text: /*
   * Copyright (c) 2017 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/avassert.h"
  #include "libavutil/audio_fifo.h"
  #include "libavutil/channel_layout.h"
  #include "libavutil/opt.h"
  #include "libavcodec/avfft.h"
  #include "avfilter.h"
  #include "audio.h"
  #include "filters.h"
  #include "internal.h"
  #include "formats.h"
  #include "window_func.h"
  
  typedef struct AudioSurroundContext {
      const AVClass *class;
  
      char *out_channel_layout_str;
      char *in_channel_layout_str;
  
      float level_in;
      float level_out;
      float fc_in;
      float fc_out;
      float fl_in;
      float fl_out;
      float fr_in;
      float fr_out;
      float sl_in;
      float sl_out;
      float sr_in;
      float sr_out;
      float bl_in;
      float bl_out;
      float br_in;
      float br_out;
      float bc_in;
      float bc_out;
      float lfe_in;
      float lfe_out;
      int   lfe_mode;
      float angle;
      int   win_size;
      int   win_func;
      float overlap;
  
      float all_x;
      float all_y;
  
      float fc_x;
      float fl_x;
      float fr_x;
      float bl_x;
      float br_x;
      float sl_x;
      float sr_x;
      float bc_x;
  
      float fc_y;
      float fl_y;
      float fr_y;
      float bl_y;
      float br_y;
      float sl_y;
      float sr_y;
      float bc_y;
  
      float *input_levels;
      float *output_levels;
      int output_lfe;
      int lowcutf;
      int highcutf;
  
      float lowcut;
      float highcut;
  
      uint64_t out_channel_layout;
      uint64_t in_channel_layout;
      int nb_in_channels;
      int nb_out_channels;
  
      AVFrame *input;
      AVFrame *output;
      AVFrame *overlap_buffer;
  
      int buf_size;
      int hop_size;
      AVAudioFifo *fifo;
      RDFTContext **rdft, **irdft;
      float *window_func_lut;
  
      int64_t pts;
      int eof;
  
      void (*filter)(AVFilterContext *ctx);
      void (*upmix_stereo)(AVFilterContext *ctx,
                           float l_phase,
                           float r_phase,
                           float c_phase,
                           float mag_total,
                           float x, float y,
                           int n);
      void (*upmix_2_1)(AVFilterContext *ctx,
                        float l_phase,
                        float r_phase,
                        float c_phase,
                        float mag_total,
                        float lfe_im,
                        float lfe_re,
                        float x, float y,
                        int n);
      void (*upmix_3_0)(AVFilterContext *ctx,
                        float l_phase,
                        float r_phase,
                        float c_mag,
                        float c_phase,
                        float mag_total,
                        float x, float y,
                        int n);
      void (*upmix_5_0)(AVFilterContext *ctx,
                        float c_re, float c_im,
                        float mag_totall, float mag_totalr,
                        float fl_phase, float fr_phase,
                        float bl_phase, float br_phase,
                        float sl_phase, float sr_phase,
                        float xl, float yl,
                        float xr, float yr,
                        int n);
      void (*upmix_5_1)(AVFilterContext *ctx,
                        float c_re, float c_im,
                        float lfe_re, float lfe_im,
                        float mag_totall, float mag_totalr,
                        float fl_phase, float fr_phase,
                        float bl_phase, float br_phase,
                        float sl_phase, float sr_phase,
                        float xl, float yl,
                        float xr, float yr,
                        int n);
  } AudioSurroundContext;
  
  static int query_formats(AVFilterContext *ctx)
  {
      AudioSurroundContext *s = ctx->priv;
      AVFilterFormats *formats = NULL;
      AVFilterChannelLayouts *layouts = NULL;
      int ret;
  
      ret = ff_add_format(&formats, AV_SAMPLE_FMT_FLTP);
      if (ret)
          return ret;
      ret = ff_set_common_formats(ctx, formats);
      if (ret)
          return ret;
  
      layouts = NULL;
      ret = ff_add_channel_layout(&layouts, s->out_channel_layout);
      if (ret)
          return ret;
  
      ret = ff_channel_layouts_ref(layouts, &ctx->outputs[0]->incfg.channel_layouts);
      if (ret)
          return ret;
  
      layouts = NULL;
      ret = ff_add_channel_layout(&layouts, s->in_channel_layout);
      if (ret)
          return ret;
  
      ret = ff_channel_layouts_ref(layouts, &ctx->inputs[0]->outcfg.channel_layouts);
      if (ret)
          return ret;
  
      formats = ff_all_samplerates();
      if (!formats)
          return AVERROR(ENOMEM);
      return ff_set_common_samplerates(ctx, formats);
  }
  
  static int config_input(AVFilterLink *inlink)
  {
      AVFilterContext *ctx = inlink->dst;
      AudioSurroundContext *s = ctx->priv;
      int ch;
  
      s->rdft = av_calloc(inlink->channels, sizeof(*s->rdft));
      if (!s->rdft)
          return AVERROR(ENOMEM);
  
      for (ch = 0; ch < inlink->channels; ch++) {
          s->rdft[ch]  = av_rdft_init(ff_log2(s->buf_size), DFT_R2C);
          if (!s->rdft[ch])
              return AVERROR(ENOMEM);
      }
      s->nb_in_channels = inlink->channels;
      s->input_levels = av_malloc_array(s->nb_in_channels, sizeof(*s->input_levels));
      if (!s->input_levels)
          return AVERROR(ENOMEM);
      for (ch = 0;  ch < s->nb_in_channels; ch++)
          s->input_levels[ch] = s->level_in;
      ch = av_get_channel_layout_channel_index(inlink->channel_layout, AV_CH_FRONT_CENTER);
      if (ch >= 0)
          s->input_levels[ch] *= s->fc_in;
      ch = av_get_channel_layout_channel_index(inlink->channel_layout, AV_CH_FRONT_LEFT);
      if (ch >= 0)
          s->input_levels[ch] *= s->fl_in;
      ch = av_get_channel_layout_channel_index(inlink->channel_layout, AV_CH_FRONT_RIGHT);
      if (ch >= 0)
          s->input_levels[ch] *= s->fr_in;
      ch = av_get_channel_layout_channel_index(inlink->channel_layout, AV_CH_SIDE_LEFT);
      if (ch >= 0)
          s->input_levels[ch] *= s->sl_in;
      ch = av_get_channel_layout_channel_index(inlink->channel_layout, AV_CH_SIDE_RIGHT);
      if (ch >= 0)
          s->input_levels[ch] *= s->sr_in;
      ch = av_get_channel_layout_channel_index(inlink->channel_layout, AV_CH_BACK_LEFT);
      if (ch >= 0)
          s->input_levels[ch] *= s->bl_in;
      ch = av_get_channel_layout_channel_index(inlink->channel_layout, AV_CH_BACK_RIGHT);
      if (ch >= 0)
          s->input_levels[ch] *= s->br_in;
      ch = av_get_channel_layout_channel_index(inlink->channel_layout, AV_CH_BACK_CENTER);
      if (ch >= 0)
          s->input_levels[ch] *= s->bc_in;
      ch = av_get_channel_layout_channel_index(inlink->channel_layout, AV_CH_LOW_FREQUENCY);
      if (ch >= 0)
          s->input_levels[ch] *= s->lfe_in;
  
      s->input = ff_get_audio_buffer(inlink, s->buf_size * 2);
      if (!s->input)
          return AVERROR(ENOMEM);
  
      s->fifo = av_audio_fifo_alloc(inlink->format, inlink->channels, s->buf_size);
      if (!s->fifo)
          return AVERROR(ENOMEM);
  
      s->lowcut = 1.f * s->lowcutf / (inlink->sample_rate * 0.5) * (s->buf_size / 2);
      s->highcut = 1.f * s->highcutf / (inlink->sample_rate * 0.5) * (s->buf_size / 2);
  
      return 0;
  }
  
  static int config_output(AVFilterLink *outlink)
  {
      AVFilterContext *ctx = outlink->src;
      AudioSurroundContext *s = ctx->priv;
      int ch;
  
      s->irdft = av_calloc(outlink->channels, sizeof(*s->irdft));
      if (!s->irdft)
          return AVERROR(ENOMEM);
  
      for (ch = 0; ch < outlink->channels; ch++) {
          s->irdft[ch] = av_rdft_init(ff_log2(s->buf_size), IDFT_C2R);
          if (!s->irdft[ch])
              return AVERROR(ENOMEM);
      }
      s->nb_out_channels = outlink->channels;
      s->output_levels = av_malloc_array(s->nb_out_channels, sizeof(*s->output_levels));
      if (!s->output_levels)
          return AVERROR(ENOMEM);
      for (ch = 0;  ch < s->nb_out_channels; ch++)
          s->output_levels[ch] = s->level_out;
      ch = av_get_channel_layout_channel_index(outlink->channel_layout, AV_CH_FRONT_CENTER);
      if (ch >= 0)
          s->output_levels[ch] *= s->fc_out;
      ch = av_get_channel_layout_channel_index(outlink->channel_layout, AV_CH_FRONT_LEFT);
      if (ch >= 0)
          s->output_levels[ch] *= s->fl_out;
      ch = av_get_channel_layout_channel_index(outlink->channel_layout, AV_CH_FRONT_RIGHT);
      if (ch >= 0)
          s->output_levels[ch] *= s->fr_out;
      ch = av_get_channel_layout_channel_index(outlink->channel_layout, AV_CH_SIDE_LEFT);
      if (ch >= 0)
          s->output_levels[ch] *= s->sl_out;
      ch = av_get_channel_layout_channel_index(outlink->channel_layout, AV_CH_SIDE_RIGHT);
      if (ch >= 0)
          s->output_levels[ch] *= s->sr_out;
      ch = av_get_channel_layout_channel_index(outlink->channel_layout, AV_CH_BACK_LEFT);
      if (ch >= 0)
          s->output_levels[ch] *= s->bl_out;
      ch = av_get_channel_layout_channel_index(outlink->channel_layout, AV_CH_BACK_RIGHT);
      if (ch >= 0)
          s->output_levels[ch] *= s->br_out;
      ch = av_get_channel_layout_channel_index(outlink->channel_layout, AV_CH_BACK_CENTER);
      if (ch >= 0)
          s->output_levels[ch] *= s->bc_out;
      ch = av_get_channel_layout_channel_index(outlink->channel_layout, AV_CH_LOW_FREQUENCY);
      if (ch >= 0)
          s->output_levels[ch] *= s->lfe_out;
  
      s->output = ff_get_audio_buffer(outlink, s->buf_size * 2);
      s->overlap_buffer = ff_get_audio_buffer(outlink, s->buf_size * 2);
      if (!s->overlap_buffer || !s->output)
          return AVERROR(ENOMEM);
  
      return 0;
  }
  
  static void stereo_transform(float *x, float *y, float angle)
  {
      float reference, r, a;
  
      if (angle == 90.f)
          return;
  
      reference = angle * M_PI / 180.f;
      r = hypotf(*x, *y);
      a = atan2f(*x, *y);
  
      if (fabsf(a) <= M_PI_4)
          a *= reference / M_PI_2;
      else
          a = M_PI + 2 * (-2 * M_PI + reference) * (M_PI - fabsf(a)) * FFDIFFSIGN(a, 0) / (3 * M_PI);
  
      *x = av_clipf(sinf(a) * r, -1, 1);
      *y = av_clipf(cosf(a) * r, -1, 1);
  }
  
  static void stereo_position(float a, float p, float *x, float *y)
  {
      av_assert2(a >= -1.f && a <= 1.f);
      av_assert2(p >= 0.f && p <= M_PI);
      *x = av_clipf(a+a*FFMAX(0, p*p-M_PI_2), -1, 1);
      *y = av_clipf(cosf(a*M_PI_2+M_PI)*cosf(M_PI_2-p/M_PI)*M_LN10+1, -1, 1);
  }
  
  static inline void get_lfe(int output_lfe, int n, float lowcut, float highcut,
                             float *lfe_mag, float *mag_total, int lfe_mode)
  {
      if (output_lfe && n < highcut) {
          *lfe_mag    = n < lowcut ? 1.f : .5f*(1.f+cosf(M_PI*(lowcut-n)/(lowcut-highcut)));
          *lfe_mag   *= *mag_total;
          if (lfe_mode)
              *mag_total -= *lfe_mag;
      } else {
          *lfe_mag = 0.f;
      }
  }
  
  static void upmix_1_0(AVFilterContext *ctx,
                        float l_phase,
                        float r_phase,
                        float c_phase,
                        float mag_total,
                        float x, float y,
                        int n)
  {
      AudioSurroundContext *s = ctx->priv;
      float mag, *dst;
  
      dst = (float *)s->output->extended_data[0];
  
      mag = powf(1.f - fabsf(x), s->fc_x) * powf((y + 1.f) * .5f, s->fc_y) * mag_total;
  
      dst[2 * n    ] = mag * cosf(c_phase);
      dst[2 * n + 1] = mag * sinf(c_phase);
  }
  
  static void upmix_stereo(AVFilterContext *ctx,
                           float l_phase,
                           float r_phase,
                           float c_phase,
                           float mag_total,
                           float x, float y,
                           int n)
  {
      AudioSurroundContext *s = ctx->priv;
      float l_mag, r_mag, *dstl, *dstr;
  
      dstl = (float *)s->output->extended_data[0];
      dstr = (float *)s->output->extended_data[1];
  
      l_mag = powf(.5f * ( x + 1.f), s->fl_x) * powf((y + 1.f) * .5f, s->fl_y) * mag_total;
      r_mag = powf(.5f * (-x + 1.f), s->fr_x) * powf((y + 1.f) * .5f, s->fr_y) * mag_total;
  
      dstl[2 * n    ] = l_mag * cosf(l_phase);
      dstl[2 * n + 1] = l_mag * sinf(l_phase);
  
      dstr[2 * n    ] = r_mag * cosf(r_phase);
      dstr[2 * n + 1] = r_mag * sinf(r_phase);
  }
  
  static void upmix_2_1(AVFilterContext *ctx,
                        float l_phase,
                        float r_phase,
                        float c_phase,
                        float mag_total,
                        float x, float y,
                        int n)
  {
      AudioSurroundContext *s = ctx->priv;
      float lfe_mag, l_mag, r_mag, *dstl, *dstr, *dstlfe;
  
      dstl = (float *)s->output->extended_data[0];
      dstr = (float *)s->output->extended_data[1];
      dstlfe = (float *)s->output->extended_data[2];
  
      get_lfe(s->output_lfe, n, s->lowcut, s->highcut, &lfe_mag, &mag_total, s->lfe_mode);
  
      l_mag = powf(.5f * ( x + 1.f), s->fl_x) * powf((y + 1.f) * .5f, s->fl_y) * mag_total;
      r_mag = powf(.5f * (-x + 1.f), s->fr_x) * powf((y + 1.f) * .5f, s->fr_y) * mag_total;
  
      dstl[2 * n    ] = l_mag * cosf(l_phase);
      dstl[2 * n + 1] = l_mag * sinf(l_phase);
  
      dstr[2 * n    ] = r_mag * cosf(r_phase);
      dstr[2 * n + 1] = r_mag * sinf(r_phase);
  
      dstlfe[2 * n    ] = lfe_mag * cosf(c_phase);
      dstlfe[2 * n + 1] = lfe_mag * sinf(c_phase);
  }
  
  static void upmix_3_0(AVFilterContext *ctx,
                        float l_phase,
                        float r_phase,
                        float c_phase,
                        float mag_total,
                        float x, float y,
                        int n)
  {
      AudioSurroundContext *s = ctx->priv;
      float l_mag, r_mag, c_mag, *dstc, *dstl, *dstr;
  
      dstl = (float *)s->output->extended_data[0];
      dstr = (float *)s->output->extended_data[1];
      dstc = (float *)s->output->extended_data[2];
  
      c_mag = powf(1.f - fabsf(x),   s->fc_x) * powf((y + 1.f) * .5f, s->fc_y) * mag_total;
      l_mag = powf(.5f * ( x + 1.f), s->fl_x) * powf((y + 1.f) * .5f, s->fl_y) * mag_total;
      r_mag = powf(.5f * (-x + 1.f), s->fr_x) * powf((y + 1.f) * .5f, s->fr_y) * mag_total;
  
      dstl[2 * n    ] = l_mag * cosf(l_phase);
      dstl[2 * n + 1] = l_mag * sinf(l_phase);
  
      dstr[2 * n    ] = r_mag * cosf(r_phase);
      dstr[2 * n + 1] = r_mag * sinf(r_phase);
  
      dstc[2 * n    ] = c_mag * cosf(c_phase);
      dstc[2 * n + 1] = c_mag * sinf(c_phase);
  }
  
  static void upmix_3_1(AVFilterContext *ctx,
                        float l_phase,
                        float r_phase,
                        float c_phase,
                        float mag_total,
                        float x, float y,
                        int n)
  {
      AudioSurroundContext *s = ctx->priv;
      float lfe_mag, l_mag, r_mag, c_mag, *dstc, *dstl, *dstr, *dstlfe;
  
      dstl = (float *)s->output->extended_data[0];
      dstr = (float *)s->output->extended_data[1];
      dstc = (float *)s->output->extended_data[2];
      dstlfe = (float *)s->output->extended_data[3];
  
      get_lfe(s->output_lfe, n, s->lowcut, s->highcut, &lfe_mag, &mag_total, s->lfe_mode);
  
      c_mag = powf(1.f - fabsf(x),   s->fc_x) * powf((y + 1.f) * .5f, s->fc_y) * mag_total;
      l_mag = powf(.5f * ( x + 1.f), s->fl_x) * powf((y + 1.f) * .5f, s->fl_y) * mag_total;
      r_mag = powf(.5f * (-x + 1.f), s->fr_x) * powf((y + 1.f) * .5f, s->fr_y) * mag_total;
  
      dstl[2 * n    ] = l_mag * cosf(l_phase);
      dstl[2 * n + 1] = l_mag * sinf(l_phase);
  
      dstr[2 * n    ] = r_mag * cosf(r_phase);
      dstr[2 * n + 1] = r_mag * sinf(r_phase);
  
      dstc[2 * n    ] = c_mag * cosf(c_phase);
      dstc[2 * n + 1] = c_mag * sinf(c_phase);
  
      dstlfe[2 * n    ] = lfe_mag * cosf(c_phase);
      dstlfe[2 * n + 1] = lfe_mag * sinf(c_phase);
  }
  
  static void upmix_3_1_surround(AVFilterContext *ctx,
                                 float l_phase,
                                 float r_phase,
                                 float c_phase,
                                 float c_mag,
                                 float mag_total,
                                 float x, float y,
                                 int n)
  {
      AudioSurroundContext *s = ctx->priv;
      float lfe_mag, l_mag, r_mag, *dstc, *dstl, *dstr, *dstlfe;
  
      dstl = (float *)s->output->extended_data[0];
      dstr = (float *)s->output->extended_data[1];
      dstc = (float *)s->output->extended_data[2];
      dstlfe = (float *)s->output->extended_data[3];
  
      get_lfe(s->output_lfe, n, s->lowcut, s->highcut, &lfe_mag, &c_mag, s->lfe_mode);
  
      l_mag = powf(.5f * ( x + 1.f), s->fl_x) * powf((y + 1.f) * .5f, s->fl_y) * mag_total;
      r_mag = powf(.5f * (-x + 1.f), s->fr_x) * powf((y + 1.f) * .5f, s->fr_y) * mag_total;
  
      dstl[2 * n    ] = l_mag * cosf(l_phase);
      dstl[2 * n + 1] = l_mag * sinf(l_phase);
  
      dstr[2 * n    ] = r_mag * cosf(r_phase);
      dstr[2 * n + 1] = r_mag * sinf(r_phase);
  
      dstc[2 * n    ] = c_mag * cosf(c_phase);
      dstc[2 * n + 1] = c_mag * sinf(c_phase);
  
      dstlfe[2 * n    ] = lfe_mag * cosf(c_phase);
      dstlfe[2 * n + 1] = lfe_mag * sinf(c_phase);
  }
  
  static void upmix_4_0(AVFilterContext *ctx,
                        float l_phase,
                        float r_phase,
                        float c_phase,
                        float mag_total,
                        float x, float y,
                        int n)
  {
      AudioSurroundContext *s = ctx->priv;
      float b_mag, l_mag, r_mag, c_mag, *dstc, *dstl, *dstr, *dstb;
  
      dstl = (float *)s->output->extended_data[0];
      dstr = (float *)s->output->extended_data[1];
      dstc = (float *)s->output->extended_data[2];
      dstb = (float *)s->output->extended_data[3];
  
      c_mag = powf(1.f - fabsf(x),   s->fc_x) * powf((y + 1.f) * .5f, s->fc_y) * mag_total;
      b_mag = powf(1.f - fabsf(x),   s->bc_x) * powf((1.f - y) * .5f, s->bc_y) * mag_total;
      l_mag = powf(.5f * ( x + 1.f), s->fl_x) * powf((y + 1.f) * .5f, s->fl_y) * mag_total;
      r_mag = powf(.5f * (-x + 1.f), s->fr_x) * powf((y + 1.f) * .5f, s->fr_y) * mag_total;
  
      dstl[2 * n    ] = l_mag * cosf(l_phase);
      dstl[2 * n + 1] = l_mag * sinf(l_phase);
  
      dstr[2 * n    ] = r_mag * cosf(r_phase);
      dstr[2 * n + 1] = r_mag * sinf(r_phase);
  
      dstc[2 * n    ] = c_mag * cosf(c_phase);
      dstc[2 * n + 1] = c_mag * sinf(c_phase);
  
      dstb[2 * n    ] = b_mag * cosf(c_phase);
      dstb[2 * n + 1] = b_mag * sinf(c_phase);
  }
  
  static void upmix_4_1(AVFilterContext *ctx,
                        float l_phase,
                        float r_phase,
                        float c_phase,
                        float mag_total,
                        float x, float y,
                        int n)
  {
      AudioSurroundContext *s = ctx->priv;
      float lfe_mag, b_mag, l_mag, r_mag, c_mag, *dstc, *dstl, *dstr, *dstb, *dstlfe;
  
      dstl = (float *)s->output->extended_data[0];
      dstr = (float *)s->output->extended_data[1];
      dstc = (float *)s->output->extended_data[2];
      dstlfe = (float *)s->output->extended_data[3];
      dstb = (float *)s->output->extended_data[4];
  
      get_lfe(s->output_lfe, n, s->lowcut, s->highcut, &lfe_mag, &mag_total, s->lfe_mode);
  
      dstlfe[2 * n    ] = lfe_mag * cosf(c_phase);
      dstlfe[2 * n + 1] = lfe_mag * sinf(c_phase);
  
      c_mag = powf(1.f - fabsf(x),   s->fc_x) * powf((y + 1.f) * .5f, s->fc_y) * mag_total;
      b_mag = powf(1.f - fabsf(x),   s->bc_x) * powf((1.f - y) * .5f, s->bc_y) * mag_total;
      l_mag = powf(.5f * ( x + 1.f), s->fl_x) * powf((y + 1.f) * .5f, s->fl_y) * mag_total;
      r_mag = powf(.5f * (-x + 1.f), s->fr_x) * powf((y + 1.f) * .5f, s->fr_y) * mag_total;
  
      dstl[2 * n    ] = l_mag * cosf(l_phase);
      dstl[2 * n + 1] = l_mag * sinf(l_phase);
  
      dstr[2 * n    ] = r_mag * cosf(r_phase);
      dstr[2 * n + 1] = r_mag * sinf(r_phase);
  
      dstc[2 * n    ] = c_mag * cosf(c_phase);
      dstc[2 * n + 1] = c_mag * sinf(c_phase);
  
      dstb[2 * n    ] = b_mag * cosf(c_phase);
      dstb[2 * n + 1] = b_mag * sinf(c_phase);
  }
  
  static void upmix_5_0_back(AVFilterContext *ctx,
                             float l_phase,
                             float r_phase,
                             float c_phase,
                             float mag_total,
                             float x, float y,
                             int n)
  {
      AudioSurroundContext *s = ctx->priv;
      float l_mag, r_mag, ls_mag, rs_mag, c_mag, *dstc, *dstl, *dstr, *dstls, *dstrs;
  
      dstl  = (float *)s->output->extended_data[0];
      dstr  = (float *)s->output->extended_data[1];
      dstc  = (float *)s->output->extended_data[2];
      dstls = (float *)s->output->extended_data[3];
      dstrs = (float *)s->output->extended_data[4];
  
      c_mag  = powf(1.f - fabsf(x),   s->fc_x) * powf((y + 1.f) * .5f, s->fc_y) * mag_total;
      l_mag  = powf(.5f * ( x + 1.f), s->fl_x) * powf((y + 1.f) * .5f, s->fl_y) * mag_total;
      r_mag  = powf(.5f * (-x + 1.f), s->fr_x) * powf((y + 1.f) * .5f, s->fr_y) * mag_total;
      ls_mag = powf(.5f * ( x + 1.f), s->bl_x) * powf(1.f - ((y + 1.f) * .5f), s->bl_y) * mag_total;
      rs_mag = powf(.5f * (-x + 1.f), s->br_x) * powf(1.f - ((y + 1.f) * .5f), s->br_y) * mag_total;
  
      dstl[2 * n    ] = l_mag * cosf(l_phase);
      dstl[2 * n + 1] = l_mag * sinf(l_phase);
  
      dstr[2 * n    ] = r_mag * cosf(r_phase);
      dstr[2 * n + 1] = r_mag * sinf(r_phase);
  
      dstc[2 * n    ] = c_mag * cosf(c_phase);
      dstc[2 * n + 1] = c_mag * sinf(c_phase);
  
      dstls[2 * n    ] = ls_mag * cosf(l_phase);
      dstls[2 * n + 1] = ls_mag * sinf(l_phase);
  
      dstrs[2 * n    ] = rs_mag * cosf(r_phase);
      dstrs[2 * n + 1] = rs_mag * sinf(r_phase);
  }
  
  static void upmix_5_1_back(AVFilterContext *ctx,
                             float l_phase,
                             float r_phase,
                             float c_phase,
                             float mag_total,
                             float x, float y,
                             int n)
  {
      AudioSurroundContext *s = ctx->priv;
      float lfe_mag, l_mag, r_mag, ls_mag, rs_mag, c_mag, *dstc, *dstl, *dstr, *dstls, *dstrs, *dstlfe;
  
      dstl  = (float *)s->output->extended_data[0];
      dstr  = (float *)s->output->extended_data[1];
      dstc  = (float *)s->output->extended_data[2];
      dstlfe = (float *)s->output->extended_data[3];
      dstls = (float *)s->output->extended_data[4];
      dstrs = (float *)s->output->extended_data[5];
  
      get_lfe(s->output_lfe, n, s->lowcut, s->highcut, &lfe_mag, &mag_total, s->lfe_mode);
  
      c_mag  = powf(1.f - fabsf(x),   s->fc_x) * powf((y + 1.f) * .5f, s->fc_y) * mag_total;
      l_mag  = powf(.5f * ( x + 1.f), s->fl_x) * powf((y + 1.f) * .5f, s->fl_y) * mag_total;
      r_mag  = powf(.5f * (-x + 1.f), s->fr_x) * powf((y + 1.f) * .5f, s->fr_y) * mag_total;
      ls_mag = powf(.5f * ( x + 1.f), s->bl_x) * powf(1.f - ((y + 1.f) * .5f), s->bl_y) * mag_total;
      rs_mag = powf(.5f * (-x + 1.f), s->br_x) * powf(1.f - ((y + 1.f) * .5f), s->br_y) * mag_total;
  
      dstl[2 * n    ] = l_mag * cosf(l_phase);
      dstl[2 * n + 1] = l_mag * sinf(l_phase);
  
      dstr[2 * n    ] = r_mag * cosf(r_phase);
      dstr[2 * n + 1] = r_mag * sinf(r_phase);
  
      dstc[2 * n    ] = c_mag * cosf(c_phase);
      dstc[2 * n + 1] = c_mag * sinf(c_phase);
  
      dstlfe[2 * n    ] = lfe_mag * cosf(c_phase);
      dstlfe[2 * n + 1] = lfe_mag * sinf(c_phase);
  
      dstls[2 * n    ] = ls_mag * cosf(l_phase);
      dstls[2 * n + 1] = ls_mag * sinf(l_phase);
  
      dstrs[2 * n    ] = rs_mag * cosf(r_phase);
      dstrs[2 * n + 1] = rs_mag * sinf(r_phase);
  }
  
  static void upmix_6_0(AVFilterContext *ctx,
                        float l_phase,
                        float r_phase,
                        float c_phase,
                        float mag_total,
                        float x, float y,
                        int n)
  {
      AudioSurroundContext *s = ctx->priv;
      float l_mag, r_mag, ls_mag, rs_mag, c_mag, b_mag, *dstc, *dstb, *dstl, *dstr, *dstls, *dstrs;
  
      dstl  = (float *)s->output->extended_data[0];
      dstr  = (float *)s->output->extended_data[1];
      dstc  = (float *)s->output->extended_data[2];
      dstb  = (float *)s->output->extended_data[3];
      dstls = (float *)s->output->extended_data[4];
      dstrs = (float *)s->output->extended_data[5];
  
      c_mag  = powf(1.f - fabsf(x),   s->fc_x) * powf((y + 1.f) * .5f, s->fc_y) * mag_total;
      b_mag  = powf(1.f - fabsf(x),   s->bc_x) * powf((1.f - y) * .5f, s->bc_y) * mag_total;
      l_mag  = powf(.5f * ( x + 1.f), s->fl_x) * powf((y + 1.f) * .5f, s->fl_y) * mag_total;
      r_mag  = powf(.5f * (-x + 1.f), s->fr_x) * powf((y + 1.f) * .5f, s->fr_y) * mag_total;
      ls_mag = powf(.5f * ( x + 1.f), s->bl_x) * powf(1.f - ((y + 1.f) * .5f), s->bl_y) * mag_total;
      rs_mag = powf(.5f * (-x + 1.f), s->br_x) * powf(1.f - ((y + 1.f) * .5f), s->br_y) * mag_total;
  
      dstl[2 * n    ] = l_mag * cosf(l_phase);
      dstl[2 * n + 1] = l_mag * sinf(l_phase);
  
      dstr[2 * n    ] = r_mag * cosf(r_phase);
      dstr[2 * n + 1] = r_mag * sinf(r_phase);
  
      dstc[2 * n    ] = c_mag * cosf(c_phase);
      dstc[2 * n + 1] = c_mag * sinf(c_phase);
  
      dstls[2 * n    ] = ls_mag * cosf(l_phase);
      dstls[2 * n + 1] = ls_mag * sinf(l_phase);
  
      dstrs[2 * n    ] = rs_mag * cosf(r_phase);
      dstrs[2 * n + 1] = rs_mag * sinf(r_phase);
  
      dstb[2 * n    ] = b_mag * cosf(c_phase);
      dstb[2 * n + 1] = b_mag * sinf(c_phase);
  }
  
  static void upmix_6_1(AVFilterContext *ctx,
                        float l_phase,
                        float r_phase,
                        float c_phase,
                        float mag_total,
                        float x, float y,
                        int n)
  {
      AudioSurroundContext *s = ctx->priv;
      float lfe_mag, l_mag, r_mag, ls_mag, rs_mag, c_mag, b_mag, *dstc, *dstb, *dstl, *dstr, *dstls, *dstrs, *dstlfe;
  
      dstl  = (float *)s->output->extended_data[0];
      dstr  = (float *)s->output->extended_data[1];
      dstc  = (float *)s->output->extended_data[2];
      dstlfe = (float *)s->output->extended_data[3];
      dstb  = (float *)s->output->extended_data[4];
      dstls = (float *)s->output->extended_data[5];
      dstrs = (float *)s->output->extended_data[6];
  
      get_lfe(s->output_lfe, n, s->lowcut, s->highcut, &lfe_mag, &mag_total, s->lfe_mode);
  
      c_mag  = powf(1.f - fabsf(x),   s->fc_x) * powf((y + 1.f) * .5f, s->fc_y) * mag_total;
      b_mag  = powf(1.f - fabsf(x),   s->bc_x) * powf((1.f - y) * .5f, s->bc_y) * mag_total;
      l_mag  = powf(.5f * ( x + 1.f), s->fl_x) * powf((y + 1.f) * .5f, s->fl_y) * mag_total;
      r_mag  = powf(.5f * (-x + 1.f), s->fr_x) * powf((y + 1.f) * .5f, s->fr_y) * mag_total;
      ls_mag = powf(.5f * ( x + 1.f), s->bl_x) * powf(1.f - ((y + 1.f) * .5f), s->bl_y) * mag_total;
      rs_mag = powf(.5f * (-x + 1.f), s->br_x) * powf(1.f - ((y + 1.f) * .5f), s->br_y) * mag_total;
  
      dstl[2 * n    ] = l_mag * cosf(l_phase);
      dstl[2 * n + 1] = l_mag * sinf(l_phase);
  
      dstr[2 * n    ] = r_mag * cosf(r_phase);
      dstr[2 * n + 1] = r_mag * sinf(r_phase);
  
      dstc[2 * n    ] = c_mag * cosf(c_phase);
      dstc[2 * n + 1] = c_mag * sinf(c_phase);
  
      dstlfe[2 * n    ] = lfe_mag * cosf(c_phase);
      dstlfe[2 * n + 1] = lfe_mag * sinf(c_phase);
  
      dstls[2 * n    ] = ls_mag * cosf(l_phase);
      dstls[2 * n + 1] = ls_mag * sinf(l_phase);
  
      dstrs[2 * n    ] = rs_mag * cosf(r_phase);
      dstrs[2 * n + 1] = rs_mag * sinf(r_phase);
  
      dstb[2 * n    ] = b_mag * cosf(c_phase);
      dstb[2 * n + 1] = b_mag * sinf(c_phase);
  }
  
  static void upmix_5_1_back_surround(AVFilterContext *ctx,
                                      float l_phase,
                                      float r_phase,
                                      float c_phase,
                                      float c_mag,
                                      float mag_total,
                                      float x, float y,
                                      int n)
  {
      AudioSurroundContext *s = ctx->priv;
      float lfe_mag, l_mag, r_mag, *dstc, *dstl, *dstr, *dstlfe;
      float ls_mag, rs_mag, *dstls, *dstrs;
  
      dstl = (float *)s->output->extended_data[0];
      dstr = (float *)s->output->extended_data[1];
      dstc = (float *)s->output->extended_data[2];
      dstlfe = (float *)s->output->extended_data[3];
      dstls = (float *)s->output->extended_data[4];
      dstrs = (float *)s->output->extended_data[5];
  
      get_lfe(s->output_lfe, n, s->lowcut, s->highcut, &lfe_mag, &c_mag, s->lfe_mode);
  
      l_mag = powf(.5f * ( x + 1.f),  s->fl_x) * powf((y + 1.f) * .5f, s->fl_y) * mag_total;
      r_mag = powf(.5f * (-x + 1.f),  s->fr_x) * powf((y + 1.f) * .5f, s->fr_y) * mag_total;
      ls_mag = powf(.5f * ( x + 1.f), s->bl_x) * powf(1.f - ((y + 1.f) * .5f), s->bl_y) * mag_total;
      rs_mag = powf(.5f * (-x + 1.f), s->br_x) * powf(1.f - ((y + 1.f) * .5f), s->br_y) * mag_total;
  
      dstl[2 * n    ] = l_mag * cosf(l_phase);
      dstl[2 * n + 1] = l_mag * sinf(l_phase);
  
      dstr[2 * n    ] = r_mag * cosf(r_phase);
      dstr[2 * n + 1] = r_mag * sinf(r_phase);
  
      dstc[2 * n    ] = c_mag * cosf(c_phase);
      dstc[2 * n + 1] = c_mag * sinf(c_phase);
  
      dstlfe[2 * n    ] = lfe_mag * cosf(c_phase);
      dstlfe[2 * n + 1] = lfe_mag * sinf(c_phase);
  
      dstls[2 * n    ] = ls_mag * cosf(l_phase);
      dstls[2 * n + 1] = ls_mag * sinf(l_phase);
  
      dstrs[2 * n    ] = rs_mag * cosf(r_phase);
      dstrs[2 * n + 1] = rs_mag * sinf(r_phase);
  }
  
  static void upmix_5_1_back_2_1(AVFilterContext *ctx,
                                 float l_phase,
                                 float r_phase,
                                 float c_phase,
                                 float mag_total,
                                 float lfe_re,
                                 float lfe_im,
                                 float x, float y,
                                 int n)
  {
      AudioSurroundContext *s = ctx->priv;
      float c_mag, l_mag, r_mag, *dstc, *dstl, *dstr, *dstlfe;
      float ls_mag, rs_mag, *dstls, *dstrs;
  
      dstl = (float *)s->output->extended_data[0];
      dstr = (float *)s->output->extended_data[1];
      dstc = (float *)s->output->extended_data[2];
      dstlfe = (float *)s->output->extended_data[3];
      dstls = (float *)s->output->extended_data[4];
      dstrs = (float *)s->output->extended_data[5];
  
      c_mag  = powf(1.f - fabsf(x),   s->fc_x) * powf((y + 1.f) * .5f, s->fc_y) * mag_total;
      l_mag  = powf(.5f * ( x + 1.f), s->fl_x) * powf((y + 1.f) * .5f, s->fl_y) * mag_total;
      r_mag  = powf(.5f * (-x + 1.f), s->fr_x) * powf((y + 1.f) * .5f, s->fr_y) * mag_total;
      ls_mag = powf(.5f * ( x + 1.f), s->bl_x) * powf(1.f - ((y + 1.f) * .5f), s->bl_y) * mag_total;
      rs_mag = powf(.5f * (-x + 1.f), s->br_x) * powf(1.f - ((y + 1.f) * .5f), s->br_y) * mag_total;
  
      dstl[2 * n    ] = l_mag * cosf(l_phase);
      dstl[2 * n + 1] = l_mag * sinf(l_phase);
  
      dstr[2 * n    ] = r_mag * cosf(r_phase);
      dstr[2 * n + 1] = r_mag * sinf(r_phase);
  
      dstc[2 * n    ] = c_mag * cosf(c_phase);
      dstc[2 * n + 1] = c_mag * sinf(c_phase);
  
      dstlfe[2 * n    ] = lfe_re;
      dstlfe[2 * n + 1] = lfe_im;
  
      dstls[2 * n    ] = ls_mag * cosf(l_phase);
      dstls[2 * n + 1] = ls_mag * sinf(l_phase);
  
      dstrs[2 * n    ] = rs_mag * cosf(r_phase);
      dstrs[2 * n + 1] = rs_mag * sinf(r_phase);
  }
  
  static void upmix_7_0(AVFilterContext *ctx,
                        float l_phase,
                        float r_phase,
                        float c_phase,
                        float mag_total,
                        float x, float y,
                        int n)
  {
      float l_mag, r_mag, ls_mag, rs_mag, c_mag, lb_mag, rb_mag;
      float *dstc, *dstl, *dstr, *dstls, *dstrs, *dstlb, *dstrb;
      AudioSurroundContext *s = ctx->priv;
  
      dstl  = (float *)s->output->extended_data[0];
      dstr  = (float *)s->output->extended_data[1];
      dstc  = (float *)s->output->extended_data[2];
      dstlb = (float *)s->output->extended_data[3];
      dstrb = (float *)s->output->extended_data[4];
      dstls = (float *)s->output->extended_data[5];
      dstrs = (float *)s->output->extended_data[6];
  
      c_mag  = powf(1.f - fabsf(x),   s->fc_x) * powf((y + 1.f) * .5f, s->fc_y) * mag_total;
      l_mag  = powf(.5f * ( x + 1.f), s->fl_x) * powf((y + 1.f) * .5f, s->fl_y) * mag_total;
      r_mag  = powf(.5f * (-x + 1.f), s->fr_x) * powf((y + 1.f) * .5f, s->fr_y) * mag_total;
      lb_mag = powf(.5f * ( x + 1.f), s->bl_x) * powf(1.f - ((y + 1.f) * .5f), s->bl_y) * mag_total;
      rb_mag = powf(.5f * (-x + 1.f), s->br_x) * powf(1.f - ((y + 1.f) * .5f), s->br_y) * mag_total;
      ls_mag = powf(.5f * ( x + 1.f), s->sl_x) * powf(1.f - fabsf(y), s->sl_y) * mag_total;
      rs_mag = powf(.5f * (-x + 1.f), s->sr_x) * powf(1.f - fabsf(y), s->sr_y) * mag_total;
  
      dstl[2 * n    ] = l_mag * cosf(l_phase);
      dstl[2 * n + 1] = l_mag * sinf(l_phase);
  
      dstr[2 * n    ] = r_mag * cosf(r_phase);
      dstr[2 * n + 1] = r_mag * sinf(r_phase);
  
      dstc[2 * n    ] = c_mag * cosf(c_phase);
      dstc[2 * n + 1] = c_mag * sinf(c_phase);
  
      dstlb[2 * n    ] = lb_mag * cosf(l_phase);
      dstlb[2 * n + 1] = lb_mag * sinf(l_phase);
  
      dstrb[2 * n    ] = rb_mag * cosf(r_phase);
      dstrb[2 * n + 1] = rb_mag * sinf(r_phase);
  
      dstls[2 * n    ] = ls_mag * cosf(l_phase);
      dstls[2 * n + 1] = ls_mag * sinf(l_phase);
  
      dstrs[2 * n    ] = rs_mag * cosf(r_phase);
      dstrs[2 * n + 1] = rs_mag * sinf(r_phase);
  }
  
  static void upmix_7_1(AVFilterContext *ctx,
                        float l_phase,
                        float r_phase,
                        float c_phase,
                        float mag_total,
                        float x, float y,
                        int n)
  {
      float lfe_mag, l_mag, r_mag, ls_mag, rs_mag, c_mag, lb_mag, rb_mag;
      float *dstc, *dstl, *dstr, *dstls, *dstrs, *dstlb, *dstrb, *dstlfe;
      AudioSurroundContext *s = ctx->priv;
  
      dstl  = (float *)s->output->extended_data[0];
      dstr  = (float *)s->output->extended_data[1];
      dstc  = (float *)s->output->extended_data[2];
      dstlfe = (float *)s->output->extended_data[3];
      dstlb = (float *)s->output->extended_data[4];
      dstrb = (float *)s->output->extended_data[5];
      dstls = (float *)s->output->extended_data[6];
      dstrs = (float *)s->output->extended_data[7];
  
      get_lfe(s->output_lfe, n, s->lowcut, s->highcut, &lfe_mag, &mag_total, s->lfe_mode);
  
      c_mag  = powf(1.f - fabsf(x), s->fc_x)   * powf((y + 1.f) * .5f, s->fc_y) * mag_total;
      l_mag  = powf(.5f * ( x + 1.f), s->fl_x) * powf((y + 1.f) * .5f, s->fl_y) * mag_total;
      r_mag  = powf(.5f * (-x + 1.f), s->fr_x) * powf((y + 1.f) * .5f, s->fr_y) * mag_total;
      lb_mag = powf(.5f * ( x + 1.f), s->bl_x) * powf(1.f - ((y + 1.f) * .5f), s->bl_y) * mag_total;
      rb_mag = powf(.5f * (-x + 1.f), s->br_x) * powf(1.f - ((y + 1.f) * .5f), s->br_y) * mag_total;
      ls_mag = powf(.5f * ( x + 1.f), s->sl_x) * powf(1.f - fabsf(y), s->sl_y) * mag_total;
      rs_mag = powf(.5f * (-x + 1.f), s->sr_x) * powf(1.f - fabsf(y), s->sr_y) * mag_total;
  
      dstl[2 * n    ] = l_mag * cosf(l_phase);
      dstl[2 * n + 1] = l_mag * sinf(l_phase);
  
      dstr[2 * n    ] = r_mag * cosf(r_phase);
      dstr[2 * n + 1] = r_mag * sinf(r_phase);
  
      dstc[2 * n    ] = c_mag * cosf(c_phase);
      dstc[2 * n + 1] = c_mag * sinf(c_phase);
  
      dstlfe[2 * n    ] = lfe_mag * cosf(c_phase);
      dstlfe[2 * n + 1] = lfe_mag * sinf(c_phase);
  
      dstlb[2 * n    ] = lb_mag * cosf(l_phase);
      dstlb[2 * n + 1] = lb_mag * sinf(l_phase);
  
      dstrb[2 * n    ] = rb_mag * cosf(r_phase);
      dstrb[2 * n + 1] = rb_mag * sinf(r_phase);
  
      dstls[2 * n    ] = ls_mag * cosf(l_phase);
      dstls[2 * n + 1] = ls_mag * sinf(l_phase);
  
      dstrs[2 * n    ] = rs_mag * cosf(r_phase);
      dstrs[2 * n + 1] = rs_mag * sinf(r_phase);
  }
  
  static void upmix_7_1_5_0_side(AVFilterContext *ctx,
                                 float c_re, float c_im,
                                 float mag_totall, float mag_totalr,
                                 float fl_phase, float fr_phase,
                                 float bl_phase, float br_phase,
                                 float sl_phase, float sr_phase,
                                 float xl, float yl,
                                 float xr, float yr,
                                 int n)
  {
      float fl_mag, fr_mag, ls_mag, rs_mag, lb_mag, rb_mag;
      float *dstc, *dstl, *dstr, *dstls, *dstrs, *dstlb, *dstrb, *dstlfe;
      float lfe_mag, c_phase, mag_total = (mag_totall + mag_totalr) * 0.5;
      AudioSurroundContext *s = ctx->priv;
  
      dstl  = (float *)s->output->extended_data[0];
      dstr  = (float *)s->output->extended_data[1];
      dstc  = (float *)s->output->extended_data[2];
      dstlfe = (float *)s->output->extended_data[3];
      dstlb = (float *)s->output->extended_data[4];
      dstrb = (float *)s->output->extended_data[5];
      dstls = (float *)s->output->extended_data[6];
      dstrs = (float *)s->output->extended_data[7];
  
      c_phase = atan2f(c_im, c_re);
  
      get_lfe(s->output_lfe, n, s->lowcut, s->highcut, &lfe_mag, &mag_total, s->lfe_mode);
  
      fl_mag = powf(.5f * (xl + 1.f), s->fl_x) * powf((yl + 1.f) * .5f, s->fl_y) * mag_totall;
      fr_mag = powf(.5f * (xr + 1.f), s->fr_x) * powf((yr + 1.f) * .5f, s->fr_y) * mag_totalr;
      lb_mag = powf(.5f * (-xl + 1.f), s->bl_x) * powf((yl + 1.f) * .5f, s->bl_y) * mag_totall;
      rb_mag = powf(.5f * (-xr + 1.f), s->br_x) * powf((yr + 1.f) * .5f, s->br_y) * mag_totalr;
      ls_mag = powf(1.f - fabsf(xl), s->sl_x) * powf((yl + 1.f) * .5f, s->sl_y) * mag_totall;
      rs_mag = powf(1.f - fabsf(xr), s->sr_x) * powf((yr + 1.f) * .5f, s->sr_y) * mag_totalr;
  
      dstl[2 * n    ] = fl_mag * cosf(fl_phase);
      dstl[2 * n + 1] = fl_mag * sinf(fl_phase);
  
      dstr[2 * n    ] = fr_mag * cosf(fr_phase);
      dstr[2 * n + 1] = fr_mag * sinf(fr_phase);
  
      dstc[2 * n    ] = c_re;
      dstc[2 * n + 1] = c_im;
  
      dstlfe[2 * n    ] = lfe_mag * cosf(c_phase);
      dstlfe[2 * n + 1] = lfe_mag * sinf(c_phase);
  
      dstlb[2 * n    ] = lb_mag * cosf(bl_phase);
      dstlb[2 * n + 1] = lb_mag * sinf(bl_phase);
  
      dstrb[2 * n    ] = rb_mag * cosf(br_phase);
      dstrb[2 * n + 1] = rb_mag * sinf(br_phase);
  
      dstls[2 * n    ] = ls_mag * cosf(sl_phase);
      dstls[2 * n + 1] = ls_mag * sinf(sl_phase);
  
      dstrs[2 * n    ] = rs_mag * cosf(sr_phase);
      dstrs[2 * n + 1] = rs_mag * sinf(sr_phase);
  }
  
  static void upmix_7_1_5_1(AVFilterContext *ctx,
                            float c_re, float c_im,
                            float lfe_re, float lfe_im,
                            float mag_totall, float mag_totalr,
                            float fl_phase, float fr_phase,
                            float bl_phase, float br_phase,
                            float sl_phase, float sr_phase,
                            float xl, float yl,
                            float xr, float yr,
                            int n)
  {
      float fl_mag, fr_mag, ls_mag, rs_mag, lb_mag, rb_mag;
      float *dstc, *dstl, *dstr, *dstls, *dstrs, *dstlb, *dstrb, *dstlfe;
      AudioSurroundContext *s = ctx->priv;
  
      dstl  = (float *)s->output->extended_data[0];
      dstr  = (float *)s->output->extended_data[1];
      dstc  = (float *)s->output->extended_data[2];
      dstlfe = (float *)s->output->extended_data[3];
      dstlb = (float *)s->output->extended_data[4];
      dstrb = (float *)s->output->extended_data[5];
      dstls = (float *)s->output->extended_data[6];
      dstrs = (float *)s->output->extended_data[7];
  
      fl_mag = powf(.5f * (xl + 1.f), s->fl_x) * powf((yl + 1.f) * .5f, s->fl_y) * mag_totall;
      fr_mag = powf(.5f * (xr + 1.f), s->fr_x) * powf((yr + 1.f) * .5f, s->fr_y) * mag_totalr;
      lb_mag = powf(.5f * (-xl + 1.f), s->bl_x) * powf((yl + 1.f) * .5f, s->bl_y) * mag_totall;
      rb_mag = powf(.5f * (-xr + 1.f), s->br_x) * powf((yr + 1.f) * .5f, s->br_y) * mag_totalr;
      ls_mag = powf(1.f - fabsf(xl), s->sl_x) * powf((yl + 1.f) * .5f, s->sl_y) * mag_totall;
      rs_mag = powf(1.f - fabsf(xr), s->sr_x) * powf((yr + 1.f) * .5f, s->sr_y) * mag_totalr;
  
      dstl[2 * n    ] = fl_mag * cosf(fl_phase);
      dstl[2 * n + 1] = fl_mag * sinf(fl_phase);
  
      dstr[2 * n    ] = fr_mag * cosf(fr_phase);
      dstr[2 * n + 1] = fr_mag * sinf(fr_phase);
  
      dstc[2 * n    ] = c_re;
      dstc[2 * n + 1] = c_im;
  
      dstlfe[2 * n    ] = lfe_re;
      dstlfe[2 * n + 1] = lfe_im;
  
      dstlb[2 * n    ] = lb_mag * cosf(bl_phase);
      dstlb[2 * n + 1] = lb_mag * sinf(bl_phase);
  
      dstrb[2 * n    ] = rb_mag * cosf(br_phase);
      dstrb[2 * n + 1] = rb_mag * sinf(br_phase);
  
      dstls[2 * n    ] = ls_mag * cosf(sl_phase);
      dstls[2 * n + 1] = ls_mag * sinf(sl_phase);
  
      dstrs[2 * n    ] = rs_mag * cosf(sr_phase);
      dstrs[2 * n + 1] = rs_mag * sinf(sr_phase);
  }
  
  static void filter_stereo(AVFilterContext *ctx)
  {
      AudioSurroundContext *s = ctx->priv;
      float *srcl, *srcr;
      int n;
  
      srcl = (float *)s->input->extended_data[0];
      srcr = (float *)s->input->extended_data[1];
  
      for (n = 0; n < s->buf_size; n++) {
          float l_re = srcl[2 * n], r_re = srcr[2 * n];
          float l_im = srcl[2 * n + 1], r_im = srcr[2 * n + 1];
          float c_phase = atan2f(l_im + r_im, l_re + r_re);
          float l_mag = hypotf(l_re, l_im);
          float r_mag = hypotf(r_re, r_im);
          float l_phase = atan2f(l_im, l_re);
          float r_phase = atan2f(r_im, r_re);
          float phase_dif = fabsf(l_phase - r_phase);
          float mag_sum = l_mag + r_mag;
          float mag_dif = mag_sum < 0.000001 ? FFDIFFSIGN(l_mag, r_mag) : (l_mag - r_mag) / mag_sum;
          float mag_total = hypotf(l_mag, r_mag);
          float x, y;
  
          if (phase_dif > M_PI)
              phase_dif = 2 * M_PI - phase_dif;
  
          stereo_position(mag_dif, phase_dif, &x, &y);
          stereo_transform(&x, &y, s->angle);
  
          s->upmix_stereo(ctx, l_phase, r_phase, c_phase, mag_total, x, y, n);
      }
  }
  
  static void filter_surround(AVFilterContext *ctx)
  {
      AudioSurroundContext *s = ctx->priv;
      float *srcl, *srcr, *srcc;
      int n;
  
      srcl = (float *)s->input->extended_data[0];
      srcr = (float *)s->input->extended_data[1];
      srcc = (float *)s->input->extended_data[2];
  
      for (n = 0; n < s->buf_size; n++) {
          float l_re = srcl[2 * n], r_re = srcr[2 * n];
          float l_im = srcl[2 * n + 1], r_im = srcr[2 * n + 1];
          float c_re = srcc[2 * n], c_im = srcc[2 * n + 1];
          float c_mag = hypotf(c_re, c_im);
          float c_phase = atan2f(c_im, c_re);
          float l_mag = hypotf(l_re, l_im);
          float r_mag = hypotf(r_re, r_im);
          float l_phase = atan2f(l_im, l_re);
          float r_phase = atan2f(r_im, r_re);
          float phase_dif = fabsf(l_phase - r_phase);
          float mag_sum = l_mag + r_mag;
          float mag_dif = mag_sum < 0.000001 ? FFDIFFSIGN(l_mag, r_mag) : (l_mag - r_mag) / mag_sum;
          float mag_total = hypotf(l_mag, r_mag);
          float x, y;
  
          if (phase_dif > M_PI)
              phase_dif = 2 * M_PI - phase_dif;
  
          stereo_position(mag_dif, phase_dif, &x, &y);
          stereo_transform(&x, &y, s->angle);
  
          s->upmix_3_0(ctx, l_phase, r_phase, c_phase, c_mag, mag_total, x, y, n);
      }
  }
  
  static void filter_2_1(AVFilterContext *ctx)
  {
      AudioSurroundContext *s = ctx->priv;
      float *srcl, *srcr, *srclfe;
      int n;
  
      srcl = (float *)s->input->extended_data[0];
      srcr = (float *)s->input->extended_data[1];
      srclfe = (float *)s->input->extended_data[2];
  
      for (n = 0; n < s->buf_size; n++) {
          float l_re = srcl[2 * n], r_re = srcr[2 * n];
          float l_im = srcl[2 * n + 1], r_im = srcr[2 * n + 1];
          float lfe_re = srclfe[2 * n], lfe_im = srclfe[2 * n + 1];
          float c_phase = atan2f(l_im + r_im, l_re + r_re);
          float l_mag = hypotf(l_re, l_im);
          float r_mag = hypotf(r_re, r_im);
          float l_phase = atan2f(l_im, l_re);
          float r_phase = atan2f(r_im, r_re);
          float phase_dif = fabsf(l_phase - r_phase);
          float mag_sum = l_mag + r_mag;
          float mag_dif = mag_sum < 0.000001 ? FFDIFFSIGN(l_mag, r_mag) : (l_mag - r_mag) / mag_sum;
          float mag_total = hypotf(l_mag, r_mag);
          float x, y;
  
          if (phase_dif > M_PI)
              phase_dif = 2 * M_PI - phase_dif;
  
          stereo_position(mag_dif, phase_dif, &x, &y);
          stereo_transform(&x, &y, s->angle);
  
          s->upmix_2_1(ctx, l_phase, r_phase, c_phase, mag_total, lfe_re, lfe_im, x, y, n);
      }
  }
  
  static void filter_5_0_side(AVFilterContext *ctx)
  {
      AudioSurroundContext *s = ctx->priv;
      float *srcl, *srcr, *srcc, *srcsl, *srcsr;
      int n;
  
      srcl = (float *)s->input->extended_data[0];
      srcr = (float *)s->input->extended_data[1];
      srcc = (float *)s->input->extended_data[2];
      srcsl = (float *)s->input->extended_data[3];
      srcsr = (float *)s->input->extended_data[4];
  
      for (n = 0; n < s->buf_size; n++) {
          float fl_re = srcl[2 * n], fr_re = srcr[2 * n];
          float fl_im = srcl[2 * n + 1], fr_im = srcr[2 * n + 1];
          float c_re = srcc[2 * n], c_im = srcc[2 * n + 1];
          float sl_re = srcsl[2 * n], sl_im = srcsl[2 * n + 1];
          float sr_re = srcsr[2 * n], sr_im = srcsr[2 * n + 1];
          float fl_mag = hypotf(fl_re, fl_im);
          float fr_mag = hypotf(fr_re, fr_im);
          float fl_phase = atan2f(fl_im, fl_re);
          float fr_phase = atan2f(fr_im, fr_re);
          float sl_mag = hypotf(sl_re, sl_im);
          float sr_mag = hypotf(sr_re, sr_im);
          float sl_phase = atan2f(sl_im, sl_re);
          float sr_phase = atan2f(sr_im, sr_re);
          float phase_difl = fabsf(fl_phase - sl_phase);
          float phase_difr = fabsf(fr_phase - sr_phase);
          float magl_sum = fl_mag + sl_mag;
          float magr_sum = fr_mag + sr_mag;
          float mag_difl = magl_sum < 0.000001 ? FFDIFFSIGN(fl_mag, sl_mag) : (fl_mag - sl_mag) / magl_sum;
          float mag_difr = magr_sum < 0.000001 ? FFDIFFSIGN(fr_mag, sr_mag) : (fr_mag - sr_mag) / magr_sum;
          float mag_totall = hypotf(fl_mag, sl_mag);
          float mag_totalr = hypotf(fr_mag, sr_mag);
          float bl_phase = atan2f(fl_im + sl_im, fl_re + sl_re);
          float br_phase = atan2f(fr_im + sr_im, fr_re + sr_re);
          float xl, yl;
          float xr, yr;
  
          if (phase_difl > M_PI)
              phase_difl = 2 * M_PI - phase_difl;
  
          if (phase_difr > M_PI)
              phase_difr = 2 * M_PI - phase_difr;
  
          stereo_position(mag_difl, phase_difl, &xl, &yl);
          stereo_position(mag_difr, phase_difr, &xr, &yr);
  
          s->upmix_5_0(ctx, c_re, c_im,
                       mag_totall, mag_totalr,
                       fl_phase, fr_phase,
                       bl_phase, br_phase,
                       sl_phase, sr_phase,
                       xl, yl, xr, yr, n);
      }
  }
  
  static void filter_5_1_side(AVFilterContext *ctx)
  {
      AudioSurroundContext *s = ctx->priv;
      float *srcl, *srcr, *srcc, *srclfe, *srcsl, *srcsr;
      int n;
  
      srcl = (float *)s->input->extended_data[0];
      srcr = (float *)s->input->extended_data[1];
      srcc = (float *)s->input->extended_data[2];
      srclfe = (float *)s->input->extended_data[3];
      srcsl = (float *)s->input->extended_data[4];
      srcsr = (float *)s->input->extended_data[5];
  
      for (n = 0; n < s->buf_size; n++) {
          float fl_re = srcl[2 * n], fr_re = srcr[2 * n];
          float fl_im = srcl[2 * n + 1], fr_im = srcr[2 * n + 1];
          float c_re = srcc[2 * n], c_im = srcc[2 * n + 1];
          float lfe_re = srclfe[2 * n], lfe_im = srclfe[2 * n + 1];
          float sl_re = srcsl[2 * n], sl_im = srcsl[2 * n + 1];
          float sr_re = srcsr[2 * n], sr_im = srcsr[2 * n + 1];
          float fl_mag = hypotf(fl_re, fl_im);
          float fr_mag = hypotf(fr_re, fr_im);
          float fl_phase = atan2f(fl_im, fl_re);
          float fr_phase = atan2f(fr_im, fr_re);
          float sl_mag = hypotf(sl_re, sl_im);
          float sr_mag = hypotf(sr_re, sr_im);
          float sl_phase = atan2f(sl_im, sl_re);
          float sr_phase = atan2f(sr_im, sr_re);
          float phase_difl = fabsf(fl_phase - sl_phase);
          float phase_difr = fabsf(fr_phase - sr_phase);
          float magl_sum = fl_mag + sl_mag;
          float magr_sum = fr_mag + sr_mag;
          float mag_difl = magl_sum < 0.000001 ? FFDIFFSIGN(fl_mag, sl_mag) : (fl_mag - sl_mag) / magl_sum;
          float mag_difr = magr_sum < 0.000001 ? FFDIFFSIGN(fr_mag, sr_mag) : (fr_mag - sr_mag) / magr_sum;
          float mag_totall = hypotf(fl_mag, sl_mag);
          float mag_totalr = hypotf(fr_mag, sr_mag);
          float bl_phase = atan2f(fl_im + sl_im, fl_re + sl_re);
          float br_phase = atan2f(fr_im + sr_im, fr_re + sr_re);
          float xl, yl;
          float xr, yr;
  
          if (phase_difl > M_PI)
              phase_difl = 2 * M_PI - phase_difl;
  
          if (phase_difr > M_PI)
              phase_difr = 2 * M_PI - phase_difr;
  
          stereo_position(mag_difl, phase_difl, &xl, &yl);
          stereo_position(mag_difr, phase_difr, &xr, &yr);
  
          s->upmix_5_1(ctx, c_re, c_im, lfe_re, lfe_im,
                       mag_totall, mag_totalr,
                       fl_phase, fr_phase,
                       bl_phase, br_phase,
                       sl_phase, sr_phase,
                       xl, yl, xr, yr, n);
      }
  }
  
  static void filter_5_1_back(AVFilterContext *ctx)
  {
      AudioSurroundContext *s = ctx->priv;
      float *srcl, *srcr, *srcc, *srclfe, *srcbl, *srcbr;
      int n;
  
      srcl = (float *)s->input->extended_data[0];
      srcr = (float *)s->input->extended_data[1];
      srcc = (float *)s->input->extended_data[2];
      srclfe = (float *)s->input->extended_data[3];
      srcbl = (float *)s->input->extended_data[4];
      srcbr = (float *)s->input->extended_data[5];
  
      for (n = 0; n < s->buf_size; n++) {
          float fl_re = srcl[2 * n], fr_re = srcr[2 * n];
          float fl_im = srcl[2 * n + 1], fr_im = srcr[2 * n + 1];
          float c_re = srcc[2 * n], c_im = srcc[2 * n + 1];
          float lfe_re = srclfe[2 * n], lfe_im = srclfe[2 * n + 1];
          float bl_re = srcbl[2 * n], bl_im = srcbl[2 * n + 1];
          float br_re = srcbr[2 * n], br_im = srcbr[2 * n + 1];
          float fl_mag = hypotf(fl_re, fl_im);
          float fr_mag = hypotf(fr_re, fr_im);
          float fl_phase = atan2f(fl_im, fl_re);
          float fr_phase = atan2f(fr_im, fr_re);
          float bl_mag = hypotf(bl_re, bl_im);
          float br_mag = hypotf(br_re, br_im);
          float bl_phase = atan2f(bl_im, bl_re);
          float br_phase = atan2f(br_im, br_re);
          float phase_difl = fabsf(fl_phase - bl_phase);
          float phase_difr = fabsf(fr_phase - br_phase);
          float magl_sum = fl_mag + bl_mag;
          float magr_sum = fr_mag + br_mag;
          float mag_difl = magl_sum < 0.000001 ? FFDIFFSIGN(fl_mag, bl_mag) : (fl_mag - bl_mag) / magl_sum;
          float mag_difr = magr_sum < 0.000001 ? FFDIFFSIGN(fr_mag, br_mag) : (fr_mag - br_mag) / magr_sum;
          float mag_totall = hypotf(fl_mag, bl_mag);
          float mag_totalr = hypotf(fr_mag, br_mag);
          float sl_phase = atan2f(fl_im + bl_im, fl_re + bl_re);
          float sr_phase = atan2f(fr_im + br_im, fr_re + br_re);
          float xl, yl;
          float xr, yr;
  
          if (phase_difl > M_PI)
              phase_difl = 2 * M_PI - phase_difl;
  
          if (phase_difr > M_PI)
              phase_difr = 2 * M_PI - phase_difr;
  
          stereo_position(mag_difl, phase_difl, &xl, &yl);
          stereo_position(mag_difr, phase_difr, &xr, &yr);
  
          s->upmix_5_1(ctx, c_re, c_im, lfe_re, lfe_im,
                       mag_totall, mag_totalr,
                       fl_phase, fr_phase,
                       bl_phase, br_phase,
                       sl_phase, sr_phase,
                       xl, yl, xr, yr, n);
      }
  }
  
  static av_cold int init(AVFilterContext *ctx)
  {
      AudioSurroundContext *s = ctx->priv;
      float overlap;
      int i;
  
      if (!(s->out_channel_layout = av_get_channel_layout(s->out_channel_layout_str))) {
          av_log(ctx, AV_LOG_ERROR, "Error parsing output channel layout '%s'.\n",
                 s->out_channel_layout_str);
          return AVERROR(EINVAL);
      }
  
      if (!(s->in_channel_layout = av_get_channel_layout(s->in_channel_layout_str))) {
          av_log(ctx, AV_LOG_ERROR, "Error parsing input channel layout '%s'.\n",
                 s->in_channel_layout_str);
          return AVERROR(EINVAL);
      }
  
      if (s->lowcutf >= s->highcutf) {
          av_log(ctx, AV_LOG_ERROR, "Low cut-off '%d' should be less than high cut-off '%d'.\n",
                 s->lowcutf, s->highcutf);
          return AVERROR(EINVAL);
      }
  
      switch (s->in_channel_layout) {
      case AV_CH_LAYOUT_STEREO:
          s->filter = filter_stereo;
          switch (s->out_channel_layout) {
          case AV_CH_LAYOUT_MONO:
              s->upmix_stereo = upmix_1_0;
              break;
          case AV_CH_LAYOUT_STEREO:
              s->upmix_stereo = upmix_stereo;
              break;
          case AV_CH_LAYOUT_2POINT1:
              s->upmix_stereo = upmix_2_1;
              break;
          case AV_CH_LAYOUT_SURROUND:
              s->upmix_stereo = upmix_3_0;
              break;
          case AV_CH_LAYOUT_3POINT1:
              s->upmix_stereo = upmix_3_1;
              break;
          case AV_CH_LAYOUT_4POINT0:
              s->upmix_stereo = upmix_4_0;
              break;
          case AV_CH_LAYOUT_4POINT1:
              s->upmix_stereo = upmix_4_1;
              break;
          case AV_CH_LAYOUT_5POINT0_BACK:
              s->upmix_stereo = upmix_5_0_back;
              break;
          case AV_CH_LAYOUT_5POINT1_BACK:
              s->upmix_stereo = upmix_5_1_back;
              break;
          case AV_CH_LAYOUT_6POINT0:
              s->upmix_stereo = upmix_6_0;
              break;
          case AV_CH_LAYOUT_6POINT1:
              s->upmix_stereo = upmix_6_1;
              break;
          case AV_CH_LAYOUT_7POINT0:
              s->upmix_stereo = upmix_7_0;
              break;
          case AV_CH_LAYOUT_7POINT1:
              s->upmix_stereo = upmix_7_1;
              break;
          default:
              goto fail;
          }
          break;
      case AV_CH_LAYOUT_2POINT1:
          s->filter = filter_2_1;
          switch (s->out_channel_layout) {
          case AV_CH_LAYOUT_5POINT1_BACK:
              s->upmix_2_1 = upmix_5_1_back_2_1;
              break;
          default:
              goto fail;
          }
          break;
      case AV_CH_LAYOUT_SURROUND:
          s->filter = filter_surround;
          switch (s->out_channel_layout) {
          case AV_CH_LAYOUT_3POINT1:
              s->upmix_3_0 = upmix_3_1_surround;
              break;
          case AV_CH_LAYOUT_5POINT1_BACK:
              s->upmix_3_0 = upmix_5_1_back_surround;
              break;
          default:
              goto fail;
          }
          break;
      case AV_CH_LAYOUT_5POINT0:
          s->filter = filter_5_0_side;
          switch (s->out_channel_layout) {
          case AV_CH_LAYOUT_7POINT1:
              s->upmix_5_0 = upmix_7_1_5_0_side;
              break;
          default:
              goto fail;
          }
          break;
      case AV_CH_LAYOUT_5POINT1:
          s->filter = filter_5_1_side;
          switch (s->out_channel_layout) {
          case AV_CH_LAYOUT_7POINT1:
              s->upmix_5_1 = upmix_7_1_5_1;
              break;
          default:
              goto fail;
          }
          break;
      case AV_CH_LAYOUT_5POINT1_BACK:
          s->filter = filter_5_1_back;
          switch (s->out_channel_layout) {
          case AV_CH_LAYOUT_7POINT1:
              s->upmix_5_1 = upmix_7_1_5_1;
              break;
          default:
              goto fail;
          }
          break;
      default:
  fail:
          av_log(ctx, AV_LOG_ERROR, "Unsupported upmix: '%s' -> '%s'.\n",
                 s->in_channel_layout_str, s->out_channel_layout_str);
          return AVERROR(EINVAL);
      }
  
      s->buf_size = 1 << av_log2(s->win_size);
      s->pts = AV_NOPTS_VALUE;
  
      s->window_func_lut = av_calloc(s->buf_size, sizeof(*s->window_func_lut));
      if (!s->window_func_lut)
          return AVERROR(ENOMEM);
  
      generate_window_func(s->window_func_lut, s->buf_size, s->win_func, &overlap);
      if (s->overlap == 1)
          s->overlap = overlap;
  
      for (i = 0; i < s->buf_size; i++)
          s->window_func_lut[i] = sqrtf(s->window_func_lut[i] / s->buf_size);
      s->hop_size = s->buf_size * (1. - s->overlap);
      if (s->hop_size <= 0)
          return AVERROR(EINVAL);
  
      if (s->all_x >= 0.f)
          s->fc_x = s->fl_x = s->fr_x = s->bc_x = s->sl_x = s->sr_x = s->bl_x = s->br_x = s->all_x;
      if (s->all_y >= 0.f)
          s->fc_y = s->fl_y = s->fr_y = s->bc_y = s->sl_y = s->sr_y = s->bl_y = s->br_y = s->all_y;
  
      return 0;
  }
  
  static int fft_channel(AVFilterContext *ctx, void *arg, int ch, int nb_jobs)
  {
      AudioSurroundContext *s = ctx->priv;
      const float level_in = s->input_levels[ch];
      float *dst;
      int n;
  
      memset(s->input->extended_data[ch] + s->buf_size * sizeof(float), 0, s->buf_size * sizeof(float));
  
      dst = (float *)s->input->extended_data[ch];
      for (n = 0; n < s->buf_size; n++) {
          dst[n] *= s->window_func_lut[n] * level_in;
      }
  
      av_rdft_calc(s->rdft[ch], (float *)s->input->extended_data[ch]);
  
      return 0;
  }
  
  static int ifft_channel(AVFilterContext *ctx, void *arg, int ch, int nb_jobs)
  {
      AudioSurroundContext *s = ctx->priv;
      const float level_out = s->output_levels[ch];
      AVFrame *out = arg;
      float *dst, *ptr;
      int n;
  
      av_rdft_calc(s->irdft[ch], (float *)s->output->extended_data[ch]);
  
      dst = (float *)s->output->extended_data[ch];
      ptr = (float *)s->overlap_buffer->extended_data[ch];
  
      memmove(s->overlap_buffer->extended_data[ch],
              s->overlap_buffer->extended_data[ch] + s->hop_size * sizeof(float),
              s->buf_size * sizeof(float));
      memset(s->overlap_buffer->extended_data[ch] + s->buf_size * sizeof(float),
             0, s->hop_size * sizeof(float));
  
      for (n = 0; n < s->buf_size; n++) {
          ptr[n] += dst[n] * s->window_func_lut[n] * level_out;
      }
  
      ptr = (float *)s->overlap_buffer->extended_data[ch];
      dst = (float *)out->extended_data[ch];
      memcpy(dst, ptr, s->hop_size * sizeof(float));
  
      return 0;
  }
  
  static int filter_frame(AVFilterLink *inlink)
  {
      AVFilterContext *ctx = inlink->dst;
      AVFilterLink *outlink = ctx->outputs[0];
      AudioSurroundContext *s = ctx->priv;
      AVFrame *out;
      int ret;
  
      ret = av_audio_fifo_peek(s->fifo, (void **)s->input->extended_data, s->buf_size);
      if (ret < 0)
          return ret;
  
      ctx->internal->execute(ctx, fft_channel, NULL, NULL, inlink->channels);
  
      s->filter(ctx);
  
      out = ff_get_audio_buffer(outlink, s->hop_size);
      if (!out)
          return AVERROR(ENOMEM);
  
      ctx->internal->execute(ctx, ifft_channel, out, NULL, outlink->channels);
  
      out->pts = s->pts;
      if (s->pts != AV_NOPTS_VALUE)
          s->pts += av_rescale_q(out->nb_samples, (AVRational){1, outlink->sample_rate}, outlink->time_base);
      av_audio_fifo_drain(s->fifo, FFMIN(av_audio_fifo_size(s->fifo), s->hop_size));
  
      return ff_filter_frame(outlink, out);
  }
  
  static int activate(AVFilterContext *ctx)
  {
      AVFilterLink *inlink = ctx->inputs[0];
      AVFilterLink *outlink = ctx->outputs[0];
      AudioSurroundContext *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->buf_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->buf_size) ||
          (av_audio_fifo_size(s->fifo) > 0 && s->eof)) {
          ret = filter_frame(inlink);
          if (av_audio_fifo_size(s->fifo) >= s->buf_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 av_cold void uninit(AVFilterContext *ctx)
  {
      AudioSurroundContext *s = ctx->priv;
      int ch;
  
      av_frame_free(&s->input);
      av_frame_free(&s->output);
      av_frame_free(&s->overlap_buffer);
  
      for (ch = 0; ch < s->nb_in_channels; ch++) {
          av_rdft_end(s->rdft[ch]);
      }
      for (ch = 0; ch < s->nb_out_channels; ch++) {
          av_rdft_end(s->irdft[ch]);
      }
      av_freep(&s->input_levels);
      av_freep(&s->output_levels);
      av_freep(&s->rdft);
      av_freep(&s->irdft);
      av_audio_fifo_free(s->fifo);
      av_freep(&s->window_func_lut);
  }
  
  #define OFFSET(x) offsetof(AudioSurroundContext, x)
  #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
  
  static const AVOption surround_options[] = {
      { "chl_out",   "set output channel layout", OFFSET(out_channel_layout_str), AV_OPT_TYPE_STRING, {.str="5.1"}, 0,   0, FLAGS },
      { "chl_in",    "set input channel layout",  OFFSET(in_channel_layout_str),  AV_OPT_TYPE_STRING, {.str="stereo"},0, 0, FLAGS },
      { "level_in",  "set input level",           OFFSET(level_in),               AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  10, FLAGS },
      { "level_out", "set output level",          OFFSET(level_out),              AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  10, FLAGS },
      { "lfe",       "output LFE",                OFFSET(output_lfe),             AV_OPT_TYPE_BOOL,   {.i64=1},     0,   1, FLAGS },
      { "lfe_low",   "LFE low cut off",           OFFSET(lowcutf),                AV_OPT_TYPE_INT,    {.i64=128},   0, 256, FLAGS },
      { "lfe_high",  "LFE high cut off",          OFFSET(highcutf),               AV_OPT_TYPE_INT,    {.i64=256},   0, 512, FLAGS },
      { "lfe_mode",  "set LFE channel mode",      OFFSET(lfe_mode),               AV_OPT_TYPE_INT,    {.i64=0},     0,   1, FLAGS, "lfe_mode" },
      {  "add",      "just add LFE channel",                  0,                  AV_OPT_TYPE_CONST,  {.i64=0},     0,   1, FLAGS, "lfe_mode" },
      {  "sub",      "substract LFE channel with others",     0,                  AV_OPT_TYPE_CONST,  {.i64=1},     0,   1, FLAGS, "lfe_mode" },
      { "angle",     "set soundfield transform angle",        OFFSET(angle),      AV_OPT_TYPE_FLOAT,  {.dbl=90},    0, 360, FLAGS },
      { "fc_in",     "set front center channel input level",  OFFSET(fc_in),      AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  10, FLAGS },
      { "fc_out",    "set front center channel output level", OFFSET(fc_out),     AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  10, FLAGS },
      { "fl_in",     "set front left channel input level",    OFFSET(fl_in),      AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  10, FLAGS },
      { "fl_out",    "set front left channel output level",   OFFSET(fl_out),     AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  10, FLAGS },
      { "fr_in",     "set front right channel input level",   OFFSET(fr_in),      AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  10, FLAGS },
      { "fr_out",    "set front right channel output level",  OFFSET(fr_out),     AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  10, FLAGS },
      { "sl_in",     "set side left channel input level",     OFFSET(sl_in),      AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  10, FLAGS },
      { "sl_out",    "set side left channel output level",    OFFSET(sl_out),     AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  10, FLAGS },
      { "sr_in",     "set side right channel input level",    OFFSET(sr_in),      AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  10, FLAGS },
      { "sr_out",    "set side right channel output level",   OFFSET(sr_out),     AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  10, FLAGS },
      { "bl_in",     "set back left channel input level",     OFFSET(bl_in),      AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  10, FLAGS },
      { "bl_out",    "set back left channel output level",    OFFSET(bl_out),     AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  10, FLAGS },
      { "br_in",     "set back right channel input level",    OFFSET(br_in),      AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  10, FLAGS },
      { "br_out",    "set back right channel output level",   OFFSET(br_out),     AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  10, FLAGS },
      { "bc_in",     "set back center channel input level",   OFFSET(bc_in),      AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  10, FLAGS },
      { "bc_out",    "set back center channel output level",  OFFSET(bc_out),     AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  10, FLAGS },
      { "lfe_in",    "set lfe channel input level",  OFFSET(lfe_in),              AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  10, FLAGS },
      { "lfe_out",   "set lfe channel output level", OFFSET(lfe_out),             AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  10, FLAGS },
      { "allx",      "set all channel's x spread",         OFFSET(all_x),         AV_OPT_TYPE_FLOAT,  {.dbl=-1},   -1,  15, FLAGS },
      { "ally",      "set all channel's y spread",         OFFSET(all_y),         AV_OPT_TYPE_FLOAT,  {.dbl=-1},   -1,  15, FLAGS },
      { "fcx",       "set front center channel x spread",  OFFSET(fc_x),          AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  15, FLAGS },
      { "flx",       "set front left channel x spread",    OFFSET(fl_x),          AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  15, FLAGS },
      { "frx",       "set front right channel x spread",   OFFSET(fr_x),          AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  15, FLAGS },
      { "blx",       "set back left channel x spread",     OFFSET(bl_x),          AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  15, FLAGS },
      { "brx",       "set back right channel x spread",    OFFSET(br_x),          AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  15, FLAGS },
      { "slx",       "set side left channel x spread",     OFFSET(sl_x),          AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  15, FLAGS },
      { "srx",       "set side right channel x spread",    OFFSET(sr_x),          AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  15, FLAGS },
      { "bcx",       "set back center channel x spread",   OFFSET(bc_x),          AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  15, FLAGS },
      { "fcy",       "set front center channel y spread",  OFFSET(fc_y),          AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  15, FLAGS },
      { "fly",       "set front left channel y spread",    OFFSET(fl_y),          AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  15, FLAGS },
      { "fry",       "set front right channel y spread",   OFFSET(fr_y),          AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  15, FLAGS },
      { "bly",       "set back left channel y spread",     OFFSET(bl_y),          AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  15, FLAGS },
      { "bry",       "set back right channel y spread",    OFFSET(br_y),          AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  15, FLAGS },
      { "sly",       "set side left channel y spread",     OFFSET(sl_y),          AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  15, FLAGS },
      { "sry",       "set side right channel y spread",    OFFSET(sr_y),          AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  15, FLAGS },
      { "bcy",       "set back center channel y spread",   OFFSET(bc_y),          AV_OPT_TYPE_FLOAT,  {.dbl=1},     0,  15, FLAGS },
      { "win_size", "set window size", OFFSET(win_size), AV_OPT_TYPE_INT, {.i64 = 4096}, 1024, 65536, FLAGS },
      { "win_func", "set window function", OFFSET(win_func), AV_OPT_TYPE_INT, {.i64 = WFUNC_HANNING}, 0, NB_WFUNC-1, FLAGS, "win_func" },
          { "rect",     "Rectangular",      0, AV_OPT_TYPE_CONST, {.i64=WFUNC_RECT},     0, 0, FLAGS, "win_func" },
          { "bartlett", "Bartlett",         0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BARTLETT}, 0, 0, FLAGS, "win_func" },
          { "hann",     "Hann",             0, AV_OPT_TYPE_CONST, {.i64=WFUNC_HANNING},  0, 0, FLAGS, "win_func" },
          { "hanning",  "Hanning",          0, AV_OPT_TYPE_CONST, {.i64=WFUNC_HANNING},  0, 0, FLAGS, "win_func" },
          { "hamming",  "Hamming",          0, AV_OPT_TYPE_CONST, {.i64=WFUNC_HAMMING},  0, 0, FLAGS, "win_func" },
          { "blackman", "Blackman",         0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BLACKMAN}, 0, 0, FLAGS, "win_func" },
          { "welch",    "Welch",            0, AV_OPT_TYPE_CONST, {.i64=WFUNC_WELCH},    0, 0, FLAGS, "win_func" },
          { "flattop",  "Flat-top",         0, AV_OPT_TYPE_CONST, {.i64=WFUNC_FLATTOP},  0, 0, FLAGS, "win_func" },
          { "bharris",  "Blackman-Harris",  0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BHARRIS},  0, 0, FLAGS, "win_func" },
          { "bnuttall", "Blackman-Nuttall", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BNUTTALL}, 0, 0, FLAGS, "win_func" },
          { "bhann",    "Bartlett-Hann",    0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BHANN},    0, 0, FLAGS, "win_func" },
          { "sine",     "Sine",             0, AV_OPT_TYPE_CONST, {.i64=WFUNC_SINE},     0, 0, FLAGS, "win_func" },
          { "nuttall",  "Nuttall",          0, AV_OPT_TYPE_CONST, {.i64=WFUNC_NUTTALL},  0, 0, FLAGS, "win_func" },
          { "lanczos",  "Lanczos",          0, AV_OPT_TYPE_CONST, {.i64=WFUNC_LANCZOS},  0, 0, FLAGS, "win_func" },
          { "gauss",    "Gauss",            0, AV_OPT_TYPE_CONST, {.i64=WFUNC_GAUSS},    0, 0, FLAGS, "win_func" },
          { "tukey",    "Tukey",            0, AV_OPT_TYPE_CONST, {.i64=WFUNC_TUKEY},    0, 0, FLAGS, "win_func" },
          { "dolph",    "Dolph-Chebyshev",  0, AV_OPT_TYPE_CONST, {.i64=WFUNC_DOLPH},    0, 0, FLAGS, "win_func" },
          { "cauchy",   "Cauchy",           0, AV_OPT_TYPE_CONST, {.i64=WFUNC_CAUCHY},   0, 0, FLAGS, "win_func" },
          { "parzen",   "Parzen",           0, AV_OPT_TYPE_CONST, {.i64=WFUNC_PARZEN},   0, 0, FLAGS, "win_func" },
          { "poisson",  "Poisson",          0, AV_OPT_TYPE_CONST, {.i64=WFUNC_POISSON},  0, 0, FLAGS, "win_func" },
          { "bohman",   "Bohman",           0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BOHMAN},   0, 0, FLAGS, "win_func" },
      { "overlap", "set window overlap", OFFSET(overlap), AV_OPT_TYPE_FLOAT, {.dbl=0.5}, 0, 1, FLAGS },
      { NULL }
  };
  
  AVFILTER_DEFINE_CLASS(surround);
  
  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,
          .config_props  = config_output,
      },
      { NULL }
  };
  
  AVFilter ff_af_surround = {
      .name           = "surround",
      .description    = NULL_IF_CONFIG_SMALL("Apply audio surround upmix filter."),
      .query_formats  = query_formats,
      .priv_size      = sizeof(AudioSurroundContext),
      .priv_class     = &surround_class,
      .init           = init,
      .uninit         = uninit,
      .activate       = activate,
      .inputs         = inputs,
      .outputs        = outputs,
      .flags          = AVFILTER_FLAG_SLICE_THREADS,
  };
  