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avfilter/af_acrossover: improve filter output

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Makes sum always flat. Also faster.
This commit is contained in:
Paul B Mahol 2019-04-14 19:03:39 +02:00
parent 616e9b5cff
commit 270068b5af
1 changed files with 19 additions and 39 deletions
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52
libavfilter/af_acrossover.c
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@ -47,7 +47,6 @@ typedef struct BiquadContext {
typedef struct CrossoverChannel {
BiquadContext lp[MAX_BANDS][4];
BiquadContext hp[MAX_BANDS][4];
} CrossoverChannel;
typedef struct AudioCrossoverContext {
@ -131,30 +130,16 @@ static av_cold int init(AVFilterContext *ctx)
return ret;
}
static void set_lp(BiquadContext *b, float fc, float q, float sr)
static void set_lp(BiquadContext *b, double fc, double q, double sr)
{
double omega = (2.0 * M_PI * fc / sr);
double omega = 2.0 * M_PI * fc / sr;
double sn = sin(omega);
double cs = cos(omega);
double alpha = (sn / (2 * q));
double inv = (1.0 / (1.0 + alpha));
b->a2 = b->a0 = (inv * (1.0 - cs) * 0.5);
b->a1 = b->a0 + b->a0;
b->b1 = -2. * cs * inv;
b->b2 = (1. - alpha) * inv;
}
static void set_hp(BiquadContext *b, float fc, float q, float sr)
{
double omega = 2 * M_PI * fc / sr;
double sn = sin(omega);
double cs = cos(omega);
double alpha = sn / (2 * q);
double alpha = sn / (2. * q);
double inv = 1.0 / (1.0 + alpha);
b->a0 = inv * (1. + cs) / 2.;
b->a1 = -2. * b->a0;
b->a0 = (1. - cs) * 0.5 * inv;
b->a1 = (1. - cs) * inv;
b->a2 = b->a0;
b->b1 = -2. * cs * inv;
b->b2 = (1. - alpha) * inv;
@ -189,18 +174,13 @@ static int config_input(AVFilterLink *inlink)
for (ch = 0; ch < inlink->channels; ch++) {
for (band = 0; band <= s->nb_splits; band++) {
set_lp(&s->xover[ch].lp[band][0], s->splits[band], q, sample_rate);
set_hp(&s->xover[ch].hp[band][0], s->splits[band], q, sample_rate);
if (s->order > 1) {
set_lp(&s->xover[ch].lp[band][1], s->splits[band], 1.34, sample_rate);
set_hp(&s->xover[ch].hp[band][1], s->splits[band], 1.34, sample_rate);
set_lp(&s->xover[ch].lp[band][2], s->splits[band], q, sample_rate);
set_hp(&s->xover[ch].hp[band][2], s->splits[band], q, sample_rate);
set_lp(&s->xover[ch].lp[band][3], s->splits[band], 1.34, sample_rate);
set_hp(&s->xover[ch].hp[band][3], s->splits[band], 1.34, sample_rate);
} else {
set_lp(&s->xover[ch].lp[band][1], s->splits[band], q, sample_rate);
set_hp(&s->xover[ch].hp[band][1], s->splits[band], q, sample_rate);
}
}
}
@ -275,23 +255,23 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
const double *src = (const double *)in->extended_data[ch];
CrossoverChannel *xover = &s->xover[ch];
for (i = 0; i < in->nb_samples; i++) {
double sample = src[i], lo, hi;
for (band = 0; band < ctx->nb_outputs; band++) {
double *dst = (double *)frames[band]->extended_data[ch];
for (i = 0; i < in->nb_samples; i++) {
dst[i] = src[i];
for (f = 0; f < s->filter_count; f++) {
if (band + 1 < ctx->nb_outputs) {
lo = sample;
for (f = 0; band + 1 < ctx->nb_outputs && f < s->filter_count; f++) {
BiquadContext *lp = &xover->lp[band][f];
dst[i] = biquad_process(lp, dst[i]);
lo = biquad_process(lp, lo);
}
if (band - 1 >= 0) {
BiquadContext *hp = &xover->hp[band - 1][f];
dst[i] = biquad_process(hp, dst[i]);
}
}
hi = sample - lo;
dst[i] = lo;
sample = hi;
}
}
}