avfilter: add asubcut filter

6 files changed, 103 insertions, 20 deletions

diff --git a/Changelog b/Changelog
index ebb1727875..32eb71608a 100644
--- a/Changelog
+++ b/Changelog
@@ -48,6 +48,7 @@ version <next>:
 - speechnorm filter
 - SpeedHQ encoder
 - asupercut filter
+- asubcut filter
 
 
 version 4.3:
diff --git a/doc/filters.texi b/doc/filters.texi
index 537f8fee6f..6200590f84 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -2662,6 +2662,32 @@ Default value is 20.
 
 This filter supports the all above options as @ref{commands}.
 
+@section asubcut
+Cut subwoofer frequencies.
+
+This filter allows to set custom, steeper
+roll off than highpass filter, and thus is able to more attenuate
+frequency content in stop-band.
+
+The filter accepts the following options:
+
+@table @option
+@item cutoff
+Set cutoff frequency in Hertz. Allowed range is 2 to 200.
+Default value is 20.
+
+@item order
+Set filter order. Available values are from 3 to 20.
+Default value is 10.
+
+@item level
+Set input gain level. Allowed range is from 0 to 1. Default value is 1.
+@end table
+
+@subsection Commands
+
+This filter supports the all above options as @ref{commands}.
+
 @section asupercut
 Cut super frequencies.
 
@@ -2675,6 +2701,9 @@ Default value is 20000.
 @item order
 Set filter order. Available values are from 3 to 20.
 Default value is 10.
+
+@item level
+Set input gain level. Allowed range is from 0 to 1. Default value is 1.
 @end table
 
 @subsection Commands
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index cff9402989..03998dc064 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -90,6 +90,7 @@ OBJS-$(CONFIG_ASR_FILTER)                    += af_asr.o
 OBJS-$(CONFIG_ASTATS_FILTER)                 += af_astats.o
 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-$(CONFIG_ATEMPO_FILTER)                 += af_atempo.o
 OBJS-$(CONFIG_ATRIM_FILTER)                  += trim.o
diff --git a/libavfilter/af_asupercut.c b/libavfilter/af_asupercut.c
index ef241405d8..6d0a2b79a9 100644
--- a/libavfilter/af_asupercut.c
+++ b/libavfilter/af_asupercut.c
@@ -32,6 +32,7 @@ typedef struct ASuperCutContext {
     const AVClass *class;
 
     double cutoff;
+    double level;
     int order;
 
     int filter_count;
@@ -95,27 +96,52 @@ static int get_coeffs(AVFilterContext *ctx)
     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);
+    if (!strcmp(ctx->filter->name, "asubcut")) {
+        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.;
-    }
+            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);
 
-    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 (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.;
+        }
 
-        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;
+        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;
+        }
     }
 
     return 0;
@@ -135,6 +161,7 @@ static int filter_channels_## name(AVFilterContext *ctx, void *arg, \
     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];      \
@@ -150,7 +177,7 @@ static int filter_channels_## name(AVFilterContext *ctx, void *arg, \
             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];                     \
+                type sin = b ? dst[n] : src[n] * level;             \
                 type sout = sin * b0 + w[0];                        \
                                                                     \
                 w[0] = b1 * sin + w[1] + a1 * sout;                 \
@@ -240,6 +267,7 @@ static av_cold void uninit(AVFilterContext *ctx)
 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 }
 };
 
@@ -276,3 +304,26 @@ AVFilter ff_af_asupercut = {
     .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,
+};
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 83f434bc27..d0fb7bfe9d 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -83,6 +83,7 @@ extern AVFilter ff_af_asr;
 extern AVFilter ff_af_astats;
 extern AVFilter ff_af_astreamselect;
 extern AVFilter ff_af_asubboost;
+extern AVFilter ff_af_asubcut;
 extern AVFilter ff_af_asupercut;
 extern AVFilter ff_af_atempo;
 extern AVFilter ff_af_atrim;
diff --git a/libavfilter/version.h b/libavfilter/version.h
index bd20eaee73..dca46b8e62 100644
--- a/libavfilter/version.h
+++ b/libavfilter/version.h
@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR   7
-#define LIBAVFILTER_VERSION_MINOR  91
+#define LIBAVFILTER_VERSION_MINOR  92
 #define LIBAVFILTER_VERSION_MICRO 100