text: /*
   * Copyright (C) 2001-2010 Krzysztof Foltman, Markus Schmidt, Thor Harald Johansen, Damien Zammit
   *
   * 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
   */
  
  /**
   * @file
   * Audio (Sidechain) Gate filter
   */
  
  #include "libavutil/audio_fifo.h"
  #include "libavutil/avassert.h"
  #include "libavutil/channel_layout.h"
  #include "libavutil/opt.h"
  #include "avfilter.h"
  #include "audio.h"
  #include "filters.h"
  #include "formats.h"
  #include "hermite.h"
  
  typedef struct AudioGateContext {
      const AVClass *class;
  
      double level_in;
      double level_sc;
      double attack;
      double release;
      double threshold;
      double ratio;
      double knee;
      double makeup;
      double range;
      int link;
      int detection;
      int mode;
  
      double thres;
      double knee_start;
      double knee_stop;
      double lin_knee_start;
      double lin_knee_stop;
      double lin_slope;
      double attack_coeff;
      double release_coeff;
  
      AVAudioFifo *fifo[2];
      int64_t pts;
  } AudioGateContext;
  
  #define OFFSET(x) offsetof(AudioGateContext, x)
  #define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
  
  static const AVOption options[] = {
      { "level_in",  "set input level",        OFFSET(level_in),  AV_OPT_TYPE_DOUBLE, {.dbl=1},           0.015625,   64, A },
      { "mode",      "set mode",               OFFSET(mode),      AV_OPT_TYPE_INT,    {.i64=0},           0, 1, A, "mode" },
      {   "downward",0,                        0,                 AV_OPT_TYPE_CONST,  {.i64=0},           0, 0, A, "mode" },
      {   "upward",  0,                        0,                 AV_OPT_TYPE_CONST,  {.i64=1},           0, 0, A, "mode" },
      { "range",     "set max gain reduction", OFFSET(range),     AV_OPT_TYPE_DOUBLE, {.dbl=0.06125},     0, 1, A },
      { "threshold", "set threshold",          OFFSET(threshold), AV_OPT_TYPE_DOUBLE, {.dbl=0.125},       0, 1, A },
      { "ratio",     "set ratio",              OFFSET(ratio),     AV_OPT_TYPE_DOUBLE, {.dbl=2},           1,  9000, A },
      { "attack",    "set attack",             OFFSET(attack),    AV_OPT_TYPE_DOUBLE, {.dbl=20},          0.01, 9000, A },
      { "release",   "set release",            OFFSET(release),   AV_OPT_TYPE_DOUBLE, {.dbl=250},         0.01, 9000, A },
      { "makeup",    "set makeup gain",        OFFSET(makeup),    AV_OPT_TYPE_DOUBLE, {.dbl=1},           1,   64, A },
      { "knee",      "set knee",               OFFSET(knee),      AV_OPT_TYPE_DOUBLE, {.dbl=2.828427125}, 1,    8, A },
      { "detection", "set detection",          OFFSET(detection), AV_OPT_TYPE_INT,    {.i64=1},           0,    1, A, "detection" },
      {   "peak",    0,                        0,                 AV_OPT_TYPE_CONST,  {.i64=0},           0,    0, A, "detection" },
      {   "rms",     0,                        0,                 AV_OPT_TYPE_CONST,  {.i64=1},           0,    0, A, "detection" },
      { "link",      "set link",               OFFSET(link),      AV_OPT_TYPE_INT,    {.i64=0},           0,    1, A, "link" },
      {   "average", 0,                        0,                 AV_OPT_TYPE_CONST,  {.i64=0},           0,    0, A, "link" },
      {   "maximum", 0,                        0,                 AV_OPT_TYPE_CONST,  {.i64=1},           0,    0, A, "link" },
      { "level_sc",  "set sidechain gain",     OFFSET(level_sc),  AV_OPT_TYPE_DOUBLE, {.dbl=1},           0.015625,   64, A },
      { NULL }
  };
  
  static int agate_config_input(AVFilterLink *inlink)
  {
      AVFilterContext *ctx = inlink->dst;
      AudioGateContext *s = ctx->priv;
      double lin_threshold = s->threshold;
      double lin_knee_sqrt = sqrt(s->knee);
  
      if (s->detection)
          lin_threshold *= lin_threshold;
  
      s->attack_coeff  = FFMIN(1., 1. / (s->attack * inlink->sample_rate / 4000.));
      s->release_coeff = FFMIN(1., 1. / (s->release * inlink->sample_rate / 4000.));
      s->lin_knee_stop = lin_threshold * lin_knee_sqrt;
      s->lin_knee_start = lin_threshold / lin_knee_sqrt;
      s->thres = log(lin_threshold);
      s->knee_start = log(s->lin_knee_start);
      s->knee_stop = log(s->lin_knee_stop);
  
      return 0;
  }
  
  // A fake infinity value (because real infinity may break some hosts)
  #define FAKE_INFINITY (65536.0 * 65536.0)
  
  // Check for infinity (with appropriate-ish tolerance)
  #define IS_FAKE_INFINITY(value) (fabs(value-FAKE_INFINITY) < 1.0)
  
  static double output_gain(double lin_slope, double ratio, double thres,
                            double knee, double knee_start, double knee_stop,
                            double range, int mode)
  {
      double slope = log(lin_slope);
      double tratio = ratio;
      double gain = 0.;
      double delta = 0.;
  
      if (IS_FAKE_INFINITY(ratio))
          tratio = 1000.;
      gain = (slope - thres) * tratio + thres;
      delta = tratio;
  
      if (mode) {
          if (knee > 1. && slope < knee_stop)
              gain = hermite_interpolation(slope, knee_stop, knee_start, ((knee_stop - thres) * tratio  + thres), knee_start, delta, 1.);
      } else {
          if (knee > 1. && slope > knee_start)
              gain = hermite_interpolation(slope, knee_start, knee_stop, ((knee_start - thres) * tratio  + thres), knee_stop, delta, 1.);
      }
      return FFMAX(range, exp(gain - slope));
  }
  
  static void gate(AudioGateContext *s,
                   const double *src, double *dst, const double *scsrc,
                   int nb_samples, double level_in, double level_sc,
                   AVFilterLink *inlink, AVFilterLink *sclink)
  {
      const double makeup = s->makeup;
      const double attack_coeff = s->attack_coeff;
      const double release_coeff = s->release_coeff;
      int n, c;
  
      for (n = 0; n < nb_samples; n++, src += inlink->channels, dst += inlink->channels, scsrc += sclink->channels) {
          double abs_sample = fabs(scsrc[0] * level_sc), gain = 1.0;
          int detected;
  
          if (s->link == 1) {
              for (c = 1; c < sclink->channels; c++)
                  abs_sample = FFMAX(fabs(scsrc[c] * level_sc), abs_sample);
          } else {
              for (c = 1; c < sclink->channels; c++)
                  abs_sample += fabs(scsrc[c] * level_sc);
  
              abs_sample /= sclink->channels;
          }
  
          if (s->detection)
              abs_sample *= abs_sample;
  
          s->lin_slope += (abs_sample - s->lin_slope) * (abs_sample > s->lin_slope ? attack_coeff : release_coeff);
  
          if (s->mode)
              detected = s->lin_slope > s->lin_knee_start;
          else
              detected = s->lin_slope < s->lin_knee_stop;
  
          if (s->lin_slope > 0.0 && detected)
              gain = output_gain(s->lin_slope, s->ratio, s->thres,
                                 s->knee, s->knee_start, s->knee_stop,
                                 s->range, s->mode);
  
          for (c = 0; c < inlink->channels; c++)
              dst[c] = src[c] * level_in * gain * makeup;
      }
  }
  
  #if CONFIG_AGATE_FILTER
  
  #define agate_options options
  AVFILTER_DEFINE_CLASS(agate);
  
  static int query_formats(AVFilterContext *ctx)
  {
      AVFilterFormats *formats = NULL;
      AVFilterChannelLayouts *layouts;
      int ret;
  
      if ((ret = ff_add_format(&formats, AV_SAMPLE_FMT_DBL)) < 0)
          return ret;
      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();
      if (!formats)
          return AVERROR(ENOMEM);
  
      return ff_set_common_samplerates(ctx, formats);
  }
  
  static int filter_frame(AVFilterLink *inlink, AVFrame *in)
  {
      const double *src = (const double *)in->data[0];
      AVFilterContext *ctx = inlink->dst;
      AVFilterLink *outlink = ctx->outputs[0];
      AudioGateContext *s = ctx->priv;
      AVFrame *out;
      double *dst;
  
      if (av_frame_is_writable(in)) {
          out = in;
      } else {
          out = ff_get_audio_buffer(outlink, in->nb_samples);
          if (!out) {
              av_frame_free(&in);
              return AVERROR(ENOMEM);
          }
          av_frame_copy_props(out, in);
      }
      dst = (double *)out->data[0];
  
      gate(s, src, dst, src, in->nb_samples,
           s->level_in, s->level_in, inlink, inlink);
  
      if (out != in)
          av_frame_free(&in);
      return ff_filter_frame(outlink, out);
  }
  
  static const AVFilterPad inputs[] = {
      {
          .name         = "default",
          .type         = AVMEDIA_TYPE_AUDIO,
          .filter_frame = filter_frame,
          .config_props = agate_config_input,
      },
      { NULL }
  };
  
  static const AVFilterPad outputs[] = {
      {
          .name = "default",
          .type = AVMEDIA_TYPE_AUDIO,
      },
      { NULL }
  };
  
  AVFilter ff_af_agate = {
      .name           = "agate",
      .description    = NULL_IF_CONFIG_SMALL("Audio gate."),
      .query_formats  = query_formats,
      .priv_size      = sizeof(AudioGateContext),
      .priv_class     = &agate_class,
      .inputs         = inputs,
      .outputs        = outputs,
  };
  
  #endif /* CONFIG_AGATE_FILTER */
  
  #if CONFIG_SIDECHAINGATE_FILTER
  
  #define sidechaingate_options options
  AVFILTER_DEFINE_CLASS(sidechaingate);
  
  static int activate(AVFilterContext *ctx)
  {
      AudioGateContext *s = ctx->priv;
      AVFrame *out = NULL, *in[2] = { NULL };
      int ret, i, nb_samples;
      double *dst;
  
      FF_FILTER_FORWARD_STATUS_BACK_ALL(ctx->outputs[0], ctx);
      if ((ret = ff_inlink_consume_frame(ctx->inputs[0], &in[0])) > 0) {
          av_audio_fifo_write(s->fifo[0], (void **)in[0]->extended_data,
                              in[0]->nb_samples);
          av_frame_free(&in[0]);
      }
      if (ret < 0)
          return ret;
      if ((ret = ff_inlink_consume_frame(ctx->inputs[1], &in[1])) > 0) {
          av_audio_fifo_write(s->fifo[1], (void **)in[1]->extended_data,
                              in[1]->nb_samples);
          av_frame_free(&in[1]);
      }
      if (ret < 0)
          return ret;
  
      nb_samples = FFMIN(av_audio_fifo_size(s->fifo[0]), av_audio_fifo_size(s->fifo[1]));
      if (nb_samples) {
          out = ff_get_audio_buffer(ctx->outputs[0], nb_samples);
          if (!out)
              return AVERROR(ENOMEM);
          for (i = 0; i < 2; i++) {
              in[i] = ff_get_audio_buffer(ctx->inputs[i], nb_samples);
              if (!in[i]) {
                  av_frame_free(&in[0]);
                  av_frame_free(&in[1]);
                  av_frame_free(&out);
                  return AVERROR(ENOMEM);
              }
              av_audio_fifo_read(s->fifo[i], (void **)in[i]->data, nb_samples);
          }
  
          dst = (double *)out->data[0];
          out->pts = s->pts;
          s->pts += nb_samples;
  
          gate(s, (double *)in[0]->data[0], dst,
               (double *)in[1]->data[0], nb_samples,
               s->level_in, s->level_sc,
               ctx->inputs[0], ctx->inputs[1]);
  
          av_frame_free(&in[0]);
          av_frame_free(&in[1]);
  
          ret = ff_filter_frame(ctx->outputs[0], out);
          if (ret < 0)
              return ret;
      }
      FF_FILTER_FORWARD_STATUS(ctx->inputs[0], ctx->outputs[0]);
      FF_FILTER_FORWARD_STATUS(ctx->inputs[1], ctx->outputs[0]);
      if (ff_outlink_frame_wanted(ctx->outputs[0])) {
          if (!av_audio_fifo_size(s->fifo[0]))
              ff_inlink_request_frame(ctx->inputs[0]);
          if (!av_audio_fifo_size(s->fifo[1]))
              ff_inlink_request_frame(ctx->inputs[1]);
      }
      return 0;
  }
  
  static int scquery_formats(AVFilterContext *ctx)
  {
      AVFilterFormats *formats;
      AVFilterChannelLayouts *layouts = NULL;
      static const enum AVSampleFormat sample_fmts[] = {
          AV_SAMPLE_FMT_DBL,
          AV_SAMPLE_FMT_NONE
      };
      int ret, i;
  
      if (!ctx->inputs[0]->in_channel_layouts ||
          !ctx->inputs[0]->in_channel_layouts->nb_channel_layouts) {
          av_log(ctx, AV_LOG_WARNING,
                 "No channel layout for input 1\n");
              return AVERROR(EAGAIN);
      }
  
      if ((ret = ff_add_channel_layout(&layouts, ctx->inputs[0]->in_channel_layouts->channel_layouts[0])) < 0 ||
          (ret = ff_channel_layouts_ref(layouts, &ctx->outputs[0]->in_channel_layouts)) < 0)
          return ret;
  
      for (i = 0; i < 2; i++) {
          layouts = ff_all_channel_counts();
          if ((ret = ff_channel_layouts_ref(layouts, &ctx->inputs[i]->out_channel_layouts)) < 0)
              return ret;
      }
  
      formats = ff_make_format_list(sample_fmts);
      if ((ret = ff_set_common_formats(ctx, formats)) < 0)
          return ret;
  
      formats = ff_all_samplerates();
      return ff_set_common_samplerates(ctx, formats);
  }
  
  static int scconfig_output(AVFilterLink *outlink)
  {
      AVFilterContext *ctx = outlink->src;
      AudioGateContext *s = ctx->priv;
  
      if (ctx->inputs[0]->sample_rate != ctx->inputs[1]->sample_rate) {
          av_log(ctx, AV_LOG_ERROR,
                 "Inputs must have the same sample rate "
                 "%d for in0 vs %d for in1\n",
                 ctx->inputs[0]->sample_rate, ctx->inputs[1]->sample_rate);
          return AVERROR(EINVAL);
      }
  
      outlink->sample_rate = ctx->inputs[0]->sample_rate;
      outlink->time_base   = ctx->inputs[0]->time_base;
      outlink->channel_layout = ctx->inputs[0]->channel_layout;
      outlink->channels = ctx->inputs[0]->channels;
  
      s->fifo[0] = av_audio_fifo_alloc(ctx->inputs[0]->format, ctx->inputs[0]->channels, 1024);
      s->fifo[1] = av_audio_fifo_alloc(ctx->inputs[1]->format, ctx->inputs[1]->channels, 1024);
      if (!s->fifo[0] || !s->fifo[1])
          return AVERROR(ENOMEM);
  
  
      agate_config_input(ctx->inputs[0]);
  
      return 0;
  }
  
  static av_cold void uninit(AVFilterContext *ctx)
  {
      AudioGateContext *s = ctx->priv;
  
      av_audio_fifo_free(s->fifo[0]);
      av_audio_fifo_free(s->fifo[1]);
  }
  
  static const AVFilterPad sidechaingate_inputs[] = {
      {
          .name           = "main",
          .type           = AVMEDIA_TYPE_AUDIO,
      },{
          .name           = "sidechain",
          .type           = AVMEDIA_TYPE_AUDIO,
      },
      { NULL }
  };
  
  static const AVFilterPad sidechaingate_outputs[] = {
      {
          .name          = "default",
          .type          = AVMEDIA_TYPE_AUDIO,
          .config_props  = scconfig_output,
      },
      { NULL }
  };
  
  AVFilter ff_af_sidechaingate = {
      .name           = "sidechaingate",
      .description    = NULL_IF_CONFIG_SMALL("Audio sidechain gate."),
      .priv_size      = sizeof(AudioGateContext),
      .priv_class     = &sidechaingate_class,
      .query_formats  = scquery_formats,
      .activate       = activate,
      .uninit         = uninit,
      .inputs         = sidechaingate_inputs,
      .outputs        = sidechaingate_outputs,
  };
  #endif  /* CONFIG_SIDECHAINGATE_FILTER */
  