| /* |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg 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. |
| * |
| * FFmpeg 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 FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| #include <math.h> |
| #include <stdint.h> |
| #include <stdio.h> |
| |
| #include "libavutil/libm.h" |
| |
| #include "libavcodec/iirfilter.h" |
| |
| #define FILT_ORDER 4 |
| #define SIZE 1024 |
| |
| int main(void) |
| { |
| struct FFIIRFilterCoeffs *fcoeffs = NULL; |
| struct FFIIRFilterState *fstate = NULL; |
| float cutoff_coeff = 0.4; |
| int16_t x[SIZE], y[SIZE]; |
| int i; |
| |
| fcoeffs = ff_iir_filter_init_coeffs(NULL, FF_FILTER_TYPE_BUTTERWORTH, |
| FF_FILTER_MODE_LOWPASS, FILT_ORDER, |
| cutoff_coeff, 0.0, 0.0); |
| fstate = ff_iir_filter_init_state(FILT_ORDER); |
| |
| for (i = 0; i < SIZE; i++) |
| x[i] = lrint(0.75 * INT16_MAX * sin(0.5 * M_PI * i * i / SIZE)); |
| |
| ff_iir_filter(fcoeffs, fstate, SIZE, x, 1, y, 1); |
| |
| for (i = 0; i < SIZE; i++) |
| printf("%6d %6d\n", x[i], y[i]); |
| |
| ff_iir_filter_free_coeffsp(&fcoeffs); |
| ff_iir_filter_free_statep(&fstate); |
| return 0; |
| } |