diff --git a/extensions/gvr/build.gradle b/extensions/gvr/build.gradle
index f146ba4df6..87e72939c5 100644
--- a/extensions/gvr/build.gradle
+++ b/extensions/gvr/build.gradle
@@ -26,6 +26,7 @@ android {
 
 dependencies {
     implementation project(modulePrefix + 'library-core')
+    implementation 'com.android.support:support-annotations:' + supportLibraryVersion
     implementation 'com.google.vr:sdk-audio:1.80.0'
 }
 
diff --git a/extensions/gvr/src/main/java/com/google/android/exoplayer2/ext/gvr/GvrAudioProcessor.java b/extensions/gvr/src/main/java/com/google/android/exoplayer2/ext/gvr/GvrAudioProcessor.java
index 8d71f551cd..1b595d6886 100644
--- a/extensions/gvr/src/main/java/com/google/android/exoplayer2/ext/gvr/GvrAudioProcessor.java
+++ b/extensions/gvr/src/main/java/com/google/android/exoplayer2/ext/gvr/GvrAudioProcessor.java
@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.ext.gvr;
 
+import android.support.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.ExoPlayerLibraryInfo;
 import com.google.android.exoplayer2.Format;
@@ -39,7 +40,7 @@ public final class GvrAudioProcessor implements AudioProcessor {
 
   private int sampleRateHz;
   private int channelCount;
-  private GvrAudioSurround gvrAudioSurround;
+  @Nullable private GvrAudioSurround gvrAudioSurround;
   private ByteBuffer buffer;
   private boolean inputEnded;
 
@@ -48,14 +49,13 @@ public final class GvrAudioProcessor implements AudioProcessor {
   private float y;
   private float z;
 
-  /**
-   * Creates a new GVR audio processor.
-   */
+  /** Creates a new GVR audio processor. */
   public GvrAudioProcessor() {
     // Use the identity for the initial orientation.
     w = 1f;
     sampleRateHz = Format.NO_VALUE;
     channelCount = Format.NO_VALUE;
+    buffer = EMPTY_BUFFER;
   }
 
   /**
@@ -77,9 +77,11 @@ public final class GvrAudioProcessor implements AudioProcessor {
     }
   }
 
+  @SuppressWarnings("ReferenceEquality")
   @Override
-  public synchronized boolean configure(int sampleRateHz, int channelCount,
-      @C.Encoding int encoding) throws UnhandledFormatException {
+  public synchronized boolean configure(
+      int sampleRateHz, int channelCount, @C.Encoding int encoding)
+      throws UnhandledFormatException {
     if (encoding != C.ENCODING_PCM_16BIT) {
       maybeReleaseGvrAudioSurround();
       throw new UnhandledFormatException(sampleRateHz, channelCount, encoding);
@@ -116,7 +118,7 @@ public final class GvrAudioProcessor implements AudioProcessor {
     gvrAudioSurround = new GvrAudioSurround(surroundFormat, sampleRateHz, channelCount,
         FRAMES_PER_OUTPUT_BUFFER);
     gvrAudioSurround.updateNativeOrientation(w, x, y, z);
-    if (buffer == null) {
+    if (buffer == EMPTY_BUFFER) {
       buffer = ByteBuffer.allocateDirect(FRAMES_PER_OUTPUT_BUFFER * OUTPUT_FRAME_SIZE)
           .order(ByteOrder.nativeOrder());
     }
@@ -179,10 +181,11 @@ public final class GvrAudioProcessor implements AudioProcessor {
   @Override
   public synchronized void reset() {
     maybeReleaseGvrAudioSurround();
+    updateOrientation(/* w= */ 1f, /* x= */ 0f, /* y= */ 0f, /* z= */ 0f);
     inputEnded = false;
-    buffer = null;
     sampleRateHz = Format.NO_VALUE;
     channelCount = Format.NO_VALUE;
+    buffer = EMPTY_BUFFER;
   }
 
   private void maybeReleaseGvrAudioSurround() {
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/audio/AudioProcessor.java b/library/core/src/main/java/com/google/android/exoplayer2/audio/AudioProcessor.java
index 8a3d624222..7aa4a8e6c8 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/audio/AudioProcessor.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/audio/AudioProcessor.java
@@ -22,19 +22,17 @@ import java.nio.ByteOrder;
 /**
  * Interface for audio processors, which take audio data as input and transform it, potentially
  * modifying its channel count, encoding and/or sample rate.
- * <p>
- * Call {@link #configure(int, int, int)} to configure the processor to receive input audio, then
- * call {@link #isActive()} to determine whether the processor is active.
- * {@link #queueInput(ByteBuffer)}, {@link #queueEndOfStream()}, {@link #getOutput()},
- * {@link #isEnded()}, {@link #getOutputChannelCount()}, {@link #getOutputEncoding()} and
- * {@link #getOutputSampleRateHz()} may only be called if the processor is active. Call
- * {@link #reset()} to reset the processor to its unconfigured state.
+ *
+ * <p>Call {@link #configure(int, int, int)} to configure the processor to receive input audio, then
+ * call {@link #isActive()} to determine whether the processor is active. {@link
+ * #queueInput(ByteBuffer)}, {@link #queueEndOfStream()}, {@link #getOutput()}, {@link #isEnded()},
+ * {@link #getOutputChannelCount()}, {@link #getOutputEncoding()} and {@link
+ * #getOutputSampleRateHz()} may only be called if the processor is active. Call {@link #reset()} to
+ * reset the processor to its unconfigured state and release any resources.
  */
 public interface AudioProcessor {
 
-  /**
-   * Exception thrown when a processor can't be configured for a given input audio format.
-   */
+  /** Exception thrown when a processor can't be configured for a given input audio format. */
   final class UnhandledFormatException extends Exception {
 
     public UnhandledFormatException(int sampleRateHz, int channelCount, @C.Encoding int encoding) {
@@ -44,33 +42,26 @@ public interface AudioProcessor {
 
   }
 
-  /**
-   * An empty, direct {@link ByteBuffer}.
-   */
+  /** An empty, direct {@link ByteBuffer}. */
   ByteBuffer EMPTY_BUFFER = ByteBuffer.allocateDirect(0).order(ByteOrder.nativeOrder());
 
   /**
-   * Configures the processor to process input audio with the specified format. After calling this
-   * method, {@link #isActive()} returns whether the processor needs to handle buffers; if not, the
-   * processor will not accept any buffers until it is reconfigured. Returns {@code true} if the
-   * processor must be flushed, or if the value returned by {@link #isActive()} has changed as a
-   * result of the call. If it's active, {@link #getOutputSampleRateHz()},
-   * {@link #getOutputChannelCount()} and {@link #getOutputEncoding()} return the processor's output
-   * format.
+   * Configures the processor to process input audio with the specified format and returns whether
+   * to {@link #flush()} it. After calling this method, {@link #isActive()} returns whether the
+   * processor needs to handle buffers; if not, the processor will not accept any buffers until it
+   * is reconfigured. If the processor is active, {@link #getOutputSampleRateHz()}, {@link
+   * #getOutputChannelCount()} and {@link #getOutputEncoding()} return its output format.
    *
    * @param sampleRateHz The sample rate of input audio in Hz.
    * @param channelCount The number of interleaved channels in input audio.
    * @param encoding The encoding of input audio.
-   * @return {@code true} if the processor must be flushed or the value returned by
-   *     {@link #isActive()} has changed as a result of the call.
+   * @return Whether to {@link #flush()} the processor.
    * @throws UnhandledFormatException Thrown if the specified format can't be handled as input.
    */
   boolean configure(int sampleRateHz, int channelCount, @C.Encoding int encoding)
       throws UnhandledFormatException;
 
-  /**
-   * Returns whether the processor is configured and active.
-   */
+  /** Returns whether the processor is configured and active. */
   boolean isActive();
 
   /**
@@ -130,14 +121,9 @@ public interface AudioProcessor {
    */
   boolean isEnded();
 
-  /**
-   * Clears any state in preparation for receiving a new stream of input buffers.
-   */
+  /** Clears any state in preparation for receiving a new stream of input buffers. */
   void flush();
 
-  /**
-   * Resets the processor to its unconfigured state.
-   */
+  /** Resets the processor to its unconfigured state. */
   void reset();
-
 }
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/audio/ChannelMappingAudioProcessor.java b/library/core/src/main/java/com/google/android/exoplayer2/audio/ChannelMappingAudioProcessor.java
index 50b484b938..e53eb08c83 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/audio/ChannelMappingAudioProcessor.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/audio/ChannelMappingAudioProcessor.java
@@ -15,9 +15,11 @@
  */
 package com.google.android.exoplayer2.audio;
 
+import android.support.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.C.Encoding;
 import com.google.android.exoplayer2.Format;
+import com.google.android.exoplayer2.util.Assertions;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.util.Arrays;
@@ -30,17 +32,15 @@ import java.util.Arrays;
 
   private int channelCount;
   private int sampleRateHz;
-  private int[] pendingOutputChannels;
+  private @Nullable int[] pendingOutputChannels;
 
   private boolean active;
-  private int[] outputChannels;
+  private @Nullable int[] outputChannels;
   private ByteBuffer buffer;
   private ByteBuffer outputBuffer;
   private boolean inputEnded;
 
-  /**
-   * Creates a new processor that applies a channel mapping.
-   */
+  /** Creates a new processor that applies a channel mapping. */
   public ChannelMappingAudioProcessor() {
     buffer = EMPTY_BUFFER;
     outputBuffer = EMPTY_BUFFER;
@@ -52,9 +52,11 @@ import java.util.Arrays;
    * Resets the channel mapping. After calling this method, call {@link #configure(int, int, int)}
    * to start using the new channel map.
    *
+   * @param outputChannels The mapping from input to output channel indices, or {@code null} to
+   *     leave the input unchanged.
    * @see AudioSink#configure(int, int, int, int, int[], int, int)
    */
-  public void setChannelMap(int[] outputChannels) {
+  public void setChannelMap(@Nullable int[] outputChannels) {
     pendingOutputChannels = outputChannels;
   }
 
@@ -110,6 +112,7 @@ import java.util.Arrays;
 
   @Override
   public void queueInput(ByteBuffer inputBuffer) {
+    Assertions.checkState(outputChannels != null);
     int position = inputBuffer.position();
     int limit = inputBuffer.limit();
     int frameCount = (limit - position) / (2 * channelCount);
@@ -161,6 +164,7 @@ import java.util.Arrays;
     channelCount = Format.NO_VALUE;
     sampleRateHz = Format.NO_VALUE;
     outputChannels = null;
+    pendingOutputChannels = null;
     active = false;
   }
 
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/audio/DefaultAudioSink.java b/library/core/src/main/java/com/google/android/exoplayer2/audio/DefaultAudioSink.java
index ac62ce0951..7270336a08 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/audio/DefaultAudioSink.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/audio/DefaultAudioSink.java
@@ -147,10 +147,9 @@ public final class DefaultAudioSink implements AudioSink {
   private final ArrayDeque<PlaybackParametersCheckpoint> playbackParametersCheckpoints;
 
   @Nullable private Listener listener;
-  /**
-   * Used to keep the audio session active on pre-V21 builds (see {@link #initialize()}).
-   */
-  private AudioTrack keepSessionIdAudioTrack;
+  /** Used to keep the audio session active on pre-V21 builds (see {@link #initialize()}). */
+  @Nullable private AudioTrack keepSessionIdAudioTrack;
+
   private AudioTrack audioTrack;
   private boolean isInputPcm;
   private boolean shouldConvertHighResIntPcmToFloat;
@@ -163,12 +162,12 @@ public final class DefaultAudioSink implements AudioSink {
   private boolean canApplyPlaybackParameters;
   private int bufferSize;
 
-  private PlaybackParameters drainingPlaybackParameters;
+  @Nullable private PlaybackParameters drainingPlaybackParameters;
   private PlaybackParameters playbackParameters;
   private long playbackParametersOffsetUs;
   private long playbackParametersPositionUs;
 
-  private ByteBuffer avSyncHeader;
+  @Nullable private ByteBuffer avSyncHeader;
   private int bytesUntilNextAvSync;
 
   private int pcmFrameSize;
@@ -184,8 +183,8 @@ public final class DefaultAudioSink implements AudioSink {
 
   private AudioProcessor[] audioProcessors;
   private ByteBuffer[] outputBuffers;
-  private ByteBuffer inputBuffer;
-  private ByteBuffer outputBuffer;
+  @Nullable private ByteBuffer inputBuffer;
+  @Nullable private ByteBuffer outputBuffer;
   private byte[] preV21OutputBuffer;
   private int preV21OutputBufferOffset;
   private int drainingAudioProcessorIndex;
@@ -408,7 +407,7 @@ public final class DefaultAudioSink implements AudioSink {
     }
   }
 
-  private void resetAudioProcessors() {
+  private void setupAudioProcessors() {
     ArrayList<AudioProcessor> newAudioProcessors = new ArrayList<>();
     for (AudioProcessor audioProcessor : getAvailableAudioProcessors()) {
       if (audioProcessor.isActive()) {
@@ -420,7 +419,11 @@ public final class DefaultAudioSink implements AudioSink {
     int count = newAudioProcessors.size();
     audioProcessors = newAudioProcessors.toArray(new AudioProcessor[count]);
     outputBuffers = new ByteBuffer[count];
-    for (int i = 0; i < count; i++) {
+    flushAudioProcessors();
+  }
+
+  private void flushAudioProcessors() {
+    for (int i = 0; i < audioProcessors.length; i++) {
       AudioProcessor audioProcessor = audioProcessors[i];
       audioProcessor.flush();
       outputBuffers[i] = audioProcessor.getOutput();
@@ -436,13 +439,6 @@ public final class DefaultAudioSink implements AudioSink {
     releasingConditionVariable.block();
 
     audioTrack = initializeAudioTrack();
-
-    // The old playback parameters may no longer be applicable so try to reset them now.
-    setPlaybackParameters(playbackParameters);
-
-    // Flush and reset active audio processors.
-    resetAudioProcessors();
-
     int audioSessionId = audioTrack.getAudioSessionId();
     if (enablePreV21AudioSessionWorkaround) {
       if (Util.SDK_INT < 21) {
@@ -464,6 +460,10 @@ public final class DefaultAudioSink implements AudioSink {
       }
     }
 
+    // The old playback parameters may no longer be applicable so try to reset them now.
+    setPlaybackParameters(playbackParameters);
+    setupAudioProcessors();
+
     audioTrackPositionTracker.setAudioTrack(
         audioTrack, outputEncoding, outputPcmFrameSize, bufferSize);
     setVolumeInternal();
@@ -533,7 +533,7 @@ public final class DefaultAudioSink implements AudioSink {
         drainingPlaybackParameters = null;
         // The audio processors have drained, so flush them. This will cause any active speed
         // adjustment audio processor to start producing audio with the new parameters.
-        resetAudioProcessors();
+        setupAudioProcessors();
       }
 
       if (startMediaTimeState == START_NOT_SET) {
@@ -849,11 +849,7 @@ public final class DefaultAudioSink implements AudioSink {
       playbackParametersPositionUs = 0;
       inputBuffer = null;
       outputBuffer = null;
-      for (int i = 0; i < audioProcessors.length; i++) {
-        AudioProcessor audioProcessor = audioProcessors[i];
-        audioProcessor.flush();
-        outputBuffers[i] = audioProcessor.getOutput();
-      }
+      flushAudioProcessors();
       handledEndOfStream = false;
       drainingAudioProcessorIndex = C.INDEX_UNSET;
       avSyncHeader = null;
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/audio/FloatResamplingAudioProcessor.java b/library/core/src/main/java/com/google/android/exoplayer2/audio/FloatResamplingAudioProcessor.java
index 215b04821b..e3c91cd344 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/audio/FloatResamplingAudioProcessor.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/audio/FloatResamplingAudioProcessor.java
@@ -17,7 +17,6 @@ package com.google.android.exoplayer2.audio;
 
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
-import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.Util;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
@@ -86,8 +85,6 @@ import java.nio.ByteOrder;
 
   @Override
   public void queueInput(ByteBuffer inputBuffer) {
-    Assertions.checkState(isActive());
-
     boolean isInput32Bit = sourceEncoding == C.ENCODING_PCM_32BIT;
     int position = inputBuffer.position();
     int limit = inputBuffer.limit();
@@ -150,10 +147,10 @@ import java.nio.ByteOrder;
   @Override
   public void reset() {
     flush();
-    buffer = EMPTY_BUFFER;
     sampleRateHz = Format.NO_VALUE;
     channelCount = Format.NO_VALUE;
     sourceEncoding = C.ENCODING_INVALID;
+    buffer = EMPTY_BUFFER;
   }
 
   /**
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/audio/ResamplingAudioProcessor.java b/library/core/src/main/java/com/google/android/exoplayer2/audio/ResamplingAudioProcessor.java
index 01123f3c59..eac0bffd65 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/audio/ResamplingAudioProcessor.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/audio/ResamplingAudioProcessor.java
@@ -28,15 +28,12 @@ import java.nio.ByteOrder;
 
   private int sampleRateHz;
   private int channelCount;
-  @C.PcmEncoding
-  private int encoding;
+  private @C.PcmEncoding int encoding;
   private ByteBuffer buffer;
   private ByteBuffer outputBuffer;
   private boolean inputEnded;
 
-  /**
-   * Creates a new audio processor that converts audio data to {@link C#ENCODING_PCM_16BIT}.
-   */
+  /** Creates a new audio processor that converts audio data to {@link C#ENCODING_PCM_16BIT}. */
   public ResamplingAudioProcessor() {
     sampleRateHz = Format.NO_VALUE;
     channelCount = Format.NO_VALUE;
@@ -59,9 +56,6 @@ import java.nio.ByteOrder;
     this.sampleRateHz = sampleRateHz;
     this.channelCount = channelCount;
     this.encoding = encoding;
-    if (encoding == C.ENCODING_PCM_16BIT) {
-      buffer = EMPTY_BUFFER;
-    }
     return true;
   }
 
@@ -139,6 +133,7 @@ import java.nio.ByteOrder;
         }
         break;
       case C.ENCODING_PCM_16BIT:
+      case C.ENCODING_PCM_FLOAT:
       case C.ENCODING_INVALID:
       case Format.NO_VALUE:
       default:
@@ -177,10 +172,10 @@ import java.nio.ByteOrder;
   @Override
   public void reset() {
     flush();
-    buffer = EMPTY_BUFFER;
     sampleRateHz = Format.NO_VALUE;
     channelCount = Format.NO_VALUE;
     encoding = C.ENCODING_INVALID;
+    buffer = EMPTY_BUFFER;
   }
 
 }
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/audio/SilenceSkippingAudioProcessor.java b/library/core/src/main/java/com/google/android/exoplayer2/audio/SilenceSkippingAudioProcessor.java
index b0550777a2..c2af535838 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/audio/SilenceSkippingAudioProcessor.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/audio/SilenceSkippingAudioProcessor.java
@@ -72,7 +72,6 @@ import java.nio.ByteOrder;
   private int bytesPerFrame;
 
   private boolean enabled;
-  private boolean isActive;
 
   private ByteBuffer buffer;
   private ByteBuffer outputBuffer;
@@ -103,11 +102,13 @@ import java.nio.ByteOrder;
     outputBuffer = EMPTY_BUFFER;
     channelCount = Format.NO_VALUE;
     sampleRateHz = Format.NO_VALUE;
+    maybeSilenceBuffer = new byte[0];
+    paddingBuffer = new byte[0];
   }
 
   /**
-   * Sets whether to skip silence in the input. After calling this method, call {@link
-   * #configure(int, int, int)} to apply the new setting.
+   * Sets whether to skip silence in the input. The new setting will take effect after calling
+   * {@link #flush()}.
    *
    * @param enabled Whether to skip silence in the input.
    */
@@ -131,33 +132,18 @@ import java.nio.ByteOrder;
     if (encoding != C.ENCODING_PCM_16BIT) {
       throw new UnhandledFormatException(sampleRateHz, channelCount, encoding);
     }
-
-    boolean wasActive = isActive;
-    isActive = enabled;
-    if (!isActive) {
-      return wasActive;
-    }
-
-    if (wasActive && this.sampleRateHz == sampleRateHz && this.channelCount == channelCount) {
+    if (this.sampleRateHz == sampleRateHz && this.channelCount == channelCount) {
       return false;
     }
-
     this.sampleRateHz = sampleRateHz;
     this.channelCount = channelCount;
     bytesPerFrame = channelCount * 2;
-    int maybeSilenceBufferSize = durationUsToFrames(MINIMUM_SILENCE_DURATION_US) * bytesPerFrame;
-    if (maybeSilenceBuffer == null || maybeSilenceBuffer.length != maybeSilenceBufferSize) {
-      maybeSilenceBuffer = new byte[maybeSilenceBufferSize];
-    }
-    paddingSize = durationUsToFrames(PADDING_SILENCE_US) * bytesPerFrame;
-    paddingBuffer = new byte[paddingSize];
-    state = STATE_NOISY;
     return true;
   }
 
   @Override
   public boolean isActive() {
-    return isActive;
+    return enabled;
   }
 
   @Override
@@ -221,6 +207,17 @@ import java.nio.ByteOrder;
 
   @Override
   public void flush() {
+    if (isActive()) {
+      int maybeSilenceBufferSize = durationUsToFrames(MINIMUM_SILENCE_DURATION_US) * bytesPerFrame;
+      if (maybeSilenceBuffer.length != maybeSilenceBufferSize) {
+        maybeSilenceBuffer = new byte[maybeSilenceBufferSize];
+      }
+      paddingSize = durationUsToFrames(PADDING_SILENCE_US) * bytesPerFrame;
+      if (paddingBuffer.length != paddingSize) {
+        paddingBuffer = new byte[paddingSize];
+      }
+    }
+    state = STATE_NOISY;
     outputBuffer = EMPTY_BUFFER;
     inputEnded = false;
     skippedFrames = 0;
@@ -230,11 +227,14 @@ import java.nio.ByteOrder;
 
   @Override
   public void reset() {
+    enabled = false;
     flush();
     buffer = EMPTY_BUFFER;
     channelCount = Format.NO_VALUE;
     sampleRateHz = Format.NO_VALUE;
-    maybeSilenceBuffer = null;
+    paddingSize = 0;
+    maybeSilenceBuffer = new byte[0];
+    paddingBuffer = new byte[0];
   }
 
   // Internal methods.
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/audio/SonicAudioProcessor.java b/library/core/src/main/java/com/google/android/exoplayer2/audio/SonicAudioProcessor.java
index 370ddb2809..9beb65bec6 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/audio/SonicAudioProcessor.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/audio/SonicAudioProcessor.java
@@ -15,9 +15,11 @@
  */
 package com.google.android.exoplayer2.audio;
 
+import android.support.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.C.Encoding;
 import com.google.android.exoplayer2.Format;
+import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.Util;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
@@ -64,7 +66,7 @@ public final class SonicAudioProcessor implements AudioProcessor {
   private int channelCount;
   private int sampleRateHz;
 
-  private Sonic sonic;
+  private @Nullable Sonic sonic;
   private float speed;
   private float pitch;
   private int outputSampleRateHz;
@@ -185,6 +187,7 @@ public final class SonicAudioProcessor implements AudioProcessor {
 
   @Override
   public void queueInput(ByteBuffer inputBuffer) {
+    Assertions.checkState(sonic != null);
     if (inputBuffer.hasRemaining()) {
       ShortBuffer shortBuffer = inputBuffer.asShortBuffer();
       int inputSize = inputBuffer.remaining();
@@ -210,6 +213,7 @@ public final class SonicAudioProcessor implements AudioProcessor {
 
   @Override
   public void queueEndOfStream() {
+    Assertions.checkState(sonic != null);
     sonic.queueEndOfStream();
     inputEnded = true;
   }
@@ -228,7 +232,8 @@ public final class SonicAudioProcessor implements AudioProcessor {
 
   @Override
   public void flush() {
-    sonic = new Sonic(sampleRateHz, channelCount, speed, pitch, outputSampleRateHz);
+    sonic =
+        isActive() ? new Sonic(sampleRateHz, channelCount, speed, pitch, outputSampleRateHz) : null;
     outputBuffer = EMPTY_BUFFER;
     inputBytes = 0;
     outputBytes = 0;
@@ -237,17 +242,19 @@ public final class SonicAudioProcessor implements AudioProcessor {
 
   @Override
   public void reset() {
-    sonic = null;
-    buffer = EMPTY_BUFFER;
-    shortBuffer = buffer.asShortBuffer();
-    outputBuffer = EMPTY_BUFFER;
+    speed = 1f;
+    pitch = 1f;
     channelCount = Format.NO_VALUE;
     sampleRateHz = Format.NO_VALUE;
     outputSampleRateHz = Format.NO_VALUE;
+    buffer = EMPTY_BUFFER;
+    shortBuffer = buffer.asShortBuffer();
+    outputBuffer = EMPTY_BUFFER;
+    pendingOutputSampleRateHz = SAMPLE_RATE_NO_CHANGE;
+    sonic = null;
     inputBytes = 0;
     outputBytes = 0;
     inputEnded = false;
-    pendingOutputSampleRateHz = SAMPLE_RATE_NO_CHANGE;
   }
 
 }
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/audio/TrimmingAudioProcessor.java b/library/core/src/main/java/com/google/android/exoplayer2/audio/TrimmingAudioProcessor.java
index 9ff1c158dd..25db5fc871 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/audio/TrimmingAudioProcessor.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/audio/TrimmingAudioProcessor.java
@@ -22,9 +22,7 @@ import com.google.android.exoplayer2.util.Util;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 
-/**
- * Audio processor for trimming samples from the start/end of data.
- */
+/** Audio processor for trimming samples from the start/end of data. */
 /* package */ final class TrimmingAudioProcessor implements AudioProcessor {
 
   private boolean isActive;
@@ -40,13 +38,13 @@ import java.nio.ByteOrder;
   private int endBufferSize;
   private boolean inputEnded;
 
-  /**
-   * Creates a new audio processor for trimming samples from the start/end of data.
-   */
+  /** Creates a new audio processor for trimming samples from the start/end of data. */
   public TrimmingAudioProcessor() {
     buffer = EMPTY_BUFFER;
     outputBuffer = EMPTY_BUFFER;
     channelCount = Format.NO_VALUE;
+    sampleRateHz = Format.NO_VALUE;
+    endBuffer = new byte[0];
   }
 
   /**
@@ -182,7 +180,7 @@ import java.nio.ByteOrder;
     buffer = EMPTY_BUFFER;
     channelCount = Format.NO_VALUE;
     sampleRateHz = Format.NO_VALUE;
-    endBuffer = null;
+    endBuffer = new byte[0];
   }
 
 }
diff --git a/library/core/src/test/java/com/google/android/exoplayer2/audio/SilenceSkippingAudioProcessorTest.java b/library/core/src/test/java/com/google/android/exoplayer2/audio/SilenceSkippingAudioProcessorTest.java
index 21106e13f4..ab926029f1 100644
--- a/library/core/src/test/java/com/google/android/exoplayer2/audio/SilenceSkippingAudioProcessorTest.java
+++ b/library/core/src/test/java/com/google/android/exoplayer2/audio/SilenceSkippingAudioProcessorTest.java
@@ -68,12 +68,10 @@ public final class SilenceSkippingAudioProcessorTest {
     silenceSkippingAudioProcessor.setEnabled(false);
 
     // When configuring it.
-    boolean reconfigured =
-        silenceSkippingAudioProcessor.configure(
-            TEST_SIGNAL_SAMPLE_RATE_HZ, TEST_SIGNAL_CHANNEL_COUNT, C.ENCODING_PCM_16BIT);
+    silenceSkippingAudioProcessor.configure(
+        TEST_SIGNAL_SAMPLE_RATE_HZ, TEST_SIGNAL_CHANNEL_COUNT, C.ENCODING_PCM_16BIT);
 
     // It's not active.
-    assertThat(reconfigured).isFalse();
     assertThat(silenceSkippingAudioProcessor.isActive()).isFalse();
   }
 
@@ -81,12 +79,10 @@ public final class SilenceSkippingAudioProcessorTest {
   public void testDefaultProcessor_isNotEnabled() throws Exception {
     // Given a processor in its default state.
     // When reconfigured.
-    boolean reconfigured =
-        silenceSkippingAudioProcessor.configure(
-            TEST_SIGNAL_SAMPLE_RATE_HZ, TEST_SIGNAL_CHANNEL_COUNT, C.ENCODING_PCM_16BIT);
+    silenceSkippingAudioProcessor.configure(
+        TEST_SIGNAL_SAMPLE_RATE_HZ, TEST_SIGNAL_CHANNEL_COUNT, C.ENCODING_PCM_16BIT);
 
     // It's not active.
-    assertThat(reconfigured).isFalse();
     assertThat(silenceSkippingAudioProcessor.isActive()).isFalse();
   }
 
@@ -97,7 +93,9 @@ public final class SilenceSkippingAudioProcessorTest {
     boolean reconfigured =
         silenceSkippingAudioProcessor.configure(
             TEST_SIGNAL_SAMPLE_RATE_HZ, TEST_SIGNAL_CHANNEL_COUNT, C.ENCODING_PCM_16BIT);
-    assertThat(reconfigured).isTrue();
+    if (reconfigured) {
+      silenceSkippingAudioProcessor.flush();
+    }
 
     // When reconfiguring it with a different sample rate.
     reconfigured =
@@ -305,6 +303,7 @@ public final class SilenceSkippingAudioProcessorTest {
       InputBufferProvider inputBufferProvider,
       int inputBufferSize)
       throws UnhandledFormatException {
+    processor.flush();
     long totalOutputFrames = 0;
     while (inputBufferProvider.hasRemaining()) {
       ByteBuffer inputBuffer = inputBufferProvider.getNextInputBuffer(inputBufferSize);