avfilter: add dialogue enhance audio filter

Changelog

@@ -1,7 +1,8 @@
 Entries are sorted chronologically from oldest to youngest within each release,
 releases are sorted from youngest to oldest.
 
-version <next>:
+version 5.1:
+- dialogue enhance audio filter
 
 
 version 5.0:

doc/filters.texi

@@ -4182,6 +4182,34 @@ Default value is @var{o}.
 
 @end table
 
+@section dialoguenhance
+Enhance dialogue in stereo audio.
+
+This filter accepts stereo input and produce surround (3.0) channels output.
+The newly produced front center channel have enhanced speech dialogue originally
+available in both stereo channels.
+This filter outputs front left and front right channels same as available in stereo input.
+
+The filter accepts the following options:
+
+@table @option
+@item original
+Set the original center factor to keep in front center channel output.
+Allowed range is from 0 to 1. Default value is 1.
+
+@item enhance
+Set the dialogue enhance factor to put in front center channel output.
+Allowed range is from 0 to 3. Default value is 1.
+
+@item voice
+Set the voice detection factor.
+Allowed range is from 2 to 32. Default value is 2.
+@end table
+
+@subsection Commands
+
+This filter supports the all above options as @ref{commands}.
+
 @section drmeter
 Measure audio dynamic range.
 

libavfilter/Makefile

@@ -124,6 +124,7 @@ OBJS-$(CONFIG_CROSSFEED_FILTER)              += af_crossfeed.o
 OBJS-$(CONFIG_CRYSTALIZER_FILTER)            += af_crystalizer.o
 OBJS-$(CONFIG_DCSHIFT_FILTER)                += af_dcshift.o
 OBJS-$(CONFIG_DEESSER_FILTER)                += af_deesser.o
+OBJS-$(CONFIG_DIALOGUENHANCE_FILTER)         += af_dialoguenhance.o
 OBJS-$(CONFIG_DRMETER_FILTER)                += af_drmeter.o
 OBJS-$(CONFIG_DYNAUDNORM_FILTER)             += af_dynaudnorm.o
 OBJS-$(CONFIG_EARWAX_FILTER)                 += af_earwax.o

libavfilter/af_dialoguenhance.c

@@ -0,0 +1,407 @@
+/*
+ * Copyright (c) 2022 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/opt.h"
+#include "libavutil/tx.h"
+#include "audio.h"
+#include "avfilter.h"
+#include "filters.h"
+#include "internal.h"
+#include "window_func.h"
+
+#include <float.h>
+
+typedef struct AudioDialogueEnhancementContext {
+    const AVClass *class;
+
+    double original, enhance, voice;
+
+    int fft_size;
+    int overlap;
+
+    float *window;
+    float prev_vad;
+
+    AVFrame *in;
+    AVFrame *in_frame;
+    AVFrame *out_dist_frame;
+    AVFrame *windowed_frame;
+    AVFrame *windowed_out;
+    AVFrame *windowed_prev;
+    AVFrame *center_frame;
+
+    AVTXContext *tx_ctx[2], *itx_ctx;
+    av_tx_fn tx_fn, itx_fn;
+} AudioDialogueEnhanceContext;
+
+#define OFFSET(x) offsetof(AudioDialogueEnhanceContext, x)
+#define FLAGS AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_FILTERING_PARAM | AV_OPT_FLAG_RUNTIME_PARAM
+
+static const AVOption dialoguenhance_options[] = {
+    { "original", "set original center factor", OFFSET(original), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0, 1, FLAGS },
+    { "enhance",  "set dialogue enhance factor",OFFSET(enhance),  AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0, 3, FLAGS },
+    { "voice",    "set voice detection factor", OFFSET(voice),    AV_OPT_TYPE_DOUBLE, {.dbl=2}, 2,32, FLAGS },
+    {NULL}
+};
+
+AVFILTER_DEFINE_CLASS(dialoguenhance);
+
+static int query_formats(AVFilterContext *ctx)
+{
+    AVFilterFormats *formats = NULL;
+    AVFilterChannelLayouts *in_layout = NULL, *out_layout = NULL;
+    int ret;
+
+    if ((ret = ff_add_format                 (&formats, AV_SAMPLE_FMT_FLTP )) < 0 ||
+        (ret = ff_set_common_formats         (ctx     , formats            )) < 0 ||
+        (ret = ff_add_channel_layout         (&in_layout , AV_CH_LAYOUT_STEREO)) < 0 ||
+        (ret = ff_channel_layouts_ref(in_layout, &ctx->inputs[0]->outcfg.channel_layouts)) < 0 ||
+        (ret = ff_add_channel_layout         (&out_layout , AV_CH_LAYOUT_SURROUND)) < 0 ||
+        (ret = ff_channel_layouts_ref(out_layout, &ctx->outputs[0]->incfg.channel_layouts)) < 0)
+        return ret;
+
+    return ff_set_common_all_samplerates(ctx);
+}
+
+static int config_input(AVFilterLink *inlink)
+{
+    AVFilterContext *ctx = inlink->dst;
+    AudioDialogueEnhanceContext *s = ctx->priv;
+    float scale = 1.f, iscale, overlap;
+    int ret;
+
+    s->fft_size = inlink->sample_rate > 100000 ? 8192 : inlink->sample_rate > 50000 ? 4096 : 2048;
+    s->overlap = s->fft_size / 4;
+
+    s->window = av_calloc(s->fft_size, sizeof(*s->window));
+    if (!s->window)
+        return AVERROR(ENOMEM);
+
+    s->in_frame       = ff_get_audio_buffer(inlink, s->fft_size * 4);
+    s->center_frame   = ff_get_audio_buffer(inlink, s->fft_size * 4);
+    s->out_dist_frame = ff_get_audio_buffer(inlink, s->fft_size * 4);
+    s->windowed_frame = ff_get_audio_buffer(inlink, s->fft_size * 4);
+    s->windowed_out   = ff_get_audio_buffer(inlink, s->fft_size * 4);
+    s->windowed_prev  = ff_get_audio_buffer(inlink, s->fft_size * 4);
+    if (!s->in_frame || !s->windowed_out || !s->windowed_prev ||
+        !s->out_dist_frame || !s->windowed_frame || !s->center_frame)
+        return AVERROR(ENOMEM);
+
+    generate_window_func(s->window, s->fft_size, WFUNC_SINE, &overlap);
+
+    iscale = 1.f / s->fft_size;
+
+    ret = av_tx_init(&s->tx_ctx[0], &s->tx_fn, AV_TX_FLOAT_RDFT, 0, s->fft_size, &scale, 0);
+    if (ret < 0)
+        return ret;
+
+    ret = av_tx_init(&s->tx_ctx[1], &s->tx_fn, AV_TX_FLOAT_RDFT, 0, s->fft_size, &scale, 0);
+    if (ret < 0)
+        return ret;
+
+    ret = av_tx_init(&s->itx_ctx, &s->itx_fn, AV_TX_FLOAT_RDFT, 1, s->fft_size, &iscale, 0);
+    if (ret < 0)
+        return ret;
+
+    return 0;
+}
+
+static void apply_window(AudioDialogueEnhanceContext *s,
+                         const float *in_frame, float *out_frame, const int add_to_out_frame)
+{
+    const float *window = s->window;
+
+    if (add_to_out_frame) {
+        for (int i = 0; i < s->fft_size; i++)
+            out_frame[i] += in_frame[i] * window[i];
+    } else {
+        for (int i = 0; i < s->fft_size; i++)
+            out_frame[i] = in_frame[i] * window[i];
+    }
+}
+
+static float sqrf(float x)
+{
+    return x * x;
+}
+
+static void get_centere(AVComplexFloat *left, AVComplexFloat *right,
+                        AVComplexFloat *center, int N)
+{
+    for (int i = 0; i < N; i++) {
+        const float l_re = left[i].re;
+        const float l_im = left[i].im;
+        const float r_re = right[i].re;
+        const float r_im = right[i].im;
+        const float a = 0.5f * (1.f - sqrtf((sqrf(l_re - r_re) + sqrf(l_im - r_im))/
+                                            (sqrf(l_re + r_re) + sqrf(l_im + r_im) + FLT_EPSILON)));
+
+        center[i].re = a * (l_re + r_re);
+        center[i].im = a * (l_im + r_im);
+    }
+}
+
+static float flux(float *curf, float *prevf, int N)
+{
+    AVComplexFloat *cur  = (AVComplexFloat *)curf;
+    AVComplexFloat *prev = (AVComplexFloat *)prevf;
+    float sum = 0.f;
+
+    for (int i = 0; i < N; i++) {
+        float c_re = cur[i].re;
+        float c_im = cur[i].im;
+        float p_re = prev[i].re;
+        float p_im = prev[i].im;
+
+        sum += sqrf(hypotf(c_re, c_im) - hypotf(p_re, p_im));
+    }
+
+    return sum;
+}
+
+static float fluxlr(float *lf, float *lpf,
+                    float *rf, float *rpf,
+                    int N)
+{
+    AVComplexFloat *l  = (AVComplexFloat *)lf;
+    AVComplexFloat *lp = (AVComplexFloat *)lpf;
+    AVComplexFloat *r  = (AVComplexFloat *)rf;
+    AVComplexFloat *rp = (AVComplexFloat *)rpf;
+    float sum = 0.f;
+
+    for (int i = 0; i < N; i++) {
+        float c_re = l[i].re - r[i].re;
+        float c_im = l[i].im - r[i].im;
+        float p_re = lp[i].re - rp[i].re;
+        float p_im = lp[i].im - rp[i].im;
+
+        sum += sqrf(hypotf(c_re, c_im) - hypotf(p_re, p_im));
+    }
+
+    return sum;
+}
+
+static float calc_vad(float fc, float flr, float a)
+{
+    const float vad = a * (fc / (fc + flr) - 0.5f);
+
+    return av_clipf(vad, 0.f, 1.f);
+}
+
+static void get_final(float *c, float *l,
+                      float *r, float vad, int N,
+                      float original, float enhance)
+{
+    AVComplexFloat *center = (AVComplexFloat *)c;
+    AVComplexFloat *left   = (AVComplexFloat *)l;
+    AVComplexFloat *right  = (AVComplexFloat *)r;
+
+    for (int i = 0; i < N; i++) {
+        float cP = sqrf(center[i].re) + sqrf(center[i].im);
+        float lrP = sqrf(left[i].re - right[i].re) + sqrf(left[i].im - right[i].im);
+        float G = cP / (cP + lrP + FLT_EPSILON);
+        float re, im;
+
+        re = center[i].re * (original + vad * G * enhance);
+        im = center[i].im * (original + vad * G * enhance);
+
+        center[i].re = re;
+        center[i].im = im;
+    }
+}
+
+static int de_stereo(AVFilterContext *ctx, AVFrame *out)
+{
+    AudioDialogueEnhanceContext *s = ctx->priv;
+    float *center          = (float *)s->center_frame->extended_data[0];
+    float *center_prev     = (float *)s->center_frame->extended_data[1];
+    float *left_in         = (float *)s->in_frame->extended_data[0];
+    float *right_in        = (float *)s->in_frame->extended_data[1];
+    float *left_out        = (float *)s->out_dist_frame->extended_data[0];
+    float *right_out       = (float *)s->out_dist_frame->extended_data[1];
+    float *left_samples    = (float *)s->in->extended_data[0];
+    float *right_samples   = (float *)s->in->extended_data[1];
+    float *windowed_left   = (float *)s->windowed_frame->extended_data[0];
+    float *windowed_right  = (float *)s->windowed_frame->extended_data[1];
+    float *windowed_oleft  = (float *)s->windowed_out->extended_data[0];
+    float *windowed_oright = (float *)s->windowed_out->extended_data[1];
+    float *windowed_pleft  = (float *)s->windowed_prev->extended_data[0];
+    float *windowed_pright = (float *)s->windowed_prev->extended_data[1];
+    float *left_osamples   = (float *)out->extended_data[0];
+    float *right_osamples  = (float *)out->extended_data[1];
+    float *center_osamples = (float *)out->extended_data[2];
+    const int offset = s->fft_size - s->overlap;
+    float vad;
+
+    // shift in/out buffers
+    memmove(left_in, &left_in[s->overlap], offset * sizeof(float));
+    memmove(right_in, &right_in[s->overlap], offset * sizeof(float));
+    memmove(left_out, &left_out[s->overlap], offset * sizeof(float));
+    memmove(right_out, &right_out[s->overlap], offset * sizeof(float));
+
+    memcpy(&left_in[offset], left_samples, s->overlap * sizeof(float));
+    memcpy(&right_in[offset], right_samples, s->overlap * sizeof(float));
+    memset(&left_out[offset], 0, s->overlap * sizeof(float));
+    memset(&right_out[offset], 0, s->overlap * sizeof(float));
+
+    apply_window(s, left_in,  windowed_left,  0);
+    apply_window(s, right_in, windowed_right, 0);
+
+    s->tx_fn(s->tx_ctx[0], windowed_oleft,  windowed_left,  sizeof(float));
+    s->tx_fn(s->tx_ctx[1], windowed_oright, windowed_right, sizeof(float));
+
+    get_centere((AVComplexFloat *)windowed_oleft,
+                (AVComplexFloat *)windowed_oright,
+                (AVComplexFloat *)center,
+                s->fft_size / 2 + 1);
+
+    vad = calc_vad(flux(center, center_prev, s->fft_size / 2 + 1),
+                   fluxlr(windowed_oleft, windowed_pleft,
+                          windowed_oright, windowed_pright, s->fft_size / 2 + 1), s->voice);
+    vad = vad * 0.1 + 0.9 * s->prev_vad;
+    s->prev_vad = vad;
+
+    memcpy(center_prev,     center,          s->fft_size * sizeof(float));
+    memcpy(windowed_pleft,  windowed_oleft,  s->fft_size * sizeof(float));
+    memcpy(windowed_pright, windowed_oright, s->fft_size * sizeof(float));
+
+    get_final(center, windowed_oleft, windowed_oright, vad, s->fft_size / 2 + 1,
+              s->original, s->enhance);
+
+    s->itx_fn(s->itx_ctx, windowed_oleft, center, sizeof(float));
+
+    apply_window(s, windowed_oleft, left_out,  1);
+
+    for (int i = 0; i < s->overlap; i++) {
+        // 4 times overlap with squared hanning window results in 1.5 time increase in amplitude
+        if (!ctx->is_disabled)
+            center_osamples[i] = left_out[i] / 1.5f;
+        else
+            center_osamples[i] = 0.f;
+        left_osamples[i]  = left_in[i];
+        right_osamples[i] = right_in[i];
+    }
+
+    return 0;
+}
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *in)
+{
+    AVFilterContext *ctx = inlink->dst;
+    AVFilterLink *outlink = ctx->outputs[0];
+    AudioDialogueEnhanceContext *s = ctx->priv;
+    AVFrame *out;
+    int ret;
+
+    out = ff_get_audio_buffer(outlink, s->overlap);
+    if (!out) {
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+
+    s->in = in;
+    de_stereo(ctx, out);
+
+    out->pts = in->pts;
+    out->nb_samples = in->nb_samples;
+    ret = ff_filter_frame(outlink, out);
+fail:
+    av_frame_free(&in);
+    s->in = NULL;
+    return ret < 0 ? ret : 0;
+}
+
+static int activate(AVFilterContext *ctx)
+{
+    AVFilterLink *inlink = ctx->inputs[0];
+    AVFilterLink *outlink = ctx->outputs[0];
+    AudioDialogueEnhanceContext *s = ctx->priv;
+    AVFrame *in = NULL;
+    int ret = 0, status;
+    int64_t pts;
+
+    FF_FILTER_FORWARD_STATUS_BACK(outlink, inlink);
+
+    ret = ff_inlink_consume_samples(inlink, s->overlap, s->overlap, &in);
+    if (ret < 0)
+        return ret;
+
+    if (ret > 0) {
+        return filter_frame(inlink, in);
+    } else if (ff_inlink_acknowledge_status(inlink, &status, &pts)) {
+        ff_outlink_set_status(outlink, status, pts);
+        return 0;
+    } else {
+        if (ff_inlink_queued_samples(inlink) >= s->overlap) {
+            ff_filter_set_ready(ctx, 10);
+        } else if (ff_outlink_frame_wanted(outlink)) {
+            ff_inlink_request_frame(inlink);
+        }
+        return 0;
+    }
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    AudioDialogueEnhanceContext *s = ctx->priv;
+
+    av_freep(&s->window);
+
+    av_frame_free(&s->in_frame);
+    av_frame_free(&s->center_frame);
+    av_frame_free(&s->out_dist_frame);
+    av_frame_free(&s->windowed_frame);
+    av_frame_free(&s->windowed_out);
+    av_frame_free(&s->windowed_prev);
+
+    av_tx_uninit(&s->tx_ctx[0]);
+    av_tx_uninit(&s->tx_ctx[1]);
+    av_tx_uninit(&s->itx_ctx);
+}
+
+static const AVFilterPad inputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_AUDIO,
+        .config_props = config_input,
+    },
+};
+
+static const AVFilterPad outputs[] = {
+    {
+        .name = "default",
+        .type = AVMEDIA_TYPE_AUDIO,
+    },
+};
+
+const AVFilter ff_af_dialoguenhance = {
+    .name            = "dialoguenhance",
+    .description     = NULL_IF_CONFIG_SMALL("Audio Dialogue Enhancement."),
+    .priv_size       = sizeof(AudioDialogueEnhanceContext),
+    .priv_class      = &dialoguenhance_class,
+    .uninit          = uninit,
+    FILTER_INPUTS(inputs),
+    FILTER_OUTPUTS(outputs),
+    FILTER_QUERY_FUNC(query_formats),
+    .flags           = AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL,
+    .activate        = activate,
+    .process_command = ff_filter_process_command,
+};

libavfilter/allfilters.c

@@ -115,6 +115,7 @@ extern const AVFilter ff_af_crossfeed;
 extern const AVFilter ff_af_crystalizer;
 extern const AVFilter ff_af_dcshift;
 extern const AVFilter ff_af_deesser;
+extern const AVFilter ff_af_dialoguenhance;
 extern const AVFilter ff_af_drmeter;
 extern const AVFilter ff_af_dynaudnorm;
 extern const AVFilter ff_af_earwax;

libavfilter/version.h

@@ -30,8 +30,8 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR   8
-#define LIBAVFILTER_VERSION_MINOR  26
-#define LIBAVFILTER_VERSION_MICRO 101
+#define LIBAVFILTER_VERSION_MINOR  27
+#define LIBAVFILTER_VERSION_MICRO 100
 
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \