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];
108 c->gain = p[order][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]);
114 c->gain /= 1 << order;
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)
207 #define CONV_S16(dest, source) dest = av_clip_int16(lrintf(source));
209 #define CONV_FLT(dest, source) dest = source;
211 #define FILTER_BW_O4_1(i0, i1, i2, i3, fmt) \
212 in = *src0 * c->gain + \
213 c->cy[0] * s->x[i0] + \
214 c->cy[1] * s->x[i1] + \
215 c->cy[2] * s->x[i2] + \
216 c->cy[3] * s->x[i3]; \
217 res = (s->x[i0] + in) * 1 + \
218 (s->x[i1] + s->x[i3]) * 4 + \
220 CONV_ ## fmt(*dst0, res) \
225 #define FILTER_BW_O4(type, fmt) { \
227 const type *src0 = src; \
229 for (i = 0; i < size; i += 4) { \
231 FILTER_BW_O4_1(0, 1, 2, 3, fmt); \
232 FILTER_BW_O4_1(1, 2, 3, 0, fmt); \
233 FILTER_BW_O4_1(2, 3, 0, 1, fmt); \
234 FILTER_BW_O4_1(3, 0, 1, 2, fmt); \
238 #define FILTER_DIRECT_FORM_II(type, fmt) { \
240 const type *src0 = src; \
242 for (i = 0; i < size; i++) { \
245 in = *src0 * c->gain; \
246 for (j = 0; j < c->order; j++) \
247 in += c->cy[j] * s->x[j]; \
248 res = s->x[0] + in + s->x[c->order >> 1] * c->cx[c->order >> 1]; \
249 for (j = 1; j < c->order >> 1; j++) \
250 res += (s->x[j] + s->x[c->order - j]) * c->cx[j]; \
251 for (j = 0; j < c->order - 1; j++) \
252 s->x[j] = s->x[j + 1]; \
253 CONV_ ## fmt(*dst0, res) \
254 s->x[c->order - 1] = in; \
260 #define FILTER_O2(type, fmt) { \
262 const type *src0 = src; \
264 for (i = 0; i < size; i++) { \
265 float in = *src0 * c->gain + \
266 s->x[0] * c->cy[0] + \
267 s->x[1] * c->cy[1]; \
268 CONV_ ## fmt(*dst0, s->x[0] + in + s->x[1] * c->cx[1]) \
278 const int16_t *
src, ptrdiff_t sstep,
279 int16_t *dst, ptrdiff_t dstep)
283 }
else if (
c->order == 4) {
292 const float *
src, ptrdiff_t sstep,
293 float *dst, ptrdiff_t dstep)
297 }
else if (
c->order == 4) {
Macro definitions for various function/variable attributes.
common internal and external API header
#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...
#define FILTER_O2(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.
#define FILTER_DIRECT_FORM_II(type, fmt)
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.
#define MAXORDER
maximum supported filter order
av_cold void ff_iir_filter_free_coeffsp(struct FFIIRFilterCoeffs **coeffsp)
Free filter coefficients.
void ff_iir_filter_init(FFIIRFilterContext *f)
Initialize FFIIRFilterContext.
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.
static av_cold int butterworth_init_coeffs(void *avc, struct FFIIRFilterCoeffs *c, enum IIRFilterMode filt_mode, int order, float cutoff_ratio, float stopband)
#define FILTER_BW_O4(type, fmt)
av_cold void ff_iir_filter_free_statep(struct FFIIRFilterState **state)
Free and zero filter state.
av_cold struct FFIIRFilterState * ff_iir_filter_init_state(int order)
Create new filter state.
static av_cold int biquad_init_coeffs(void *avc, struct FFIIRFilterCoeffs *c, enum IIRFilterMode filt_mode, int order, float cutoff_ratio, float stopband)
@ FF_FILTER_MODE_HIGHPASS
void ff_iir_filter_init_mips(FFIIRFilterContext *f)
@ FF_FILTER_TYPE_BUTTERWORTH
IIR filter global parameters.