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[FFmpeg-devel] avfilter: add frequency and phase shift filters

Message ID 20201017204557.25635-1-onemda@gmail.com
State Superseded
Headers show
Series [FFmpeg-devel] avfilter: add frequency and phase shift filters
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Commit Message

Paul B Mahol Oct. 17, 2020, 8:45 p.m. UTC
Signed-off-by: Paul B Mahol <onemda@gmail.com>
---
 doc/filters.texi            |  30 ++++
 libavfilter/Makefile        |   2 +
 libavfilter/af_afreqshift.c | 274 ++++++++++++++++++++++++++++++++++++
 libavfilter/allfilters.c    |   2 +
 4 files changed, 308 insertions(+)
 create mode 100644 libavfilter/af_afreqshift.c

Comments

Zane van Iperen Oct. 18, 2020, 2:24 a.m. UTC | #1
On 18/10/20 6:45 am, Paul B Mahol wrote:
> 
> Signed-off-by: Paul B Mahol <onemda@gmail.com>
> ---
>   doc/filters.texi            |  30 ++++
>   libavfilter/Makefile        |   2 +
>   libavfilter/af_afreqshift.c | 274 ++++++++++++++++++++++++++++++++++++
>   libavfilter/allfilters.c    |   2 +
>   4 files changed, 308 insertions(+)
>   create mode 100644 libavfilter/af_afreqshift.c

lgtm
diff mbox series

Patch

diff --git a/doc/filters.texi b/doc/filters.texi
index 50ef692077..428bf4ce92 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -1314,6 +1314,21 @@  Force the output to either unsigned 8-bit or signed 16-bit stereo
 aformat=sample_fmts=u8|s16:channel_layouts=stereo
 @end example
 
+@section afreqshift
+Apply frequency shift to input audio samples.
+
+The filter accepts the following options:
+
+@table @option
+@item shift
+Specify frequency shift. Allowed range is -INT_MAX to INT_MAX.
+Default value is 0.0.
+@end table
+
+@subsection Commands
+
+This filter supports the above option as @ref{commands}.
+
 @section agate
 
 A gate is mainly used to reduce lower parts of a signal. This kind of signal
@@ -2056,6 +2071,21 @@  It accepts the following values:
 @end table
 @end table
 
+@section aphaseshift
+Apply phase shift to input audio samples.
+
+The filter accepts the following options:
+
+@table @option
+@item shift
+Specify phase shift. Allowed range is -M_PI to M_PI.
+Default value is 0.0.
+@end table
+
+@subsection Commands
+
+This filter supports the above option as @ref{commands}.
+
 @section apulsator
 
 Audio pulsator is something between an autopanner and a tremolo.
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 2691612179..480e191987 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -50,6 +50,7 @@  OBJS-$(CONFIG_AFFTDN_FILTER)                 += af_afftdn.o
 OBJS-$(CONFIG_AFFTFILT_FILTER)               += af_afftfilt.o
 OBJS-$(CONFIG_AFIR_FILTER)                   += af_afir.o
 OBJS-$(CONFIG_AFORMAT_FILTER)                += af_aformat.o
+OBJS-$(CONFIG_AFREQSHIFT_FILTER)             += af_afreqshift.o
 OBJS-$(CONFIG_AGATE_FILTER)                  += af_agate.o
 OBJS-$(CONFIG_AIIR_FILTER)                   += af_aiir.o
 OBJS-$(CONFIG_AINTEGRAL_FILTER)              += af_aderivative.o
@@ -69,6 +70,7 @@  OBJS-$(CONFIG_ANULL_FILTER)                  += af_anull.o
 OBJS-$(CONFIG_APAD_FILTER)                   += af_apad.o
 OBJS-$(CONFIG_APERMS_FILTER)                 += f_perms.o
 OBJS-$(CONFIG_APHASER_FILTER)                += af_aphaser.o generate_wave_table.o
+OBJS-$(CONFIG_APHASESHIFT_FILTER)            += af_afreqshift.o
 OBJS-$(CONFIG_APULSATOR_FILTER)              += af_apulsator.o
 OBJS-$(CONFIG_AREALTIME_FILTER)              += f_realtime.o
 OBJS-$(CONFIG_ARESAMPLE_FILTER)              += af_aresample.o
diff --git a/libavfilter/af_afreqshift.c b/libavfilter/af_afreqshift.c
new file mode 100644
index 0000000000..6173be5a61
--- /dev/null
+++ b/libavfilter/af_afreqshift.c
@@ -0,0 +1,274 @@ 
+/*
+ * 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 AFreqShift {
+    const AVClass *class;
+
+    double shift;
+
+    double c[12];
+
+    int64_t in_samples;
+
+    AVFrame *i, *o;
+
+    void (*filter_channel)(AVFilterContext *ctx,
+                           int nb_samples,
+                           int sample_rate,
+                           const double *src, double *dst,
+                           double *i, double *o);
+} AFreqShift;
+
+static int query_formats(AVFilterContext *ctx)
+{
+    AVFilterFormats *formats = NULL;
+    AVFilterChannelLayouts *layouts = NULL;
+    static const enum AVSampleFormat sample_fmts[] = {
+        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 const double poles[12] =
+{
+    0.3609, 2.7412, 11.1573, 44.7581, 179.6242, 798.4578,
+    1.2524, 5.5671, 22.3423, 89.6271, 364.7914, 2770.1114,
+};
+
+static void pfilter_channel(AVFilterContext *ctx,
+                            int nb_samples,
+                            int sample_rate,
+                            const double *src, double *dst,
+                            double *i, double *o)
+{
+    AFreqShift *s = ctx->priv;
+    double *c = s->c;
+    double shift = s->shift;
+    double cos_theta = cos(shift);
+    double sin_theta = sin(shift);
+
+    for (int n = 0; n < nb_samples; n++) {
+        double xn1 = src[n], xn2 = src[n];
+        double I, Q;
+
+        for (int j = 0; j < 6; j++) {
+            I = c[j] * (xn1 - i[j]) + o[j];
+            o[j] = xn1;
+            i[j] = I;
+            xn1 = I;
+        }
+
+        for (int j = 6; j < 12; j++) {
+            Q = c[j] * (xn2 - i[j]) + o[j];
+            o[j] = xn2;
+            i[j] = Q;
+            xn2 = Q;
+        }
+
+        dst[n] = I * cos_theta - Q * sin_theta;
+    }
+}
+
+static void ffilter_channel(AVFilterContext *ctx,
+                            int nb_samples,
+                            int sample_rate,
+                            const double *src, double *dst,
+                            double *i, double *o)
+{
+    AFreqShift *s = ctx->priv;
+    double *c = s->c;
+    double ts = 1. / sample_rate;
+    double shift = s->shift;
+    int64_t N = s->in_samples;
+
+    for (int n = 0; n < nb_samples; n++) {
+        double xn1 = src[n], xn2 = src[n];
+        double I, Q, theta;
+
+        for (int j = 0; j < 6; j++) {
+            I = c[j] * (xn1 - i[j]) + o[j];
+            o[j] = xn1;
+            i[j] = I;
+            xn1 = I;
+        }
+
+        for (int j = 6; j < 12; j++) {
+            Q = c[j] * (xn2 - i[j]) + o[j];
+            o[j] = xn2;
+            i[j] = Q;
+            xn2 = Q;
+        }
+
+        theta = 2. * M_PI * fmod(shift * (N + n) * ts, 1.);
+        dst[n] = I * cos(theta) - Q * sin(theta);
+    }
+}
+
+static int config_input(AVFilterLink *inlink)
+{
+    AVFilterContext *ctx = inlink->dst;
+    AFreqShift *s = ctx->priv;
+
+    for (int j = 0; j < 12; j++) {
+        double polefreq = poles[j] * 15.;
+        double rc = 1. / (2. * M_PI * polefreq);
+        double alpha = (1. / rc) * 0.5 * (1. / inlink->sample_rate);
+        double beta = (1. - alpha) / (1. + alpha);
+
+        s->c[j] = -beta;
+    }
+
+    s->i = ff_get_audio_buffer(inlink, 12);
+    s->o = ff_get_audio_buffer(inlink, 12);
+    if (!s->i || !s->o)
+        return AVERROR(ENOMEM);
+
+    if (!strcmp(ctx->filter->name, "afreqshift"))
+        s->filter_channel = ffilter_channel;
+    else
+        s->filter_channel = pfilter_channel;
+
+    return 0;
+}
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *in)
+{
+    AVFilterContext *ctx = inlink->dst;
+    AVFilterLink *outlink = ctx->outputs[0];
+    AFreqShift *s = ctx->priv;
+    AVFrame *out;
+
+    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);
+    }
+
+    for (int ch = 0; ch < in->channels; ch++) {
+        s->filter_channel(ctx, in->nb_samples,
+                          in->sample_rate,
+                          (const double *)in->extended_data[ch],
+                          (double *)out->extended_data[ch],
+                          (double *)s->i->extended_data[ch],
+                          (double *)s->o->extended_data[ch]);
+    }
+
+    s->in_samples += in->nb_samples;
+
+    if (out != in)
+        av_frame_free(&in);
+    return ff_filter_frame(outlink, out);
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    AFreqShift *s = ctx->priv;
+
+    av_frame_free(&s->i);
+    av_frame_free(&s->o);
+}
+
+#define OFFSET(x) offsetof(AFreqShift, x)
+#define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_RUNTIME_PARAM
+
+static const AVOption afreqshift_options[] = {
+    { "shift", "set frequency shift", OFFSET(shift), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -INT_MAX, INT_MAX, FLAGS },
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(afreqshift);
+
+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_afreqshift = {
+    .name            = "afreqshift",
+    .description     = NULL_IF_CONFIG_SMALL("Apply frequency shifting to input audio."),
+    .query_formats   = query_formats,
+    .priv_size       = sizeof(AFreqShift),
+    .priv_class      = &afreqshift_class,
+    .uninit          = uninit,
+    .inputs          = inputs,
+    .outputs         = outputs,
+    .process_command = ff_filter_process_command,
+};
+
+static const AVOption aphaseshift_options[] = {
+    { "shift", "set phase shift", OFFSET(shift), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -M_PI, M_PI, FLAGS },
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(aphaseshift);
+
+AVFilter ff_af_aphaseshift = {
+    .name            = "aphaseshift",
+    .description     = NULL_IF_CONFIG_SMALL("Apply phase shifting to input audio."),
+    .query_formats   = query_formats,
+    .priv_size       = sizeof(AFreqShift),
+    .priv_class      = &aphaseshift_class,
+    .uninit          = uninit,
+    .inputs          = inputs,
+    .outputs         = outputs,
+    .process_command = ff_filter_process_command,
+};
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 26a8e87b0b..a5ec6bd4ca 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -43,6 +43,7 @@  extern AVFilter ff_af_afftdn;
 extern AVFilter ff_af_afftfilt;
 extern AVFilter ff_af_afir;
 extern AVFilter ff_af_aformat;
+extern AVFilter ff_af_afreqshift;
 extern AVFilter ff_af_agate;
 extern AVFilter ff_af_aiir;
 extern AVFilter ff_af_aintegral;
@@ -62,6 +63,7 @@  extern AVFilter ff_af_anull;
 extern AVFilter ff_af_apad;
 extern AVFilter ff_af_aperms;
 extern AVFilter ff_af_aphaser;
+extern AVFilter ff_af_aphaseshift;
 extern AVFilter ff_af_apulsator;
 extern AVFilter ff_af_arealtime;
 extern AVFilter ff_af_aresample;