text: /*
   * 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 <stdlib.h>
  
  #include "libavutil/common.h"
  #include "libavutil/opt.h"
  
  #include "bsf.h"
  #include "bsf_internal.h"
  #include "cbs.h"
  
  
  typedef struct FilterUnitsContext {
      const AVClass *class;
  
      CodedBitstreamContext *cbc;
      CodedBitstreamFragment fragment;
  
      const char *pass_types;
      const char *remove_types;
  
      enum {
          NOOP,
          PASS,
          REMOVE,
      } mode;
      CodedBitstreamUnitType *type_list;
      int nb_types;
  } FilterUnitsContext;
  
  
  static int filter_units_make_type_list(const char *list_string,
                                         CodedBitstreamUnitType **type_list,
                                         int *nb_types)
  {
      CodedBitstreamUnitType *list = NULL;
      int pass, count;
  
      for (pass = 1; pass <= 2; pass++) {
          long value, range_start, range_end;
          const char *str;
          char *value_end;
  
          count = 0;
          for (str = list_string; *str;) {
              value = strtol(str, &value_end, 0);
              if (str == value_end)
                  goto invalid;
              str = (const char *)value_end;
              if (*str == '-') {
                  ++str;
                  range_start = value;
                  range_end   = strtol(str, &value_end, 0);
                  if (str == value_end)
                      goto invalid;
  
                  for (value = range_start; value < range_end; value++) {
                      if (pass == 2)
                          list[count] = value;
                      ++count;
                  }
              } else {
                  if (pass == 2)
                      list[count] = value;
                  ++count;
              }
              if (*str == '|')
                  ++str;
          }
          if (pass == 1) {
              list = av_malloc_array(count, sizeof(*list));
              if (!list)
                  return AVERROR(ENOMEM);
          }
      }
  
      *type_list = list;
      *nb_types  = count;
      return 0;
  
  invalid:
      av_freep(&list);
      return AVERROR(EINVAL);
  }
  
  static int filter_units_filter(AVBSFContext *bsf, AVPacket *pkt)
  {
      FilterUnitsContext      *ctx = bsf->priv_data;
      CodedBitstreamFragment *frag = &ctx->fragment;
      int err, i, j;
  
      err = ff_bsf_get_packet_ref(bsf, pkt);
      if (err < 0)
          return err;
  
      if (ctx->mode == NOOP)
          return 0;
  
      err = ff_cbs_read_packet(ctx->cbc, frag, pkt);
      if (err < 0) {
          av_log(bsf, AV_LOG_ERROR, "Failed to read packet.\n");
          goto fail;
      }
  
      for (i = frag->nb_units - 1; i >= 0; i--) {
          for (j = 0; j < ctx->nb_types; j++) {
              if (frag->units[i].type == ctx->type_list[j])
                  break;
          }
          if (ctx->mode == REMOVE ? j <  ctx->nb_types
                                  : j >= ctx->nb_types)
              ff_cbs_delete_unit(frag, i);
      }
  
      if (frag->nb_units == 0) {
          // Don't return packets with nothing in them.
          err = AVERROR(EAGAIN);
          goto fail;
      }
  
      err = ff_cbs_write_packet(ctx->cbc, pkt, frag);
      if (err < 0) {
          av_log(bsf, AV_LOG_ERROR, "Failed to write packet.\n");
          goto fail;
      }
  
  fail:
      if (err < 0)
          av_packet_unref(pkt);
      ff_cbs_fragment_reset(frag);
  
      return err;
  }
  
  static int filter_units_init(AVBSFContext *bsf)
  {
      FilterUnitsContext *ctx = bsf->priv_data;
      int err;
  
      if (ctx->pass_types && ctx->remove_types) {
          av_log(bsf, AV_LOG_ERROR, "Exactly one of pass_types or "
                 "remove_types is required.\n");
          return AVERROR(EINVAL);
      }
  
      if (ctx->pass_types) {
          ctx->mode = PASS;
          err = filter_units_make_type_list(ctx->pass_types,
                                            &ctx->type_list, &ctx->nb_types);
          if (err < 0) {
              av_log(bsf, AV_LOG_ERROR, "Failed to parse pass_types.\n");
              return err;
          }
      } else if (ctx->remove_types) {
          ctx->mode = REMOVE;
          err = filter_units_make_type_list(ctx->remove_types,
                                            &ctx->type_list, &ctx->nb_types);
          if (err < 0) {
              av_log(bsf, AV_LOG_ERROR, "Failed to parse remove_types.\n");
              return err;
          }
      } else {
          return 0;
      }
  
      err = ff_cbs_init(&ctx->cbc, bsf->par_in->codec_id, bsf);
      if (err < 0)
          return err;
  
      // Don't actually decompose anything, we only want the unit data.
      ctx->cbc->decompose_unit_types    = ctx->type_list;
      ctx->cbc->nb_decompose_unit_types = 0;
  
      if (bsf->par_in->extradata) {
          CodedBitstreamFragment *frag = &ctx->fragment;
  
          err = ff_cbs_read_extradata(ctx->cbc, frag, bsf->par_in);
          if (err < 0) {
              av_log(bsf, AV_LOG_ERROR, "Failed to read extradata.\n");
          } else {
              err = ff_cbs_write_extradata(ctx->cbc, bsf->par_out, frag);
              if (err < 0)
                  av_log(bsf, AV_LOG_ERROR, "Failed to write extradata.\n");
          }
  
          ff_cbs_fragment_reset(frag);
      }
  
      return err;
  }
  
  static void filter_units_close(AVBSFContext *bsf)
  {
      FilterUnitsContext *ctx = bsf->priv_data;
  
      av_freep(&ctx->type_list);
  
      ff_cbs_fragment_free(&ctx->fragment);
      ff_cbs_close(&ctx->cbc);
  }
  
  #define OFFSET(x) offsetof(FilterUnitsContext, x)
  #define FLAGS (AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_BSF_PARAM)
  static const AVOption filter_units_options[] = {
      { "pass_types",   "List of unit types to pass through the filter.",
          OFFSET(pass_types),   AV_OPT_TYPE_STRING,
          { .str = NULL }, .flags = FLAGS },
      { "remove_types", "List of unit types to remove in the filter.",
          OFFSET(remove_types), AV_OPT_TYPE_STRING,
          { .str = NULL }, .flags = FLAGS },
  
      { NULL }
  };
  
  static const AVClass filter_units_class = {
      .class_name = "filter_units",
      .item_name  = av_default_item_name,
      .option     = filter_units_options,
      .version    = LIBAVUTIL_VERSION_INT,
  };
  
  const AVBitStreamFilter ff_filter_units_bsf = {
      .name           = "filter_units",
      .priv_data_size = sizeof(FilterUnitsContext),
      .priv_class     = &filter_units_class,
      .init           = &filter_units_init,
      .close          = &filter_units_close,
      .filter         = &filter_units_filter,
      .codec_ids      = ff_cbs_all_codec_ids,
  };
  