Seek Bug when there is a gap at end in the composition

demos/composition/src/main/java/androidx/media3/demo/composition/CompositionPreviewViewModel.kt

@@ -597,6 +597,51 @@ class CompositionPreviewViewModel(application: Application) : AndroidViewModel(a
     compositionPlayer.play()
   }
 
+  /**
+   * Reproduces a CompositionPlayer stuck-seek bug:
+   *   - Requires the composition to end in a GapMediaItem and FrameConsumer to be enabled.
+   *   - Step 1: seekTo(duration-1) — lands the playhead in the trailing gap. If the gap emits
+   *     no frame, Media3's onFrameProcessed never clears waitingForFrameAfterSeek.
+   *   - Step 2: seekTo(0) — silently DEFERRED behind the latched flag.
+   *   - Step 3: play() — no visible playback (position never returns to 0).
+   * Watch `adb logcat -s SeekDbg RepDbg` while pressing the button.
+   */
+  fun reproduceStuckSeekBug() {
+    viewModelScope.launch {
+      val player = compositionPlayer
+      val duration = player.duration
+      Log.d("RepDbg", "start: duration=$duration currentPos=${player.currentPosition}")
+      if (duration <= 0) {
+        Log.d("RepDbg", "abort: duration<=0. Add media + a trailing Gap before pressing.")
+        return@launch
+      }
+
+      // Step 1: land the playhead at duration-1. Position moves 0 → duration-1, a frame
+      // is emitted, onFrameProcessed clears the flag.
+      Log.d("RepDbg", "step1: seekTo(${duration - 1}) — expect PROPAGATING + onFrameProcessed clears flag")
+      player.seekTo(duration - 1)
+      kotlinx.coroutines.delay(1000)
+      Log.d("RepDbg", "step1 done: currentPos=${player.currentPosition}")
+
+      // Step 2: redundant seek to the *same* position (mirrors Squirrel's "post-scrub refresh
+      // seek to <confirmed current pos>"). No-op seek → no frame delivered → onFrameProcessed
+      // never fires → waitingForFrameAfterSeek stays latched.
+      Log.d("RepDbg", "step2: seekTo(${duration - 1}) again (no-op) — expect PROPAGATING but NO onFrameProcessed follows")
+      player.seekTo(duration - 1)
+      kotlinx.coroutines.delay(1000)
+      Log.d("RepDbg", "step2 done: currentPos=${player.currentPosition}")
+
+      // Step 3: any follow-up seek is now silently DEFERRED behind the latched flag.
+      Log.d("RepDbg", "step3: seekTo(0) — expect DEFERRED (flag latched)")
+      player.seekTo(0)
+      kotlinx.coroutines.delay(200)
+      Log.d("RepDbg", "step3 done: currentPos=${player.currentPosition} (should still be at end)")
+
+      Log.d("RepDbg", "step4: play() — expect no visible playback")
+      player.play()
+    }
+  }
+
   fun exportComposition() {
     // Cancel and clean up files from any ongoing export.
     cancelExport()
@@ -790,9 +835,15 @@ class CompositionPreviewViewModel(application: Application) : AndroidViewModel(a
 
       val sequenceBuilder = EditedMediaItemSequence.Builder(trackTypes)
 
+      Log.d(
+        "RepDbg",
+        "buildSequence[$sequenceIndex] items=${sequenceItems.size} " +
+          "types=${sequenceItems.joinToString(",") { it.javaClass.simpleName }}",
+      )
       for (item in sequenceItems) {
         when (item) {
           is Gap -> {
+            Log.d("RepDbg", "  addGap durationUs=${item.durationUs}")
             sequenceBuilder.addGap(item.durationUs)
           }
           is Media -> {
@@ -826,6 +877,7 @@ class CompositionPreviewViewModel(application: Application) : AndroidViewModel(a
                 // Setting duration explicitly is only required for preview with CompositionPlayer,
                 // and is not needed for export with Transformer.
                 .setDurationUs(item.durationUs)
+            Log.d("RepDbg", "  addMedia durationUs=${item.durationUs} uri=${item.uri}")
             sequenceBuilder.addItem(itemBuilder.build())
           }
         }

demos/composition/src/main/java/androidx/media3/demo/composition/ui/CompositionPreviewPane.kt

@@ -238,6 +238,12 @@ internal fun CompositionPreviewPane(
       Button(onClick = { viewModel.play() }, enabled = uiState.isCompositionSet) {
         Text(text = stringResource(R.string.play))
       }
+      Button(
+        onClick = { viewModel.reproduceStuckSeekBug() },
+        enabled = uiState.isCompositionSet,
+      ) {
+        Text(text = "Reproduce stuck-seek bug")
+      }
       Button(onClick = onOpenExportOptions) {
         Text(text = stringResource(R.string.export_settings))
       }

libraries/effect_ndk/build.gradle.kts

@@ -12,7 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-plugins { id("media3.android-library") }
+plugins {
+  id("media3.android-library")
+}
 
 android {
   namespace = "androidx.media3.effect.ndk"

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

@@ -931,6 +931,10 @@ public void setScrubbingModeEnabled(boolean scrubbingModeEnabled) {
               : this.playWhenReadyChangeReason);
 
       // Bypass debouncing for the final seek when scrubbing ends.
+      Log.d(
+          "SeekDbg",
+          "setScrubbingModeEnabled(false) CLEARING flag; pendingSeekPositionMs="
+              + pendingSeekPositionMs);
       waitingForFrameAfterSeek = false;
       if (pendingSeekPositionMs != C.TIME_UNSET) {
         long pendingSeekPosition = pendingSeekPositionMs;
@@ -1191,18 +1195,65 @@ private void handleSeekInternal(long positionMs) {
         "positionMs=%d",
         positionMs);
 
+    Log.d(
+        "SeekDbg",
+        "handleSeekInternal enter positionMs="
+            + positionMs
+            + " frameProcessor="
+            + (frameProcessor != null)
+            + " waitingForFrameAfterSeek="
+            + waitingForFrameAfterSeek
+            + " pendingSeekPositionMs="
+            + pendingSeekPositionMs
+            + " aggregatedContentPos="
+            + getContentPositionMs());
     if (frameProcessor != null) {
       if (waitingForFrameAfterSeek) {
         pendingSeekPositionMs = positionMs;
+        Log.d(
+            "SeekDbg",
+            "handleSeekInternal DEFERRED (flag latched) -> pendingSeekPositionMs=" + positionMs);
         return;
       }
       waitingForFrameAfterSeek = true;
     }
+    Log.d(
+        "SeekDbg", "handleSeekInternal PROPAGATING to inner players positionMs=" + positionMs);
     CompositionPlayerInternal compositionPlayerInternal =
         checkNotNull(this.compositionPlayerInternal);
     compositionPlayerInternal.startSeek(positionMs);
     for (int i = 0; i < playerHolders.size(); i++) {
+      androidx.media3.exoplayer.ExoPlayer innerPlayer = playerHolders.get(i).player;
+      Log.d(
+          "SeekDbg",
+          "  inner["
+              + i
+              + "] PRE-seek state="
+              + innerPlayer.getPlaybackState()
+              + " contentPos="
+              + innerPlayer.getContentPosition()
+              + " duration="
+              + innerPlayer.getDuration()
+              + " playWhenReady="
+              + innerPlayer.getPlayWhenReady()
+              + " mediaItemCount="
+              + innerPlayer.getMediaItemCount()
+              + " currentMediaItemIndex="
+              + innerPlayer.getCurrentMediaItemIndex());
       playerHolders.get(i).player.seekTo(positionMs);
+      Log.d(
+          "SeekDbg",
+          "  inner["
+              + i
+              + "] POST-seek state="
+              + innerPlayer.getPlaybackState()
+              + " contentPos="
+              + innerPlayer.getContentPosition()
+              + " currentMediaItemIndex="
+              + innerPlayer.getCurrentMediaItemIndex()
+              + " (requested "
+              + positionMs
+              + ")");
       // Flush the HardwareBufferFrameReader and FrameAggregator after the player seeks to ensure
       // frames from before the seek do not race with the flush calls.
       if (frameProcessor != null) {
@@ -1224,6 +1275,12 @@ private void handleSeekInternal(long positionMs) {
       }
     }
     compositionPlayerInternal.endSeek();
+    Log.d(
+        "SeekDbg",
+        "handleSeekInternal DONE requestedMs="
+            + positionMs
+            + " aggregatedContentPos="
+            + getContentPositionMs());
   }
 
   @Override
@@ -1566,6 +1623,16 @@ private void prepareCompositionPlayerInternal() {
   }
 
   private void setCompositionInternal(Composition composition, long startPositionMs) {
+    Log.d(
+        "SeekDbg",
+        "setCompositionInternal startPositionMs="
+            + startPositionMs
+            + " CLEARING waitingForFrameAfterSeek (was "
+            + waitingForFrameAfterSeek
+            + ") pendingSeekPositionMs=(was "
+            + pendingSeekPositionMs
+            + ") priorAggregatedPos="
+            + getContentPositionMs());
     waitingForFrameAfterSeek = false;
     pendingSeekPositionMs = C.TIME_UNSET;
     for (int i = 0; i < playerHolders.size(); i++) {
@@ -2545,11 +2612,22 @@ public void onVideoSizeChanged(VideoSize videoSize) {
     public void onFrameProcessed() {
       applicationHandler.post(
           () -> {
+            Log.d(
+                "SeekDbg",
+                "onFrameProcessed waitingForFrameAfterSeek="
+                    + waitingForFrameAfterSeek
+                    + " pendingSeekPositionMs="
+                    + pendingSeekPositionMs
+                    + " aggregatedContentPos="
+                    + getContentPositionMs());
             if (waitingForFrameAfterSeek) {
               waitingForFrameAfterSeek = false;
               if (pendingSeekPositionMs != C.TIME_UNSET) {
                 long pendingSeekPosition = pendingSeekPositionMs;
                 pendingSeekPositionMs = C.TIME_UNSET;
+                Log.d(
+                    "SeekDbg",
+                    "onFrameProcessed FLUSHING pending seek -> " + pendingSeekPosition);
                 handleSeekInternal(pendingSeekPosition);
               }
             }