* IIR filter
* Copyright (c) 2008 Konstantin Shishkov
*
- * This file is part of FFmpeg.
+ * This file is part of Libav.
*
- * FFmpeg is free software; you can redistribute it and/or
+ * Libav 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,
+ * Libav 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
+ * License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
if (filt_mode == FF_FILTER_MODE_HIGHPASS) {
c->gain = ((1.0 + cos_w0) / 2.0) / a0;
- x0 = (-(1.0 + cos_w0)) / a0;
- x1 = ((1.0 + cos_w0) / 2.0) / a0;
+ x0 = ((1.0 + cos_w0) / 2.0) / a0;
+ x1 = (-(1.0 + cos_w0)) / a0;
} else { // FF_FILTER_MODE_LOWPASS
c->gain = ((1.0 - cos_w0) / 2.0) / a0;
- x0 = (1.0 - cos_w0) / a0;
- x1 = ((1.0 - cos_w0) / 2.0) / a0;
+ x0 = ((1.0 - cos_w0) / 2.0) / a0;
+ x1 = (1.0 - cos_w0) / a0;
}
- c->cy[0] = (2.0 * cos_w0) / a0;
- c->cy[1] = (-1.0 + (sin_w0 / 2.0)) / a0;
+ c->cy[0] = (-1.0 + (sin_w0 / 2.0)) / a0;
+ c->cy[1] = (2.0 * cos_w0) / a0;
// divide by gain to make the x coeffs integers.
// during filtering, the delay state will include the gain multiplication
c->cx[0] = lrintf(x0 / c->gain);
c->cx[1] = lrintf(x1 / c->gain);
- c->cy[0] /= c->gain;
- c->cy[1] /= c->gain;
return 0;
}
} \
}
+#define FILTER_O2(type, fmt) { \
+ int i; \
+ const type *src0 = src; \
+ type *dst0 = dst; \
+ for (i = 0; i < size; i++) { \
+ float in = *src0 * c->gain + \
+ s->x[0] * c->cy[0] + \
+ s->x[1] * c->cy[1]; \
+ CONV_##fmt(*dst0, s->x[0] + in + s->x[1] * c->cx[1]) \
+ s->x[0] = s->x[1]; \
+ s->x[1] = in; \
+ src0 += sstep; \
+ dst0 += dstep; \
+ } \
+}
+
void ff_iir_filter(const struct FFIIRFilterCoeffs *c,
struct FFIIRFilterState *s, int size,
const int16_t *src, int sstep, int16_t *dst, int dstep)
{
- if (c->order == 4) {
+ if (c->order == 2) {
+ FILTER_O2(int16_t, S16)
+ } else if (c->order == 4) {
FILTER_BW_O4(int16_t, S16)
} else {
FILTER_DIRECT_FORM_II(int16_t, S16)
struct FFIIRFilterState *s, int size,
const float *src, int sstep, float *dst, int dstep)
{
- if (c->order == 4) {
+ if (c->order == 2) {
+ FILTER_O2(float, FLT)
+ } else if (c->order == 4) {
FILTER_BW_O4(float, FLT)
} else {
FILTER_DIRECT_FORM_II(float, FLT)
}
#ifdef TEST
+#undef printf
+#include <stdio.h>
+
#define FILT_ORDER 4
#define SIZE 1024
int main(void)
float cutoff_coeff = 0.4;
int16_t x[SIZE], y[SIZE];
int i;
- FILE* fd;
- fcoeffs = ff_iir_filter_init_coeffs(FF_FILTER_TYPE_BUTTERWORTH,
+ 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);
ff_iir_filter(fcoeffs, fstate, SIZE, x, 1, y, 1);
- fd = fopen("in.bin", "w");
- fwrite(x, sizeof(x[0]), SIZE, fd);
- fclose(fd);
-
- fd = fopen("out.bin", "w");
- fwrite(y, sizeof(y[0]), SIZE, fd);
- fclose(fd);
+ for (i = 0; i < SIZE; i++)
+ printf("%6d %6d\n", x[i], y[i]);
ff_iir_filter_free_coeffs(fcoeffs);
ff_iir_filter_free_state(fstate);