text: /*
   * GXF demuxer.
   * Copyright (c) 2006 Reimar Doeffinger
   *
   * 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/channel_layout.h"
  #include "libavutil/common.h"
  #include "avformat.h"
  #include "internal.h"
  #include "gxf.h"
  #include "libavcodec/mpeg12data.h"
  
  struct gxf_stream_info {
      int64_t first_field;
      int64_t last_field;
      AVRational frames_per_second;
      int32_t fields_per_frame;
      int64_t track_aux_data;
  };
  
  /**
   * @brief parse gxf timecode and add it to metadata
   */
  static int add_timecode_metadata(AVDictionary **pm, const char *key, uint32_t timecode, int fields_per_frame)
  {
     char tmp[128];
     int field  = timecode & 0xff;
     int frame  = fields_per_frame ? field / fields_per_frame : field;
     int second = (timecode >>  8) & 0xff;
     int minute = (timecode >> 16) & 0xff;
     int hour   = (timecode >> 24) & 0x1f;
     int drop   = (timecode >> 29) & 1;
     // bit 30: color_frame, unused
     // ignore invalid time code
     if (timecode >> 31)
         return 0;
     snprintf(tmp, sizeof(tmp), "%02d:%02d:%02d%c%02d",
         hour, minute, second, drop ? ';' : ':', frame);
     return av_dict_set(pm, key, tmp, 0);
  }
  
  /**
   * @brief parses a packet header, extracting type and length
   * @param pb AVIOContext to read header from
   * @param type detected packet type is stored here
   * @param length detected packet length, excluding header is stored here
   * @return 0 if header not found or contains invalid data, 1 otherwise
   */
  static int parse_packet_header(AVIOContext *pb, GXFPktType *type, int *length) {
      if (avio_rb32(pb))
          return 0;
      if (avio_r8(pb) != 1)
          return 0;
      *type = avio_r8(pb);
      *length = avio_rb32(pb);
      if ((*length >> 24) || *length < 16)
          return 0;
      *length -= 16;
      if (avio_rb32(pb))
          return 0;
      if (avio_r8(pb) != 0xe1)
          return 0;
      if (avio_r8(pb) != 0xe2)
          return 0;
      return 1;
  }
  
  /**
   * @brief check if file starts with a PKT_MAP header
   */
  static int gxf_probe(const AVProbeData *p) {
      static const uint8_t startcode[] = {0, 0, 0, 0, 1, 0xbc}; // start with map packet
      static const uint8_t endcode[] = {0, 0, 0, 0, 0xe1, 0xe2};
      if (!memcmp(p->buf, startcode, sizeof(startcode)) &&
          !memcmp(&p->buf[16 - sizeof(endcode)], endcode, sizeof(endcode)))
          return AVPROBE_SCORE_MAX;
      return 0;
  }
  
  /**
   * @brief gets the stream index for the track with the specified id, creates new
   *        stream if not found
   * @param id     id of stream to find / add
   * @param format stream format identifier
   */
  static int get_sindex(AVFormatContext *s, int id, int format) {
      int i;
      AVStream *st = NULL;
      i = ff_find_stream_index(s, id);
      if (i >= 0)
          return i;
      st = avformat_new_stream(s, NULL);
      if (!st)
          return AVERROR(ENOMEM);
      st->id = id;
      switch (format) {
          case 3:
          case 4:
              st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
              st->codecpar->codec_id = AV_CODEC_ID_MJPEG;
              break;
          case 13:
          case 14:
          case 15:
          case 16:
          case 25:
              st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
              st->codecpar->codec_id = AV_CODEC_ID_DVVIDEO;
              break;
          case 11:
          case 12:
          case 20:
              st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
              st->codecpar->codec_id = AV_CODEC_ID_MPEG2VIDEO;
              st->need_parsing = AVSTREAM_PARSE_HEADERS; //get keyframe flag etc.
              break;
          case 22:
          case 23:
              st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
              st->codecpar->codec_id = AV_CODEC_ID_MPEG1VIDEO;
              st->need_parsing = AVSTREAM_PARSE_HEADERS; //get keyframe flag etc.
              break;
          case 9:
              st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
              st->codecpar->codec_id = AV_CODEC_ID_PCM_S24LE;
              st->codecpar->channels = 1;
              st->codecpar->channel_layout = AV_CH_LAYOUT_MONO;
              st->codecpar->sample_rate = 48000;
              st->codecpar->bit_rate = 3 * 1 * 48000 * 8;
              st->codecpar->block_align = 3 * 1;
              st->codecpar->bits_per_coded_sample = 24;
              break;
          case 10:
              st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
              st->codecpar->codec_id = AV_CODEC_ID_PCM_S16LE;
              st->codecpar->channels = 1;
              st->codecpar->channel_layout = AV_CH_LAYOUT_MONO;
              st->codecpar->sample_rate = 48000;
              st->codecpar->bit_rate = 2 * 1 * 48000 * 8;
              st->codecpar->block_align = 2 * 1;
              st->codecpar->bits_per_coded_sample = 16;
              break;
          case 17:
              st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
              st->codecpar->codec_id = AV_CODEC_ID_AC3;
              st->codecpar->channels = 2;
              st->codecpar->channel_layout = AV_CH_LAYOUT_STEREO;
              st->codecpar->sample_rate = 48000;
              break;
          case 26: /* AVCi50 / AVCi100 (AVC Intra) */
          case 29: /* AVCHD */
              st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
              st->codecpar->codec_id = AV_CODEC_ID_H264;
              st->need_parsing = AVSTREAM_PARSE_HEADERS;
              break;
          // timecode tracks:
          case 7:
          case 8:
          case 24:
              st->codecpar->codec_type = AVMEDIA_TYPE_DATA;
              st->codecpar->codec_id = AV_CODEC_ID_NONE;
              break;
          case 30:
              st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
              st->codecpar->codec_id = AV_CODEC_ID_DNXHD;
              break;
          default:
              st->codecpar->codec_type = AVMEDIA_TYPE_UNKNOWN;
              st->codecpar->codec_id = AV_CODEC_ID_NONE;
              break;
      }
      return s->nb_streams - 1;
  }
  
  /**
   * @brief filters out interesting tags from material information.
   * @param len length of tag section, will be adjusted to contain remaining bytes
   * @param si struct to store collected information into
   */
  static void gxf_material_tags(AVIOContext *pb, int *len, struct gxf_stream_info *si) {
      si->first_field = AV_NOPTS_VALUE;
      si->last_field = AV_NOPTS_VALUE;
      while (*len >= 2) {
          GXFMatTag tag = avio_r8(pb);
          int tlen = avio_r8(pb);
          *len -= 2;
          if (tlen > *len)
              return;
          *len -= tlen;
          if (tlen == 4) {
              uint32_t value = avio_rb32(pb);
              if (tag == MAT_FIRST_FIELD)
                  si->first_field = value;
              else if (tag == MAT_LAST_FIELD)
                  si->last_field = value;
          } else
              avio_skip(pb, tlen);
      }
  }
  
  static const AVRational frame_rate_tab[] = {
      {   60,    1},
      {60000, 1001},
      {   50,    1},
      {   30,    1},
      {30000, 1001},
      {   25,    1},
      {   24,    1},
      {24000, 1001},
      {    0,    0},
  };
  
  /**
   * @brief convert fps tag value to AVRational fps
   * @param fps fps value from tag
   * @return fps as AVRational, or 0 / 0 if unknown
   */
  static AVRational fps_tag2avr(int32_t fps) {
      if (fps < 1 || fps > 9) fps = 9;
      return frame_rate_tab[fps - 1];
  }
  
  /**
   * @brief convert UMF attributes flags to AVRational fps
   * @param flags UMF flags to convert
   * @return fps as AVRational, or 0 / 0 if unknown
   */
  static AVRational fps_umf2avr(uint32_t flags) {
      static const AVRational map[] = {{50, 1}, {60000, 1001}, {24, 1},
          {25, 1}, {30000, 1001}};
      int idx =  av_log2((flags & 0x7c0) >> 6);
      return map[idx];
  }
  
  /**
   * @brief filters out interesting tags from track information.
   * @param len length of tag section, will be adjusted to contain remaining bytes
   * @param si struct to store collected information into
   */
  static void gxf_track_tags(AVIOContext *pb, int *len, struct gxf_stream_info *si) {
      si->frames_per_second = (AVRational){0, 0};
      si->fields_per_frame = 0;
      si->track_aux_data = 0x80000000;
      while (*len >= 2) {
          GXFTrackTag tag = avio_r8(pb);
          int tlen = avio_r8(pb);
          *len -= 2;
          if (tlen > *len)
              return;
          *len -= tlen;
          if (tlen == 4) {
              uint32_t value = avio_rb32(pb);
              if (tag == TRACK_FPS)
                  si->frames_per_second = fps_tag2avr(value);
              else if (tag == TRACK_FPF && (value == 1 || value == 2))
                  si->fields_per_frame = value;
          } else if (tlen == 8 && tag == TRACK_AUX)
              si->track_aux_data = avio_rl64(pb);
          else
              avio_skip(pb, tlen);
      }
  }
  
  /**
   * @brief read index from FLT packet into stream 0 av_index
   */
  static void gxf_read_index(AVFormatContext *s, int pkt_len) {
      AVIOContext *pb = s->pb;
      AVStream *st;
      uint32_t fields_per_map, map_cnt;
      int i;
      if (pkt_len < 8)
          return;
      fields_per_map = avio_rl32(pb);
      map_cnt = avio_rl32(pb);
      pkt_len -= 8;
      if ((s->flags & AVFMT_FLAG_IGNIDX) || !s->streams) {
          avio_skip(pb, pkt_len);
          return;
      }
      st = s->streams[0];
      if (map_cnt > 1000) {
          av_log(s, AV_LOG_ERROR,
                 "too many index entries %"PRIu32" (%"PRIx32")\n",
                 map_cnt, map_cnt);
          map_cnt = 1000;
      }
      if (pkt_len < 4 * map_cnt) {
          av_log(s, AV_LOG_ERROR, "invalid index length\n");
          avio_skip(pb, pkt_len);
          return;
      }
      pkt_len -= 4 * map_cnt;
      av_add_index_entry(st, 0, 0, 0, 0, 0);
      for (i = 0; i < map_cnt; i++)
          av_add_index_entry(st, (uint64_t)avio_rl32(pb) * 1024,
                             i * (uint64_t)fields_per_map + 1, 0, 0, 0);
      avio_skip(pb, pkt_len);
  }
  
  static int gxf_header(AVFormatContext *s) {
      AVIOContext *pb = s->pb;
      GXFPktType pkt_type;
      int map_len;
      int len;
      AVRational main_timebase = {0, 0};
      struct gxf_stream_info *si = s->priv_data;
      int i;
      if (!parse_packet_header(pb, &pkt_type, &map_len) || pkt_type != PKT_MAP) {
          av_log(s, AV_LOG_ERROR, "map packet not found\n");
          return 0;
      }
      map_len -= 2;
      if (avio_r8(pb) != 0x0e0 || avio_r8(pb) != 0xff) {
          av_log(s, AV_LOG_ERROR, "unknown version or invalid map preamble\n");
          return 0;
      }
      map_len -= 2;
      len = avio_rb16(pb); // length of material data section
      if (len > map_len) {
          av_log(s, AV_LOG_ERROR, "material data longer than map data\n");
          return 0;
      }
      map_len -= len;
      gxf_material_tags(pb, &len, si);
      avio_skip(pb, len);
      map_len -= 2;
      len = avio_rb16(pb); // length of track description
      if (len > map_len) {
          av_log(s, AV_LOG_ERROR, "track description longer than map data\n");
          return 0;
      }
      map_len -= len;
      while (len > 0) {
          int track_type, track_id, track_len;
          AVStream *st;
          int idx;
          len -= 4;
          track_type = avio_r8(pb);
          track_id = avio_r8(pb);
          track_len = avio_rb16(pb);
          len -= track_len;
          if (!(track_type & 0x80)) {
             av_log(s, AV_LOG_ERROR, "invalid track type %x\n", track_type);
             continue;
          }
          track_type &= 0x7f;
          if ((track_id & 0xc0) != 0xc0) {
             av_log(s, AV_LOG_ERROR, "invalid track id %x\n", track_id);
             continue;
          }
          track_id &= 0x3f;
          gxf_track_tags(pb, &track_len, si);
          // check for timecode tracks
          if (track_type == 7 || track_type == 8 || track_type == 24) {
              add_timecode_metadata(&s->metadata, "timecode",
                                    si->track_aux_data & 0xffffffff,
                                    si->fields_per_frame);
  
          }
          avio_skip(pb, track_len);
  
          idx = get_sindex(s, track_id, track_type);
          if (idx < 0) continue;
          st = s->streams[idx];
          if (!main_timebase.num || !main_timebase.den) {
              main_timebase.num = si->frames_per_second.den;
              main_timebase.den = si->frames_per_second.num * 2;
          }
          st->start_time = si->first_field;
          if (si->first_field != AV_NOPTS_VALUE && si->last_field != AV_NOPTS_VALUE)
              st->duration = si->last_field - si->first_field;
      }
      if (len < 0)
          av_log(s, AV_LOG_ERROR, "invalid track description length specified\n");
      if (map_len)
          avio_skip(pb, map_len);
      if (!parse_packet_header(pb, &pkt_type, &len)) {
          av_log(s, AV_LOG_ERROR, "sync lost in header\n");
          return -1;
      }
      if (pkt_type == PKT_FLT) {
          gxf_read_index(s, len);
          if (!parse_packet_header(pb, &pkt_type, &len)) {
              av_log(s, AV_LOG_ERROR, "sync lost in header\n");
              return -1;
          }
      }
      if (pkt_type == PKT_UMF) {
          if (len >= 0x39) {
              AVRational fps;
              len -= 0x39;
              avio_skip(pb, 5); // preamble
              avio_skip(pb, 0x30); // payload description
              fps = fps_umf2avr(avio_rl32(pb));
              if (!main_timebase.num || !main_timebase.den) {
                  av_log(s, AV_LOG_WARNING, "No FPS track tag, using UMF fps tag."
                                            " This might give wrong results.\n");
                  // this may not always be correct, but simply the best we can get
                  main_timebase.num = fps.den;
                  main_timebase.den = fps.num * 2;
              }
  
              if (len >= 0x18) {
                  len -= 0x18;
                  avio_skip(pb, 0x10);
                  add_timecode_metadata(&s->metadata, "timecode_at_mark_in",
                                        avio_rl32(pb), si->fields_per_frame);
                  add_timecode_metadata(&s->metadata, "timecode_at_mark_out",
                                        avio_rl32(pb), si->fields_per_frame);
              }
          } else
              av_log(s, AV_LOG_INFO, "UMF packet too short\n");
      } else
          av_log(s, AV_LOG_INFO, "UMF packet missing\n");
      avio_skip(pb, len);
      // set a fallback value, 60000/1001 is specified for audio-only files
      // so use that regardless of why we do not know the video frame rate.
      if (!main_timebase.num || !main_timebase.den)
          main_timebase = (AVRational){1001, 60000};
      for (i = 0; i < s->nb_streams; i++) {
          AVStream *st = s->streams[i];
          avpriv_set_pts_info(st, 32, main_timebase.num, main_timebase.den);
      }
      return 0;
  }
  
  #define READ_ONE() \
      { \
          if (!max_interval-- || avio_feof(pb)) \
              goto out; \
          tmp = tmp << 8 | avio_r8(pb); \
      }
  
  /**
   * @brief resync the stream on the next media packet with specified properties
   * @param max_interval how many bytes to search for matching packet at most
   * @param track track id the media packet must belong to, -1 for any
   * @param timestamp minimum timestamp (== field number) the packet must have, -1 for any
   * @return timestamp of packet found
   */
  static int64_t gxf_resync_media(AVFormatContext *s, uint64_t max_interval, int track, int timestamp) {
      uint32_t tmp;
      uint64_t last_pos;
      uint64_t last_found_pos = 0;
      int cur_track;
      int64_t cur_timestamp = AV_NOPTS_VALUE;
      int len;
      AVIOContext *pb = s->pb;
      GXFPktType type;
      tmp = avio_rb32(pb);
  start:
      while (tmp)
          READ_ONE();
      READ_ONE();
      if (tmp != 1)
          goto start;
      last_pos = avio_tell(pb);
      if (avio_seek(pb, -5, SEEK_CUR) < 0)
          goto out;
      if (!parse_packet_header(pb, &type, &len) || type != PKT_MEDIA) {
          if (avio_seek(pb, last_pos, SEEK_SET) < 0)
              goto out;
          goto start;
      }
      avio_r8(pb);
      cur_track = avio_r8(pb);
      cur_timestamp = avio_rb32(pb);
      last_found_pos = avio_tell(pb) - 16 - 6;
      if ((track >= 0 && track != cur_track) || (timestamp >= 0 && timestamp > cur_timestamp)) {
          if (avio_seek(pb, last_pos, SEEK_SET) >= 0)
              goto start;
      }
  out:
      if (last_found_pos)
          avio_seek(pb, last_found_pos, SEEK_SET);
      return cur_timestamp;
  }
  
  static int gxf_packet(AVFormatContext *s, AVPacket *pkt) {
      AVIOContext *pb = s->pb;
      GXFPktType pkt_type;
      int pkt_len;
      struct gxf_stream_info *si = s->priv_data;
  
      while (!pb->eof_reached) {
          AVStream *st;
          int track_type, track_id, ret;
          int field_nr, field_info, skip = 0;
          int stream_index;
          if (!parse_packet_header(pb, &pkt_type, &pkt_len)) {
              if (!avio_feof(pb))
                  av_log(s, AV_LOG_ERROR, "sync lost\n");
              return -1;
          }
          if (pkt_type == PKT_FLT) {
              gxf_read_index(s, pkt_len);
              continue;
          }
          if (pkt_type != PKT_MEDIA) {
              avio_skip(pb, pkt_len);
              continue;
          }
          if (pkt_len < 16) {
              av_log(s, AV_LOG_ERROR, "invalid media packet length\n");
              continue;
          }
          pkt_len -= 16;
          track_type = avio_r8(pb);
          track_id = avio_r8(pb);
          stream_index = get_sindex(s, track_id, track_type);
          if (stream_index < 0)
              return stream_index;
          st = s->streams[stream_index];
          field_nr = avio_rb32(pb);
          field_info = avio_rb32(pb);
          avio_rb32(pb); // "timeline" field number
          avio_r8(pb); // flags
          avio_r8(pb); // reserved
          if (st->codecpar->codec_id == AV_CODEC_ID_PCM_S24LE ||
              st->codecpar->codec_id == AV_CODEC_ID_PCM_S16LE) {
              int first = field_info >> 16;
              int last  = field_info & 0xffff; // last is exclusive
              int bps = av_get_bits_per_sample(st->codecpar->codec_id)>>3;
              if (first <= last && last*bps <= pkt_len) {
                  avio_skip(pb, first*bps);
                  skip = pkt_len - last*bps;
                  pkt_len = (last-first)*bps;
              } else
                  av_log(s, AV_LOG_ERROR, "invalid first and last sample values\n");
          }
          ret = av_get_packet(pb, pkt, pkt_len);
          if (skip)
              avio_skip(pb, skip);
          pkt->stream_index = stream_index;
          pkt->dts = field_nr;
  
          //set duration manually for DV or else lavf misdetects the frame rate
          if (st->codecpar->codec_id == AV_CODEC_ID_DVVIDEO)
              pkt->duration = si->fields_per_frame;
  
          return ret;
      }
      return AVERROR_EOF;
  }
  
  static int gxf_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags) {
      int64_t res = 0;
      uint64_t pos;
      uint64_t maxlen = 100 * 1024 * 1024;
      AVStream *st = s->streams[0];
      int64_t start_time = s->streams[stream_index]->start_time;
      int64_t found;
      int idx;
      if (timestamp < start_time) timestamp = start_time;
      idx = av_index_search_timestamp(st, timestamp - start_time,
                                      AVSEEK_FLAG_ANY | AVSEEK_FLAG_BACKWARD);
      if (idx < 0)
          return -1;
      pos = st->internal->index_entries[idx].pos;
      if (idx < st->internal->nb_index_entries - 2)
          maxlen = st->internal->index_entries[idx + 2].pos - pos;
      maxlen = FFMAX(maxlen, 200 * 1024);
      res = avio_seek(s->pb, pos, SEEK_SET);
      if (res < 0)
          return res;
      found = gxf_resync_media(s, maxlen, -1, timestamp);
      if (FFABS(found - timestamp) > 4)
          return -1;
      return 0;
  }
  
  static int64_t gxf_read_timestamp(AVFormatContext *s, int stream_index,
                                    int64_t *pos, int64_t pos_limit) {
      AVIOContext *pb = s->pb;
      int64_t res;
      if (avio_seek(pb, *pos, SEEK_SET) < 0)
          return AV_NOPTS_VALUE;
      res = gxf_resync_media(s, pos_limit - *pos, -1, -1);
      *pos = avio_tell(pb);
      return res;
  }
  
  AVInputFormat ff_gxf_demuxer = {
      .name           = "gxf",
      .long_name      = NULL_IF_CONFIG_SMALL("GXF (General eXchange Format)"),
      .priv_data_size = sizeof(struct gxf_stream_info),
      .read_probe     = gxf_probe,
      .read_header    = gxf_header,
      .read_packet    = gxf_packet,
      .read_seek      = gxf_seek,
      .read_timestamp = gxf_read_timestamp,
  };
  