text: /*
   * "NUT" Container Format demuxer
   * Copyright (c) 2004-2006 Michael Niedermayer
   * Copyright (c) 2003 Alex Beregszaszi
   *
   * 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/bswap.h"
  #include "libavutil/dict.h"
  #include "libavutil/intreadwrite.h"
  #include "libavutil/mathematics.h"
  #include "libavutil/tree.h"
  #include "libavcodec/bytestream.h"
  #include "avio_internal.h"
  #include "isom.h"
  #include "nut.h"
  #include "riff.h"
  
  #define NUT_MAX_STREAMS 256    /* arbitrary sanity check value */
  
  static int64_t nut_read_timestamp(AVFormatContext *s, int stream_index,
                                    int64_t *pos_arg, int64_t pos_limit);
  
  static int get_str(AVIOContext *bc, char *string, unsigned int maxlen)
  {
      unsigned int len = ffio_read_varlen(bc);
  
      if (len && maxlen)
          avio_read(bc, string, FFMIN(len, maxlen));
      while (len > maxlen) {
          avio_r8(bc);
          len--;
          if (bc->eof_reached)
              len = maxlen;
      }
  
      if (maxlen)
          string[FFMIN(len, maxlen - 1)] = 0;
  
      if (bc->eof_reached)
          return AVERROR_EOF;
      if (maxlen == len)
          return -1;
      else
          return 0;
  }
  
  static int64_t get_s(AVIOContext *bc)
  {
      int64_t v = ffio_read_varlen(bc) + 1;
  
      if (v & 1)
          return -(v >> 1);
      else
          return  (v >> 1);
  }
  
  static uint64_t get_fourcc(AVIOContext *bc)
  {
      unsigned int len = ffio_read_varlen(bc);
  
      if (len == 2)
          return avio_rl16(bc);
      else if (len == 4)
          return avio_rl32(bc);
      else {
          av_log(NULL, AV_LOG_ERROR, "Unsupported fourcc length %d\n", len);
          return -1;
      }
  }
  
  static int get_packetheader(NUTContext *nut, AVIOContext *bc,
                              int calculate_checksum, uint64_t startcode)
  {
      int64_t size;
  
      startcode = av_be2ne64(startcode);
      startcode = ff_crc04C11DB7_update(0, (uint8_t*) &startcode, 8);
  
      ffio_init_checksum(bc, ff_crc04C11DB7_update, startcode);
      size = ffio_read_varlen(bc);
      if (size > 4096)
          avio_rb32(bc);
      if (ffio_get_checksum(bc) && size > 4096)
          return -1;
  
      ffio_init_checksum(bc, calculate_checksum ? ff_crc04C11DB7_update : NULL, 0);
  
      return size;
  }
  
  static uint64_t find_any_startcode(AVIOContext *bc, int64_t pos)
  {
      uint64_t state = 0;
  
      if (pos >= 0)
          /* Note, this may fail if the stream is not seekable, but that should
           * not matter, as in this case we simply start where we currently are */
          avio_seek(bc, pos, SEEK_SET);
      while (!avio_feof(bc)) {
          state = (state << 8) | avio_r8(bc);
          if ((state >> 56) != 'N')
              continue;
          switch (state) {
          case MAIN_STARTCODE:
          case STREAM_STARTCODE:
          case SYNCPOINT_STARTCODE:
          case INFO_STARTCODE:
          case INDEX_STARTCODE:
              return state;
          }
      }
  
      return 0;
  }
  
  /**
   * Find the given startcode.
   * @param code the startcode
   * @param pos the start position of the search, or -1 if the current position
   * @return the position of the startcode or -1 if not found
   */
  static int64_t find_startcode(AVIOContext *bc, uint64_t code, int64_t pos)
  {
      for (;;) {
          uint64_t startcode = find_any_startcode(bc, pos);
          if (startcode == code)
              return avio_tell(bc) - 8;
          else if (startcode == 0)
              return -1;
          pos = -1;
      }
  }
  
  static int nut_probe(const AVProbeData *p)
  {
      int i;
  
      for (i = 0; i < p->buf_size-8; i++) {
          if (AV_RB32(p->buf+i) != MAIN_STARTCODE>>32)
              continue;
          if (AV_RB32(p->buf+i+4) == (MAIN_STARTCODE & 0xFFFFFFFF))
              return AVPROBE_SCORE_MAX;
      }
      return 0;
  }
  
  #define GET_V(dst, check)                                                     \
      do {                                                                      \
          tmp = ffio_read_varlen(bc);                                           \
          if (!(check)) {                                                       \
              av_log(s, AV_LOG_ERROR, "Error " #dst " is (%"PRId64")\n", tmp);  \
              ret = AVERROR_INVALIDDATA;                                        \
              goto fail;                                                        \
          }                                                                     \
          dst = tmp;                                                            \
      } while (0)
  
  static int skip_reserved(AVIOContext *bc, int64_t pos)
  {
      pos -= avio_tell(bc);
      if (pos < 0) {
          avio_seek(bc, pos, SEEK_CUR);
          return AVERROR_INVALIDDATA;
      } else {
          while (pos--) {
              if (bc->eof_reached)
                  return AVERROR_INVALIDDATA;
              avio_r8(bc);
          }
          return 0;
      }
  }
  
  static int decode_main_header(NUTContext *nut)
  {
      AVFormatContext *s = nut->avf;
      AVIOContext *bc    = s->pb;
      uint64_t tmp, end, length;
      unsigned int stream_count;
      int i, j, count, ret;
      int tmp_stream, tmp_mul, tmp_pts, tmp_size, tmp_res, tmp_head_idx;
  
      length = get_packetheader(nut, bc, 1, MAIN_STARTCODE);
      end = length + avio_tell(bc);
  
      nut->version = ffio_read_varlen(bc);
      if (nut->version < NUT_MIN_VERSION ||
          nut->version > NUT_MAX_VERSION) {
          av_log(s, AV_LOG_ERROR, "Version %d not supported.\n",
                 nut->version);
          return AVERROR(ENOSYS);
      }
      if (nut->version > 3)
          nut->minor_version = ffio_read_varlen(bc);
  
      GET_V(stream_count, tmp > 0 && tmp <= NUT_MAX_STREAMS);
  
      nut->max_distance = ffio_read_varlen(bc);
      if (nut->max_distance > 65536) {
          av_log(s, AV_LOG_DEBUG, "max_distance %d\n", nut->max_distance);
          nut->max_distance = 65536;
      }
  
      GET_V(nut->time_base_count, tmp > 0 && tmp < INT_MAX / sizeof(AVRational) && tmp < length/2);
      nut->time_base = av_malloc_array(nut->time_base_count, sizeof(AVRational));
      if (!nut->time_base)
          return AVERROR(ENOMEM);
  
      for (i = 0; i < nut->time_base_count; i++) {
          GET_V(nut->time_base[i].num, tmp > 0 && tmp < (1ULL << 31));
          GET_V(nut->time_base[i].den, tmp > 0 && tmp < (1ULL << 31));
          if (av_gcd(nut->time_base[i].num, nut->time_base[i].den) != 1) {
              av_log(s, AV_LOG_ERROR, "invalid time base %d/%d\n",
                     nut->time_base[i].num,
                     nut->time_base[i].den);
              ret = AVERROR_INVALIDDATA;
              goto fail;
          }
      }
      tmp_pts      = 0;
      tmp_mul      = 1;
      tmp_stream   = 0;
      tmp_head_idx = 0;
      for (i = 0; i < 256;) {
          int tmp_flags  = ffio_read_varlen(bc);
          int tmp_fields = ffio_read_varlen(bc);
  
          if (tmp_fields > 0)
              tmp_pts = get_s(bc);
          if (tmp_fields > 1)
              tmp_mul = ffio_read_varlen(bc);
          if (tmp_fields > 2)
              tmp_stream = ffio_read_varlen(bc);
          if (tmp_fields > 3)
              tmp_size = ffio_read_varlen(bc);
          else
              tmp_size = 0;
          if (tmp_fields > 4)
              tmp_res = ffio_read_varlen(bc);
          else
              tmp_res = 0;
          if (tmp_fields > 5)
              count = ffio_read_varlen(bc);
          else
              count = tmp_mul - (unsigned)tmp_size;
          if (tmp_fields > 6)
              get_s(bc);
          if (tmp_fields > 7)
              tmp_head_idx = ffio_read_varlen(bc);
  
          while (tmp_fields-- > 8) {
              if (bc->eof_reached) {
                  av_log(s, AV_LOG_ERROR, "reached EOF while decoding main header\n");
                  ret = AVERROR_INVALIDDATA;
                  goto fail;
              }
              ffio_read_varlen(bc);
          }
  
          if (count <= 0 || count > 256 - (i <= 'N') - i) {
              av_log(s, AV_LOG_ERROR, "illegal count %d at %d\n", count, i);
              ret = AVERROR_INVALIDDATA;
              goto fail;
          }
          if (tmp_stream >= stream_count) {
              av_log(s, AV_LOG_ERROR, "illegal stream number %d >= %d\n",
                     tmp_stream, stream_count);
              ret = AVERROR_INVALIDDATA;
              goto fail;
          }
  
          for (j = 0; j < count; j++, i++) {
              if (i == 'N') {
                  nut->frame_code[i].flags = FLAG_INVALID;
                  j--;
                  continue;
              }
              nut->frame_code[i].flags          = tmp_flags;
              nut->frame_code[i].pts_delta      = tmp_pts;
              nut->frame_code[i].stream_id      = tmp_stream;
              nut->frame_code[i].size_mul       = tmp_mul;
              nut->frame_code[i].size_lsb       = tmp_size + j;
              nut->frame_code[i].reserved_count = tmp_res;
              nut->frame_code[i].header_idx     = tmp_head_idx;
          }
      }
      av_assert0(nut->frame_code['N'].flags == FLAG_INVALID);
  
      if (end > avio_tell(bc) + 4) {
          int rem = 1024;
          GET_V(nut->header_count, tmp < 128U);
          nut->header_count++;
          for (i = 1; i < nut->header_count; i++) {
              uint8_t *hdr;
              GET_V(nut->header_len[i], tmp > 0 && tmp < 256);
              if (rem < nut->header_len[i]) {
                  av_log(s, AV_LOG_ERROR,
                         "invalid elision header %d : %d > %d\n",
                         i, nut->header_len[i], rem);
                  ret = AVERROR_INVALIDDATA;
                  goto fail;
              }
              rem -= nut->header_len[i];
              hdr = av_malloc(nut->header_len[i]);
              if (!hdr) {
                  ret = AVERROR(ENOMEM);
                  goto fail;
              }
              avio_read(bc, hdr, nut->header_len[i]);
              nut->header[i] = hdr;
          }
          av_assert0(nut->header_len[0] == 0);
      }
  
      // flags had been effectively introduced in version 4
      if (nut->version > 3 && end > avio_tell(bc) + 4) {
          nut->flags = ffio_read_varlen(bc);
      }
  
      if (skip_reserved(bc, end) || ffio_get_checksum(bc)) {
          av_log(s, AV_LOG_ERROR, "main header checksum mismatch\n");
          ret = AVERROR_INVALIDDATA;
          goto fail;
      }
  
      nut->stream = av_calloc(stream_count, sizeof(StreamContext));
      if (!nut->stream) {
          ret = AVERROR(ENOMEM);
          goto fail;
      }
      for (i = 0; i < stream_count; i++)
          avformat_new_stream(s, NULL);
  
      return 0;
  fail:
      av_freep(&nut->time_base);
      for (i = 1; i < nut->header_count; i++) {
          av_freep(&nut->header[i]);
      }
      nut->header_count = 0;
      return ret;
  }
  
  static int decode_stream_header(NUTContext *nut)
  {
      AVFormatContext *s = nut->avf;
      AVIOContext *bc    = s->pb;
      StreamContext *stc;
      int class, stream_id, ret;
      uint64_t tmp, end;
      AVStream *st = NULL;
  
      end  = get_packetheader(nut, bc, 1, STREAM_STARTCODE);
      end += avio_tell(bc);
  
      GET_V(stream_id, tmp < s->nb_streams && !nut->stream[tmp].time_base);
      stc = &nut->stream[stream_id];
      st  = s->streams[stream_id];
      if (!st)
          return AVERROR(ENOMEM);
  
      class                = ffio_read_varlen(bc);
      tmp                  = get_fourcc(bc);
      st->codecpar->codec_tag = tmp;
      switch (class) {
      case 0:
          st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
          st->codecpar->codec_id   = av_codec_get_id((const AVCodecTag * const []) {
                                                      ff_nut_video_tags,
                                                      ff_codec_bmp_tags,
                                                      ff_codec_movvideo_tags,
                                                      0
                                                  },
                                                  tmp);
          break;
      case 1:
          st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
          st->codecpar->codec_id   = av_codec_get_id((const AVCodecTag * const []) {
                                                      ff_nut_audio_tags,
                                                      ff_codec_wav_tags,
                                                      ff_nut_audio_extra_tags,
                                                      0
                                                  },
                                                  tmp);
          break;
      case 2:
          st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
          st->codecpar->codec_id   = ff_codec_get_id(ff_nut_subtitle_tags, tmp);
          break;
      case 3:
          st->codecpar->codec_type = AVMEDIA_TYPE_DATA;
          st->codecpar->codec_id   = ff_codec_get_id(ff_nut_data_tags, tmp);
          break;
      default:
          av_log(s, AV_LOG_ERROR, "unknown stream class (%d)\n", class);
          return AVERROR(ENOSYS);
      }
      if (class < 3 && st->codecpar->codec_id == AV_CODEC_ID_NONE)
          av_log(s, AV_LOG_ERROR,
                 "Unknown codec tag '0x%04x' for stream number %d\n",
                 (unsigned int) tmp, stream_id);
  
      GET_V(stc->time_base_id, tmp < nut->time_base_count);
      GET_V(stc->msb_pts_shift, tmp < 16);
      stc->max_pts_distance = ffio_read_varlen(bc);
      GET_V(stc->decode_delay, tmp < 1000); // sanity limit, raise this if Moore's law is true
      st->codecpar->video_delay = stc->decode_delay;
      ffio_read_varlen(bc); // stream flags
  
      GET_V(st->codecpar->extradata_size, tmp < (1 << 30));
      if (st->codecpar->extradata_size) {
          ret = ff_get_extradata(s, st->codecpar, bc,
                                 st->codecpar->extradata_size);
          if (ret < 0)
              return ret;
      }
  
      if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
          GET_V(st->codecpar->width,  tmp > 0);
          GET_V(st->codecpar->height, tmp > 0);
          st->sample_aspect_ratio.num = ffio_read_varlen(bc);
          st->sample_aspect_ratio.den = ffio_read_varlen(bc);
          if ((!st->sample_aspect_ratio.num) != (!st->sample_aspect_ratio.den)) {
              av_log(s, AV_LOG_ERROR, "invalid aspect ratio %d/%d\n",
                     st->sample_aspect_ratio.num, st->sample_aspect_ratio.den);
              ret = AVERROR_INVALIDDATA;
              goto fail;
          }
          ffio_read_varlen(bc); /* csp type */
      } else if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
          GET_V(st->codecpar->sample_rate, tmp > 0);
          ffio_read_varlen(bc); // samplerate_den
          GET_V(st->codecpar->channels, tmp > 0);
      }
      if (skip_reserved(bc, end) || ffio_get_checksum(bc)) {
          av_log(s, AV_LOG_ERROR,
                 "stream header %d checksum mismatch\n", stream_id);
          ret = AVERROR_INVALIDDATA;
          goto fail;
      }
      stc->time_base = &nut->time_base[stc->time_base_id];
      avpriv_set_pts_info(s->streams[stream_id], 63, stc->time_base->num,
                          stc->time_base->den);
      return 0;
  fail:
      if (st && st->codecpar) {
          av_freep(&st->codecpar->extradata);
          st->codecpar->extradata_size = 0;
      }
      return ret;
  }
  
  static void set_disposition_bits(AVFormatContext *avf, char *value,
                                   int stream_id)
  {
      int flag = 0, i;
  
      for (i = 0; ff_nut_dispositions[i].flag; ++i)
          if (!strcmp(ff_nut_dispositions[i].str, value))
              flag = ff_nut_dispositions[i].flag;
      if (!flag)
          av_log(avf, AV_LOG_INFO, "unknown disposition type '%s'\n", value);
      for (i = 0; i < avf->nb_streams; ++i)
          if (stream_id == i || stream_id == -1)
              avf->streams[i]->disposition |= flag;
  }
  
  static int decode_info_header(NUTContext *nut)
  {
      AVFormatContext *s = nut->avf;
      AVIOContext *bc    = s->pb;
      uint64_t tmp, chapter_start, chapter_len;
      unsigned int stream_id_plus1, count;
      int i, ret = 0;
      int64_t chapter_id, value, end;
      char name[256], str_value[1024], type_str[256];
      const char *type;
      int *event_flags        = NULL;
      AVChapter *chapter      = NULL;
      AVStream *st            = NULL;
      AVDictionary **metadata = NULL;
      int metadata_flag       = 0;
  
      end  = get_packetheader(nut, bc, 1, INFO_STARTCODE);
      end += avio_tell(bc);
  
      GET_V(stream_id_plus1, tmp <= s->nb_streams);
      chapter_id    = get_s(bc);
      chapter_start = ffio_read_varlen(bc);
      chapter_len   = ffio_read_varlen(bc);
      count         = ffio_read_varlen(bc);
  
      if (chapter_id && !stream_id_plus1) {
          int64_t start = chapter_start / nut->time_base_count;
          chapter = avpriv_new_chapter(s, chapter_id,
                                       nut->time_base[chapter_start %
                                                      nut->time_base_count],
                                       start, start + chapter_len, NULL);
          if (!chapter) {
              av_log(s, AV_LOG_ERROR, "Could not create chapter.\n");
              return AVERROR(ENOMEM);
          }
          metadata = &chapter->metadata;
      } else if (stream_id_plus1) {
          st       = s->streams[stream_id_plus1 - 1];
          metadata = &st->metadata;
          event_flags = &st->event_flags;
          metadata_flag = AVSTREAM_EVENT_FLAG_METADATA_UPDATED;
      } else {
          metadata = &s->metadata;
          event_flags = &s->event_flags;
          metadata_flag = AVFMT_EVENT_FLAG_METADATA_UPDATED;
      }
  
      for (i = 0; i < count; i++) {
          ret = get_str(bc, name, sizeof(name));
          if (ret < 0) {
              av_log(s, AV_LOG_ERROR, "get_str failed while decoding info header\n");
              return ret;
          }
          value = get_s(bc);
          str_value[0] = 0;
  
          if (value == -1) {
              type = "UTF-8";
              ret = get_str(bc, str_value, sizeof(str_value));
          } else if (value == -2) {
              ret = get_str(bc, type_str, sizeof(type_str));
              if (ret < 0) {
                  av_log(s, AV_LOG_ERROR, "get_str failed while decoding info header\n");
                  return ret;
              }
              type = type_str;
              ret = get_str(bc, str_value, sizeof(str_value));
          } else if (value == -3) {
              type  = "s";
              value = get_s(bc);
          } else if (value == -4) {
              type  = "t";
              value = ffio_read_varlen(bc);
          } else if (value < -4) {
              type = "r";
              get_s(bc);
          } else {
              type = "v";
          }
  
          if (ret < 0) {
              av_log(s, AV_LOG_ERROR, "get_str failed while decoding info header\n");
              return ret;
          }
  
          if (stream_id_plus1 > s->nb_streams) {
              av_log(s, AV_LOG_WARNING,
                     "invalid stream id %d for info packet\n",
                     stream_id_plus1);
              continue;
          }
  
          if (!strcmp(type, "UTF-8")) {
              if (chapter_id == 0 && !strcmp(name, "Disposition")) {
                  set_disposition_bits(s, str_value, stream_id_plus1 - 1);
                  continue;
              }
  
              if (stream_id_plus1 && !strcmp(name, "r_frame_rate")) {
                  sscanf(str_value, "%d/%d", &st->r_frame_rate.num, &st->r_frame_rate.den);
                  if (st->r_frame_rate.num >= 1000LL*st->r_frame_rate.den ||
                      st->r_frame_rate.num < 0 || st->r_frame_rate.den < 0)
                      st->r_frame_rate.num = st->r_frame_rate.den = 0;
                  continue;
              }
  
              if (metadata && av_strcasecmp(name, "Uses") &&
                  av_strcasecmp(name, "Depends") && av_strcasecmp(name, "Replaces")) {
                  if (event_flags)
                      *event_flags |= metadata_flag;
                  av_dict_set(metadata, name, str_value, 0);
              }
          }
      }
  
      if (skip_reserved(bc, end) || ffio_get_checksum(bc)) {
          av_log(s, AV_LOG_ERROR, "info header checksum mismatch\n");
          return AVERROR_INVALIDDATA;
      }
  fail:
      return FFMIN(ret, 0);
  }
  
  static int decode_syncpoint(NUTContext *nut, int64_t *ts, int64_t *back_ptr)
  {
      AVFormatContext *s = nut->avf;
      AVIOContext *bc    = s->pb;
      int64_t end;
      uint64_t tmp;
      int ret;
  
      nut->last_syncpoint_pos = avio_tell(bc) - 8;
  
      end  = get_packetheader(nut, bc, 1, SYNCPOINT_STARTCODE);
      end += avio_tell(bc);
  
      tmp       = ffio_read_varlen(bc);
      *back_ptr = nut->last_syncpoint_pos - 16 * ffio_read_varlen(bc);
      if (*back_ptr < 0)
          return AVERROR_INVALIDDATA;
  
      ff_nut_reset_ts(nut, nut->time_base[tmp % nut->time_base_count],
                      tmp / nut->time_base_count);
  
      if (nut->flags & NUT_BROADCAST) {
          tmp = ffio_read_varlen(bc);
          av_log(s, AV_LOG_VERBOSE, "Syncpoint wallclock %"PRId64"\n",
                 av_rescale_q(tmp / nut->time_base_count,
                              nut->time_base[tmp % nut->time_base_count],
                              AV_TIME_BASE_Q));
      }
  
      if (skip_reserved(bc, end) || ffio_get_checksum(bc)) {
          av_log(s, AV_LOG_ERROR, "sync point checksum mismatch\n");
          return AVERROR_INVALIDDATA;
      }
  
      *ts = tmp / nut->time_base_count *
            av_q2d(nut->time_base[tmp % nut->time_base_count]) * AV_TIME_BASE;
  
      if ((ret = ff_nut_add_sp(nut, nut->last_syncpoint_pos, *back_ptr, *ts)) < 0)
          return ret;
  
      return 0;
  }
  
  //FIXME calculate exactly, this is just a good approximation.
  static int64_t find_duration(NUTContext *nut, int64_t filesize)
  {
      AVFormatContext *s = nut->avf;
      int64_t duration = 0;
  
      ff_find_last_ts(s, -1, &duration, NULL, nut_read_timestamp);
  
      if(duration > 0)
          s->duration_estimation_method = AVFMT_DURATION_FROM_PTS;
      return duration;
  }
  
  static int find_and_decode_index(NUTContext *nut)
  {
      AVFormatContext *s = nut->avf;
      AVIOContext *bc    = s->pb;
      uint64_t tmp, end;
      int i, j, syncpoint_count;
      int64_t filesize = avio_size(bc);
      int64_t *syncpoints = NULL;
      uint64_t max_pts;
      int8_t *has_keyframe = NULL;
      int ret = AVERROR_INVALIDDATA;
  
      if(filesize <= 0)
          return -1;
  
      avio_seek(bc, filesize - 12, SEEK_SET);
      avio_seek(bc, filesize - avio_rb64(bc), SEEK_SET);
      if (avio_rb64(bc) != INDEX_STARTCODE) {
          av_log(s, AV_LOG_WARNING, "no index at the end\n");
  
          if(s->duration<=0)
              s->duration = find_duration(nut, filesize);
          return ret;
      }
  
      end  = get_packetheader(nut, bc, 1, INDEX_STARTCODE);
      end += avio_tell(bc);
  
      max_pts = ffio_read_varlen(bc);
      s->duration = av_rescale_q(max_pts / nut->time_base_count,
                                 nut->time_base[max_pts % nut->time_base_count],
                                 AV_TIME_BASE_Q);
      s->duration_estimation_method = AVFMT_DURATION_FROM_PTS;
  
      GET_V(syncpoint_count, tmp < INT_MAX / 8 && tmp > 0);
      syncpoints   = av_malloc_array(syncpoint_count, sizeof(int64_t));
      has_keyframe = av_malloc_array(syncpoint_count + 1, sizeof(int8_t));
      if (!syncpoints || !has_keyframe) {
          ret = AVERROR(ENOMEM);
          goto fail;
      }
      for (i = 0; i < syncpoint_count; i++) {
          syncpoints[i] = ffio_read_varlen(bc);
          if (syncpoints[i] <= 0)
              goto fail;
          if (i)
              syncpoints[i] += syncpoints[i - 1];
      }
  
      for (i = 0; i < s->nb_streams; i++) {
          int64_t last_pts = -1;
          for (j = 0; j < syncpoint_count;) {
              uint64_t x = ffio_read_varlen(bc);
              int type   = x & 1;
              int n      = j;
              x >>= 1;
              if (type) {
                  int flag = x & 1;
                  x >>= 1;
                  if (n + x >= syncpoint_count + 1) {
                      av_log(s, AV_LOG_ERROR, "index overflow A %d + %"PRIu64" >= %d\n", n, x, syncpoint_count + 1);
                      goto fail;
                  }
                  while (x--)
                      has_keyframe[n++] = flag;
                  has_keyframe[n++] = !flag;
              } else {
                  if (x <= 1) {
                      av_log(s, AV_LOG_ERROR, "index: x %"PRIu64" is invalid\n", x);
                      goto fail;
                  }
                  while (x != 1) {
                      if (n >= syncpoint_count + 1) {
                          av_log(s, AV_LOG_ERROR, "index overflow B\n");
                          goto fail;
                      }
                      has_keyframe[n++] = x & 1;
                      x >>= 1;
                  }
              }
              if (has_keyframe[0]) {
                  av_log(s, AV_LOG_ERROR, "keyframe before first syncpoint in index\n");
                  goto fail;
              }
              av_assert0(n <= syncpoint_count + 1);
              for (; j < n && j < syncpoint_count; j++) {
                  if (has_keyframe[j]) {
                      uint64_t B, A = ffio_read_varlen(bc);
                      if (!A) {
                          A = ffio_read_varlen(bc);
                          B = ffio_read_varlen(bc);
                          // eor_pts[j][i] = last_pts + A + B
                      } else
                          B = 0;
                      av_add_index_entry(s->streams[i], 16 * syncpoints[j - 1],
                                         last_pts + A, 0, 0, AVINDEX_KEYFRAME);
                      last_pts += A + B;
                  }
              }
          }
      }
  
      if (skip_reserved(bc, end) || ffio_get_checksum(bc)) {
          av_log(s, AV_LOG_ERROR, "index checksum mismatch\n");
          goto fail;
      }
      ret = 0;
  
  fail:
      av_free(syncpoints);
      av_free(has_keyframe);
      return ret;
  }
  
  static int nut_read_close(AVFormatContext *s)
  {
      NUTContext *nut = s->priv_data;
      int i;
  
      av_freep(&nut->time_base);
      av_freep(&nut->stream);
      ff_nut_free_sp(nut);
      for (i = 1; i < nut->header_count; i++)
          av_freep(&nut->header[i]);
  
      return 0;
  }
  
  static int nut_read_header(AVFormatContext *s)
  {
      NUTContext *nut = s->priv_data;
      AVIOContext *bc = s->pb;
      int64_t pos;
      int initialized_stream_count;
  
      nut->avf = s;
  
      /* main header */
      pos = 0;
      do {
          pos = find_startcode(bc, MAIN_STARTCODE, pos) + 1;
          if (pos < 0 + 1) {
              av_log(s, AV_LOG_ERROR, "No main startcode found.\n");
              goto fail;
          }
      } while (decode_main_header(nut) < 0);
  
      /* stream headers */
      pos = 0;
      for (initialized_stream_count = 0; initialized_stream_count < s->nb_streams;) {
          pos = find_startcode(bc, STREAM_STARTCODE, pos) + 1;
          if (pos < 0 + 1) {
              av_log(s, AV_LOG_ERROR, "Not all stream headers found.\n");
              goto fail;
          }
          if (decode_stream_header(nut) >= 0)
              initialized_stream_count++;
      }
  
      /* info headers */
      pos = 0;
      for (;;) {
          uint64_t startcode = find_any_startcode(bc, pos);
          pos = avio_tell(bc);
  
          if (startcode == 0) {
              av_log(s, AV_LOG_ERROR, "EOF before video frames\n");
              goto fail;
          } else if (startcode == SYNCPOINT_STARTCODE) {
              nut->next_startcode = startcode;
              break;
          } else if (startcode != INFO_STARTCODE) {
              continue;
          }
  
          decode_info_header(nut);
      }
  
      s->internal->data_offset = pos - 8;
  
      if (bc->seekable & AVIO_SEEKABLE_NORMAL) {
          int64_t orig_pos = avio_tell(bc);
          find_and_decode_index(nut);
          avio_seek(bc, orig_pos, SEEK_SET);
      }
      av_assert0(nut->next_startcode == SYNCPOINT_STARTCODE);
  
      ff_metadata_conv_ctx(s, NULL, ff_nut_metadata_conv);
  
      return 0;
  
  fail:
      nut_read_close(s);
  
      return AVERROR_INVALIDDATA;
  }
  
  static int read_sm_data(AVFormatContext *s, AVIOContext *bc, AVPacket *pkt, int is_meta, int64_t maxpos)
  {
      int count = ffio_read_varlen(bc);
      int skip_start = 0;
      int skip_end = 0;
      int channels = 0;
      int64_t channel_layout = 0;
      int sample_rate = 0;
      int width = 0;
      int height = 0;
      int i, ret;
  
      for (i=0; i<count; i++) {
          uint8_t name[256], str_value[256], type_str[256];
          int value;
          if (avio_tell(bc) >= maxpos)
              return AVERROR_INVALIDDATA;
          ret = get_str(bc, name, sizeof(name));
          if (ret < 0) {
              av_log(s, AV_LOG_ERROR, "get_str failed while reading sm data\n");
              return ret;
          }
          value = get_s(bc);
  
          if (value == -1) {
              ret = get_str(bc, str_value, sizeof(str_value));
              if (ret < 0) {
                  av_log(s, AV_LOG_ERROR, "get_str failed while reading sm data\n");
                  return ret;
              }
              av_log(s, AV_LOG_WARNING, "Unknown string %s / %s\n", name, str_value);
          } else if (value == -2) {
              uint8_t *dst = NULL;
              int64_t v64, value_len;
  
              ret = get_str(bc, type_str, sizeof(type_str));
              if (ret < 0) {
                  av_log(s, AV_LOG_ERROR, "get_str failed while reading sm data\n");
                  return ret;
              }
              value_len = ffio_read_varlen(bc);
              if (value_len < 0 || value_len >= maxpos - avio_tell(bc))
                  return AVERROR_INVALIDDATA;
              if (!strcmp(name, "Palette")) {
                  dst = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, value_len);
              } else if (!strcmp(name, "Extradata")) {
                  dst = av_packet_new_side_data(pkt, AV_PKT_DATA_NEW_EXTRADATA, value_len);
              } else if (sscanf(name, "CodecSpecificSide%"SCNd64"", &v64) == 1) {
                  dst = av_packet_new_side_data(pkt, AV_PKT_DATA_MATROSKA_BLOCKADDITIONAL, value_len + 8);
                  if(!dst)
                      return AVERROR(ENOMEM);
                  AV_WB64(dst, v64);
                  dst += 8;
              } else if (!strcmp(name, "ChannelLayout") && value_len == 8) {
                  channel_layout = avio_rl64(bc);
                  continue;
              } else {
                  av_log(s, AV_LOG_WARNING, "Unknown data %s / %s\n", name, type_str);
                  avio_skip(bc, value_len);
                  continue;
              }
              if(!dst)
                  return AVERROR(ENOMEM);
              avio_read(bc, dst, value_len);
          } else if (value == -3) {
              value = get_s(bc);
          } else if (value == -4) {
              value = ffio_read_varlen(bc);
          } else if (value < -4) {
              get_s(bc);
          } else {
              if (!strcmp(name, "SkipStart")) {
                  skip_start = value;
              } else if (!strcmp(name, "SkipEnd")) {
                  skip_end = value;
              } else if (!strcmp(name, "Channels")) {
                  channels = value;
              } else if (!strcmp(name, "SampleRate")) {
                  sample_rate = value;
              } else if (!strcmp(name, "Width")) {
                  width = value;
              } else if (!strcmp(name, "Height")) {
                  height = value;
              } else {
                  av_log(s, AV_LOG_WARNING, "Unknown integer %s\n", name);
              }
          }
      }
  
      if (channels || channel_layout || sample_rate || width || height) {
          uint8_t *dst = av_packet_new_side_data(pkt, AV_PKT_DATA_PARAM_CHANGE, 28);
          if (!dst)
              return AVERROR(ENOMEM);
          bytestream_put_le32(&dst,
                              AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_COUNT*(!!channels) +
                              AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_LAYOUT*(!!channel_layout) +
                              AV_SIDE_DATA_PARAM_CHANGE_SAMPLE_RATE*(!!sample_rate) +
                              AV_SIDE_DATA_PARAM_CHANGE_DIMENSIONS*(!!(width|height))
                             );
          if (channels)
              bytestream_put_le32(&dst, channels);
          if (channel_layout)
              bytestream_put_le64(&dst, channel_layout);
          if (sample_rate)
              bytestream_put_le32(&dst, sample_rate);
          if (width || height){
              bytestream_put_le32(&dst, width);
              bytestream_put_le32(&dst, height);
          }
      }
  
      if (skip_start || skip_end) {
          uint8_t *dst = av_packet_new_side_data(pkt, AV_PKT_DATA_SKIP_SAMPLES, 10);
          if (!dst)
              return AVERROR(ENOMEM);
          AV_WL32(dst, skip_start);
          AV_WL32(dst+4, skip_end);
      }
  
      if (avio_tell(bc) >= maxpos)
          return AVERROR_INVALIDDATA;
  
      return 0;
  }
  
  static int decode_frame_header(NUTContext *nut, int64_t *pts, int *stream_id,
                                 uint8_t *header_idx, int frame_code)
  {
      AVFormatContext *s = nut->avf;
      AVIOContext *bc    = s->pb;
      StreamContext *stc;
      int size, flags, size_mul, pts_delta, i, reserved_count, ret;
      uint64_t tmp;
  
      if (!(nut->flags & NUT_PIPE) &&
          avio_tell(bc) > nut->last_syncpoint_pos + nut->max_distance) {
          av_log(s, AV_LOG_ERROR,
                 "Last frame must have been damaged %"PRId64" > %"PRId64" + %d\n",
                 avio_tell(bc), nut->last_syncpoint_pos, nut->max_distance);
          return AVERROR_INVALIDDATA;
      }
  
      flags          = nut->frame_code[frame_code].flags;
      size_mul       = nut->frame_code[frame_code].size_mul;
      size           = nut->frame_code[frame_code].size_lsb;
      *stream_id     = nut->frame_code[frame_code].stream_id;
      pts_delta      = nut->frame_code[frame_code].pts_delta;
      reserved_count = nut->frame_code[frame_code].reserved_count;
      *header_idx    = nut->frame_code[frame_code].header_idx;
  
      if (flags & FLAG_INVALID)
          return AVERROR_INVALIDDATA;
      if (flags & FLAG_CODED)
          flags ^= ffio_read_varlen(bc);
      if (flags & FLAG_STREAM_ID) {
          GET_V(*stream_id, tmp < s->nb_streams);
      }
      stc = &nut->stream[*stream_id];
      if (flags & FLAG_CODED_PTS) {
          int64_t coded_pts = ffio_read_varlen(bc);
          // FIXME check last_pts validity?
          if (coded_pts < (1LL << stc->msb_pts_shift)) {
              *pts = ff_lsb2full(stc, coded_pts);
          } else
              *pts = coded_pts - (1LL << stc->msb_pts_shift);
      } else
          *pts = stc->last_pts + pts_delta;
      if (flags & FLAG_SIZE_MSB)
          size += size_mul * ffio_read_varlen(bc);
      if (flags & FLAG_MATCH_TIME)
          get_s(bc);
      if (flags & FLAG_HEADER_IDX)
          *header_idx = ffio_read_varlen(bc);
      if (flags & FLAG_RESERVED)
          reserved_count = ffio_read_varlen(bc);
      for (i = 0; i < reserved_count; i++) {
          if (bc->eof_reached) {
              av_log(s, AV_LOG_ERROR, "reached EOF while decoding frame header\n");
              return AVERROR_INVALIDDATA;
          }
          ffio_read_varlen(bc);
      }
  
      if (*header_idx >= (unsigned)nut->header_count) {
          av_log(s, AV_LOG_ERROR, "header_idx invalid\n");
          return AVERROR_INVALIDDATA;
      }
      if (size > 4096)
          *header_idx = 0;
      size -= nut->header_len[*header_idx];
  
      if (flags & FLAG_CHECKSUM) {
          avio_rb32(bc); // FIXME check this
      } else if (!(nut->flags & NUT_PIPE) &&
                 size > 2 * nut->max_distance ||
                 FFABS(stc->last_pts - *pts) > stc->max_pts_distance) {
          av_log(s, AV_LOG_ERROR, "frame size > 2max_distance and no checksum\n");
          return AVERROR_INVALIDDATA;
      }
  
      stc->last_pts   = *pts;
      stc->last_flags = flags;
  
      return size;
  fail:
      return ret;
  }
  
  static int decode_frame(NUTContext *nut, AVPacket *pkt, int frame_code)
  {
      AVFormatContext *s = nut->avf;
      AVIOContext *bc    = s->pb;
      int size, stream_id, discard, ret;
      int64_t pts, last_IP_pts;
      StreamContext *stc;
      uint8_t header_idx;
  
      size = decode_frame_header(nut, &pts, &stream_id, &header_idx, frame_code);
      if (size < 0)
          return size;
  
      stc = &nut->stream[stream_id];
  
      if (stc->last_flags & FLAG_KEY)
          stc->skip_until_key_frame = 0;
  
      discard     = s->streams[stream_id]->discard;
      last_IP_pts = s->streams[stream_id]->last_IP_pts;
      if ((discard >= AVDISCARD_NONKEY && !(stc->last_flags & FLAG_KEY)) ||
          (discard >= AVDISCARD_BIDIR  && last_IP_pts != AV_NOPTS_VALUE &&
           last_IP_pts > pts) ||
          discard >= AVDISCARD_ALL ||
          stc->skip_until_key_frame) {
          avio_skip(bc, size);
          return 1;
      }
  
      ret = av_new_packet(pkt, size + nut->header_len[header_idx]);
      if (ret < 0)
          return ret;
      if (nut->header[header_idx])
          memcpy(pkt->data, nut->header[header_idx], nut->header_len[header_idx]);
      pkt->pos = avio_tell(bc); // FIXME
      if (stc->last_flags & FLAG_SM_DATA) {
          int sm_size;
          if (read_sm_data(s, bc, pkt, 0, pkt->pos + size) < 0) {
              ret = AVERROR_INVALIDDATA;
              goto fail;
          }
          if (read_sm_data(s, bc, pkt, 1, pkt->pos + size) < 0) {
              ret = AVERROR_INVALIDDATA;
              goto fail;
          }
          sm_size = avio_tell(bc) - pkt->pos;
          size      -= sm_size;
          pkt->size -= sm_size;
      }
  
      ret = avio_read(bc, pkt->data + nut->header_len[header_idx], size);
      if (ret != size) {
          if (ret < 0)
              goto fail;
      }
      av_shrink_packet(pkt, nut->header_len[header_idx] + ret);
  
      pkt->stream_index = stream_id;
      if (stc->last_flags & FLAG_KEY)
          pkt->flags |= AV_PKT_FLAG_KEY;
      pkt->pts = pts;
  
      return 0;
  fail:
      av_packet_unref(pkt);
      return ret;
  }
  
  static int nut_read_packet(AVFormatContext *s, AVPacket *pkt)
  {
      NUTContext *nut = s->priv_data;
      AVIOContext *bc = s->pb;
      int i, frame_code = 0, ret, skip;
      int64_t ts, back_ptr;
  
      for (;;) {
          int64_t pos  = avio_tell(bc);
          uint64_t tmp = nut->next_startcode;
          nut->next_startcode = 0;
  
          if (tmp) {
              pos -= 8;
          } else {
              frame_code = avio_r8(bc);
              if (avio_feof(bc))
                  return AVERROR_EOF;
              if (frame_code == 'N') {
                  tmp = frame_code;
                  for (i = 1; i < 8; i++)
                      tmp = (tmp << 8) + avio_r8(bc);
              }
          }
          switch (tmp) {
          case MAIN_STARTCODE:
          case STREAM_STARTCODE:
          case INDEX_STARTCODE:
              skip = get_packetheader(nut, bc, 0, tmp);
              avio_skip(bc, skip);
              break;
          case INFO_STARTCODE:
              if (decode_info_header(nut) < 0)
                  goto resync;
              break;
          case SYNCPOINT_STARTCODE:
              if (decode_syncpoint(nut, &ts, &back_ptr) < 0)
                  goto resync;
              frame_code = avio_r8(bc);
          case 0:
              ret = decode_frame(nut, pkt, frame_code);
              if (ret == 0)
                  return 0;
              else if (ret == 1) // OK but discard packet
                  break;
          default:
  resync:
              av_log(s, AV_LOG_DEBUG, "syncing from %"PRId64"\n", pos);
              tmp = find_any_startcode(bc, FFMAX(nut->last_syncpoint_pos, nut->last_resync_pos) + 1);
              nut->last_resync_pos = avio_tell(bc);
              if (tmp == 0)
                  return AVERROR_INVALIDDATA;
              av_log(s, AV_LOG_DEBUG, "sync\n");
              nut->next_startcode = tmp;
          }
      }
  }
  
  static int64_t nut_read_timestamp(AVFormatContext *s, int stream_index,
                                    int64_t *pos_arg, int64_t pos_limit)
  {
      NUTContext *nut = s->priv_data;
      AVIOContext *bc = s->pb;
      int64_t pos, pts, back_ptr;
      av_log(s, AV_LOG_DEBUG, "read_timestamp(X,%d,%"PRId64",%"PRId64")\n",
             stream_index, *pos_arg, pos_limit);
  
      pos = *pos_arg;
      do {
          pos = find_startcode(bc, SYNCPOINT_STARTCODE, pos) + 1;
          if (pos < 1) {
              av_log(s, AV_LOG_ERROR, "read_timestamp failed.\n");
              return AV_NOPTS_VALUE;
          }
      } while (decode_syncpoint(nut, &pts, &back_ptr) < 0);
      *pos_arg = pos - 1;
      av_assert0(nut->last_syncpoint_pos == *pos_arg);
  
      av_log(s, AV_LOG_DEBUG, "return %"PRId64" %"PRId64"\n", pts, back_ptr);
      if (stream_index == -2)
          return back_ptr;
      av_assert0(stream_index == -1);
      return pts;
  }
  
  static int read_seek(AVFormatContext *s, int stream_index,
                       int64_t pts, int flags)
  {
      NUTContext *nut    = s->priv_data;
      AVStream *st       = s->streams[stream_index];
      Syncpoint dummy    = { .ts = pts * av_q2d(st->time_base) * AV_TIME_BASE };
      Syncpoint nopts_sp = { .ts = AV_NOPTS_VALUE, .back_ptr = AV_NOPTS_VALUE };
      Syncpoint *sp, *next_node[2] = { &nopts_sp, &nopts_sp };
      int64_t pos, pos2, ts;
      int i;
  
      if (nut->flags & NUT_PIPE) {
          return AVERROR(ENOSYS);
      }
  
      if (st->internal->index_entries) {
          int index = av_index_search_timestamp(st, pts, flags);
          if (index < 0)
              index = av_index_search_timestamp(st, pts, flags ^ AVSEEK_FLAG_BACKWARD);
          if (index < 0)
              return -1;
  
          pos2 = st->internal->index_entries[index].pos;
          ts   = st->internal->index_entries[index].timestamp;
      } else {
          av_tree_find(nut->syncpoints, &dummy, ff_nut_sp_pts_cmp,
                       (void **) next_node);
          av_log(s, AV_LOG_DEBUG, "%"PRIu64"-%"PRIu64" %"PRId64"-%"PRId64"\n",
                 next_node[0]->pos, next_node[1]->pos, next_node[0]->ts,
                 next_node[1]->ts);
          pos = ff_gen_search(s, -1, dummy.ts, next_node[0]->pos,
                              next_node[1]->pos, next_node[1]->pos,
                              next_node[0]->ts, next_node[1]->ts,
                              AVSEEK_FLAG_BACKWARD, &ts, nut_read_timestamp);
          if (pos < 0)
              return pos;
  
          if (!(flags & AVSEEK_FLAG_BACKWARD)) {
              dummy.pos    = pos + 16;
              next_node[1] = &nopts_sp;
              av_tree_find(nut->syncpoints, &dummy, ff_nut_sp_pos_cmp,
                           (void **) next_node);
              pos2 = ff_gen_search(s, -2, dummy.pos, next_node[0]->pos,
                                   next_node[1]->pos, next_node[1]->pos,
                                   next_node[0]->back_ptr, next_node[1]->back_ptr,
                                   flags, &ts, nut_read_timestamp);
              if (pos2 >= 0)
                  pos = pos2;
              // FIXME dir but I think it does not matter
          }
          dummy.pos = pos;
          sp = av_tree_find(nut->syncpoints, &dummy, ff_nut_sp_pos_cmp,
                            NULL);
  
          av_assert0(sp);
          pos2 = sp->back_ptr - 15;
      }
      av_log(s, AV_LOG_DEBUG, "SEEKTO: %"PRId64"\n", pos2);
      pos = find_startcode(s->pb, SYNCPOINT_STARTCODE, pos2);
      avio_seek(s->pb, pos, SEEK_SET);
      nut->last_syncpoint_pos = pos;
      av_log(s, AV_LOG_DEBUG, "SP: %"PRId64"\n", pos);
      if (pos2 > pos || pos2 + 15 < pos)
          av_log(s, AV_LOG_ERROR, "no syncpoint at backptr pos\n");
      for (i = 0; i < s->nb_streams; i++)
          nut->stream[i].skip_until_key_frame = 1;
  
      nut->last_resync_pos = 0;
  
      return 0;
  }
  
  AVInputFormat ff_nut_demuxer = {
      .name           = "nut",
      .long_name      = NULL_IF_CONFIG_SMALL("NUT"),
      .flags          = AVFMT_SEEK_TO_PTS,
      .priv_data_size = sizeof(NUTContext),
      .read_probe     = nut_probe,
      .read_header    = nut_read_header,
      .read_packet    = nut_read_packet,
      .read_close     = nut_read_close,
      .read_seek      = read_seek,
      .extensions     = "nut",
      .codec_tag      = ff_nut_codec_tags,
  };
  