Fix SpeedChangingAudioProcessor handling of EMPTY_BUFFER.

PiperOrigin-RevId: 490265564

library/common/src/main/java/com/google/android/exoplayer2/audio/AudioProcessingPipeline.java

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.audio;
 
+import static com.google.android.exoplayer2.audio.AudioProcessor.EMPTY_BUFFER;
 import static com.google.android.exoplayer2.util.Assertions.checkState;
 
 import androidx.annotation.Nullable;
@@ -22,7 +23,6 @@ import com.google.android.exoplayer2.audio.AudioProcessor.AudioFormat;
 import com.google.common.collect.ImmutableList;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.nio.ByteBuffer;
-import java.nio.ByteOrder;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -67,10 +67,6 @@ import java.util.List;
  */
 public final class AudioProcessingPipeline {
 
-  /** An empty, direct {@link ByteBuffer}. */
-  private static final ByteBuffer EMPTY_BUFFER =
-      ByteBuffer.allocateDirect(0).order(ByteOrder.nativeOrder());
-
   /** The {@link AudioProcessor} instances passed to {@link AudioProcessingPipeline}. */
   private final ImmutableList<AudioProcessor> audioProcessors;
   /**
@@ -321,13 +317,6 @@ public final class AudioProcessingPipeline {
             index > 0
                 ? outputBuffers[index - 1]
                 : inputBuffer.hasRemaining() ? inputBuffer : EMPTY_BUFFER;
-        if (input == AudioProcessor.EMPTY_BUFFER) {
-          // TODO(internal b/198772621): compare to how it was done in DefaultAudioSink to make sure
-          // this is not unnecessarily complicated.
-          // Queueing AudioProcessor.EMPTY_BUFFER to an AudioProcessor might lead to unexpected
-          // behaviour (see [Internal: b/259393434]).
-          input = EMPTY_BUFFER;
-        }
         long inputBytes = input.remaining();
         audioProcessor.queueInput(input);
         outputBuffers[index] = audioProcessor.getOutput();

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

@@ -108,7 +108,9 @@ import java.nio.ByteBuffer;
       }
     } else {
       ByteBuffer buffer = replaceOutputBuffer(/* size= */ inputBuffer.remaining());
-      buffer.put(inputBuffer);
+      if (inputBuffer.hasRemaining()) {
+        buffer.put(inputBuffer);
+      }
       buffer.flip();
     }
     bytesRead += inputBuffer.position() - startPosition;