57 int order,
float cutoff_ratio,
66 "low-pass filter mode\n");
71 "even filter orders\n");
75 wa = 2 * tan(
M_PI * 0.5 * cutoff_ratio);
78 for (i = 1; i < (order >> 1) + 1; i++)
79 c->
cx[i] = c->
cx[i - 1] * (order - i + 1LL) / i;
83 for (i = 1; i <=
order; i++)
84 p[i][0] = p[i][1] = 0.0;
85 for (i = 0; i <
order; i++) {
87 double th = (i + (order >> 1) + 0.5) *
M_PI /
order;
88 double a_re, a_im, c_re, c_im;
95 zp[0] = (a_re * c_re + a_im * c_im) / (c_re * c_re + c_im * c_im);
96 zp[1] = (a_im * c_re - a_re * c_im) / (c_re * c_re + c_im * c_im);
98 for (j = order; j >= 1; j--) {
101 p[j][0] = a_re * zp[0] - a_im * zp[1] + p[j - 1][0];
102 p[j][1] = a_re * zp[1] + a_im * zp[0] + p[j - 1][1];
104 a_re = p[0][0] * zp[0] - p[0][1] * zp[1];
105 p[0][1] = p[0][0] * zp[1] + p[0][1] * zp[0];
109 for (i = 0; i <
order; i++) {
111 c->
cy[i] = (-p[i][0] * p[
order][0] + -p[i][1] * p[
order][1]) /
112 (p[order][0] * p[order][0] + p[order][1] * p[order][1]);
121 float cutoff_ratio,
float stopband)
123 double cos_w0, sin_w0;
129 "high-pass and low-pass filter modes\n");
137 cos_w0 = cos(
M_PI * cutoff_ratio);
138 sin_w0 = sin(
M_PI * cutoff_ratio);
140 a0 = 1.0 + (sin_w0 / 2.0);
143 c->
gain = ((1.0 + cos_w0) / 2.0) /
a0;
144 x0 = ((1.0 + cos_w0) / 2.0) /
a0;
145 x1 = (-(1.0 + cos_w0)) /
a0;
147 c->
gain = ((1.0 - cos_w0) / 2.0) /
a0;
148 x0 = ((1.0 - cos_w0) / 2.0) /
a0;
149 x1 = (1.0 - cos_w0) / a0;
151 c->
cy[0] = (-1.0 + (sin_w0 / 2.0)) / a0;
152 c->
cy[1] = (2.0 * cos_w0) / a0;
165 int order,
float cutoff_ratio,
166 float stopband,
float ripple)
171 if (order <= 0 || order >
MAXORDER || cutoff_ratio >= 1.0)
210 #define CONV_S16(dest, source) dest = av_clip_int16(lrintf(source)); 212 #define CONV_FLT(dest, source) dest = source; 214 #define FILTER_BW_O4_1(i0, i1, i2, i3, fmt) \ 215 in = *src0 * c->gain + \ 216 c->cy[0] * s->x[i0] + \ 217 c->cy[1] * s->x[i1] + \ 218 c->cy[2] * s->x[i2] + \ 219 c->cy[3] * s->x[i3]; \ 220 res = (s->x[i0] + in) * 1 + \ 221 (s->x[i1] + s->x[i3]) * 4 + \ 223 CONV_ ## fmt(*dst0, res) \ 228 #define FILTER_BW_O4(type, fmt) { \ 230 const type *src0 = src; \ 232 for (i = 0; i < size; i += 4) { \ 234 FILTER_BW_O4_1(0, 1, 2, 3, fmt); \ 235 FILTER_BW_O4_1(1, 2, 3, 0, fmt); \ 236 FILTER_BW_O4_1(2, 3, 0, 1, fmt); \ 237 FILTER_BW_O4_1(3, 0, 1, 2, fmt); \ 241 #define FILTER_DIRECT_FORM_II(type, fmt) { \ 243 const type *src0 = src; \ 245 for (i = 0; i < size; i++) { \ 248 in = *src0 * c->gain; \ 249 for (j = 0; j < c->order; j++) \ 250 in += c->cy[j] * s->x[j]; \ 251 res = s->x[0] + in + s->x[c->order >> 1] * c->cx[c->order >> 1]; \ 252 for (j = 1; j < c->order >> 1; j++) \ 253 res += (s->x[j] + s->x[c->order - j]) * c->cx[j]; \ 254 for (j = 0; j < c->order - 1; j++) \ 255 s->x[j] = s->x[j + 1]; \ 256 CONV_ ## fmt(*dst0, res) \ 257 s->x[c->order - 1] = in; \ 263 #define FILTER_O2(type, fmt) { \ 265 const type *src0 = src; \ 267 for (i = 0; i < size; i++) { \ 268 float in = *src0 * c->gain + \ 269 s->x[0] * c->cy[0] + \ 270 s->x[1] * c->cy[1]; \ 271 CONV_ ## fmt(*dst0, s->x[0] + in + s->x[1] * c->cx[1]) \ 281 const int16_t *
src, ptrdiff_t sstep,
282 int16_t *dst, ptrdiff_t dstep)
286 }
else if (c->
order == 4) {
295 const float *
src, ptrdiff_t sstep,
296 float *dst, ptrdiff_t dstep)
300 }
else if (c->
order == 4) {
static av_cold int biquad_init_coeffs(void *avc, struct FFIIRFilterCoeffs *c, enum IIRFilterMode filt_mode, int order, float cutoff_ratio, float stopband)
av_cold struct FFIIRFilterState * ff_iir_filter_init_state(int order)
Create new filter state.
Macro definitions for various function/variable attributes.
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)
Initialize filter coefficients.
void(* filter_flt)(const struct FFIIRFilterCoeffs *coeffs, struct FFIIRFilterState *state, int size, const float *src, ptrdiff_t sstep, float *dst, ptrdiff_t dstep)
Perform IIR filtering on floating-point input samples.
#define FILTER_DIRECT_FORM_II(type, fmt)
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
void * av_mallocz(size_t size)
Allocate a memory block with alignment suitable for all memory accesses (including vectors if availab...
av_cold void ff_iir_filter_free_statep(struct FFIIRFilterState **state)
Free and zero filter state.
#define FILTER_O2(type, fmt)
#define MAXORDER
maximum supported filter order
#define FILTER_BW_O4(type, fmt)
void ff_iir_filter(const struct FFIIRFilterCoeffs *c, struct FFIIRFilterState *s, int size, const int16_t *src, ptrdiff_t sstep, int16_t *dst, ptrdiff_t dstep)
Perform IIR filtering on signed 16-bit input samples.
static av_cold int butterworth_init_coeffs(void *avc, struct FFIIRFilterCoeffs *c, enum IIRFilterMode filt_mode, int order, float cutoff_ratio, float stopband)
void ff_iir_filter_flt(const struct FFIIRFilterCoeffs *c, struct FFIIRFilterState *s, int size, const float *src, ptrdiff_t sstep, float *dst, ptrdiff_t dstep)
Perform IIR filtering on floating-point input samples.
IIR filter global parameters.
void ff_iir_filter_init_mips(FFIIRFilterContext *f)
void ff_iir_filter_init(FFIIRFilterContext *f)
Initialize FFIIRFilterContext.
common internal and external API header
#define FF_ALLOC_OR_GOTO(ctx, p, size, label)
static const int16_t coeffs[]
av_cold void ff_iir_filter_free_coeffsp(struct FFIIRFilterCoeffs **coeffsp)
Free filter coefficients.
#define FF_ALLOCZ_OR_GOTO(ctx, p, size, label)