avfilter/af_acrossover: use transposed direct II form

This commit is contained in:
Paul B Mahol 2020-11-25 22:23:50 +01:00
parent 810e213fab
commit bc529ea9bc

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@ -41,8 +41,7 @@
typedef struct BiquadContext { typedef struct BiquadContext {
double a0, a1, a2; double a0, a1, a2;
double b1, b2; double b1, b2;
double i1, i2; double z1, z2;
double o1, o2;
} BiquadContext; } BiquadContext;
typedef struct CrossoverChannel { typedef struct CrossoverChannel {
@ -150,8 +149,8 @@ static void set_lp(BiquadContext *b, double fc, double q, double sr)
b->a0 = (0.5 + beta - gamma) / 2.0; b->a0 = (0.5 + beta - gamma) / 2.0;
b->a1 = 0.5 + beta - gamma; b->a1 = 0.5 + beta - gamma;
b->a2 = b->a1 / 2.0; b->a2 = b->a1 / 2.0;
b->b1 = -2.0 * gamma; b->b1 = 2.0 * gamma;
b->b2 = 2.0 * beta; b->b2 = -2.0 * beta;
} }
static void set_hp(BiquadContext *b, double fc, double q, double sr) static void set_hp(BiquadContext *b, double fc, double q, double sr)
@ -164,8 +163,8 @@ static void set_hp(BiquadContext *b, double fc, double q, double sr)
b->a0 = (0.5 + beta + gamma) / 2.0; b->a0 = (0.5 + beta + gamma) / 2.0;
b->a1 = -(0.5 + beta + gamma); b->a1 = -(0.5 + beta + gamma);
b->a2 = b->a0; b->a2 = b->a0;
b->b1 = -2.0 * gamma; b->b1 = 2.0 * gamma;
b->b2 = 2.0 * beta; b->b2 = -2.0 * beta;
} }
static void calc_q_factors(int order, double *q) static void calc_q_factors(int order, double *q)
@ -246,26 +245,21 @@ static void biquad_process(BiquadContext *b,
const double a2 = b->a2; const double a2 = b->a2;
const double b1 = b->b1; const double b1 = b->b1;
const double b2 = b->b2; const double b2 = b->b2;
double i1 = b->i1; double z1 = b->z1;
double i2 = b->i2; double z2 = b->z2;
double o1 = b->o1;
double o2 = b->o2;
for (int n = 0; n < nb_samples; n++) { for (int n = 0; n < nb_samples; n++) {
const double in = src[n]; const double in = src[n];
double out; double out;
out = in * a0 + i1 * a1 + i2 * a2 - o1 * b1 - o2 * b2; out = in * a0 + z1;
i2 = i1; z1 = a1 * in + z2 + b1 * out;
o2 = o1; z2 = a2 * in + b2 * out;
i1 = in; dst[n] = out;
o1 = dst[n] = out;
} }
b->i1 = i1; b->z1 = z1;
b->i2 = i2; b->z2 = z2;
b->o1 = o1;
b->o2 = o2;
} }
static int filter_channels(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs) static int filter_channels(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)