libavfilter/af_afftfilt.c - manifest_repos/ffmpeg - Git at Google

 /*
  * Copyright (c) 2016 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/audio_fifo.h"
 #include "libavutil/avstring.h"
 #include "libavfilter/internal.h"
 #include "libavutil/common.h"
 #include "libavutil/opt.h"
 #include "libavcodec/avfft.h"
 #include "libavutil/eval.h"
 #include "audio.h"
 #include "filters.h"
 #include "window_func.h"

 typedef struct AFFTFiltContext {
     const AVClass *class;
     char *real_str;
     char *img_str;
     int fft_size;
     int fft_bits;

     FFTContext *fft, *ifft;
     FFTComplex **fft_data;
     FFTComplex **fft_temp;
     int nb_exprs;
     int channels;
     int window_size;
     AVExpr **real;
     AVExpr **imag;
     AVAudioFifo *fifo;
     int64_t pts;
     int hop_size;
     float overlap;
     AVFrame *buffer;
     int eof;
     int win_func;
     float *window_func_lut;
 } AFFTFiltContext;

 static const char *const var_names[] = {            "sr",     "b",       "nb",        "ch",        "chs",   "pts",     "re",     "im", NULL };
 enum                                   { VAR_SAMPLE_RATE, VAR_BIN, VAR_NBBINS, VAR_CHANNEL, VAR_CHANNELS, VAR_PTS, VAR_REAL, VAR_IMAG, VAR_VARS_NB };

 #define OFFSET(x) offsetof(AFFTFiltContext, x)
 #define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM

 static const AVOption afftfilt_options[] = {
     { "real", "set channels real expressions",       OFFSET(real_str), AV_OPT_TYPE_STRING, {.str = "re" }, 0, 0, A },
     { "imag", "set channels imaginary expressions",  OFFSET(img_str),  AV_OPT_TYPE_STRING, {.str = "im" }, 0, 0, A },
     { "win_size", "set window size", OFFSET(fft_size), AV_OPT_TYPE_INT, {.i64=4096}, 16, 131072, A },
     { "win_func", "set window function", OFFSET(win_func), AV_OPT_TYPE_INT, {.i64 = WFUNC_HANNING}, 0, NB_WFUNC-1, A, "win_func" },
         { "rect",     "Rectangular",      0, AV_OPT_TYPE_CONST, {.i64=WFUNC_RECT},     0, 0, A, "win_func" },
         { "bartlett", "Bartlett",         0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BARTLETT}, 0, 0, A, "win_func" },
         { "hann",     "Hann",             0, AV_OPT_TYPE_CONST, {.i64=WFUNC_HANNING},  0, 0, A, "win_func" },
         { "hanning",  "Hanning",          0, AV_OPT_TYPE_CONST, {.i64=WFUNC_HANNING},  0, 0, A, "win_func" },
         { "hamming",  "Hamming",          0, AV_OPT_TYPE_CONST, {.i64=WFUNC_HAMMING},  0, 0, A, "win_func" },
         { "blackman", "Blackman",         0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BLACKMAN}, 0, 0, A, "win_func" },
         { "welch",    "Welch",            0, AV_OPT_TYPE_CONST, {.i64=WFUNC_WELCH},    0, 0, A, "win_func" },
         { "flattop",  "Flat-top",         0, AV_OPT_TYPE_CONST, {.i64=WFUNC_FLATTOP},  0, 0, A, "win_func" },
         { "bharris",  "Blackman-Harris",  0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BHARRIS},  0, 0, A, "win_func" },
         { "bnuttall", "Blackman-Nuttall", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BNUTTALL}, 0, 0, A, "win_func" },
         { "bhann",    "Bartlett-Hann",    0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BHANN},    0, 0, A, "win_func" },
         { "sine",     "Sine",             0, AV_OPT_TYPE_CONST, {.i64=WFUNC_SINE},     0, 0, A, "win_func" },
         { "nuttall",  "Nuttall",          0, AV_OPT_TYPE_CONST, {.i64=WFUNC_NUTTALL},  0, 0, A, "win_func" },
         { "lanczos",  "Lanczos",          0, AV_OPT_TYPE_CONST, {.i64=WFUNC_LANCZOS},  0, 0, A, "win_func" },
         { "gauss",    "Gauss",            0, AV_OPT_TYPE_CONST, {.i64=WFUNC_GAUSS},    0, 0, A, "win_func" },
         { "tukey",    "Tukey",            0, AV_OPT_TYPE_CONST, {.i64=WFUNC_TUKEY},    0, 0, A, "win_func" },
         { "dolph",    "Dolph-Chebyshev",  0, AV_OPT_TYPE_CONST, {.i64=WFUNC_DOLPH},    0, 0, A, "win_func" },
         { "cauchy",   "Cauchy",           0, AV_OPT_TYPE_CONST, {.i64=WFUNC_CAUCHY},   0, 0, A, "win_func" },
         { "parzen",   "Parzen",           0, AV_OPT_TYPE_CONST, {.i64=WFUNC_PARZEN},   0, 0, A, "win_func" },
         { "poisson",  "Poisson",          0, AV_OPT_TYPE_CONST, {.i64=WFUNC_POISSON},  0, 0, A, "win_func" },
         { "bohman",   "Bohman",           0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BOHMAN},   0, 0, A, "win_func" },
     { "overlap", "set window overlap", OFFSET(overlap), AV_OPT_TYPE_FLOAT, {.dbl=0.75}, 0,  1, A },
     { NULL },
 };

 AVFILTER_DEFINE_CLASS(afftfilt);

 static inline double getreal(void *priv, double x, double ch)
 {
     AFFTFiltContext *s = priv;
     int ich, ix;

     ich = av_clip(ch, 0, s->nb_exprs - 1);
     ix = av_clip(x, 0, s->window_size / 2);

     return s->fft_data[ich][ix].re;
 }

 static inline double getimag(void *priv, double x, double ch)
 {
     AFFTFiltContext *s = priv;
     int ich, ix;

     ich = av_clip(ch, 0, s->nb_exprs - 1);
     ix = av_clip(x, 0, s->window_size / 2);

     return s->fft_data[ich][ix].im;
 }

 static double realf(void *priv, double x, double ch) { return getreal(priv, x, ch); }
 static double imagf(void *priv, double x, double ch) { return getimag(priv, x, ch); }

 static const char *const func2_names[]    = { "real", "imag", NULL };
 static double (*const func2[])(void *, double, double) = {  realf,  imagf, NULL };

 static int config_input(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;
     AFFTFiltContext *s = ctx->priv;
     char *saveptr = NULL;
     int ret = 0, ch;
     float overlap;
     char *args;
     const char *last_expr = "1";

     s->channels = inlink->channels;
     s->pts  = AV_NOPTS_VALUE;
     s->fft_bits = av_log2(s->fft_size);
     s->fft  = av_fft_init(s->fft_bits, 0);
     s->ifft = av_fft_init(s->fft_bits, 1);
     if (!s->fft || !s->ifft)
         return AVERROR(ENOMEM);

     s->window_size = 1 << s->fft_bits;

     s->fft_data = av_calloc(inlink->channels, sizeof(*s->fft_data));
     if (!s->fft_data)
         return AVERROR(ENOMEM);

     s->fft_temp = av_calloc(inlink->channels, sizeof(*s->fft_temp));
     if (!s->fft_temp)
         return AVERROR(ENOMEM);

     for (ch = 0; ch < inlink->channels; ch++) {
         s->fft_data[ch] = av_calloc(s->window_size, sizeof(**s->fft_data));
         if (!s->fft_data[ch])
             return AVERROR(ENOMEM);
     }

     for (ch = 0; ch < inlink->channels; ch++) {
         s->fft_temp[ch] = av_calloc(s->window_size, sizeof(**s->fft_temp));
         if (!s->fft_temp[ch])
             return AVERROR(ENOMEM);
     }

     s->real = av_calloc(inlink->channels, sizeof(*s->real));
     if (!s->real)
         return AVERROR(ENOMEM);

     s->imag = av_calloc(inlink->channels, sizeof(*s->imag));
     if (!s->imag)
         return AVERROR(ENOMEM);

     args = av_strdup(s->real_str);
     if (!args)
         return AVERROR(ENOMEM);

     for (ch = 0; ch < inlink->channels; ch++) {
         char *arg = av_strtok(ch == 0 ? args : NULL, "|", &saveptr);

         ret = av_expr_parse(&s->real[ch], arg ? arg : last_expr, var_names,
                             NULL, NULL, func2_names, func2, 0, ctx);
         if (ret < 0)
             goto fail;
         if (arg)
             last_expr = arg;
         s->nb_exprs++;
     }

     av_freep(&args);

     args = av_strdup(s->img_str ? s->img_str : s->real_str);
     if (!args)
         return AVERROR(ENOMEM);

     saveptr = NULL;
     last_expr = "1";
     for (ch = 0; ch < inlink->channels; ch++) {
         char *arg = av_strtok(ch == 0 ? args : NULL, "|", &saveptr);

         ret = av_expr_parse(&s->imag[ch], arg ? arg : last_expr, var_names,
                             NULL, NULL, func2_names, func2, 0, ctx);
         if (ret < 0)
             goto fail;
         if (arg)
             last_expr = arg;
     }

     av_freep(&args);

     s->fifo = av_audio_fifo_alloc(inlink->format, inlink->channels, s->window_size);
     if (!s->fifo)
         return AVERROR(ENOMEM);

     s->window_func_lut = av_realloc_f(s->window_func_lut, s->window_size,
                                       sizeof(*s->window_func_lut));
     if (!s->window_func_lut)
         return AVERROR(ENOMEM);
     generate_window_func(s->window_func_lut, s->window_size, s->win_func, &overlap);
     if (s->overlap == 1)
         s->overlap = overlap;

     s->hop_size = s->window_size * (1 - s->overlap);
     if (s->hop_size <= 0)
         return AVERROR(EINVAL);

     s->buffer = ff_get_audio_buffer(inlink, s->window_size * 2);
     if (!s->buffer)
         return AVERROR(ENOMEM);

 fail:
     av_freep(&args);

     return ret;
 }

 static int filter_frame(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;
     AVFilterLink *outlink = ctx->outputs[0];
     AFFTFiltContext *s = ctx->priv;
     const int window_size = s->window_size;
     const float f = 1. / (s->window_size / 2);
     double values[VAR_VARS_NB];
     AVFrame *out, *in = NULL;
     int ch, n, ret, i;

     if (!in) {
         in = ff_get_audio_buffer(outlink, window_size);
         if (!in)
             return AVERROR(ENOMEM);
     }

     ret = av_audio_fifo_peek(s->fifo, (void **)in->extended_data, window_size);
     if (ret < 0)
         goto fail;

     for (ch = 0; ch < inlink->channels; ch++) {
         const float *src = (float *)in->extended_data[ch];
         FFTComplex *fft_data = s->fft_data[ch];

         for (n = 0; n < in->nb_samples; n++) {
             fft_data[n].re = src[n] * s->window_func_lut[n];
             fft_data[n].im = 0;
         }

         for (; n < window_size; n++) {
             fft_data[n].re = 0;
             fft_data[n].im = 0;
         }
     }

     values[VAR_PTS]         = s->pts;
     values[VAR_SAMPLE_RATE] = inlink->sample_rate;
     values[VAR_NBBINS]      = window_size / 2;
     values[VAR_CHANNELS]    = inlink->channels;

     for (ch = 0; ch < inlink->channels; ch++) {
         FFTComplex *fft_data = s->fft_data[ch];

         av_fft_permute(s->fft, fft_data);
         av_fft_calc(s->fft, fft_data);
     }

     for (ch = 0; ch < inlink->channels; ch++) {
         FFTComplex *fft_data = s->fft_data[ch];
         FFTComplex *fft_temp = s->fft_temp[ch];
         float *buf = (float *)s->buffer->extended_data[ch];
         int x;
         values[VAR_CHANNEL] = ch;

         for (n = 0; n <= window_size / 2; n++) {
             float fr, fi;

             values[VAR_BIN] = n;
             values[VAR_REAL] = fft_data[n].re;
             values[VAR_IMAG] = fft_data[n].im;

             fr = av_expr_eval(s->real[ch], values, s);
             fi = av_expr_eval(s->imag[ch], values, s);

             fft_temp[n].re = fr;
             fft_temp[n].im = fi;
         }

         for (n = window_size / 2 + 1, x = window_size / 2 - 1; n < window_size; n++, x--) {
             fft_temp[n].re =  fft_temp[x].re;
             fft_temp[n].im = -fft_temp[x].im;
         }

         av_fft_permute(s->ifft, fft_temp);
         av_fft_calc(s->ifft, fft_temp);

         for (i = 0; i < window_size; i++) {
             buf[i] += s->fft_temp[ch][i].re * f;
         }
     }

     out = ff_get_audio_buffer(outlink, s->hop_size);
     if (!out) {
         ret = AVERROR(ENOMEM);
         goto fail;
     }

     out->pts = s->pts;
     s->pts += av_rescale_q(s->hop_size, (AVRational){1, outlink->sample_rate}, outlink->time_base);

     for (ch = 0; ch < inlink->channels; ch++) {
         float *dst = (float *)out->extended_data[ch];
         float *buf = (float *)s->buffer->extended_data[ch];

         for (n = 0; n < s->hop_size; n++)
             dst[n] = buf[n] * (1.f - s->overlap);
         memmove(buf, buf + s->hop_size, window_size * 4);
     }

     ret = ff_filter_frame(outlink, out);
     if (ret < 0)
         goto fail;

     av_audio_fifo_drain(s->fifo, s->hop_size);

 fail:
     av_frame_free(&in);
     return ret < 0 ? ret : 0;
 }

 static int activate(AVFilterContext *ctx)
 {
     AVFilterLink *inlink = ctx->inputs[0];
     AVFilterLink *outlink = ctx->outputs[0];
     AFFTFiltContext *s = ctx->priv;
     AVFrame *in = NULL;
     int ret = 0, status;
     int64_t pts;

     FF_FILTER_FORWARD_STATUS_BACK(outlink, inlink);

     if (!s->eof && av_audio_fifo_size(s->fifo) < s->window_size) {
         ret = ff_inlink_consume_frame(inlink, &in);
         if (ret < 0)
             return ret;

         if (ret > 0) {
             ret = av_audio_fifo_write(s->fifo, (void **)in->extended_data,
                                       in->nb_samples);
             if (ret >= 0 && s->pts == AV_NOPTS_VALUE)
                 s->pts = in->pts;

             av_frame_free(&in);
             if (ret < 0)
                 return ret;
         }
     }

     if ((av_audio_fifo_size(s->fifo) >= s->window_size) ||
         (av_audio_fifo_size(s->fifo) > 0 && s->eof)) {
         ret = filter_frame(inlink);
         if (av_audio_fifo_size(s->fifo) >= s->window_size)
             ff_filter_set_ready(ctx, 100);
         return ret;
     }

     if (!s->eof && ff_inlink_acknowledge_status(inlink, &status, &pts)) {
         if (status == AVERROR_EOF) {
             s->eof = 1;
             if (av_audio_fifo_size(s->fifo) >= 0) {
                 ff_filter_set_ready(ctx, 100);
                 return 0;
             }
         }
     }

     if (s->eof && av_audio_fifo_size(s->fifo) <= 0) {
         ff_outlink_set_status(outlink, AVERROR_EOF, s->pts);
         return 0;
     }

     if (!s->eof)
         FF_FILTER_FORWARD_WANTED(outlink, inlink);

     return FFERROR_NOT_READY;
 }

 static int query_formats(AVFilterContext *ctx)
 {
     AVFilterFormats *formats;
     AVFilterChannelLayouts *layouts;
     static const enum AVSampleFormat sample_fmts[] = {
         AV_SAMPLE_FMT_FLTP,
         AV_SAMPLE_FMT_NONE
     };
     int 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_make_format_list(sample_fmts);
     if (!formats)
         return AVERROR(ENOMEM);
     ret = ff_set_common_formats(ctx, formats);
     if (ret < 0)
         return ret;

     formats = ff_all_samplerates();
     if (!formats)
         return AVERROR(ENOMEM);
     return ff_set_common_samplerates(ctx, formats);
 }

 static av_cold void uninit(AVFilterContext *ctx)
 {
     AFFTFiltContext *s = ctx->priv;
     int i;

     av_fft_end(s->fft);
     av_fft_end(s->ifft);

     for (i = 0; i < s->channels; i++) {
         if (s->fft_data)
             av_freep(&s->fft_data[i]);
         if (s->fft_temp)
             av_freep(&s->fft_temp[i]);
     }
     av_freep(&s->fft_data);
     av_freep(&s->fft_temp);

     for (i = 0; i < s->nb_exprs; i++) {
         av_expr_free(s->real[i]);
         av_expr_free(s->imag[i]);
     }

     av_freep(&s->real);
     av_freep(&s->imag);
     av_frame_free(&s->buffer);
     av_freep(&s->window_func_lut);

     av_audio_fifo_free(s->fifo);
 }

 static const AVFilterPad inputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_AUDIO,
         .config_props = config_input,
     },
     { NULL }
 };

 static const AVFilterPad outputs[] = {
     {
         .name = "default",
         .type = AVMEDIA_TYPE_AUDIO,
     },
     { NULL }
 };

 AVFilter ff_af_afftfilt = {
     .name            = "afftfilt",
     .description     = NULL_IF_CONFIG_SMALL("Apply arbitrary expressions to samples in frequency domain."),
     .priv_size       = sizeof(AFFTFiltContext),
     .priv_class      = &afftfilt_class,
     .inputs          = inputs,
     .outputs         = outputs,
     .activate        = activate,
     .query_formats   = query_formats,
     .uninit          = uninit,
 };
	/*
	* Copyright (c) 2016 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/audio_fifo.h"
	#include "libavutil/avstring.h"
	#include "libavfilter/internal.h"
	#include "libavutil/common.h"
	#include "libavutil/opt.h"
	#include "libavcodec/avfft.h"
	#include "libavutil/eval.h"
	#include "audio.h"
	#include "filters.h"
	#include "window_func.h"

	typedef struct AFFTFiltContext {
	const AVClass *class;
	char *real_str;
	char *img_str;
	int fft_size;
	int fft_bits;

	FFTContext fft, ifft;
	FFTComplex **fft_data;
	FFTComplex **fft_temp;
	int nb_exprs;
	int channels;
	int window_size;
	AVExpr **real;
	AVExpr **imag;
	AVAudioFifo *fifo;
	int64_t pts;
	int hop_size;
	float overlap;
	AVFrame *buffer;
	int eof;
	int win_func;
	float *window_func_lut;
	} AFFTFiltContext;

	static const char *const var_names[] = { "sr", "b", "nb", "ch", "chs", "pts", "re", "im", NULL };
	enum { VAR_SAMPLE_RATE, VAR_BIN, VAR_NBBINS, VAR_CHANNEL, VAR_CHANNELS, VAR_PTS, VAR_REAL, VAR_IMAG, VAR_VARS_NB };

	#define OFFSET(x) offsetof(AFFTFiltContext, x)
	#define A AV_OPT_FLAG_AUDIO_PARAM\|AV_OPT_FLAG_FILTERING_PARAM

	static const AVOption afftfilt_options[] = {
	{ "real", "set channels real expressions", OFFSET(real_str), AV_OPT_TYPE_STRING, {.str = "re" }, 0, 0, A },
	{ "imag", "set channels imaginary expressions", OFFSET(img_str), AV_OPT_TYPE_STRING, {.str = "im" }, 0, 0, A },
	{ "win_size", "set window size", OFFSET(fft_size), AV_OPT_TYPE_INT, {.i64=4096}, 16, 131072, A },
	{ "win_func", "set window function", OFFSET(win_func), AV_OPT_TYPE_INT, {.i64 = WFUNC_HANNING}, 0, NB_WFUNC-1, A, "win_func" },
	{ "rect", "Rectangular", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_RECT}, 0, 0, A, "win_func" },
	{ "bartlett", "Bartlett", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BARTLETT}, 0, 0, A, "win_func" },
	{ "hann", "Hann", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_HANNING}, 0, 0, A, "win_func" },
	{ "hanning", "Hanning", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_HANNING}, 0, 0, A, "win_func" },
	{ "hamming", "Hamming", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_HAMMING}, 0, 0, A, "win_func" },
	{ "blackman", "Blackman", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BLACKMAN}, 0, 0, A, "win_func" },
	{ "welch", "Welch", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_WELCH}, 0, 0, A, "win_func" },
	{ "flattop", "Flat-top", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_FLATTOP}, 0, 0, A, "win_func" },
	{ "bharris", "Blackman-Harris", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BHARRIS}, 0, 0, A, "win_func" },
	{ "bnuttall", "Blackman-Nuttall", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BNUTTALL}, 0, 0, A, "win_func" },
	{ "bhann", "Bartlett-Hann", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BHANN}, 0, 0, A, "win_func" },
	{ "sine", "Sine", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_SINE}, 0, 0, A, "win_func" },
	{ "nuttall", "Nuttall", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_NUTTALL}, 0, 0, A, "win_func" },
	{ "lanczos", "Lanczos", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_LANCZOS}, 0, 0, A, "win_func" },
	{ "gauss", "Gauss", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_GAUSS}, 0, 0, A, "win_func" },
	{ "tukey", "Tukey", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_TUKEY}, 0, 0, A, "win_func" },
	{ "dolph", "Dolph-Chebyshev", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_DOLPH}, 0, 0, A, "win_func" },
	{ "cauchy", "Cauchy", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_CAUCHY}, 0, 0, A, "win_func" },
	{ "parzen", "Parzen", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_PARZEN}, 0, 0, A, "win_func" },
	{ "poisson", "Poisson", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_POISSON}, 0, 0, A, "win_func" },
	{ "bohman", "Bohman", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BOHMAN}, 0, 0, A, "win_func" },
	{ "overlap", "set window overlap", OFFSET(overlap), AV_OPT_TYPE_FLOAT, {.dbl=0.75}, 0, 1, A },
	{ NULL },
	};

	AVFILTER_DEFINE_CLASS(afftfilt);

	static inline double getreal(void *priv, double x, double ch)
	{
	AFFTFiltContext *s = priv;
	int ich, ix;

	ich = av_clip(ch, 0, s->nb_exprs - 1);
	ix = av_clip(x, 0, s->window_size / 2);

	return s->fft_data[ich][ix].re;
	}

	static inline double getimag(void *priv, double x, double ch)
	{
	AFFTFiltContext *s = priv;
	int ich, ix;

	ich = av_clip(ch, 0, s->nb_exprs - 1);
	ix = av_clip(x, 0, s->window_size / 2);

	return s->fft_data[ich][ix].im;
	}

	static double realf(void *priv, double x, double ch) { return getreal(priv, x, ch); }
	static double imagf(void *priv, double x, double ch) { return getimag(priv, x, ch); }

	static const char *const func2_names[] = { "real", "imag", NULL };
	static double (const func2[])(void , double, double) = { realf, imagf, NULL };

	static int config_input(AVFilterLink *inlink)
	{
	AVFilterContext *ctx = inlink->dst;
	AFFTFiltContext *s = ctx->priv;
	char *saveptr = NULL;
	int ret = 0, ch;
	float overlap;
	char *args;
	const char *last_expr = "1";

	s->channels = inlink->channels;
	s->pts = AV_NOPTS_VALUE;
	s->fft_bits = av_log2(s->fft_size);
	s->fft = av_fft_init(s->fft_bits, 0);
	s->ifft = av_fft_init(s->fft_bits, 1);
	if (!s->fft \|\| !s->ifft)
	return AVERROR(ENOMEM);

	s->window_size = 1 << s->fft_bits;

	s->fft_data = av_calloc(inlink->channels, sizeof(*s->fft_data));
	if (!s->fft_data)
	return AVERROR(ENOMEM);

	s->fft_temp = av_calloc(inlink->channels, sizeof(*s->fft_temp));
	if (!s->fft_temp)
	return AVERROR(ENOMEM);

	for (ch = 0; ch < inlink->channels; ch++) {
	s->fft_data[ch] = av_calloc(s->window_size, sizeof(**s->fft_data));
	if (!s->fft_data[ch])
	return AVERROR(ENOMEM);
	}

	for (ch = 0; ch < inlink->channels; ch++) {
	s->fft_temp[ch] = av_calloc(s->window_size, sizeof(**s->fft_temp));
	if (!s->fft_temp[ch])
	return AVERROR(ENOMEM);
	}

	s->real = av_calloc(inlink->channels, sizeof(*s->real));
	if (!s->real)
	return AVERROR(ENOMEM);

	s->imag = av_calloc(inlink->channels, sizeof(*s->imag));
	if (!s->imag)
	return AVERROR(ENOMEM);

	args = av_strdup(s->real_str);
	if (!args)
	return AVERROR(ENOMEM);

	for (ch = 0; ch < inlink->channels; ch++) {
	char *arg = av_strtok(ch == 0 ? args : NULL, "\|", &saveptr);

	ret = av_expr_parse(&s->real[ch], arg ? arg : last_expr, var_names,
	NULL, NULL, func2_names, func2, 0, ctx);
	if (ret < 0)
	goto fail;
	if (arg)
	last_expr = arg;
	s->nb_exprs++;
	}

	av_freep(&args);

	args = av_strdup(s->img_str ? s->img_str : s->real_str);
	if (!args)
	return AVERROR(ENOMEM);

	saveptr = NULL;
	last_expr = "1";
	for (ch = 0; ch < inlink->channels; ch++) {
	char *arg = av_strtok(ch == 0 ? args : NULL, "\|", &saveptr);

	ret = av_expr_parse(&s->imag[ch], arg ? arg : last_expr, var_names,
	NULL, NULL, func2_names, func2, 0, ctx);
	if (ret < 0)
	goto fail;
	if (arg)
	last_expr = arg;
	}

	av_freep(&args);

	s->fifo = av_audio_fifo_alloc(inlink->format, inlink->channels, s->window_size);
	if (!s->fifo)
	return AVERROR(ENOMEM);

	s->window_func_lut = av_realloc_f(s->window_func_lut, s->window_size,
	sizeof(*s->window_func_lut));
	if (!s->window_func_lut)
	return AVERROR(ENOMEM);
	generate_window_func(s->window_func_lut, s->window_size, s->win_func, &overlap);
	if (s->overlap == 1)
	s->overlap = overlap;

	s->hop_size = s->window_size * (1 - s->overlap);
	if (s->hop_size <= 0)
	return AVERROR(EINVAL);

	s->buffer = ff_get_audio_buffer(inlink, s->window_size * 2);
	if (!s->buffer)
	return AVERROR(ENOMEM);

	fail:
	av_freep(&args);

	return ret;
	}

	static int filter_frame(AVFilterLink *inlink)
	{
	AVFilterContext *ctx = inlink->dst;
	AVFilterLink *outlink = ctx->outputs[0];
	AFFTFiltContext *s = ctx->priv;
	const int window_size = s->window_size;
	const float f = 1. / (s->window_size / 2);
	double values[VAR_VARS_NB];
	AVFrame out, in = NULL;
	int ch, n, ret, i;

	if (!in) {
	in = ff_get_audio_buffer(outlink, window_size);
	if (!in)
	return AVERROR(ENOMEM);
	}

	ret = av_audio_fifo_peek(s->fifo, (void **)in->extended_data, window_size);
	if (ret < 0)
	goto fail;

	for (ch = 0; ch < inlink->channels; ch++) {
	const float src = (float )in->extended_data[ch];
	FFTComplex *fft_data = s->fft_data[ch];

	for (n = 0; n < in->nb_samples; n++) {
	fft_data[n].re = src[n] * s->window_func_lut[n];
	fft_data[n].im = 0;
	}

	for (; n < window_size; n++) {
	fft_data[n].re = 0;
	fft_data[n].im = 0;
	}
	}

	values[VAR_PTS] = s->pts;
	values[VAR_SAMPLE_RATE] = inlink->sample_rate;
	values[VAR_NBBINS] = window_size / 2;
	values[VAR_CHANNELS] = inlink->channels;

	for (ch = 0; ch < inlink->channels; ch++) {
	FFTComplex *fft_data = s->fft_data[ch];

	av_fft_permute(s->fft, fft_data);
	av_fft_calc(s->fft, fft_data);
	}

	for (ch = 0; ch < inlink->channels; ch++) {
	FFTComplex *fft_data = s->fft_data[ch];
	FFTComplex *fft_temp = s->fft_temp[ch];
	float buf = (float )s->buffer->extended_data[ch];
	int x;
	values[VAR_CHANNEL] = ch;

	for (n = 0; n <= window_size / 2; n++) {
	float fr, fi;

	values[VAR_BIN] = n;
	values[VAR_REAL] = fft_data[n].re;
	values[VAR_IMAG] = fft_data[n].im;

	fr = av_expr_eval(s->real[ch], values, s);
	fi = av_expr_eval(s->imag[ch], values, s);

	fft_temp[n].re = fr;
	fft_temp[n].im = fi;
	}

	for (n = window_size / 2 + 1, x = window_size / 2 - 1; n < window_size; n++, x--) {
	fft_temp[n].re = fft_temp[x].re;
	fft_temp[n].im = -fft_temp[x].im;
	}

	av_fft_permute(s->ifft, fft_temp);
	av_fft_calc(s->ifft, fft_temp);

	for (i = 0; i < window_size; i++) {
	buf[i] += s->fft_temp[ch][i].re * f;
	}
	}

	out = ff_get_audio_buffer(outlink, s->hop_size);
	if (!out) {
	ret = AVERROR(ENOMEM);
	goto fail;
	}

	out->pts = s->pts;
	s->pts += av_rescale_q(s->hop_size, (AVRational){1, outlink->sample_rate}, outlink->time_base);

	for (ch = 0; ch < inlink->channels; ch++) {
	float dst = (float )out->extended_data[ch];
	float buf = (float )s->buffer->extended_data[ch];

	for (n = 0; n < s->hop_size; n++)
	dst[n] = buf[n] * (1.f - s->overlap);
	memmove(buf, buf + s->hop_size, window_size * 4);
	}

	ret = ff_filter_frame(outlink, out);
	if (ret < 0)
	goto fail;

	av_audio_fifo_drain(s->fifo, s->hop_size);

	fail:
	av_frame_free(&in);
	return ret < 0 ? ret : 0;
	}

	static int activate(AVFilterContext *ctx)
	{
	AVFilterLink *inlink = ctx->inputs[0];
	AVFilterLink *outlink = ctx->outputs[0];
	AFFTFiltContext *s = ctx->priv;
	AVFrame *in = NULL;
	int ret = 0, status;
	int64_t pts;

	FF_FILTER_FORWARD_STATUS_BACK(outlink, inlink);

	if (!s->eof && av_audio_fifo_size(s->fifo) < s->window_size) {
	ret = ff_inlink_consume_frame(inlink, &in);
	if (ret < 0)
	return ret;

	if (ret > 0) {
	ret = av_audio_fifo_write(s->fifo, (void **)in->extended_data,
	in->nb_samples);
	if (ret >= 0 && s->pts == AV_NOPTS_VALUE)
	s->pts = in->pts;

	av_frame_free(&in);
	if (ret < 0)
	return ret;
	}
	}

	if ((av_audio_fifo_size(s->fifo) >= s->window_size) \|\|
	(av_audio_fifo_size(s->fifo) > 0 && s->eof)) {
	ret = filter_frame(inlink);
	if (av_audio_fifo_size(s->fifo) >= s->window_size)
	ff_filter_set_ready(ctx, 100);
	return ret;
	}

	if (!s->eof && ff_inlink_acknowledge_status(inlink, &status, &pts)) {
	if (status == AVERROR_EOF) {
	s->eof = 1;
	if (av_audio_fifo_size(s->fifo) >= 0) {
	ff_filter_set_ready(ctx, 100);
	return 0;
	}
	}
	}

	if (s->eof && av_audio_fifo_size(s->fifo) <= 0) {
	ff_outlink_set_status(outlink, AVERROR_EOF, s->pts);
	return 0;
	}

	if (!s->eof)
	FF_FILTER_FORWARD_WANTED(outlink, inlink);

	return FFERROR_NOT_READY;
	}

	static int query_formats(AVFilterContext *ctx)
	{
	AVFilterFormats *formats;
	AVFilterChannelLayouts *layouts;
	static const enum AVSampleFormat sample_fmts[] = {
	AV_SAMPLE_FMT_FLTP,
	AV_SAMPLE_FMT_NONE
	};
	int 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_make_format_list(sample_fmts);
	if (!formats)
	return AVERROR(ENOMEM);
	ret = ff_set_common_formats(ctx, formats);
	if (ret < 0)
	return ret;

	formats = ff_all_samplerates();
	if (!formats)
	return AVERROR(ENOMEM);
	return ff_set_common_samplerates(ctx, formats);
	}

	static av_cold void uninit(AVFilterContext *ctx)
	{
	AFFTFiltContext *s = ctx->priv;
	int i;

	av_fft_end(s->fft);
	av_fft_end(s->ifft);

	for (i = 0; i < s->channels; i++) {
	if (s->fft_data)
	av_freep(&s->fft_data[i]);
	if (s->fft_temp)
	av_freep(&s->fft_temp[i]);
	}
	av_freep(&s->fft_data);
	av_freep(&s->fft_temp);

	for (i = 0; i < s->nb_exprs; i++) {
	av_expr_free(s->real[i]);
	av_expr_free(s->imag[i]);
	}

	av_freep(&s->real);
	av_freep(&s->imag);
	av_frame_free(&s->buffer);
	av_freep(&s->window_func_lut);

	av_audio_fifo_free(s->fifo);
	}

	static const AVFilterPad inputs[] = {
	{
	.name = "default",
	.type = AVMEDIA_TYPE_AUDIO,
	.config_props = config_input,
	},
	{ NULL }
	};

	static const AVFilterPad outputs[] = {
	{
	.name = "default",
	.type = AVMEDIA_TYPE_AUDIO,
	},
	{ NULL }
	};

	AVFilter ff_af_afftfilt = {
	.name = "afftfilt",
	.description = NULL_IF_CONFIG_SMALL("Apply arbitrary expressions to samples in frequency domain."),
	.priv_size = sizeof(AFFTFiltContext),
	.priv_class = &afftfilt_class,
	.inputs = inputs,
	.outputs = outputs,
	.activate = activate,
	.query_formats = query_formats,
	.uninit = uninit,
	};