avfilter: add audio denoising (afftdn) filter

1 files changed, 1421 insertions, 0 deletions

diff --git a/libavfilter/af_afftdn.c b/libavfilter/af_afftdn.c
new file mode 100644
index 0000000000..082b77f632
--- /dev/null
+++ b/libavfilter/af_afftdn.c
@@ -0,0 +1,1421 @@
+/*
+ * Copyright (c) 2018 The FFmpeg Project
+ *
+ * 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 <float.h>
+
+#include "libavutil/audio_fifo.h"
+#include "libavutil/avstring.h"
+#include "libavutil/channel_layout.h"
+#include "libavutil/opt.h"
+#include "libavcodec/avfft.h"
+#include "avfilter.h"
+#include "audio.h"
+#include "formats.h"
+
+#define C       (M_LN10 * 0.1)
+#define RATIO    0.98
+#define RRATIO  (1.0 - RATIO)
+
+enum OutModes {
+    IN_MODE,
+    OUT_MODE,
+    NOISE_MODE,
+    NB_MODES
+};
+
+enum NoiseType {
+    WHITE_NOISE,
+    VINYL_NOISE,
+    SHELLAC_NOISE,
+    CUSTOM_NOISE,
+    NB_NOISE
+};
+
+typedef struct DeNoiseChannel {
+    int         band_noise[15];
+    double      noise_band_auto_var[15];
+    double      noise_band_sample[15];
+    double     *amt;
+    double     *band_amt;
+    double     *band_excit;
+    double     *gain;
+    double     *prior;
+    double     *prior_band_excit;
+    double     *clean_data;
+    double     *noisy_data;
+    double     *out_samples;
+    double     *spread_function;
+    double     *abs_var;
+    double     *rel_var;
+    double     *min_abs_var;
+    FFTComplex *fft_data;
+    FFTContext *fft, *ifft;
+
+    double      noise_band_norm[15];
+    double      noise_band_avr[15];
+    double      noise_band_avi[15];
+    double      noise_band_var[15];
+
+    double      sfm_threshold;
+    double      sfm_alpha;
+    double      sfm_results[3];
+    int         sfm_fail_flags[512];
+    int         sfm_fail_total;
+} DeNoiseChannel;
+
+typedef struct AudioFFTDeNoiseContext {
+    const AVClass *class;
+
+    float   noise_reduction;
+    float   noise_floor;
+    int     noise_type;
+    char   *band_noise_str;
+    float   residual_floor;
+    int     track_noise;
+    int     track_residual;
+    int     output_mode;
+
+    float   last_residual_floor;
+    float   last_noise_floor;
+    float   last_noise_reduction;
+    float   last_noise_balance;
+    int64_t block_count;
+
+    int64_t pts;
+    int     channels;
+    int     sample_noise;
+    int     sample_noise_start;
+    int     sample_noise_end;
+    float   sample_rate;
+    int     buffer_length;
+    int     fft_length;
+    int     fft_length2;
+    int     bin_count;
+    int     window_length;
+    int     sample_advance;
+    int     number_of_bands;
+
+    int     band_centre[15];
+
+    int    *bin2band;
+    double *window;
+    double *band_alpha;
+    double *band_beta;
+
+    DeNoiseChannel *dnch;
+
+    double  max_gain;
+    double  max_var;
+    double  gain_scale;
+    double  window_weight;
+    double  floor;
+    double  sample_floor;
+    double  auto_floor;
+
+    int     noise_band_edge[17];
+    int     noise_band_count;
+    double  matrix_a[25];
+    double  vector_b[5];
+    double  matrix_b[75];
+    double  matrix_c[75];
+
+    AVAudioFifo *fifo;
+} AudioFFTDeNoiseContext;
+
+#define OFFSET(x) offsetof(AudioFFTDeNoiseContext, x)
+#define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
+
+static const AVOption afftdn_options[] = {
+    { "nr", "set the noise reduction",    OFFSET(noise_reduction), AV_OPT_TYPE_FLOAT,  {.dbl = 12},          .01, 97, A },
+    { "nf", "set the noise floor",        OFFSET(noise_floor),     AV_OPT_TYPE_FLOAT,  {.dbl =-50},          -80,-20, A },
+    { "nt", "set the noise type",         OFFSET(noise_type),      AV_OPT_TYPE_INT,    {.i64 = WHITE_NOISE}, WHITE_NOISE, NB_NOISE-1, A, "type" },
+    {  "w", "white noise",                0,                       AV_OPT_TYPE_CONST,  {.i64 = WHITE_NOISE},   0,  0, A, "type" },
+    {  "v", "vinyl noise",                0,                       AV_OPT_TYPE_CONST,  {.i64 = VINYL_NOISE},   0,  0, A, "type" },
+    {  "s", "shellac noise",              0,                       AV_OPT_TYPE_CONST,  {.i64 = SHELLAC_NOISE}, 0,  0, A, "type" },
+    {  "c", "custom noise",               0,                       AV_OPT_TYPE_CONST,  {.i64 = CUSTOM_NOISE},  0,  0, A, "type" },
+    { "bn", "set the custom bands noise", OFFSET(band_noise_str),  AV_OPT_TYPE_STRING, {.str = 0},             0,  0, A },
+    { "rf", "set the residual floor",     OFFSET(residual_floor),  AV_OPT_TYPE_FLOAT,  {.dbl =-38},          -80,-20, A },
+    { "tn", "track noise",                OFFSET(track_noise),     AV_OPT_TYPE_BOOL,   {.i64 =  0},            0,  1, A },
+    { "tr", "track residual",             OFFSET(track_residual),  AV_OPT_TYPE_BOOL,   {.i64 =  0},            0,  1, A },
+    { "om", "set output mode",            OFFSET(output_mode),     AV_OPT_TYPE_INT,    {.i64 = OUT_MODE},      0,  NB_MODES-1, A, "mode" },
+    {  "i", "input",                      0,                       AV_OPT_TYPE_CONST,  {.i64 = IN_MODE},       0,  0, A, "mode" },
+    {  "o", "output",                     0,                       AV_OPT_TYPE_CONST,  {.i64 = OUT_MODE},      0,  0, A, "mode" },
+    {  "n", "noise",                      0,                       AV_OPT_TYPE_CONST,  {.i64 = NOISE_MODE},    0,  0, A, "mode" },
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(afftdn);
+
+static int get_band_noise(AudioFFTDeNoiseContext *s,
+                          int band, double a,
+                          double b, double c)
+{
+    double d1, d2, d3;
+
+    d1 = a / s->band_centre[band];
+    d1 = 10.0 * log(1.0 + d1 * d1) / M_LN10;
+    d2 = b / s->band_centre[band];
+    d2 = 10.0 * log(1.0 + d2 * d2) / M_LN10;
+    d3 = s->band_centre[band] / c;
+    d3 = 10.0 * log(1.0 + d3 * d3) / M_LN10;
+
+    return lrint(-d1 + d2 - d3);
+}
+
+static void factor(double *array, int size)
+{
+    for (int i = 0; i < size - 1; i++) {
+        for (int j = i + 1; j < size; j++) {
+            double d = array[j + i * size] / array[i + i * size];
+
+            array[j + i * size] = d;
+            for (int k = i + 1; k < size; k++) {
+                array[j + k * size] -= d * array[i + k * size];
+            }
+        }
+    }
+}
+
+static void solve(double *matrix, double *vector, int size)
+{
+    for (int i = 0; i < size - 1; i++) {
+        for (int j = i + 1; j < size; j++) {
+            double d = matrix[j + i * size];
+            vector[j] -= d * vector[i];
+        }
+    }
+
+    vector[size - 1] /= matrix[size * size - 1];
+
+    for (int i = size - 2; i >= 0; i--) {
+        double d = vector[i];
+        for (int j = i + 1; j < size; j++)
+            d -= matrix[i + j * size] * vector[j];
+        vector[i] = d / matrix[i + i * size];
+    }
+}
+
+static int process_get_band_noise(AudioFFTDeNoiseContext *s,
+                                  DeNoiseChannel *dnch,
+                                  int band)
+{
+    double product, sum, f;
+    int i = 0;
+
+    if (band < 15)
+        return dnch->band_noise[band];
+
+    for (int j = 0; j < 5; j++) {
+        sum = 0.0;
+        for (int k = 0; k < 15; k++)
+            sum += s->matrix_b[i++] * dnch->band_noise[k];
+        s->vector_b[j] = sum;
+    }
+
+    solve(s->matrix_a, s->vector_b, 5);
+    f = (0.5 * s->sample_rate) / s->band_centre[14];
+    f = 15.0 + log(f / 1.5) / log(1.5);
+    sum = 0.0;
+    product = 1.0;
+    for (int j = 0; j < 5; j++) {
+        sum += product * s->vector_b[j];
+        product *= f;
+    }
+
+    return lrint(sum);
+}
+
+static void calculate_sfm(AudioFFTDeNoiseContext *s,
+                          DeNoiseChannel *dnch,
+                          int start, int end)
+{
+    double d1 = 0.0, d2 = 1.0;
+    int i = 0, j = 0;
+
+    for (int k = start; k < end; k++) {
+        if (dnch->noisy_data[k] > s->sample_floor) {
+            j++;
+            d1 += dnch->noisy_data[k];
+            d2 *= dnch->noisy_data[k];
+            if (d2 > 1.0E100) {
+                d2 *= 1.0E-100;
+                i++;
+            } else if (d2 < 1.0E-100) {
+                d2 *= 1.0E100;
+                i--;
+            }
+        }
+    }
+    if (j > 1) {
+        d1 /= j;
+        dnch->sfm_results[0] = d1;
+        d2 = log(d2) + 230.2585 * i;
+        d2 /= j;
+        d1 = log(d1);
+        dnch->sfm_results[1] = d1;
+        dnch->sfm_results[2] = d1 - d2;
+    } else {
+        dnch->sfm_results[0] = s->auto_floor;
+        dnch->sfm_results[1] = dnch->sfm_threshold;
+        dnch->sfm_results[2] = dnch->sfm_threshold;
+    }
+}
+
+static double limit_gain(double a, double b)
+{
+    if (a > 1.0)
+        return (b * a - 1.0) / (b + a - 2.0);
+    if (a < 1.0)
+        return (b * a - 2.0 * a + 1.0) / (b - a);
+    return 1.0;
+}
+
+static void process_frame(AudioFFTDeNoiseContext *s, DeNoiseChannel *dnch,
+                          FFTComplex *fft_data,
+                          double *prior, double *prior_band_excit, int track_noise)
+{
+    double d1, d2, d3, gain;
+    int n, i1;
+
+    d1 = fft_data[0].re * fft_data[0].re;
+    dnch->noisy_data[0] = d1;
+    d2 = d1 / dnch->abs_var[0];
+    d3 = RATIO * prior[0] + RRATIO * fmax(d2 - 1.0, 0.0);
+    gain = d3 / (1.0 + d3);
+    gain *= (gain + M_PI_4 / fmax(d2, 1.0E-6));
+    prior[0] = (d2 * gain);
+    dnch->clean_data[0] = (d1 * gain);
+    gain = sqrt(gain);
+    dnch->gain[0] = gain;
+    n = 0;
+    for (int i = 1; i < s->fft_length2; i++) {
+        d1 = fft_data[i].re * fft_data[i].re + fft_data[i].im * fft_data[i].im;
+        if (d1 > s->sample_floor)
+            n = i;
+
+        dnch->noisy_data[i] = d1;
+        d2 = d1 / dnch->abs_var[i];
+        d3 = RATIO * prior[i] + RRATIO * fmax(d2 - 1.0, 0.0);
+        gain = d3 / (1.0 + d3);
+        gain *= (gain + M_PI_4 / fmax(d2, 1.0E-6));
+        prior[i] = d2 * gain;
+        dnch->clean_data[i] = d1 * gain;
+        gain = sqrt(gain);
+        dnch->gain[i] = gain;
+    }
+    d1 = fft_data[0].im * fft_data[0].im;
+    if (d1 > s->sample_floor)
+        n = s->fft_length2;
+
+    dnch->noisy_data[s->fft_length2] = d1;
+    d2 = d1 / dnch->abs_var[s->fft_length2];
+    d3 = RATIO * prior[s->fft_length2] + RRATIO * fmax(d2 - 1.0, 0.0);
+    gain = d3 / (1.0 + d3);
+    gain *= gain + M_PI_4 / fmax(d2, 1.0E-6);
+    prior[s->fft_length2] = d2 * gain;
+    dnch->clean_data[s->fft_length2] = d1 * gain;
+    gain = sqrt(gain);
+    dnch->gain[s->fft_length2] = gain;
+    if (n > s->fft_length2 - 2) {
+        n = s->bin_count;
+        i1 = s->noise_band_count;
+    } else {
+        i1 = 0;
+        for (int i = 0; i <= s->noise_band_count; i++) {
+            if (n > 1.1 * s->noise_band_edge[i]) {
+                i1 = i;
+            }
+        }
+    }
+
+    if (track_noise && (i1 > s->noise_band_count / 2)) {
+        int j = FFMIN(n, s->noise_band_edge[i1]);
+        int m = 3, k;
+
+        for (k = i1 - 1; k >= 0; k--) {
+            int i = s->noise_band_edge[k];
+            calculate_sfm(s, dnch, i, j);
+            dnch->noise_band_sample[k] = dnch->sfm_results[0];
+            if (dnch->sfm_results[2] + 0.013 * m * fmax(0.0, dnch->sfm_results[1] - 20.53) >= dnch->sfm_threshold) {
+                break;
+            }
+            j = i;
+            m++;
+        }
+
+        if (k < i1 - 1) {
+            double sum = 0.0, min, max;
+            int i;
+
+            for (i = i1 - 1; i > k; i--) {
+                min = log(dnch->noise_band_sample[i] / dnch->noise_band_auto_var[i]);
+                sum += min;
+            }
+
+            i = i1 - k - 1;
+            if (i < 5) {
+                min = 3.0E-4 * i * i;
+            } else {
+                min = 3.0E-4 * (8 * i - 16);
+            }
+            if (i < 3) {
+                max = 2.0E-4 * i * i;
+            } else {
+                max = 2.0E-4 * (4 * i - 4);
+            }
+
+            if (s->track_residual) {
+                if (s->last_noise_floor > s->last_residual_floor + 9) {
+                    min *= 0.5;
+                    max *= 0.75;
+                } else if (s->last_noise_floor > s->last_residual_floor + 6) {
+                    min *= 0.4;
+                    max *= 1.0;
+                } else if (s->last_noise_floor > s->last_residual_floor + 4) {
+                    min *= 0.3;
+                    max *= 1.3;
+                } else if (s->last_noise_floor > s->last_residual_floor + 2) {
+                    min *= 0.2;
+                    max *= 1.6;
+                } else if (s->last_noise_floor > s->last_residual_floor) {
+                    min *= 0.1;
+                    max *= 2.0;
+                } else {
+                    min = 0.0;
+                    max *= 2.5;
+                }
+            }
+
+            sum = av_clipd(sum, -min, max);
+            sum = exp(sum);
+            for (int i = 0; i < 15; i++)
+                dnch->noise_band_auto_var[i] *= sum;
+        } else if (dnch->sfm_results[2] >= dnch->sfm_threshold) {
+            dnch->sfm_fail_flags[s->block_count & 0x1FF] = 1;
+            dnch->sfm_fail_total += 1;
+        }
+    }
+
+    for (int i = 0; i < s->number_of_bands; i++) {
+        dnch->band_excit[i] = 0.0;
+        dnch->band_amt[i] = 0.0;
+    }
+
+    for (int i = 0; i < s->bin_count; i++) {
+        dnch->band_excit[s->bin2band[i]] += dnch->clean_data[i];
+    }
+
+    for (int i = 0; i < s->number_of_bands; i++) {
+        dnch->band_excit[i] = fmax(dnch->band_excit[i],
+                                s->band_alpha[i] * dnch->band_excit[i] +
+                                s->band_beta[i] * prior_band_excit[i]);
+        prior_band_excit[i] = dnch->band_excit[i];
+    }
+
+    for (int j = 0, i = 0; j < s->number_of_bands; j++) {
+        for (int k = 0; k < s->number_of_bands; k++) {
+            dnch->band_amt[j] += dnch->spread_function[i++] * dnch->band_excit[k];
+        }
+    }
+
+    for (int i = 0; i < s->bin_count; i++)
+        dnch->amt[i] = dnch->band_amt[s->bin2band[i]];
+
+    if (dnch->amt[0] > dnch->abs_var[0]) {
+        dnch->gain[0] = 1.0;
+    } else if (dnch->amt[0] > dnch->min_abs_var[0]) {
+        double limit = sqrt(dnch->abs_var[0] / dnch->amt[0]);
+        dnch->gain[0] = limit_gain(dnch->gain[0], limit);
+    } else {
+        dnch->gain[0] = limit_gain(dnch->gain[0], s->max_gain);
+    }
+    if (dnch->amt[s->fft_length2] > dnch->abs_var[s->fft_length2]) {
+        dnch->gain[s->fft_length2] = 1.0;
+    } else if (dnch->amt[s->fft_length2] > dnch->min_abs_var[s->fft_length2]) {
+        double limit = sqrt(dnch->abs_var[s->fft_length2] / dnch->amt[s->fft_length2]);
+        dnch->gain[s->fft_length2] = limit_gain(dnch->gain[s->fft_length2], limit);
+    } else {
+        dnch->gain[s->fft_length2] = limit_gain(dnch->gain[s->fft_length2], s->max_gain);
+    }
+
+    for (int i = 1; i < s->fft_length2; i++) {
+        if (dnch->amt[i] > dnch->abs_var[i]) {
+            dnch->gain[i] = 1.0;
+        } else if (dnch->amt[i] > dnch->min_abs_var[i]) {
+            double limit = sqrt(dnch->abs_var[i] / dnch->amt[i]);
+            dnch->gain[i] = limit_gain(dnch->gain[i], limit);
+        } else {
+            dnch->gain[i] = limit_gain(dnch->gain[i], s->max_gain);
+        }
+    }
+
+    gain = dnch->gain[0];
+    dnch->clean_data[0] = (gain * gain * dnch->noisy_data[0]);
+    fft_data[0].re *= gain;
+    gain = dnch->gain[s->fft_length2];
+    dnch->clean_data[s->fft_length2] = (gain * gain * dnch->noisy_data[s->fft_length2]);
+    fft_data[0].im *= gain;
+    for (int i = 1; i < s->fft_length2; i++) {
+        gain = dnch->gain[i];
+        dnch->clean_data[i] = (gain * gain * dnch->noisy_data[i]);
+        fft_data[i].re *= gain;
+        fft_data[i].im *= gain;
+    }
+}
+
+static double freq2bark(double x)
+{
+    double d = x / 7500.0;
+
+    return 13.0 * atan(7.6E-4 * x) + 3.5 * atan(d * d);
+}
+
+static int get_band_centre(AudioFFTDeNoiseContext *s, int band)
+{
+    if (band == -1)
+        return lrint(s->band_centre[0] / 1.5);
+
+    return s->band_centre[band];
+}
+
+static int get_band_edge(AudioFFTDeNoiseContext *s, int band)
+{
+    int i;
+
+    if (band == 15) {
+        i = lrint(s->band_centre[14] * 1.224745);
+    } else {
+        i = lrint(s->band_centre[band] / 1.224745);
+    }
+
+    return FFMIN(i, s->sample_rate / 2);
+}
+
+static void set_band_parameters(AudioFFTDeNoiseContext *s,
+                                DeNoiseChannel *dnch)
+{
+    double band_noise, d2, d3, d4, d5;
+    int i = 0, j = 0, k = 0;
+
+    d5 = 0.0;
+    band_noise = process_get_band_noise(s, dnch, 0);
+    for (int m = j; m <= s->fft_length2; m++) {
+        if (m == j) {
+            i = j;
+            d5 = band_noise;
+            if (k == 15) {
+                j = s->bin_count;
+            } else {
+                j = s->fft_length * get_band_centre(s, k) / s->sample_rate;
+            }
+            d2 = j - i;
+            band_noise = process_get_band_noise(s, dnch, k);
+            k++;
+        }
+        d3 = (j - m) / d2;
+        d4 = (m - i) / d2;
+        dnch->rel_var[m] = exp((d5 * d3 + band_noise * d4) * C);
+    }
+    dnch->rel_var[s->fft_length2] = exp(band_noise * C);
+
+    for (i = 0; i < 15; i++)
+        dnch->noise_band_auto_var[i] = s->max_var * exp((process_get_band_noise(s, dnch, i) - 2.0) * C);
+
+    for (i = 0; i <= s->fft_length2; i++) {
+        dnch->abs_var[i] = fmax(s->max_var * dnch->rel_var[i], 1.0);
+        dnch->min_abs_var[i] = s->gain_scale * dnch->abs_var[i];
+    }
+}
+
+static void read_custom_noise(AudioFFTDeNoiseContext *s, int ch)
+{
+    DeNoiseChannel *dnch = &s->dnch[ch];
+    char *p, *arg, *saveptr = NULL;
+    int i, ret, band_noise[15] = { 0 };
+
+    if (!s->band_noise_str)
+        return;
+
+    p = av_strdup(s->band_noise_str);
+    if (!p)
+        return;
+
+    for (i = 0; i < 15; i++) {
+        if (!(arg = av_strtok(p, "| ", &saveptr)))
+            break;
+
+        p = NULL;
+
+        ret = sscanf(arg, "%d", &band_noise[i]);
+        if (ret != 1) {
+            av_log(s, AV_LOG_ERROR, "Custom band noise must be integer.\n");
+            break;
+        }
+
+        band_noise[i] = av_clip(band_noise[i], -24, 24);
+    }
+
+    av_free(p);
+    memcpy(dnch->band_noise, band_noise, sizeof(band_noise));
+}
+
+static void set_parameters(AudioFFTDeNoiseContext *s)
+{
+    if (s->last_noise_floor != s->noise_floor)
+        s->last_noise_floor = s->noise_floor;
+
+    if (s->track_residual)
+        s->last_noise_floor = fmaxf(s->last_noise_floor, s->residual_floor);
+
+    s->max_var = s->floor * exp((100.0 + s->last_noise_floor) * C);
+
+    if (s->track_residual) {
+        s->last_residual_floor = s->residual_floor;
+        s->last_noise_reduction = fmax(s->last_noise_floor - s->last_residual_floor, 0);
+        s->max_gain = exp(s->last_noise_reduction * (0.5 * C));
+    } else if (s->noise_reduction != s->last_noise_reduction) {
+        s->last_noise_reduction = s->noise_reduction;
+        s->last_residual_floor = av_clipf(s->last_noise_floor - s->last_noise_reduction, -80, -20);
+        s->max_gain = exp(s->last_noise_reduction * (0.5 * C));
+    }
+
+    s->gain_scale = 1.0 / (s->max_gain * s->max_gain);
+
+    for (int ch = 0; ch < s->channels; ch++) {
+        DeNoiseChannel *dnch = &s->dnch[ch];
+
+        set_band_parameters(s, dnch);
+    }
+}
+
+static int config_input(AVFilterLink *inlink)
+{
+    AVFilterContext *ctx = inlink->dst;
+    AudioFFTDeNoiseContext *s = ctx->priv;
+    double wscale, sar, sum, sdiv;
+    int i, j, k, m, n;
+
+    s->dnch = av_calloc(inlink->channels, sizeof(*s->dnch));
+    if (!s->dnch)
+        return AVERROR(ENOMEM);
+
+    s->pts = AV_NOPTS_VALUE;
+    s->channels = inlink->channels;
+    s->sample_rate = inlink->sample_rate;
+    s->sample_advance = s->sample_rate / 80;
+    s->window_length = 3 * s->sample_advance;
+    s->fft_length2 = 1 << (32 - ff_clz(s->window_length));
+    s->fft_length = s->fft_length2 * 2;
+    s->buffer_length = s->fft_length * 2;
+    s->bin_count = s->fft_length2 + 1;
+
+    s->band_centre[0] = 80;
+    for (i = 1; i < 15; i++) {
+        s->band_centre[i] = lrint(1.5 * s->band_centre[i - 1] + 5.0);
+        if (s->band_centre[i] < 1000) {
+            s->band_centre[i] = 10 * (s->band_centre[i] / 10);
+        } else if (s->band_centre[i] < 5000) {
+            s->band_centre[i] = 50 * ((s->band_centre[i] + 20) / 50);
+        } else if (s->band_centre[i] < 15000) {
+            s->band_centre[i] = 100 * ((s->band_centre[i] + 45) / 100);
+        } else {
+            s->band_centre[i] = 1000 * ((s->band_centre[i] + 495) / 1000);
+        }
+    }
+
+    for (j = 0; j < 5; j++) {
+        for (k = 0; k < 5; k++) {
+            s->matrix_a[j + k * 5] = 0.0;
+            for (m = 0; m < 15; m++)
+                s->matrix_a[j + k * 5] += pow(m, j + k);
+        }
+    }
+
+    factor(s->matrix_a, 5);
+
+    i = 0;
+    for (j = 0; j < 5; j++)
+        for (k = 0; k < 15; k++)
+            s->matrix_b[i++] = pow(k, j);
+
+    i = 0;
+    for (j = 0; j < 15; j++)
+        for (k = 0; k < 5; k++)
+            s->matrix_c[i++] = pow(j, k);
+
+    s->window = av_calloc(s->window_length, sizeof(*s->window));
+    s->bin2band = av_calloc(s->bin_count, sizeof(*s->bin2band));
+    if (!s->window || !s->bin2band)
+        return AVERROR(ENOMEM);
+
+    sdiv = s->sample_rate / 17640.0;
+    for (i = 0; i <= s->fft_length2; i++)
+        s->bin2band[i] = lrint(sdiv * freq2bark((0.5 * i * s->sample_rate) / s->fft_length2));
+
+    s->number_of_bands = s->bin2band[s->fft_length2] + 1;
+
+    s->band_alpha = av_calloc(s->number_of_bands, sizeof(*s->band_alpha));
+    s->band_beta = av_calloc(s->number_of_bands, sizeof(*s->band_beta));
+    if (!s->band_alpha || !s->band_beta)
+        return AVERROR(ENOMEM);
+
+    for (int ch = 0; ch < inlink->channels; ch++) {
+        DeNoiseChannel *dnch = &s->dnch[ch];
+
+        switch (s->noise_type) {
+        case WHITE_NOISE:
+            for (i = 0; i < 15; i++)
+                dnch->band_noise[i] = 0;
+            break;
+        case VINYL_NOISE:
+            for (i = 0; i < 15; i++)
+                dnch->band_noise[i] = get_band_noise(s, i, 50.0, 500.5, 2125.0) + FFMAX(i - 7, 0);
+            break;
+        case SHELLAC_NOISE:
+            for (i = 0; i < 15; i++)
+                dnch->band_noise[i] = get_band_noise(s, i, 1.0, 500.0, 1.0E10) + FFMAX(i - 12, -5);
+        case CUSTOM_NOISE:
+            read_custom_noise(s, ch);
+            break;
+        default:
+            return AVERROR_BUG;
+        }
+
+
+        dnch->sfm_threshold = 0.8;
+        dnch->sfm_alpha = 0.05;
+        for (i = 0; i < 512; i++)
+            dnch->sfm_fail_flags[i] = 0;
+
+        dnch->sfm_fail_total = 0;
+        j = FFMAX((int)(10.0 * (1.3 - dnch->sfm_threshold)), 1);
+
+        for (i = 0; i < 512; i += j) {
+            dnch->sfm_fail_flags[i] = 1;
+            dnch->sfm_fail_total += 1;
+        }
+
+        dnch->amt = av_calloc(s->bin_count, sizeof(*dnch->amt));
+        dnch->band_amt = av_calloc(s->number_of_bands, sizeof(*dnch->band_amt));
+        dnch->band_excit = av_calloc(s->number_of_bands, sizeof(*dnch->band_excit));
+        dnch->gain = av_calloc(s->bin_count, sizeof(*dnch->gain));
+        dnch->prior = av_calloc(s->bin_count, sizeof(*dnch->prior));
+        dnch->prior_band_excit = av_calloc(s->number_of_bands, sizeof(*dnch->prior_band_excit));
+        dnch->clean_data = av_calloc(s->bin_count, sizeof(*dnch->clean_data));
+        dnch->noisy_data = av_calloc(s->bin_count, sizeof(*dnch->noisy_data));
+        dnch->out_samples = av_calloc(s->buffer_length, sizeof(*dnch->out_samples));
+        dnch->abs_var = av_calloc(s->bin_count, sizeof(*dnch->abs_var));
+        dnch->rel_var = av_calloc(s->bin_count, sizeof(*dnch->rel_var));
+        dnch->min_abs_var = av_calloc(s->bin_count, sizeof(*dnch->min_abs_var));
+        dnch->fft_data = av_calloc(s->fft_length2 + 1, sizeof(*dnch->fft_data));
+        dnch->fft  = av_fft_init(av_log2(s->fft_length2), 0);
+        dnch->ifft = av_fft_init(av_log2(s->fft_length2), 1);
+        dnch->spread_function = av_calloc(s->number_of_bands * s->number_of_bands,
+                                          sizeof(*dnch->spread_function));
+
+        if (!dnch->amt ||
+            !dnch->band_amt ||
+            !dnch->band_excit ||
+            !dnch->gain ||
+            !dnch->prior ||
+            !dnch->prior_band_excit ||
+            !dnch->clean_data ||
+            !dnch->noisy_data ||
+            !dnch->out_samples ||
+            !dnch->fft_data ||
+            !dnch->abs_var ||
+            !dnch->rel_var ||
+            !dnch->min_abs_var ||
+            !dnch->spread_function ||
+            !dnch->fft ||
+            !dnch->ifft)
+            return AVERROR(ENOMEM);
+    }
+
+    for (int ch = 0; ch < inlink->channels; ch++) {
+        DeNoiseChannel *dnch = &s->dnch[ch];
+        double *prior_band_excit = dnch->prior_band_excit;
+        double *prior = dnch->prior;
+        double min, max;
+        double p1, p2;
+
+        p1 = pow(0.1, 2.5 / sdiv);
+        p2 = pow(0.1, 1.0 / sdiv);
+        j = 0;
+        for (m = 0; m < s->number_of_bands; m++) {
+            for (n = 0; n < s->number_of_bands; n++) {
+                if (n < m) {
+                    dnch->spread_function[j++] = pow(p2, m - n);
+                } else if (n > m) {
+                    dnch->spread_function[j++] = pow(p1, n - m);
+                } else {
+                    dnch->spread_function[j++] = 1.0;
+                }
+            }
+        }
+
+        for (m = 0; m < s->number_of_bands; m++) {
+            dnch->band_excit[m] = 0.0;
+            prior_band_excit[m] = 0.0;
+        }
+
+        for (m = 0; m <= s->fft_length2; m++)
+            dnch->band_excit[s->bin2band[m]] += 1.0;
+
+        j = 0;
+        for (m = 0; m < s->number_of_bands; m++) {
+            for (n = 0; n < s->number_of_bands; n++)
+                prior_band_excit[m] += dnch->spread_function[j++] * dnch->band_excit[n];
+        }
+
+        min = pow(0.1, 2.5);
+        max = pow(0.1, 1.0);
+        for (int i = 0; i < s->number_of_bands; i++) {
+            if (i < lrint(12.0 * sdiv)) {
+                dnch->band_excit[i] = pow(0.1, 1.45 + 0.1 * i / sdiv);
+            } else {
+                dnch->band_excit[i] = pow(0.1, 2.5 - 0.2 * (i / sdiv - 14.0));
+            }
+            dnch->band_excit[i] = av_clipd(dnch->band_excit[i], min, max);
+        }
+
+        for (int i = 0; i <= s->fft_length2; i++)
+            prior[i] = RRATIO;
+        for (int i = 0; i < s->buffer_length; i++)
+            dnch->out_samples[i] = 0;
+
+        j = 0;
+        for (int i = 0; i < s->number_of_bands; i++)
+            for (int k = 0; k < s->number_of_bands; k++)
+                dnch->spread_function[j++] *= dnch->band_excit[i] / prior_band_excit[i];
+    }
+
+    j = 0;
+    sar = s->sample_advance / s->sample_rate;
+    for (int i = 0; i <= s->fft_length2; i++) {
+        if ((i == s->fft_length2) || (s->bin2band[i] > j)) {
+            double d6 = (i - 1) * s->sample_rate / s->fft_length;
+            double d7 = fmin(0.008 + 2.2 / d6, 0.03);
+            s->band_alpha[j] = exp(-sar / d7);
+            s->band_beta[j] = 1.0 - s->band_alpha[j];
+            j = s->bin2band[i];
+        }
+    }
+
+    wscale = sqrt(16.0 / (9.0 * s->fft_length));
+    sum = 0.0;
+    for (int i = 0; i < s->window_length; i++) {
+        double d10 = sin(i * M_PI / s->window_length);
+        d10 *= wscale * d10;
+        s->window[i] = d10;
+        sum += d10 * d10;
+    }
+
+    s->window_weight = 0.5 * sum;
+    s->floor = (1LL << 48) * exp(-23.025558369790467) * s->window_weight;
+    s->sample_floor = s->floor * exp(4.144600506562284);
+    s->auto_floor = s->floor * exp(6.907667510937141);
+
+    set_parameters(s);
+
+    s->noise_band_edge[0] = FFMIN(s->fft_length2, s->fft_length * get_band_edge(s, 0) / s->sample_rate);
+    i = 0;
+    for (int j = 1; j < 16; j++) {
+        s->noise_band_edge[j] = FFMIN(s->fft_length2, s->fft_length * get_band_edge(s, j) / s->sample_rate);
+        if (s->noise_band_edge[j] > lrint(1.1 * s->noise_band_edge[j - 1]))
+            i++;
+        s->noise_band_edge[16] = i;
+    }
+    s->noise_band_count = s->noise_band_edge[16];
+
+    s->fifo = av_audio_fifo_alloc(inlink->format, inlink->channels, s->fft_length);
+    if (!s->fifo)
+        return AVERROR(ENOMEM);
+
+    return 0;
+}
+
+static void preprocess(FFTComplex *in, int len)
+{
+    double d1, d2, d3, d4, d5, d6, d7, d8, d9, d10;
+    int n, i, k;
+
+    d5 = 2.0 * M_PI / len;
+    d8 = sin(0.5 * d5);
+    d8 = -2.0 * d8 * d8;
+    d7 = sin(d5);
+    d9 = 1.0 + d8;
+    d6 = d7;
+    n = len / 2;
+
+    for (i = 1; i < len / 4; i++) {
+        k = n - i;
+        d2 = 0.5 * (in[i].re + in[k].re);
+        d1 = 0.5 * (in[i].im - in[k].im);
+        d4 = 0.5 * (in[i].im + in[k].im);
+        d3 = 0.5 * (in[k].re - in[i].re);
+        in[i].re = d2 + d9 * d4 + d6 * d3;
+        in[i].im = d1 + d9 * d3 - d6 * d4;
+        in[k].re = d2 - d9 * d4 - d6 * d3;
+        in[k].im = -d1 + d9 * d3 - d6 * d4;
+        d10 = d9;
+        d9 += d9 * d8 - d6 * d7;
+        d6 += d6 * d8 + d10 * d7;
+    }
+
+    d2 = in[0].re;
+    in[0].re = d2 + in[0].im;
+    in[0].im = d2 - in[0].im;
+}
+
+static void postprocess(FFTComplex *in, int len)
+{
+    double d1, d2, d3, d4, d5, d6, d7, d8, d9, d10;
+    int n, i, k;
+
+    d5 = 2.0 * M_PI / len;
+    d8 = sin(0.5 * d5);
+    d8 = -2.0 * d8 * d8;
+    d7 = sin(d5);
+    d9 = 1.0 + d8;
+    d6 = d7;
+    n = len / 2;
+    for (i = 1; i < len / 4; i++) {
+        k = n - i;
+        d2 = 0.5 * (in[i].re + in[k].re);
+        d1 = 0.5 * (in[i].im - in[k].im);
+        d4 = 0.5 * (in[i].re - in[k].re);
+        d3 = 0.5 * (in[i].im + in[k].im);
+        in[i].re = d2 - d9 * d3 - d6 * d4;
+        in[i].im = d1 + d9 * d4 - d6 * d3;
+        in[k].re = d2 + d9 * d3 + d6 * d4;
+        in[k].im = -d1 + d9 * d4 - d6 * d3;
+        d10 = d9;
+        d9 += d9 * d8 - d6 * d7;
+        d6 += d6 * d8 + d10 * d7;
+    }
+    d2 = in[0].re;
+    in[0].re = 0.5 * (d2 + in[0].im);
+    in[0].im = 0.5 * (d2 - in[0].im);
+}
+
+static void init_sample_noise(DeNoiseChannel *dnch)
+{
+    for (int i = 0; i < 15; i++) {
+        dnch->noise_band_norm[i] = 0.0;
+        dnch->noise_band_avr[i] = 0.0;
+        dnch->noise_band_avi[i] = 0.0;
+        dnch->noise_band_var[i] = 0.0;
+    }
+}
+
+static void sample_noise_block(AudioFFTDeNoiseContext *s,
+                               DeNoiseChannel *dnch,
+                               AVFrame *in, int ch)
+{
+    float *src = (float *)in->extended_data[ch];
+    double mag2, var = 0.0, avr = 0.0, avi = 0.0;
+    int edge, j, k, n, edgemax;
+
+    for (int i = 0; i < s->window_length; i++) {
+        dnch->fft_data[i].re = s->window[i] * src[i] * (1LL << 24);
+        dnch->fft_data[i].im = 0.0;
+    }
+
+    for (int i = s->window_length; i < s->fft_length2; i++) {
+        dnch->fft_data[i].re = 0.0;
+        dnch->fft_data[i].im = 0.0;
+    }
+
+    av_fft_permute(dnch->fft, dnch->fft_data);
+    av_fft_calc(dnch->fft, dnch->fft_data);
+
+    preprocess(dnch->fft_data, s->fft_length);
+
+    edge = s->noise_band_edge[0];
+    j = edge;
+    k = 0;
+    n = j;
+    edgemax = fmin(s->fft_length2, s->noise_band_edge[15]);
+    dnch->fft_data[s->fft_length2].re = dnch->fft_data[0].im;
+    dnch->fft_data[0].im = 0.0;
+    dnch->fft_data[s->fft_length2].im = 0.0;
+
+    for (int i = j; i <= edgemax; i++) {
+        if ((i == j) && (i < edgemax)) {
+            if (j > edge) {
+                dnch->noise_band_norm[k - 1] += j - edge;
+                dnch->noise_band_avr[k - 1] += avr;
+                dnch->noise_band_avi[k - 1] += avi;
+                dnch->noise_band_var[k - 1] += var;
+            }
+            k++;
+            edge = j;
+            j = s->noise_band_edge[k];
+            if (k == 15) {
+                j++;
+            }
+            var = 0.0;
+            avr = 0.0;
+            avi = 0.0;
+        }
+        avr += dnch->fft_data[n].re;
+        avi += dnch->fft_data[n].im;
+        mag2 = dnch->fft_data[n].re * dnch->fft_data[n].re +
+               dnch->fft_data[n].im * dnch->fft_data[n].im;
+
+        mag2 = fmax(mag2, s->sample_floor);
+
+        dnch->noisy_data[i] = mag2;
+        var += mag2;
+        n++;
+    }
+
+    dnch->noise_band_norm[k - 1] += j - edge;
+    dnch->noise_band_avr[k - 1] += avr;
+    dnch->noise_band_avi[k - 1] += avi;
+    dnch->noise_band_var[k - 1] += var;
+}
+
+static void finish_sample_noise(AudioFFTDeNoiseContext *s,
+                                DeNoiseChannel *dnch,
+                                double *sample_noise)
+{
+    for (int i = 0; i < s->noise_band_count; i++) {
+        dnch->noise_band_avr[i] /= dnch->noise_band_norm[i];
+        dnch->noise_band_avi[i] /= dnch->noise_band_norm[i];
+        dnch->noise_band_var[i] /= dnch->noise_band_norm[i];
+        dnch->noise_band_var[i] -= dnch->noise_band_avr[i] * dnch->noise_band_avr[i] +
+                                   dnch->noise_band_avi[i] * dnch->noise_band_avi[i];
+        dnch->noise_band_auto_var[i] = dnch->noise_band_var[i];
+        sample_noise[i] = (1.0 / C) * log(dnch->noise_band_var[i] / s->floor) - 100.0;
+    }
+    if (s->noise_band_count < 15) {
+        for (int i = s->noise_band_count; i < 15; i++)
+            sample_noise[i] = sample_noise[i - 1];
+    }
+}
+
+static void set_noise_profile(AudioFFTDeNoiseContext *s,
+                              DeNoiseChannel *dnch,
+                              double *sample_noise,
+                              int new_profile)
+{
+    int new_band_noise[15];
+    double temp[15];
+    double sum = 0.0, d1;
+    float new_noise_floor;
+    int i, n;
+
+    for (int m = 0; m < 15; m++)
+        temp[m] = sample_noise[m];
+
+    if (new_profile) {
+        i = 0;
+        for (int m = 0; m < 5; m++) {
+            sum = 0.0;
+            for (n = 0; n < 15; n++)
+                sum += s->matrix_b[i++] * temp[n];
+            s->vector_b[m] = sum;
+        }
+        solve(s->matrix_a, s->vector_b, 5);
+        i = 0;
+        for (int m = 0; m < 15; m++) {
+            sum = 0.0;
+            for (n = 0; n < 5; n++)
+                sum += s->matrix_c[i++] * s->vector_b[n];
+            temp[m] = sum;
+        }
+    }
+
+    sum = 0.0;
+    for (int m = 0; m < 15; m++)
+        sum += temp[m];
+
+    d1 = (int)(sum / 15.0 - 0.5);
+    if (!new_profile)
+        i = lrint(temp[7] - d1);
+
+    for (d1 -= dnch->band_noise[7] - i; d1 > -20.0; d1 -= 1.0)
+        ;
+
+    for (int m = 0; m < 15; m++)
+        temp[m] -= d1;
+
+    new_noise_floor = d1 + 2.5;
+
+    if (new_profile) {
+        av_log(s, AV_LOG_INFO, "bn=");
+        for (int m = 0; m < 15; m++) {
+            new_band_noise[m] = lrint(temp[m]);
+            new_band_noise[m] = av_clip(new_band_noise[m], -24, 24);
+            av_log(s, AV_LOG_INFO, "%d ", new_band_noise[m]);
+        }
+        av_log(s, AV_LOG_INFO, "\n");
+        memcpy(dnch->band_noise, new_band_noise, sizeof(new_band_noise));
+    }
+
+    if (s->track_noise)
+        s->noise_floor = new_noise_floor;
+}
+
+typedef struct ThreadData {
+    AVFrame *in;
+} ThreadData;
+
+static int filter_channel(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
+{
+    AudioFFTDeNoiseContext *s = ctx->priv;
+    ThreadData *td = arg;
+    AVFrame *in = td->in;
+    const int start = (in->channels * jobnr) / nb_jobs;
+    const int end = (in->channels * (jobnr+1)) / nb_jobs;
+
+    for (int ch = start; ch < end; ch++) {
+        DeNoiseChannel *dnch = &s->dnch[ch];
+        const float *src = (const float *)in->extended_data[ch];
+        double *dst = dnch->out_samples;
+
+        if (s->track_noise) {
+            int i = s->block_count & 0x1FF;
+
+            if (dnch->sfm_fail_flags[i])
+                dnch->sfm_fail_total--;
+            dnch->sfm_fail_flags[i] = 0;
+            dnch->sfm_threshold *= 1.0 - dnch->sfm_alpha;
+            dnch->sfm_threshold += dnch->sfm_alpha * (0.5 + (1.0 / 640) * dnch->sfm_fail_total);
+        }
+
+        for (int m = 0; m < s->window_length; m++) {
+            dnch->fft_data[m].re = s->window[m] * src[m] * (1LL << 24);
+            dnch->fft_data[m].im = 0;
+        }
+
+        for (int m = s->window_length; m < s->fft_length2; m++) {
+            dnch->fft_data[m].re = 0;
+            dnch->fft_data[m].im = 0;
+        }
+
+        av_fft_permute(dnch->fft, dnch->fft_data);
+        av_fft_calc(dnch->fft, dnch->fft_data);
+
+        preprocess(dnch->fft_data, s->fft_length);
+        process_frame(s, dnch, dnch->fft_data,
+                      dnch->prior,
+                      dnch->prior_band_excit,
+                      s->track_noise);
+        postprocess(dnch->fft_data, s->fft_length);
+
+        av_fft_permute(dnch->ifft, dnch->fft_data);
+        av_fft_calc(dnch->ifft, dnch->fft_data);
+
+        for (int m = 0; m < s->window_length; m++)
+            dst[m] += s->window[m] * dnch->fft_data[m].re / (1LL << 24);
+    }
+
+    return 0;
+}
+
+static void get_auto_noise_levels(AudioFFTDeNoiseContext *s,
+                                  DeNoiseChannel *dnch,
+                                  double *levels)
+{
+    if (s->noise_band_count > 0) {
+        for (int i = 0; i < s->noise_band_count; i++) {
+            levels[i] = (1.0 / C) * log(dnch->noise_band_auto_var[i] / s->floor) - 100.0;
+        }
+        if (s->noise_band_count < 15) {
+            for (int i = s->noise_band_count; i < 15; i++)
+                levels[i] = levels[i - 1];
+        }
+    } else {
+        for (int i = 0; i < 15; i++) {
+            levels[i] = -100.0;
+        }
+    }
+}
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
+{
+    AVFilterContext *ctx = inlink->dst;
+    AVFilterLink *outlink = ctx->outputs[0];
+    AudioFFTDeNoiseContext *s = ctx->priv;
+    AVFrame *out = NULL, *in = NULL;
+    ThreadData td;
+    int ret = 0;
+
+    if (s->pts == AV_NOPTS_VALUE)
+        s->pts = frame->pts;
+
+    ret = av_audio_fifo_write(s->fifo, (void **)frame->extended_data, frame->nb_samples);
+    av_frame_free(&frame);
+    if (ret < 0)
+        return ret;
+
+    while (av_audio_fifo_size(s->fifo) >= s->window_length) {
+        if (!in) {
+            in = ff_get_audio_buffer(outlink, s->window_length);
+            if (!in)
+                return AVERROR(ENOMEM);
+        }
+
+        ret = av_audio_fifo_peek(s->fifo, (void **)in->extended_data, s->window_length);
+        if (ret < 0)
+            break;
+
+        if (s->track_noise) {
+            for (int ch = 0; ch < inlink->channels; ch++) {
+                DeNoiseChannel *dnch = &s->dnch[ch];
+                double levels[15];
+
+                get_auto_noise_levels(s, dnch, levels);
+                set_noise_profile(s, dnch, levels, 0);
+            }
+
+            if (s->noise_floor != s->last_noise_floor)
+                set_parameters(s);
+        }
+
+        if (s->sample_noise_start) {
+            for (int ch = 0; ch < inlink->channels; ch++) {
+                DeNoiseChannel *dnch = &s->dnch[ch];
+
+                init_sample_noise(dnch);
+            }
+            s->sample_noise_start = 0;
+            s->sample_noise = 1;
+        }
+
+        if (s->sample_noise) {
+            for (int ch = 0; ch < inlink->channels; ch++) {
+                DeNoiseChannel *dnch = &s->dnch[ch];
+
+                sample_noise_block(s, dnch, in, ch);
+            }
+        }
+
+        if (s->sample_noise_end) {
+            for (int ch = 0; ch < inlink->channels; ch++) {
+                DeNoiseChannel *dnch = &s->dnch[ch];
+                double sample_noise[15];
+
+                finish_sample_noise(s, dnch, sample_noise);
+                set_noise_profile(s, dnch, sample_noise, 1);
+                set_band_parameters(s, dnch);
+            }
+            s->sample_noise = 0;
+            s->sample_noise_end = 0;
+        }
+
+        s->block_count++;
+        td.in = in;
+        ctx->internal->execute(ctx, filter_channel, &td, NULL,
+                               FFMIN(outlink->channels, ff_filter_get_nb_threads(ctx)));
+
+        out = ff_get_audio_buffer(outlink, s->sample_advance);
+        if (!out) {
+            ret = AVERROR(ENOMEM);
+            break;
+        }
+
+        for (int ch = 0; ch < inlink->channels; ch++) {
+            DeNoiseChannel *dnch = &s->dnch[ch];
+            double *src = dnch->out_samples;
+            float *orig = (float *)in->extended_data[ch];
+            float *dst = (float *)out->extended_data[ch];
+
+            switch (s->output_mode) {
+            case IN_MODE:
+                for (int m = 0; m < s->sample_advance; m++)
+                    dst[m] = orig[m];
+                break;
+            case OUT_MODE:
+                for (int m = 0; m < s->sample_advance; m++)
+                    dst[m] = src[m];
+                break;
+            case NOISE_MODE:
+                for (int m = 0; m < s->sample_advance; m++)
+                    dst[m] = orig[m] - src[m];
+                break;
+            default:
+                return AVERROR_BUG;
+            }
+            memmove(src, src + s->sample_advance, (s->window_length - s->sample_advance) * sizeof(*src));
+            memset(src + (s->window_length - s->sample_advance), 0, s->sample_advance * sizeof(*src));
+        }
+
+        av_audio_fifo_drain(s->fifo, s->sample_advance);
+
+        out->pts = s->pts;
+        ret = ff_filter_frame(outlink, out);
+        if (ret < 0)
+            break;
+        s->pts += s->sample_advance;
+    }
+    av_frame_free(&in);
+
+    return ret;
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    AudioFFTDeNoiseContext *s = ctx->priv;
+
+    av_freep(&s->window);
+    av_freep(&s->bin2band);
+    av_freep(&s->band_alpha);
+    av_freep(&s->band_beta);
+
+    if (s->dnch) {
+        for (int ch = 0; ch < s->channels; ch++) {
+            DeNoiseChannel *dnch = &s->dnch[ch];
+            av_freep(&dnch->amt);
+            av_freep(&dnch->band_amt);
+            av_freep(&dnch->band_excit);
+            av_freep(&dnch->gain);
+            av_freep(&dnch->prior);
+            av_freep(&dnch->prior_band_excit);
+            av_freep(&dnch->clean_data);
+            av_freep(&dnch->noisy_data);
+            av_freep(&dnch->out_samples);
+            av_freep(&dnch->spread_function);
+            av_freep(&dnch->abs_var);
+            av_freep(&dnch->rel_var);
+            av_freep(&dnch->min_abs_var);
+            av_freep(&dnch->fft_data);
+            av_fft_end(dnch->fft);
+            dnch->fft = NULL;
+            av_fft_end(dnch->ifft);
+            dnch->ifft = NULL;
+        }
+        av_freep(&s->dnch);
+    }
+
+    av_audio_fifo_free(s->fifo);
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+    AVFilterFormats *formats = NULL;
+    AVFilterChannelLayouts *layouts = NULL;
+    static const enum AVSampleFormat sample_fmts[] = {
+        AV_SAMPLE_FMT_FLTP,
+        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 int process_command(AVFilterContext *ctx, const char *cmd, const char *args,
+                           char *res, int res_len, int flags)
+{
+    AudioFFTDeNoiseContext *s = ctx->priv;
+    int need_reset = 0;
+
+    if (!strcmp(cmd, "sample_noise") ||
+        !strcmp(cmd, "sn")) {
+        if (!strcmp(args, "start")) {
+            s->sample_noise_start = 1;
+            s->sample_noise_end = 0;
+        } else if (!strcmp(args, "end")) {
+            s->sample_noise_start = 0;
+            s->sample_noise_end = 1;
+        }
+    } else if (!strcmp(cmd, "nr") ||
+               !strcmp(cmd, "noise_reduction")) {
+        float nr;
+
+        if (sscanf(args, "%f", &nr) == 1) {
+            s->noise_reduction = av_clipf(nr, 0.01, 97);
+            need_reset = 1;
+        }
+    } else if (!strcmp(cmd, "nf") ||
+               !strcmp(cmd, "noise_floor")) {
+        float nf;
+
+        if (sscanf(args, "%f", &nf) == 1) {
+            s->noise_floor = av_clipf(nf, -80, -20);
+            need_reset = 1;
+        }
+    } else if (!strcmp(cmd, "output_mode") ||
+               !strcmp(cmd, "om")) {
+        if (!strcmp(args, "i")) {
+            s->output_mode = IN_MODE;
+        } else if (!strcmp(args, "o")) {
+            s->output_mode = OUT_MODE;
+        } else if (!strcmp(args, "n")) {
+            s->output_mode = NOISE_MODE;
+        }
+    }
+
+    if (need_reset)
+        set_parameters(s);
+
+    return 0;
+}
+
+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_afftdn = {
+    .name            = "afftdn",
+    .description     = NULL_IF_CONFIG_SMALL("Denoise audio samples using FFT."),
+    .query_formats   = query_formats,
+    .priv_size       = sizeof(AudioFFTDeNoiseContext),
+    .priv_class      = &afftdn_class,
+    .uninit          = uninit,
+    .inputs          = inputs,
+    .outputs         = outputs,
+    .process_command = process_command,
+    .flags           = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC |
+                       AVFILTER_FLAG_SLICE_THREADS,
+};