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avfilter/af_biquads: add one-pole shelf filters by adding pole option

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pull/371/head
Paul B Mahol 4 years ago
parent 1a8e719f36
commit 69be00aa61
2 changed files with 58 additions and 12 deletions
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  1. 6
      doc/filters.texi
  2. 64
      libavfilter/af_biquads.c

6
doc/filters.texi
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@ -3149,6 +3149,9 @@ kHz
@item width, w
Determine how steep is the filter's shelf transition.
@item poles, p
Set number of poles. Default is 2.
@item mix, m
How much to use filtered signal in output. Default is 1.
Range is between 0 and 1.
@ -6050,6 +6053,9 @@ kHz
@item width, w
Determine how steep is the filter's shelf transition.
@item poles, p
Set number of poles. Default is 2.
@item mix, m
How much to use filtered signal in output. Default is 1.
Range is between 0 and 1.

64
libavfilter/af_biquads.c
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@ -514,22 +514,54 @@ static int config_filter(AVFilterLink *outlink, int reset)
case bass:
beta = sqrt((A * A + 1) - (A - 1) * (A - 1));
case lowshelf:
s->a0 = (A + 1) + (A - 1) * cos(w0) + beta * alpha;
s->a1 = -2 * ((A - 1) + (A + 1) * cos(w0));
s->a2 = (A + 1) + (A - 1) * cos(w0) - beta * alpha;
s->b0 = A * ((A + 1) - (A - 1) * cos(w0) + beta * alpha);
s->b1 = 2 * A * ((A - 1) - (A + 1) * cos(w0));
s->b2 = A * ((A + 1) - (A - 1) * cos(w0) - beta * alpha);
if (s->poles == 1) {
double A = ff_exp10(s->gain / 20);
double ro = -sin(w0 / 2. - M_PI_4 / (sin(w0 / 2. + M_PI_4)));
double n = (A + 1) / (A - 1);
double alpha1 = A == 1. ? 0. : n - FFSIGN(n) * sqrt(n * n - 1);
double beta0 = ((1 + A) + (1 - A) * alpha1) * 0.5;
double beta1 = ((1 - A) + (1 + A) * alpha1) * 0.5;
s->a0 = 1 + ro * alpha1;
s->a1 = -ro - alpha1;
s->a2 = 0;
s->b0 = beta0 + ro * beta1;
s->b1 = -beta1 - ro * beta0;
s->b2 = 0;
} else {
s->a0 = (A + 1) + (A - 1) * cos(w0) + beta * alpha;
s->a1 = -2 * ((A - 1) + (A + 1) * cos(w0));
s->a2 = (A + 1) + (A - 1) * cos(w0) - beta * alpha;
s->b0 = A * ((A + 1) - (A - 1) * cos(w0) + beta * alpha);
s->b1 = 2 * A * ((A - 1) - (A + 1) * cos(w0));
s->b2 = A * ((A + 1) - (A - 1) * cos(w0) - beta * alpha);
}
break;
case treble:
beta = sqrt((A * A + 1) - (A - 1) * (A - 1));
case highshelf:
s->a0 = (A + 1) - (A - 1) * cos(w0) + beta * alpha;
s->a1 = 2 * ((A - 1) - (A + 1) * cos(w0));
s->a2 = (A + 1) - (A - 1) * cos(w0) - beta * alpha;
s->b0 = A * ((A + 1) + (A - 1) * cos(w0) + beta * alpha);
s->b1 =-2 * A * ((A - 1) + (A + 1) * cos(w0));
s->b2 = A * ((A + 1) + (A - 1) * cos(w0) - beta * alpha);
if (s->poles == 1) {
double A = ff_exp10(s->gain / 20);
double ro = sin(w0 / 2. - M_PI_4 / (sin(w0 / 2. + M_PI_4)));
double n = (A + 1) / (A - 1);
double alpha1 = A == 1. ? 0. : n - FFSIGN(n) * sqrt(n * n - 1);
double beta0 = ((1 + A) + (1 - A) * alpha1) * 0.5;
double beta1 = ((1 - A) + (1 + A) * alpha1) * 0.5;
s->a0 = 1 + ro * alpha1;
s->a1 = ro + alpha1;
s->a2 = 0;
s->b0 = beta0 + ro * beta1;
s->b1 = beta1 + ro * beta0;
s->b2 = 0;
} else {
s->a0 = (A + 1) - (A - 1) * cos(w0) + beta * alpha;
s->a1 = 2 * ((A - 1) - (A + 1) * cos(w0));
s->a2 = (A + 1) - (A - 1) * cos(w0) - beta * alpha;
s->b0 = A * ((A + 1) + (A - 1) * cos(w0) + beta * alpha);
s->b1 =-2 * A * ((A - 1) + (A + 1) * cos(w0));
s->b2 = A * ((A + 1) + (A - 1) * cos(w0) - beta * alpha);
}
break;
case bandpass:
if (s->csg) {
@ -914,6 +946,8 @@ static const AVOption bass_options[] = {
{"w", "set shelf transition steep", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 99999, FLAGS},
{"gain", "set gain", OFFSET(gain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -900, 900, FLAGS},
{"g", "set gain", OFFSET(gain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -900, 900, FLAGS},
{"poles", "set number of poles", OFFSET(poles), AV_OPT_TYPE_INT, {.i64=2}, 1, 2, AF},
{"p", "set number of poles", OFFSET(poles), AV_OPT_TYPE_INT, {.i64=2}, 1, 2, AF},
{"mix", "set mix", OFFSET(mix), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0, 1, FLAGS},
{"m", "set mix", OFFSET(mix), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0, 1, FLAGS},
{"channels", "set channels to filter", OFFSET(channels), AV_OPT_TYPE_CHANNEL_LAYOUT, {.i64=-1}, INT64_MIN, INT64_MAX, FLAGS},
@ -953,6 +987,8 @@ static const AVOption treble_options[] = {
{"w", "set shelf transition steep", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 99999, FLAGS},
{"gain", "set gain", OFFSET(gain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -900, 900, FLAGS},
{"g", "set gain", OFFSET(gain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -900, 900, FLAGS},
{"poles", "set number of poles", OFFSET(poles), AV_OPT_TYPE_INT, {.i64=2}, 1, 2, AF},
{"p", "set number of poles", OFFSET(poles), AV_OPT_TYPE_INT, {.i64=2}, 1, 2, AF},
{"mix", "set mix", OFFSET(mix), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0, 1, FLAGS},
{"m", "set mix", OFFSET(mix), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0, 1, FLAGS},
{"channels", "set channels to filter", OFFSET(channels), AV_OPT_TYPE_CHANNEL_LAYOUT, {.i64=-1}, INT64_MIN, INT64_MAX, FLAGS},
@ -1184,6 +1220,8 @@ static const AVOption lowshelf_options[] = {
{"w", "set shelf transition steep", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 99999, FLAGS},
{"gain", "set gain", OFFSET(gain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -900, 900, FLAGS},
{"g", "set gain", OFFSET(gain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -900, 900, FLAGS},
{"poles", "set number of poles", OFFSET(poles), AV_OPT_TYPE_INT, {.i64=2}, 1, 2, AF},
{"p", "set number of poles", OFFSET(poles), AV_OPT_TYPE_INT, {.i64=2}, 1, 2, AF},
{"mix", "set mix", OFFSET(mix), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0, 1, FLAGS},
{"m", "set mix", OFFSET(mix), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0, 1, FLAGS},
{"channels", "set channels to filter", OFFSET(channels), AV_OPT_TYPE_CHANNEL_LAYOUT, {.i64=-1}, INT64_MIN, INT64_MAX, FLAGS},
@ -1223,6 +1261,8 @@ static const AVOption highshelf_options[] = {
{"w", "set shelf transition steep", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 99999, FLAGS},
{"gain", "set gain", OFFSET(gain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -900, 900, FLAGS},
{"g", "set gain", OFFSET(gain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -900, 900, FLAGS},
{"poles", "set number of poles", OFFSET(poles), AV_OPT_TYPE_INT, {.i64=2}, 1, 2, AF},
{"p", "set number of poles", OFFSET(poles), AV_OPT_TYPE_INT, {.i64=2}, 1, 2, AF},
{"mix", "set mix", OFFSET(mix), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0, 1, FLAGS},
{"m", "set mix", OFFSET(mix), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0, 1, FLAGS},
{"channels", "set channels to filter", OFFSET(channels), AV_OPT_TYPE_CHANNEL_LAYOUT, {.i64=-1}, INT64_MIN, INT64_MAX, FLAGS},

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