| 1 | /* |
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| 2 | Copyright 2018 Google Inc. All Rights Reserved. |
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| 3 | |
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| 4 | Licensed under the Apache License, Version 2.0 (the "License"); |
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| 5 | you may not use this file except in compliance with the License. |
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| 6 | You may obtain a copy of the License at |
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| 7 | |
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| 8 | http://www.apache.org/licenses/LICENSE-2.0 |
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| 9 | |
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| 10 | Unless required by applicable law or agreed to in writing, software |
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| 11 | distributed under the License is distributed on an "AS-IS" BASIS, |
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| 12 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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| 13 | See the License for the specific language governing permissions and |
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| 14 | limitations under the License. |
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| 15 | */ |
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| 16 | |
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| 17 | #ifndef RESONANCE_AUDIO_AMBISONICS_HOA_ROTATOR_H_ |
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| 18 | #define RESONANCE_AUDIO_AMBISONICS_HOA_ROTATOR_H_ |
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| 19 | |
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| 20 | #include <vector> |
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| 21 | |
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| 22 | #include "Eigen/Dense" |
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| 23 | #include "base/audio_buffer.h" |
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| 24 | #include "base/misc_math.h" |
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| 25 | |
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| 26 | namespace vraudio { |
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| 27 | |
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| 28 | // Rotator for higher order ambisonic sound fields. It supports ACN channel |
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| 29 | // ordering and SN3D normalization (AmbiX). |
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| 30 | class HoaRotator { |
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| 31 | public: |
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| 32 | // Constructs a sound field rotator of an arbitrary ambisonic order. |
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| 33 | // |
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| 34 | // @param ambisonic_order Order of ambisonic sound field. |
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| 35 | explicit HoaRotator(int ambisonic_order); |
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| 36 | |
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| 37 | // Performs a smooth inplace rotation of a sound field buffer from |
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| 38 | // |current_rotation_| to |target_rotation|. |
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| 39 | // |
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| 40 | // @param target_rotation Target rotation to be applied to the input buffer. |
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| 41 | // @param input Higher order sound field input buffer to be rotated. |
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| 42 | // @param output Pointer to output buffer. |
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| 43 | // @return True if rotation has been applied. |
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| 44 | bool Process(const WorldRotation& target_rotation, const AudioBuffer& input, |
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| 45 | AudioBuffer* output); |
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| 46 | |
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| 47 | private: |
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| 48 | // Updates the rotation matrix with using supplied WorldRotation. |
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| 49 | // |
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| 50 | // @param rotation World rotation. |
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| 51 | void UpdateRotationMatrix(const WorldRotation& rotation); |
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| 52 | |
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| 53 | // Order of the ambisonic sound field handled by the rotator. |
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| 54 | const int ambisonic_order_; |
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| 55 | |
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| 56 | // Current rotation which is used in the interpolation process in order to |
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| 57 | // compute new rotation matrix. Initialized with an identity rotation. |
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| 58 | WorldRotation current_rotation_; |
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| 59 | |
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| 60 | // Spherical harmonics rotation sub-matrices for each order. |
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| 61 | std::vector<Eigen::MatrixXf> rotation_matrices_; |
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| 62 | |
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| 63 | // Final spherical harmonics rotation matrix. |
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| 64 | Eigen::MatrixXf rotation_matrix_; |
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| 65 | }; |
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| 66 | |
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| 67 | } // namespace vraudio |
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| 68 | |
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| 69 | #endif // RESONANCE_AUDIO_AMBISONICS_HOA_ROTATOR_H_ |
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| 70 | |
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