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74 lines
2.6 KiB
74 lines
2.6 KiB
4 months ago
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/*
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* Copyright 2021 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#include <memory>
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#include <vector>
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#include "array2d.h"
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namespace android {
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template <typename Torig, typename Tdct>
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class FastDCT {
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public:
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explicit FastDCT(int block_size);
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void ForwardTransform1D(const std::vector<Torig> &v_in, std::vector<Tdct> *v_out) const;
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void ReverseTransform1D(const std::vector<Tdct> &v_in, std::vector<Torig> *v_out) const;
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void ForwardTransform2D(const Array2D<Torig> &m_in, Array2D<Tdct> *m_out) const;
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void ReverseTransform2D(const Array2D<Tdct> &m_in, Array2D<Torig> *m_out) const;
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int block_size() const { return block_size_; }
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double intermediate_scale_factor() const { return intermediate_scale_factor_; }
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void set_intermediate_scale_factor(double val) { intermediate_scale_factor_ = val; }
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private:
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// Dimensionality of input/output space for 1D transform.
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const int block_size_;
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// DCT coefficients will be scaled by this factor during the forward
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// transform, then divided by this factor during the reverse transform.
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double intermediate_scale_factor_;
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// Scaling factors for making transform orthonormal.
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const double orth_scale_factor_;
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const double sqrt_orth_scale_factor_;
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// Square root of one-half gets used a lot so define it as a constant.
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const double sqrt_one_half_;
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// Array for passing data into and out of external C ddct2d routine.
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std::unique_ptr<double *[]> ddct2d_in_out_ptr_array_;
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// Above pointer array will point into this contiguous block.
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std::unique_ptr<double[]> contiguous_double_array_;
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// Table of cosine and sine values used by external C ddct routine.
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std::unique_ptr<double[]> cos_sin_table_;
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// Array used for passing data into and out of ddct.
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std::unique_ptr<double[]> ddct_in_out_;
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// Scratch workspace for use by ddct2d.
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std::unique_ptr<double[]> t_workspace_;
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// Array used to compute the bit-reversal patterns in ddct.
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std::unique_ptr<int[]> bit_reversal_workspace_;
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};
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} // namespace android
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