text: /*
   * Copyright (c) 2011 Stefano Sabatini
   *
   * 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
   * eval audio source
   */
  
  #include "libavutil/avassert.h"
  #include "libavutil/avstring.h"
  #include "libavutil/channel_layout.h"
  #include "libavutil/eval.h"
  #include "libavutil/opt.h"
  #include "libavutil/parseutils.h"
  #include "avfilter.h"
  #include "audio.h"
  #include "internal.h"
  
  static const char * const var_names[] = {
      "ch",           ///< the value of the current channel
      "n",            ///< number of frame
      "nb_in_channels",
      "nb_out_channels",
      "t",            ///< timestamp expressed in seconds
      "s",            ///< sample rate
      NULL
  };
  
  enum var_name {
      VAR_CH,
      VAR_N,
      VAR_NB_IN_CHANNELS,
      VAR_NB_OUT_CHANNELS,
      VAR_T,
      VAR_S,
      VAR_VARS_NB
  };
  
  typedef struct EvalContext {
      const AVClass *class;
      char *sample_rate_str;
      int sample_rate;
      int64_t chlayout;
      char *chlayout_str;
      int nb_channels;            ///< number of output channels
      int nb_in_channels;         ///< number of input channels
      int same_chlayout;          ///< set output as input channel layout
      int64_t pts;
      AVExpr **expr;
      char *exprs;
      int nb_samples;             ///< number of samples per requested frame
      int64_t duration;
      uint64_t n;
      double var_values[VAR_VARS_NB];
      double *channel_values;
      int64_t out_channel_layout;
  } EvalContext;
  
  static double val(void *priv, double ch)
  {
      EvalContext *eval = priv;
      return eval->channel_values[FFMIN((int)ch, eval->nb_in_channels-1)];
  }
  
  static double (* const aeval_func1[])(void *, double) = { val, NULL };
  static const char * const aeval_func1_names[] = { "val", NULL };
  
  #define OFFSET(x) offsetof(EvalContext, x)
  #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
  
  static const AVOption aevalsrc_options[]= {
      { "exprs",       "set the '|'-separated list of channels expressions", OFFSET(exprs), AV_OPT_TYPE_STRING, {.str = NULL}, .flags = FLAGS },
      { "nb_samples",  "set the number of samples per requested frame", OFFSET(nb_samples),      AV_OPT_TYPE_INT,    {.i64 = 1024},    0,        INT_MAX, FLAGS },
      { "n",           "set the number of samples per requested frame", OFFSET(nb_samples),      AV_OPT_TYPE_INT,    {.i64 = 1024},    0,        INT_MAX, FLAGS },
      { "sample_rate", "set the sample rate",                           OFFSET(sample_rate_str), AV_OPT_TYPE_STRING, {.str = "44100"}, CHAR_MIN, CHAR_MAX, FLAGS },
      { "s",           "set the sample rate",                           OFFSET(sample_rate_str), AV_OPT_TYPE_STRING, {.str = "44100"}, CHAR_MIN, CHAR_MAX, FLAGS },
      { "duration",    "set audio duration", OFFSET(duration), AV_OPT_TYPE_DURATION, {.i64 = -1}, -1, INT64_MAX, FLAGS },
      { "d",           "set audio duration", OFFSET(duration), AV_OPT_TYPE_DURATION, {.i64 = -1}, -1, INT64_MAX, FLAGS },
      { "channel_layout", "set channel layout", OFFSET(chlayout_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, FLAGS },
      { "c",              "set channel layout", OFFSET(chlayout_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, FLAGS },
      { NULL }
  };
  
  AVFILTER_DEFINE_CLASS(aevalsrc);
  
  static int parse_channel_expressions(AVFilterContext *ctx,
                                       int expected_nb_channels)
  {
      EvalContext *eval = ctx->priv;
      char *args1 = av_strdup(eval->exprs);
      char *expr, *last_expr = NULL, *buf;
      double (* const *func1)(void *, double) = NULL;
      const char * const *func1_names = NULL;
      int i, ret = 0;
  
      if (!args1)
          return AVERROR(ENOMEM);
  
      if (!eval->exprs) {
          av_log(ctx, AV_LOG_ERROR, "Channels expressions list is empty\n");
          return AVERROR(EINVAL);
      }
  
      if (!strcmp(ctx->filter->name, "aeval")) {
          func1 = aeval_func1;
          func1_names = aeval_func1_names;
      }
  
  #define ADD_EXPRESSION(expr_) do {                                      \
          if (!av_dynarray2_add((void **)&eval->expr, &eval->nb_channels, \
                                sizeof(*eval->expr), NULL)) {             \
              ret = AVERROR(ENOMEM);                                      \
              goto end;                                                   \
          }                                                               \
          eval->expr[eval->nb_channels-1] = NULL;                         \
          ret = av_expr_parse(&eval->expr[eval->nb_channels - 1], expr_,  \
                              var_names, func1_names, func1,              \
                              NULL, NULL, 0, ctx);                        \
          if (ret < 0)                                                    \
              goto end;                                                   \
      } while (0)
  
      /* reset expressions */
      for (i = 0; i < eval->nb_channels; i++) {
          av_expr_free(eval->expr[i]);
          eval->expr[i] = NULL;
      }
      av_freep(&eval->expr);
      eval->nb_channels = 0;
  
      buf = args1;
      while (expr = av_strtok(buf, "|", &buf)) {
          ADD_EXPRESSION(expr);
          last_expr = expr;
      }
  
      if (expected_nb_channels > eval->nb_channels)
          for (i = eval->nb_channels; i < expected_nb_channels; i++)
              ADD_EXPRESSION(last_expr);
  
      if (expected_nb_channels > 0 && eval->nb_channels != expected_nb_channels) {
          av_log(ctx, AV_LOG_ERROR,
                 "Mismatch between the specified number of channel expressions '%d' "
                 "and the number of expected output channels '%d' for the specified channel layout\n",
                 eval->nb_channels, expected_nb_channels);
          ret = AVERROR(EINVAL);
          goto end;
      }
  
  end:
      av_free(args1);
      return ret;
  }
  
  static av_cold int init(AVFilterContext *ctx)
  {
      EvalContext *eval = ctx->priv;
      int ret = 0;
  
      if (eval->chlayout_str) {
          if (!strcmp(eval->chlayout_str, "same") && !strcmp(ctx->filter->name, "aeval")) {
              eval->same_chlayout = 1;
          } else {
              ret = ff_parse_channel_layout(&eval->chlayout, NULL, eval->chlayout_str, ctx);
              if (ret < 0)
                  return ret;
  
              ret = parse_channel_expressions(ctx, av_get_channel_layout_nb_channels(eval->chlayout));
              if (ret < 0)
                  return ret;
          }
      } else {
          /* guess channel layout from nb expressions/channels */
          if ((ret = parse_channel_expressions(ctx, -1)) < 0)
              return ret;
  
          eval->chlayout = av_get_default_channel_layout(eval->nb_channels);
          if (!eval->chlayout && eval->nb_channels <= 0) {
              av_log(ctx, AV_LOG_ERROR, "Invalid number of channels '%d' provided\n",
                     eval->nb_channels);
              return AVERROR(EINVAL);
          }
      }
  
      if (eval->sample_rate_str)
          if ((ret = ff_parse_sample_rate(&eval->sample_rate, eval->sample_rate_str, ctx)))
              return ret;
      eval->n = 0;
  
      return ret;
  }
  
  static av_cold void uninit(AVFilterContext *ctx)
  {
      EvalContext *eval = ctx->priv;
      int i;
  
      for (i = 0; i < eval->nb_channels; i++) {
          av_expr_free(eval->expr[i]);
          eval->expr[i] = NULL;
      }
      av_freep(&eval->expr);
      av_freep(&eval->channel_values);
  }
  
  static int config_props(AVFilterLink *outlink)
  {
      EvalContext *eval = outlink->src->priv;
      char buf[128];
  
      outlink->time_base = (AVRational){1, eval->sample_rate};
      outlink->sample_rate = eval->sample_rate;
  
      eval->var_values[VAR_S] = eval->sample_rate;
      eval->var_values[VAR_NB_IN_CHANNELS] = NAN;
      eval->var_values[VAR_NB_OUT_CHANNELS] = outlink->channels;
  
      av_get_channel_layout_string(buf, sizeof(buf), 0, eval->chlayout);
  
      av_log(outlink->src, AV_LOG_VERBOSE,
             "sample_rate:%d chlayout:%s duration:%"PRId64"\n",
             eval->sample_rate, buf, eval->duration);
  
      return 0;
  }
  
  static int query_formats(AVFilterContext *ctx)
  {
      EvalContext *eval = ctx->priv;
      static const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_DBLP, AV_SAMPLE_FMT_NONE };
      int64_t chlayouts[] = { eval->chlayout ? eval->chlayout : FF_COUNT2LAYOUT(eval->nb_channels) , -1 };
      int sample_rates[] = { eval->sample_rate, -1 };
      AVFilterFormats *formats;
      AVFilterChannelLayouts *layouts;
      int ret;
  
      formats = ff_make_format_list(sample_fmts);
      if (!formats)
          return AVERROR(ENOMEM);
      ret = ff_set_common_formats (ctx, formats);
      if (ret < 0)
          return ret;
  
      layouts = avfilter_make_format64_list(chlayouts);
      if (!layouts)
          return AVERROR(ENOMEM);
      ret = ff_set_common_channel_layouts(ctx, layouts);
      if (ret < 0)
          return ret;
  
      formats = ff_make_format_list(sample_rates);
      if (!formats)
          return AVERROR(ENOMEM);
      return ff_set_common_samplerates(ctx, formats);
  }
  
  static int request_frame(AVFilterLink *outlink)
  {
      EvalContext *eval = outlink->src->priv;
      AVFrame *samplesref;
      int i, j;
      int64_t t = av_rescale(eval->n, AV_TIME_BASE, eval->sample_rate);
      int nb_samples;
  
      if (eval->duration >= 0 && t >= eval->duration)
          return AVERROR_EOF;
  
      if (eval->duration >= 0) {
          nb_samples = FFMIN(eval->nb_samples, av_rescale(eval->duration, eval->sample_rate, AV_TIME_BASE) - eval->pts);
          if (!nb_samples)
              return AVERROR_EOF;
      } else {
          nb_samples = eval->nb_samples;
      }
      samplesref = ff_get_audio_buffer(outlink, nb_samples);
      if (!samplesref)
          return AVERROR(ENOMEM);
  
      /* evaluate expression for each single sample and for each channel */
      for (i = 0; i < nb_samples; i++, eval->n++) {
          eval->var_values[VAR_N] = eval->n;
          eval->var_values[VAR_T] = eval->var_values[VAR_N] * (double)1/eval->sample_rate;
  
          for (j = 0; j < eval->nb_channels; j++) {
              *((double *) samplesref->extended_data[j] + i) =
                  av_expr_eval(eval->expr[j], eval->var_values, NULL);
          }
      }
  
      samplesref->pts = eval->pts;
      samplesref->sample_rate = eval->sample_rate;
      eval->pts += nb_samples;
  
      return ff_filter_frame(outlink, samplesref);
  }
  
  #if CONFIG_AEVALSRC_FILTER
  static const AVFilterPad aevalsrc_outputs[] = {
      {
          .name          = "default",
          .type          = AVMEDIA_TYPE_AUDIO,
          .config_props  = config_props,
          .request_frame = request_frame,
      },
      { NULL }
  };
  
  AVFilter ff_asrc_aevalsrc = {
      .name          = "aevalsrc",
      .description   = NULL_IF_CONFIG_SMALL("Generate an audio signal generated by an expression."),
      .query_formats = query_formats,
      .init          = init,
      .uninit        = uninit,
      .priv_size     = sizeof(EvalContext),
      .inputs        = NULL,
      .outputs       = aevalsrc_outputs,
      .priv_class    = &aevalsrc_class,
  };
  
  #endif /* CONFIG_AEVALSRC_FILTER */
  
  #define OFFSET(x) offsetof(EvalContext, x)
  #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
  
  static const AVOption aeval_options[]= {
      { "exprs", "set the '|'-separated list of channels expressions", OFFSET(exprs), AV_OPT_TYPE_STRING, {.str = NULL}, .flags = FLAGS },
      { "channel_layout", "set channel layout", OFFSET(chlayout_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, FLAGS },
      { "c",              "set channel layout", OFFSET(chlayout_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, FLAGS },
      { NULL }
  };
  
  AVFILTER_DEFINE_CLASS(aeval);
  
  static int aeval_query_formats(AVFilterContext *ctx)
  {
      AVFilterFormats *formats = NULL;
      AVFilterChannelLayouts *layouts;
      AVFilterLink *inlink  = ctx->inputs[0];
      AVFilterLink *outlink  = ctx->outputs[0];
      EvalContext *eval = ctx->priv;
      static const enum AVSampleFormat sample_fmts[] = {
          AV_SAMPLE_FMT_DBLP, AV_SAMPLE_FMT_NONE
      };
      int ret;
  
      // inlink supports any channel layout
      layouts = ff_all_channel_counts();
      if ((ret = ff_channel_layouts_ref(layouts, &inlink->out_channel_layouts)) < 0)
          return ret;
  
      if (eval->same_chlayout) {
          layouts = ff_all_channel_counts();
          if ((ret = ff_set_common_channel_layouts(ctx, layouts)) < 0)
              return ret;
      } else {
          // outlink supports only requested output channel layout
          layouts = NULL;
          if ((ret = ff_add_channel_layout(&layouts,
                                eval->out_channel_layout ? eval->out_channel_layout :
                                FF_COUNT2LAYOUT(eval->nb_channels))) < 0)
              return ret;
          if ((ret = ff_channel_layouts_ref(layouts, &outlink->in_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 aeval_config_output(AVFilterLink *outlink)
  {
      AVFilterContext *ctx = outlink->src;
      EvalContext *eval = ctx->priv;
      AVFilterLink *inlink = ctx->inputs[0];
      int ret;
  
      if (eval->same_chlayout) {
          eval->chlayout = inlink->channel_layout;
  
          if ((ret = parse_channel_expressions(ctx, inlink->channels)) < 0)
              return ret;
      }
  
      eval->n = 0;
      eval->nb_in_channels = eval->var_values[VAR_NB_IN_CHANNELS] = inlink->channels;
      eval->var_values[VAR_NB_OUT_CHANNELS] = outlink->channels;
      eval->var_values[VAR_S] = inlink->sample_rate;
      eval->var_values[VAR_T] = NAN;
  
      eval->channel_values = av_realloc_f(eval->channel_values,
                                          inlink->channels, sizeof(*eval->channel_values));
      if (!eval->channel_values)
          return AVERROR(ENOMEM);
  
      return 0;
  }
  
  #define TS2T(ts, tb) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts)*av_q2d(tb))
  
  static int filter_frame(AVFilterLink *inlink, AVFrame *in)
  {
      EvalContext *eval     = inlink->dst->priv;
      AVFilterLink *outlink = inlink->dst->outputs[0];
      int nb_samples        = in->nb_samples;
      AVFrame *out;
      double t0;
      int i, j;
  
      out = ff_get_audio_buffer(outlink, nb_samples);
      if (!out) {
          av_frame_free(&in);
          return AVERROR(ENOMEM);
      }
      av_frame_copy_props(out, in);
  
      t0 = TS2T(in->pts, inlink->time_base);
  
      /* evaluate expression for each single sample and for each channel */
      for (i = 0; i < nb_samples; i++, eval->n++) {
          eval->var_values[VAR_N] = eval->n;
          eval->var_values[VAR_T] = t0 + i * (double)1/inlink->sample_rate;
  
          for (j = 0; j < inlink->channels; j++)
              eval->channel_values[j] = *((double *) in->extended_data[j] + i);
  
          for (j = 0; j < outlink->channels; j++) {
              eval->var_values[VAR_CH] = j;
              *((double *) out->extended_data[j] + i) =
                  av_expr_eval(eval->expr[j], eval->var_values, eval);
          }
      }
  
      av_frame_free(&in);
      return ff_filter_frame(outlink, out);
  }
  
  #if CONFIG_AEVAL_FILTER
  
  static const AVFilterPad aeval_inputs[] = {
      {
          .name           = "default",
          .type           = AVMEDIA_TYPE_AUDIO,
          .filter_frame   = filter_frame,
      },
      { NULL }
  };
  
  static const AVFilterPad aeval_outputs[] = {
      {
          .name          = "default",
          .type          = AVMEDIA_TYPE_AUDIO,
          .config_props  = aeval_config_output,
      },
      { NULL }
  };
  
  AVFilter ff_af_aeval = {
      .name          = "aeval",
      .description   = NULL_IF_CONFIG_SMALL("Filter audio signal according to a specified expression."),
      .query_formats = aeval_query_formats,
      .init          = init,
      .uninit        = uninit,
      .priv_size     = sizeof(EvalContext),
      .inputs        = aeval_inputs,
      .outputs       = aeval_outputs,
      .priv_class    = &aeval_class,
  };
  
  #endif /* CONFIG_AEVAL_FILTER */
  