libavfilter/af_asupercut.c - manifest_repos/ffmpeg - Git at Google

 /*
  * 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
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */

 #include "libavutil/channel_layout.h"
 #include "libavutil/ffmath.h"
 #include "libavutil/opt.h"
 #include "avfilter.h"
 #include "audio.h"
 #include "formats.h"

 typedef struct BiquadCoeffs {
     double a1, a2;
     double b0, b1, b2;
 } BiquadCoeffs;

 typedef struct ASuperCutContext {
     const AVClass *class;

     double cutoff;
     double level;
     double qfactor;
     int order;

     int filter_count;
     int bypass;

     BiquadCoeffs coeffs[10];

     AVFrame *w;

     int (*filter_channels)(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs);
 } ASuperCutContext;

 static int query_formats(AVFilterContext *ctx)
 {
     AVFilterFormats *formats = NULL;
     AVFilterChannelLayouts *layouts = NULL;
     static const enum AVSampleFormat sample_fmts[] = {
         AV_SAMPLE_FMT_FLTP,
         AV_SAMPLE_FMT_DBLP,
         AV_SAMPLE_FMT_NONE
     };
     int ret;

     formats = ff_make_format_list(sample_fmts);
     if (!formats)
         return AVERROR(ENOMEM);
     ret = ff_set_common_formats(ctx, formats);
     if (ret < 0)
         return ret;

     layouts = ff_all_channel_counts();
     if (!layouts)
         return AVERROR(ENOMEM);

     ret = ff_set_common_channel_layouts(ctx, layouts);
     if (ret < 0)
         return ret;

     formats = ff_all_samplerates();
     return ff_set_common_samplerates(ctx, formats);
 }

 static void calc_q_factors(int n, double *q)
 {
     for (int i = 0; i < n / 2; i++)
         q[i] = 1. / (-2. * cos(M_PI * (2. * (i + 1) + n - 1.) / (2. * n)));
 }

 static int get_coeffs(AVFilterContext *ctx)
 {
     ASuperCutContext *s = ctx->priv;
     AVFilterLink *inlink = ctx->inputs[0];
     double w0 = s->cutoff / inlink->sample_rate;
     double K = tan(M_PI * w0);
     double q[10];

     s->bypass = w0 >= 0.5;
     if (s->bypass)
         return 0;

     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);

             coeffs->b0 = 2. / (2. + omega);
             coeffs->b1 = -coeffs->b0;
             coeffs->b2 = 0.;
             coeffs->a1 = -(omega - 2.) / (2. + omega);
             coeffs->a2 = 0.;
         }

         for (int b = (s->order & 1); b < s->filter_count; b++) {
             BiquadCoeffs *coeffs = &s->coeffs[b];
             const int idx = b - (s->order & 1);
             double norm = 1.0 / (1.0 + K / q[idx] + K * K);

             coeffs->b0 = norm;
             coeffs->b1 = -2.0 * coeffs->b0;
             coeffs->b2 = coeffs->b0;
             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, "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);

             coeffs->b0 = omega / (2. + omega);
             coeffs->b1 = coeffs->b0;
             coeffs->b2 = 0.;
             coeffs->a1 = -(omega - 2.) / (2. + omega);
             coeffs->a2 = 0.;
         }

         for (int b = (s->order & 1); b < s->filter_count; b++) {
             BiquadCoeffs *coeffs = &s->coeffs[b];
             const int idx = b - (s->order & 1);
             double norm = 1.0 / (1.0 + K / q[idx] + K * K);

             coeffs->b0 = K * K * norm;
             coeffs->b1 = 2.0 * coeffs->b0;
             coeffs->b2 = coeffs->b0;
             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;
 }

 typedef struct ThreadData {
     AVFrame *in, *out;
 } ThreadData;

 #define FILTER(name, type)                                          \
 static int filter_channels_## name(AVFilterContext *ctx, void *arg, \
                                    int jobnr, int nb_jobs)          \
 {                                                                   \
     ASuperCutContext *s = ctx->priv;                                \
     ThreadData *td = arg;                                           \
     AVFrame *out = td->out;                                         \
     AVFrame *in = td->in;                                           \
     const int start = (in->channels * jobnr) / nb_jobs;             \
     const int end = (in->channels * (jobnr+1)) / nb_jobs;           \
     const double level = s->level;                                  \
                                                                     \
     for (int ch = start; ch < end; ch++) {                          \
         const type *src = (const type *)in->extended_data[ch];      \
         type *dst = (type *)out->extended_data[ch];                 \
                                                                     \
         for (int b = 0; b < s->filter_count; b++) {                 \
             BiquadCoeffs *coeffs = &s->coeffs[b];                   \
             const type a1 = coeffs->a1;                             \
             const type a2 = coeffs->a2;                             \
             const type b0 = coeffs->b0;                             \
             const type b1 = coeffs->b1;                             \
             const type b2 = coeffs->b2;                             \
             type *w = ((type *)s->w->extended_data[ch]) + b * 2;    \
                                                                     \
             for (int n = 0; n < in->nb_samples; n++) {              \
                 type sin = b ? dst[n] : src[n] * level;             \
                 type sout = sin * b0 + w[0];                        \
                                                                     \
                 w[0] = b1 * sin + w[1] + a1 * sout;                 \
                 w[1] = b2 * sin + a2 * sout;                        \
                                                                     \
                 dst[n] = sout;                                      \
             }                                                       \
         }                                                           \
     }                                                               \
                                                                     \
     return 0;                                                       \
 }

 FILTER(fltp, float)
 FILTER(dblp, double)

 static int config_input(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;
     ASuperCutContext *s = ctx->priv;

     switch (inlink->format) {
     case AV_SAMPLE_FMT_FLTP: s->filter_channels = filter_channels_fltp; break;
     case AV_SAMPLE_FMT_DBLP: s->filter_channels = filter_channels_dblp; break;
     }

     s->w = ff_get_audio_buffer(inlink, 2 * 10);
     if (!s->w)
         return AVERROR(ENOMEM);

     return get_coeffs(ctx);
 }

 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
 {
     AVFilterContext *ctx = inlink->dst;
     ASuperCutContext *s = ctx->priv;
     AVFilterLink *outlink = ctx->outputs[0];
     ThreadData td;
     AVFrame *out;

     if (s->bypass)
         return ff_filter_frame(outlink, in);

     if (av_frame_is_writable(in)) {
         out = in;
     } else {
         out = ff_get_audio_buffer(outlink, in->nb_samples);
         if (!out) {
             av_frame_free(&in);
             return AVERROR(ENOMEM);
         }
         av_frame_copy_props(out, in);
     }

     td.in = in; td.out = out;
     ctx->internal->execute(ctx, s->filter_channels, &td, NULL, FFMIN(inlink->channels,
                                                                ff_filter_get_nb_threads(ctx)));

     if (out != in)
         av_frame_free(&in);
     return ff_filter_frame(outlink, out);
 }

 static int process_command(AVFilterContext *ctx, const char *cmd, const char *args,
                            char *res, int res_len, int flags)
 {
     int ret;

     ret = ff_filter_process_command(ctx, cmd, args, res, res_len, flags);
     if (ret < 0)
         return ret;

     return get_coeffs(ctx);
 }

 static av_cold void uninit(AVFilterContext *ctx)
 {
     ASuperCutContext *s = ctx->priv;

     av_frame_free(&s->w);
 }

 #define OFFSET(x) offsetof(ASuperCutContext, x)
 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_RUNTIME_PARAM

 static const AVOption asupercut_options[] = {
     { "cutoff", "set cutoff frequency", OFFSET(cutoff), AV_OPT_TYPE_DOUBLE, {.dbl=20000}, 20000, 192000, FLAGS },
     { "order",  "set filter order",     OFFSET(order),  AV_OPT_TYPE_INT,    {.i64=10},        3,     20, FLAGS },
     { "level",  "set input level",      OFFSET(level),  AV_OPT_TYPE_DOUBLE, {.dbl=1.},        0.,    1., FLAGS },
     { NULL }
 };

 AVFILTER_DEFINE_CLASS(asupercut);

 static const AVFilterPad inputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_AUDIO,
         .filter_frame = filter_frame,
         .config_props = config_input,
     },
     { NULL }
 };

 static const AVFilterPad outputs[] = {
     {
         .name = "default",
         .type = AVMEDIA_TYPE_AUDIO,
     },
     { NULL }
 };

 AVFilter ff_af_asupercut = {
     .name            = "asupercut",
     .description     = NULL_IF_CONFIG_SMALL("Cut super frequencies."),
     .query_formats   = query_formats,
     .priv_size       = sizeof(ASuperCutContext),
     .priv_class      = &asupercut_class,
     .uninit          = uninit,
     .inputs          = inputs,
     .outputs         = outputs,
     .process_command = process_command,
     .flags           = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC |
                        AVFILTER_FLAG_SLICE_THREADS,
 };

 static const AVOption asubcut_options[] = {
     { "cutoff", "set cutoff frequency", OFFSET(cutoff), AV_OPT_TYPE_DOUBLE, {.dbl=20},  2, 200, FLAGS },
     { "order",  "set filter order",     OFFSET(order),  AV_OPT_TYPE_INT,    {.i64=10},  3,  20, FLAGS },
     { "level",  "set input level",      OFFSET(level),  AV_OPT_TYPE_DOUBLE, {.dbl=1.}, 0.,  1., FLAGS },
     { NULL }
 };

 AVFILTER_DEFINE_CLASS(asubcut);

 AVFilter ff_af_asubcut = {
     .name            = "asubcut",
     .description     = NULL_IF_CONFIG_SMALL("Cut subwoofer frequencies."),
     .query_formats   = query_formats,
     .priv_size       = sizeof(ASuperCutContext),
     .priv_class      = &asubcut_class,
     .uninit          = uninit,
     .inputs          = inputs,
     .outputs         = outputs,
     .process_command = process_command,
     .flags           = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC |
                        AVFILTER_FLAG_SLICE_THREADS,
 };

 static const AVOption asuperpass_asuperstop_options[] = {
     { "centerf","set center frequency", OFFSET(cutoff), AV_OPT_TYPE_DOUBLE, {.dbl=1000}, 2, 999999, 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.},0.01,   100., FLAGS },
     { "level",  "set input level",      OFFSET(level),  AV_OPT_TYPE_DOUBLE, {.dbl=1.},   0.,    2., FLAGS },
     { NULL }
 };

 #define asuperpass_options asuperpass_asuperstop_options
 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,
 };

 #define asuperstop_options asuperpass_asuperstop_options
 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,
 };
	/*
	* 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
	* modify it under the terms of the GNU Lesser General Public
	* License as published by the Free Software Foundation; either
	* version 2.1 of the License, or (at your option) any later version.
	*
	* FFmpeg is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* Lesser General Public License for more details.
	*
	* You should have received a copy of the GNU Lesser General Public
	* License along with FFmpeg; if not, write to the Free Software
	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	*/

	#include "libavutil/channel_layout.h"
	#include "libavutil/ffmath.h"
	#include "libavutil/opt.h"
	#include "avfilter.h"
	#include "audio.h"
	#include "formats.h"

	typedef struct BiquadCoeffs {
	double a1, a2;
	double b0, b1, b2;
	} BiquadCoeffs;

	typedef struct ASuperCutContext {
	const AVClass *class;

	double cutoff;
	double level;
	double qfactor;
	int order;

	int filter_count;
	int bypass;

	BiquadCoeffs coeffs[10];

	AVFrame *w;

	int (filter_channels)(AVFilterContext ctx, void *arg, int jobnr, int nb_jobs);
	} ASuperCutContext;

	static int query_formats(AVFilterContext *ctx)
	{
	AVFilterFormats *formats = NULL;
	AVFilterChannelLayouts *layouts = NULL;
	static const enum AVSampleFormat sample_fmts[] = {
	AV_SAMPLE_FMT_FLTP,
	AV_SAMPLE_FMT_DBLP,
	AV_SAMPLE_FMT_NONE
	};
	int ret;

	formats = ff_make_format_list(sample_fmts);
	if (!formats)
	return AVERROR(ENOMEM);
	ret = ff_set_common_formats(ctx, formats);
	if (ret < 0)
	return ret;

	layouts = ff_all_channel_counts();
	if (!layouts)
	return AVERROR(ENOMEM);

	ret = ff_set_common_channel_layouts(ctx, layouts);
	if (ret < 0)
	return ret;

	formats = ff_all_samplerates();
	return ff_set_common_samplerates(ctx, formats);
	}

	static void calc_q_factors(int n, double *q)
	{
	for (int i = 0; i < n / 2; i++)
	q[i] = 1. / (-2. * cos(M_PI * (2. * (i + 1) + n - 1.) / (2. * n)));
	}

	static int get_coeffs(AVFilterContext *ctx)
	{
	ASuperCutContext *s = ctx->priv;
	AVFilterLink *inlink = ctx->inputs[0];
	double w0 = s->cutoff / inlink->sample_rate;
	double K = tan(M_PI * w0);
	double q[10];

	s->bypass = w0 >= 0.5;
	if (s->bypass)
	return 0;

	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);

	coeffs->b0 = 2. / (2. + omega);
	coeffs->b1 = -coeffs->b0;
	coeffs->b2 = 0.;
	coeffs->a1 = -(omega - 2.) / (2. + omega);
	coeffs->a2 = 0.;
	}

	for (int b = (s->order & 1); b < s->filter_count; b++) {
	BiquadCoeffs *coeffs = &s->coeffs[b];
	const int idx = b - (s->order & 1);
	double norm = 1.0 / (1.0 + K / q[idx] + K * K);

	coeffs->b0 = norm;
	coeffs->b1 = -2.0 * coeffs->b0;
	coeffs->b2 = coeffs->b0;
	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, "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);

	coeffs->b0 = omega / (2. + omega);
	coeffs->b1 = coeffs->b0;
	coeffs->b2 = 0.;
	coeffs->a1 = -(omega - 2.) / (2. + omega);
	coeffs->a2 = 0.;
	}

	for (int b = (s->order & 1); b < s->filter_count; b++) {
	BiquadCoeffs *coeffs = &s->coeffs[b];
	const int idx = b - (s->order & 1);
	double norm = 1.0 / (1.0 + K / q[idx] + K * K);

	coeffs->b0 = K * K * norm;
	coeffs->b1 = 2.0 * coeffs->b0;
	coeffs->b2 = coeffs->b0;
	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;
	}

	typedef struct ThreadData {
	AVFrame in, out;
	} ThreadData;

	#define FILTER(name, type) \
	static int filter_channels_## name(AVFilterContext ctx, void arg, \
	int jobnr, int nb_jobs) \
	{ \
	ASuperCutContext *s = ctx->priv; \
	ThreadData *td = arg; \
	AVFrame *out = td->out; \
	AVFrame *in = td->in; \
	const int start = (in->channels * jobnr) / nb_jobs; \
	const int end = (in->channels * (jobnr+1)) / nb_jobs; \
	const double level = s->level; \
	\
	for (int ch = start; ch < end; ch++) { \
	const type src = (const type )in->extended_data[ch]; \
	type dst = (type )out->extended_data[ch]; \
	\
	for (int b = 0; b < s->filter_count; b++) { \
	BiquadCoeffs *coeffs = &s->coeffs[b]; \
	const type a1 = coeffs->a1; \
	const type a2 = coeffs->a2; \
	const type b0 = coeffs->b0; \
	const type b1 = coeffs->b1; \
	const type b2 = coeffs->b2; \
	type w = ((type )s->w->extended_data[ch]) + b * 2; \
	\
	for (int n = 0; n < in->nb_samples; n++) { \
	type sin = b ? dst[n] : src[n] * level; \
	type sout = sin * b0 + w[0]; \
	\
	w[0] = b1 * sin + w[1] + a1 * sout; \
	w[1] = b2 * sin + a2 * sout; \
	\
	dst[n] = sout; \
	} \
	} \
	} \
	\
	return 0; \
	}

	FILTER(fltp, float)
	FILTER(dblp, double)

	static int config_input(AVFilterLink *inlink)
	{
	AVFilterContext *ctx = inlink->dst;
	ASuperCutContext *s = ctx->priv;

	switch (inlink->format) {
	case AV_SAMPLE_FMT_FLTP: s->filter_channels = filter_channels_fltp; break;
	case AV_SAMPLE_FMT_DBLP: s->filter_channels = filter_channels_dblp; break;
	}

	s->w = ff_get_audio_buffer(inlink, 2 * 10);
	if (!s->w)
	return AVERROR(ENOMEM);

	return get_coeffs(ctx);
	}

	static int filter_frame(AVFilterLink inlink, AVFrame in)
	{
	AVFilterContext *ctx = inlink->dst;
	ASuperCutContext *s = ctx->priv;
	AVFilterLink *outlink = ctx->outputs[0];
	ThreadData td;
	AVFrame *out;

	if (s->bypass)
	return ff_filter_frame(outlink, in);

	if (av_frame_is_writable(in)) {
	out = in;
	} else {
	out = ff_get_audio_buffer(outlink, in->nb_samples);
	if (!out) {
	av_frame_free(&in);
	return AVERROR(ENOMEM);
	}
	av_frame_copy_props(out, in);
	}

	td.in = in; td.out = out;
	ctx->internal->execute(ctx, s->filter_channels, &td, NULL, FFMIN(inlink->channels,
	ff_filter_get_nb_threads(ctx)));

	if (out != in)
	av_frame_free(&in);
	return ff_filter_frame(outlink, out);
	}

	static int process_command(AVFilterContext ctx, const char cmd, const char *args,
	char *res, int res_len, int flags)
	{
	int ret;

	ret = ff_filter_process_command(ctx, cmd, args, res, res_len, flags);
	if (ret < 0)
	return ret;

	return get_coeffs(ctx);
	}

	static av_cold void uninit(AVFilterContext *ctx)
	{
	ASuperCutContext *s = ctx->priv;

	av_frame_free(&s->w);
	}

	#define OFFSET(x) offsetof(ASuperCutContext, x)
	#define FLAGS AV_OPT_FLAG_AUDIO_PARAM\|AV_OPT_FLAG_FILTERING_PARAM\|AV_OPT_FLAG_RUNTIME_PARAM

	static const AVOption asupercut_options[] = {
	{ "cutoff", "set cutoff frequency", OFFSET(cutoff), AV_OPT_TYPE_DOUBLE, {.dbl=20000}, 20000, 192000, FLAGS },
	{ "order", "set filter order", OFFSET(order), AV_OPT_TYPE_INT, {.i64=10}, 3, 20, FLAGS },
	{ "level", "set input level", OFFSET(level), AV_OPT_TYPE_DOUBLE, {.dbl=1.}, 0., 1., FLAGS },
	{ NULL }
	};

	AVFILTER_DEFINE_CLASS(asupercut);

	static const AVFilterPad inputs[] = {
	{
	.name = "default",
	.type = AVMEDIA_TYPE_AUDIO,
	.filter_frame = filter_frame,
	.config_props = config_input,
	},
	{ NULL }
	};

	static const AVFilterPad outputs[] = {
	{
	.name = "default",
	.type = AVMEDIA_TYPE_AUDIO,
	},
	{ NULL }
	};

	AVFilter ff_af_asupercut = {
	.name = "asupercut",
	.description = NULL_IF_CONFIG_SMALL("Cut super frequencies."),
	.query_formats = query_formats,
	.priv_size = sizeof(ASuperCutContext),
	.priv_class = &asupercut_class,
	.uninit = uninit,
	.inputs = inputs,
	.outputs = outputs,
	.process_command = process_command,
	.flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC \|
	AVFILTER_FLAG_SLICE_THREADS,
	};

	static const AVOption asubcut_options[] = {
	{ "cutoff", "set cutoff frequency", OFFSET(cutoff), AV_OPT_TYPE_DOUBLE, {.dbl=20}, 2, 200, FLAGS },
	{ "order", "set filter order", OFFSET(order), AV_OPT_TYPE_INT, {.i64=10}, 3, 20, FLAGS },
	{ "level", "set input level", OFFSET(level), AV_OPT_TYPE_DOUBLE, {.dbl=1.}, 0., 1., FLAGS },
	{ NULL }
	};

	AVFILTER_DEFINE_CLASS(asubcut);

	AVFilter ff_af_asubcut = {
	.name = "asubcut",
	.description = NULL_IF_CONFIG_SMALL("Cut subwoofer frequencies."),
	.query_formats = query_formats,
	.priv_size = sizeof(ASuperCutContext),
	.priv_class = &asubcut_class,
	.uninit = uninit,
	.inputs = inputs,
	.outputs = outputs,
	.process_command = process_command,
	.flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC \|
	AVFILTER_FLAG_SLICE_THREADS,
	};

	static const AVOption asuperpass_asuperstop_options[] = {
	{ "centerf","set center frequency", OFFSET(cutoff), AV_OPT_TYPE_DOUBLE, {.dbl=1000}, 2, 999999, 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.},0.01, 100., FLAGS },
	{ "level", "set input level", OFFSET(level), AV_OPT_TYPE_DOUBLE, {.dbl=1.}, 0., 2., FLAGS },
	{ NULL }
	};

	#define asuperpass_options asuperpass_asuperstop_options
	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,
	};

	#define asuperstop_options asuperpass_asuperstop_options
	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,
	};