text: /*
   * Copyright (c) 2012 Nicolas George
   *
   * 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/avstring.h"
  #include "libavutil/avassert.h"
  #include "libavutil/bprint.h"
  #include "libavutil/intreadwrite.h"
  #include "libavutil/opt.h"
  #include "libavutil/parseutils.h"
  #include "libavutil/timestamp.h"
  #include "libavcodec/bsf.h"
  #include "avformat.h"
  #include "avio_internal.h"
  #include "internal.h"
  #include "url.h"
  
  typedef enum ConcatMatchMode {
      MATCH_ONE_TO_ONE,
      MATCH_EXACT_ID,
  } ConcatMatchMode;
  
  typedef struct ConcatStream {
      AVBSFContext *bsf;
      int out_stream_index;
  } ConcatStream;
  
  typedef struct {
      char *url;
      int64_t start_time;
      int64_t file_start_time;
      int64_t file_inpoint;
      int64_t duration;
      int64_t user_duration;
      int64_t next_dts;
      ConcatStream *streams;
      int64_t inpoint;
      int64_t outpoint;
      AVDictionary *metadata;
      AVDictionary *options;
      int nb_streams;
  } ConcatFile;
  
  typedef struct {
      AVClass *class;
      ConcatFile *files;
      ConcatFile *cur_file;
      unsigned nb_files;
      AVFormatContext *avf;
      int safe;
      int seekable;
      int eof;
      ConcatMatchMode stream_match_mode;
      unsigned auto_convert;
      int segment_time_metadata;
  } ConcatContext;
  
  static int concat_probe(const AVProbeData *probe)
  {
      return memcmp(probe->buf, "ffconcat version 1.0", 20) ?
             0 : AVPROBE_SCORE_MAX;
  }
  
  static char *get_keyword(uint8_t **cursor)
  {
      char *ret = *cursor += strspn(*cursor, SPACE_CHARS);
      *cursor += strcspn(*cursor, SPACE_CHARS);
      if (**cursor) {
          *((*cursor)++) = 0;
          *cursor += strspn(*cursor, SPACE_CHARS);
      }
      return ret;
  }
  
  static int safe_filename(const char *f)
  {
      const char *start = f;
  
      for (; *f; f++) {
          /* A-Za-z0-9_- */
          if (!((unsigned)((*f | 32) - 'a') < 26 ||
                (unsigned)(*f - '0') < 10 || *f == '_' || *f == '-')) {
              if (f == start)
                  return 0;
              else if (*f == '/')
                  start = f + 1;
              else if (*f != '.')
                  return 0;
          }
      }
      return 1;
  }
  
  #define FAIL(retcode) do { ret = (retcode); goto fail; } while(0)
  
  static int add_file(AVFormatContext *avf, char *filename, ConcatFile **rfile,
                      unsigned *nb_files_alloc)
  {
      ConcatContext *cat = avf->priv_data;
      ConcatFile *file;
      char *url = NULL;
      const char *proto;
      const char *ptr;
      size_t url_len;
      int ret;
  
      if (cat->safe && !safe_filename(filename)) {
          av_log(avf, AV_LOG_ERROR, "Unsafe file name '%s'\n", filename);
          FAIL(AVERROR(EPERM));
      }
  
      proto = avio_find_protocol_name(filename);
      if (proto && av_strstart(filename, proto, &ptr) &&
          (*ptr == ':' || *ptr == ',')) {
          url = filename;
          filename = NULL;
      } else {
          url_len = strlen(avf->url) + strlen(filename) + 16;
          if (!(url = av_malloc(url_len)))
              FAIL(AVERROR(ENOMEM));
          ff_make_absolute_url(url, url_len, avf->url, filename);
          av_freep(&filename);
      }
  
      if (cat->nb_files >= *nb_files_alloc) {
          size_t n = FFMAX(*nb_files_alloc * 2, 16);
          ConcatFile *new_files;
          if (n <= cat->nb_files || n > SIZE_MAX / sizeof(*cat->files) ||
              !(new_files = av_realloc(cat->files, n * sizeof(*cat->files))))
              FAIL(AVERROR(ENOMEM));
          cat->files = new_files;
          *nb_files_alloc = n;
      }
  
      file = &cat->files[cat->nb_files++];
      memset(file, 0, sizeof(*file));
      *rfile = file;
  
      file->url        = url;
      file->start_time = AV_NOPTS_VALUE;
      file->duration   = AV_NOPTS_VALUE;
      file->next_dts   = AV_NOPTS_VALUE;
      file->inpoint    = AV_NOPTS_VALUE;
      file->outpoint   = AV_NOPTS_VALUE;
      file->user_duration = AV_NOPTS_VALUE;
  
      return 0;
  
  fail:
      av_free(url);
      av_free(filename);
      return ret;
  }
  
  static int copy_stream_props(AVStream *st, AVStream *source_st)
  {
      int ret;
  
      if (st->codecpar->codec_id || !source_st->codecpar->codec_id) {
          if (st->codecpar->extradata_size < source_st->codecpar->extradata_size) {
              ret = ff_alloc_extradata(st->codecpar,
                                       source_st->codecpar->extradata_size);
              if (ret < 0)
                  return ret;
          }
          memcpy(st->codecpar->extradata, source_st->codecpar->extradata,
                 source_st->codecpar->extradata_size);
          return 0;
      }
      if ((ret = avcodec_parameters_copy(st->codecpar, source_st->codecpar)) < 0)
          return ret;
      st->r_frame_rate        = source_st->r_frame_rate;
      st->avg_frame_rate      = source_st->avg_frame_rate;
      st->sample_aspect_ratio = source_st->sample_aspect_ratio;
      avpriv_set_pts_info(st, 64, source_st->time_base.num, source_st->time_base.den);
  
      av_dict_copy(&st->metadata, source_st->metadata, 0);
      ff_stream_side_data_copy(st, source_st);
      return 0;
  }
  
  static int detect_stream_specific(AVFormatContext *avf, int idx)
  {
      ConcatContext *cat = avf->priv_data;
      AVStream *st = cat->avf->streams[idx];
      ConcatStream *cs = &cat->cur_file->streams[idx];
      const AVBitStreamFilter *filter;
      AVBSFContext *bsf;
      int ret;
  
      if (cat->auto_convert && st->codecpar->codec_id == AV_CODEC_ID_H264) {
          if (!st->codecpar->extradata_size                                                ||
              (st->codecpar->extradata_size >= 3 && AV_RB24(st->codecpar->extradata) == 1) ||
              (st->codecpar->extradata_size >= 4 && AV_RB32(st->codecpar->extradata) == 1))
              return 0;
          av_log(cat->avf, AV_LOG_INFO,
                 "Auto-inserting h264_mp4toannexb bitstream filter\n");
          filter = av_bsf_get_by_name("h264_mp4toannexb");
          if (!filter) {
              av_log(avf, AV_LOG_ERROR, "h264_mp4toannexb bitstream filter "
                     "required for H.264 streams\n");
              return AVERROR_BSF_NOT_FOUND;
          }
          ret = av_bsf_alloc(filter, &bsf);
          if (ret < 0)
              return ret;
          cs->bsf = bsf;
  
          ret = avcodec_parameters_copy(bsf->par_in, st->codecpar);
          if (ret < 0)
             return ret;
  
          ret = av_bsf_init(bsf);
          if (ret < 0)
              return ret;
  
          ret = avcodec_parameters_copy(st->codecpar, bsf->par_out);
          if (ret < 0)
              return ret;
      }
      return 0;
  }
  
  static int match_streams_one_to_one(AVFormatContext *avf)
  {
      ConcatContext *cat = avf->priv_data;
      AVStream *st;
      int i, ret;
  
      for (i = cat->cur_file->nb_streams; i < cat->avf->nb_streams; i++) {
          if (i < avf->nb_streams) {
              st = avf->streams[i];
          } else {
              if (!(st = avformat_new_stream(avf, NULL)))
                  return AVERROR(ENOMEM);
          }
          if ((ret = copy_stream_props(st, cat->avf->streams[i])) < 0)
              return ret;
          cat->cur_file->streams[i].out_stream_index = i;
      }
      return 0;
  }
  
  static int match_streams_exact_id(AVFormatContext *avf)
  {
      ConcatContext *cat = avf->priv_data;
      AVStream *st;
      int i, j, ret;
  
      for (i = cat->cur_file->nb_streams; i < cat->avf->nb_streams; i++) {
          st = cat->avf->streams[i];
          for (j = 0; j < avf->nb_streams; j++) {
              if (avf->streams[j]->id == st->id) {
                  av_log(avf, AV_LOG_VERBOSE,
                         "Match slave stream #%d with stream #%d id 0x%x\n",
                         i, j, st->id);
                  if ((ret = copy_stream_props(avf->streams[j], st)) < 0)
                      return ret;
                  cat->cur_file->streams[i].out_stream_index = j;
              }
          }
      }
      return 0;
  }
  
  static int match_streams(AVFormatContext *avf)
  {
      ConcatContext *cat = avf->priv_data;
      ConcatStream *map;
      int i, ret;
  
      if (cat->cur_file->nb_streams >= cat->avf->nb_streams)
          return 0;
      map = av_realloc(cat->cur_file->streams,
                       cat->avf->nb_streams * sizeof(*map));
      if (!map)
          return AVERROR(ENOMEM);
      cat->cur_file->streams = map;
      memset(map + cat->cur_file->nb_streams, 0,
             (cat->avf->nb_streams - cat->cur_file->nb_streams) * sizeof(*map));
  
      for (i = cat->cur_file->nb_streams; i < cat->avf->nb_streams; i++) {
          map[i].out_stream_index = -1;
          if ((ret = detect_stream_specific(avf, i)) < 0)
              return ret;
      }
      switch (cat->stream_match_mode) {
      case MATCH_ONE_TO_ONE:
          ret = match_streams_one_to_one(avf);
          break;
      case MATCH_EXACT_ID:
          ret = match_streams_exact_id(avf);
          break;
      default:
          ret = AVERROR_BUG;
      }
      if (ret < 0)
          return ret;
      cat->cur_file->nb_streams = cat->avf->nb_streams;
      return 0;
  }
  
  static int64_t get_best_effort_duration(ConcatFile *file, AVFormatContext *avf)
  {
      if (file->user_duration != AV_NOPTS_VALUE)
          return file->user_duration;
      if (file->outpoint != AV_NOPTS_VALUE)
          return file->outpoint - file->file_inpoint;
      if (avf->duration > 0)
          return avf->duration - (file->file_inpoint - file->file_start_time);
      if (file->next_dts != AV_NOPTS_VALUE)
          return file->next_dts - file->file_inpoint;
      return AV_NOPTS_VALUE;
  }
  
  static int open_file(AVFormatContext *avf, unsigned fileno)
  {
      ConcatContext *cat = avf->priv_data;
      ConcatFile *file = &cat->files[fileno];
      AVDictionary *options = NULL;
      int ret;
  
      if (cat->avf)
          avformat_close_input(&cat->avf);
  
      cat->avf = avformat_alloc_context();
      if (!cat->avf)
          return AVERROR(ENOMEM);
  
      cat->avf->flags |= avf->flags & ~AVFMT_FLAG_CUSTOM_IO;
      cat->avf->interrupt_callback = avf->interrupt_callback;
  
      if ((ret = ff_copy_whiteblacklists(cat->avf, avf)) < 0)
          return ret;
  
      ret = av_dict_copy(&options, file->options, 0);
      if (ret < 0)
          return ret;
  
      if ((ret = avformat_open_input(&cat->avf, file->url, NULL, &options)) < 0 ||
          (ret = avformat_find_stream_info(cat->avf, NULL)) < 0) {
          av_log(avf, AV_LOG_ERROR, "Impossible to open '%s'\n", file->url);
          av_dict_free(&options);
          avformat_close_input(&cat->avf);
          return ret;
      }
      if (options) {
          av_log(avf, AV_LOG_WARNING, "Unused options for '%s'.\n", file->url);
          /* TODO log unused options once we have a proper string API */
          av_dict_free(&options);
      }
      cat->cur_file = file;
      file->start_time = !fileno ? 0 :
                         cat->files[fileno - 1].start_time +
                         cat->files[fileno - 1].duration;
      file->file_start_time = (cat->avf->start_time == AV_NOPTS_VALUE) ? 0 : cat->avf->start_time;
      file->file_inpoint = (file->inpoint == AV_NOPTS_VALUE) ? file->file_start_time : file->inpoint;
      file->duration = get_best_effort_duration(file, cat->avf);
  
      if (cat->segment_time_metadata) {
          av_dict_set_int(&file->metadata, "lavf.concatdec.start_time", file->start_time, 0);
          if (file->duration != AV_NOPTS_VALUE)
              av_dict_set_int(&file->metadata, "lavf.concatdec.duration", file->duration, 0);
      }
  
      if ((ret = match_streams(avf)) < 0)
          return ret;
      if (file->inpoint != AV_NOPTS_VALUE) {
         if ((ret = avformat_seek_file(cat->avf, -1, INT64_MIN, file->inpoint, file->inpoint, 0)) < 0)
             return ret;
      }
      return 0;
  }
  
  static int concat_read_close(AVFormatContext *avf)
  {
      ConcatContext *cat = avf->priv_data;
      unsigned i, j;
  
      for (i = 0; i < cat->nb_files; i++) {
          av_freep(&cat->files[i].url);
          for (j = 0; j < cat->files[i].nb_streams; j++) {
              if (cat->files[i].streams[j].bsf)
                  av_bsf_free(&cat->files[i].streams[j].bsf);
          }
          av_freep(&cat->files[i].streams);
          av_dict_free(&cat->files[i].metadata);
          av_dict_free(&cat->files[i].options);
      }
      if (cat->avf)
          avformat_close_input(&cat->avf);
      av_freep(&cat->files);
      return 0;
  }
  
  #define MAX_ARGS 3
  #define NEEDS_UNSAFE   (1 << 0)
  #define NEEDS_FILE     (1 << 1)
  #define NEEDS_STREAM   (1 << 2)
  
  typedef struct ParseSyntax {
      const char *keyword;
      char args[MAX_ARGS];
      uint8_t flags;
  } ParseSyntax;
  
  typedef enum ParseDirective {
     DIR_FFCONCAT,
     DIR_FILE,
     DIR_DURATION,
     DIR_INPOINT,
     DIR_OUTPOINT,
     DIR_FPMETA,
     DIR_FPMETAS,
     DIR_OPTION,
     DIR_STREAM,
     DIR_EXSID,
     DIR_STMETA,
     DIR_STCODEC,
     DIR_STEDATA,
     DIR_CHAPTER,
  } ParseDirective;
  
  static const ParseSyntax syntax[] = {
      [DIR_FFCONCAT ] = { "ffconcat",             "kk",   0 },
      [DIR_FILE     ] = { "file",                 "s",    0 },
      [DIR_DURATION ] = { "duration",             "d",    NEEDS_FILE },
      [DIR_INPOINT  ] = { "inpoint",              "d",    NEEDS_FILE },
      [DIR_OUTPOINT ] = { "outpoint",             "d",    NEEDS_FILE },
      [DIR_FPMETA   ] = { "file_packet_meta",     "ks",   NEEDS_FILE },
      [DIR_FPMETAS  ] = { "file_packet_metadata", "s",    NEEDS_FILE },
      [DIR_OPTION   ] = { "option",               "ks",   NEEDS_FILE | NEEDS_UNSAFE },
      [DIR_STREAM   ] = { "stream",               "",     0 },
      [DIR_EXSID    ] = { "exact_stream_id",      "i",    NEEDS_STREAM },
      [DIR_STMETA   ] = { "stream_meta",          "ks",   NEEDS_STREAM },
      [DIR_STCODEC  ] = { "stream_codec",         "k",    NEEDS_STREAM },
      [DIR_STEDATA  ] = { "stream_extradata",     "k",    NEEDS_STREAM },
      [DIR_CHAPTER  ] = { "chapter",              "idd",  0 },
  };
  
  static int concat_parse_script(AVFormatContext *avf)
  {
      ConcatContext *cat = avf->priv_data;
      unsigned nb_files_alloc = 0;
      AVBPrint bp;
      uint8_t *cursor, *keyword;
      ConcatFile *file = NULL;
      AVStream *stream = NULL;
      AVChapter *chapter = NULL;
      unsigned line = 0, arg;
      const ParseSyntax *dir;
      char *arg_kw[MAX_ARGS];
      char *arg_str[MAX_ARGS] = { 0 };
      int64_t arg_int[MAX_ARGS];
      int ret;
  
      av_bprint_init(&bp, 0, AV_BPRINT_SIZE_UNLIMITED);
  
      while ((ret = ff_read_line_to_bprint_overwrite(avf->pb, &bp)) >= 0) {
          line++;
          cursor = bp.str;
          keyword = get_keyword(&cursor);
          if (!*keyword || *keyword == '#')
              continue;
          for (dir = syntax; dir < syntax + FF_ARRAY_ELEMS(syntax); dir++)
              if (!strcmp(dir->keyword, keyword))
                  break;
          if (dir >= syntax + FF_ARRAY_ELEMS(syntax)) {
              av_log(avf, AV_LOG_ERROR, "Line %d: unknown keyword '%s'\n",
                     line, keyword);
              FAIL(AVERROR_INVALIDDATA);
          }
  
          /* Flags check */
          if ((dir->flags & NEEDS_UNSAFE) && cat->safe) {
              av_log(avf, AV_LOG_ERROR, "Line %d: %s not allowed if safe\n", line, keyword);
              FAIL(AVERROR_INVALIDDATA);
          }
          if ((dir->flags & NEEDS_FILE) && !cat->nb_files) {
              av_log(avf, AV_LOG_ERROR, "Line %d: %s without file\n", line, keyword);
              FAIL(AVERROR_INVALIDDATA);
          }
          if ((dir->flags & NEEDS_STREAM) && !avf->nb_streams) {
              av_log(avf, AV_LOG_ERROR, "Line %d: %s without stream\n", line, keyword);
              FAIL(AVERROR_INVALIDDATA);
          }
  
          /* Arguments parsing */
          for (arg = 0; arg < FF_ARRAY_ELEMS(dir->args) && dir->args[arg]; arg++) {
              switch (dir->args[arg]) {
              case 'd': /* duration */
                  arg_kw[arg] = get_keyword(&cursor);
                  ret = av_parse_time(&arg_int[arg], arg_kw[arg], 1);
                  if (ret < 0) {
                      av_log(avf, AV_LOG_ERROR, "Line %d: invalid duration '%s'\n",
                             line, arg_kw[arg]);
                      goto fail;
                  }
                  break;
              case 'i': /* integer */
                  arg_int[arg] = strtol(get_keyword(&cursor), NULL, 0);
                  break;
              case 'k': /* keyword */
                  arg_kw[arg] = get_keyword(&cursor);
                  break;
              case 's': /* string */
                  av_assert0(!arg_str[arg]);
                  arg_str[arg] = av_get_token((const char **)&cursor, SPACE_CHARS);
                  if (!arg_str[arg])
                      FAIL(AVERROR(ENOMEM));
                  if (!*arg_str[arg]) {
                      av_log(avf, AV_LOG_ERROR, "Line %d: string required\n", line);
                      FAIL(AVERROR_INVALIDDATA);
                  }
                  break;
              default:
                  FAIL(AVERROR_BUG);
              }
          }
  
          /* Directive action */
          switch ((ParseDirective)(dir - syntax)) {
  
          case DIR_FFCONCAT:
              if (strcmp(arg_kw[0], "version") || strcmp(arg_kw[1], "1.0")) {
                  av_log(avf, AV_LOG_ERROR, "Line %d: invalid version\n", line);
                  FAIL(AVERROR_INVALIDDATA);
              }
              break;
  
          case DIR_FILE:
              ret = add_file(avf, arg_str[0], &file, &nb_files_alloc);
              arg_str[0] = NULL;
              if (ret < 0)
                  goto fail;
              break;
  
          case DIR_DURATION:
              file->user_duration = arg_int[0];
              break;
  
          case DIR_INPOINT:
              file->inpoint = arg_int[0];
              break;
  
          case DIR_OUTPOINT:
              file->outpoint = arg_int[0];
              break;
  
          case DIR_FPMETA:
              ret = av_dict_set(&file->metadata, arg_kw[0], arg_str[1], AV_DICT_DONT_STRDUP_VAL);
              arg_str[1] = NULL;
              if (ret < 0)
                  FAIL(ret);
              break;
  
          case DIR_FPMETAS:
              if ((ret = av_dict_parse_string(&file->metadata, arg_str[0], "=", "", 0)) < 0) {
                  av_log(avf, AV_LOG_ERROR, "Line %d: failed to parse metadata string\n", line);
                  FAIL(AVERROR_INVALIDDATA);
              }
              av_log(avf, AV_LOG_WARNING,
                     "'file_packet_metadata key=value:key=value' is deprecated, "
                     "use multiple 'file_packet_meta key value' instead\n");
              av_freep(&arg_str[0]);
              break;
  
          case DIR_OPTION:
              ret = av_dict_set(&file->options, arg_kw[0], arg_str[1], AV_DICT_DONT_STRDUP_VAL);
              arg_str[1] = NULL;
              if (ret < 0)
                  FAIL(ret);
              break;
  
          case DIR_STREAM:
              stream = avformat_new_stream(avf, NULL);
              if (!stream)
                  FAIL(AVERROR(ENOMEM));
              break;
  
          case DIR_EXSID:
              stream->id = arg_int[0];
              break;
          case DIR_STMETA:
              ret = av_dict_set(&stream->metadata, arg_kw[0], arg_str[1], AV_DICT_DONT_STRDUP_VAL);
              arg_str[1] = NULL;
              if (ret < 0)
                  FAIL(ret);
              break;
  
          case DIR_STCODEC: {
              const AVCodecDescriptor *codec = avcodec_descriptor_get_by_name(arg_kw[0]);
              if (!codec) {
                  av_log(avf, AV_LOG_ERROR, "Line %d: codec '%s' not found\n", line, arg_kw[0]);
                  FAIL(AVERROR_DECODER_NOT_FOUND);
              }
              stream->codecpar->codec_type = codec->type;
              stream->codecpar->codec_id = codec->id;
              break;
          }
  
          case DIR_STEDATA: {
              int size = ff_hex_to_data(NULL, arg_kw[0]);
              ret = ff_alloc_extradata(stream->codecpar, size);
              if (ret < 0)
                  FAIL(ret);
              ff_hex_to_data(stream->codecpar->extradata, arg_kw[0]);
              break;
          }
  
          case DIR_CHAPTER:
              chapter = avpriv_new_chapter(avf, arg_int[0], AV_TIME_BASE_Q,
                                           arg_int[1], arg_int[2], NULL);
              if (!chapter)
                  FAIL(ENOMEM);
              break;
  
          default:
              FAIL(AVERROR_BUG);
          }
      }
  
  fail:
      for (arg = 0; arg < MAX_ARGS; arg++)
          av_freep(&arg_str[arg]);
      av_bprint_finalize(&bp, NULL);
      return ret == AVERROR_EOF ? 0 : ret;
  }
  
  static int concat_read_header(AVFormatContext *avf)
  {
      ConcatContext *cat = avf->priv_data;
      int64_t time = 0;
      unsigned i;
      int ret;
  
      ret = concat_parse_script(avf);
      if (ret < 0)
          return ret;
      if (!cat->nb_files) {
          av_log(avf, AV_LOG_ERROR, "No files to concat\n");
          return AVERROR_INVALIDDATA;
      }
  
      for (i = 0; i < cat->nb_files; i++) {
          if (cat->files[i].start_time == AV_NOPTS_VALUE)
              cat->files[i].start_time = time;
          else
              time = cat->files[i].start_time;
          if (cat->files[i].user_duration == AV_NOPTS_VALUE) {
              if (cat->files[i].inpoint == AV_NOPTS_VALUE || cat->files[i].outpoint == AV_NOPTS_VALUE)
                  break;
              cat->files[i].user_duration = cat->files[i].outpoint - cat->files[i].inpoint;
          }
          cat->files[i].duration = cat->files[i].user_duration;
          time += cat->files[i].user_duration;
      }
      if (i == cat->nb_files) {
          avf->duration = time;
          cat->seekable = 1;
      }
  
      cat->stream_match_mode = avf->nb_streams ? MATCH_EXACT_ID :
                                                 MATCH_ONE_TO_ONE;
      if ((ret = open_file(avf, 0)) < 0)
          return ret;
  
      return 0;
  }
  
  static int open_next_file(AVFormatContext *avf)
  {
      ConcatContext *cat = avf->priv_data;
      unsigned fileno = cat->cur_file - cat->files;
  
      cat->cur_file->duration = get_best_effort_duration(cat->cur_file, cat->avf);
  
      if (++fileno >= cat->nb_files) {
          cat->eof = 1;
          return AVERROR_EOF;
      }
      return open_file(avf, fileno);
  }
  
  static int filter_packet(AVFormatContext *avf, ConcatStream *cs, AVPacket *pkt)
  {
      int ret;
  
      if (cs->bsf) {
          ret = av_bsf_send_packet(cs->bsf, pkt);
          if (ret < 0) {
              av_log(avf, AV_LOG_ERROR, "h264_mp4toannexb filter "
                     "failed to send input packet\n");
              return ret;
          }
  
          while (!ret)
              ret = av_bsf_receive_packet(cs->bsf, pkt);
  
          if (ret < 0 && (ret != AVERROR(EAGAIN) && ret != AVERROR_EOF)) {
              av_log(avf, AV_LOG_ERROR, "h264_mp4toannexb filter "
                     "failed to receive output packet\n");
              return ret;
          }
      }
      return 0;
  }
  
  /* Returns true if the packet dts is greater or equal to the specified outpoint. */
  static int packet_after_outpoint(ConcatContext *cat, AVPacket *pkt)
  {
      if (cat->cur_file->outpoint != AV_NOPTS_VALUE && pkt->dts != AV_NOPTS_VALUE) {
          return av_compare_ts(pkt->dts, cat->avf->streams[pkt->stream_index]->time_base,
                               cat->cur_file->outpoint, AV_TIME_BASE_Q) >= 0;
      }
      return 0;
  }
  
  static int concat_read_packet(AVFormatContext *avf, AVPacket *pkt)
  {
      ConcatContext *cat = avf->priv_data;
      int ret;
      int64_t delta;
      ConcatStream *cs;
      AVStream *st;
      FFStream *sti;
  
      if (cat->eof)
          return AVERROR_EOF;
  
      if (!cat->avf)
          return AVERROR(EIO);
  
      while (1) {
          ret = av_read_frame(cat->avf, pkt);
          if (ret == AVERROR_EOF) {
              if ((ret = open_next_file(avf)) < 0)
                  return ret;
              continue;
          }
          if (ret < 0)
              return ret;
          if ((ret = match_streams(avf)) < 0) {
              return ret;
          }
          if (packet_after_outpoint(cat, pkt)) {
              av_packet_unref(pkt);
              if ((ret = open_next_file(avf)) < 0)
                  return ret;
              continue;
          }
          cs = &cat->cur_file->streams[pkt->stream_index];
          if (cs->out_stream_index < 0) {
              av_packet_unref(pkt);
              continue;
          }
          break;
      }
      if ((ret = filter_packet(avf, cs, pkt)) < 0)
          return ret;
  
      st = cat->avf->streams[pkt->stream_index];
      sti = ffstream(st);
      av_log(avf, AV_LOG_DEBUG, "file:%d stream:%d pts:%s pts_time:%s dts:%s dts_time:%s",
             (unsigned)(cat->cur_file - cat->files), pkt->stream_index,
             av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, &st->time_base),
             av_ts2str(pkt->dts), av_ts2timestr(pkt->dts, &st->time_base));
  
      delta = av_rescale_q(cat->cur_file->start_time - cat->cur_file->file_inpoint,
                           AV_TIME_BASE_Q,
                           cat->avf->streams[pkt->stream_index]->time_base);
      if (pkt->pts != AV_NOPTS_VALUE)
          pkt->pts += delta;
      if (pkt->dts != AV_NOPTS_VALUE)
          pkt->dts += delta;
      av_log(avf, AV_LOG_DEBUG, " -> pts:%s pts_time:%s dts:%s dts_time:%s\n",
             av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, &st->time_base),
             av_ts2str(pkt->dts), av_ts2timestr(pkt->dts, &st->time_base));
      if (cat->cur_file->metadata) {
          size_t metadata_len;
          char* packed_metadata = av_packet_pack_dictionary(cat->cur_file->metadata, &metadata_len);
          if (!packed_metadata)
              return AVERROR(ENOMEM);
          ret = av_packet_add_side_data(pkt, AV_PKT_DATA_STRINGS_METADATA,
                                        packed_metadata, metadata_len);
          if (ret < 0) {
              av_freep(&packed_metadata);
              return ret;
          }
      }
  
      if (cat->cur_file->duration == AV_NOPTS_VALUE && sti->cur_dts != AV_NOPTS_VALUE) {
          int64_t next_dts = av_rescale_q(sti->cur_dts, st->time_base, AV_TIME_BASE_Q);
          if (cat->cur_file->next_dts == AV_NOPTS_VALUE || next_dts > cat->cur_file->next_dts) {
              cat->cur_file->next_dts = next_dts;
          }
      }
  
      pkt->stream_index = cs->out_stream_index;
      return 0;
  }
  
  static void rescale_interval(AVRational tb_in, AVRational tb_out,
                               int64_t *min_ts, int64_t *ts, int64_t *max_ts)
  {
      *ts     = av_rescale_q    (*    ts, tb_in, tb_out);
      *min_ts = av_rescale_q_rnd(*min_ts, tb_in, tb_out,
                                 AV_ROUND_UP   | AV_ROUND_PASS_MINMAX);
      *max_ts = av_rescale_q_rnd(*max_ts, tb_in, tb_out,
                                 AV_ROUND_DOWN | AV_ROUND_PASS_MINMAX);
  }
  
  static int try_seek(AVFormatContext *avf, int stream,
                      int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
  {
      ConcatContext *cat = avf->priv_data;
      int64_t t0 = cat->cur_file->start_time - cat->cur_file->file_inpoint;
  
      ts -= t0;
      min_ts = min_ts == INT64_MIN ? INT64_MIN : min_ts - t0;
      max_ts = max_ts == INT64_MAX ? INT64_MAX : max_ts - t0;
      if (stream >= 0) {
          if (stream >= cat->avf->nb_streams)
              return AVERROR(EIO);
          rescale_interval(AV_TIME_BASE_Q, cat->avf->streams[stream]->time_base,
                           &min_ts, &ts, &max_ts);
      }
      return avformat_seek_file(cat->avf, stream, min_ts, ts, max_ts, flags);
  }
  
  static int real_seek(AVFormatContext *avf, int stream,
                       int64_t min_ts, int64_t ts, int64_t max_ts, int flags, AVFormatContext *cur_avf)
  {
      ConcatContext *cat = avf->priv_data;
      int ret, left, right;
  
      if (stream >= 0) {
          if (stream >= avf->nb_streams)
              return AVERROR(EINVAL);
          rescale_interval(avf->streams[stream]->time_base, AV_TIME_BASE_Q,
                           &min_ts, &ts, &max_ts);
      }
  
      left  = 0;
      right = cat->nb_files;
  
      /* Always support seek to start */
      if (ts <= 0)
          right = 1;
      else if (!cat->seekable)
          return AVERROR(ESPIPE); /* XXX: can we use it? */
  
      while (right - left > 1) {
          int mid = (left + right) / 2;
          if (ts < cat->files[mid].start_time)
              right = mid;
          else
              left  = mid;
      }
  
      if (cat->cur_file != &cat->files[left]) {
          if ((ret = open_file(avf, left)) < 0)
              return ret;
      } else {
          cat->avf = cur_avf;
      }
  
      ret = try_seek(avf, stream, min_ts, ts, max_ts, flags);
      if (ret < 0 &&
          left < cat->nb_files - 1 &&
          cat->files[left + 1].start_time < max_ts) {
          if (cat->cur_file == &cat->files[left])
              cat->avf = NULL;
          if ((ret = open_file(avf, left + 1)) < 0)
              return ret;
          ret = try_seek(avf, stream, min_ts, ts, max_ts, flags);
      }
      return ret;
  }
  
  static int concat_seek(AVFormatContext *avf, int stream,
                         int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
  {
      ConcatContext *cat = avf->priv_data;
      ConcatFile *cur_file_saved = cat->cur_file;
      AVFormatContext *cur_avf_saved = cat->avf;
      int ret;
  
      if (flags & (AVSEEK_FLAG_BYTE | AVSEEK_FLAG_FRAME))
          return AVERROR(ENOSYS);
      cat->avf = NULL;
      if ((ret = real_seek(avf, stream, min_ts, ts, max_ts, flags, cur_avf_saved)) < 0) {
          if (cat->cur_file != cur_file_saved) {
              if (cat->avf)
                  avformat_close_input(&cat->avf);
          }
          cat->avf      = cur_avf_saved;
          cat->cur_file = cur_file_saved;
      } else {
          if (cat->cur_file != cur_file_saved) {
              avformat_close_input(&cur_avf_saved);
          }
          cat->eof = 0;
      }
      return ret;
  }
  
  #define OFFSET(x) offsetof(ConcatContext, x)
  #define DEC AV_OPT_FLAG_DECODING_PARAM
  
  static const AVOption options[] = {
      { "safe", "enable safe mode",
        OFFSET(safe), AV_OPT_TYPE_BOOL, {.i64 = 1}, 0, 1, DEC },
      { "auto_convert", "automatically convert bitstream format",
        OFFSET(auto_convert), AV_OPT_TYPE_BOOL, {.i64 = 1}, 0, 1, DEC },
      { "segment_time_metadata", "output file segment start time and duration as packet metadata",
        OFFSET(segment_time_metadata), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, DEC },
      { NULL }
  };
  
  static const AVClass concat_class = {
      .class_name = "concat demuxer",
      .item_name  = av_default_item_name,
      .option     = options,
      .version    = LIBAVUTIL_VERSION_INT,
  };
  
  
  const AVInputFormat ff_concat_demuxer = {
      .name           = "concat",
      .long_name      = NULL_IF_CONFIG_SMALL("Virtual concatenation script"),
      .priv_data_size = sizeof(ConcatContext),
      .flags_internal = FF_FMT_INIT_CLEANUP,
      .read_probe     = concat_probe,
      .read_header    = concat_read_header,
      .read_packet    = concat_read_packet,
      .read_close     = concat_read_close,
      .read_seek2     = concat_seek,
      .priv_class     = &concat_class,
  };
  