67 lines
2.1 KiB
C++
67 lines
2.1 KiB
C++
#include "loudness.h"
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#include "filter.h"
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#include "common.h"
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#include "mengumath.h"
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#include <complex>
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#include <cstdint>
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// Coefficients for LUFS_freq filteters
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// High shelf filter stage
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#define S1_A1 -1.69065929318241
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#define S1_A2 0.73248077421585
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#define S1_B0 1.53512485958697
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#define S1_B1 -2.69169618940638
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#define S1_B2 1.19839281085285
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// High pass Filter stage
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#define S2_A1 -1.99004745483398
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#define S2_A2 0.99007225036621
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#define S2_B0 1.0
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#define S2_B1 -2.0
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#define S2_B2 1.0
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#define LUFS_DEFAULT_SAMPLE_RATE 48000
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using namespace Mengu;
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using namespace dsp;
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float Mengu::dsp::LUFS_freq(Complex *freqs, uint32_t size, uint32_t sample_rate) {
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// Adjust to the custum sample rate
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float sample_rate_correction = (float) sample_rate / LUFS_DEFAULT_SAMPLE_RATE * 2;
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float total_amp2 = 0.0f; // total squared amplitude of each freq bin
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for (uint32_t i = 0; i < size; i++) {
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// argument for the transfer functions
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float omega = (float) MATH_PI * i / size * sample_rate_correction;
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Complex z = std::polar(1.0f, omega);
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// filtered frequency
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Complex y = freqs[i] * quad_filter_trans(z, S1_A1, S1_A2, S1_B0, S1_B1, S1_B2);
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y = y * quad_filter_trans(z, S2_A1, S2_A2, S2_B0, S2_B1, S2_B2);
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total_amp2 += std::norm(y);
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}
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return -0.691 + 10 * Mengu::log10(total_amp2 / size);
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}
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Complex Mengu::dsp::LUFS_filter_transfer(float freq) {
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float omega = (float) MATH_PI * freq / LUFS_DEFAULT_SAMPLE_RATE * 2;
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Complex z = std::polar(1.0f, omega);
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Complex y = quad_filter_trans(z, S1_A1, S1_A2, S1_B0, S1_B1, S1_B2);
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return y * quad_filter_trans(z, S2_A1, S2_A2, S2_B0, S2_B1, S2_B2);
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}
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LUFSFilter::LUFSFilter():
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_high_shelf_filter(S1_A1, S1_A2, S1_B0, S1_B1, S1_B2),
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_high_pass_filter(S2_A1, S2_A2, S2_B0, S2_B1, S2_B2) {}
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void LUFSFilter::transform(const float *input, float *output, uint32_t size) {
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_high_shelf_filter.transform(input, output, size);
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_high_pass_filter.transform(output, output, size);
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}
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void LUFSFilter::reset() {
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_high_shelf_filter.reset();
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_high_pass_filter.reset();
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} |