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af_asupercut.c
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/*
* 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"
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 const enum AVSampleFormat sample_fmts[] = {
AV_SAMPLE_FMT_FLTP, AV_SAMPLE_FMT_DBLP, AV_SAMPLE_FMT_NONE
};
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->ch_layout.nb_channels * jobnr) / nb_jobs; \
const int end = (in->ch_layout.nb_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;
ff_filter_execute(ctx, s->filter_channels, &td, NULL,
FFMIN(inlink->ch_layout.nb_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,
},
};
const AVFilter ff_af_asupercut = {
.name = "asupercut",
.description = NULL_IF_CONFIG_SMALL("Cut super frequencies."),
.priv_size = sizeof(ASuperCutContext),
.priv_class = &asupercut_class,
.uninit = uninit,
FILTER_INPUTS(inputs),
FILTER_OUTPUTS(ff_audio_default_filterpad),
FILTER_SAMPLEFMTS_ARRAY(sample_fmts),
.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);
const AVFilter ff_af_asubcut = {
.name = "asubcut",
.description = NULL_IF_CONFIG_SMALL("Cut subwoofer frequencies."),
.priv_size = sizeof(ASuperCutContext),
.priv_class = &asubcut_class,
.uninit = uninit,
FILTER_INPUTS(inputs),
FILTER_OUTPUTS(ff_audio_default_filterpad),
FILTER_SAMPLEFMTS_ARRAY(sample_fmts),
.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 }
};
AVFILTER_DEFINE_CLASS_EXT(asuperpass_asuperstop, "asuperpass/asuperstop",
asuperpass_asuperstop_options);
const AVFilter ff_af_asuperpass = {
.name = "asuperpass",
.description = NULL_IF_CONFIG_SMALL("Apply high order Butterworth band-pass filter."),
.priv_class = &asuperpass_asuperstop_class,
.priv_size = sizeof(ASuperCutContext),
.uninit = uninit,
FILTER_INPUTS(inputs),
FILTER_OUTPUTS(ff_audio_default_filterpad),
FILTER_SAMPLEFMTS_ARRAY(sample_fmts),
.process_command = process_command,
.flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC |
AVFILTER_FLAG_SLICE_THREADS,
};
const AVFilter ff_af_asuperstop = {
.name = "asuperstop",
.description = NULL_IF_CONFIG_SMALL("Apply high order Butterworth band-stop filter."),
.priv_class = &asuperpass_asuperstop_class,
.priv_size = sizeof(ASuperCutContext),
.uninit = uninit,
FILTER_INPUTS(inputs),
FILTER_OUTPUTS(ff_audio_default_filterpad),
FILTER_SAMPLEFMTS_ARRAY(sample_fmts),
.process_command = process_command,
.flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC |
AVFILTER_FLAG_SLICE_THREADS,
};