micheleandCursor
ab3651e678
Safeload mixer/EQ/master on the ADAU1701, persist AudioProfile in NVS, expose /api/audio routes and web UI controls, with host tests and manual sync. Co-authored-by: Cursor <cursoragent@cursor.com>
95 lines
2.2 KiB
C++
95 lines
2.2 KiB
C++
/**
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* @file BiquadDesign.cpp
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* @brief Biquad coefficient design and ADAU fixpoint helpers.
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*
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* DigiRadio firmware — https://github.com/manvalan/DigiRadio
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*
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* Copyright 2026 Michele Bigi
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* SPDX-License-Identifier: Apache-2.0
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*
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* @author Michele Bigi
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* @date 2026-07-06
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*/
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#include "core/BiquadDesign.hpp"
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#include <cmath>
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#include <numbers>
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namespace core {
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namespace {
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constexpr float kPi = std::numbers::pi_v<float>;
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[[nodiscard]] float clampQ(float q) noexcept
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{
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if (q < 0.2F) {
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return 0.2F;
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}
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if (q > 10.0F) {
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return 10.0F;
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}
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return q;
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}
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} // namespace
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std::int32_t floatToFixpoint823(float value) noexcept
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{
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const double scaled =
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static_cast<double>(value) * static_cast<double>(1U << 23);
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const auto rounded = static_cast<std::int64_t>(std::llround(scaled));
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return static_cast<std::int32_t>(rounded);
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}
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std::int32_t gainDbToLinearFixpoint(GainDb gain) noexcept
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{
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return floatToFixpoint823(gain.linear());
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}
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BiquadCoefficients designFlatEq() noexcept
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{
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return BiquadCoefficients{
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.b0 = 1.0F,
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.b1 = 0.0F,
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.b2 = 0.0F,
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.a0 = 0.0F,
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.a1 = 0.0F,
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};
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}
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BiquadCoefficients designPeakingEq(FrequencyHz center, GainDb gain,
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float q) noexcept
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{
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if (std::fabs(gain.value()) < 0.001F) {
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return designFlatEq();
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}
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const float qClamped = clampQ(q);
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const float fs = static_cast<float>(kAdauSampleRateHz);
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const float f0 = static_cast<float>(center.value());
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const float a = std::pow(10.0F, gain.value() / 40.0F);
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const float omega = 2.0F * kPi * f0 / fs;
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const float sinOmega = std::sin(omega);
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const float cosOmega = std::cos(omega);
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const float alpha = sinOmega / (2.0F * qClamped);
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const float b0 = 1.0F + alpha * a;
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const float b1 = -2.0F * cosOmega;
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const float b2 = 1.0F - alpha * a;
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const float a0 = 1.0F + alpha / a;
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const float a1 = -2.0F * cosOmega;
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const float a2 = 1.0F - alpha / a;
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return BiquadCoefficients{
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.b0 = b0 / a0,
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.b1 = b1 / a0,
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.b2 = b2 / a0,
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.a0 = a1 / a0,
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.a1 = a2 / a0,
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};
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}
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} // namespace core
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