55 lines
1.7 KiB
C
55 lines
1.7 KiB
C
/*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <math.h>
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#include <stdint.h>
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#include <stdio.h>
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#include "libavutil/libm.h"
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#include "libavcodec/iirfilter.h"
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#define FILT_ORDER 4
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#define SIZE 1024
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int main(void)
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{
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struct FFIIRFilterCoeffs *fcoeffs = NULL;
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struct FFIIRFilterState *fstate = NULL;
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float cutoff_coeff = 0.4;
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int16_t x[SIZE], y[SIZE];
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int i;
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fcoeffs = ff_iir_filter_init_coeffs(NULL, FF_FILTER_TYPE_BUTTERWORTH,
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FF_FILTER_MODE_LOWPASS, FILT_ORDER,
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cutoff_coeff, 0.0, 0.0);
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fstate = ff_iir_filter_init_state(FILT_ORDER);
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for (i = 0; i < SIZE; i++)
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x[i] = lrint(0.75 * INT16_MAX * sin(0.5 * M_PI * i * i / SIZE));
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ff_iir_filter(fcoeffs, fstate, SIZE, x, 1, y, 1);
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for (i = 0; i < SIZE; i++)
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printf("%6d %6d\n", x[i], y[i]);
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ff_iir_filter_free_coeffs(fcoeffs);
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ff_iir_filter_free_state(fstate);
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return 0;
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}
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