text: /*
   * AVI demuxer
   * Copyright (c) 2001 Fabrice Bellard
   *
   * 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 <inttypes.h>
  
  #include "libavutil/avassert.h"
  #include "libavutil/avstring.h"
  #include "libavutil/opt.h"
  #include "libavutil/dict.h"
  #include "libavutil/internal.h"
  #include "libavutil/intreadwrite.h"
  #include "libavutil/mathematics.h"
  #include "avformat.h"
  #include "avi.h"
  #include "dv.h"
  #include "internal.h"
  #include "isom.h"
  #include "riff.h"
  #include "libavcodec/bytestream.h"
  #include "libavcodec/exif.h"
  #include "libavcodec/internal.h"
  
  typedef struct AVIStream {
      int64_t frame_offset;   /* current frame (video) or byte (audio) counter
                               * (used to compute the pts) */
      int remaining;
      int packet_size;
  
      uint32_t handler;
      uint32_t scale;
      uint32_t rate;
      int sample_size;        /* size of one sample (or packet)
                               * (in the rate/scale sense) in bytes */
  
      int64_t cum_len;        /* temporary storage (used during seek) */
      int prefix;             /* normally 'd'<<8 + 'c' or 'w'<<8 + 'b' */
      int prefix_count;
      uint32_t pal[256];
      int has_pal;
      int dshow_block_align;  /* block align variable used to emulate bugs in
                               * the MS dshow demuxer */
  
      AVFormatContext *sub_ctx;
      AVPacket sub_pkt;
      AVBufferRef *sub_buffer;
  
      int64_t seek_pos;
  } AVIStream;
  
  typedef struct AVIContext {
      const AVClass *class;
      int64_t riff_end;
      int64_t movi_end;
      int64_t fsize;
      int64_t io_fsize;
      int64_t movi_list;
      int64_t last_pkt_pos;
      int index_loaded;
      int is_odml;
      int non_interleaved;
      int stream_index;
      DVDemuxContext *dv_demux;
      int odml_depth;
      int use_odml;
  #define MAX_ODML_DEPTH 1000
      int64_t dts_max;
  } AVIContext;
  
  
  static const AVOption options[] = {
      { "use_odml", "use odml index", offsetof(AVIContext, use_odml), AV_OPT_TYPE_BOOL, {.i64 = 1}, -1, 1, AV_OPT_FLAG_DECODING_PARAM},
      { NULL },
  };
  
  static const AVClass demuxer_class = {
      .class_name = "avi",
      .item_name  = av_default_item_name,
      .option     = options,
      .version    = LIBAVUTIL_VERSION_INT,
      .category   = AV_CLASS_CATEGORY_DEMUXER,
  };
  
  
  static const char avi_headers[][8] = {
      { 'R', 'I', 'F', 'F', 'A', 'V', 'I', ' '  },
      { 'R', 'I', 'F', 'F', 'A', 'V', 'I', 'X'  },
      { 'R', 'I', 'F', 'F', 'A', 'V', 'I', 0x19 },
      { 'O', 'N', '2', ' ', 'O', 'N', '2', 'f'  },
      { 'R', 'I', 'F', 'F', 'A', 'M', 'V', ' '  },
      { 0 }
  };
  
  static const AVMetadataConv avi_metadata_conv[] = {
      { "strn", "title" },
      { 0 },
  };
  
  static int avi_read_close(AVFormatContext *s);
  static int avi_load_index(AVFormatContext *s);
  static int guess_ni_flag(AVFormatContext *s);
  
  #define print_tag(s, str, tag, size)                                      \
      av_log(s, AV_LOG_TRACE, "pos:%"PRIX64" %s: tag=%s size=0x%x\n", \
             avio_tell(pb), str, av_fourcc2str(tag), size)                  \
  
  static inline int get_duration(AVIStream *ast, int len)
  {
      if (ast->sample_size)
          return len;
      else if (ast->dshow_block_align)
          return (len + (int64_t)ast->dshow_block_align - 1) / ast->dshow_block_align;
      else
          return 1;
  }
  
  static int get_riff(AVFormatContext *s, AVIOContext *pb)
  {
      AVIContext *avi = s->priv_data;
      char header[8] = {0};
      int i;
  
      /* check RIFF header */
      avio_read(pb, header, 4);
      avi->riff_end  = avio_rl32(pb); /* RIFF chunk size */
      avi->riff_end += avio_tell(pb); /* RIFF chunk end */
      avio_read(pb, header + 4, 4);
  
      for (i = 0; avi_headers[i][0]; i++)
          if (!memcmp(header, avi_headers[i], 8))
              break;
      if (!avi_headers[i][0])
          return AVERROR_INVALIDDATA;
  
      if (header[7] == 0x19)
          av_log(s, AV_LOG_INFO,
                 "This file has been generated by a totally broken muxer.\n");
  
      return 0;
  }
  
  static int read_odml_index(AVFormatContext *s, int64_t frame_num)
  {
      AVIContext *avi     = s->priv_data;
      AVIOContext *pb     = s->pb;
      int longs_per_entry = avio_rl16(pb);
      int index_sub_type  = avio_r8(pb);
      int index_type      = avio_r8(pb);
      int entries_in_use  = avio_rl32(pb);
      int chunk_id        = avio_rl32(pb);
      int64_t base        = avio_rl64(pb);
      int stream_id       = ((chunk_id      & 0xFF) - '0') * 10 +
                            ((chunk_id >> 8 & 0xFF) - '0');
      AVStream *st;
      AVIStream *ast;
      int i;
      int64_t last_pos = -1;
      int64_t filesize = avi->fsize;
  
      av_log(s, AV_LOG_TRACE,
              "longs_per_entry:%d index_type:%d entries_in_use:%d "
              "chunk_id:%X base:%16"PRIX64" frame_num:%"PRId64"\n",
              longs_per_entry,
              index_type,
              entries_in_use,
              chunk_id,
              base,
              frame_num);
  
      if (stream_id >= s->nb_streams || stream_id < 0)
          return AVERROR_INVALIDDATA;
      st  = s->streams[stream_id];
      ast = st->priv_data;
  
      if (index_sub_type)
          return AVERROR_INVALIDDATA;
  
      avio_rl32(pb);
  
      if (index_type && longs_per_entry != 2)
          return AVERROR_INVALIDDATA;
      if (index_type > 1)
          return AVERROR_INVALIDDATA;
  
      if (filesize > 0 && base >= filesize) {
          av_log(s, AV_LOG_ERROR, "ODML index invalid\n");
          if (base >> 32 == (base & 0xFFFFFFFF) &&
              (base & 0xFFFFFFFF) < filesize    &&
              filesize <= 0xFFFFFFFF)
              base &= 0xFFFFFFFF;
          else
              return AVERROR_INVALIDDATA;
      }
  
      for (i = 0; i < entries_in_use; i++) {
          if (index_type) {
              int64_t pos = avio_rl32(pb) + base - 8;
              int len     = avio_rl32(pb);
              int key     = len >= 0;
              len &= 0x7FFFFFFF;
  
              av_log(s, AV_LOG_TRACE, "pos:%"PRId64", len:%X\n", pos, len);
  
              if (avio_feof(pb))
                  return AVERROR_INVALIDDATA;
  
              if (last_pos == pos || pos == base - 8)
                  avi->non_interleaved = 1;
              if (last_pos != pos && len)
                  av_add_index_entry(st, pos, ast->cum_len, len, 0,
                                     key ? AVINDEX_KEYFRAME : 0);
  
              ast->cum_len += get_duration(ast, len);
              last_pos      = pos;
          } else {
              int64_t offset, pos;
              int duration;
              offset = avio_rl64(pb);
              avio_rl32(pb);       /* size */
              duration = avio_rl32(pb);
  
              if (avio_feof(pb) || offset > INT64_MAX - 8)
                  return AVERROR_INVALIDDATA;
  
              pos = avio_tell(pb);
  
              if (avi->odml_depth > MAX_ODML_DEPTH) {
                  av_log(s, AV_LOG_ERROR, "Too deeply nested ODML indexes\n");
                  return AVERROR_INVALIDDATA;
              }
  
              if (avio_seek(pb, offset + 8, SEEK_SET) < 0)
                  return -1;
              avi->odml_depth++;
              read_odml_index(s, frame_num);
              avi->odml_depth--;
              frame_num += duration;
  
              if (avio_seek(pb, pos, SEEK_SET) < 0) {
                  av_log(s, AV_LOG_ERROR, "Failed to restore position after reading index\n");
                  return -1;
              }
  
          }
      }
      avi->index_loaded = 2;
      return 0;
  }
  
  static void clean_index(AVFormatContext *s)
  {
      int i;
      int64_t j;
  
      for (i = 0; i < s->nb_streams; i++) {
          AVStream *st   = s->streams[i];
          AVIStream *ast = st->priv_data;
          int n          = st->nb_index_entries;
          int max        = ast->sample_size;
          int64_t pos, size, ts;
  
          if (n != 1 || ast->sample_size == 0)
              continue;
  
          while (max < 1024)
              max += max;
  
          pos  = st->index_entries[0].pos;
          size = st->index_entries[0].size;
          ts   = st->index_entries[0].timestamp;
  
          for (j = 0; j < size; j += max)
              av_add_index_entry(st, pos + j, ts + j, FFMIN(max, size - j), 0,
                                 AVINDEX_KEYFRAME);
      }
  }
  
  static int avi_read_tag(AVFormatContext *s, AVStream *st, uint32_t tag,
                          uint32_t size)
  {
      AVIOContext *pb = s->pb;
      char key[5]     = { 0 };
      char *value;
  
      size += (size & 1);
  
      if (size == UINT_MAX)
          return AVERROR(EINVAL);
      value = av_malloc(size + 1);
      if (!value)
          return AVERROR(ENOMEM);
      if (avio_read(pb, value, size) != size) {
          av_freep(&value);
          return AVERROR_INVALIDDATA;
      }
      value[size] = 0;
  
      AV_WL32(key, tag);
  
      return av_dict_set(st ? &st->metadata : &s->metadata, key, value,
                         AV_DICT_DONT_STRDUP_VAL);
  }
  
  static const char months[12][4] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun",
                                      "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };
  
  static void avi_metadata_creation_time(AVDictionary **metadata, char *date)
  {
      char month[4], time[9], buffer[64];
      int i, day, year;
      /* parse standard AVI date format (ie. "Mon Mar 10 15:04:43 2003") */
      if (sscanf(date, "%*3s%*[ ]%3s%*[ ]%2d%*[ ]%8s%*[ ]%4d",
                 month, &day, time, &year) == 4) {
          for (i = 0; i < 12; i++)
              if (!av_strcasecmp(month, months[i])) {
                  snprintf(buffer, sizeof(buffer), "%.4d-%.2d-%.2d %s",
                           year, i + 1, day, time);
                  av_dict_set(metadata, "creation_time", buffer, 0);
              }
      } else if (date[4] == '/' && date[7] == '/') {
          date[4] = date[7] = '-';
          av_dict_set(metadata, "creation_time", date, 0);
      }
  }
  
  static void avi_read_nikon(AVFormatContext *s, uint64_t end)
  {
      while (avio_tell(s->pb) < end && !avio_feof(s->pb)) {
          uint32_t tag  = avio_rl32(s->pb);
          uint32_t size = avio_rl32(s->pb);
          switch (tag) {
          case MKTAG('n', 'c', 't', 'g'):  /* Nikon Tags */
          {
              uint64_t tag_end = avio_tell(s->pb) + size;
              while (avio_tell(s->pb) < tag_end && !avio_feof(s->pb)) {
                  uint16_t tag     = avio_rl16(s->pb);
                  uint16_t size    = avio_rl16(s->pb);
                  const char *name = NULL;
                  char buffer[64]  = { 0 };
                  size = FFMIN(size, tag_end - avio_tell(s->pb));
                  size -= avio_read(s->pb, buffer,
                                    FFMIN(size, sizeof(buffer) - 1));
                  switch (tag) {
                  case 0x03:
                      name = "maker";
                      break;
                  case 0x04:
                      name = "model";
                      break;
                  case 0x13:
                      name = "creation_time";
                      if (buffer[4] == ':' && buffer[7] == ':')
                          buffer[4] = buffer[7] = '-';
                      break;
                  }
                  if (name)
                      av_dict_set(&s->metadata, name, buffer, 0);
                  avio_skip(s->pb, size);
              }
              break;
          }
          default:
              avio_skip(s->pb, size);
              break;
          }
      }
  }
  
  static int avi_extract_stream_metadata(AVFormatContext *s, AVStream *st)
  {
      GetByteContext gb;
      uint8_t *data = st->codecpar->extradata;
      int data_size = st->codecpar->extradata_size;
      int tag, offset;
  
      if (!data || data_size < 8) {
          return AVERROR_INVALIDDATA;
      }
  
      bytestream2_init(&gb, data, data_size);
  
      tag = bytestream2_get_le32(&gb);
  
      switch (tag) {
      case MKTAG('A', 'V', 'I', 'F'):
          // skip 4 byte padding
          bytestream2_skip(&gb, 4);
          offset = bytestream2_tell(&gb);
  
          // decode EXIF tags from IFD, AVI is always little-endian
          return avpriv_exif_decode_ifd(s, data + offset, data_size - offset,
                                        1, 0, &st->metadata);
          break;
      case MKTAG('C', 'A', 'S', 'I'):
          avpriv_request_sample(s, "RIFF stream data tag type CASI (%u)", tag);
          break;
      case MKTAG('Z', 'o', 'r', 'a'):
          avpriv_request_sample(s, "RIFF stream data tag type Zora (%u)", tag);
          break;
      default:
          break;
      }
  
      return 0;
  }
  
  static int calculate_bitrate(AVFormatContext *s)
  {
      AVIContext *avi = s->priv_data;
      int i, j;
      int64_t lensum = 0;
      int64_t maxpos = 0;
  
      for (i = 0; i<s->nb_streams; i++) {
          int64_t len = 0;
          AVStream *st = s->streams[i];
  
          if (!st->nb_index_entries)
              continue;
  
          for (j = 0; j < st->nb_index_entries; j++)
              len += st->index_entries[j].size;
          maxpos = FFMAX(maxpos, st->index_entries[j-1].pos);
          lensum += len;
      }
      if (maxpos < av_rescale(avi->io_fsize, 9, 10)) // index does not cover the whole file
          return 0;
      if (lensum*9/10 > maxpos || lensum < maxpos*9/10) // frame sum and filesize mismatch
          return 0;
  
      for (i = 0; i<s->nb_streams; i++) {
          int64_t len = 0;
          AVStream *st = s->streams[i];
          int64_t duration;
          int64_t bitrate;
  
          for (j = 0; j < st->nb_index_entries; j++)
              len += st->index_entries[j].size;
  
          if (st->nb_index_entries < 2 || st->codecpar->bit_rate > 0)
              continue;
          duration = st->index_entries[j-1].timestamp - st->index_entries[0].timestamp;
          bitrate = av_rescale(8*len, st->time_base.den, duration * st->time_base.num);
          if (bitrate > 0) {
              st->codecpar->bit_rate = bitrate;
          }
      }
      return 1;
  }
  
  #define RETURN_ERROR(code) do { ret = (code); goto fail; } while (0)
  static int avi_read_header(AVFormatContext *s)
  {
      AVIContext *avi = s->priv_data;
      AVIOContext *pb = s->pb;
      unsigned int tag, tag1, handler;
      int codec_type, stream_index, frame_period;
      unsigned int size;
      int i;
      AVStream *st;
      AVIStream *ast      = NULL;
      int avih_width      = 0, avih_height = 0;
      int amv_file_format = 0;
      uint64_t list_end   = 0;
      int64_t pos;
      int ret;
      AVDictionaryEntry *dict_entry;
  
      avi->stream_index = -1;
  
      ret = get_riff(s, pb);
      if (ret < 0)
          return ret;
  
      av_log(avi, AV_LOG_DEBUG, "use odml:%d\n", avi->use_odml);
  
      avi->io_fsize = avi->fsize = avio_size(pb);
      if (avi->fsize <= 0 || avi->fsize < avi->riff_end)
          avi->fsize = avi->riff_end == 8 ? INT64_MAX : avi->riff_end;
  
      /* first list tag */
      stream_index = -1;
      codec_type   = -1;
      frame_period = 0;
      for (;;) {
          if (avio_feof(pb))
              RETURN_ERROR(AVERROR_INVALIDDATA);
          tag  = avio_rl32(pb);
          size = avio_rl32(pb);
  
          print_tag(s, "tag", tag, size);
  
          switch (tag) {
          case MKTAG('L', 'I', 'S', 'T'):
              list_end = avio_tell(pb) + size;
              /* Ignored, except at start of video packets. */
              tag1 = avio_rl32(pb);
  
              print_tag(s, "list", tag1, 0);
  
              if (tag1 == MKTAG('m', 'o', 'v', 'i')) {
                  avi->movi_list = avio_tell(pb) - 4;
                  if (size)
                      avi->movi_end = avi->movi_list + size + (size & 1);
                  else
                      avi->movi_end = avi->fsize;
                  av_log(s, AV_LOG_TRACE, "movi end=%"PRIx64"\n", avi->movi_end);
                  goto end_of_header;
              } else if (tag1 == MKTAG('I', 'N', 'F', 'O'))
                  ff_read_riff_info(s, size - 4);
              else if (tag1 == MKTAG('n', 'c', 'd', 't'))
                  avi_read_nikon(s, list_end);
  
              break;
          case MKTAG('I', 'D', 'I', 'T'):
          {
              unsigned char date[64] = { 0 };
              size += (size & 1);
              size -= avio_read(pb, date, FFMIN(size, sizeof(date) - 1));
              avio_skip(pb, size);
              avi_metadata_creation_time(&s->metadata, date);
              break;
          }
          case MKTAG('d', 'm', 'l', 'h'):
              avi->is_odml = 1;
              avio_skip(pb, size + (size & 1));
              break;
          case MKTAG('a', 'm', 'v', 'h'):
              amv_file_format = 1;
          case MKTAG('a', 'v', 'i', 'h'):
              /* AVI header */
              /* using frame_period is bad idea */
              frame_period = avio_rl32(pb);
              avio_rl32(pb); /* max. bytes per second */
              avio_rl32(pb);
              avi->non_interleaved |= avio_rl32(pb) & AVIF_MUSTUSEINDEX;
  
              avio_skip(pb, 2 * 4);
              avio_rl32(pb);
              avio_rl32(pb);
              avih_width  = avio_rl32(pb);
              avih_height = avio_rl32(pb);
  
              avio_skip(pb, size - 10 * 4);
              break;
          case MKTAG('s', 't', 'r', 'h'):
              /* stream header */
  
              tag1    = avio_rl32(pb);
              handler = avio_rl32(pb); /* codec tag */
  
              if (tag1 == MKTAG('p', 'a', 'd', 's')) {
                  avio_skip(pb, size - 8);
                  break;
              } else {
                  stream_index++;
                  st = avformat_new_stream(s, NULL);
                  if (!st)
                      RETURN_ERROR(AVERROR(ENOMEM));
  
                  st->id = stream_index;
                  ast    = av_mallocz(sizeof(AVIStream));
                  if (!ast)
                      RETURN_ERROR(AVERROR(ENOMEM));
                  st->priv_data = ast;
              }
              if (amv_file_format)
                  tag1 = stream_index ? MKTAG('a', 'u', 'd', 's')
                                      : MKTAG('v', 'i', 'd', 's');
  
              print_tag(s, "strh", tag1, -1);
  
              if (tag1 == MKTAG('i', 'a', 'v', 's') ||
                  tag1 == MKTAG('i', 'v', 'a', 's')) {
                  int64_t dv_dur;
  
                  /* After some consideration -- I don't think we
                   * have to support anything but DV in type1 AVIs. */
                  if (s->nb_streams != 1)
                      RETURN_ERROR(AVERROR_INVALIDDATA);
  
                  if (handler != MKTAG('d', 'v', 's', 'd') &&
                      handler != MKTAG('d', 'v', 'h', 'd') &&
                      handler != MKTAG('d', 'v', 's', 'l'))
                      return AVERROR_INVALIDDATA;
  
                  if (!CONFIG_DV_DEMUXER)
                      return AVERROR_DEMUXER_NOT_FOUND;
  
                  ast = s->streams[0]->priv_data;
                  st->priv_data = NULL;
                  ff_free_stream(s, st);
  
                  avi->dv_demux = avpriv_dv_init_demux(s);
                  if (!avi->dv_demux) {
                      av_free(ast);
                      return AVERROR(ENOMEM);
                  }
  
                  s->streams[0]->priv_data = ast;
                  avio_skip(pb, 3 * 4);
                  ast->scale = avio_rl32(pb);
                  ast->rate  = avio_rl32(pb);
                  avio_skip(pb, 4);  /* start time */
  
                  dv_dur = avio_rl32(pb);
                  if (ast->scale > 0 && ast->rate > 0 && dv_dur > 0) {
                      dv_dur     *= AV_TIME_BASE;
                      s->duration = av_rescale(dv_dur, ast->scale, ast->rate);
                  }
                  /* else, leave duration alone; timing estimation in utils.c
                   * will make a guess based on bitrate. */
  
                  stream_index = s->nb_streams - 1;
                  avio_skip(pb, size - 9 * 4);
                  break;
              }
  
              av_assert0(stream_index < s->nb_streams);
              ast->handler = handler;
  
              avio_rl32(pb); /* flags */
              avio_rl16(pb); /* priority */
              avio_rl16(pb); /* language */
              avio_rl32(pb); /* initial frame */
              ast->scale = avio_rl32(pb);
              ast->rate  = avio_rl32(pb);
              if (!(ast->scale && ast->rate)) {
                  av_log(s, AV_LOG_WARNING,
                         "scale/rate is %"PRIu32"/%"PRIu32" which is invalid. "
                         "(This file has been generated by broken software.)\n",
                         ast->scale,
                         ast->rate);
                  if (frame_period) {
                      ast->rate  = 1000000;
                      ast->scale = frame_period;
                  } else {
                      ast->rate  = 25;
                      ast->scale = 1;
                  }
              }
              avpriv_set_pts_info(st, 64, ast->scale, ast->rate);
  
              ast->cum_len  = avio_rl32(pb); /* start */
              st->nb_frames = avio_rl32(pb);
  
              st->start_time = 0;
              avio_rl32(pb); /* buffer size */
              avio_rl32(pb); /* quality */
              if (ast->cum_len > 3600LL * ast->rate / ast->scale) {
                  av_log(s, AV_LOG_ERROR, "crazy start time, iam scared, giving up\n");
                  ast->cum_len = 0;
              }
              ast->sample_size = avio_rl32(pb);
              ast->cum_len    *= FFMAX(1, ast->sample_size);
              av_log(s, AV_LOG_TRACE, "%"PRIu32" %"PRIu32" %d\n",
                      ast->rate, ast->scale, ast->sample_size);
  
              switch (tag1) {
              case MKTAG('v', 'i', 'd', 's'):
                  codec_type = AVMEDIA_TYPE_VIDEO;
  
                  ast->sample_size = 0;
                  st->avg_frame_rate = av_inv_q(st->time_base);
                  break;
              case MKTAG('a', 'u', 'd', 's'):
                  codec_type = AVMEDIA_TYPE_AUDIO;
                  break;
              case MKTAG('t', 'x', 't', 's'):
                  codec_type = AVMEDIA_TYPE_SUBTITLE;
                  break;
              case MKTAG('d', 'a', 't', 's'):
                  codec_type = AVMEDIA_TYPE_DATA;
                  break;
              default:
                  av_log(s, AV_LOG_INFO, "unknown stream type %X\n", tag1);
              }
  
              if (ast->sample_size < 0) {
                  if (s->error_recognition & AV_EF_EXPLODE) {
                      av_log(s, AV_LOG_ERROR,
                             "Invalid sample_size %d at stream %d\n",
                             ast->sample_size,
                             stream_index);
                      RETURN_ERROR(AVERROR_INVALIDDATA);
                  }
                  av_log(s, AV_LOG_WARNING,
                         "Invalid sample_size %d at stream %d "
                         "setting it to 0\n",
                         ast->sample_size,
                         stream_index);
                  ast->sample_size = 0;
              }
  
              if (ast->sample_size == 0) {
                  st->duration = st->nb_frames;
                  if (st->duration > 0 && avi->io_fsize > 0 && avi->riff_end > avi->io_fsize) {
                      av_log(s, AV_LOG_DEBUG, "File is truncated adjusting duration\n");
                      st->duration = av_rescale(st->duration, avi->io_fsize, avi->riff_end);
                  }
              }
              ast->frame_offset = ast->cum_len;
              avio_skip(pb, size - 12 * 4);
              break;
          case MKTAG('s', 't', 'r', 'f'):
              /* stream header */
              if (!size && (codec_type == AVMEDIA_TYPE_AUDIO ||
                            codec_type == AVMEDIA_TYPE_VIDEO))
                  break;
              if (stream_index >= (unsigned)s->nb_streams || avi->dv_demux) {
                  avio_skip(pb, size);
              } else {
                  uint64_t cur_pos = avio_tell(pb);
                  unsigned esize;
                  if (cur_pos < list_end)
                      size = FFMIN(size, list_end - cur_pos);
                  st = s->streams[stream_index];
                  if (st->codecpar->codec_type != AVMEDIA_TYPE_UNKNOWN) {
                      avio_skip(pb, size);
                      break;
                  }
                  switch (codec_type) {
                  case AVMEDIA_TYPE_VIDEO:
                      if (amv_file_format) {
                          st->codecpar->width      = avih_width;
                          st->codecpar->height     = avih_height;
                          st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
                          st->codecpar->codec_id   = AV_CODEC_ID_AMV;
                          avio_skip(pb, size);
                          break;
                      }
                      tag1 = ff_get_bmp_header(pb, st, &esize);
  
                      if (tag1 == MKTAG('D', 'X', 'S', 'B') ||
                          tag1 == MKTAG('D', 'X', 'S', 'A')) {
                          st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
                          st->codecpar->codec_tag  = tag1;
                          st->codecpar->codec_id   = AV_CODEC_ID_XSUB;
                          break;
                      }
  
                      if (size > 10 * 4 && size < (1 << 30) && size < avi->fsize) {
                          if (esize == size-1 && (esize&1)) {
                              st->codecpar->extradata_size = esize - 10 * 4;
                          } else
                              st->codecpar->extradata_size =  size - 10 * 4;
                          if (st->codecpar->extradata) {
                              av_log(s, AV_LOG_WARNING, "New extradata in strf chunk, freeing previous one.\n");
                          }
                          ret = ff_get_extradata(s, st->codecpar, pb,
                                                 st->codecpar->extradata_size);
                          if (ret < 0)
                              return ret;
                      }
  
                      // FIXME: check if the encoder really did this correctly
                      if (st->codecpar->extradata_size & 1)
                          avio_r8(pb);
  
                      /* Extract palette from extradata if bpp <= 8.
                       * This code assumes that extradata contains only palette.
                       * This is true for all paletted codecs implemented in
                       * FFmpeg. */
                      if (st->codecpar->extradata_size &&
                          (st->codecpar->bits_per_coded_sample <= 8)) {
                          int pal_size = (1 << st->codecpar->bits_per_coded_sample) << 2;
                          const uint8_t *pal_src;
  
                          pal_size = FFMIN(pal_size, st->codecpar->extradata_size);
                          pal_src  = st->codecpar->extradata +
                                     st->codecpar->extradata_size - pal_size;
                          /* Exclude the "BottomUp" field from the palette */
                          if (pal_src - st->codecpar->extradata >= 9 &&
                              !memcmp(st->codecpar->extradata + st->codecpar->extradata_size - 9, "BottomUp", 9))
                              pal_src -= 9;
                          for (i = 0; i < pal_size / 4; i++)
                              ast->pal[i] = 0xFFU<<24 | AV_RL32(pal_src + 4 * i);
                          ast->has_pal = 1;
                      }
  
                      print_tag(s, "video", tag1, 0);
  
                      st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
                      st->codecpar->codec_tag  = tag1;
                      st->codecpar->codec_id   = ff_codec_get_id(ff_codec_bmp_tags,
                                                              tag1);
                      /* If codec is not found yet, try with the mov tags. */
                      if (!st->codecpar->codec_id) {
                          st->codecpar->codec_id =
                              ff_codec_get_id(ff_codec_movvideo_tags, tag1);
                          if (st->codecpar->codec_id)
                             av_log(s, AV_LOG_WARNING,
                                    "mov tag found in avi (fourcc %s)\n",
                                    av_fourcc2str(tag1));
                      }
                      if (!st->codecpar->codec_id)
                          st->codecpar->codec_id = ff_codec_get_id(ff_codec_bmp_tags_unofficial, tag1);
  
                      /* This is needed to get the pict type which is necessary
                       * for generating correct pts. */
                      st->need_parsing = AVSTREAM_PARSE_HEADERS;
  
                      if (st->codecpar->codec_id == AV_CODEC_ID_MPEG4 &&
                          ast->handler == MKTAG('X', 'V', 'I', 'D'))
                          st->codecpar->codec_tag = MKTAG('X', 'V', 'I', 'D');
  
                      if (st->codecpar->codec_tag == MKTAG('V', 'S', 'S', 'H'))
                          st->need_parsing = AVSTREAM_PARSE_FULL;
                      if (st->codecpar->codec_id == AV_CODEC_ID_RV40)
                          st->need_parsing = AVSTREAM_PARSE_NONE;
                      if (st->codecpar->codec_id == AV_CODEC_ID_HEVC &&
                          st->codecpar->codec_tag == MKTAG('H', '2', '6', '5'))
                          st->need_parsing = AVSTREAM_PARSE_FULL;
  
                      if (st->codecpar->codec_tag == 0 && st->codecpar->height > 0 &&
                          st->codecpar->extradata_size < 1U << 30) {
                          st->codecpar->extradata_size += 9;
                          if ((ret = av_reallocp(&st->codecpar->extradata,
                                                 st->codecpar->extradata_size +
                                                 AV_INPUT_BUFFER_PADDING_SIZE)) < 0) {
                              st->codecpar->extradata_size = 0;
                              return ret;
                          } else
                              memcpy(st->codecpar->extradata + st->codecpar->extradata_size - 9,
                                     "BottomUp", 9);
                      }
                      st->codecpar->height = FFABS(st->codecpar->height);
  
  //                    avio_skip(pb, size - 5 * 4);
                      break;
                  case AVMEDIA_TYPE_AUDIO:
                      ret = ff_get_wav_header(s, pb, st->codecpar, size, 0);
                      if (ret < 0)
                          return ret;
                      ast->dshow_block_align = st->codecpar->block_align;
                      if (ast->sample_size && st->codecpar->block_align &&
                          ast->sample_size != st->codecpar->block_align) {
                          av_log(s,
                                 AV_LOG_WARNING,
                                 "sample size (%d) != block align (%d)\n",
                                 ast->sample_size,
                                 st->codecpar->block_align);
                          ast->sample_size = st->codecpar->block_align;
                      }
                      /* 2-aligned
                       * (fix for Stargate SG-1 - 3x18 - Shades of Grey.avi) */
                      if (size & 1)
                          avio_skip(pb, 1);
                      /* Force parsing as several audio frames can be in
                       * one packet and timestamps refer to packet start. */
                      st->need_parsing = AVSTREAM_PARSE_TIMESTAMPS;
                      /* ADTS header is in extradata, AAC without header must be
                       * stored as exact frames. Parser not needed and it will
                       * fail. */
                      if (st->codecpar->codec_id == AV_CODEC_ID_AAC &&
                          st->codecpar->extradata_size)
                          st->need_parsing = AVSTREAM_PARSE_NONE;
                      // The flac parser does not work with AVSTREAM_PARSE_TIMESTAMPS
                      if (st->codecpar->codec_id == AV_CODEC_ID_FLAC)
                          st->need_parsing = AVSTREAM_PARSE_NONE;
                      /* AVI files with Xan DPCM audio (wrongly) declare PCM
                       * audio in the header but have Axan as stream_code_tag. */
                      if (ast->handler == AV_RL32("Axan")) {
                          st->codecpar->codec_id  = AV_CODEC_ID_XAN_DPCM;
                          st->codecpar->codec_tag = 0;
                          ast->dshow_block_align = 0;
                      }
                      if (amv_file_format) {
                          st->codecpar->codec_id    = AV_CODEC_ID_ADPCM_IMA_AMV;
                          ast->dshow_block_align = 0;
                      }
                      if ((st->codecpar->codec_id == AV_CODEC_ID_AAC  ||
                           st->codecpar->codec_id == AV_CODEC_ID_FLAC ||
                           st->codecpar->codec_id == AV_CODEC_ID_MP2 ) && ast->dshow_block_align <= 4 && ast->dshow_block_align) {
                          av_log(s, AV_LOG_DEBUG, "overriding invalid dshow_block_align of %d\n", ast->dshow_block_align);
                          ast->dshow_block_align = 0;
                      }
                      if (st->codecpar->codec_id == AV_CODEC_ID_AAC && ast->dshow_block_align == 1024 && ast->sample_size == 1024 ||
                         st->codecpar->codec_id == AV_CODEC_ID_AAC && ast->dshow_block_align == 4096 && ast->sample_size == 4096 ||
                         st->codecpar->codec_id == AV_CODEC_ID_MP3 && ast->dshow_block_align == 1152 && ast->sample_size == 1152) {
                          av_log(s, AV_LOG_DEBUG, "overriding sample_size\n");
                          ast->sample_size = 0;
                      }
                      break;
                  case AVMEDIA_TYPE_SUBTITLE:
                      st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
                      st->request_probe= 1;
                      avio_skip(pb, size);
                      break;
                  default:
                      st->codecpar->codec_type = AVMEDIA_TYPE_DATA;
                      st->codecpar->codec_id   = AV_CODEC_ID_NONE;
                      st->codecpar->codec_tag  = 0;
                      avio_skip(pb, size);
                      break;
                  }
              }
              break;
          case MKTAG('s', 't', 'r', 'd'):
              if (stream_index >= (unsigned)s->nb_streams
                  || s->streams[stream_index]->codecpar->extradata_size
                  || s->streams[stream_index]->codecpar->codec_tag == MKTAG('H','2','6','4')) {
                  avio_skip(pb, size);
              } else {
                  uint64_t cur_pos = avio_tell(pb);
                  if (cur_pos < list_end)
                      size = FFMIN(size, list_end - cur_pos);
                  st = s->streams[stream_index];
  
                  if (size<(1<<30)) {
                      if (st->codecpar->extradata) {
                          av_log(s, AV_LOG_WARNING, "New extradata in strd chunk, freeing previous one.\n");
                      }
                      if ((ret = ff_get_extradata(s, st->codecpar, pb, size)) < 0)
                          goto fail;
                  }
  
                  if (st->codecpar->extradata_size & 1) //FIXME check if the encoder really did this correctly
                      avio_r8(pb);
  
                  ret = avi_extract_stream_metadata(s, st);
                  if (ret < 0) {
                      av_log(s, AV_LOG_WARNING, "could not decoding EXIF data in stream header.\n");
                  }
              }
              break;
          case MKTAG('i', 'n', 'd', 'x'):
              pos = avio_tell(pb);
              if ((pb->seekable & AVIO_SEEKABLE_NORMAL) && !(s->flags & AVFMT_FLAG_IGNIDX) &&
                  avi->use_odml &&
                  read_odml_index(s, 0) < 0 &&
                  (s->error_recognition & AV_EF_EXPLODE))
                  RETURN_ERROR(AVERROR_INVALIDDATA);
              avio_seek(pb, pos + size, SEEK_SET);
              break;
          case MKTAG('v', 'p', 'r', 'p'):
              if (stream_index < (unsigned)s->nb_streams && size > 9 * 4) {
                  AVRational active, active_aspect;
  
                  st = s->streams[stream_index];
                  avio_rl32(pb);
                  avio_rl32(pb);
                  avio_rl32(pb);
                  avio_rl32(pb);
                  avio_rl32(pb);
  
                  active_aspect.den = avio_rl16(pb);
                  active_aspect.num = avio_rl16(pb);
                  active.num        = avio_rl32(pb);
                  active.den        = avio_rl32(pb);
                  avio_rl32(pb); // nbFieldsPerFrame
  
                  if (active_aspect.num && active_aspect.den &&
                      active.num && active.den) {
                      st->sample_aspect_ratio = av_div_q(active_aspect, active);
                      av_log(s, AV_LOG_TRACE, "vprp %d/%d %d/%d\n",
                              active_aspect.num, active_aspect.den,
                              active.num, active.den);
                  }
                  size -= 9 * 4;
              }
              avio_skip(pb, size);
              break;
          case MKTAG('s', 't', 'r', 'n'):
              if (s->nb_streams) {
                  ret = avi_read_tag(s, s->streams[s->nb_streams - 1], tag, size);
                  if (ret < 0)
                      goto fail;
                  break;
              }
          default:
              if (size > 1000000) {
                  av_log(s, AV_LOG_ERROR,
                         "Something went wrong during header parsing, "
                         "tag %s has size %u, "
                         "I will ignore it and try to continue anyway.\n",
                         av_fourcc2str(tag), size);
                  if (s->error_recognition & AV_EF_EXPLODE)
                      RETURN_ERROR(AVERROR_INVALIDDATA);
                  avi->movi_list = avio_tell(pb) - 4;
                  avi->movi_end  = avi->fsize;
                  goto end_of_header;
              }
          /* Do not fail for very large idx1 tags */
          case MKTAG('i', 'd', 'x', '1'):
              /* skip tag */
              size += (size & 1);
              avio_skip(pb, size);
              break;
          }
      }
  
  end_of_header:
      /* check stream number */
      if (stream_index != s->nb_streams - 1) {
          RETURN_ERROR(AVERROR_INVALIDDATA);
      }
  
      if (!avi->index_loaded && (pb->seekable & AVIO_SEEKABLE_NORMAL))
          avi_load_index(s);
      calculate_bitrate(s);
      avi->index_loaded    |= 1;
  
      if ((ret = guess_ni_flag(s)) < 0)
          goto fail;
  
      avi->non_interleaved |= ret | (s->flags & AVFMT_FLAG_SORT_DTS);
  
      dict_entry = av_dict_get(s->metadata, "ISFT", NULL, 0);
      if (dict_entry && !strcmp(dict_entry->value, "PotEncoder"))
          for (i = 0; i < s->nb_streams; i++) {
              AVStream *st = s->streams[i];
              if (   st->codecpar->codec_id == AV_CODEC_ID_MPEG1VIDEO
                  || st->codecpar->codec_id == AV_CODEC_ID_MPEG2VIDEO)
                  st->need_parsing = AVSTREAM_PARSE_FULL;
          }
  
      for (i = 0; i < s->nb_streams; i++) {
          AVStream *st = s->streams[i];
          if (st->nb_index_entries)
              break;
      }
      // DV-in-AVI cannot be non-interleaved, if set this must be
      // a mis-detection.
      if (avi->dv_demux)
          avi->non_interleaved = 0;
      if (i == s->nb_streams && avi->non_interleaved) {
          av_log(s, AV_LOG_WARNING,
                 "Non-interleaved AVI without index, switching to interleaved\n");
          avi->non_interleaved = 0;
      }
  
      if (avi->non_interleaved) {
          av_log(s, AV_LOG_INFO, "non-interleaved AVI\n");
          clean_index(s);
      }
  
      ff_metadata_conv_ctx(s, NULL, avi_metadata_conv);
      ff_metadata_conv_ctx(s, NULL, ff_riff_info_conv);
  
      return 0;
  fail:
      avi_read_close(s);
      return ret;
  }
  
  static int read_gab2_sub(AVFormatContext *s, AVStream *st, AVPacket *pkt)
  {
      if (pkt->size >= 7 &&
          pkt->size < INT_MAX - AVPROBE_PADDING_SIZE &&
          !strcmp(pkt->data, "GAB2") && AV_RL16(pkt->data + 5) == 2) {
          uint8_t desc[256];
          int score      = AVPROBE_SCORE_EXTENSION, ret;
          AVIStream *ast = st->priv_data;
          ff_const59 AVInputFormat *sub_demuxer;
          AVRational time_base;
          int size;
          AVIOContext *pb = avio_alloc_context(pkt->data + 7,
                                               pkt->size - 7,
                                               0, NULL, NULL, NULL, NULL);
          AVProbeData pd;
          unsigned int desc_len = avio_rl32(pb);
  
          if (desc_len > pb->buf_end - pb->buf_ptr)
              goto error;
  
          ret = avio_get_str16le(pb, desc_len, desc, sizeof(desc));
          avio_skip(pb, desc_len - ret);
          if (*desc)
              av_dict_set(&st->metadata, "title", desc, 0);
  
          avio_rl16(pb);   /* flags? */
          avio_rl32(pb);   /* data size */
  
          size = pb->buf_end - pb->buf_ptr;
          pd = (AVProbeData) { .buf      = av_mallocz(size + AVPROBE_PADDING_SIZE),
                               .buf_size = size };
          if (!pd.buf)
              goto error;
          memcpy(pd.buf, pb->buf_ptr, size);
          sub_demuxer = av_probe_input_format2(&pd, 1, &score);
          av_freep(&pd.buf);
          if (!sub_demuxer)
              goto error;
  
          if (strcmp(sub_demuxer->name, "srt") && strcmp(sub_demuxer->name, "ass"))
              goto error;
  
          if (!(ast->sub_ctx = avformat_alloc_context()))
              goto error;
  
          ast->sub_ctx->pb = pb;
  
          if (ff_copy_whiteblacklists(ast->sub_ctx, s) < 0)
              goto error;
  
          if (!avformat_open_input(&ast->sub_ctx, "", sub_demuxer, NULL)) {
              if (ast->sub_ctx->nb_streams != 1)
                  goto error;
              ff_read_packet(ast->sub_ctx, &ast->sub_pkt);
              avcodec_parameters_copy(st->codecpar, ast->sub_ctx->streams[0]->codecpar);
              time_base = ast->sub_ctx->streams[0]->time_base;
              avpriv_set_pts_info(st, 64, time_base.num, time_base.den);
          }
          ast->sub_buffer = pkt->buf;
          pkt->buf = NULL;
          av_packet_unref(pkt);
          return 1;
  
  error:
          av_freep(&ast->sub_ctx);
          avio_context_free(&pb);
      }
      return 0;
  }
  
  static AVStream *get_subtitle_pkt(AVFormatContext *s, AVStream *next_st,
                                    AVPacket *pkt)
  {
      AVIStream *ast, *next_ast = next_st->priv_data;
      int64_t ts, next_ts, ts_min = INT64_MAX;
      AVStream *st, *sub_st = NULL;
      int i;
  
      next_ts = av_rescale_q(next_ast->frame_offset, next_st->time_base,
                             AV_TIME_BASE_Q);
  
      for (i = 0; i < s->nb_streams; i++) {
          st  = s->streams[i];
          ast = st->priv_data;
          if (st->discard < AVDISCARD_ALL && ast && ast->sub_pkt.data) {
              ts = av_rescale_q(ast->sub_pkt.dts, st->time_base, AV_TIME_BASE_Q);
              if (ts <= next_ts && ts < ts_min) {
                  ts_min = ts;
                  sub_st = st;
              }
          }
      }
  
      if (sub_st) {
          ast               = sub_st->priv_data;
          *pkt              = ast->sub_pkt;
          pkt->stream_index = sub_st->index;
  
          if (ff_read_packet(ast->sub_ctx, &ast->sub_pkt) < 0)
              ast->sub_pkt.data = NULL;
      }
      return sub_st;
  }
  
  static int get_stream_idx(const unsigned *d)
  {
      if (d[0] >= '0' && d[0] <= '9' &&
          d[1] >= '0' && d[1] <= '9') {
          return (d[0] - '0') * 10 + (d[1] - '0');
      } else {
          return 100; // invalid stream ID
      }
  }
  
  /**
   *
   * @param exit_early set to 1 to just gather packet position without making the changes needed to actually read & return the packet
   */
  static int avi_sync(AVFormatContext *s, int exit_early)
  {
      AVIContext *avi = s->priv_data;
      AVIOContext *pb = s->pb;
      int n;
      unsigned int d[8];
      unsigned int size;
      int64_t i, sync;
  
  start_sync:
      memset(d, -1, sizeof(d));
      for (i = sync = avio_tell(pb); !avio_feof(pb); i++) {
          int j;
  
          for (j = 0; j < 7; j++)
              d[j] = d[j + 1];
          d[7] = avio_r8(pb);
  
          size = d[4] + (d[5] << 8) + (d[6] << 16) + (d[7] << 24);
  
          n = get_stream_idx(d + 2);
          ff_tlog(s, "%X %X %X %X %X %X %X %X %"PRId64" %u %d\n",
                  d[0], d[1], d[2], d[3], d[4], d[5], d[6], d[7], i, size, n);
          if (i*(avi->io_fsize>0) + (uint64_t)size > avi->fsize || d[0] > 127)
              continue;
  
          // parse ix##
          if ((d[0] == 'i' && d[1] == 'x' && n < s->nb_streams) ||
              // parse JUNK
              (d[0] == 'J' && d[1] == 'U' && d[2] == 'N' && d[3] == 'K') ||
              (d[0] == 'i' && d[1] == 'd' && d[2] == 'x' && d[3] == '1') ||
              (d[0] == 'i' && d[1] == 'n' && d[2] == 'd' && d[3] == 'x')) {
              avio_skip(pb, size);
              goto start_sync;
          }
  
          // parse stray LIST
          if (d[0] == 'L' && d[1] == 'I' && d[2] == 'S' && d[3] == 'T') {
              avio_skip(pb, 4);
              goto start_sync;
          }
  
          n = get_stream_idx(d);
  
          if (!((i - avi->last_pkt_pos) & 1) &&
              get_stream_idx(d + 1) < s->nb_streams)
              continue;
  
          // detect ##ix chunk and skip
          if (d[2] == 'i' && d[3] == 'x' && n < s->nb_streams) {
              avio_skip(pb, size);
              goto start_sync;
          }
  
          if (d[2] == 'w' && d[3] == 'c' && n < s->nb_streams) {
              avio_skip(pb, 16 * 3 + 8);
              goto start_sync;
          }
  
          if (avi->dv_demux && n != 0)
              continue;
  
          // parse ##dc/##wb
          if (n < s->nb_streams) {
              AVStream *st;
              AVIStream *ast;
              st  = s->streams[n];
              ast = st->priv_data;
  
              if (!ast) {
                  av_log(s, AV_LOG_WARNING, "Skipping foreign stream %d packet\n", n);
                  continue;
              }
  
              if (s->nb_streams >= 2) {
                  AVStream *st1   = s->streams[1];
                  AVIStream *ast1 = st1->priv_data;
                  // workaround for broken small-file-bug402.avi
                  if (ast1 && d[2] == 'w' && d[3] == 'b'
                     && n == 0
                     && st ->codecpar->codec_type == AVMEDIA_TYPE_VIDEO
                     && st1->codecpar->codec_type == AVMEDIA_TYPE_AUDIO
                     && ast->prefix == 'd'*256+'c'
                     && (d[2]*256+d[3] == ast1->prefix || !ast1->prefix_count)
                    ) {
                      n   = 1;
                      st  = st1;
                      ast = ast1;
                      av_log(s, AV_LOG_WARNING,
                             "Invalid stream + prefix combination, assuming audio.\n");
                  }
              }
  
              if (d[2] == 'p' && d[3] == 'c' && size <= 4 * 256 + 4) {
                  int k    = avio_r8(pb);
                  int last = (k + avio_r8(pb) - 1) & 0xFF;
  
                  avio_rl16(pb); // flags
  
                  // b + (g << 8) + (r << 16);
                  for (; k <= last; k++)
                      ast->pal[k] = 0xFFU<<24 | avio_rb32(pb)>>8;
  
                  ast->has_pal = 1;
                  goto start_sync;
              } else if (((ast->prefix_count < 5 || sync + 9 > i) &&
                          d[2] < 128 && d[3] < 128) ||
                         d[2] * 256 + d[3] == ast->prefix /* ||
                         (d[2] == 'd' && d[3] == 'c') ||
                         (d[2] == 'w' && d[3] == 'b') */) {
                  if (exit_early)
                      return 0;
                  if (d[2] * 256 + d[3] == ast->prefix)
                      ast->prefix_count++;
                  else {
                      ast->prefix       = d[2] * 256 + d[3];
                      ast->prefix_count = 0;
                  }
  
                  if (!avi->dv_demux &&
                      ((st->discard >= AVDISCARD_DEFAULT && size == 0) /* ||
                          // FIXME: needs a little reordering
                          (st->discard >= AVDISCARD_NONKEY &&
                          !(pkt->flags & AV_PKT_FLAG_KEY)) */
                      || st->discard >= AVDISCARD_ALL)) {
  
                      ast->frame_offset += get_duration(ast, size);
                      avio_skip(pb, size);
                      goto start_sync;
                  }
  
                  avi->stream_index = n;
                  ast->packet_size  = size + 8;
                  ast->remaining    = size;
  
                  if (size) {
                      uint64_t pos = avio_tell(pb) - 8;
                      if (!st->index_entries || !st->nb_index_entries ||
                          st->index_entries[st->nb_index_entries - 1].pos < pos) {
                          av_add_index_entry(st, pos, ast->frame_offset, size,
                                             0, AVINDEX_KEYFRAME);
                      }
                  }
                  return 0;
              }
          }
      }
  
      if (pb->error)
          return pb->error;
      return AVERROR_EOF;
  }
  
  static int ni_prepare_read(AVFormatContext *s)
  {
      AVIContext *avi = s->priv_data;
      int best_stream_index = 0;
      AVStream *best_st     = NULL;
      AVIStream *best_ast;
      int64_t best_ts = INT64_MAX;
      int i;
  
      for (i = 0; i < s->nb_streams; i++) {
          AVStream *st   = s->streams[i];
          AVIStream *ast = st->priv_data;
          int64_t ts     = ast->frame_offset;
          int64_t last_ts;
  
          if (!st->nb_index_entries)
              continue;
  
          last_ts = st->index_entries[st->nb_index_entries - 1].timestamp;
          if (!ast->remaining && ts > last_ts)
              continue;
  
          ts = av_rescale_q(ts, st->time_base,
                            (AVRational) { FFMAX(1, ast->sample_size),
                                           AV_TIME_BASE });
  
          av_log(s, AV_LOG_TRACE, "%"PRId64" %d/%d %"PRId64"\n", ts,
                  st->time_base.num, st->time_base.den, ast->frame_offset);
          if (ts < best_ts) {
              best_ts           = ts;
              best_st           = st;
              best_stream_index = i;
          }
      }
      if (!best_st)
          return AVERROR_EOF;
  
      best_ast = best_st->priv_data;
      best_ts  = best_ast->frame_offset;
      if (best_ast->remaining) {
          i = av_index_search_timestamp(best_st,
                                        best_ts,
                                        AVSEEK_FLAG_ANY |
                                        AVSEEK_FLAG_BACKWARD);
      } else {
          i = av_index_search_timestamp(best_st, best_ts, AVSEEK_FLAG_ANY);
          if (i >= 0)
              best_ast->frame_offset = best_st->index_entries[i].timestamp;
      }
  
      if (i >= 0) {
          int64_t pos = best_st->index_entries[i].pos;
          pos += best_ast->packet_size - best_ast->remaining;
          if (avio_seek(s->pb, pos + 8, SEEK_SET) < 0)
            return AVERROR_EOF;
  
          av_assert0(best_ast->remaining <= best_ast->packet_size);
  
          avi->stream_index = best_stream_index;
          if (!best_ast->remaining)
              best_ast->packet_size =
              best_ast->remaining   = best_st->index_entries[i].size;
      }
      else
          return AVERROR_EOF;
  
      return 0;
  }
  
  static int avi_read_packet(AVFormatContext *s, AVPacket *pkt)
  {
      AVIContext *avi = s->priv_data;
      AVIOContext *pb = s->pb;
      int err;
  
      if (CONFIG_DV_DEMUXER && avi->dv_demux) {
          int size = avpriv_dv_get_packet(avi->dv_demux, pkt);
          if (size >= 0)
              return size;
          else
              goto resync;
      }
  
      if (avi->non_interleaved) {
          err = ni_prepare_read(s);
          if (err < 0)
              return err;
      }
  
  resync:
      if (avi->stream_index >= 0) {
          AVStream *st   = s->streams[avi->stream_index];
          AVIStream *ast = st->priv_data;
          int dv_demux = CONFIG_DV_DEMUXER && avi->dv_demux;
          int size, err;
  
          if (get_subtitle_pkt(s, st, pkt))
              return 0;
  
          // minorityreport.AVI block_align=1024 sample_size=1 IMA-ADPCM
          if (ast->sample_size <= 1)
              size = INT_MAX;
          else if (ast->sample_size < 32)
              // arbitrary multiplier to avoid tiny packets for raw PCM data
              size = 1024 * ast->sample_size;
          else
              size = ast->sample_size;
  
          if (size > ast->remaining)
              size = ast->remaining;
          avi->last_pkt_pos = avio_tell(pb);
          err               = av_get_packet(pb, pkt, size);
          if (err < 0)
              return err;
          size = err;
  
          if (ast->has_pal && pkt->size < (unsigned)INT_MAX / 2 && !dv_demux) {
              uint8_t *pal;
              pal = av_packet_new_side_data(pkt,
                                            AV_PKT_DATA_PALETTE,
                                            AVPALETTE_SIZE);
              if (!pal) {
                  av_log(s, AV_LOG_ERROR,
                         "Failed to allocate data for palette\n");
              } else {
                  memcpy(pal, ast->pal, AVPALETTE_SIZE);
                  ast->has_pal = 0;
              }
          }
  
          if (dv_demux) {
              AVBufferRef *avbuf = pkt->buf;
              size = avpriv_dv_produce_packet(avi->dv_demux, pkt,
                                              pkt->data, pkt->size, pkt->pos);
              pkt->buf    = avbuf;
              pkt->flags |= AV_PKT_FLAG_KEY;
              if (size < 0)
                  av_packet_unref(pkt);
          } else if (st->codecpar->codec_type == AVMEDIA_TYPE_SUBTITLE &&
                     !st->codecpar->codec_tag && read_gab2_sub(s, st, pkt)) {
              ast->frame_offset++;
              avi->stream_index = -1;
              ast->remaining    = 0;
              goto resync;
          } else {
              /* XXX: How to handle B-frames in AVI? */
              pkt->dts = ast->frame_offset;
  //                pkt->dts += ast->start;
              if (ast->sample_size)
                  pkt->dts /= ast->sample_size;
              pkt->stream_index = avi->stream_index;
  
              if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO && st->index_entries) {
                  AVIndexEntry *e;
                  int index;
  
                  index = av_index_search_timestamp(st, ast->frame_offset, AVSEEK_FLAG_ANY);
                  e     = &st->index_entries[index];
  
                  if (index >= 0 && e->timestamp == ast->frame_offset) {
                      if (index == st->nb_index_entries-1) {
                          int key=1;
                          uint32_t state=-1;
                          if (st->codecpar->codec_id == AV_CODEC_ID_MPEG4) {
                              const uint8_t *ptr = pkt->data, *end = ptr + FFMIN(size, 256);
                              while (ptr < end) {
                                  ptr = avpriv_find_start_code(ptr, end, &state);
                                  if (state == 0x1B6 && ptr < end) {
                                      key = !(*ptr & 0xC0);
                                      break;
                                  }
                              }
                          }
                          if (!key)
                              e->flags &= ~AVINDEX_KEYFRAME;
                      }
                      if (e->flags & AVINDEX_KEYFRAME)
                          pkt->flags |= AV_PKT_FLAG_KEY;
                  }
              } else {
                  pkt->flags |= AV_PKT_FLAG_KEY;
              }
              ast->frame_offset += get_duration(ast, pkt->size);
          }
          ast->remaining -= err;
          if (!ast->remaining) {
              avi->stream_index = -1;
              ast->packet_size  = 0;
          }
  
          if (!avi->non_interleaved && pkt->pos >= 0 && ast->seek_pos > pkt->pos) {
              av_packet_unref(pkt);
              goto resync;
          }
          ast->seek_pos= 0;
  
          if (!avi->non_interleaved && st->nb_index_entries>1 && avi->index_loaded>1) {
              int64_t dts= av_rescale_q(pkt->dts, st->time_base, AV_TIME_BASE_Q);
  
              if (avi->dts_max < dts) {
                  avi->dts_max = dts;
              } else if (avi->dts_max - (uint64_t)dts > 2*AV_TIME_BASE) {
                  avi->non_interleaved= 1;
                  av_log(s, AV_LOG_INFO, "Switching to NI mode, due to poor interleaving\n");
              }
          }
  
          return 0;
      }
  
      if ((err = avi_sync(s, 0)) < 0)
          return err;
      goto resync;
  }
  
  /* XXX: We make the implicit supposition that the positions are sorted
   * for each stream. */
  static int avi_read_idx1(AVFormatContext *s, int size)
  {
      AVIContext *avi = s->priv_data;
      AVIOContext *pb = s->pb;
      int nb_index_entries, i;
      AVStream *st;
      AVIStream *ast;
      int64_t pos;
      unsigned int index, tag, flags, len, first_packet = 1;
      int64_t last_pos = -1;
      unsigned last_idx = -1;
      int64_t idx1_pos, first_packet_pos = 0, data_offset = 0;
      int anykey = 0;
  
      nb_index_entries = size / 16;
      if (nb_index_entries <= 0)
          return AVERROR_INVALIDDATA;
  
      idx1_pos = avio_tell(pb);
      avio_seek(pb, avi->movi_list + 4, SEEK_SET);
      if (avi_sync(s, 1) == 0)
          first_packet_pos = avio_tell(pb) - 8;
      avi->stream_index = -1;
      avio_seek(pb, idx1_pos, SEEK_SET);
  
      if (s->nb_streams == 1 && s->streams[0]->codecpar->codec_tag == AV_RL32("MMES")) {
          first_packet_pos = 0;
          data_offset = avi->movi_list;
      }
  
      /* Read the entries and sort them in each stream component. */
      for (i = 0; i < nb_index_entries; i++) {
          if (avio_feof(pb))
              return -1;
  
          tag   = avio_rl32(pb);
          flags = avio_rl32(pb);
          pos   = avio_rl32(pb);
          len   = avio_rl32(pb);
          av_log(s, AV_LOG_TRACE, "%d: tag=0x%x flags=0x%x pos=0x%"PRIx64" len=%d/",
                  i, tag, flags, pos, len);
  
          index  = ((tag      & 0xff) - '0') * 10;
          index +=  (tag >> 8 & 0xff) - '0';
          if (index >= s->nb_streams)
              continue;
          st  = s->streams[index];
          ast = st->priv_data;
  
          /* Skip 'xxpc' palette change entries in the index until a logic
           * to process these is properly implemented. */
          if ((tag >> 16 & 0xff) == 'p' && (tag >> 24 & 0xff) == 'c')
              continue;
  
          if (first_packet && first_packet_pos) {
              if (avi->movi_list + 4 != pos || pos + 500 > first_packet_pos)
                  data_offset  = first_packet_pos - pos;
              first_packet = 0;
          }
          pos += data_offset;
  
          av_log(s, AV_LOG_TRACE, "%d cum_len=%"PRId64"\n", len, ast->cum_len);
  
          // even if we have only a single stream, we should
          // switch to non-interleaved to get correct timestamps
          if (last_pos == pos)
              avi->non_interleaved = 1;
          if (last_idx != pos && len) {
              av_add_index_entry(st, pos, ast->cum_len, len, 0,
                                 (flags & AVIIF_INDEX) ? AVINDEX_KEYFRAME : 0);
              last_idx= pos;
          }
          ast->cum_len += get_duration(ast, len);
          last_pos      = pos;
          anykey       |= flags&AVIIF_INDEX;
      }
      if (!anykey) {
          for (index = 0; index < s->nb_streams; index++) {
              st = s->streams[index];
              if (st->nb_index_entries)
                  st->index_entries[0].flags |= AVINDEX_KEYFRAME;
          }
      }
      return 0;
  }
  
  /* Scan the index and consider any file with streams more than
   * 2 seconds or 64MB apart non-interleaved. */
  static int check_stream_max_drift(AVFormatContext *s)
  {
      int64_t min_pos, pos;
      int i;
      int *idx = av_mallocz_array(s->nb_streams, sizeof(*idx));
      if (!idx)
          return AVERROR(ENOMEM);
      for (min_pos = pos = 0; min_pos != INT64_MAX; pos = min_pos + 1LU) {
          int64_t max_dts = INT64_MIN / 2;
          int64_t min_dts = INT64_MAX / 2;
          int64_t max_buffer = 0;
  
          min_pos = INT64_MAX;
  
          for (i = 0; i < s->nb_streams; i++) {
              AVStream *st = s->streams[i];
              AVIStream *ast = st->priv_data;
              int n = st->nb_index_entries;
              while (idx[i] < n && st->index_entries[idx[i]].pos < pos)
                  idx[i]++;
              if (idx[i] < n) {
                  int64_t dts;
                  dts = av_rescale_q(st->index_entries[idx[i]].timestamp /
                                     FFMAX(ast->sample_size, 1),
                                     st->time_base, AV_TIME_BASE_Q);
                  min_dts = FFMIN(min_dts, dts);
                  min_pos = FFMIN(min_pos, st->index_entries[idx[i]].pos);
              }
          }
          for (i = 0; i < s->nb_streams; i++) {
              AVStream *st = s->streams[i];
              AVIStream *ast = st->priv_data;
  
              if (idx[i] && min_dts != INT64_MAX / 2) {
                  int64_t dts;
                  dts = av_rescale_q(st->index_entries[idx[i] - 1].timestamp /
                                     FFMAX(ast->sample_size, 1),
                                     st->time_base, AV_TIME_BASE_Q);
                  max_dts = FFMAX(max_dts, dts);
                  max_buffer = FFMAX(max_buffer,
                                     av_rescale(dts - min_dts,
                                                st->codecpar->bit_rate,
                                                AV_TIME_BASE));
              }
          }
          if (max_dts - min_dts > 2 * AV_TIME_BASE ||
              max_buffer > 1024 * 1024 * 8 * 8) {
              av_free(idx);
              return 1;
          }
      }
      av_free(idx);
      return 0;
  }
  
  static int guess_ni_flag(AVFormatContext *s)
  {
      int i;
      int64_t last_start = 0;
      int64_t first_end  = INT64_MAX;
      int64_t oldpos     = avio_tell(s->pb);
  
      for (i = 0; i < s->nb_streams; i++) {
          AVStream *st = s->streams[i];
          int n        = st->nb_index_entries;
          unsigned int size;
  
          if (n <= 0)
              continue;
  
          if (n >= 2) {
              int64_t pos = st->index_entries[0].pos;
              unsigned tag[2];
              avio_seek(s->pb, pos, SEEK_SET);
              tag[0] = avio_r8(s->pb);
              tag[1] = avio_r8(s->pb);
              avio_rl16(s->pb);
              size = avio_rl32(s->pb);
              if (get_stream_idx(tag) == i && pos + size > st->index_entries[1].pos)
                  last_start = INT64_MAX;
              if (get_stream_idx(tag) == i && size == st->index_entries[0].size + 8)
                  last_start = INT64_MAX;
          }
  
          if (st->index_entries[0].pos > last_start)
              last_start = st->index_entries[0].pos;
          if (st->index_entries[n - 1].pos < first_end)
              first_end = st->index_entries[n - 1].pos;
      }
      avio_seek(s->pb, oldpos, SEEK_SET);
  
      if (last_start > first_end)
          return 1;
  
      return check_stream_max_drift(s);
  }
  
  static int avi_load_index(AVFormatContext *s)
  {
      AVIContext *avi = s->priv_data;
      AVIOContext *pb = s->pb;
      uint32_t tag, size;
      int64_t pos = avio_tell(pb);
      int64_t next;
      int ret     = -1;
  
      if (avio_seek(pb, avi->movi_end, SEEK_SET) < 0)
          goto the_end; // maybe truncated file
      av_log(s, AV_LOG_TRACE, "movi_end=0x%"PRIx64"\n", avi->movi_end);
      for (;;) {
          tag  = avio_rl32(pb);
          size = avio_rl32(pb);
          if (avio_feof(pb))
              break;
          next = avio_tell(pb);
          if (next < 0 || next > INT64_MAX - size - (size & 1))
              break;
          next += size + (size & 1LL);
  
          if (tag == MKTAG('i', 'd', 'x', '1') &&
              avi_read_idx1(s, size) >= 0) {
              avi->index_loaded=2;
              ret = 0;
          }else if (tag == MKTAG('L', 'I', 'S', 'T')) {
              uint32_t tag1 = avio_rl32(pb);
  
              if (tag1 == MKTAG('I', 'N', 'F', 'O'))
                  ff_read_riff_info(s, size - 4);
          }else if (!ret)
              break;
  
          if (avio_seek(pb, next, SEEK_SET) < 0)
              break; // something is wrong here
      }
  
  the_end:
      avio_seek(pb, pos, SEEK_SET);
      return ret;
  }
  
  static void seek_subtitle(AVStream *st, AVStream *st2, int64_t timestamp)
  {
      AVIStream *ast2 = st2->priv_data;
      int64_t ts2     = av_rescale_q(timestamp, st->time_base, st2->time_base);
      av_packet_unref(&ast2->sub_pkt);
      if (avformat_seek_file(ast2->sub_ctx, 0, INT64_MIN, ts2, ts2, 0) >= 0 ||
          avformat_seek_file(ast2->sub_ctx, 0, ts2, ts2, INT64_MAX, 0) >= 0)
          ff_read_packet(ast2->sub_ctx, &ast2->sub_pkt);
  }
  
  static int avi_read_seek(AVFormatContext *s, int stream_index,
                           int64_t timestamp, int flags)
  {
      AVIContext *avi = s->priv_data;
      AVStream *st;
      int i, index;
      int64_t pos, pos_min;
      AVIStream *ast;
  
      /* Does not matter which stream is requested dv in avi has the
       * stream information in the first video stream.
       */
      if (avi->dv_demux)
          stream_index = 0;
  
      if (!avi->index_loaded) {
          /* we only load the index on demand */
          avi_load_index(s);
          avi->index_loaded |= 1;
      }
      av_assert0(stream_index >= 0);
  
      st    = s->streams[stream_index];
      ast   = st->priv_data;
      index = av_index_search_timestamp(st,
                                        timestamp * FFMAX(ast->sample_size, 1),
                                        flags);
      if (index < 0) {
          if (st->nb_index_entries > 0)
              av_log(s, AV_LOG_DEBUG, "Failed to find timestamp %"PRId64 " in index %"PRId64 " .. %"PRId64 "\n",
                     timestamp * FFMAX(ast->sample_size, 1),
                     st->index_entries[0].timestamp,
                     st->index_entries[st->nb_index_entries - 1].timestamp);
          return AVERROR_INVALIDDATA;
      }
  
      /* find the position */
      pos       = st->index_entries[index].pos;
      timestamp = st->index_entries[index].timestamp / FFMAX(ast->sample_size, 1);
  
      av_log(s, AV_LOG_TRACE, "XX %"PRId64" %d %"PRId64"\n",
              timestamp, index, st->index_entries[index].timestamp);
  
      if (CONFIG_DV_DEMUXER && avi->dv_demux) {
          /* One and only one real stream for DV in AVI, and it has video  */
          /* offsets. Calling with other stream indexes should have failed */
          /* the av_index_search_timestamp call above.                     */
  
          if (avio_seek(s->pb, pos, SEEK_SET) < 0)
              return -1;
  
          /* Feed the DV video stream version of the timestamp to the */
          /* DV demux so it can synthesize correct timestamps.        */
          ff_dv_offset_reset(avi->dv_demux, timestamp);
  
          avi->stream_index = -1;
          return 0;
      }
  
      pos_min = pos;
      for (i = 0; i < s->nb_streams; i++) {
          AVStream *st2   = s->streams[i];
          AVIStream *ast2 = st2->priv_data;
  
          ast2->packet_size =
          ast2->remaining   = 0;
  
          if (ast2->sub_ctx) {
              seek_subtitle(st, st2, timestamp);
              continue;
          }
  
          if (st2->nb_index_entries <= 0)
              continue;
  
  //        av_assert1(st2->codecpar->block_align);
          index = av_index_search_timestamp(st2,
                                            av_rescale_q(timestamp,
                                                         st->time_base,
                                                         st2->time_base) *
                                            FFMAX(ast2->sample_size, 1),
                                            flags |
                                            AVSEEK_FLAG_BACKWARD |
                                            (st2->codecpar->codec_type != AVMEDIA_TYPE_VIDEO ? AVSEEK_FLAG_ANY : 0));
          if (index < 0)
              index = 0;
          ast2->seek_pos = st2->index_entries[index].pos;
          pos_min = FFMIN(pos_min,ast2->seek_pos);
      }
      for (i = 0; i < s->nb_streams; i++) {
          AVStream *st2 = s->streams[i];
          AVIStream *ast2 = st2->priv_data;
  
          if (ast2->sub_ctx || st2->nb_index_entries <= 0)
              continue;
  
          index = av_index_search_timestamp(
                  st2,
                  av_rescale_q(timestamp, st->time_base, st2->time_base) * FFMAX(ast2->sample_size, 1),
                  flags | AVSEEK_FLAG_BACKWARD | (st2->codecpar->codec_type != AVMEDIA_TYPE_VIDEO ? AVSEEK_FLAG_ANY : 0));
          if (index < 0)
              index = 0;
          while (!avi->non_interleaved && index>0 && st2->index_entries[index-1].pos >= pos_min)
              index--;
          ast2->frame_offset = st2->index_entries[index].timestamp;
      }
  
      /* do the seek */
      if (avio_seek(s->pb, pos_min, SEEK_SET) < 0) {
          av_log(s, AV_LOG_ERROR, "Seek failed\n");
          return -1;
      }
      avi->stream_index = -1;
      avi->dts_max      = INT_MIN;
      return 0;
  }
  
  static int avi_read_close(AVFormatContext *s)
  {
      int i;
      AVIContext *avi = s->priv_data;
  
      for (i = 0; i < s->nb_streams; i++) {
          AVStream *st   = s->streams[i];
          AVIStream *ast = st->priv_data;
          if (ast) {
              if (ast->sub_ctx) {
                  av_freep(&ast->sub_ctx->pb);
                  avformat_close_input(&ast->sub_ctx);
              }
              av_buffer_unref(&ast->sub_buffer);
              av_packet_unref(&ast->sub_pkt);
          }
      }
  
      av_freep(&avi->dv_demux);
  
      return 0;
  }
  
  static int avi_probe(const AVProbeData *p)
  {
      int i;
  
      /* check file header */
      for (i = 0; avi_headers[i][0]; i++)
          if (AV_RL32(p->buf    ) == AV_RL32(avi_headers[i]    ) &&
              AV_RL32(p->buf + 8) == AV_RL32(avi_headers[i] + 4))
              return AVPROBE_SCORE_MAX;
  
      return 0;
  }
  
  AVInputFormat ff_avi_demuxer = {
      .name           = "avi",
      .long_name      = NULL_IF_CONFIG_SMALL("AVI (Audio Video Interleaved)"),
      .priv_data_size = sizeof(AVIContext),
      .extensions     = "avi",
      .read_probe     = avi_probe,
      .read_header    = avi_read_header,
      .read_packet    = avi_read_packet,
      .read_close     = avi_read_close,
      .read_seek      = avi_read_seek,
      .priv_class = &demuxer_class,
  };
  