261 lines
8.6 KiB
C
261 lines
8.6 KiB
C
/*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "libavutil/channel_layout.h"
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#include "libavutil/ffmath.h"
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#include "libavutil/opt.h"
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#include "avfilter.h"
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#include "audio.h"
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#define MAX_ORDER 30
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typedef struct Coeffs {
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double g;
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double a1;
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double b0, b1;
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} Coeffs;
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typedef struct ATiltContext {
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const AVClass *class;
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double freq;
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double level;
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double slope;
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double width;
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int order;
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Coeffs coeffs[MAX_ORDER];
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AVFrame *w;
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int (*filter_channels)(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs);
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} ATiltContext;
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static double prewarp(double w, double T, double wp)
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{
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return wp * tan(w * T * 0.5) / tan(wp * T * 0.5);
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}
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static double mz(int i, double w0, double r, double alpha)
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{
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return w0 * pow(r, -alpha + i);
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}
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static double mp(int i, double w0, double r)
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{
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return w0 * pow(r, i);
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}
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static double mzh(int i, double T, double w0, double r, double alpha)
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{
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return prewarp(mz(i, w0, r, alpha), T, w0);
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}
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static double mph(int i, double T, double w0, double r)
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{
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return prewarp(mp(i, w0, r), T, w0);
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}
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static void set_tf1s(Coeffs *coeffs, double b1, double b0, double a0,
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double w1, double sr, double alpha)
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{
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double c = 1.0 / tan(w1 * 0.5 / sr);
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double d = a0 + c;
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coeffs->b1 = (b0 - b1 * c) / d;
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coeffs->b0 = (b0 + b1 * c) / d;
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coeffs->a1 = (a0 - c) / d;
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coeffs->g = a0 / b0;
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}
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static void set_filter(AVFilterContext *ctx,
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int order, double sr, double f0,
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double bw, double alpha)
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{
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ATiltContext *s = ctx->priv;
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const double w0 = 2. * M_PI * f0;
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const double f1 = f0 + bw;
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const double w1 = 1.;
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const double r = pow(f1 / f0, 1.0 / (order - 1.0));
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const double T = 1. / sr;
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for (int i = 0; i < order; i++) {
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Coeffs *coeffs = &s->coeffs[i];
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set_tf1s(coeffs, 1.0, mzh(i, T, w0, r, alpha), mph(i, T, w0, r),
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w1, sr, alpha);
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}
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}
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static int get_coeffs(AVFilterContext *ctx)
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{
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ATiltContext *s = ctx->priv;
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AVFilterLink *inlink = ctx->inputs[0];
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set_filter(ctx, s->order, inlink->sample_rate, s->freq, s->width, s->slope);
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return 0;
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}
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typedef struct ThreadData {
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AVFrame *in, *out;
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} ThreadData;
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#define FILTER(name, type) \
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static int filter_channels_## name(AVFilterContext *ctx, void *arg, \
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int jobnr, int nb_jobs) \
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{ \
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ATiltContext *s = ctx->priv; \
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ThreadData *td = arg; \
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AVFrame *out = td->out; \
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AVFrame *in = td->in; \
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const int start = (in->ch_layout.nb_channels * jobnr) / nb_jobs; \
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const int end = (in->ch_layout.nb_channels * (jobnr+1)) / nb_jobs; \
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const type level = s->level; \
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\
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for (int ch = start; ch < end; ch++) { \
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const type *src = (const type *)in->extended_data[ch]; \
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type *dst = (type *)out->extended_data[ch]; \
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\
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for (int b = 0; b < s->order; b++) { \
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Coeffs *coeffs = &s->coeffs[b]; \
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const type g = coeffs->g; \
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const type a1 = coeffs->a1; \
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const type b0 = coeffs->b0; \
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const type b1 = coeffs->b1; \
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type *w = ((type *)s->w->extended_data[ch]) + b * 2; \
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\
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for (int n = 0; n < in->nb_samples; n++) { \
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type sain = b ? dst[n] : src[n] * level; \
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type saout = sain * b0 + w[0] * b1 - w[1] * a1; \
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\
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w[0] = sain; \
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w[1] = saout; \
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\
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dst[n] = saout * g; \
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} \
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} \
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} \
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\
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return 0; \
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}
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FILTER(fltp, float)
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FILTER(dblp, double)
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static int config_input(AVFilterLink *inlink)
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{
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AVFilterContext *ctx = inlink->dst;
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ATiltContext *s = ctx->priv;
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switch (inlink->format) {
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case AV_SAMPLE_FMT_FLTP: s->filter_channels = filter_channels_fltp; break;
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case AV_SAMPLE_FMT_DBLP: s->filter_channels = filter_channels_dblp; break;
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}
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s->w = ff_get_audio_buffer(inlink, 2 * MAX_ORDER);
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if (!s->w)
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return AVERROR(ENOMEM);
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return get_coeffs(ctx);
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}
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static int filter_frame(AVFilterLink *inlink, AVFrame *in)
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{
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AVFilterContext *ctx = inlink->dst;
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ATiltContext *s = ctx->priv;
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AVFilterLink *outlink = ctx->outputs[0];
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ThreadData td;
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AVFrame *out;
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if (av_frame_is_writable(in)) {
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out = in;
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} else {
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out = ff_get_audio_buffer(outlink, in->nb_samples);
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if (!out) {
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av_frame_free(&in);
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return AVERROR(ENOMEM);
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}
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av_frame_copy_props(out, in);
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}
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td.in = in; td.out = out;
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ff_filter_execute(ctx, s->filter_channels, &td, NULL, FFMIN(inlink->ch_layout.nb_channels,
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ff_filter_get_nb_threads(ctx)));
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if (out != in)
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av_frame_free(&in);
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return ff_filter_frame(outlink, out);
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}
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static int process_command(AVFilterContext *ctx, const char *cmd, const char *args,
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char *res, int res_len, int flags)
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{
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int ret;
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ret = ff_filter_process_command(ctx, cmd, args, res, res_len, flags);
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if (ret < 0)
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return ret;
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return get_coeffs(ctx);
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}
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static av_cold void uninit(AVFilterContext *ctx)
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{
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ATiltContext *s = ctx->priv;
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av_frame_free(&s->w);
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}
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#define OFFSET(x) offsetof(ATiltContext, x)
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#define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_RUNTIME_PARAM
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static const AVOption atilt_options[] = {
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{ "freq", "set central frequency",OFFSET(freq), AV_OPT_TYPE_DOUBLE, {.dbl=10000}, 20, 192000, FLAGS },
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{ "slope", "set filter slope", OFFSET(slope), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -1, 1, FLAGS },
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{ "width", "set filter width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=1000}, 100, 10000, FLAGS },
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{ "order", "set filter order", OFFSET(order), AV_OPT_TYPE_INT, {.i64=5}, 2,MAX_ORDER, FLAGS },
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{ "level", "set input level", OFFSET(level), AV_OPT_TYPE_DOUBLE, {.dbl=1.}, 0., 4., FLAGS },
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{ NULL }
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};
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AVFILTER_DEFINE_CLASS(atilt);
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static const AVFilterPad inputs[] = {
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{
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.name = "default",
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.type = AVMEDIA_TYPE_AUDIO,
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.filter_frame = filter_frame,
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.config_props = config_input,
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},
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};
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const AVFilter ff_af_atilt = {
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.name = "atilt",
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.description = NULL_IF_CONFIG_SMALL("Apply spectral tilt to audio."),
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.priv_size = sizeof(ATiltContext),
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.priv_class = &atilt_class,
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.uninit = uninit,
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FILTER_INPUTS(inputs),
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FILTER_OUTPUTS(ff_audio_default_filterpad),
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FILTER_SAMPLEFMTS(AV_SAMPLE_FMT_FLTP, AV_SAMPLE_FMT_DBLP),
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.process_command = process_command,
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.flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC |
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AVFILTER_FLAG_SLICE_THREADS,
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};
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