIndex = 1
+  dataHashCode = 864256769
+  size = 4456
+  isKeyFrame = true
+  presentationTimeUs = 673375
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 696583
+sample:
+  trackIndex = 1
+  dataHashCode = 864256769
+  size = 4456
+  isKeyFrame = true
+  presentationTimeUs = 719812
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 743020
+sample:
+  trackIndex = 1
+  dataHashCode = 864256769
+  size = 4456
+  isKeyFrame = true
+  presentationTimeUs = 766250
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 789458
+sample:
+  trackIndex = 1
+  dataHashCode = 864256769
+  size = 4456
+  isKeyFrame = true
+  presentationTimeUs = 812687
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 835895
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 859125
+sample:
+  trackIndex = 1
+  dataHashCode = 864256769
+  size = 4456
+  isKeyFrame = true
+  presentationTimeUs = 882354
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 905562
+sample:
+  trackIndex = 1
+  dataHashCode = 864256769
+  size = 4456
+  isKeyFrame = true
+  presentationTimeUs = 928791
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 952000
+sample:
+  trackIndex = 1
+  dataHashCode = 864256769
+  size = 4456
+  isKeyFrame = true
+  presentationTimeUs = 975229
+sample:
+  trackIndex = 1
+  dataHashCode = -266855807
+  size = 4460
+  isKeyFrame = true
+  presentationTimeUs = 998437
+sample:
+  trackIndex = 1
+  dataHashCode = -115707775
+  size = 444
+  isKeyFrame = true
+  presentationTimeUs = 1021666
+sample:
+  trackIndex = 1
+  dataHashCode = 923521
+  size = 4
+  isKeyFrame = true
+  presentationTimeUs = 1023979
+released = true

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

@@ -23,7 +23,6 @@ import static androidx.media3.common.util.Assertions.checkState;
 import static androidx.media3.common.util.Assertions.checkStateNotNull;
 import static androidx.media3.decoder.DecoderInputBuffer.BUFFER_REPLACEMENT_MODE_DIRECT;
 
-import android.util.Pair;
 import androidx.annotation.Nullable;
 import androidx.media3.common.C;
 import androidx.media3.common.Format;
@@ -52,14 +51,13 @@ import java.util.concurrent.atomic.AtomicReference;
   private final SilentAudioGenerator silentAudioGenerator;
   private final Queue<DecoderInputBuffer> availableInputBuffers;
   private final Queue<DecoderInputBuffer> pendingInputBuffers;
-  private final AtomicReference<@NullableType Pair<EditedMediaItem, @NullableType Format>>
-      pendingMediaItem;
+  private final AtomicReference<@NullableType MediaItemChange> pendingMediaItemChange;
 
   @Nullable private DecoderInputBuffer currentInputBufferBeingOutput;
   private AudioProcessingPipeline audioProcessingPipeline;
-  private boolean receivedFirstMediaItemCallback;
+  private boolean processedFirstMediaItemChange;
   private boolean receivedEndOfStreamFromInput;
-  private volatile boolean queueEndOfStreamAfterSilence;
+  private boolean queueEndOfStreamAfterSilence;
 
   // TODO(b/260618558): Move silent audio generation upstream of this component.
   public AudioGraph(Format firstInputFormat, EditedMediaItem firstEditedMediaItem)
@@ -73,7 +71,7 @@ import java.util.concurrent.atomic.AtomicReference;
       availableInputBuffers.add(inputBuffer);
     }
     pendingInputBuffers = new ConcurrentLinkedDeque<>();
-    pendingMediaItem = new AtomicReference<>();
+    pendingMediaItemChange = new AtomicReference<>();
     AudioFormat inputAudioFormat = new AudioFormat(firstInputFormat);
     silentAudioGenerator = new SilentAudioGenerator(inputAudioFormat);
     audioProcessingPipeline =
@@ -82,6 +80,8 @@ import java.util.concurrent.atomic.AtomicReference;
             /* trackFormat= */ firstInputFormat,
             /* inputAudioFormat= */ inputAudioFormat,
             /* requiredOutputAudioFormat= */ AudioFormat.NOT_SET);
+    // APP configuration not active until flush called. getOutputAudioFormat based on active config.
+    audioProcessingPipeline.flush();
     outputAudioFormat = audioProcessingPipeline.getOutputAudioFormat();
   }
 
@@ -102,9 +102,9 @@ import java.util.concurrent.atomic.AtomicReference;
       return outputBuffer;
     }
 
-    if (!hasDataToOutput() && pendingMediaItem.get() != null) {
+    if (!hasDataToOutput() && pendingMediaItemChange.get() != null) {
       try {
-        reconfigureProcessingForPendingMediaItem();
+        configureForPendingMediaItemChange();
       } catch (AudioProcessor.UnhandledAudioFormatException e) {
         throw ExportException.createForAudioProcessing(e, "AudioGraph reconfiguration");
       }
@@ -123,26 +123,18 @@ import java.util.concurrent.atomic.AtomicReference;
       checkState(
           durationUs != C.TIME_UNSET,
           "Could not generate silent audio because duration is unknown.");
-      silentAudioGenerator.addSilence(durationUs);
-      if (isLast) {
-        queueEndOfStreamAfterSilence = true;
-      }
     } else {
       checkState(MimeTypes.isAudio(trackFormat.sampleMimeType));
       checkState(trackFormat.pcmEncoding != Format.NO_VALUE);
     }
-
-    if (!receivedFirstMediaItemCallback) {
-      receivedFirstMediaItemCallback = true;
-      return;
-    }
-    pendingMediaItem.set(Pair.create(editedMediaItem, trackFormat));
+    pendingMediaItemChange.set(
+        new MediaItemChange(editedMediaItem, durationUs, trackFormat, isLast));
   }
 
   @Override
   @Nullable
   public DecoderInputBuffer getInputBuffer() {
-    if (shouldGenerateSilence() || pendingMediaItem.get() != null) {
+    if (silentAudioGenerator.hasRemaining() || pendingMediaItemChange.get() != null) {
       return null;
     }
     return availableInputBuffers.peek();
@@ -150,7 +142,7 @@ import java.util.concurrent.atomic.AtomicReference;
 
   @Override
   public boolean queueInputBuffer() {
-    checkState(pendingMediaItem.get() == null);
+    checkState(pendingMediaItemChange.get() == null);
     DecoderInputBuffer inputBuffer = availableInputBuffers.remove();
     pendingInputBuffers.add(inputBuffer);
     return true;
@@ -165,15 +157,17 @@ import java.util.concurrent.atomic.AtomicReference;
     if (hasDataToOutput()) {
       return false;
     }
-    if (pendingMediaItem.get() != null) {
+    if (pendingMediaItemChange.get() != null) {
       return false;
     }
-    // Only read volatile variable queueEndOfStreamAfterSilence if there is a chance that the
-    // graph has ended.
     return receivedEndOfStreamFromInput || queueEndOfStreamAfterSilence;
   }
 
   private ByteBuffer getOutputInternal() {
+    if (!processedFirstMediaItemChange) {
+      return EMPTY_BUFFER;
+    }
+
     if (!audioProcessingPipeline.isOperational()) {
       return feedOutputFromInput();
     }
@@ -183,22 +177,23 @@ import java.util.concurrent.atomic.AtomicReference;
     return audioProcessingPipeline.getOutput();
   }
 
-  /**
-   * Attempts to feed input data to the {@link AudioProcessingPipeline}.
-   *
-   * @return Whether it may be possible to process more data immediately by calling this method
-   *     again.
-   */
   private boolean feedProcessingPipelineFromInput() {
-    if (shouldGenerateSilence()) {
+    if (silentAudioGenerator.hasRemaining()) {
       ByteBuffer inputData = silentAudioGenerator.getBuffer();
       audioProcessingPipeline.queueInput(inputData);
-      return !inputData.hasRemaining();
+      if (inputData.hasRemaining()) {
+        return false;
+      }
+      if (!silentAudioGenerator.hasRemaining()) {
+        audioProcessingPipeline.queueEndOfStream();
+        return false;
+      }
+      return true;
     }
 
     @Nullable DecoderInputBuffer pendingInputBuffer = pendingInputBuffers.peek();
     if (pendingInputBuffer == null) {
-      if (pendingMediaItem.get() != null) {
+      if (pendingMediaItemChange.get() != null) {
         audioProcessingPipeline.queueEndOfStream();
       }
       return false;
@@ -214,16 +209,14 @@ import java.util.concurrent.atomic.AtomicReference;
     ByteBuffer inputData = checkNotNull(pendingInputBuffer.data);
     audioProcessingPipeline.queueInput(inputData);
     if (inputData.hasRemaining()) {
-      // APP could not consume all input.
       return false;
     }
-    // All input consumed, remove from pending and make available.
     clearAndAddToAvailableBuffers(pendingInputBuffers.remove());
     return true;
   }
 
   private ByteBuffer feedOutputFromInput() {
-    if (shouldGenerateSilence()) {
+    if (silentAudioGenerator.hasRemaining()) {
       return silentAudioGenerator.getBuffer();
     }
 
@@ -262,6 +255,10 @@ import java.util.concurrent.atomic.AtomicReference;
   }
 
   private boolean hasDataToOutput() {
+    if (!processedFirstMediaItemChange) {
+      return false;
+    }
+
     if (currentInputBufferBeingOutput != null
         && currentInputBufferBeingOutput.data != null
         && currentInputBufferBeingOutput.data.hasRemaining()) {
@@ -279,10 +276,6 @@ import java.util.concurrent.atomic.AtomicReference;
     return false;
   }
 
-  private boolean shouldGenerateSilence() {
-    return silentAudioGenerator.hasRemaining() && pendingInputBuffers.isEmpty();
-  }
-
   private void clearAndAddToAvailableBuffers(DecoderInputBuffer inputBuffer) {
     inputBuffer.clear();
     inputBuffer.timeUs = 0;
@@ -290,28 +283,38 @@ import java.util.concurrent.atomic.AtomicReference;
   }
 
   /**
-   * Reconfigures audio processing based on the pending {@linkplain #onMediaItemChanged media item
-   * change}.
+   * Configures the graph based on the pending {@linkplain #onMediaItemChanged media item change}.
    *
-   * <p>Before reconfiguration, all {@linkplain #hasDataToOutput() pending data} must be consumed
+   * <p>Before configuration, all {@linkplain #hasDataToOutput() pending data} must be consumed
    * through {@link #getOutput()}.
    */
-  private void reconfigureProcessingForPendingMediaItem() throws UnhandledAudioFormatException {
-    checkState(!hasDataToOutput());
-    Pair<EditedMediaItem, @NullableType Format> pendingChange =
-        checkStateNotNull(pendingMediaItem.get());
-    AudioFormat pendingAudioFormat =
-        pendingChange.second != null
-            ? new AudioFormat(pendingChange.second)
-            : silentAudioGenerator.audioFormat;
-    audioProcessingPipeline =
-        configureProcessing(
-            /* editedMediaItem= */ pendingChange.first,
-            /* trackFormat= */ pendingChange.second,
-            /* inputAudioFormat= */ pendingAudioFormat,
-            /* requiredOutputAudioFormat= */ outputAudioFormat);
-    pendingMediaItem.set(null);
+  private void configureForPendingMediaItemChange() throws UnhandledAudioFormatException {
+    MediaItemChange pendingChange = checkStateNotNull(pendingMediaItemChange.get());
+
+    AudioFormat pendingAudioFormat;
+    if (pendingChange.format != null) {
+      pendingAudioFormat = new AudioFormat(pendingChange.format);
+    } else { // Generating silence
+      pendingAudioFormat = silentAudioGenerator.audioFormat;
+      silentAudioGenerator.addSilence(pendingChange.durationUs);
+      if (pendingChange.isLast) {
+        queueEndOfStreamAfterSilence = true;
+      }
+    }
+
+    if (processedFirstMediaItemChange) {
+      // APP is configured in constructor for first media item.
+      audioProcessingPipeline =
+          configureProcessing(
+              /* editedMediaItem= */ pendingChange.editedMediaItem,
+              /* trackFormat= */ pendingChange.format,
+              /* inputAudioFormat= */ pendingAudioFormat,
+              /* requiredOutputAudioFormat= */ outputAudioFormat);
+    }
+    audioProcessingPipeline.flush();
+    pendingMediaItemChange.set(null);
     receivedEndOfStreamFromInput = false;
+    processedFirstMediaItemChange = true;
   }
 
   private static AudioProcessingPipeline configureProcessing(
@@ -357,7 +360,21 @@ import java.util.concurrent.atomic.AtomicReference;
           "Audio format can not be modified to match existing downstream format", inputAudioFormat);
     }
 
-    audioProcessingPipeline.flush();
     return audioProcessingPipeline;
   }
+
+  private static final class MediaItemChange {
+    public final EditedMediaItem editedMediaItem;
+    public final long durationUs;
+    @Nullable public final Format format;
+    public final boolean isLast;
+
+    public MediaItemChange(
+        EditedMediaItem editedMediaItem, long durationUs, @Nullable Format format, boolean isLast) {
+      this.editedMediaItem = editedMediaItem;
+      this.durationUs = durationUs;
+      this.format = format;
+      this.isLast = isLast;
+    }
+  }
 }

libraries/transformer/src/test/java/androidx/media3/transformer/MediaItemExportTest.java

@@ -353,6 +353,34 @@ public final class MediaItemExportTest {
         getDumpFileName(FILE_AUDIO_VIDEO + ".silentaudio"));
   }
 
+  @Test
+  public void start_forceAudioTrackAndRemoveAudioWithEffects_generatesSilentAudio()
+      throws Exception {
+    Transformer transformer =
+        createTransformerBuilder(testMuxerHolder, /* enableFallback= */ false).build();
+    SonicAudioProcessor sonicAudioProcessor = new SonicAudioProcessor();
+    sonicAudioProcessor.setOutputSampleRateHz(48000);
+    EditedMediaItem editedMediaItem =
+        new EditedMediaItem.Builder(MediaItem.fromUri(ASSET_URI_PREFIX + FILE_AUDIO_VIDEO))
+            .setRemoveAudio(true)
+            .setEffects(new Effects(ImmutableList.of(sonicAudioProcessor), ImmutableList.of()))
+            .build();
+    EditedMediaItemSequence sequence =
+        new EditedMediaItemSequence(ImmutableList.of(editedMediaItem));
+    Composition composition =
+        new Composition.Builder(ImmutableList.of(sequence))
+            .experimentalSetForceAudioTrack(true)
+            .build();
+
+    transformer.start(composition, outputPath);
+    TransformerTestRunner.runLooper(transformer);
+
+    DumpFileAsserts.assertOutput(
+        context,
+        checkNotNull(testMuxerHolder.testMuxer),
+        getDumpFileName(FILE_AUDIO_VIDEO + ".silentaudio_48000hz"));
+  }
+
   @Test
   public void start_forceAudioTrackAndRemoveVideo_isIgnored() throws Exception {
     Transformer transformer =

libraries/transformer/src/test/java/androidx/media3/transformer/SequenceExportTest.java

@@ -177,7 +177,33 @@ public final class SequenceExportTest {
   }
 
   @Test
-  public void start_concatenateSilenceAndAudioWithTransmuxVideo_completesSuccessfully()
+  public void concatenateAudioAndSilence_withTransmuxVideo_completesSuccessfully()
+      throws Exception {
+    Transformer transformer =
+        createTransformerBuilder(testMuxerHolder, /* enableFallback= */ false).build();
+    MediaItem mediaItem = MediaItem.fromUri(ASSET_URI_PREFIX + FILE_AUDIO_RAW_VIDEO);
+    EditedMediaItem audioVideoMediaItem = new EditedMediaItem.Builder(mediaItem).build();
+    EditedMediaItem videoOnlyMediaItem =
+        new EditedMediaItem.Builder(mediaItem).setRemoveAudio(true).build();
+    EditedMediaItemSequence sequence =
+        new EditedMediaItemSequence(ImmutableList.of(audioVideoMediaItem, videoOnlyMediaItem));
+    Composition composition =
+        new Composition.Builder(ImmutableList.of(sequence))
+            .experimentalSetForceAudioTrack(true)
+            .setTransmuxVideo(true)
+            .build();
+
+    transformer.start(composition, outputPath);
+    TransformerTestRunner.runLooper(transformer);
+
+    DumpFileAsserts.assertOutput(
+        context,
+        checkNotNull(testMuxerHolder.testMuxer),
+        getDumpFileName(FILE_AUDIO_RAW_VIDEO + ".audio_then_silence"));
+  }
+
+  @Test
+  public void concatenateSilenceAndAudio_withTransmuxVideo_completesSuccessfully()
       throws Exception {
     Transformer transformer =
         createTransformerBuilder(testMuxerHolder, /* enableFallback= */ false).build();
@@ -203,20 +229,28 @@ public final class SequenceExportTest {
   }
 
   @Test
-  public void start_concatenateSilenceAndAudioWithEffectsAndTransmuxVideo_completesSuccessfully()
+  public void concatenateAudioAndSilence_withEffectsAndTransmuxVideo_completesSuccessfully()
       throws Exception {
     Transformer transformer =
         createTransformerBuilder(testMuxerHolder, /* enableFallback= */ false).build();
     MediaItem mediaItem = MediaItem.fromUri(ASSET_URI_PREFIX + FILE_AUDIO_RAW_VIDEO);
-    SonicAudioProcessor sonicAudioProcessor = createPitchChangingAudioProcessor(/* pitch= */ 2f);
-    Effects effects =
-        new Effects(ImmutableList.of(sonicAudioProcessor), /* videoEffects= */ ImmutableList.of());
-    EditedMediaItem noAudioEditedMediaItem =
-        new EditedMediaItem.Builder(mediaItem).setRemoveAudio(true).setEffects(effects).build();
     EditedMediaItem audioEditedMediaItem =
-        new EditedMediaItem.Builder(mediaItem).setEffects(effects).build();
+        new EditedMediaItem.Builder(mediaItem)
+            .setEffects(
+                new Effects(
+                    ImmutableList.of(createPitchChangingAudioProcessor(/* pitch= */ 2f)),
+                    /* videoEffects= */ ImmutableList.of()))
+            .build();
+    EditedMediaItem noAudioEditedMediaItem =
+        new EditedMediaItem.Builder(mediaItem)
+            .setRemoveAudio(true)
+            .setEffects(
+                new Effects(
+                    ImmutableList.of(createPitchChangingAudioProcessor(/* pitch= */ 2f)),
+                    /* videoEffects= */ ImmutableList.of()))
+            .build();
     EditedMediaItemSequence sequence =
-        new EditedMediaItemSequence(ImmutableList.of(noAudioEditedMediaItem, audioEditedMediaItem));
+        new EditedMediaItemSequence(ImmutableList.of(audioEditedMediaItem, noAudioEditedMediaItem));
     Composition composition =
         new Composition.Builder(ImmutableList.of(sequence))
             .experimentalSetForceAudioTrack(true)
@@ -226,12 +260,193 @@ public final class SequenceExportTest {
     transformer.start(composition, outputPath);
     TransformerTestRunner.runLooper(transformer);
 
+    DumpFileAsserts.assertOutput(
+        context,
+        checkNotNull(testMuxerHolder.testMuxer),
+        getDumpFileName(FILE_AUDIO_RAW_VIDEO + ".audio_then_silence_with_effects"));
+  }
+
+  @Test
+  public void concatenateSilenceAndAudio_withEffectsAndTransmuxVideo_completesSuccessfully()
+      throws Exception {
+    Transformer transformer =
+        createTransformerBuilder(testMuxerHolder, /* enableFallback= */ false).build();
+    MediaItem mediaItem = MediaItem.fromUri(ASSET_URI_PREFIX + FILE_AUDIO_RAW_VIDEO);
+    EditedMediaItem noAudioEditedMediaItem =
+        new EditedMediaItem.Builder(mediaItem)
+            .setRemoveAudio(true)
+            .setEffects(
+                new Effects(
+                    ImmutableList.of(createPitchChangingAudioProcessor(/* pitch= */ 2f)),
+                    /* videoEffects= */ ImmutableList.of()))
+            .build();
+    EditedMediaItem audioEditedMediaItem =
+        new EditedMediaItem.Builder(mediaItem)
+            .setEffects(
+                new Effects(
+                    ImmutableList.of(createPitchChangingAudioProcessor(/* pitch= */ 2f)),
+                    /* videoEffects= */ ImmutableList.of()))
+            .build();
+    Composition composition =
+        new Composition.Builder(
+                ImmutableList.of(
+                    new EditedMediaItemSequence(
+                        ImmutableList.of(noAudioEditedMediaItem, audioEditedMediaItem))))
+            .experimentalSetForceAudioTrack(true)
+            .setTransmuxVideo(true)
+            .build();
+
+    transformer.start(composition, outputPath);
+    TransformerTestRunner.runLooper(transformer);
+
     DumpFileAsserts.assertOutput(
         context,
         checkNotNull(testMuxerHolder.testMuxer),
         getDumpFileName(FILE_AUDIO_RAW_VIDEO + ".silence_then_audio_with_effects"));
   }
 
+  @Test
+  public void concatenateSilenceAndSilence_withTransmuxVideo_completesSuccessfully()
+      throws Exception {
+    Transformer transformer =
+        createTransformerBuilder(testMuxerHolder, /* enableFallback= */ false).build();
+    MediaItem mediaItem = MediaItem.fromUri(ASSET_URI_PREFIX + FILE_AUDIO_RAW_VIDEO);
+    EditedMediaItem videoOnlyMediaItem =
+        new EditedMediaItem.Builder(mediaItem).setRemoveAudio(true).build();
+    EditedMediaItemSequence sequence =
+        new EditedMediaItemSequence(ImmutableList.of(videoOnlyMediaItem, videoOnlyMediaItem));
+    Composition composition =
+        new Composition.Builder(ImmutableList.of(sequence))
+            .experimentalSetForceAudioTrack(true)
+            .setTransmuxVideo(true)
+            .build();
+
+    transformer.start(composition, outputPath);
+    TransformerTestRunner.runLooper(transformer);
+
+    DumpFileAsserts.assertOutput(
+        context,
+        checkNotNull(testMuxerHolder.testMuxer),
+        getDumpFileName(FILE_AUDIO_RAW_VIDEO + ".silence_then_silence"));
+  }
+
+  @Test
+  public void concatenateEditedSilenceAndSilence_withTransmuxVideo_completesSuccessfully()
+      throws Exception {
+    Transformer transformer =
+        createTransformerBuilder(testMuxerHolder, /* enableFallback= */ false).build();
+    MediaItem mediaItem = MediaItem.fromUri(ASSET_URI_PREFIX + FILE_AUDIO_RAW_VIDEO);
+    EditedMediaItem silenceWithEffectsItem =
+        new EditedMediaItem.Builder(mediaItem)
+            .setRemoveAudio(true)
+            .setEffects(
+                new Effects(
+                    ImmutableList.of(createPitchChangingAudioProcessor(/* pitch= */ 2f)),
+                    /* videoEffects= */ ImmutableList.of()))
+            .build();
+    EditedMediaItem silenceItem =
+        new EditedMediaItem.Builder(mediaItem)
+            .setRemoveAudio(true)
+            .setEffects(
+                new Effects(
+                    ImmutableList.of(createPitchChangingAudioProcessor(/* pitch= */ 2f)),
+                    /* videoEffects= */ ImmutableList.of()))
+            .build();
+    EditedMediaItemSequence sequence =
+        new EditedMediaItemSequence(ImmutableList.of(silenceWithEffectsItem, silenceItem));
+    Composition composition =
+        new Composition.Builder(ImmutableList.of(sequence))
+            .experimentalSetForceAudioTrack(true)
+            .setTransmuxVideo(true)
+            .build();
+
+    transformer.start(composition, outputPath);
+    TransformerTestRunner.runLooper(transformer);
+
+    DumpFileAsserts.assertOutput(
+        context,
+        checkNotNull(testMuxerHolder.testMuxer),
+        getDumpFileName(FILE_AUDIO_RAW_VIDEO + ".silence-effects_then_silence"));
+  }
+
+  @Test
+  public void concatenateSilenceAndEditedSilence_withTransmuxVideo_completesSuccessfully()
+      throws Exception {
+    Transformer transformer =
+        createTransformerBuilder(testMuxerHolder, /* enableFallback= */ false).build();
+    MediaItem mediaItem = MediaItem.fromUri(ASSET_URI_PREFIX + FILE_AUDIO_RAW_VIDEO);
+    EditedMediaItem silenceWithEffectsItem =
+        new EditedMediaItem.Builder(mediaItem)
+            .setRemoveAudio(true)
+            .setEffects(
+                new Effects(
+                    ImmutableList.of(createPitchChangingAudioProcessor(/* pitch= */ 2f)),
+                    /* videoEffects= */ ImmutableList.of()))
+            .build();
+    EditedMediaItem silenceItem =
+        new EditedMediaItem.Builder(mediaItem)
+            .setRemoveAudio(true)
+            .setEffects(
+                new Effects(
+                    ImmutableList.of(createPitchChangingAudioProcessor(/* pitch= */ 2f)),
+                    /* videoEffects= */ ImmutableList.of()))
+            .build();
+    EditedMediaItemSequence sequence =
+        new EditedMediaItemSequence(ImmutableList.of(silenceItem, silenceWithEffectsItem));
+    Composition composition =
+        new Composition.Builder(ImmutableList.of(sequence))
+            .experimentalSetForceAudioTrack(true)
+            .setTransmuxVideo(true)
+            .build();
+
+    transformer.start(composition, outputPath);
+    TransformerTestRunner.runLooper(transformer);
+
+    DumpFileAsserts.assertOutput(
+        context,
+        checkNotNull(testMuxerHolder.testMuxer),
+        getDumpFileName(FILE_AUDIO_RAW_VIDEO + ".silence_then_silence-effects"));
+  }
+
+  @Test
+  public void concatenateSilenceAndSilence_withEffectsAndTransmuxVideo_completesSuccessfully()
+      throws Exception {
+    Transformer transformer =
+        createTransformerBuilder(testMuxerHolder, /* enableFallback= */ false).build();
+    MediaItem mediaItem = MediaItem.fromUri(ASSET_URI_PREFIX + FILE_AUDIO_RAW_VIDEO);
+    EditedMediaItem firstItem =
+        new EditedMediaItem.Builder(mediaItem)
+            .setRemoveAudio(true)
+            .setEffects(
+                new Effects(
+                    ImmutableList.of(createPitchChangingAudioProcessor(/* pitch= */ 2f)),
+                    /* videoEffects= */ ImmutableList.of()))
+            .build();
+    EditedMediaItem secondItem =
+        new EditedMediaItem.Builder(mediaItem)
+            .setRemoveAudio(true)
+            .setEffects(
+                new Effects(
+                    ImmutableList.of(createPitchChangingAudioProcessor(/* pitch= */ 2f)),
+                    /* videoEffects= */ ImmutableList.of()))
+            .build();
+    EditedMediaItemSequence sequence =
+        new EditedMediaItemSequence(ImmutableList.of(firstItem, secondItem));
+    Composition composition =
+        new Composition.Builder(ImmutableList.of(sequence))
+            .experimentalSetForceAudioTrack(true)
+            .setTransmuxVideo(true)
+            .build();
+
+    transformer.start(composition, outputPath);
+    TransformerTestRunner.runLooper(transformer);
+
+    DumpFileAsserts.assertOutput(
+        context,
+        checkNotNull(testMuxerHolder.testMuxer),
+        getDumpFileName(FILE_AUDIO_RAW_VIDEO + ".silence_then_silence_with_effects"));
+  }
+
   @Test
   public void concatenateTwoAudioItems_withSameFormat_completesSuccessfully() throws Exception {
     Transformer transformer =