[FFmpeg-devel] [PATCH] avfilter: add asuperpass and asuperstop filter
Paul B Mahol
onemda at gmail.com
Mon Dec 7 00:53:58 EET 2020
Signed-off-by: Paul B Mahol <onemda at gmail.com>
---
doc/filters.texi | 50 ++++++++++++++
libavfilter/Makefile | 2 +
libavfilter/af_asupercut.c | 133 +++++++++++++++++++++++++++++++++++--
libavfilter/allfilters.c | 2 +
4 files changed, 183 insertions(+), 4 deletions(-)
diff --git a/doc/filters.texi b/doc/filters.texi
index 3a31f72d79..5519d90327 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -2733,6 +2733,56 @@ Set input gain level. Allowed range is from 0 to 1. Default value is 1.
This filter supports the all above options as @ref{commands}.
+ at section asuperpass
+Apply high order Butterworth band-pass filter.
+
+The filter accepts the following options:
+
+ at table @option
+ at item centerf
+Set center frequency in Hertz. Allowed range is 2 to 192000.
+Default value is 1000.
+
+ at item order
+Set filter order. Available values are from 4 to 20.
+Default value is 4.
+
+ at item qfactor
+Set Q-factor. Allowed range is from 0 to 999. Default value is 1.
+
+ at item level
+Set input gain level. Allowed range is from 0 to 1. Default value is 1.
+ at end table
+
+ at subsection Commands
+
+This filter supports the all above options as @ref{commands}.
+
+ at section asuperstop
+Apply high order Butterworth band-stop filter.
+
+The filter accepts the following options:
+
+ at table @option
+ at item centerf
+Set center frequency in Hertz. Allowed range is 2 to 192000.
+Default value is 1000.
+
+ at item order
+Set filter order. Available values are from 4 to 20.
+Default value is 4.
+
+ at item qfactor
+Set Q-factor. Allowed range is from 0 to 999. Default value is 1.
+
+ at item level
+Set input gain level. Allowed range is from 0 to 1. Default value is 1.
+ at end table
+
+ at subsection Commands
+
+This filter supports the all above options as @ref{commands}.
+
@section atempo
Adjust audio tempo.
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 77cd55688b..4a96e04999 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -92,6 +92,8 @@ OBJS-$(CONFIG_ASTREAMSELECT_FILTER) += f_streamselect.o framesync.o
OBJS-$(CONFIG_ASUBBOOST_FILTER) += af_asubboost.o
OBJS-$(CONFIG_ASUBCUT_FILTER) += af_asupercut.o
OBJS-$(CONFIG_ASUPERCUT_FILTER) += af_asupercut.o
+OBJS-$(CONFIG_ASUPERPASS_FILTER) += af_asupercut.o
+OBJS-$(CONFIG_ASUPERSTOP_FILTER) += af_asupercut.o
OBJS-$(CONFIG_ATEMPO_FILTER) += af_atempo.o
OBJS-$(CONFIG_ATILT_FILTER) += af_atilt.o
OBJS-$(CONFIG_ATRIM_FILTER) += trim.o
diff --git a/libavfilter/af_asupercut.c b/libavfilter/af_asupercut.c
index 6d0a2b79a9..48738ad083 100644
--- a/libavfilter/af_asupercut.c
+++ b/libavfilter/af_asupercut.c
@@ -1,4 +1,7 @@
/*
+ * Copyright (c) 2005 Boðaç Topaktaþ
+ * Copyright (c) 2020 Paul B Mahol
+ *
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
@@ -33,6 +36,7 @@ typedef struct ASuperCutContext {
double cutoff;
double level;
+ double qfactor;
int order;
int filter_count;
@@ -93,10 +97,11 @@ static int get_coeffs(AVFilterContext *ctx)
if (s->bypass)
return 0;
- s->filter_count = s->order / 2 + (s->order & 1);
- calc_q_factors(s->order, q);
-
if (!strcmp(ctx->filter->name, "asubcut")) {
+ s->filter_count = s->order / 2 + (s->order & 1);
+
+ calc_q_factors(s->order, q);
+
if (s->order & 1) {
BiquadCoeffs *coeffs = &s->coeffs[0];
double omega = 2. * tan(M_PI * w0);
@@ -119,7 +124,11 @@ static int get_coeffs(AVFilterContext *ctx)
coeffs->a1 = -2.0 * (K * K - 1.0) * norm;
coeffs->a2 = -(1.0 - K / q[idx] + K * K) * norm;
}
- } else {
+ } else if (!strcmp(ctx->filter->name, "asupercut")) {
+ s->filter_count = s->order / 2 + (s->order & 1);
+
+ calc_q_factors(s->order, q);
+
if (s->order & 1) {
BiquadCoeffs *coeffs = &s->coeffs[0];
double omega = 2. * tan(M_PI * w0);
@@ -142,6 +151,74 @@ static int get_coeffs(AVFilterContext *ctx)
coeffs->a1 = -2.0 * (K * K - 1.0) * norm;
coeffs->a2 = -(1.0 - K / q[idx] + K * K) * norm;
}
+ } else if (!strcmp(ctx->filter->name, "asuperpass")) {
+ double alpha, beta, gamma, theta;
+ double theta_0 = 2. * M_PI * (s->cutoff / inlink->sample_rate);
+ double d_E;
+
+ s->filter_count = s->order / 2;
+ d_E = (2. * tan(theta_0 / (2. * s->qfactor))) / sin(theta_0);
+
+ for (int b = 0; b < s->filter_count; b += 2) {
+ double D = 2. * sin(((b + 1) * M_PI) / (2. * s->filter_count));
+ double A = (1. + pow((d_E / 2.), 2)) / (D * d_E / 2.);
+ double d = sqrt((d_E * D) / (A + sqrt(A * A - 1.)));
+ double B = D * (d_E / 2.) / d;
+ double W = B + sqrt(B * B - 1.);
+
+ for (int j = 0; j < 2; j++) {
+ BiquadCoeffs *coeffs = &s->coeffs[b + j];
+
+ if (j == 1)
+ theta = 2. * atan(tan(theta_0 / 2.) / W);
+ else
+ theta = 2. * atan(W * tan(theta_0 / 2.));
+
+ beta = 0.5 * ((1. - (d / 2.) * sin(theta)) / (1. + (d / 2.) * sin(theta)));
+ gamma = (0.5 + beta) * cos(theta);
+ alpha = 0.5 * (0.5 - beta) * sqrt(1. + pow((W - (1. / W)) / d, 2.));
+
+ coeffs->a1 = 2. * gamma;
+ coeffs->a2 = -2. * beta;
+ coeffs->b0 = 2. * alpha;
+ coeffs->b1 = 0.;
+ coeffs->b2 = -2. * alpha;
+ }
+ }
+ } else if (!strcmp(ctx->filter->name, "asuperstop")) {
+ double alpha, beta, gamma, theta;
+ double theta_0 = 2. * M_PI * (s->cutoff / inlink->sample_rate);
+ double d_E;
+
+ s->filter_count = s->order / 2;
+ d_E = (2. * tan(theta_0 / (2. * s->qfactor))) / sin(theta_0);
+
+ for (int b = 0; b < s->filter_count; b += 2) {
+ double D = 2. * sin(((b + 1) * M_PI) / (2. * s->filter_count));
+ double A = (1. + pow((d_E / 2.), 2)) / (D * d_E / 2.);
+ double d = sqrt((d_E * D) / (A + sqrt(A * A - 1.)));
+ double B = D * (d_E / 2.) / d;
+ double W = B + sqrt(B * B - 1.);
+
+ for (int j = 0; j < 2; j++) {
+ BiquadCoeffs *coeffs = &s->coeffs[b + j];
+
+ if (j == 1)
+ theta = 2. * atan(tan(theta_0 / 2.) / W);
+ else
+ theta = 2. * atan(W * tan(theta_0 / 2.));
+
+ beta = 0.5 * ((1. - (d / 2.) * sin(theta)) / (1. + (d / 2.) * sin(theta)));
+ gamma = (0.5 + beta) * cos(theta);
+ alpha = 0.5 * (0.5 + beta) * ((1. - cos(theta)) / (1. - cos(theta_0)));
+
+ coeffs->a1 = 2. * gamma;
+ coeffs->a2 = -2. * beta;
+ coeffs->b0 = 2. * alpha;
+ coeffs->b1 = -4. * alpha * cos(theta_0);
+ coeffs->b2 = 2. * alpha;
+ }
+ }
}
return 0;
@@ -327,3 +404,51 @@ AVFilter ff_af_asubcut = {
.flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC |
AVFILTER_FLAG_SLICE_THREADS,
};
+
+static const AVOption asuperpass_options[] = {
+ { "centerf","set center frequency", OFFSET(cutoff), AV_OPT_TYPE_DOUBLE, {.dbl=1000}, 2, 192000, FLAGS },
+ { "order", "set filter order", OFFSET(order), AV_OPT_TYPE_INT, {.i64=4}, 4, 20, FLAGS },
+ { "qfactor","set Q-factor", OFFSET(qfactor),AV_OPT_TYPE_DOUBLE, {.dbl=1.}, 0., 999., FLAGS },
+ { "level", "set input level", OFFSET(level), AV_OPT_TYPE_DOUBLE, {.dbl=1.}, 0., 1., FLAGS },
+ { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(asuperpass);
+
+AVFilter ff_af_asuperpass = {
+ .name = "asuperpass",
+ .description = NULL_IF_CONFIG_SMALL("Apply high order Butterworth band-pass filter."),
+ .query_formats = query_formats,
+ .priv_size = sizeof(ASuperCutContext),
+ .priv_class = &asuperpass_class,
+ .uninit = uninit,
+ .inputs = inputs,
+ .outputs = outputs,
+ .process_command = process_command,
+ .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC |
+ AVFILTER_FLAG_SLICE_THREADS,
+};
+
+static const AVOption asuperstop_options[] = {
+ { "centerf","set center frequency", OFFSET(cutoff), AV_OPT_TYPE_DOUBLE, {.dbl=1000}, 2, 192000, FLAGS },
+ { "order", "set filter order", OFFSET(order), AV_OPT_TYPE_INT, {.i64=4}, 4, 20, FLAGS },
+ { "qfactor","set Q-factor", OFFSET(qfactor),AV_OPT_TYPE_DOUBLE, {.dbl=1.}, 0., 999., FLAGS },
+ { "level", "set input level", OFFSET(level), AV_OPT_TYPE_DOUBLE, {.dbl=1.}, 0., 1., FLAGS },
+ { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(asuperstop);
+
+AVFilter ff_af_asuperstop = {
+ .name = "asuperstop",
+ .description = NULL_IF_CONFIG_SMALL("Apply high order Butterworth band-stop filter."),
+ .query_formats = query_formats,
+ .priv_size = sizeof(ASuperCutContext),
+ .priv_class = &asuperstop_class,
+ .uninit = uninit,
+ .inputs = inputs,
+ .outputs = outputs,
+ .process_command = process_command,
+ .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC |
+ AVFILTER_FLAG_SLICE_THREADS,
+};
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index a7f8d9f864..e90fcfb3bb 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -85,6 +85,8 @@ extern AVFilter ff_af_astreamselect;
extern AVFilter ff_af_asubboost;
extern AVFilter ff_af_asubcut;
extern AVFilter ff_af_asupercut;
+extern AVFilter ff_af_asuperpass;
+extern AVFilter ff_af_asuperstop;
extern AVFilter ff_af_atempo;
extern AVFilter ff_af_atilt;
extern AVFilter ff_af_atrim;
--
2.17.1
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