From b607f193743be473d6d401fd89e1177192565e62 Mon Sep 17 00:00:00 2001 From: Paul B Mahol Date: Sun, 6 Dec 2020 22:48:12 +0100 Subject: avfilter: add asuperpass and asuperstop filter --- libavfilter/af_asupercut.c | 133 +++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 129 insertions(+), 4 deletions(-) (limited to 'libavfilter/af_asupercut.c') diff --git a/libavfilter/af_asupercut.c b/libavfilter/af_asupercut.c index 6d0a2b79a9..89f4cf0ed0 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, 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(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, 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(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, +}; -- cgit v1.2.3