X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=libavcodec%2Fiirfilter.c;h=f9b9ff60d42ea751860ae2ce9bac8399c2986f0c;hb=eb239a577fcf1f19cdaa7aeb6e6586a172ee59c1;hp=62c2a61cd57c4ac4e5604e0c0df01f9a48059c72;hpb=bad5537e2c2caeb5deb1ff9d771ea01058b8010c;p=ffmpeg diff --git a/libavcodec/iirfilter.c b/libavcodec/iirfilter.c index 62c2a61cd57..f9b9ff60d42 100644 --- a/libavcodec/iirfilter.c +++ b/libavcodec/iirfilter.c @@ -2,31 +2,31 @@ * 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 */ /** - * @file libavcodec/iirfilter.c + * @file * different IIR filters implementation */ #include "iirfilter.h" -#include #include +#include "libavutil/common.h" /** * IIR filter global parameters @@ -48,25 +48,25 @@ typedef struct FFIIRFilterState{ /// maximum supported filter order #define MAXORDER 30 -struct FFIIRFilterCoeffs* ff_iir_filter_init_coeffs(enum IIRFilterType filt_type, - enum IIRFilterMode filt_mode, - int order, float cutoff_ratio, - float stopband, float ripple) +static int butterworth_init_coeffs(void *avc, struct FFIIRFilterCoeffs *c, + enum IIRFilterMode filt_mode, + int order, float cutoff_ratio, + float stopband) { - int i, j, size; - FFIIRFilterCoeffs *c; + int i, j; double wa; - complex p[MAXORDER + 1]; - - if(filt_type != FF_FILTER_TYPE_BUTTERWORTH || filt_mode != FF_FILTER_MODE_LOWPASS) - return NULL; - if(order <= 1 || (order & 1) || order > MAXORDER || cutoff_ratio >= 1.0) - return NULL; + double p[MAXORDER + 1][2]; - c = av_malloc(sizeof(FFIIRFilterCoeffs)); - c->cx = av_malloc(sizeof(c->cx[0]) * ((order >> 1) + 1)); - c->cy = av_malloc(sizeof(c->cy[0]) * order); - c->order = order; + if (filt_mode != FF_FILTER_MODE_LOWPASS) { + av_log(avc, AV_LOG_ERROR, "Butterworth filter currently only supports " + "low-pass filter mode\n"); + return -1; + } + if (order & 1) { + av_log(avc, AV_LOG_ERROR, "Butterworth filter currently only supports " + "even filter orders\n"); + return -1; + } wa = 2 * tan(M_PI * 0.5 * cutoff_ratio); @@ -74,86 +74,235 @@ struct FFIIRFilterCoeffs* ff_iir_filter_init_coeffs(enum IIRFilterType filt_type for(i = 1; i < (order >> 1) + 1; i++) c->cx[i] = c->cx[i - 1] * (order - i + 1LL) / i; - p[0] = 1.0; + p[0][0] = 1.0; + p[0][1] = 0.0; for(i = 1; i <= order; i++) - p[i] = 0.0; + p[i][0] = p[i][1] = 0.0; for(i = 0; i < order; i++){ - complex zp; + double zp[2]; double th = (i + (order >> 1) + 0.5) * M_PI / order; - zp = cexp(I*th) * wa; - zp = (zp + 2.0) / (zp - 2.0); + double a_re, a_im, c_re, c_im; + zp[0] = cos(th) * wa; + zp[1] = sin(th) * wa; + a_re = zp[0] + 2.0; + c_re = zp[0] - 2.0; + a_im = + c_im = zp[1]; + zp[0] = (a_re * c_re + a_im * c_im) / (c_re * c_re + c_im * c_im); + zp[1] = (a_im * c_re - a_re * c_im) / (c_re * c_re + c_im * c_im); for(j = order; j >= 1; j--) - p[j] = zp*p[j] + p[j - 1]; - p[0] *= zp; + { + a_re = p[j][0]; + a_im = p[j][1]; + p[j][0] = a_re*zp[0] - a_im*zp[1] + p[j-1][0]; + p[j][1] = a_re*zp[1] + a_im*zp[0] + p[j-1][1]; + } + a_re = p[0][0]*zp[0] - p[0][1]*zp[1]; + p[0][1] = p[0][0]*zp[1] + p[0][1]*zp[0]; + p[0][0] = a_re; } - c->gain = creal(p[order]); + c->gain = p[order][0]; for(i = 0; i < order; i++){ - c->gain += creal(p[i]); - c->cy[i] = creal(-p[i] / p[order]); + c->gain += p[i][0]; + c->cy[i] = (-p[i][0] * p[order][0] + -p[i][1] * p[order][1]) / + (p[order][0] * p[order][0] + p[order][1] * p[order][1]); } c->gain /= 1 << order; - return c; + return 0; +} + +static int biquad_init_coeffs(void *avc, struct FFIIRFilterCoeffs *c, + enum IIRFilterMode filt_mode, int order, + float cutoff_ratio, float stopband) +{ + double cos_w0, sin_w0; + double a0, x0, x1; + + if (filt_mode != FF_FILTER_MODE_HIGHPASS && + filt_mode != FF_FILTER_MODE_LOWPASS) { + av_log(avc, AV_LOG_ERROR, "Biquad filter currently only supports " + "high-pass and low-pass filter modes\n"); + return -1; + } + if (order != 2) { + av_log(avc, AV_LOG_ERROR, "Biquad filter must have order of 2\n"); + return -1; + } + + cos_w0 = cos(M_PI * cutoff_ratio); + sin_w0 = sin(M_PI * cutoff_ratio); + + a0 = 1.0 + (sin_w0 / 2.0); + + if (filt_mode == FF_FILTER_MODE_HIGHPASS) { + c->gain = ((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) / 2.0) / a0; + x1 = (1.0 - cos_w0) / 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); + + return 0; +} + +av_cold struct FFIIRFilterCoeffs* ff_iir_filter_init_coeffs(void *avc, + enum IIRFilterType filt_type, + enum IIRFilterMode filt_mode, + int order, float cutoff_ratio, + float stopband, float ripple) +{ + FFIIRFilterCoeffs *c; + int ret = 0; + + if (order <= 0 || order > MAXORDER || cutoff_ratio >= 1.0) + return NULL; + + FF_ALLOCZ_OR_GOTO(avc, c, sizeof(FFIIRFilterCoeffs), + init_fail); + FF_ALLOC_OR_GOTO (avc, c->cx, sizeof(c->cx[0]) * ((order >> 1) + 1), + init_fail); + FF_ALLOC_OR_GOTO (avc, c->cy, sizeof(c->cy[0]) * order, + init_fail); + c->order = order; + + switch (filt_type) { + case FF_FILTER_TYPE_BUTTERWORTH: + ret = butterworth_init_coeffs(avc, c, filt_mode, order, cutoff_ratio, + stopband); + break; + case FF_FILTER_TYPE_BIQUAD: + ret = biquad_init_coeffs(avc, c, filt_mode, order, cutoff_ratio, + stopband); + break; + default: + av_log(avc, AV_LOG_ERROR, "filter type is not currently implemented\n"); + goto init_fail; + } + + if (!ret) + return c; + +init_fail: + ff_iir_filter_free_coeffs(c); + return NULL; } -struct FFIIRFilterState* ff_iir_filter_init_state(int order) +av_cold struct FFIIRFilterState* ff_iir_filter_init_state(int order) { FFIIRFilterState* s = av_mallocz(sizeof(FFIIRFilterState) + sizeof(s->x[0]) * (order - 1)); return s; } -#define FILTER(i0, i1, i2, i3) \ - in = *src * c->gain \ - + c->cy[0]*s->x[i0] + c->cy[1]*s->x[i1] \ - + c->cy[2]*s->x[i2] + c->cy[3]*s->x[i3]; \ - res = (s->x[i0] + in )*1 \ - + (s->x[i1] + s->x[i3])*4 \ - + s->x[i2] *6; \ - *dst = av_clip_int16(lrintf(res)); \ - s->x[i0] = in; \ - src += sstep; \ - dst += 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) -{ - int i; +#define CONV_S16(dest, source) dest = av_clip_int16(lrintf(source)); - if(c->order == 4){ - for(i = 0; i < size; i += 4){ - float in, res; +#define CONV_FLT(dest, source) dest = source; - FILTER(0, 1, 2, 3); - FILTER(1, 2, 3, 0); - FILTER(2, 3, 0, 1); - FILTER(3, 0, 1, 2); - } - }else{ - for(i = 0; i < size; i++){ - int j; - float in, res; - in = *src * c->gain; - for(j = 0; j < c->order; j++) - in += c->cy[j] * s->x[j]; - res = s->x[0] + in + s->x[c->order >> 1] * c->cx[c->order >> 1]; - for(j = 1; j < c->order >> 1; j++) - res += (s->x[j] + s->x[c->order - j]) * c->cx[j]; - for(j = 0; j < c->order - 1; j++) - s->x[j] = s->x[j + 1]; - *dst = av_clip_int16(lrintf(res)); - s->x[c->order - 1] = in; - src += sstep; - dst += sstep; - } +#define FILTER_BW_O4_1(i0, i1, i2, i3, fmt) \ + in = *src0 * c->gain \ + + c->cy[0]*s->x[i0] + c->cy[1]*s->x[i1] \ + + c->cy[2]*s->x[i2] + c->cy[3]*s->x[i3]; \ + res = (s->x[i0] + in )*1 \ + + (s->x[i1] + s->x[i3])*4 \ + + s->x[i2] *6; \ + CONV_##fmt(*dst0, res) \ + s->x[i0] = in; \ + src0 += sstep; \ + dst0 += dstep; + +#define FILTER_BW_O4(type, fmt) { \ + int i; \ + const type *src0 = src; \ + type *dst0 = dst; \ + for (i = 0; i < size; i += 4) { \ + float in, res; \ + FILTER_BW_O4_1(0, 1, 2, 3, fmt); \ + FILTER_BW_O4_1(1, 2, 3, 0, fmt); \ + FILTER_BW_O4_1(2, 3, 0, 1, fmt); \ + FILTER_BW_O4_1(3, 0, 1, 2, fmt); \ + } \ +} + +#define FILTER_DIRECT_FORM_II(type, fmt) { \ + int i; \ + const type *src0 = src; \ + type *dst0 = dst; \ + for (i = 0; i < size; i++) { \ + int j; \ + float in, res; \ + in = *src0 * c->gain; \ + for(j = 0; j < c->order; j++) \ + in += c->cy[j] * s->x[j]; \ + res = s->x[0] + in + s->x[c->order >> 1] * c->cx[c->order >> 1]; \ + for(j = 1; j < c->order >> 1; j++) \ + res += (s->x[j] + s->x[c->order - j]) * c->cx[j]; \ + for(j = 0; j < c->order - 1; j++) \ + s->x[j] = s->x[j + 1]; \ + CONV_##fmt(*dst0, res) \ + s->x[c->order - 1] = in; \ + src0 += sstep; \ + dst0 += dstep; \ + } \ +} + +#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 == 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) } } -void ff_iir_filter_free_state(struct FFIIRFilterState *state) +void ff_iir_filter_flt(const struct FFIIRFilterCoeffs *c, + struct FFIIRFilterState *s, int size, + const float *src, int sstep, float *dst, int dstep) +{ + 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) + } +} + +av_cold void ff_iir_filter_free_state(struct FFIIRFilterState *state) { av_free(state); } -void ff_iir_filter_free_coeffs(struct FFIIRFilterCoeffs *coeffs) +av_cold void ff_iir_filter_free_coeffs(struct FFIIRFilterCoeffs *coeffs) { if(coeffs){ av_free(coeffs->cx); @@ -162,3 +311,36 @@ void ff_iir_filter_free_coeffs(struct FFIIRFilterCoeffs *coeffs) av_free(coeffs); } +#ifdef TEST +#undef printf +#include + +#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_coeffs(fcoeffs); + ff_iir_filter_free_state(fstate); + return 0; +} +#endif /* TEST */