63 lines
1.9 KiB
C++
63 lines
1.9 KiB
C++
/*
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* fold.h
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* Copyright (c) 2025 Christopher Herb
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#pragma once
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#include <cmath>
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namespace trnr {
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constexpr float A_LAW_A = 87.6f;
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inline float alaw_encode(float input)
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{
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float sign = (input >= 0.0f) ? 1.0f : -1.0f;
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float abs_sample = std::fabs(input);
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float output;
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if (abs_sample < (1.0f / A_LAW_A)) {
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output = sign * (A_LAW_A * abs_sample) / (1.0f + std::log(A_LAW_A));
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} else {
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output =
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sign * (1.0f + std::log(A_LAW_A * abs_sample)) / (1.0f + std::log(A_LAW_A));
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}
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return output;
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}
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inline float alaw_decode(float input)
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{
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float sign = (input >= 0.0f) ? 1.0f : -1.0f;
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float abs_comp = std::fabs(input);
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float sample;
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if (abs_comp < (1.0f / (1.0f + std::log(A_LAW_A)))) {
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sample = sign * (abs_comp * (1.0f + std::log(A_LAW_A))) / A_LAW_A;
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} else {
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sample = sign * std::exp(abs_comp * (1.0f + std::log(A_LAW_A)) - 1.0f) / A_LAW_A;
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}
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return sample;
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}
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} // namespace trnr
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