diff --git a/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/BaseSamplePipeline.java b/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/BaseSamplePipeline.java
index 95b523466f..b54a27669d 100644
--- a/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/BaseSamplePipeline.java
+++ b/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/BaseSamplePipeline.java
@@ -18,12 +18,14 @@ package com.google.android.exoplayer2.transformer;
 
 import static com.google.android.exoplayer2.util.Assertions.checkNotNull;
 import static com.google.android.exoplayer2.util.Assertions.checkStateNotNull;
+import static java.lang.Math.max;
 
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.decoder.DecoderInputBuffer;
 import com.google.android.exoplayer2.util.MimeTypes;
+import com.google.android.exoplayer2.util.Util;
 import java.nio.ByteBuffer;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import org.checkerframework.checker.nullness.qual.RequiresNonNull;
@@ -38,6 +40,7 @@ import org.checkerframework.checker.nullness.qual.RequiresNonNull;
 
   @Nullable private DecoderInputBuffer inputBuffer;
   private boolean muxerWrapperTrackAdded;
+  private long currentPositionMs;
   private boolean isEnded;
 
   public BaseSamplePipeline(
@@ -65,9 +68,11 @@ import org.checkerframework.checker.nullness.qual.RequiresNonNull;
 
   @Override
   public void queueInputBuffer() throws TransformationException {
-    checkNotNull(inputBuffer);
+    DecoderInputBuffer inputBuffer = checkNotNull(this.inputBuffer);
+    currentPositionMs =
+        max(currentPositionMs, Util.usToMs(inputBuffer.timeUs - streamStartPositionUs));
     checkNotNull(inputBuffer.data);
-    if (!shouldDropInputBuffer()) {
+    if (!shouldDropInputBuffer(inputBuffer)) {
       queueInputBufferInternal();
     }
   }
@@ -82,6 +87,11 @@ import org.checkerframework.checker.nullness.qual.RequiresNonNull;
     return isEnded;
   }
 
+  @Override
+  public long getCurrentPositionMs() {
+    return currentPositionMs;
+  }
+
   @Nullable
   protected abstract DecoderInputBuffer dequeueInputBufferInternal() throws TransformationException;
 
@@ -103,8 +113,8 @@ import org.checkerframework.checker.nullness.qual.RequiresNonNull;
    * Preprocesses an {@linkplain DecoderInputBuffer input buffer} queued to the pipeline and returns
    * whether it should be dropped.
    */
-  @RequiresNonNull({"inputBuffer", "inputBuffer.data"})
-  private boolean shouldDropInputBuffer() {
+  @RequiresNonNull("#1.data")
+  private boolean shouldDropInputBuffer(DecoderInputBuffer inputBuffer) {
     ByteBuffer inputBytes = inputBuffer.data;
 
     if (sefVideoSlowMotionFlattener == null || inputBuffer.isEndOfStream()) {
@@ -112,7 +122,6 @@ import org.checkerframework.checker.nullness.qual.RequiresNonNull;
     }
 
     long presentationTimeUs = inputBuffer.timeUs - streamOffsetUs;
-    DecoderInputBuffer inputBuffer = this.inputBuffer;
     boolean shouldDropInputBuffer =
         sefVideoSlowMotionFlattener.dropOrTransformSample(inputBytes, presentationTimeUs);
     if (shouldDropInputBuffer) {
diff --git a/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/ExoPlayerAssetLoader.java b/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/ExoPlayerAssetLoader.java
index f39d62e382..3f5d649ccc 100644
--- a/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/ExoPlayerAssetLoader.java
+++ b/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/ExoPlayerAssetLoader.java
@@ -20,12 +20,7 @@ import static com.google.android.exoplayer2.DefaultLoadControl.DEFAULT_BUFFER_FO
 import static com.google.android.exoplayer2.DefaultLoadControl.DEFAULT_BUFFER_FOR_PLAYBACK_MS;
 import static com.google.android.exoplayer2.DefaultLoadControl.DEFAULT_MAX_BUFFER_MS;
 import static com.google.android.exoplayer2.DefaultLoadControl.DEFAULT_MIN_BUFFER_MS;
-import static com.google.android.exoplayer2.transformer.Transformer.PROGRESS_STATE_AVAILABLE;
-import static com.google.android.exoplayer2.transformer.Transformer.PROGRESS_STATE_NO_TRANSFORMATION;
-import static com.google.android.exoplayer2.transformer.Transformer.PROGRESS_STATE_UNAVAILABLE;
-import static com.google.android.exoplayer2.transformer.Transformer.PROGRESS_STATE_WAITING_FOR_AVAILABILITY;
 import static com.google.android.exoplayer2.util.Assertions.checkNotNull;
-import static java.lang.Math.min;
 
 import android.content.Context;
 import android.os.Handler;
@@ -48,12 +43,15 @@ import com.google.android.exoplayer2.source.MediaSource;
 import com.google.android.exoplayer2.text.TextOutput;
 import com.google.android.exoplayer2.trackselection.DefaultTrackSelector;
 import com.google.android.exoplayer2.util.Clock;
+import com.google.android.exoplayer2.util.Util;
 import com.google.android.exoplayer2.video.VideoRendererEventListener;
 
 /* package */ final class ExoPlayerAssetLoader {
 
   public interface Listener {
 
+    void onDurationMs(long durationMs);
+
     void onTrackRegistered();
 
     void onAllTracksRegistered();
@@ -74,7 +72,6 @@ import com.google.android.exoplayer2.video.VideoRendererEventListener;
   private final Clock clock;
 
   @Nullable private ExoPlayer player;
-  private @Transformer.ProgressState int progressState;
 
   public ExoPlayerAssetLoader(
       Context context,
@@ -89,7 +86,6 @@ import com.google.android.exoplayer2.video.VideoRendererEventListener;
     this.mediaSourceFactory = mediaSourceFactory;
     this.looper = looper;
     this.clock = clock;
-    progressState = PROGRESS_STATE_NO_TRANSFORMATION;
   }
 
   public void start(MediaItem mediaItem, Listener listener) {
@@ -125,22 +121,9 @@ import com.google.android.exoplayer2.video.VideoRendererEventListener;
     player.setMediaItem(mediaItem);
     player.addListener(new PlayerListener(listener));
     player.prepare();
-
-    progressState = PROGRESS_STATE_WAITING_FOR_AVAILABILITY;
-  }
-
-  public @Transformer.ProgressState int getProgress(ProgressHolder progressHolder) {
-    if (progressState == PROGRESS_STATE_AVAILABLE) {
-      Player player = checkNotNull(this.player);
-      long durationMs = player.getDuration();
-      long positionMs = player.getCurrentPosition();
-      progressHolder.progress = min((int) (positionMs * 100 / durationMs), 99);
-    }
-    return progressState;
   }
 
   public void release() {
-    progressState = PROGRESS_STATE_NO_TRANSFORMATION;
     if (player != null) {
       player.release();
       player = null;
@@ -191,6 +174,7 @@ import com.google.android.exoplayer2.video.VideoRendererEventListener;
   private final class PlayerListener implements Player.Listener {
 
     private final Listener listener;
+    private boolean hasSentDuration;
 
     public PlayerListener(Listener listener) {
       this.listener = listener;
@@ -205,20 +189,14 @@ import com.google.android.exoplayer2.video.VideoRendererEventListener;
 
     @Override
     public void onTimelineChanged(Timeline timeline, int reason) {
-      if (progressState != PROGRESS_STATE_WAITING_FOR_AVAILABILITY) {
+      if (hasSentDuration) {
         return;
       }
       Timeline.Window window = new Timeline.Window();
       timeline.getWindow(/* windowIndex= */ 0, window);
       if (!window.isPlaceholder) {
-        long durationUs = window.durationUs;
-        // Make progress permanently unavailable if the duration is unknown, so that it doesn't jump
-        // to a high value at the end of the transformation if the duration is set once the media is
-        // entirely loaded.
-        progressState =
-            durationUs <= 0 || durationUs == C.TIME_UNSET
-                ? PROGRESS_STATE_UNAVAILABLE
-                : PROGRESS_STATE_AVAILABLE;
+        listener.onDurationMs(Util.usToMs(window.durationUs));
+        hasSentDuration = true;
         checkNotNull(player).play();
       }
     }
diff --git a/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/SamplePipeline.java b/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/SamplePipeline.java
index 7d592bbc84..3fc6ba231d 100644
--- a/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/SamplePipeline.java
+++ b/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/SamplePipeline.java
@@ -49,4 +49,10 @@ import com.google.android.exoplayer2.decoder.DecoderInputBuffer;
 
   /** Releases all resources held by the pipeline. */
   void release();
+
+  /**
+   * Returns the current timestamp being processed in the track, in milliseconds. This is the
+   * largest timestamp queued minus the stream start time, or 0 if no input has been queued.
+   */
+  long getCurrentPositionMs();
 }
diff --git a/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/TransformerInternal.java b/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/TransformerInternal.java
index 41c6602401..48baba028d 100644
--- a/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/TransformerInternal.java
+++ b/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/TransformerInternal.java
@@ -16,6 +16,12 @@
 
 package com.google.android.exoplayer2.transformer;
 
+import static com.google.android.exoplayer2.transformer.Transformer.PROGRESS_STATE_AVAILABLE;
+import static com.google.android.exoplayer2.transformer.Transformer.PROGRESS_STATE_NO_TRANSFORMATION;
+import static com.google.android.exoplayer2.transformer.Transformer.PROGRESS_STATE_UNAVAILABLE;
+import static com.google.android.exoplayer2.transformer.Transformer.PROGRESS_STATE_WAITING_FOR_AVAILABILITY;
+import static java.lang.Math.min;
+
 import android.content.Context;
 import android.os.Looper;
 import androidx.annotation.Nullable;
@@ -32,6 +38,8 @@ import com.google.android.exoplayer2.util.Effect;
 import com.google.android.exoplayer2.util.FrameProcessor;
 import com.google.android.exoplayer2.util.MimeTypes;
 import com.google.common.collect.ImmutableList;
+import java.util.ArrayList;
+import java.util.List;
 
 /* package */ final class TransformerInternal {
 
@@ -50,6 +58,10 @@ import com.google.common.collect.ImmutableList;
   private final FrameProcessor.Factory frameProcessorFactory;
   private final DebugViewProvider debugViewProvider;
   private final ExoPlayerAssetLoader exoPlayerAssetLoader;
+  private final List<SamplePipeline> samplePipelines;
+
+  private @Transformer.ProgressState int progressState;
+  private long durationMs;
 
   public TransformerInternal(
       Context context,
@@ -74,6 +86,8 @@ import com.google.common.collect.ImmutableList;
     exoPlayerAssetLoader =
         new ExoPlayerAssetLoader(
             context, removeAudio, removeVideo, mediaSourceFactory, looper, clock);
+    samplePipelines = new ArrayList<>(/* initialCapacity= */ 2);
+    progressState = PROGRESS_STATE_NO_TRANSFORMATION;
   }
 
   public void start(
@@ -84,16 +98,34 @@ import com.google.common.collect.ImmutableList;
     AssetLoaderListener assetLoaderListener =
         new AssetLoaderListener(mediaItem, muxerWrapper, listener, fallbackListener);
     exoPlayerAssetLoader.start(mediaItem, assetLoaderListener);
+    progressState = PROGRESS_STATE_WAITING_FOR_AVAILABILITY;
   }
 
   public @Transformer.ProgressState int getProgress(ProgressHolder progressHolder) {
-    return exoPlayerAssetLoader.getProgress(progressHolder);
+    if (progressState == PROGRESS_STATE_AVAILABLE) {
+      long positionMs = getCurrentPositionMs();
+      progressHolder.progress = min((int) (positionMs * 100 / durationMs), 99);
+    }
+    return progressState;
   }
 
   public void release() {
+    samplePipelines.clear();
+    progressState = PROGRESS_STATE_NO_TRANSFORMATION;
     exoPlayerAssetLoader.release();
   }
 
+  private long getCurrentPositionMs() {
+    if (samplePipelines.isEmpty()) {
+      return 0;
+    }
+    long positionMsSum = 0;
+    for (int i = 0; i < samplePipelines.size(); i++) {
+      positionMsSum += samplePipelines.get(i).getCurrentPositionMs();
+    }
+    return positionMsSum / samplePipelines.size();
+  }
+
   private class AssetLoaderListener implements ExoPlayerAssetLoader.Listener {
 
     private final MediaItem mediaItem;
@@ -114,6 +146,18 @@ import com.google.common.collect.ImmutableList;
       this.fallbackListener = fallbackListener;
     }
 
+    @Override
+    public void onDurationMs(long durationMs) {
+      // Make progress permanently unavailable if the duration is unknown, so that it doesn't jump
+      // to a high value at the end of the transformation if the duration is set once the media is
+      // entirely loaded.
+      progressState =
+          durationMs <= 0 || durationMs == C.TIME_UNSET
+              ? PROGRESS_STATE_UNAVAILABLE
+              : PROGRESS_STATE_AVAILABLE;
+      TransformerInternal.this.durationMs = durationMs;
+    }
+
     @Override
     public void onTrackRegistered() {
       trackRegistered = true;
@@ -132,7 +176,10 @@ import com.google.common.collect.ImmutableList;
     public SamplePipeline onTrackAdded(
         Format format, long streamStartPositionUs, long streamOffsetUs)
         throws TransformationException {
-      return getSamplePipeline(format, streamStartPositionUs, streamOffsetUs);
+      SamplePipeline samplePipeline =
+          getSamplePipeline(format, streamStartPositionUs, streamOffsetUs);
+      samplePipelines.add(samplePipeline);
+      return samplePipeline;
     }
 
     @Override