text: /*
   * MPEG-1/2 demuxer
   * Copyright (c) 2000, 2001, 2002 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 "avformat.h"
  #include "avio_internal.h"
  #include "internal.h"
  #include "mpeg.h"
  
  /*********************************************/
  /* demux code */
  
  #define MAX_SYNC_SIZE 100000
  
  static int check_pes(const uint8_t *p, const uint8_t *end)
  {
      int pes1;
      int pes2 = (p[3] & 0xC0) == 0x80 &&
                 (p[4] & 0xC0) != 0x40 &&
                 ((p[4] & 0xC0) == 0x00 ||
                  (p[4] & 0xC0) >> 2 == (p[6] & 0xF0));
  
      for (p += 3; p < end && *p == 0xFF; p++) ;
      if ((*p & 0xC0) == 0x40)
          p += 2;
  
      if ((*p & 0xF0) == 0x20)
          pes1 = p[0] & p[2] & p[4] & 1;
      else if ((*p & 0xF0) == 0x30)
          pes1 = p[0] & p[2] & p[4] & p[5] & p[7] & p[9] & 1;
      else
          pes1 = *p == 0x0F;
  
      return pes1 || pes2;
  }
  
  static int check_pack_header(const uint8_t *buf)
  {
      return (buf[1] & 0xC0) == 0x40 || (buf[1] & 0xF0) == 0x20;
  }
  
  static int mpegps_probe(const AVProbeData *p)
  {
      uint32_t code = -1;
      int i;
      int sys = 0, pspack = 0, priv1 = 0, vid = 0;
      int audio = 0, invalid = 0, score = 0;
      int endpes = 0;
  
      for (i = 0; i < p->buf_size; i++) {
          code = (code << 8) + p->buf[i];
          if ((code & 0xffffff00) == 0x100) {
              int len  = p->buf[i + 1] << 8 | p->buf[i + 2];
              int pes  = endpes <= i && check_pes(p->buf + i, p->buf + p->buf_size);
              int pack = check_pack_header(p->buf + i);
  
              if (code == SYSTEM_HEADER_START_CODE)
                  sys++;
              else if (code == PACK_START_CODE && pack)
                  pspack++;
              else if ((code & 0xf0) == VIDEO_ID && pes) {
                  endpes = i + len;
                  vid++;
              }
              // skip pes payload to avoid start code emulation for private
              // and audio streams
              else if ((code & 0xe0) == AUDIO_ID &&  pes) {audio++; i+=len;}
              else if (code == PRIVATE_STREAM_1  &&  pes) {priv1++; i+=len;}
              else if (code == 0x1fd             &&  pes) vid++; //VC1
  
              else if ((code & 0xf0) == VIDEO_ID && !pes) invalid++;
              else if ((code & 0xe0) == AUDIO_ID && !pes) invalid++;
              else if (code == PRIVATE_STREAM_1  && !pes) invalid++;
          }
      }
  
      if (vid + audio > invalid + 1) /* invalid VDR files nd short PES streams */
          score = AVPROBE_SCORE_EXTENSION / 2;
  
  //     av_log(NULL, AV_LOG_ERROR, "vid:%d aud:%d sys:%d pspack:%d invalid:%d size:%d \n",
  //            vid, audio, sys, pspack, invalid, p->buf_size);
  
      if (sys > invalid && sys * 9 <= pspack * 10)
          return (audio > 12 || vid > 3 || pspack > 2) ? AVPROBE_SCORE_EXTENSION + 2
                                                       : AVPROBE_SCORE_EXTENSION / 2 + (audio + vid + pspack > 1); // 1 more than mp3
      if (pspack > invalid && (priv1 + vid + audio) * 10 >= pspack * 9)
          return pspack > 2 ? AVPROBE_SCORE_EXTENSION + 2
                            : AVPROBE_SCORE_EXTENSION / 2; // 1 more than .mpg
      if ((!!vid ^ !!audio) && (audio > 4 || vid > 1) && !sys &&
          !pspack && p->buf_size > 2048 && vid + audio > invalid) /* PES stream */
          return (audio > 12 || vid > 6 + 2 * invalid) ? AVPROBE_SCORE_EXTENSION + 2
                                                       : AVPROBE_SCORE_EXTENSION / 2;
  
      // 02-Penguin.flac has sys:0 priv1:0 pspack:0 vid:0 audio:1
      // mp3_misidentified_2.mp3 has sys:0 priv1:0 pspack:0 vid:0 audio:6
      // Have\ Yourself\ a\ Merry\ Little\ Christmas.mp3 0 0 0 5 0 1 len:21618
      return score;
  }
  
  typedef struct MpegDemuxContext {
      int32_t header_state;
      unsigned char psm_es_type[256];
      int sofdec;
      int dvd;
      int imkh_cctv;
      int raw_ac3;
  } MpegDemuxContext;
  
  static int mpegps_read_header(AVFormatContext *s)
  {
      MpegDemuxContext *m = s->priv_data;
      char buffer[7] = { 0 };
      int64_t last_pos = avio_tell(s->pb);
  
      m->header_state = 0xff;
      s->ctx_flags   |= AVFMTCTX_NOHEADER;
  
      avio_get_str(s->pb, 6, buffer, sizeof(buffer));
      if (!memcmp("IMKH", buffer, 4)) {
          m->imkh_cctv = 1;
      } else if (!memcmp("Sofdec", buffer, 6)) {
          m->sofdec = 1;
      } else
         avio_seek(s->pb, last_pos, SEEK_SET);
  
      /* no need to do more */
      return 0;
  }
  
  static int64_t get_pts(AVIOContext *pb, int c)
  {
      uint8_t buf[5];
      int ret;
  
      buf[0] = c < 0 ? avio_r8(pb) : c;
      ret = avio_read(pb, buf + 1, 4);
      if (ret < 4)
          return AV_NOPTS_VALUE;
  
      return ff_parse_pes_pts(buf);
  }
  
  static int find_next_start_code(AVIOContext *pb, int *size_ptr,
                                  int32_t *header_state)
  {
      unsigned int state, v;
      int val, n;
  
      state = *header_state;
      n     = *size_ptr;
      while (n > 0) {
          if (avio_feof(pb))
              break;
          v = avio_r8(pb);
          n--;
          if (state == 0x000001) {
              state = ((state << 8) | v) & 0xffffff;
              val   = state;
              goto found;
          }
          state = ((state << 8) | v) & 0xffffff;
      }
      val = -1;
  
  found:
      *header_state = state;
      *size_ptr     = n;
      return val;
  }
  
  /**
   * Extract stream types from a program stream map
   * According to ISO/IEC 13818-1 ('MPEG-2 Systems') table 2-35
   *
   * @return number of bytes occupied by PSM in the bitstream
   */
  static long mpegps_psm_parse(MpegDemuxContext *m, AVIOContext *pb)
  {
      int psm_length, ps_info_length, es_map_length;
  
      psm_length = avio_rb16(pb);
      avio_r8(pb);
      avio_r8(pb);
      ps_info_length = avio_rb16(pb);
  
      /* skip program_stream_info */
      avio_skip(pb, ps_info_length);
      /*es_map_length = */avio_rb16(pb);
      /* Ignore es_map_length, trust psm_length */
      es_map_length = psm_length - ps_info_length - 10;
  
      /* at least one es available? */
      while (es_map_length >= 4) {
          unsigned char type      = avio_r8(pb);
          unsigned char es_id     = avio_r8(pb);
          uint16_t es_info_length = avio_rb16(pb);
  
          /* remember mapping from stream id to stream type */
          m->psm_es_type[es_id] = type;
          /* skip program_stream_info */
          avio_skip(pb, es_info_length);
          es_map_length -= 4 + es_info_length;
      }
      avio_rb32(pb); /* crc32 */
      return 2 + psm_length;
  }
  
  /* read the next PES header. Return its position in ppos
   * (if not NULL), and its start code, pts and dts.
   */
  static int mpegps_read_pes_header(AVFormatContext *s,
                                    int64_t *ppos, int *pstart_code,
                                    int64_t *ppts, int64_t *pdts)
  {
      MpegDemuxContext *m = s->priv_data;
      int len, size, startcode, c, flags, header_len;
      int pes_ext, ext2_len, id_ext, skip;
      int64_t pts, dts;
      int64_t last_sync = avio_tell(s->pb);
  
  error_redo:
      avio_seek(s->pb, last_sync, SEEK_SET);
  redo:
      /* next start code (should be immediately after) */
      m->header_state = 0xff;
      size      = MAX_SYNC_SIZE;
      startcode = find_next_start_code(s->pb, &size, &m->header_state);
      last_sync = avio_tell(s->pb);
      if (startcode < 0) {
          if (avio_feof(s->pb))
              return AVERROR_EOF;
          // FIXME we should remember header_state
          return FFERROR_REDO;
      }
  
      if (startcode == PACK_START_CODE)
          goto redo;
      if (startcode == SYSTEM_HEADER_START_CODE)
          goto redo;
      if (startcode == PADDING_STREAM) {
          avio_skip(s->pb, avio_rb16(s->pb));
          goto redo;
      }
      if (startcode == PRIVATE_STREAM_2) {
          if (!m->sofdec) {
              /* Need to detect whether this from a DVD or a 'Sofdec' stream */
              int len = avio_rb16(s->pb);
              int bytesread = 0;
              uint8_t *ps2buf = av_malloc(len);
  
              if (ps2buf) {
                  bytesread = avio_read(s->pb, ps2buf, len);
  
                  if (bytesread != len) {
                      avio_skip(s->pb, len - bytesread);
                  } else {
                      uint8_t *p = 0;
                      if (len >= 6)
                          p = memchr(ps2buf, 'S', len - 5);
  
                      if (p)
                          m->sofdec = !memcmp(p+1, "ofdec", 5);
  
                      m->sofdec -= !m->sofdec;
  
                      if (m->sofdec < 0) {
                          if (len == 980  && ps2buf[0] == 0) {
                              /* PCI structure? */
                              uint32_t startpts = AV_RB32(ps2buf + 0x0d);
                              uint32_t endpts = AV_RB32(ps2buf + 0x11);
                              uint8_t hours = ((ps2buf[0x19] >> 4) * 10) + (ps2buf[0x19] & 0x0f);
                              uint8_t mins  = ((ps2buf[0x1a] >> 4) * 10) + (ps2buf[0x1a] & 0x0f);
                              uint8_t secs  = ((ps2buf[0x1b] >> 4) * 10) + (ps2buf[0x1b] & 0x0f);
  
                              m->dvd = (hours <= 23 &&
                                        mins  <= 59 &&
                                        secs  <= 59 &&
                                        (ps2buf[0x19] & 0x0f) < 10 &&
                                        (ps2buf[0x1a] & 0x0f) < 10 &&
                                        (ps2buf[0x1b] & 0x0f) < 10 &&
                                        endpts >= startpts);
                          } else if (len == 1018 && ps2buf[0] == 1) {
                              /* DSI structure? */
                              uint8_t hours = ((ps2buf[0x1d] >> 4) * 10) + (ps2buf[0x1d] & 0x0f);
                              uint8_t mins  = ((ps2buf[0x1e] >> 4) * 10) + (ps2buf[0x1e] & 0x0f);
                              uint8_t secs  = ((ps2buf[0x1f] >> 4) * 10) + (ps2buf[0x1f] & 0x0f);
  
                              m->dvd = (hours <= 23 &&
                                        mins  <= 59 &&
                                        secs  <= 59 &&
                                        (ps2buf[0x1d] & 0x0f) < 10 &&
                                        (ps2buf[0x1e] & 0x0f) < 10 &&
                                        (ps2buf[0x1f] & 0x0f) < 10);
                          }
                      }
                  }
  
                  av_free(ps2buf);
  
                  /* If this isn't a DVD packet or no memory
                   * could be allocated, just ignore it.
                   * If we did, move back to the start of the
                   * packet (plus 'length' field) */
                  if (!m->dvd || avio_skip(s->pb, -(len + 2)) < 0) {
                      /* Skip back failed.
                       * This packet will be lost but that can't be helped
                       * if we can't skip back
                       */
                      goto redo;
                  }
              } else {
                  /* No memory */
                  avio_skip(s->pb, len);
                  goto redo;
              }
          } else if (!m->dvd) {
              int len = avio_rb16(s->pb);
              avio_skip(s->pb, len);
              goto redo;
          }
      }
      if (startcode == PROGRAM_STREAM_MAP) {
          mpegps_psm_parse(m, s->pb);
          goto redo;
      }
  
      /* find matching stream */
      if (!((startcode >= 0x1c0 && startcode <= 0x1df) ||
            (startcode >= 0x1e0 && startcode <= 0x1ef) ||
            (startcode == 0x1bd) ||
            (startcode == PRIVATE_STREAM_2) ||
            (startcode == 0x1fd)))
          goto redo;
      if (ppos) {
          *ppos = avio_tell(s->pb) - 4;
      }
      len = avio_rb16(s->pb);
      pts =
      dts = AV_NOPTS_VALUE;
      if (startcode != PRIVATE_STREAM_2)
      {
      /* stuffing */
      for (;;) {
          if (len < 1)
              goto error_redo;
          c = avio_r8(s->pb);
          len--;
          /* XXX: for MPEG-1, should test only bit 7 */
          if (c != 0xff)
              break;
      }
      if ((c & 0xc0) == 0x40) {
          /* buffer scale & size */
          avio_r8(s->pb);
          c    = avio_r8(s->pb);
          len -= 2;
      }
      if ((c & 0xe0) == 0x20) {
          dts  =
          pts  = get_pts(s->pb, c);
          len -= 4;
          if (c & 0x10) {
              dts  = get_pts(s->pb, -1);
              len -= 5;
          }
      } else if ((c & 0xc0) == 0x80) {
          /* mpeg 2 PES */
          flags      = avio_r8(s->pb);
          header_len = avio_r8(s->pb);
          len       -= 2;
          if (header_len > len)
              goto error_redo;
          len -= header_len;
          if (flags & 0x80) {
              dts         = pts = get_pts(s->pb, -1);
              header_len -= 5;
              if (flags & 0x40) {
                  dts         = get_pts(s->pb, -1);
                  header_len -= 5;
              }
          }
          if (flags & 0x3f && header_len == 0) {
              flags &= 0xC0;
              av_log(s, AV_LOG_WARNING, "Further flags set but no bytes left\n");
          }
          if (flags & 0x01) { /* PES extension */
              pes_ext = avio_r8(s->pb);
              header_len--;
              /* Skip PES private data, program packet sequence counter
               * and P-STD buffer */
              skip  = (pes_ext >> 4) & 0xb;
              skip += skip & 0x9;
              if (pes_ext & 0x40 || skip > header_len) {
                  av_log(s, AV_LOG_WARNING, "pes_ext %X is invalid\n", pes_ext);
                  pes_ext = skip = 0;
              }
              avio_skip(s->pb, skip);
              header_len -= skip;
  
              if (pes_ext & 0x01) { /* PES extension 2 */
                  ext2_len = avio_r8(s->pb);
                  header_len--;
                  if ((ext2_len & 0x7f) > 0) {
                      id_ext = avio_r8(s->pb);
                      if ((id_ext & 0x80) == 0)
                          startcode = ((startcode & 0xff) << 8) | id_ext;
                      header_len--;
                  }
              }
          }
          if (header_len < 0)
              goto error_redo;
          avio_skip(s->pb, header_len);
      } else if (c != 0xf)
          goto redo;
      }
  
      if (startcode == PRIVATE_STREAM_1) {
          int ret = ffio_ensure_seekback(s->pb, 2);
  
          if (ret < 0)
              return ret;
  
          startcode = avio_r8(s->pb);
          m->raw_ac3 = 0;
          if (startcode == 0x0b) {
              if (avio_r8(s->pb) == 0x77) {
                  startcode = 0x80;
                  m->raw_ac3 = 1;
                  avio_skip(s->pb, -2);
              } else {
                  avio_skip(s->pb, -1);
              }
          } else {
              len--;
          }
      }
      if (len < 0)
          goto error_redo;
      if (dts != AV_NOPTS_VALUE && ppos) {
          int i;
          for (i = 0; i < s->nb_streams; i++) {
              if (startcode == s->streams[i]->id &&
                  (s->pb->seekable & AVIO_SEEKABLE_NORMAL) /* index useless on streams anyway */) {
                  ff_reduce_index(s, i);
                  av_add_index_entry(s->streams[i], *ppos, dts, 0, 0,
                                     AVINDEX_KEYFRAME /* FIXME keyframe? */);
              }
          }
      }
  
      *pstart_code = startcode;
      *ppts        = pts;
      *pdts        = dts;
      return len;
  }
  
  static int mpegps_read_packet(AVFormatContext *s,
                                AVPacket *pkt)
  {
      MpegDemuxContext *m = s->priv_data;
      AVStream *st;
      int len, startcode, i, es_type, ret;
      int pcm_dvd = 0;
      int request_probe= 0;
      enum AVCodecID codec_id = AV_CODEC_ID_NONE;
      enum AVMediaType type;
      int64_t pts, dts, dummy_pos; // dummy_pos is needed for the index building to work
  
  redo:
      len = mpegps_read_pes_header(s, &dummy_pos, &startcode, &pts, &dts);
      if (len < 0)
          return len;
  
      if (startcode >= 0x80 && startcode <= 0xcf) {
          if (len < 4)
              goto skip;
  
          if (!m->raw_ac3) {
              /* audio: skip header */
              avio_skip(s->pb, 3);
              len -= 3;
              if (startcode >= 0xb0 && startcode <= 0xbf) {
                  /* MLP/TrueHD audio has a 4-byte header */
                  avio_r8(s->pb);
                  len--;
              } else if (startcode >= 0xa0 && startcode <= 0xaf) {
                  ret = ffio_ensure_seekback(s->pb, 3);
                  if (ret < 0)
                      return ret;
                  pcm_dvd = (avio_rb24(s->pb) & 0xFF) == 0x80;
                  avio_skip(s->pb, -3);
              }
          }
      }
  
      /* now find stream */
      for (i = 0; i < s->nb_streams; i++) {
          st = s->streams[i];
          if (st->id == startcode)
              goto found;
      }
  
      es_type = m->psm_es_type[startcode & 0xff];
      if (es_type == STREAM_TYPE_VIDEO_MPEG1) {
          codec_id = AV_CODEC_ID_MPEG2VIDEO;
          type     = AVMEDIA_TYPE_VIDEO;
      } else if (es_type == STREAM_TYPE_VIDEO_MPEG2) {
          codec_id = AV_CODEC_ID_MPEG2VIDEO;
          type     = AVMEDIA_TYPE_VIDEO;
      } else if (es_type == STREAM_TYPE_AUDIO_MPEG1 ||
                 es_type == STREAM_TYPE_AUDIO_MPEG2) {
          codec_id = AV_CODEC_ID_MP3;
          type     = AVMEDIA_TYPE_AUDIO;
      } else if (es_type == STREAM_TYPE_AUDIO_AAC) {
          codec_id = AV_CODEC_ID_AAC;
          type     = AVMEDIA_TYPE_AUDIO;
      } else if (es_type == STREAM_TYPE_VIDEO_MPEG4) {
          codec_id = AV_CODEC_ID_MPEG4;
          type     = AVMEDIA_TYPE_VIDEO;
      } else if (es_type == STREAM_TYPE_VIDEO_H264) {
          codec_id = AV_CODEC_ID_H264;
          type     = AVMEDIA_TYPE_VIDEO;
      } else if (es_type == STREAM_TYPE_VIDEO_HEVC) {
          codec_id = AV_CODEC_ID_HEVC;
          type     = AVMEDIA_TYPE_VIDEO;
      } else if (es_type == STREAM_TYPE_AUDIO_AC3) {
          codec_id = AV_CODEC_ID_AC3;
          type     = AVMEDIA_TYPE_AUDIO;
      } else if (m->imkh_cctv && es_type == 0x91) {
          codec_id = AV_CODEC_ID_PCM_MULAW;
          type     = AVMEDIA_TYPE_AUDIO;
      } else if (startcode >= 0x1e0 && startcode <= 0x1ef) {
          static const unsigned char avs_seqh[4] = { 0, 0, 1, 0xb0 };
          unsigned char buf[8];
  
          avio_read(s->pb, buf, 8);
          avio_seek(s->pb, -8, SEEK_CUR);
          if (!memcmp(buf, avs_seqh, 4) && (buf[6] != 0 || buf[7] != 1))
              codec_id = AV_CODEC_ID_CAVS;
          else
              request_probe= 1;
          type = AVMEDIA_TYPE_VIDEO;
      } else if (startcode == PRIVATE_STREAM_2) {
          type = AVMEDIA_TYPE_DATA;
          codec_id = AV_CODEC_ID_DVD_NAV;
      } else if (startcode >= 0x1c0 && startcode <= 0x1df) {
          type     = AVMEDIA_TYPE_AUDIO;
          if (m->sofdec > 0) {
              codec_id = AV_CODEC_ID_ADPCM_ADX;
              // Auto-detect AC-3
              request_probe = 50;
          } else if (m->imkh_cctv && startcode == 0x1c0 && len > 80) {
              codec_id = AV_CODEC_ID_PCM_ALAW;
              request_probe = 50;
          } else {
              codec_id = AV_CODEC_ID_MP2;
              if (m->imkh_cctv)
                  request_probe = 25;
          }
      } else if (startcode >= 0x80 && startcode <= 0x87) {
          type     = AVMEDIA_TYPE_AUDIO;
          codec_id = AV_CODEC_ID_AC3;
      } else if ((startcode >= 0x88 && startcode <= 0x8f) ||
                 (startcode >= 0x98 && startcode <= 0x9f)) {
          /* 0x90 - 0x97 is reserved for SDDS in DVD specs */
          type     = AVMEDIA_TYPE_AUDIO;
          codec_id = AV_CODEC_ID_DTS;
      } else if (startcode >= 0xa0 && startcode <= 0xaf) {
          type     = AVMEDIA_TYPE_AUDIO;
          if (!pcm_dvd) {
              codec_id = AV_CODEC_ID_MLP;
          } else {
              codec_id = AV_CODEC_ID_PCM_DVD;
          }
      } else if (startcode >= 0xb0 && startcode <= 0xbf) {
          type     = AVMEDIA_TYPE_AUDIO;
          codec_id = AV_CODEC_ID_TRUEHD;
      } else if (startcode >= 0xc0 && startcode <= 0xcf) {
          /* Used for both AC-3 and E-AC-3 in EVOB files */
          type     = AVMEDIA_TYPE_AUDIO;
          codec_id = AV_CODEC_ID_AC3;
      } else if (startcode >= 0x20 && startcode <= 0x3f) {
          type     = AVMEDIA_TYPE_SUBTITLE;
          codec_id = AV_CODEC_ID_DVD_SUBTITLE;
      } else if (startcode >= 0xfd55 && startcode <= 0xfd5f) {
          type     = AVMEDIA_TYPE_VIDEO;
          codec_id = AV_CODEC_ID_VC1;
      } else {
  skip:
          /* skip packet */
          avio_skip(s->pb, len);
          goto redo;
      }
      /* no stream found: add a new stream */
      st = avformat_new_stream(s, NULL);
      if (!st)
          goto skip;
      st->id                = startcode;
      st->codecpar->codec_type = type;
      st->codecpar->codec_id   = codec_id;
      if (   st->codecpar->codec_id == AV_CODEC_ID_PCM_MULAW
          || st->codecpar->codec_id == AV_CODEC_ID_PCM_ALAW) {
          st->codecpar->channels = 1;
          st->codecpar->channel_layout = AV_CH_LAYOUT_MONO;
          st->codecpar->sample_rate = 8000;
      }
      st->request_probe     = request_probe;
      st->need_parsing      = AVSTREAM_PARSE_FULL;
  
  found:
      if (st->discard >= AVDISCARD_ALL)
          goto skip;
      if (startcode >= 0xa0 && startcode <= 0xaf) {
        if (st->codecpar->codec_id == AV_CODEC_ID_MLP) {
              if (len < 6)
                  goto skip;
              avio_skip(s->pb, 6);
              len -=6;
        }
      }
      ret = av_get_packet(s->pb, pkt, len);
  
      pkt->pts          = pts;
      pkt->dts          = dts;
      pkt->pos          = dummy_pos;
      pkt->stream_index = st->index;
  
      if (s->debug & FF_FDEBUG_TS)
          av_log(s, AV_LOG_DEBUG, "%d: pts=%0.3f dts=%0.3f size=%d\n",
              pkt->stream_index, pkt->pts / 90000.0, pkt->dts / 90000.0,
              pkt->size);
  
      return (ret < 0) ? ret : 0;
  }
  
  static int64_t mpegps_read_dts(AVFormatContext *s, int stream_index,
                                 int64_t *ppos, int64_t pos_limit)
  {
      int len, startcode;
      int64_t pos, pts, dts;
  
      pos = *ppos;
      if (avio_seek(s->pb, pos, SEEK_SET) < 0)
          return AV_NOPTS_VALUE;
  
      for (;;) {
          len = mpegps_read_pes_header(s, &pos, &startcode, &pts, &dts);
          if (len < 0) {
              if (s->debug & FF_FDEBUG_TS)
                  av_log(s, AV_LOG_DEBUG, "none (ret=%d)\n", len);
              return AV_NOPTS_VALUE;
          }
          if (startcode == s->streams[stream_index]->id &&
              dts != AV_NOPTS_VALUE) {
              break;
          }
          avio_skip(s->pb, len);
      }
      if (s->debug & FF_FDEBUG_TS)
          av_log(s, AV_LOG_DEBUG, "pos=0x%"PRIx64" dts=0x%"PRIx64" %0.3f\n",
              pos, dts, dts / 90000.0);
      *ppos = pos;
      return dts;
  }
  
  AVInputFormat ff_mpegps_demuxer = {
      .name           = "mpeg",
      .long_name      = NULL_IF_CONFIG_SMALL("MPEG-PS (MPEG-2 Program Stream)"),
      .priv_data_size = sizeof(MpegDemuxContext),
      .read_probe     = mpegps_probe,
      .read_header    = mpegps_read_header,
      .read_packet    = mpegps_read_packet,
      .read_timestamp = mpegps_read_dts,
      .flags          = AVFMT_SHOW_IDS | AVFMT_TS_DISCONT,
  };
  
  #if CONFIG_VOBSUB_DEMUXER
  
  #include "subtitles.h"
  #include "libavutil/avassert.h"
  #include "libavutil/bprint.h"
  #include "libavutil/opt.h"
  
  #define REF_STRING "# VobSub index file,"
  #define MAX_LINE_SIZE 2048
  
  typedef struct VobSubDemuxContext {
      const AVClass *class;
      AVFormatContext *sub_ctx;
      FFDemuxSubtitlesQueue q[32];
      char *sub_name;
  } VobSubDemuxContext;
  
  static int vobsub_probe(const AVProbeData *p)
  {
      if (!strncmp(p->buf, REF_STRING, sizeof(REF_STRING) - 1))
          return AVPROBE_SCORE_MAX;
      return 0;
  }
  
  static int vobsub_read_close(AVFormatContext *s)
  {
      VobSubDemuxContext *vobsub = s->priv_data;
      int i;
  
      for (i = 0; i < s->nb_streams; i++)
          ff_subtitles_queue_clean(&vobsub->q[i]);
      if (vobsub->sub_ctx)
          avformat_close_input(&vobsub->sub_ctx);
      return 0;
  }
  
  static int vobsub_read_header(AVFormatContext *s)
  {
      int i, ret = 0, header_parsed = 0, langidx = 0;
      VobSubDemuxContext *vobsub = s->priv_data;
      size_t fname_len;
      AVBPrint header;
      int64_t delay = 0;
      AVStream *st = NULL;
      int stream_id = -1;
      char id[64] = {0};
      char alt[MAX_LINE_SIZE] = {0};
      ff_const59 AVInputFormat *iformat;
  
      if (!vobsub->sub_name) {
          char *ext;
          vobsub->sub_name = av_strdup(s->url);
          if (!vobsub->sub_name) {
              return AVERROR(ENOMEM);
          }
  
          fname_len = strlen(vobsub->sub_name);
          ext = vobsub->sub_name - 3 + fname_len;
          if (fname_len < 4 || *(ext - 1) != '.') {
              av_log(s, AV_LOG_ERROR, "The input index filename is too short "
                     "to guess the associated .SUB file\n");
              return AVERROR_INVALIDDATA;
          }
          memcpy(ext, !strncmp(ext, "IDX", 3) ? "SUB" : "sub", 3);
          av_log(s, AV_LOG_VERBOSE, "IDX/SUB: %s -> %s\n", s->url, vobsub->sub_name);
      }
  
      if (!(iformat = av_find_input_format("mpeg"))) {
          return AVERROR_DEMUXER_NOT_FOUND;
      }
  
      vobsub->sub_ctx = avformat_alloc_context();
      if (!vobsub->sub_ctx) {
          return AVERROR(ENOMEM);
      }
  
      av_bprint_init(&header, 0, INT_MAX - AV_INPUT_BUFFER_PADDING_SIZE);
  
      if ((ret = ff_copy_whiteblacklists(vobsub->sub_ctx, s)) < 0)
          goto end;
  
      ret = avformat_open_input(&vobsub->sub_ctx, vobsub->sub_name, iformat, NULL);
      if (ret < 0) {
          av_log(s, AV_LOG_ERROR, "Unable to open %s as MPEG subtitles\n", vobsub->sub_name);
          goto end;
      }
  
      while (!avio_feof(s->pb)) {
          char line[MAX_LINE_SIZE];
          int len = ff_get_line(s->pb, line, sizeof(line));
  
          if (!len)
              break;
  
          line[strcspn(line, "\r\n")] = 0;
  
          if (!strncmp(line, "id:", 3)) {
              if (sscanf(line, "id: %63[^,], index: %u", id, &stream_id) != 2) {
                  av_log(s, AV_LOG_WARNING, "Unable to parse index line '%s', "
                         "assuming 'id: und, index: 0'\n", line);
                  strcpy(id, "und");
                  stream_id = 0;
              }
  
              if (stream_id >= FF_ARRAY_ELEMS(vobsub->q)) {
                  av_log(s, AV_LOG_ERROR, "Maximum number of subtitles streams reached\n");
                  ret = AVERROR(EINVAL);
                  goto end;
              }
  
              header_parsed = 1;
              alt[0] = '\0';
              /* We do not create the stream immediately to avoid adding empty
               * streams. See the following timestamp entry. */
  
              av_log(s, AV_LOG_DEBUG, "IDX stream[%d] id=%s\n", stream_id, id);
  
          } else if (!strncmp(line, "timestamp:", 10)) {
              AVPacket *sub;
              int hh, mm, ss, ms;
              int64_t pos, timestamp;
              const char *p = line + 10;
  
              if (stream_id == -1) {
                  av_log(s, AV_LOG_ERROR, "Timestamp declared before any stream\n");
                  ret = AVERROR_INVALIDDATA;
                  goto end;
              }
  
              if (!st || st->id != stream_id) {
                  st = avformat_new_stream(s, NULL);
                  if (!st) {
                      ret = AVERROR(ENOMEM);
                      goto end;
                  }
                  st->id = stream_id;
                  st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
                  st->codecpar->codec_id   = AV_CODEC_ID_DVD_SUBTITLE;
                  avpriv_set_pts_info(st, 64, 1, 1000);
                  av_dict_set(&st->metadata, "language", id, 0);
                  if (alt[0])
                      av_dict_set(&st->metadata, "title", alt, 0);
              }
  
              if (sscanf(p, "%02d:%02d:%02d:%03d, filepos: %"SCNx64,
                         &hh, &mm, &ss, &ms, &pos) != 5) {
                  av_log(s, AV_LOG_ERROR, "Unable to parse timestamp line '%s', "
                         "abort parsing\n", line);
                  ret = AVERROR_INVALIDDATA;
                  goto end;
              }
              timestamp = (hh*3600LL + mm*60LL + ss) * 1000LL + ms + delay;
              timestamp = av_rescale_q(timestamp, av_make_q(1, 1000), st->time_base);
  
              sub = ff_subtitles_queue_insert(&vobsub->q[s->nb_streams - 1], "", 0, 0);
              if (!sub) {
                  ret = AVERROR(ENOMEM);
                  goto end;
              }
              sub->pos = pos;
              sub->pts = timestamp;
              sub->stream_index = s->nb_streams - 1;
  
          } else if (!strncmp(line, "alt:", 4)) {
              const char *p = line + 4;
  
              while (*p == ' ')
                  p++;
              av_log(s, AV_LOG_DEBUG, "IDX stream[%d] name=%s\n", stream_id, p);
              av_strlcpy(alt, p, sizeof(alt));
              header_parsed = 1;
  
          } else if (!strncmp(line, "delay:", 6)) {
              int sign = 1, hh = 0, mm = 0, ss = 0, ms = 0;
              const char *p = line + 6;
  
              while (*p == ' ')
                  p++;
              if (*p == '-' || *p == '+') {
                  sign = *p == '-' ? -1 : 1;
                  p++;
              }
              sscanf(p, "%d:%d:%d:%d", &hh, &mm, &ss, &ms);
              delay = ((hh*3600LL + mm*60LL + ss) * 1000LL + ms) * sign;
  
          } else if (!strncmp(line, "langidx:", 8)) {
              const char *p = line + 8;
  
              if (sscanf(p, "%d", &langidx) != 1)
                  av_log(s, AV_LOG_ERROR, "Invalid langidx specified\n");
  
          } else if (!header_parsed) {
              if (line[0] && line[0] != '#')
                  av_bprintf(&header, "%s\n", line);
          }
      }
  
      if (langidx < s->nb_streams)
          s->streams[langidx]->disposition |= AV_DISPOSITION_DEFAULT;
  
      for (i = 0; i < s->nb_streams; i++) {
          vobsub->q[i].sort = SUB_SORT_POS_TS;
          vobsub->q[i].keep_duplicates = 1;
          ff_subtitles_queue_finalize(s, &vobsub->q[i]);
      }
  
      if (!av_bprint_is_complete(&header)) {
          ret = AVERROR(ENOMEM);
          goto end;
      }
      for (i = 0; i < s->nb_streams; i++) {
          AVCodecParameters *par = s->streams[i]->codecpar;
          ret = ff_alloc_extradata(par, header.len);
          if (ret < 0) {
              goto end;
          }
          memcpy(par->extradata, header.str, header.len);
      }
  end:
      if (ret < 0)
          vobsub_read_close(s);
      av_bprint_finalize(&header, NULL);
      return ret;
  }
  
  static int vobsub_read_packet(AVFormatContext *s, AVPacket *pkt)
  {
      VobSubDemuxContext *vobsub = s->priv_data;
      FFDemuxSubtitlesQueue *q;
      AVIOContext *pb = vobsub->sub_ctx->pb;
      int ret, psize, total_read = 0, i;
  
      int64_t min_ts = INT64_MAX;
      int sid = 0;
      for (i = 0; i < s->nb_streams; i++) {
          FFDemuxSubtitlesQueue *tmpq = &vobsub->q[i];
          int64_t ts;
          av_assert0(tmpq->nb_subs);
  
          if (tmpq->current_sub_idx >= tmpq->nb_subs)
              continue;
  
          ts = tmpq->subs[tmpq->current_sub_idx].pts;
          if (ts < min_ts) {
              min_ts = ts;
              sid = i;
          }
      }
      q = &vobsub->q[sid];
      /* The returned packet will have size zero,
       * so that it can be directly used with av_grow_packet. */
      ret = ff_subtitles_queue_read_packet(q, pkt);
      if (ret < 0)
          return ret;
  
      /* compute maximum packet size using the next packet position. This is
       * useful when the len in the header is non-sense */
      if (q->current_sub_idx < q->nb_subs) {
          psize = q->subs[q->current_sub_idx].pos - pkt->pos;
      } else {
          int64_t fsize = avio_size(pb);
          psize = fsize < 0 ? 0xffff : fsize - pkt->pos;
      }
  
      avio_seek(pb, pkt->pos, SEEK_SET);
  
      do {
          int n, to_read, startcode;
          int64_t pts, dts;
          int64_t old_pos = avio_tell(pb), new_pos;
          int pkt_size;
  
          ret = mpegps_read_pes_header(vobsub->sub_ctx, NULL, &startcode, &pts, &dts);
          if (ret < 0) {
              if (pkt->size) // raise packet even if incomplete
                  break;
              return ret;
          }
          to_read = ret & 0xffff;
          new_pos = avio_tell(pb);
          pkt_size = ret + (new_pos - old_pos);
  
          /* this prevents reads above the current packet */
          if (total_read + pkt_size > psize)
              break;
          total_read += pkt_size;
  
          /* the current chunk doesn't match the stream index (unlikely) */
          if ((startcode & 0x1f) != s->streams[pkt->stream_index]->id)
              break;
  
          ret = av_grow_packet(pkt, to_read);
          if (ret < 0)
              return ret;
  
          n = avio_read(pb, pkt->data + (pkt->size - to_read), to_read);
          if (n < to_read)
              pkt->size -= to_read - n;
      } while (total_read < psize);
  
      return 0;
  }
  
  static int vobsub_read_seek(AVFormatContext *s, int stream_index,
                              int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
  {
      VobSubDemuxContext *vobsub = s->priv_data;
  
      /* Rescale requested timestamps based on the first stream (timebase is the
       * same for all subtitles stream within a .idx/.sub). Rescaling is done just
       * like in avformat_seek_file(). */
      if (stream_index == -1 && s->nb_streams != 1) {
          int i, ret = 0;
          AVRational time_base = s->streams[0]->time_base;
          ts = av_rescale_q(ts, AV_TIME_BASE_Q, time_base);
          min_ts = av_rescale_rnd(min_ts, time_base.den,
                                  time_base.num * (int64_t)AV_TIME_BASE,
                                  AV_ROUND_UP   | AV_ROUND_PASS_MINMAX);
          max_ts = av_rescale_rnd(max_ts, time_base.den,
                                  time_base.num * (int64_t)AV_TIME_BASE,
                                  AV_ROUND_DOWN | AV_ROUND_PASS_MINMAX);
          for (i = 0; i < s->nb_streams; i++) {
              int r = ff_subtitles_queue_seek(&vobsub->q[i], s, stream_index,
                                              min_ts, ts, max_ts, flags);
              if (r < 0)
                  ret = r;
          }
          return ret;
      }
  
      if (stream_index == -1) // only 1 stream
          stream_index = 0;
      return ff_subtitles_queue_seek(&vobsub->q[stream_index], s, stream_index,
                                     min_ts, ts, max_ts, flags);
  }
  
  static const AVOption options[] = {
      { "sub_name", "URI for .sub file", offsetof(VobSubDemuxContext, sub_name), AV_OPT_TYPE_STRING, { .str = NULL }, 0, 0, AV_OPT_FLAG_DECODING_PARAM },
      { NULL }
  };
  
  static const AVClass vobsub_demuxer_class = {
      .class_name = "vobsub",
      .item_name  = av_default_item_name,
      .option     = options,
      .version    = LIBAVUTIL_VERSION_INT,
  };
  
  AVInputFormat ff_vobsub_demuxer = {
      .name           = "vobsub",
      .long_name      = NULL_IF_CONFIG_SMALL("VobSub subtitle format"),
      .priv_data_size = sizeof(VobSubDemuxContext),
      .read_probe     = vobsub_probe,
      .read_header    = vobsub_read_header,
      .read_packet    = vobsub_read_packet,
      .read_seek2     = vobsub_read_seek,
      .read_close     = vobsub_read_close,
      .flags          = AVFMT_SHOW_IDS,
      .extensions     = "idx",
      .priv_class     = &vobsub_demuxer_class,
  };
  #endif
  