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/*
* This file is part of AtracDEnc.
*
* AtracDEnc is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* AtracDEnc is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with AtracDEnc; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "qmf.h"
#include <lib/fft/kissfft_impl/tools/kiss_fftr.h>
#include <iostream>
static const float TapHalf[24] = {
-0.00001461907, -0.00009205479, -0.000056157569, 0.00030117269,
0.0002422519, -0.00085293897, -0.0005205574, 0.0020340169,
0.00078333891, -0.0042153862, -0.00075614988, 0.0078402944,
-0.000061169922, -0.01344162, 0.0024626821, 0.021736089,
-0.007801671, -0.034090221, 0.01880949, 0.054326009,
-0.043596379, -0.099384367, 0.13207909, 0.46424159
};
float TQmfCommon::QmfWindow[48];
TQmfCommon::TQmfCommon() noexcept
{
if (QmfWindow[0]) {
return;
}
const int sz = sizeof(QmfWindow)/sizeof(QmfWindow[0]);
for (size_t i = 0 ; i < sz/2; i++) {
QmfWindow[i] = QmfWindow[ sz - 1 - i] = TapHalf[i] * 2.0;
}
}
bool TQmfCommon::CalcFreqResp(size_t sz, float* buf) noexcept
{
size_t fftSz = sz * 2;
if (fftSz < 48) {
return false;
}
kiss_fftr_cfg fftCtx = kiss_fftr_alloc(fftSz, 0, NULL, NULL);
if (!fftCtx) {
return false;
}
kiss_fft_scalar* input = (kiss_fft_scalar*)KISS_FFT_MALLOC(sizeof(kiss_fft_scalar) * fftSz);
if (!input) {
kiss_fftr_free(fftCtx);
return false;
}
memset(input, 0, (sizeof(kiss_fft_scalar) * fftSz));
const size_t start = (sz - 48) / 2;
for (size_t i = start, j = 0; j < 48; i++, j++) {
input[i] = QmfWindow[j] / 2.0;
}
kiss_fft_cpx* res = (kiss_fft_cpx*)KISS_FFT_MALLOC(sizeof(kiss_fft_cpx) * (sz + 1));
if (!res) {
kiss_fftr_free(input);
kiss_fftr_free(fftCtx);
return false;
}
kiss_fftr(fftCtx, input, res);
for (size_t i = 0; i < sz; i++) {
buf[i] = res[i].r * res[i].r + res[i].i * res[i].i;
}
kiss_fftr_free(res);
kiss_fftr_free(input);
kiss_fftr_free(fftCtx);
return true;
}
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