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diff --git a/src/3rdparty/resonance-audio/resonance_audio/ambisonics/hoa_rotator.h b/src/3rdparty/resonance-audio/resonance_audio/ambisonics/hoa_rotator.h
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+/*
+Copyright 2018 Google Inc. All Rights Reserved.
+
+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.
+*/
+
+#ifndef RESONANCE_AUDIO_AMBISONICS_HOA_ROTATOR_H_
+#define RESONANCE_AUDIO_AMBISONICS_HOA_ROTATOR_H_
+
+#include <vector>
+
+#include "Eigen/Dense"
+#include "base/audio_buffer.h"
+#include "base/misc_math.h"
+
+namespace vraudio {
+
+// Rotator for higher order ambisonic sound fields. It supports ACN channel
+// ordering and SN3D normalization (AmbiX).
+class HoaRotator {
+ public:
+  // Constructs a sound field rotator of an arbitrary ambisonic order.
+  //
+  // @param ambisonic_order Order of ambisonic sound field.
+  explicit HoaRotator(int ambisonic_order);
+
+  // Performs a smooth inplace rotation of a sound field buffer from
+  // |current_rotation_| to |target_rotation|.
+  //
+  // @param target_rotation Target rotation to be applied to the input buffer.
+  // @param input Higher order sound field input buffer to be rotated.
+  // @param output Pointer to output buffer.
+  // @return True if rotation has been applied.
+  bool Process(const WorldRotation& target_rotation, const AudioBuffer& input,
+               AudioBuffer* output);
+
+ private:
+  // Updates the rotation matrix with using supplied WorldRotation.
+  //
+  // @param rotation World rotation.
+  void UpdateRotationMatrix(const WorldRotation& rotation);
+
+  // Order of the ambisonic sound field handled by the rotator.
+  const int ambisonic_order_;
+
+  // Current rotation which is used in the interpolation process in order to
+  // compute new rotation matrix. Initialized with an identity rotation.
+  WorldRotation current_rotation_;
+
+  // Spherical harmonics rotation sub-matrices for each order.
+  std::vector<Eigen::MatrixXf> rotation_matrices_;
+
+  // Final spherical harmonics rotation matrix.
+  Eigen::MatrixXf rotation_matrix_;
+};
+
+}  // namespace vraudio
+
+#endif  // RESONANCE_AUDIO_AMBISONICS_HOA_ROTATOR_H_