avfilter: add asuperpass and asuperstop filter

Changelog

@@ -52,6 +52,7 @@ version <next>:
 - Microsoft Paint (MSP) version 2 decoder
 - Microsoft Paint (MSP) demuxer
 - AV1 monochrome encoding support via libaom >= 2.0.1
+- asuperpass and asuperstop filter
 
 
 version 4.3:

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}.
 
+@section asuperpass
+Apply high order Butterworth band-pass filter.
+
+The filter accepts the following options:
+
+@table @option
+@item centerf
+Set center frequency in Hertz. Allowed range is 2 to 999999.
+Default value is 1000.
+
+@item order
+Set filter order. Available values are from 4 to 20.
+Default value is 4.
+
+@item qfactor
+Set Q-factor. Allowed range is from 0.01 to 100. Default value is 1.
+
+@item level
+Set input gain level. Allowed range is from 0 to 2. Default value is 1.
+@end table
+
+@subsection Commands
+
+This filter supports the all above options as @ref{commands}.
+
+@section asuperstop
+Apply high order Butterworth band-stop filter.
+
+The filter accepts the following options:
+
+@table @option
+@item centerf
+Set center frequency in Hertz. Allowed range is 2 to 999999.
+Default value is 1000.
+
+@item order
+Set filter order. Available values are from 4 to 20.
+Default value is 4.
+
+@item qfactor
+Set Q-factor. Allowed range is from 0.01 to 100. Default value is 1.
+
+@item level
+Set input gain level. Allowed range is from 0 to 2. Default value is 1.
+@end table
+
+@subsection Commands
+
+This filter supports the all above options as @ref{commands}.
+
 @section atempo
 
 Adjust audio tempo.

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_ATRIM_FILTER)                  += trim.o
 OBJS-$(CONFIG_AXCORRELATE_FILTER)            += af_axcorrelate.o

libavfilter/af_asupercut.c

 /*
+ * 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,
+};

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_atrim;
 extern AVFilter ff_af_axcorrelate;

libavfilter/version.h

@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR   7
-#define LIBAVFILTER_VERSION_MINOR  92
+#define LIBAVFILTER_VERSION_MINOR  93
 #define LIBAVFILTER_VERSION_MICRO 100