Add support for setting auxiliary audio effects

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=208611493

RELEASENOTES.md

@@ -32,6 +32,7 @@
   * Increase `AudioTrack` buffer sizes to the theoretical maximum required for
     each encoding for passthrough playbacks
     ([#3803](https://github.com/google/ExoPlayer/issues/3803)).
+  * Add support for attaching auxiliary audio effects to the `AudioTrack`.
 * Allow apps to pass a `CacheKeyFactory` for setting custom cache keys when
   creating a `CacheDataSource`.
 * Turned on Java 8 compiler support for the ExoPlayer library. Apps that depend

library/core/src/main/java/com/google/android/exoplayer2/C.java

@@ -24,6 +24,7 @@ import android.media.MediaFormat;
 import android.support.annotation.IntDef;
 import android.view.Surface;
 import com.google.android.exoplayer2.PlayerMessage.Target;
+import com.google.android.exoplayer2.audio.AuxEffectInfo;
 import com.google.android.exoplayer2.util.Util;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
@@ -725,6 +726,13 @@ public final class C {
    */
   public static final int MSG_SET_SCALING_MODE = 4;
 
+  /**
+   * A type of a message that can be passed to an audio {@link Renderer} via {@link
+   * ExoPlayer#createMessage(Target)}. The message payload should be an {@link AuxEffectInfo}
+   * instance representing an auxiliary audio effect for the underlying audio track.
+   */
+  public static final int MSG_SET_AUX_EFFECT_INFO = 5;
+
   /**
    * Applications or extensions may define custom {@code MSG_*} constants that can be passed to
    * {@link Renderer}s. These custom constants must be greater than or equal to this value.

library/core/src/main/java/com/google/android/exoplayer2/Player.java

@@ -24,6 +24,7 @@ import android.view.SurfaceView;
 import android.view.TextureView;
 import com.google.android.exoplayer2.audio.AudioAttributes;
 import com.google.android.exoplayer2.audio.AudioListener;
+import com.google.android.exoplayer2.audio.AuxEffectInfo;
 import com.google.android.exoplayer2.source.TrackGroupArray;
 import com.google.android.exoplayer2.text.TextOutput;
 import com.google.android.exoplayer2.trackselection.TrackSelectionArray;
@@ -119,6 +120,12 @@ public interface Player {
     /** Returns the audio session identifier, or {@link C#AUDIO_SESSION_ID_UNSET} if not set. */
     int getAudioSessionId();
 
+    /** Sets information on an auxiliary audio effect to attach to the underlying audio track. */
+    void setAuxEffectInfo(AuxEffectInfo auxEffectInfo);
+
+    /** Detaches any previously attached auxiliary audio effect from the underlying audio track. */
+    void clearAuxEffectInfo();
+
     /**
      * Sets the audio volume, with 0 being silence and 1 being unity gain.
      *

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

@@ -35,6 +35,7 @@ import com.google.android.exoplayer2.audio.AudioAttributes;
 import com.google.android.exoplayer2.audio.AudioFocusManager;
 import com.google.android.exoplayer2.audio.AudioListener;
 import com.google.android.exoplayer2.audio.AudioRendererEventListener;
+import com.google.android.exoplayer2.audio.AuxEffectInfo;
 import com.google.android.exoplayer2.decoder.DecoderCounters;
 import com.google.android.exoplayer2.drm.DefaultDrmSessionManager;
 import com.google.android.exoplayer2.drm.DrmSessionManager;
@@ -450,6 +451,24 @@ public class SimpleExoPlayer
     return audioSessionId;
   }
 
+  @Override
+  public void setAuxEffectInfo(AuxEffectInfo auxEffectInfo) {
+    for (Renderer renderer : renderers) {
+      if (renderer.getTrackType() == C.TRACK_TYPE_AUDIO) {
+        player
+            .createMessage(renderer)
+            .setType(C.MSG_SET_AUX_EFFECT_INFO)
+            .setPayload(auxEffectInfo)
+            .send();
+      }
+    }
+  }
+
+  @Override
+  public void clearAuxEffectInfo() {
+    setAuxEffectInfo(new AuxEffectInfo(AuxEffectInfo.NO_AUX_EFFECT_ID, /* sendLevel= */ 0f));
+  }
+
   @Override
   public void setVolume(float audioVolume) {
     audioVolume = Util.constrainValue(audioVolume, /* min= */ 0, /* max= */ 1);

library/core/src/main/java/com/google/android/exoplayer2/audio/AudioSink.java

@@ -283,11 +283,12 @@ public interface AudioSink {
    */
   void setAudioAttributes(AudioAttributes audioAttributes);
 
-  /**
-   * Sets the audio session id.
-   */
+  /** Sets the audio session id. */
   void setAudioSessionId(int audioSessionId);
 
+  /** Sets the auxiliary effect. */
+  void setAuxEffectInfo(AuxEffectInfo auxEffectInfo);
+
   /**
    * Enables tunneling, if possible. The sink is reset if tunneling was previously disabled or if
    * the audio session id has changed. Enabling tunneling is only possible if the sink is based on a

library/core/src/main/java/com/google/android/exoplayer2/audio/AuxEffectInfo.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.audio;
+
+import android.media.AudioTrack;
+import android.media.audiofx.AudioEffect;
+import android.support.annotation.Nullable;
+
+/**
+ * Represents auxiliary effect information, which can be used to attach an auxiliary effect to an
+ * underlying {@link AudioTrack}.
+ *
+ * <p>Auxiliary effects can only be applied if the application has the {@code
+ * android.permission.MODIFY_AUDIO_SETTINGS} permission. Apps are responsible for retaining the
+ * associated audio effect instance and releasing it when it's no longer needed. See the
+ * documentation of {@link AudioEffect} for more information.
+ */
+public final class AuxEffectInfo {
+
+  /** Value for {@link #effectId} representing no auxiliary effect. */
+  public static final int NO_AUX_EFFECT_ID = 0;
+
+  /**
+   * The identifier of the effect, or {@link #NO_AUX_EFFECT_ID} if there is no effect.
+   *
+   * @see android.media.AudioTrack#attachAuxEffect(int)
+   */
+  public final int effectId;
+  /**
+   * The send level for the effect.
+   *
+   * @see android.media.AudioTrack#setAuxEffectSendLevel(float)
+   */
+  public final float sendLevel;
+
+  /**
+   * Creates an instance with the given effect identifier and send level.
+   *
+   * @param effectId The effect identifier. This is the value returned by {@link
+   *     AudioEffect#getId()} on the effect, or {@value NO_AUX_EFFECT_ID} which represents no
+   *     effect. This value is passed to {@link AudioTrack#attachAuxEffect(int)} on the underlying
+   *     audio track.
+   * @param sendLevel The send level for the effect, where 0 represents no effect and a value of 1
+   *     is full send. If {@code effectId} is not {@value #NO_AUX_EFFECT_ID}, this value is passed
+   *     to {@link AudioTrack#setAuxEffectSendLevel(float)} on the underlying audio track.
+   */
+  public AuxEffectInfo(int effectId, float sendLevel) {
+    this.effectId = effectId;
+    this.sendLevel = sendLevel;
+  }
+
+  @Override
+  public boolean equals(@Nullable Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    AuxEffectInfo auxEffectInfo = (AuxEffectInfo) o;
+    return effectId == auxEffectInfo.effectId
+        && Float.compare(auxEffectInfo.sendLevel, sendLevel) == 0;
+  }
+
+  @Override
+  public int hashCode() {
+    int result = 17;
+    result = 31 * result + effectId;
+    result = 31 * result + Float.floatToIntBits(sendLevel);
+    return result;
+  }
+}

library/core/src/main/java/com/google/android/exoplayer2/audio/DefaultAudioSink.java

@@ -280,6 +280,7 @@ public final class DefaultAudioSink implements AudioSink {
 
   private boolean playing;
   private int audioSessionId;
+  private AuxEffectInfo auxEffectInfo;
   private boolean tunneling;
   private long lastFeedElapsedRealtimeMs;
 
@@ -356,6 +357,7 @@ public final class DefaultAudioSink implements AudioSink {
     startMediaTimeState = START_NOT_SET;
     audioAttributes = AudioAttributes.DEFAULT;
     audioSessionId = C.AUDIO_SESSION_ID_UNSET;
+    auxEffectInfo = new AuxEffectInfo(AuxEffectInfo.NO_AUX_EFFECT_ID, 0f);
     playbackParameters = PlaybackParameters.DEFAULT;
     drainingAudioProcessorIndex = C.INDEX_UNSET;
     activeAudioProcessors = new AudioProcessor[0];
@@ -547,6 +549,11 @@ public final class DefaultAudioSink implements AudioSink {
     audioTrackPositionTracker.setAudioTrack(
         audioTrack, outputEncoding, outputPcmFrameSize, bufferSize);
     setVolumeInternal();
+
+    if (auxEffectInfo.effectId != AuxEffectInfo.NO_AUX_EFFECT_ID) {
+      audioTrack.attachAuxEffect(auxEffectInfo.effectId);
+      audioTrack.setAuxEffectSendLevel(auxEffectInfo.sendLevel);
+    }
   }
 
   @Override
@@ -867,6 +874,24 @@ public final class DefaultAudioSink implements AudioSink {
     }
   }
 
+  @Override
+  public void setAuxEffectInfo(AuxEffectInfo auxEffectInfo) {
+    if (this.auxEffectInfo.equals(auxEffectInfo)) {
+      return;
+    }
+    int effectId = auxEffectInfo.effectId;
+    float sendLevel = auxEffectInfo.sendLevel;
+    if (audioTrack != null) {
+      if (this.auxEffectInfo.effectId != effectId) {
+        audioTrack.attachAuxEffect(effectId);
+      }
+      if (effectId != AuxEffectInfo.NO_AUX_EFFECT_ID) {
+        audioTrack.setAuxEffectSendLevel(sendLevel);
+      }
+    }
+    this.auxEffectInfo = auxEffectInfo;
+  }
+
   @Override
   public void enableTunnelingV21(int tunnelingAudioSessionId) {
     Assertions.checkState(Util.SDK_INT >= 21);

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

@@ -60,6 +60,9 @@ import java.util.List;
  *   <li>Message with type {@link C#MSG_SET_AUDIO_ATTRIBUTES} to set the audio attributes. The
  *       message payload should be an {@link com.google.android.exoplayer2.audio.AudioAttributes}
  *       instance that will configure the underlying audio track.
+ *   <li>Message with type {@link C#MSG_SET_AUX_EFFECT_INFO} to set the auxiliary effect. The
+ *       message payload should be an {@link AuxEffectInfo} instance that will configure the
+ *       underlying audio track.
  * </ul>
  */
 @TargetApi(16)
@@ -583,6 +586,10 @@ public class MediaCodecAudioRenderer extends MediaCodecRenderer implements Media
         AudioAttributes audioAttributes = (AudioAttributes) message;
         audioSink.setAudioAttributes(audioAttributes);
         break;
+      case C.MSG_SET_AUX_EFFECT_INFO:
+        AuxEffectInfo auxEffectInfo = (AuxEffectInfo) message;
+        audioSink.setAuxEffectInfo(auxEffectInfo);
+        break;
       default:
         super.handleMessage(messageType, message);
         break;

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

@@ -58,6 +58,9 @@ import java.lang.annotation.RetentionPolicy;
  *   <li>Message with type {@link C#MSG_SET_AUDIO_ATTRIBUTES} to set the audio attributes. The
  *       message payload should be an {@link com.google.android.exoplayer2.audio.AudioAttributes}
  *       instance that will configure the underlying audio track.
+ *   <li>Message with type {@link C#MSG_SET_AUX_EFFECT_INFO} to set the auxiliary effect. The
+ *       message payload should be an {@link AuxEffectInfo} instance that will configure the
+ *       underlying audio track.
  * </ul>
  */
 public abstract class SimpleDecoderAudioRenderer extends BaseRenderer implements MediaClock {
@@ -590,6 +593,10 @@ public abstract class SimpleDecoderAudioRenderer extends BaseRenderer implements
         AudioAttributes audioAttributes = (AudioAttributes) message;
         audioSink.setAudioAttributes(audioAttributes);
         break;
+      case C.MSG_SET_AUX_EFFECT_INFO:
+        AuxEffectInfo auxEffectInfo = (AuxEffectInfo) message;
+        audioSink.setAuxEffectInfo(auxEffectInfo);
+        break;
       default:
         super.handleMessage(messageType, message);
         break;