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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_
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