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avfilter/af_aiir: factor out response calculation

This commit is contained in:
Paul B Mahol 2019-11-22 16:04:13 +01:00
parent c36e72ed27
commit e169d3756e
1 changed files with 65 additions and 50 deletions
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115
libavfilter/af_aiir.c
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@ -737,6 +737,66 @@ static void draw_line(AVFrame *out, int x0, int y0, int x1, int y1, uint32_t col
}
}
static void get_response(int channel, int format, double w,
const double *b, const double *a,
int nb_b, int nb_a, double *r, double *i)
{
double realz, realp;
double imagz, imagp;
double real, imag;
double div;
if (format == 0) {
realz = 0., realp = 0.;
imagz = 0., imagp = 0.;
for (int x = 0; x < nb_a; x++) {
realz += cos(-x * w) * a[x];
imagz += sin(-x * w) * a[x];
}
for (int x = 0; x < nb_b; x++) {
realp += cos(-x * w) * b[x];
imagp += sin(-x * w) * b[x];
}
div = realp * realp + imagp * imagp;
real = (realz * realp + imagz * imagp) / div;
imag = (imagz * realp - imagp * realz) / div;
} else {
real = 1;
imag = 0;
for (int x = 0; x < nb_a; x++) {
double ore, oim, re, im;
re = cos(w) - a[2 * x];
im = sin(w) - a[2 * x + 1];
ore = real;
oim = imag;
real = ore * re - oim * im;
imag = ore * im + oim * re;
}
for (int x = 0; x < nb_b; x++) {
double ore, oim, re, im;
re = cos(w) - b[2 * x];
im = sin(w) - b[2 * x + 1];
ore = real;
oim = imag;
div = re * re + im * im;
real = (ore * re + oim * im) / div;
imag = (oim * re - ore * im) / div;
}
}
*r = real;
*i = imag;
}
static void draw_response(AVFilterContext *ctx, AVFrame *out)
{
AudioIIRContext *s = ctx->priv;
@ -744,7 +804,7 @@ static void draw_response(AVFilterContext *ctx, AVFrame *out)
float min_delay = FLT_MAX, max_delay = FLT_MIN;
int prev_ymag = -1, prev_yphase = -1, prev_ydelay = -1;
char text[32];
int ch, i, x;
int ch, i;
memset(out->data[0], 0, s->h * out->linesize[0]);
@ -758,57 +818,12 @@ static void draw_response(AVFilterContext *ctx, AVFrame *out)
for (i = 0; i < s->w; i++) {
const double *b = s->iir[ch].ab[0];
const double *a = s->iir[ch].ab[1];
const int nb_b = s->iir[ch].nb_ab[0];
const int nb_a = s->iir[ch].nb_ab[1];
double w = i * M_PI / (s->w - 1);
double realz, realp;
double imagz, imagp;
double real, imag, div;
double real, imag;
if (s->format == 0) {
realz = 0., realp = 0.;
imagz = 0., imagp = 0.;
for (x = 0; x < s->iir[ch].nb_ab[1]; x++) {
realz += cos(-x * w) * a[x];
imagz += sin(-x * w) * a[x];
}
for (x = 0; x < s->iir[ch].nb_ab[0]; x++) {
realp += cos(-x * w) * b[x];
imagp += sin(-x * w) * b[x];
}
div = realp * realp + imagp * imagp;
real = (realz * realp + imagz * imagp) / div;
imag = (imagz * realp - imagp * realz) / div;
} else {
real = 1;
imag = 0;
for (x = 0; x < s->iir[ch].nb_ab[1]; x++) {
double ore, oim, re, im;
re = cos(w) - a[2 * x];
im = sin(w) - a[2 * x + 1];
ore = real;
oim = imag;
real = ore * re - oim * im;
imag = ore * im + oim * re;
}
for (x = 0; x < s->iir[ch].nb_ab[0]; x++) {
double ore, oim, re, im;
re = cos(w) - b[2 * x];
im = sin(w) - b[2 * x + 1];
ore = real;
oim = imag;
div = re * re + im * im;
real = (ore * re + oim * im) / div;
imag = (oim * re - ore * im) / div;
}
}
get_response(ch, s->format, w, b, a, nb_b, nb_a, &real, &imag);
mag[i] = s->iir[ch].g * hypot(real, imag);
phase[i] = atan2(imag, real);