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src/processors/other/poly_octave/PolyOctaveFilterBandHelpers.h
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| #pragma once | ||
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| #include "PolyOctave.h" | ||
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| namespace FilterBankHelpers | ||
| { | ||
| // Reference for filter-bank design and octave shifting: | ||
| // https://aaltodoc.aalto.fi/server/api/core/bitstreams/ff9e52cf-fd79-45eb-b695-93038244ec0e/content | ||
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| using float_2 = PolyOctave::ComplexERBFilterBank::float_2; | ||
| static_assert (float_2::size == 2); | ||
| static_assert (xsimd::batch<double>::size == 2); | ||
| static constexpr auto vec_size = float_2::size; | ||
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| template <bool isImag = false> | ||
| inline float_2 processSample (const chowdsp::IIRFilter<4, float_2>& f, std::array<float_2, 5>& z, float_2 x) | ||
| { | ||
| auto y = z[1]; | ||
| if constexpr (! isImag) | ||
| y += x * f.b[0]; // for the imaginary filter, we know that b[0] == 0 | ||
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| z[1] = z[2] + x * f.b[1] - y * f.a[1]; | ||
| z[2] = z[3] + x * f.b[2] - y * f.a[2]; | ||
| z[3] = z[4] + x * f.b[3] - y * f.a[3]; | ||
| z[4] = x * f.b[4] - y * f.a[4]; | ||
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| return y; | ||
| } | ||
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| static constexpr auto q_c = 4.0; | ||
| static auto designERBFilter (size_t erb_index, | ||
| double gamma, | ||
| double erb_start, | ||
| double q_ERB, | ||
| double sample_rate, | ||
| double (&b_coeffs_cplx_real)[5], | ||
| double (&b_coeffs_cplx_imag)[5], | ||
| double (&a_coeffs_cplx)[5]) | ||
| { | ||
| const auto q_PS = gamma; | ||
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| const auto z = erb_start + static_cast<float> (erb_index) * (q_c / q_ERB); | ||
| const auto center_target_freq = 228.7 * (std::pow (10.0, z / 21.3) - 1.0); | ||
| const auto filter_q = (1.0 / (q_PS * q_ERB)) * (24.7 + 0.108 * center_target_freq); | ||
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| double b_coeffs_proto[3]; | ||
| double a_coeffs_proto[3]; | ||
| chowdsp::CoefficientCalculators::calcSecondOrderBPF (b_coeffs_proto, | ||
| a_coeffs_proto, | ||
| center_target_freq / gamma, | ||
| filter_q * 0.5, | ||
| sample_rate); | ||
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| auto pole = (std::sqrt (std::pow (std::complex { a_coeffs_proto[1] }, 2.0) - 4.0 * a_coeffs_proto[2]) - a_coeffs_proto[1]) / 2.0; | ||
| auto conj_pole = std::conj (pole); | ||
| if (std::imag (pole) < 0.0) | ||
| pole = conj_pole; | ||
| else if (std::imag (conj_pole) < 0.0) | ||
| conj_pole = pole; | ||
| auto at = -(pole + conj_pole); | ||
| auto att = pole * conj_pole; | ||
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| auto ar1 = std::real (at); | ||
| auto ai1 = std::imag (at); | ||
| auto ar2 = std::real (att); | ||
| auto ai2 = std::imag (att); | ||
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| // a[] = 1 + 2 ar1 z + (ai1^2 + ar1^2 + 2 ar2) z^2 + (2 ai1 ai2 + 2 ar1 ar2) z^3 + (ai2^2 + ar2^2) z^4 | ||
| a_coeffs_cplx[0] = 1.0; | ||
| a_coeffs_cplx[1] = 2.0 * ar1; | ||
| a_coeffs_cplx[2] = ai1 * ai1 + ar1 * ar1 + 2.0 * ar2; | ||
| a_coeffs_cplx[3] = 2.0 * ai1 * ai2 + 2.0 * ar1 * ar2; | ||
| a_coeffs_cplx[4] = ai2 * ai2 + ar2 * ar2; | ||
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| // b_real[] = b0 + (ar1 b0 + b1) z + (ar2 b0 + ar1 b1 + b2) z^2 + (ar2 b1 + ar1 b2) z^3 + ar2 b2 z^4 | ||
| b_coeffs_cplx_real[0] = b_coeffs_proto[0]; | ||
| b_coeffs_cplx_real[1] = ar1 * b_coeffs_proto[0] + b_coeffs_proto[1]; | ||
| b_coeffs_cplx_real[2] = ar2 * b_coeffs_proto[0] + ar1 * b_coeffs_proto[1] + b_coeffs_proto[2]; | ||
| b_coeffs_cplx_real[3] = ar2 * b_coeffs_proto[1] + ar1 * b_coeffs_proto[2]; | ||
| b_coeffs_cplx_real[4] = ar2 * b_coeffs_proto[2]; | ||
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| // b_imag[] = -ai1 b0 z - (ai2 b0 + ai1 b1) z^2 - (ai2 b1 + ai1 br) z^3 - ai2 br z^4 | ||
| b_coeffs_cplx_imag[0] = 0.0; | ||
| b_coeffs_cplx_imag[1] = -ai1 * b_coeffs_proto[0]; | ||
| b_coeffs_cplx_imag[2] = -ai2 * b_coeffs_proto[0] - ai1 * b_coeffs_proto[1]; | ||
| b_coeffs_cplx_imag[3] = -ai2 * b_coeffs_proto[1] - ai1 * b_coeffs_proto[2]; | ||
| b_coeffs_cplx_imag[4] = -ai2 * b_coeffs_proto[2]; | ||
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| return center_target_freq; | ||
| } | ||
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| static void designFilterBank (std::array<PolyOctave::ComplexERBFilterBank, 2>& filterBank, | ||
| double gamma, | ||
| double erb_start, | ||
| double q_ERB, | ||
| double sampleRate) | ||
| { | ||
| for (size_t kiter = 0; kiter < PolyOctave::ComplexERBFilterBank::numFilterBands; kiter += vec_size) | ||
| { | ||
| alignas (16) std::array<float_2::value_type, float_2::size> b_coeffs_cplx_real_simd[5]; | ||
| alignas (16) std::array<float_2::value_type, float_2::size> b_coeffs_cplx_imag_simd[5]; | ||
| alignas (16) std::array<float_2::value_type, float_2::size> a_coeffs_cplx_simd[5]; | ||
| alignas (16) std::array<float_2::value_type, float_2::size> center_freqs; | ||
| for (size_t i = 0; i < float_2::size; ++i) | ||
| { | ||
| const auto k = kiter + i; | ||
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| double b_coeffs_cplx_real[5]; | ||
| double b_coeffs_cplx_imag[5]; | ||
| double a_coeffs_cplx[5]; | ||
| center_freqs[i] = designERBFilter (k, | ||
| gamma, | ||
| erb_start, | ||
| q_ERB, | ||
| sampleRate, | ||
| b_coeffs_cplx_real, | ||
| b_coeffs_cplx_imag, | ||
| a_coeffs_cplx); | ||
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| for (size_t c = 0; c < 5; ++c) | ||
| { | ||
| b_coeffs_cplx_real_simd[c][i] = static_cast<float_2::value_type> (b_coeffs_cplx_real[c]); | ||
| b_coeffs_cplx_imag_simd[c][i] = static_cast<float_2::value_type> (b_coeffs_cplx_imag[c]); | ||
| a_coeffs_cplx_simd[c][i] = static_cast<float_2::value_type> (a_coeffs_cplx[c]); | ||
| } | ||
| } | ||
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| for (size_t ch = 0; ch < 2; ++ch) | ||
| { | ||
| filterBank[ch].erbFilterReal[kiter / vec_size].reset(); | ||
| filterBank[ch].erbFilterReal[kiter / vec_size].setCoefs ({ | ||
| xsimd::load_aligned (b_coeffs_cplx_real_simd[0].data()), | ||
| xsimd::load_aligned (b_coeffs_cplx_real_simd[1].data()), | ||
| xsimd::load_aligned (b_coeffs_cplx_real_simd[2].data()), | ||
| xsimd::load_aligned (b_coeffs_cplx_real_simd[3].data()), | ||
| xsimd::load_aligned (b_coeffs_cplx_real_simd[4].data()), | ||
| }, | ||
| { | ||
| xsimd::load_aligned (a_coeffs_cplx_simd[0].data()), | ||
| xsimd::load_aligned (a_coeffs_cplx_simd[1].data()), | ||
| xsimd::load_aligned (a_coeffs_cplx_simd[2].data()), | ||
| xsimd::load_aligned (a_coeffs_cplx_simd[3].data()), | ||
| xsimd::load_aligned (a_coeffs_cplx_simd[4].data()), | ||
| }); | ||
| filterBank[ch].erbFilterImag[kiter / vec_size].reset(); | ||
| filterBank[ch].erbFilterImag[kiter / vec_size].setCoefs ({ | ||
| xsimd::load_aligned (b_coeffs_cplx_imag_simd[0].data()), | ||
| xsimd::load_aligned (b_coeffs_cplx_imag_simd[1].data()), | ||
| xsimd::load_aligned (b_coeffs_cplx_imag_simd[2].data()), | ||
| xsimd::load_aligned (b_coeffs_cplx_imag_simd[3].data()), | ||
| xsimd::load_aligned (b_coeffs_cplx_imag_simd[4].data()), | ||
| }, | ||
| { | ||
| xsimd::load_aligned (a_coeffs_cplx_simd[0].data()), | ||
| xsimd::load_aligned (a_coeffs_cplx_simd[1].data()), | ||
| xsimd::load_aligned (a_coeffs_cplx_simd[2].data()), | ||
| xsimd::load_aligned (a_coeffs_cplx_simd[3].data()), | ||
| xsimd::load_aligned (a_coeffs_cplx_simd[4].data()), | ||
| }); | ||
| } | ||
| } | ||
| } | ||
| } // namespace FilterBankHelpers |