Add GVR spatial audio rendering extension.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=148658631

extensions/gvr/src/main/AndroidManifest.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2017 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.
+-->
+<manifest package="com.google.android.exoplayer2.ext.gvr"/>

extensions/gvr/src/main/java/com/google/android/exoplayer2/ext/gvr/GvrBufferProcessor.java

@@ -0,0 +1,170 @@
+/*
+ * Copyright (C) 2017 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.ext.gvr;
+
+import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.Format;
+import com.google.android.exoplayer2.audio.BufferProcessor;
+import com.google.vr.sdk.audio.GvrAudioSurround;
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+
+/**
+ * Buffer processor that uses {@code GvrAudioSurround} to provide binaural rendering of surround
+ * sound and ambisonic soundfields.
+ */
+public final class GvrBufferProcessor implements BufferProcessor {
+
+  private static final int FRAMES_PER_OUTPUT_BUFFER = 1024;
+  private static final int OUTPUT_CHANNEL_COUNT = 2;
+  private static final int OUTPUT_FRAME_SIZE = OUTPUT_CHANNEL_COUNT * 2; // 16-bit stereo output.
+
+  private int sampleRateHz;
+  private int channelCount;
+  private GvrAudioSurround gvrAudioSurround;
+  private ByteBuffer buffer;
+  private boolean inputEnded;
+
+  private float w;
+  private float x;
+  private float y;
+  private float z;
+
+  public GvrBufferProcessor() {
+    // Use the identity for the initial orientation.
+    w = 1f;
+    sampleRateHz = Format.NO_VALUE;
+    channelCount = Format.NO_VALUE;
+  }
+
+  /**
+   * Updates the listener head orientation. May be called on any thread. See
+   * {@code GvrAudioSurround.updateNativeOrientation}.
+   */
+  public synchronized void updateOrientation(float w, float x, float y, float z) {
+    this.w = w;
+    this.x = x;
+    this.y = y;
+    this.z = z;
+    if (gvrAudioSurround != null) {
+      gvrAudioSurround.updateNativeOrientation(w, x, y, z);
+    }
+  }
+
+  @Override
+  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);
+    }
+    if (this.sampleRateHz == sampleRateHz && this.channelCount == channelCount) {
+      return false;
+    }
+    this.sampleRateHz = sampleRateHz;
+    this.channelCount = channelCount;
+    maybeReleaseGvrAudioSurround();
+    int surroundFormat;
+    switch (channelCount) {
+      case 2:
+        surroundFormat = GvrAudioSurround.SurroundFormat.SURROUND_STEREO;
+        break;
+      case 4:
+        surroundFormat = GvrAudioSurround.SurroundFormat.FIRST_ORDER_AMBISONICS;
+        break;
+      case 6:
+        surroundFormat = GvrAudioSurround.SurroundFormat.SURROUND_FIVE_DOT_ONE;
+        break;
+      case 9:
+        surroundFormat = GvrAudioSurround.SurroundFormat.SECOND_ORDER_AMBISONICS;
+        break;
+      case 16:
+        surroundFormat = GvrAudioSurround.SurroundFormat.THIRD_ORDER_AMBISONICS;
+        break;
+      default:
+        throw new UnhandledFormatException(sampleRateHz, channelCount, encoding);
+    }
+    gvrAudioSurround = new GvrAudioSurround(surroundFormat, sampleRateHz, channelCount,
+        FRAMES_PER_OUTPUT_BUFFER);
+    gvrAudioSurround.updateNativeOrientation(w, x, y, z);
+    if (buffer == null) {
+      buffer = ByteBuffer.allocateDirect(FRAMES_PER_OUTPUT_BUFFER * OUTPUT_FRAME_SIZE)
+          .order(ByteOrder.nativeOrder());
+    }
+    return true;
+  }
+
+  @Override
+  public boolean isActive() {
+    return gvrAudioSurround != null;
+  }
+
+  @Override
+  public int getOutputChannelCount() {
+    return OUTPUT_CHANNEL_COUNT;
+  }
+
+  @Override
+  public int getOutputEncoding() {
+    return C.ENCODING_PCM_16BIT;
+  }
+
+  @Override
+  public void queueInput(ByteBuffer input) {
+    int position = input.position();
+    int readBytes = gvrAudioSurround.addInput(input, position, input.limit() - position);
+    input.position(position + readBytes);
+  }
+
+  @Override
+  public void queueEndOfStream() {
+    inputEnded = true;
+    gvrAudioSurround.triggerProcessing();
+  }
+
+  @Override
+  public ByteBuffer getOutput() {
+    int writtenBytes = gvrAudioSurround.getOutput(buffer, 0, buffer.capacity());
+    buffer.position(0).limit(writtenBytes);
+    return buffer;
+  }
+
+  @Override
+  public boolean isEnded() {
+    return inputEnded && gvrAudioSurround.getAvailableOutputSize() == 0;
+  }
+
+  @Override
+  public void flush() {
+    gvrAudioSurround.flush();
+    inputEnded = false;
+  }
+
+  @Override
+  public synchronized void release() {
+    buffer = null;
+    maybeReleaseGvrAudioSurround();
+  }
+
+  private void maybeReleaseGvrAudioSurround() {
+    if (this.gvrAudioSurround != null) {
+      GvrAudioSurround gvrAudioSurround = this.gvrAudioSurround;
+      this.gvrAudioSurround = null;
+      gvrAudioSurround.release();
+    }
+  }
+
+}

settings.gradle

@@ -17,6 +17,7 @@ include ':demo'
 include ':playbacktests'
 include ':extension-ffmpeg'
 include ':extension-flac'
+include ':extension-gvr'
 include ':extension-okhttp'
 include ':extension-opus'
 include ':extension-vp9'
@@ -25,6 +26,7 @@ include ':extension-vp9'
 
 project(':extension-ffmpeg').projectDir = new File(settingsDir, 'extensions/ffmpeg')
 project(':extension-flac').projectDir = new File(settingsDir, 'extensions/flac')
+project(':extension-gvr').projectDir = new File(settingsDir, 'extensions/gvr')
 project(':extension-okhttp').projectDir = new File(settingsDir, 'extensions/okhttp')
 project(':extension-opus').projectDir = new File(settingsDir, 'extensions/opus')
 project(':extension-vp9').projectDir = new File(settingsDir, 'extensions/vp9')