Pass an array of BufferProcessors to the AudioTrack.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=146215966

extensions/ffmpeg/src/main/java/com/google/android/exoplayer2/ext/ffmpeg/FfmpegAudioRenderer.java

@@ -19,8 +19,8 @@ import android.os.Handler;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.ExoPlaybackException;
 import com.google.android.exoplayer2.Format;
-import com.google.android.exoplayer2.audio.AudioCapabilities;
 import com.google.android.exoplayer2.audio.AudioRendererEventListener;
+import com.google.android.exoplayer2.audio.BufferProcessor;
 import com.google.android.exoplayer2.audio.SimpleDecoderAudioRenderer;
 import com.google.android.exoplayer2.drm.ExoMediaCrypto;
 import com.google.android.exoplayer2.util.MimeTypes;
@@ -43,21 +43,12 @@ public final class FfmpegAudioRenderer extends SimpleDecoderAudioRenderer {
    * @param eventHandler A handler to use when delivering events to {@code eventListener}. May be
    *     null if delivery of events is not required.
    * @param eventListener A listener of events. May be null if delivery of events is not required.
-   */
-  public FfmpegAudioRenderer(Handler eventHandler, AudioRendererEventListener eventListener) {
-    super(eventHandler, eventListener);
-  }
-
-  /**
-   * @param eventHandler A handler to use when delivering events to {@code eventListener}. May be
-   *     null if delivery of events is not required.
-   * @param eventListener A listener of events. May be null if delivery of events is not required.
-   * @param audioCapabilities The audio capabilities for playback on this device. May be null if the
-   *     default capabilities (no encoded audio passthrough support) should be assumed.
+   * @param bufferProcessors Optional {@link BufferProcessor}s which will process PCM audio buffers
+   *     before they are output.
    */
   public FfmpegAudioRenderer(Handler eventHandler, AudioRendererEventListener eventListener,
-      AudioCapabilities audioCapabilities) {
-    super(eventHandler, eventListener, audioCapabilities);
+      BufferProcessor... bufferProcessors) {
+    super(eventHandler, eventListener, bufferProcessors);
   }
 
   @Override

extensions/flac/src/main/java/com/google/android/exoplayer2/ext/flac/LibflacAudioRenderer.java

@@ -17,8 +17,8 @@ package com.google.android.exoplayer2.ext.flac;
 
 import android.os.Handler;
 import com.google.android.exoplayer2.Format;
-import com.google.android.exoplayer2.audio.AudioCapabilities;
 import com.google.android.exoplayer2.audio.AudioRendererEventListener;
+import com.google.android.exoplayer2.audio.BufferProcessor;
 import com.google.android.exoplayer2.audio.SimpleDecoderAudioRenderer;
 import com.google.android.exoplayer2.drm.ExoMediaCrypto;
 import com.google.android.exoplayer2.util.MimeTypes;
@@ -38,21 +38,12 @@ public class LibflacAudioRenderer extends SimpleDecoderAudioRenderer {
    * @param eventHandler A handler to use when delivering events to {@code eventListener}. May be
    *     null if delivery of events is not required.
    * @param eventListener A listener of events. May be null if delivery of events is not required.
-   */
-  public LibflacAudioRenderer(Handler eventHandler, AudioRendererEventListener eventListener) {
-    super(eventHandler, eventListener);
-  }
-
-  /**
-   * @param eventHandler A handler to use when delivering events to {@code eventListener}. May be
-   *     null if delivery of events is not required.
-   * @param eventListener A listener of events. May be null if delivery of events is not required.
-   * @param audioCapabilities The audio capabilities for playback on this device. May be null if the
-   *     default capabilities (no encoded audio passthrough support) should be assumed.
+   * @param bufferProcessors Optional {@link BufferProcessor}s which will process PCM audio buffers
+   *     before they are output.
    */
   public LibflacAudioRenderer(Handler eventHandler, AudioRendererEventListener eventListener,
-      AudioCapabilities audioCapabilities) {
-    super(eventHandler, eventListener, audioCapabilities);
+      BufferProcessor... bufferProcessors) {
+    super(eventHandler, eventListener, bufferProcessors);
   }
 
   @Override

extensions/opus/src/main/java/com/google/android/exoplayer2/ext/opus/LibopusAudioRenderer.java

@@ -17,8 +17,8 @@ package com.google.android.exoplayer2.ext.opus;
 
 import android.os.Handler;
 import com.google.android.exoplayer2.Format;
-import com.google.android.exoplayer2.audio.AudioCapabilities;
 import com.google.android.exoplayer2.audio.AudioRendererEventListener;
+import com.google.android.exoplayer2.audio.BufferProcessor;
 import com.google.android.exoplayer2.audio.SimpleDecoderAudioRenderer;
 import com.google.android.exoplayer2.drm.DrmSessionManager;
 import com.google.android.exoplayer2.drm.ExoMediaCrypto;
@@ -40,35 +40,26 @@ public final class LibopusAudioRenderer extends SimpleDecoderAudioRenderer {
    * @param eventHandler A handler to use when delivering events to {@code eventListener}. May be
    *     null if delivery of events is not required.
    * @param eventListener A listener of events. May be null if delivery of events is not required.
-   */
-  public LibopusAudioRenderer(Handler eventHandler, AudioRendererEventListener eventListener) {
-    super(eventHandler, eventListener);
-  }
-
-  /**
-   * @param eventHandler A handler to use when delivering events to {@code eventListener}. May be
-   *     null if delivery of events is not required.
-   * @param eventListener A listener of events. May be null if delivery of events is not required.
-   * @param audioCapabilities The audio capabilities for playback on this device. May be null if the
-   *     default capabilities (no encoded audio passthrough support) should be assumed.
+   * @param bufferProcessors Optional {@link BufferProcessor}s which will process PCM audio buffers
+   *     before they are output.
    */
   public LibopusAudioRenderer(Handler eventHandler, AudioRendererEventListener eventListener,
-      AudioCapabilities audioCapabilities) {
-    super(eventHandler, eventListener, audioCapabilities);
+      BufferProcessor... bufferProcessors) {
+    super(eventHandler, eventListener, bufferProcessors);
   }
 
   /**
    * @param eventHandler A handler to use when delivering events to {@code eventListener}. May be
    *     null if delivery of events is not required.
    * @param eventListener A listener of events. May be null if delivery of events is not required.
-   * @param audioCapabilities The audio capabilities for playback on this device. May be null if the
-   *     default capabilities (no encoded audio passthrough support) should be assumed.
+   * @param bufferProcessors Optional {@link BufferProcessor}s which will process PCM audio
+   *     buffers before they are output.
    */
   public LibopusAudioRenderer(Handler eventHandler, AudioRendererEventListener eventListener,
-      AudioCapabilities audioCapabilities, DrmSessionManager<ExoMediaCrypto> drmSessionManager,
-      boolean playClearSamplesWithoutKeys) {
-    super(eventHandler, eventListener, audioCapabilities, drmSessionManager,
-        playClearSamplesWithoutKeys);
+      DrmSessionManager<ExoMediaCrypto> drmSessionManager, boolean playClearSamplesWithoutKeys,
+      BufferProcessor... bufferProcessors) {
+    super(eventHandler, eventListener, null, drmSessionManager, playClearSamplesWithoutKeys,
+        bufferProcessors);
   }
 
   @Override

library/src/main/java/com/google/android/exoplayer2/SimpleExoPlayer.java

@@ -29,6 +29,7 @@ import android.view.SurfaceView;
 import android.view.TextureView;
 import com.google.android.exoplayer2.audio.AudioCapabilities;
 import com.google.android.exoplayer2.audio.AudioRendererEventListener;
+import com.google.android.exoplayer2.audio.BufferProcessor;
 import com.google.android.exoplayer2.audio.MediaCodecAudioRenderer;
 import com.google.android.exoplayer2.decoder.DecoderCounters;
 import com.google.android.exoplayer2.drm.DrmSessionManager;
@@ -624,7 +625,7 @@ public class SimpleExoPlayer implements ExoPlayer {
     buildVideoRenderers(context, mainHandler, drmSessionManager, extensionRendererMode,
         componentListener, allowedVideoJoiningTimeMs, out);
     buildAudioRenderers(context, mainHandler, drmSessionManager, extensionRendererMode,
-        componentListener, out);
+        componentListener, buildBufferProcessors(), out);
     buildTextRenderers(context, mainHandler, extensionRendererMode, componentListener, out);
     buildMetadataRenderers(context, mainHandler, extensionRendererMode, componentListener, out);
     buildMiscellaneousRenderers(context, mainHandler, extensionRendererMode, out);
@@ -636,7 +637,7 @@ public class SimpleExoPlayer implements ExoPlayer {
    * @param context The {@link Context} associated with the player.
    * @param mainHandler A handler associated with the main thread's looper.
    * @param drmSessionManager An optional {@link DrmSessionManager}. May be null if the player will
-   * not be used for DRM protected playbacks.
+   *     not be used for DRM protected playbacks.
    * @param extensionRendererMode The extension renderer mode.
    * @param eventListener An event listener.
    * @param allowedVideoJoiningTimeMs The maximum duration in milliseconds for which video renderers
@@ -681,17 +682,19 @@ public class SimpleExoPlayer implements ExoPlayer {
    * @param context The {@link Context} associated with the player.
    * @param mainHandler A handler associated with the main thread's looper.
    * @param drmSessionManager An optional {@link DrmSessionManager}. May be null if the player will
-   * not be used for DRM protected playbacks.
+   *     not be used for DRM protected playbacks.
    * @param extensionRendererMode The extension renderer mode.
    * @param eventListener An event listener.
+   * @param bufferProcessors An array of {@link BufferProcessor}s which will process PCM audio
+   *     buffers before they are output. May be empty.
    * @param out An array to which the built renderers should be appended.
    */
   protected void buildAudioRenderers(Context context, Handler mainHandler,
       DrmSessionManager<FrameworkMediaCrypto> drmSessionManager,
       @ExtensionRendererMode int extensionRendererMode, AudioRendererEventListener eventListener,
-      ArrayList<Renderer> out) {
+      BufferProcessor[] bufferProcessors, ArrayList<Renderer> out) {
     out.add(new MediaCodecAudioRenderer(MediaCodecSelector.DEFAULT, drmSessionManager, true,
-        mainHandler, eventListener, AudioCapabilities.getCapabilities(context)));
+        mainHandler, eventListener, AudioCapabilities.getCapabilities(context), bufferProcessors));
 
     if (extensionRendererMode == EXTENSION_RENDERER_MODE_OFF) {
       return;
@@ -705,8 +708,9 @@ public class SimpleExoPlayer implements ExoPlayer {
       Class<?> clazz =
           Class.forName("com.google.android.exoplayer2.ext.opus.LibopusAudioRenderer");
       Constructor<?> constructor = clazz.getConstructor(Handler.class,
-          AudioRendererEventListener.class);
-      Renderer renderer = (Renderer) constructor.newInstance(mainHandler, componentListener);
+          AudioRendererEventListener.class, BufferProcessor[].class);
+      Renderer renderer = (Renderer) constructor.newInstance(mainHandler, componentListener,
+          bufferProcessors);
       out.add(extensionRendererIndex++, renderer);
       Log.i(TAG, "Loaded LibopusAudioRenderer.");
     } catch (ClassNotFoundException e) {
@@ -719,8 +723,9 @@ public class SimpleExoPlayer implements ExoPlayer {
       Class<?> clazz =
           Class.forName("com.google.android.exoplayer2.ext.flac.LibflacAudioRenderer");
       Constructor<?> constructor = clazz.getConstructor(Handler.class,
-          AudioRendererEventListener.class);
-      Renderer renderer = (Renderer) constructor.newInstance(mainHandler, componentListener);
+          AudioRendererEventListener.class, BufferProcessor[].class);
+      Renderer renderer = (Renderer) constructor.newInstance(mainHandler, componentListener,
+          bufferProcessors);
       out.add(extensionRendererIndex++, renderer);
       Log.i(TAG, "Loaded LibflacAudioRenderer.");
     } catch (ClassNotFoundException e) {
@@ -733,8 +738,9 @@ public class SimpleExoPlayer implements ExoPlayer {
       Class<?> clazz =
           Class.forName("com.google.android.exoplayer2.ext.ffmpeg.FfmpegAudioRenderer");
       Constructor<?> constructor = clazz.getConstructor(Handler.class,
-          AudioRendererEventListener.class);
-      Renderer renderer = (Renderer) constructor.newInstance(mainHandler, componentListener);
+          AudioRendererEventListener.class, BufferProcessor[].class);
+      Renderer renderer = (Renderer) constructor.newInstance(mainHandler, componentListener,
+          bufferProcessors);
       out.add(extensionRendererIndex++, renderer);
       Log.i(TAG, "Loaded FfmpegAudioRenderer.");
     } catch (ClassNotFoundException e) {
@@ -787,6 +793,14 @@ public class SimpleExoPlayer implements ExoPlayer {
     // Do nothing.
   }
 
+  /**
+   * Builds an array of {@link BufferProcessor}s which will process PCM audio buffers before they
+   * are output.
+   */
+  protected BufferProcessor[] buildBufferProcessors() {
+    return new BufferProcessor[0];
+  }
+
   // Internal methods.
 
   private void removeSurfaceCallbacks() {

library/src/main/java/com/google/android/exoplayer2/audio/AudioTrack.java

@@ -91,6 +91,21 @@ public final class AudioTrack {
   }
 
   /**
+   * Thrown when a failure occurs configuring the track.
+   */
+  public static final class ConfigurationException extends Exception {
+
+    public ConfigurationException(Throwable cause) {
+      super(cause);
+    }
+
+    public ConfigurationException(String message) {
+      super(message);
+    }
+
+  }
+
+  /**
    * Thrown when a failure occurs initializing an {@link android.media.AudioTrack}.
    */
   public static final class InitializationException extends Exception {
@@ -254,6 +269,7 @@ public final class AudioTrack {
   public static boolean failOnSpuriousAudioTimestamp = false;
 
   private final AudioCapabilities audioCapabilities;
+  private final BufferProcessor[] bufferProcessors;
   private final Listener listener;
   private final ConditionVariable releasingConditionVariable;
   private final long[] playheadOffsets;
@@ -267,12 +283,12 @@ public final class AudioTrack {
   private android.media.AudioTrack audioTrack;
   private int sampleRate;
   private int channelConfig;
-  @C.StreamType
-  private int streamType;
   @C.Encoding
-  private int inputEncoding;
+  private int encoding;
   @C.Encoding
   private int outputEncoding;
+  @C.StreamType
+  private int streamType;
   private boolean passthrough;
   private int pcmFrameSize;
   private int bufferSize;
@@ -303,8 +319,6 @@ public final class AudioTrack {
   private byte[] preV21OutputBuffer;
   private int preV21OutputBufferOffset;
 
-  private BufferProcessor resampler;
-
   private boolean playing;
   private int audioSessionId;
   private boolean tunneling;
@@ -312,11 +326,18 @@ public final class AudioTrack {
   private long lastFeedElapsedRealtimeMs;
 
   /**
-   * @param audioCapabilities The current audio capabilities.
+   * @param audioCapabilities The audio capabilities for playback on this device. May be null if the
+   *     default capabilities (no encoded audio passthrough support) should be assumed.
+   * @param bufferProcessors An array of {@link BufferProcessor}s which will process PCM audio
+   *     buffers before they are output. May be empty.
    * @param listener Listener for audio track events.
    */
-  public AudioTrack(AudioCapabilities audioCapabilities, Listener listener) {
+  public AudioTrack(AudioCapabilities audioCapabilities, BufferProcessor[] bufferProcessors,
+      Listener listener) {
     this.audioCapabilities = audioCapabilities;
+    this.bufferProcessors = new BufferProcessor[bufferProcessors.length + 1];
+    this.bufferProcessors[0] = new ResamplingBufferProcessor();
+    System.arraycopy(bufferProcessors, 0, this.bufferProcessors, 1, bufferProcessors.length);
     this.listener = listener;
     releasingConditionVariable = new ConditionVariable(true);
     if (Util.SDK_INT >= 18) {
@@ -413,9 +434,23 @@ public final class AudioTrack {
    *     {@link C#ENCODING_PCM_32BIT}.
    * @param specifiedBufferSize A specific size for the playback buffer in bytes, or 0 to infer a
    *     suitable buffer size automatically.
+   * @throws ConfigurationException If an error occurs configuring the track.
    */
   public void configure(String mimeType, int channelCount, int sampleRate,
-      @C.PcmEncoding int pcmEncoding, int specifiedBufferSize) {
+      @C.PcmEncoding int pcmEncoding, int specifiedBufferSize) throws ConfigurationException {
+    boolean passthrough = !MimeTypes.AUDIO_RAW.equals(mimeType);
+    @C.Encoding int encoding = passthrough ? getEncodingForMimeType(mimeType) : pcmEncoding;
+    if (!passthrough) {
+      for (BufferProcessor bufferProcessor : bufferProcessors) {
+        try {
+          bufferProcessor.configure(sampleRate, channelCount, encoding);
+        } catch (BufferProcessor.UnhandledFormatException e) {
+          throw new ConfigurationException(e);
+        }
+        encoding = bufferProcessor.getOutputEncoding();
+      }
+    }
+
     int channelConfig;
     switch (channelCount) {
       case 1:
@@ -443,7 +478,7 @@ public final class AudioTrack {
         channelConfig = C.CHANNEL_OUT_7POINT1_SURROUND;
         break;
       default:
-        throw new IllegalArgumentException("Unsupported channel count: " + channelCount);
+        throw new ConfigurationException("Unsupported channel count: " + channelCount);
     }
 
     // Workaround for overly strict channel configuration checks on nVidia Shield.
@@ -461,25 +496,13 @@ public final class AudioTrack {
       }
     }
 
-    boolean passthrough = !MimeTypes.AUDIO_RAW.equals(mimeType);
-
     // Workaround for Nexus Player not reporting support for mono passthrough.
     // (See [Internal: b/34268671].)
     if (Util.SDK_INT <= 25 && "fugu".equals(Util.DEVICE) && passthrough && channelCount == 1) {
       channelConfig = AudioFormat.CHANNEL_OUT_STEREO;
     }
 
-    @C.Encoding int inputEncoding;
-    if (passthrough) {
-      inputEncoding = getEncodingForMimeType(mimeType);
-    } else if (pcmEncoding == C.ENCODING_PCM_8BIT || pcmEncoding == C.ENCODING_PCM_16BIT
-        || pcmEncoding == C.ENCODING_PCM_24BIT || pcmEncoding == C.ENCODING_PCM_32BIT) {
-      inputEncoding = pcmEncoding;
-    } else {
-      throw new IllegalArgumentException("Unsupported PCM encoding: " + pcmEncoding);
-    }
-
-    if (isInitialized() && this.inputEncoding == inputEncoding && this.sampleRate == sampleRate
+    if (isInitialized() && this.encoding == encoding && this.sampleRate == sampleRate
         && this.channelConfig == channelConfig) {
       // We already have an audio track with the correct sample rate, channel config and encoding.
       return;
@@ -487,15 +510,12 @@ public final class AudioTrack {
 
     reset();
 
-    this.inputEncoding = inputEncoding;
+    this.encoding = encoding;
     this.passthrough = passthrough;
     this.sampleRate = sampleRate;
     this.channelConfig = channelConfig;
     pcmFrameSize = 2 * channelCount; // 2 bytes per 16-bit sample * number of channels.
-    outputEncoding = passthrough ? inputEncoding : C.ENCODING_PCM_16BIT;
-
-    resampler = outputEncoding != inputEncoding ? new ResamplingBufferProcessor(inputEncoding)
-        : null;
+    outputEncoding = passthrough ? encoding : C.ENCODING_PCM_16BIT;
 
     if (specifiedBufferSize != 0) {
       bufferSize = specifiedBufferSize;
@@ -684,8 +704,12 @@ public final class AudioTrack {
       }
 
       inputBuffer = buffer;
-      outputBuffer = resampler != null ? resampler.handleBuffer(inputBuffer, outputBuffer)
-          : inputBuffer;
+      if (!passthrough) {
+        for (BufferProcessor bufferProcessor : bufferProcessors) {
+          buffer = bufferProcessor.handleBuffer(buffer);
+        }
+      }
+      outputBuffer = buffer;
       if (Util.SDK_INT < 21) {
         int bytesRemaining = outputBuffer.remaining();
         if (preV21OutputBuffer == null || preV21OutputBuffer.length < bytesRemaining) {
@@ -886,6 +910,9 @@ public final class AudioTrack {
       framesPerEncodedSample = 0;
       inputBuffer = null;
       avSyncHeader = null;
+      for (BufferProcessor bufferProcessor : bufferProcessors) {
+        bufferProcessor.flush();
+      }
       bytesUntilNextAvSync = 0;
       startMediaTimeState = START_NOT_SET;
       latencyUs = 0;
@@ -919,6 +946,9 @@ public final class AudioTrack {
   public void release() {
     reset();
     releaseKeepSessionIdAudioTrack();
+    for (BufferProcessor bufferProcessor : bufferProcessors) {
+      bufferProcessor.release();
+    }
     audioSessionId = C.AUDIO_SESSION_ID_UNSET;
     playing = false;
   }

library/src/main/java/com/google/android/exoplayer2/audio/BufferProcessor.java

@@ -15,23 +15,60 @@
  */
 package com.google.android.exoplayer2.audio;
 
+import com.google.android.exoplayer2.C;
 import java.nio.ByteBuffer;
 
 /**
- * Interface for processors of buffers, for use with {@link AudioTrack}.
+ * Interface for processors of audio buffers.
  */
 public interface BufferProcessor {
 
   /**
-   * Processes the data in the specified input buffer in its entirety. Populates {@code output} with
-   * processed data if is not {@code null} and has sufficient capacity. Otherwise a different buffer
-   * will be populated and returned.
+   * Exception thrown when a processor can't be configured for a given input format.
+   */
+  final class UnhandledFormatException extends Exception {
+
+    public UnhandledFormatException(int sampleRateHz, int channelCount, @C.Encoding int encoding) {
+      super("Unhandled format: " + sampleRateHz + " Hz, " + channelCount + " channels in encoding "
+          + encoding);
+    }
+
+  }
+
+  /**
+   * Configures this processor to take input buffers with the specified 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.
+   * @throws UnhandledFormatException Thrown if the specified format can't be handled as input.
+   */
+  void configure(int sampleRateHz, int channelCount, @C.Encoding int encoding)
+      throws UnhandledFormatException;
+
+  /**
+   * Returns the encoding used in buffers output by this processor.
+   */
+  @C.Encoding
+  int getOutputEncoding();
+
+  /**
+   * Processes the data in the specified input buffer in its entirety.
    *
    * @param input A buffer containing the input data to process.
-   * @param output A buffer into which the output should be written, if its capacity is sufficient.
-   * @return The processed output. Different to {@code output} if null was passed, or if its
-   *     capacity was insufficient.
+   * @return A buffer containing the processed output. This may be the same as the input buffer if
+   *     no processing was required.
+   */
+  ByteBuffer handleBuffer(ByteBuffer input);
+
+  /**
+   * Clears any state in preparation for receiving a new stream of buffers.
+   */
+  void flush();
+
+  /**
+   * Releases any resources associated with this instance.
    */
-  ByteBuffer handleBuffer(ByteBuffer input, ByteBuffer output);
+  void release();
 
 }

library/src/main/java/com/google/android/exoplayer2/audio/MediaCodecAudioRenderer.java

@@ -121,13 +121,16 @@ public class MediaCodecAudioRenderer extends MediaCodecRenderer implements Media
    * @param eventListener A listener of events. May be null if delivery of events is not required.
    * @param audioCapabilities The audio capabilities for playback on this device. May be null if the
    *     default capabilities (no encoded audio passthrough support) should be assumed.
+   * @param bufferProcessors Optional {@link BufferProcessor}s which will process PCM audio buffers
+   *     before they are output.
    */
   public MediaCodecAudioRenderer(MediaCodecSelector mediaCodecSelector,
       DrmSessionManager<FrameworkMediaCrypto> drmSessionManager,
       boolean playClearSamplesWithoutKeys, Handler eventHandler,
-      AudioRendererEventListener eventListener, AudioCapabilities audioCapabilities) {
+      AudioRendererEventListener eventListener, AudioCapabilities audioCapabilities,
+      BufferProcessor... bufferProcessors) {
     super(C.TRACK_TYPE_AUDIO, mediaCodecSelector, drmSessionManager, playClearSamplesWithoutKeys);
-    audioTrack = new AudioTrack(audioCapabilities, new AudioTrackListener());
+    audioTrack = new AudioTrack(audioCapabilities, bufferProcessors, new AudioTrackListener());
     eventDispatcher = new EventDispatcher(eventHandler, eventListener);
   }
 
@@ -219,14 +222,19 @@ public class MediaCodecAudioRenderer extends MediaCodecRenderer implements Media
   }
 
   @Override
-  protected void onOutputFormatChanged(MediaCodec codec, MediaFormat outputFormat) {
+  protected void onOutputFormatChanged(MediaCodec codec, MediaFormat outputFormat)
+      throws ExoPlaybackException {
     boolean passthrough = passthroughMediaFormat != null;
     String mimeType = passthrough ? passthroughMediaFormat.getString(MediaFormat.KEY_MIME)
         : MimeTypes.AUDIO_RAW;
     MediaFormat format = passthrough ? passthroughMediaFormat : outputFormat;
     int channelCount = format.getInteger(MediaFormat.KEY_CHANNEL_COUNT);
     int sampleRate = format.getInteger(MediaFormat.KEY_SAMPLE_RATE);
-    audioTrack.configure(mimeType, channelCount, sampleRate, pcmEncoding, 0);
+    try {
+      audioTrack.configure(mimeType, channelCount, sampleRate, pcmEncoding, 0);
+    } catch (AudioTrack.ConfigurationException e) {
+      throw ExoPlaybackException.createForRenderer(e, getIndex());
+    }
   }
 
   /**

library/src/main/java/com/google/android/exoplayer2/audio/ResamplingBufferProcessor.java

@@ -21,35 +21,47 @@ import com.google.android.exoplayer2.util.Assertions;
 import java.nio.ByteBuffer;
 
 /**
- * A {@link BufferProcessor} that converts PCM input buffers from a specified input bit depth to
- * {@link C#ENCODING_PCM_16BIT} in preparation for writing to an {@link android.media.AudioTrack}.
+ * A {@link BufferProcessor} that outputs buffers in {@link C#ENCODING_PCM_16BIT}.
  */
 /* package */ final class ResamplingBufferProcessor implements BufferProcessor {
 
   @C.PcmEncoding
-  private final int inputEncoding;
+  private int encoding;
+  private ByteBuffer outputBuffer;
 
-  /**
-   * Creates a new buffer processor for resampling input in the specified encoding.
-   *
-   * @param inputEncoding The PCM encoding of input buffers.
-   * @throws IllegalArgumentException Thrown if the input encoding is not PCM or its bit depth is
-   *     not 8, 24 or 32-bits.
-   */
-  public ResamplingBufferProcessor(@C.PcmEncoding int inputEncoding) {
-    Assertions.checkArgument(inputEncoding == C.ENCODING_PCM_8BIT
-        || inputEncoding == C.ENCODING_PCM_24BIT || inputEncoding == C.ENCODING_PCM_32BIT);
-    this.inputEncoding = inputEncoding;
+  public ResamplingBufferProcessor() {
+    encoding = C.ENCODING_INVALID;
   }
 
   @Override
-  public ByteBuffer handleBuffer(ByteBuffer input, ByteBuffer output) {
-    int offset = input.position();
-    int limit = input.limit();
-    int size = limit - offset;
+  public void configure(int sampleRateHz, int channelCount, @C.Encoding int encoding)
+      throws UnhandledFormatException {
+    if (encoding != C.ENCODING_PCM_8BIT && encoding != C.ENCODING_PCM_16BIT
+        && encoding != C.ENCODING_PCM_24BIT && encoding != C.ENCODING_PCM_32BIT) {
+      throw new UnhandledFormatException(sampleRateHz, channelCount, encoding);
+    }
+    if (encoding == C.ENCODING_PCM_16BIT) {
+      outputBuffer = null;
+    }
+    this.encoding = encoding;
+  }
+
+  @Override
+  public int getOutputEncoding() {
+    return C.ENCODING_PCM_16BIT;
+  }
+
+  @Override
+  public ByteBuffer handleBuffer(ByteBuffer buffer) {
+    int position = buffer.position();
+    int limit = buffer.limit();
+    int size = limit - position;
 
     int resampledSize;
-    switch (inputEncoding) {
+    switch (encoding) {
+      case C.ENCODING_PCM_16BIT:
+        // No processing required.
+        return buffer;
       case C.ENCODING_PCM_8BIT:
         resampledSize = size * 2;
         break;
@@ -59,7 +71,6 @@ import java.nio.ByteBuffer;
       case C.ENCODING_PCM_32BIT:
         resampledSize = size / 2;
         break;
-      case C.ENCODING_PCM_16BIT:
       case C.ENCODING_INVALID:
       case Format.NO_VALUE:
       default:
@@ -67,34 +78,34 @@ import java.nio.ByteBuffer;
         throw new IllegalStateException();
     }
 
-    ByteBuffer resampledBuffer = output;
-    if (resampledBuffer == null || resampledBuffer.capacity() < resampledSize) {
-      resampledBuffer = ByteBuffer.allocateDirect(resampledSize);
+    if (outputBuffer == null || outputBuffer.capacity() < resampledSize) {
+      outputBuffer = ByteBuffer.allocateDirect(resampledSize).order(buffer.order());
+    } else {
+      Assertions.checkState(!outputBuffer.hasRemaining());
+      outputBuffer.clear();
     }
-    resampledBuffer.position(0);
-    resampledBuffer.limit(resampledSize);
 
     // Samples are little endian.
-    switch (inputEncoding) {
+    switch (encoding) {
       case C.ENCODING_PCM_8BIT:
         // 8->16 bit resampling. Shift each byte from [0, 256) to [-128, 128) and scale up.
-        for (int i = offset; i < limit; i++) {
-          resampledBuffer.put((byte) 0);
-          resampledBuffer.put((byte) ((input.get(i) & 0xFF) - 128));
+        for (int i = position; i < limit; i++) {
+          outputBuffer.put((byte) 0);
+          outputBuffer.put((byte) ((buffer.get(i) & 0xFF) - 128));
         }
         break;
       case C.ENCODING_PCM_24BIT:
         // 24->16 bit resampling. Drop the least significant byte.
-        for (int i = offset; i < limit; i += 3) {
-          resampledBuffer.put(input.get(i + 1));
-          resampledBuffer.put(input.get(i + 2));
+        for (int i = position; i < limit; i += 3) {
+          outputBuffer.put(buffer.get(i + 1));
+          outputBuffer.put(buffer.get(i + 2));
         }
         break;
       case C.ENCODING_PCM_32BIT:
         // 32->16 bit resampling. Drop the two least significant bytes.
-        for (int i = offset; i < limit; i += 4) {
-          resampledBuffer.put(input.get(i + 2));
-          resampledBuffer.put(input.get(i + 3));
+        for (int i = position; i < limit; i += 4) {
+          outputBuffer.put(buffer.get(i + 2));
+          outputBuffer.put(buffer.get(i + 3));
         }
         break;
       case C.ENCODING_PCM_16BIT:
@@ -105,8 +116,18 @@ import java.nio.ByteBuffer;
         throw new IllegalStateException();
     }
 
-    resampledBuffer.position(0);
-    return resampledBuffer;
+    outputBuffer.flip();
+    return outputBuffer;
+  }
+
+  @Override
+  public void flush() {
+    // Do nothing.
+  }
+
+  @Override
+  public void release() {
+    outputBuffer = null;
   }
 
 }

library/src/main/java/com/google/android/exoplayer2/audio/SimpleDecoderAudioRenderer.java

@@ -102,10 +102,12 @@ public abstract class SimpleDecoderAudioRenderer extends BaseRenderer implements
    * @param eventHandler A handler to use when delivering events to {@code eventListener}. May be
    *     null if delivery of events is not required.
    * @param eventListener A listener of events. May be null if delivery of events is not required.
+   * @param bufferProcessors Optional {@link BufferProcessor}s which will process PCM audio buffers
+   *     before they are output.
    */
   public SimpleDecoderAudioRenderer(Handler eventHandler,
-      AudioRendererEventListener eventListener) {
-    this(eventHandler, eventListener, null);
+      AudioRendererEventListener eventListener, BufferProcessor... bufferProcessors) {
+    this(eventHandler, eventListener, null, null, false, bufferProcessors);
   }
 
   /**
@@ -133,13 +135,16 @@ public abstract class SimpleDecoderAudioRenderer extends BaseRenderer implements
    *     begin in parallel with key acquisition. This parameter specifies whether the renderer is
    *     permitted to play clear regions of encrypted media files before {@code drmSessionManager}
    *     has obtained the keys necessary to decrypt encrypted regions of the media.
+   * @param bufferProcessors Optional {@link BufferProcessor}s which will process PCM audio
+   *     buffers before they are output.
    */
   public SimpleDecoderAudioRenderer(Handler eventHandler,
       AudioRendererEventListener eventListener, AudioCapabilities audioCapabilities,
-      DrmSessionManager<ExoMediaCrypto> drmSessionManager, boolean playClearSamplesWithoutKeys) {
+      DrmSessionManager<ExoMediaCrypto> drmSessionManager, boolean playClearSamplesWithoutKeys,
+      BufferProcessor... bufferProcessors) {
     super(C.TRACK_TYPE_AUDIO);
     eventDispatcher = new EventDispatcher(eventHandler, eventListener);
-    audioTrack = new AudioTrack(audioCapabilities, new AudioTrackListener());
+    audioTrack = new AudioTrack(audioCapabilities, bufferProcessors, new AudioTrackListener());
     this.drmSessionManager = drmSessionManager;
     formatHolder = new FormatHolder();
     this.playClearSamplesWithoutKeys = playClearSamplesWithoutKeys;
@@ -193,8 +198,8 @@ public abstract class SimpleDecoderAudioRenderer extends BaseRenderer implements
         while (drainOutputBuffer()) {}
         while (feedInputBuffer()) {}
         TraceUtil.endSection();
-      } catch (AudioTrack.InitializationException | AudioTrack.WriteException
-          | AudioDecoderException e) {
+      } catch (AudioDecoderException | AudioTrack.ConfigurationException
+          | AudioTrack.InitializationException | AudioTrack.WriteException e) {
         throw ExoPlaybackException.createForRenderer(e, getIndex());
       }
       decoderCounters.ensureUpdated();
@@ -255,7 +260,8 @@ public abstract class SimpleDecoderAudioRenderer extends BaseRenderer implements
   }
 
   private boolean drainOutputBuffer() throws ExoPlaybackException, AudioDecoderException,
-      AudioTrack.InitializationException, AudioTrack.WriteException {
+      AudioTrack.ConfigurationException, AudioTrack.InitializationException,
+      AudioTrack.WriteException {
     if (outputBuffer == null) {
       outputBuffer = decoder.dequeueOutputBuffer();
       if (outputBuffer == null) {

library/src/main/java/com/google/android/exoplayer2/mediacodec/MediaCodecRenderer.java

@@ -779,8 +779,10 @@ public abstract class MediaCodecRenderer extends BaseRenderer {
    *
    * @param codec The {@link MediaCodec} instance.
    * @param outputFormat The new output format.
+   * @throws ExoPlaybackException Thrown if an error occurs handling the new output format.
    */
-  protected void onOutputFormatChanged(MediaCodec codec, MediaFormat outputFormat) {
+  protected void onOutputFormatChanged(MediaCodec codec, MediaFormat outputFormat)
+      throws ExoPlaybackException {
     // Do nothing.
   }
 
@@ -918,7 +920,7 @@ public abstract class MediaCodecRenderer extends BaseRenderer {
   /**
    * Processes a new output format.
    */
-  private void processOutputFormat() {
+  private void processOutputFormat() throws ExoPlaybackException {
     MediaFormat format = codec.getOutputFormat();
     if (codecNeedsAdaptationWorkaround
         && format.getInteger(MediaFormat.KEY_WIDTH) == ADAPTATION_WORKAROUND_SLICE_WIDTH_HEIGHT