text: /*
   * MXF demuxer.
   * Copyright (c) 2006 SmartJog S.A., Baptiste Coudurier <baptiste dot coudurier at smartjog dot com>
   *
   * This file is part of Libav.
   *
   * Libav 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.
   *
   * Libav 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 Libav; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  /*
   * References
   * SMPTE 336M KLV Data Encoding Protocol Using Key-Length-Value
   * SMPTE 377M MXF File Format Specifications
   * SMPTE 378M Operational Pattern 1a
   * SMPTE 379M MXF Generic Container
   * SMPTE 381M Mapping MPEG Streams into the MXF Generic Container
   * SMPTE 382M Mapping AES3 and Broadcast Wave Audio into the MXF Generic Container
   * SMPTE 383M Mapping DV-DIF Data to the MXF Generic Container
   *
   * Principle
   * Search for Track numbers which will identify essence element KLV packets.
   * Search for SourcePackage which define tracks which contains Track numbers.
   * Material Package contains tracks with reference to SourcePackage tracks.
   * Search for Descriptors (Picture, Sound) which contains codec info and parameters.
   * Assign Descriptors to correct Tracks.
   *
   * Metadata reading functions read Local Tags, get InstanceUID(0x3C0A) then add MetaDataSet to MXFContext.
   * Metadata parsing resolves Strong References to objects.
   *
   * Simple demuxer, only OP1A supported and some files might not work at all.
   * Only tracks with associated descriptors will be decoded. "Highly Desirable" SMPTE 377M D.1
   */
  
  #include <inttypes.h>
  
  #include "libavutil/aes.h"
  #include "libavutil/mathematics.h"
  #include "libavcodec/bytestream.h"
  #include "avformat.h"
  #include "internal.h"
  #include "mxf.h"
  
  typedef enum {
      Header,
      BodyPartition,
      Footer
  } MXFPartitionType;
  
  typedef enum {
      OP1a = 1,
      OP1b,
      OP1c,
      OP2a,
      OP2b,
      OP2c,
      OP3a,
      OP3b,
      OP3c,
      OPAtom,
      OPSonyOpt,  /* FATE sample, violates the spec in places */
  } MXFOP;
  
  typedef struct MXFPartition {
      int closed;
      int complete;
      MXFPartitionType type;
      uint64_t previous_partition;
      int index_sid;
      int body_sid;
      int64_t this_partition;
      int64_t essence_offset;         ///< absolute offset of essence
      int64_t essence_length;
      int32_t kag_size;
      int64_t header_byte_count;
      int64_t index_byte_count;
      int pack_length;
  } MXFPartition;
  
  typedef struct MXFCryptoContext {
      UID uid;
      enum MXFMetadataSetType type;
      UID source_container_ul;
  } MXFCryptoContext;
  
  typedef struct MXFStructuralComponent {
      UID uid;
      enum MXFMetadataSetType type;
      UID source_package_uid;
      UID data_definition_ul;
      int64_t duration;
      int64_t start_position;
      int source_track_id;
  } MXFStructuralComponent;
  
  typedef struct MXFSequence {
      UID uid;
      enum MXFMetadataSetType type;
      UID data_definition_ul;
      UID *structural_components_refs;
      int structural_components_count;
      int64_t duration;
      uint8_t origin;
  } MXFSequence;
  
  typedef struct MXFTrack {
      UID uid;
      enum MXFMetadataSetType type;
      MXFSequence *sequence; /* mandatory, and only one */
      UID sequence_ref;
      int track_id;
      uint8_t track_number[4];
      AVRational edit_rate;
      int intra_only;
      uint64_t sample_count;
      int64_t original_duration; /* st->duration in SampleRate/EditRate units */
  } MXFTrack;
  
  typedef struct MXFDescriptor {
      UID uid;
      enum MXFMetadataSetType type;
      UID essence_container_ul;
      UID essence_codec_ul;
      AVRational sample_rate;
      AVRational aspect_ratio;
      int width;
      int height; /* Field height, not frame height */
      int frame_layout; /* See MXFFrameLayout enum */
  #define MXF_TFF 1
  #define MXF_BFF 2
      int field_dominance;
      int channels;
      int bits_per_sample;
      unsigned int component_depth;
      unsigned int horiz_subsampling;
      unsigned int vert_subsampling;
      UID *sub_descriptors_refs;
      int sub_descriptors_count;
      int linked_track_id;
      uint8_t *extradata;
      int extradata_size;
      enum AVPixelFormat pix_fmt;
  } MXFDescriptor;
  
  typedef struct MXFIndexTableSegment {
      UID uid;
      enum MXFMetadataSetType type;
      int edit_unit_byte_count;
      int index_sid;
      int body_sid;
      AVRational index_edit_rate;
      uint64_t index_start_position;
      uint64_t index_duration;
      int8_t *temporal_offset_entries;
      int *flag_entries;
      uint64_t *stream_offset_entries;
      int nb_index_entries;
  } MXFIndexTableSegment;
  
  typedef struct MXFPackage {
      UID uid;
      enum MXFMetadataSetType type;
      UID package_uid;
      UID *tracks_refs;
      int tracks_count;
      MXFDescriptor *descriptor; /* only one */
      UID descriptor_ref;
  } MXFPackage;
  
  typedef struct MXFMetadataSet {
      UID uid;
      enum MXFMetadataSetType type;
  } MXFMetadataSet;
  
  /* decoded index table */
  typedef struct MXFIndexTable {
      int index_sid;
      int body_sid;
      int nb_ptses;               /* number of PTSes or total duration of index */
      int64_t first_dts;          /* DTS = EditUnit + first_dts */
      int64_t *ptses;             /* maps EditUnit -> PTS */
      int nb_segments;
      MXFIndexTableSegment **segments;    /* sorted by IndexStartPosition */
      AVIndexEntry *fake_index;   /* used for calling ff_index_search_timestamp() */
  } MXFIndexTable;
  
  typedef struct MXFContext {
      MXFPartition *partitions;
      unsigned partitions_count;
      MXFOP op;
      UID *packages_refs;
      int packages_count;
      MXFMetadataSet **metadata_sets;
      int metadata_sets_count;
      AVFormatContext *fc;
      struct AVAES *aesc;
      uint8_t *local_tags;
      int local_tags_count;
      uint64_t last_partition;
      uint64_t footer_partition;
      KLVPacket current_klv_data;
      int current_klv_index;
      int run_in;
      MXFPartition *current_partition;
      int parsing_backward;
      int64_t last_forward_tell;
      int last_forward_partition;
      int current_edit_unit;
      int nb_index_tables;
      MXFIndexTable *index_tables;
      int edit_units_per_packet;      ///< how many edit units to read at a time (PCM, OPAtom)
  } MXFContext;
  
  enum MXFWrappingScheme {
      Frame,
      Clip,
  };
  
  /* NOTE: klv_offset is not set (-1) for local keys */
  typedef int MXFMetadataReadFunc(void *arg, AVIOContext *pb, int tag, int size, UID uid, int64_t klv_offset);
  
  typedef struct MXFMetadataReadTableEntry {
      const UID key;
      MXFMetadataReadFunc *read;
      int ctx_size;
      enum MXFMetadataSetType type;
  } MXFMetadataReadTableEntry;
  
  /* partial keys to match */
  static const uint8_t mxf_header_partition_pack_key[]       = { 0x06,0x0e,0x2b,0x34,0x02,0x05,0x01,0x01,0x0d,0x01,0x02,0x01,0x01,0x02 };
  static const uint8_t mxf_essence_element_key[]             = { 0x06,0x0e,0x2b,0x34,0x01,0x02,0x01,0x01,0x0d,0x01,0x03,0x01 };
  static const uint8_t mxf_avid_essence_element_key[]        = { 0x06,0x0e,0x2b,0x34,0x01,0x02,0x01,0x01,0x0e,0x04,0x03,0x01 };
  static const uint8_t mxf_system_item_key[]                 = { 0x06,0x0e,0x2b,0x34,0x02,0x05,0x01,0x01,0x0d,0x01,0x03,0x01,0x04 };
  static const uint8_t mxf_klv_key[]                         = { 0x06,0x0e,0x2b,0x34 };
  /* complete keys to match */
  static const uint8_t mxf_crypto_source_container_ul[]      = { 0x06,0x0e,0x2b,0x34,0x01,0x01,0x01,0x09,0x06,0x01,0x01,0x02,0x02,0x00,0x00,0x00 };
  static const uint8_t mxf_encrypted_triplet_key[]           = { 0x06,0x0e,0x2b,0x34,0x02,0x04,0x01,0x07,0x0d,0x01,0x03,0x01,0x02,0x7e,0x01,0x00 };
  static const uint8_t mxf_encrypted_essence_container[]     = { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x07,0x0d,0x01,0x03,0x01,0x02,0x0b,0x01,0x00 };
  static const uint8_t mxf_random_index_pack_key[]           = { 0x06,0x0e,0x2b,0x34,0x02,0x05,0x01,0x01,0x0d,0x01,0x02,0x01,0x01,0x11,0x01,0x00 };
  static const uint8_t mxf_sony_mpeg4_extradata[]            = { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x01,0x0e,0x06,0x06,0x02,0x02,0x01,0x00,0x00 };
  
  #define IS_KLV_KEY(x, y) (!memcmp(x, y, sizeof(y)))
  
  static int64_t klv_decode_ber_length(AVIOContext *pb)
  {
      uint64_t size = avio_r8(pb);
      if (size & 0x80) { /* long form */
          int bytes_num = size & 0x7f;
          /* SMPTE 379M 5.3.4 guarantee that bytes_num must not exceed 8 bytes */
          if (bytes_num > 8)
              return AVERROR_INVALIDDATA;
          size = 0;
          while (bytes_num--)
              size = size << 8 | avio_r8(pb);
      }
      return size;
  }
  
  static int mxf_read_sync(AVIOContext *pb, const uint8_t *key, unsigned size)
  {
      int i, b;
      for (i = 0; i < size && !pb->eof_reached; i++) {
          b = avio_r8(pb);
          if (b == key[0])
              i = 0;
          else if (b != key[i])
              i = -1;
      }
      return i == size;
  }
  
  static int klv_read_packet(KLVPacket *klv, AVIOContext *pb)
  {
      if (!mxf_read_sync(pb, mxf_klv_key, 4))
          return AVERROR_INVALIDDATA;
      klv->offset = avio_tell(pb) - 4;
      memcpy(klv->key, mxf_klv_key, 4);
      avio_read(pb, klv->key + 4, 12);
      klv->length = klv_decode_ber_length(pb);
      return klv->length == -1 ? -1 : 0;
  }
  
  static int mxf_get_stream_index(AVFormatContext *s, KLVPacket *klv)
  {
      int i;
  
      for (i = 0; i < s->nb_streams; i++) {
          MXFTrack *track = s->streams[i]->priv_data;
          /* SMPTE 379M 7.3 */
          if (!memcmp(klv->key + sizeof(mxf_essence_element_key), track->track_number, sizeof(track->track_number)))
              return i;
      }
      /* return 0 if only one stream, for OP Atom files with 0 as track number */
      return s->nb_streams == 1 ? 0 : -1;
  }
  
  /* XXX: use AVBitStreamFilter */
  static int mxf_get_d10_aes3_packet(AVIOContext *pb, AVStream *st, AVPacket *pkt, int64_t length)
  {
      const uint8_t *buf_ptr, *end_ptr;
      uint8_t *data_ptr;
      int i;
  
      if (length > 61444) /* worst case PAL 1920 samples 8 channels */
          return AVERROR_INVALIDDATA;
      length = av_get_packet(pb, pkt, length);
      if (length < 0)
          return length;
      data_ptr = pkt->data;
      end_ptr = pkt->data + length;
      buf_ptr = pkt->data + 4; /* skip SMPTE 331M header */
      for (; end_ptr - buf_ptr >= st->codecpar->channels * 4; ) {
          for (i = 0; i < st->codecpar->channels; i++) {
              uint32_t sample = bytestream_get_le32(&buf_ptr);
              if (st->codecpar->bits_per_coded_sample == 24)
                  bytestream_put_le24(&data_ptr, (sample >> 4) & 0xffffff);
              else
                  bytestream_put_le16(&data_ptr, (sample >> 12) & 0xffff);
          }
          buf_ptr += 32 - st->codecpar->channels*4; // always 8 channels stored SMPTE 331M
      }
      av_shrink_packet(pkt, data_ptr - pkt->data);
      return 0;
  }
  
  static int mxf_decrypt_triplet(AVFormatContext *s, AVPacket *pkt, KLVPacket *klv)
  {
      static const uint8_t checkv[16] = {0x43, 0x48, 0x55, 0x4b, 0x43, 0x48, 0x55, 0x4b, 0x43, 0x48, 0x55, 0x4b, 0x43, 0x48, 0x55, 0x4b};
      MXFContext *mxf = s->priv_data;
      AVIOContext *pb = s->pb;
      int64_t end = avio_tell(pb) + klv->length;
      int64_t size;
      uint64_t orig_size;
      uint64_t plaintext_size;
      uint8_t ivec[16];
      uint8_t tmpbuf[16];
      int index;
  
      if (!mxf->aesc && s->key && s->keylen == 16) {
          mxf->aesc = av_aes_alloc();
          if (!mxf->aesc)
              return AVERROR(ENOMEM);
          av_aes_init(mxf->aesc, s->key, 128, 1);
      }
      // crypto context
      avio_skip(pb, klv_decode_ber_length(pb));
      // plaintext offset
      klv_decode_ber_length(pb);
      plaintext_size = avio_rb64(pb);
      // source klv key
      klv_decode_ber_length(pb);
      avio_read(pb, klv->key, 16);
      if (!IS_KLV_KEY(klv, mxf_essence_element_key))
          return AVERROR_INVALIDDATA;
      index = mxf_get_stream_index(s, klv);
      if (index < 0)
          return AVERROR_INVALIDDATA;
      // source size
      klv_decode_ber_length(pb);
      orig_size = avio_rb64(pb);
      if (orig_size < plaintext_size)
          return AVERROR_INVALIDDATA;
      // enc. code
      size = klv_decode_ber_length(pb);
      if (size < 32 || size - 32 < orig_size)
          return AVERROR_INVALIDDATA;
      avio_read(pb, ivec, 16);
      avio_read(pb, tmpbuf, 16);
      if (mxf->aesc)
          av_aes_crypt(mxf->aesc, tmpbuf, tmpbuf, 1, ivec, 1);
      if (memcmp(tmpbuf, checkv, 16))
          av_log(s, AV_LOG_ERROR, "probably incorrect decryption key\n");
      size -= 32;
      size = av_get_packet(pb, pkt, size);
      if (size < 0)
          return size;
      else if (size < plaintext_size)
          return AVERROR_INVALIDDATA;
      size -= plaintext_size;
      if (mxf->aesc)
          av_aes_crypt(mxf->aesc, &pkt->data[plaintext_size],
                       &pkt->data[plaintext_size], size >> 4, ivec, 1);
      av_shrink_packet(pkt, orig_size);
      pkt->stream_index = index;
      avio_skip(pb, end - avio_tell(pb));
      return 0;
  }
  
  static int mxf_read_primer_pack(void *arg, AVIOContext *pb, int tag, int size, UID uid, int64_t klv_offset)
  {
      MXFContext *mxf = arg;
      int item_num = avio_rb32(pb);
      int item_len = avio_rb32(pb);
  
      if (item_len != 18) {
          avpriv_request_sample(pb, "Primer pack item length %d", item_len);
          return AVERROR_PATCHWELCOME;
      }
      if (item_num > UINT_MAX / item_len)
          return AVERROR_INVALIDDATA;
      mxf->local_tags_count = item_num;
      mxf->local_tags = av_malloc(item_num*item_len);
      if (!mxf->local_tags)
          return AVERROR(ENOMEM);
      avio_read(pb, mxf->local_tags, item_num*item_len);
      return 0;
  }
  
  static int mxf_read_partition_pack(void *arg, AVIOContext *pb, int tag, int size, UID uid, int64_t klv_offset)
  {
      MXFContext *mxf = arg;
      MXFPartition *partition;
      UID op;
      uint64_t footer_partition;
      uint32_t nb_essence_containers;
      int err;
  
      if ((err = av_reallocp_array(&mxf->partitions, mxf->partitions_count + 1,
                                   sizeof(*mxf->partitions))) < 0) {
          mxf->partitions_count = 0;
          return err;
      }
  
      if (mxf->parsing_backward) {
          /* insert the new partition pack in the middle
           * this makes the entries in mxf->partitions sorted by offset */
          memmove(&mxf->partitions[mxf->last_forward_partition+1],
                  &mxf->partitions[mxf->last_forward_partition],
                  (mxf->partitions_count - mxf->last_forward_partition)*sizeof(*mxf->partitions));
          partition = mxf->current_partition = &mxf->partitions[mxf->last_forward_partition];
      } else {
          mxf->last_forward_partition++;
          partition = mxf->current_partition = &mxf->partitions[mxf->partitions_count];
      }
  
      memset(partition, 0, sizeof(*partition));
      mxf->partitions_count++;
      partition->pack_length = avio_tell(pb) - klv_offset + size;
  
      switch(uid[13]) {
      case 2:
          partition->type = Header;
          break;
      case 3:
          partition->type = BodyPartition;
          break;
      case 4:
          partition->type = Footer;
          break;
      default:
          av_log(mxf->fc, AV_LOG_ERROR, "unknown partition type %i\n", uid[13]);
          return AVERROR_INVALIDDATA;
      }
  
      /* consider both footers to be closed (there is only Footer and CompleteFooter) */
      partition->closed = partition->type == Footer || !(uid[14] & 1);
      partition->complete = uid[14] > 2;
      avio_skip(pb, 4);
      partition->kag_size = avio_rb32(pb);
      partition->this_partition = avio_rb64(pb);
      partition->previous_partition = avio_rb64(pb);
      footer_partition = avio_rb64(pb);
      partition->header_byte_count = avio_rb64(pb);
      partition->index_byte_count = avio_rb64(pb);
      partition->index_sid = avio_rb32(pb);
      avio_skip(pb, 8);
      partition->body_sid = avio_rb32(pb);
      avio_read(pb, op, sizeof(UID));
      nb_essence_containers = avio_rb32(pb);
  
      if (partition->this_partition &&
          partition->previous_partition == partition->this_partition) {
          av_log(mxf->fc, AV_LOG_ERROR,
                 "PreviousPartition equal to ThisPartition %"PRIx64"\n",
                 partition->previous_partition);
          /* override with the actual previous partition offset */
          if (!mxf->parsing_backward && mxf->last_forward_partition > 1) {
              MXFPartition *prev =
                  mxf->partitions + mxf->last_forward_partition - 2;
              partition->previous_partition = prev->this_partition;
          }
          /* if no previous body partition are found point to the header
           * partition */
          if (partition->previous_partition == partition->this_partition)
              partition->previous_partition = 0;
          av_log(mxf->fc, AV_LOG_ERROR,
                 "Overriding PreviousPartition with %"PRIx64"\n",
                 partition->previous_partition);
      }
  
      /* some files don't have FooterPartition set in every partition */
      if (footer_partition) {
          if (mxf->footer_partition && mxf->footer_partition != footer_partition) {
              av_log(mxf->fc, AV_LOG_ERROR,
                     "inconsistent FooterPartition value: %"PRIu64" != %"PRIu64"\n",
                     mxf->footer_partition, footer_partition);
          } else {
              mxf->footer_partition = footer_partition;
          }
      }
  
      av_log(mxf->fc, AV_LOG_TRACE,
              "PartitionPack: ThisPartition = 0x%"PRIX64
              ", PreviousPartition = 0x%"PRIX64", "
              "FooterPartition = 0x%"PRIX64", IndexSID = %i, BodySID = %i\n",
              partition->this_partition,
              partition->previous_partition, footer_partition,
              partition->index_sid, partition->body_sid);
  
      /* sanity check PreviousPartition if set */
      if (partition->previous_partition &&
          mxf->run_in + partition->previous_partition >= klv_offset) {
          av_log(mxf->fc, AV_LOG_ERROR,
                 "PreviousPartition points to this partition or forward\n");
          return AVERROR_INVALIDDATA;
      }
  
      if      (op[12] == 1 && op[13] == 1) mxf->op = OP1a;
      else if (op[12] == 1 && op[13] == 2) mxf->op = OP1b;
      else if (op[12] == 1 && op[13] == 3) mxf->op = OP1c;
      else if (op[12] == 2 && op[13] == 1) mxf->op = OP2a;
      else if (op[12] == 2 && op[13] == 2) mxf->op = OP2b;
      else if (op[12] == 2 && op[13] == 3) mxf->op = OP2c;
      else if (op[12] == 3 && op[13] == 1) mxf->op = OP3a;
      else if (op[12] == 3 && op[13] == 2) mxf->op = OP3b;
      else if (op[12] == 3 && op[13] == 3) mxf->op = OP3c;
      else if (op[12] == 64&& op[13] == 1) mxf->op = OPSonyOpt;
      else if (op[12] == 0x10) {
          /* SMPTE 390m: "There shall be exactly one essence container"
           * The following block deals with files that violate this, namely:
           * 2011_DCPTEST_24FPS.V.mxf - two ECs, OP1a
           * abcdefghiv016f56415e.mxf - zero ECs, OPAtom, output by Avid AirSpeed */
          if (nb_essence_containers != 1) {
              MXFOP op = nb_essence_containers ? OP1a : OPAtom;
  
              /* only nag once */
              if (!mxf->op)
                  av_log(mxf->fc, AV_LOG_WARNING,
                         "\"OPAtom\" with %"PRIu32" ECs - assuming %s\n",
                         nb_essence_containers,
                         op == OP1a ? "OP1a" : "OPAtom");
  
              mxf->op = op;
          } else
              mxf->op = OPAtom;
      } else {
          av_log(mxf->fc, AV_LOG_ERROR, "unknown operational pattern: %02xh %02xh - guessing OP1a\n", op[12], op[13]);
          mxf->op = OP1a;
      }
  
      if (partition->kag_size <= 0 || partition->kag_size > (1 << 20)) {
          av_log(mxf->fc, AV_LOG_WARNING, "invalid KAGSize %"PRId32" - guessing ",
                 partition->kag_size);
  
          if (mxf->op == OPSonyOpt)
              partition->kag_size = 512;
          else
              partition->kag_size = 1;
  
          av_log(mxf->fc, AV_LOG_WARNING, "%"PRId32"\n", partition->kag_size);
      }
  
      return 0;
  }
  
  static int mxf_add_metadata_set(MXFContext *mxf, void *metadata_set)
  {
      int err;
  
      if ((err = av_reallocp_array(&mxf->metadata_sets, mxf->metadata_sets_count + 1,
                                   sizeof(*mxf->metadata_sets))) < 0) {
          mxf->metadata_sets_count = 0;
          return err;
      }
      mxf->metadata_sets[mxf->metadata_sets_count] = metadata_set;
      mxf->metadata_sets_count++;
      return 0;
  }
  
  static int mxf_read_cryptographic_context(void *arg, AVIOContext *pb, int tag, int size, UID uid, int64_t klv_offset)
  {
      MXFCryptoContext *cryptocontext = arg;
      if (size != 16)
          return AVERROR_INVALIDDATA;
      if (IS_KLV_KEY(uid, mxf_crypto_source_container_ul))
          avio_read(pb, cryptocontext->source_container_ul, 16);
      return 0;
  }
  
  static int mxf_read_content_storage(void *arg, AVIOContext *pb, int tag, int size, UID uid, int64_t klv_offset)
  {
      MXFContext *mxf = arg;
      switch (tag) {
      case 0x1901:
          mxf->packages_count = avio_rb32(pb);
          if (mxf->packages_count >= UINT_MAX / sizeof(UID))
              return AVERROR_INVALIDDATA;
          mxf->packages_refs = av_malloc(mxf->packages_count * sizeof(UID));
          if (!mxf->packages_refs)
              return AVERROR(ENOMEM);
          avio_skip(pb, 4); /* useless size of objects, always 16 according to specs */
          avio_read(pb, (uint8_t *)mxf->packages_refs, mxf->packages_count * sizeof(UID));
          break;
      }
      return 0;
  }
  
  static int mxf_read_source_clip(void *arg, AVIOContext *pb, int tag, int size, UID uid, int64_t klv_offset)
  {
      MXFStructuralComponent *source_clip = arg;
      switch(tag) {
      case 0x0202:
          source_clip->duration = avio_rb64(pb);
          break;
      case 0x1201:
          source_clip->start_position = avio_rb64(pb);
          break;
      case 0x1101:
          /* UMID, only get last 16 bytes */
          avio_skip(pb, 16);
          avio_read(pb, source_clip->source_package_uid, 16);
          break;
      case 0x1102:
          source_clip->source_track_id = avio_rb32(pb);
          break;
      }
      return 0;
  }
  
  static int mxf_read_material_package(void *arg, AVIOContext *pb, int tag, int size, UID uid, int64_t klv_offset)
  {
      MXFPackage *package = arg;
      switch(tag) {
      case 0x4403:
          package->tracks_count = avio_rb32(pb);
          if (package->tracks_count >= UINT_MAX / sizeof(UID))
              return AVERROR_INVALIDDATA;
          package->tracks_refs = av_malloc(package->tracks_count * sizeof(UID));
          if (!package->tracks_refs)
              return AVERROR(ENOMEM);
          avio_skip(pb, 4); /* useless size of objects, always 16 according to specs */
          avio_read(pb, (uint8_t *)package->tracks_refs, package->tracks_count * sizeof(UID));
          break;
      }
      return 0;
  }
  
  static int mxf_read_track(void *arg, AVIOContext *pb, int tag, int size, UID uid, int64_t klv_offset)
  {
      MXFTrack *track = arg;
      switch(tag) {
      case 0x4801:
          track->track_id = avio_rb32(pb);
          break;
      case 0x4804:
          avio_read(pb, track->track_number, 4);
          break;
      case 0x4b01:
          track->edit_rate.num = avio_rb32(pb);
          track->edit_rate.den = avio_rb32(pb);
          break;
      case 0x4803:
          avio_read(pb, track->sequence_ref, 16);
          break;
      }
      return 0;
  }
  
  static int mxf_read_sequence(void *arg, AVIOContext *pb, int tag, int size, UID uid, int64_t klv_offset)
  {
      MXFSequence *sequence = arg;
      switch(tag) {
      case 0x0202:
          sequence->duration = avio_rb64(pb);
          break;
      case 0x0201:
          avio_read(pb, sequence->data_definition_ul, 16);
          break;
          case 0x4b02:
          sequence->origin = avio_r8(pb);
          break;
      case 0x1001:
          sequence->structural_components_count = avio_rb32(pb);
          if (sequence->structural_components_count >= UINT_MAX / sizeof(UID))
              return AVERROR_INVALIDDATA;
          sequence->structural_components_refs = av_malloc(sequence->structural_components_count * sizeof(UID));
          if (!sequence->structural_components_refs)
              return AVERROR(ENOMEM);
          avio_skip(pb, 4); /* useless size of objects, always 16 according to specs */
          avio_read(pb, (uint8_t *)sequence->structural_components_refs, sequence->structural_components_count * sizeof(UID));
          break;
      }
      return 0;
  }
  
  static int mxf_read_source_package(void *arg, AVIOContext *pb, int tag, int size, UID uid, int64_t klv_offset)
  {
      MXFPackage *package = arg;
      switch(tag) {
      case 0x4403:
          package->tracks_count = avio_rb32(pb);
          if (package->tracks_count >= UINT_MAX / sizeof(UID))
              return AVERROR_INVALIDDATA;
          package->tracks_refs = av_malloc(package->tracks_count * sizeof(UID));
          if (!package->tracks_refs)
              return AVERROR(ENOMEM);
          avio_skip(pb, 4); /* useless size of objects, always 16 according to specs */
          avio_read(pb, (uint8_t *)package->tracks_refs, package->tracks_count * sizeof(UID));
          break;
      case 0x4401:
          /* UMID, only get last 16 bytes */
          avio_skip(pb, 16);
          avio_read(pb, package->package_uid, 16);
          break;
      case 0x4701:
          avio_read(pb, package->descriptor_ref, 16);
          break;
      }
      return 0;
  }
  
  static int mxf_read_index_entry_array(AVIOContext *pb, MXFIndexTableSegment *segment)
  {
      int i, length;
  
      segment->nb_index_entries = avio_rb32(pb);
      if (!segment->nb_index_entries)
          return 0;
      else if (segment->nb_index_entries < 0 ||
               segment->nb_index_entries >
               (INT_MAX / sizeof(*segment->stream_offset_entries)))
          return AVERROR(ENOMEM);
  
      length = avio_rb32(pb);
  
      segment->temporal_offset_entries = av_mallocz(segment->nb_index_entries *
                                   sizeof(*segment->temporal_offset_entries));
      segment->flag_entries            = av_mallocz(segment->nb_index_entries *
                                   sizeof(*segment->flag_entries));
      segment->stream_offset_entries   = av_mallocz(segment->nb_index_entries *
                                   sizeof(*segment->stream_offset_entries));
  
      if (!segment->flag_entries || !segment->stream_offset_entries ||
          !segment->temporal_offset_entries) {
          av_freep(&segment->flag_entries);
          av_freep(&segment->stream_offset_entries);
          av_freep(&segment->temporal_offset_entries);
          return AVERROR(ENOMEM);
      }
  
      for (i = 0; i < segment->nb_index_entries; i++) {
          segment->temporal_offset_entries[i] = avio_r8(pb);
          avio_r8(pb);                                        /* KeyFrameOffset */
          segment->flag_entries[i] = avio_r8(pb);
          segment->stream_offset_entries[i] = avio_rb64(pb);
          avio_skip(pb, length - 11);
      }
      return 0;
  }
  
  static int mxf_read_index_table_segment(void *arg, AVIOContext *pb, int tag, int size, UID uid, int64_t klv_offset)
  {
      MXFIndexTableSegment *segment = arg;
      switch(tag) {
      case 0x3F05:
          segment->edit_unit_byte_count = avio_rb32(pb);
          av_log(NULL, AV_LOG_TRACE, "EditUnitByteCount %d\n", segment->edit_unit_byte_count);
          break;
      case 0x3F06:
          segment->index_sid = avio_rb32(pb);
          av_log(NULL, AV_LOG_TRACE, "IndexSID %d\n", segment->index_sid);
          break;
      case 0x3F07:
          segment->body_sid = avio_rb32(pb);
          av_log(NULL, AV_LOG_TRACE, "BodySID %d\n", segment->body_sid);
          break;
      case 0x3F0A:
          av_log(NULL, AV_LOG_TRACE, "IndexEntryArray found\n");
          return mxf_read_index_entry_array(pb, segment);
      case 0x3F0B:
          segment->index_edit_rate.num = avio_rb32(pb);
          segment->index_edit_rate.den = avio_rb32(pb);
          av_log(NULL, AV_LOG_TRACE, "IndexEditRate %d/%d\n", segment->index_edit_rate.num,
                  segment->index_edit_rate.den);
          break;
      case 0x3F0C:
          segment->index_start_position = avio_rb64(pb);
          av_log(NULL, AV_LOG_TRACE, "IndexStartPosition %"PRId64"\n", segment->index_start_position);
          break;
      case 0x3F0D:
          segment->index_duration = avio_rb64(pb);
          av_log(NULL, AV_LOG_TRACE, "IndexDuration %"PRId64"\n", segment->index_duration);
          break;
      }
      return 0;
  }
  
  static void mxf_read_pixel_layout(AVIOContext *pb, MXFDescriptor *descriptor)
  {
      int code, value, ofs = 0;
      char layout[16] = {0};
  
      do {
          code = avio_r8(pb);
          value = avio_r8(pb);
          av_log(NULL, AV_LOG_TRACE, "pixel layout: code %#x\n", code);
  
          if (ofs <= 14) {
              layout[ofs++] = code;
              layout[ofs++] = value;
          }
      } while (code != 0); /* SMPTE 377M E.2.46 */
  
      ff_mxf_decode_pixel_layout(layout, &descriptor->pix_fmt);
  }
  
  static int mxf_read_generic_descriptor(void *arg, AVIOContext *pb, int tag, int size, UID uid, int64_t klv_offset)
  {
      MXFDescriptor *descriptor = arg;
      descriptor->pix_fmt = AV_PIX_FMT_NONE;
      switch(tag) {
      case 0x3F01:
          descriptor->sub_descriptors_count = avio_rb32(pb);
          if (descriptor->sub_descriptors_count >= UINT_MAX / sizeof(UID))
              return AVERROR_INVALIDDATA;
          descriptor->sub_descriptors_refs = av_malloc(descriptor->sub_descriptors_count * sizeof(UID));
          if (!descriptor->sub_descriptors_refs)
              return AVERROR(ENOMEM);
          avio_skip(pb, 4); /* useless size of objects, always 16 according to specs */
          avio_read(pb, (uint8_t *)descriptor->sub_descriptors_refs, descriptor->sub_descriptors_count * sizeof(UID));
          break;
      case 0x3004:
          avio_read(pb, descriptor->essence_container_ul, 16);
          break;
      case 0x3006:
          descriptor->linked_track_id = avio_rb32(pb);
          break;
      case 0x3201: /* PictureEssenceCoding */
          avio_read(pb, descriptor->essence_codec_ul, 16);
          break;
      case 0x3203:
          descriptor->width = avio_rb32(pb);
          break;
      case 0x3202:
          descriptor->height = avio_rb32(pb);
          break;
      case 0x320C:
          descriptor->frame_layout = avio_r8(pb);
          break;
      case 0x320E:
          descriptor->aspect_ratio.num = avio_rb32(pb);
          descriptor->aspect_ratio.den = avio_rb32(pb);
          break;
      case 0x3212:
          descriptor->field_dominance = avio_r8(pb);
          break;
      case 0x3301:
          descriptor->component_depth = avio_rb32(pb);
          break;
      case 0x3302:
          descriptor->horiz_subsampling = avio_rb32(pb);
          break;
      case 0x3308:
          descriptor->vert_subsampling = avio_rb32(pb);
          break;
      case 0x3D03:
          descriptor->sample_rate.num = avio_rb32(pb);
          descriptor->sample_rate.den = avio_rb32(pb);
          break;
      case 0x3D06: /* SoundEssenceCompression */
          avio_read(pb, descriptor->essence_codec_ul, 16);
          break;
      case 0x3D07:
          descriptor->channels = avio_rb32(pb);
          break;
      case 0x3D01:
          descriptor->bits_per_sample = avio_rb32(pb);
          break;
      case 0x3401:
          mxf_read_pixel_layout(pb, descriptor);
          break;
      default:
          /* Private uid used by SONY C0023S01.mxf */
          if (IS_KLV_KEY(uid, mxf_sony_mpeg4_extradata)) {
              av_free(descriptor->extradata);
              descriptor->extradata_size = 0;
              descriptor->extradata = av_malloc(size + AV_INPUT_BUFFER_PADDING_SIZE);
              if (!descriptor->extradata)
                  return AVERROR(ENOMEM);
              descriptor->extradata_size = size;
              avio_read(pb, descriptor->extradata, size);
          }
          break;
      }
      return 0;
  }
  
  /*
   * Match an uid independently of the version byte and up to len common bytes
   * Returns: boolean
   */
  static int mxf_match_uid(const UID key, const UID uid, int len)
  {
      int i;
      for (i = 0; i < len; i++) {
          if (i != 7 && key[i] != uid[i])
              return 0;
      }
      return 1;
  }
  
  static const MXFCodecUL *mxf_get_codec_ul(const MXFCodecUL *uls, UID *uid)
  {
      while (uls->uid[0]) {
          if(mxf_match_uid(uls->uid, *uid, uls->matching_len))
              break;
          uls++;
      }
      return uls;
  }
  
  static void *mxf_resolve_strong_ref(MXFContext *mxf, UID *strong_ref, enum MXFMetadataSetType type)
  {
      int i;
  
      if (!strong_ref)
          return NULL;
      for (i = 0; i < mxf->metadata_sets_count; i++) {
          if (!memcmp(*strong_ref, mxf->metadata_sets[i]->uid, 16) &&
              (type == AnyType || mxf->metadata_sets[i]->type == type)) {
              return mxf->metadata_sets[i];
          }
      }
      return NULL;
  }
  
  static const MXFCodecUL mxf_picture_essence_container_uls[] = {
      // video essence container uls
      { { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x02,0x0d,0x01,0x03,0x01,0x02,0x04,0x60,0x01 }, 14, AV_CODEC_ID_MPEG2VIDEO }, /* MPEG-ES frame-wrapped */
      { { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x01,0x0d,0x01,0x03,0x01,0x02,0x02,0x41,0x01 }, 14,    AV_CODEC_ID_DVVIDEO }, /* DV 625 25mbps */
      { { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x01,0x0d,0x01,0x03,0x01,0x02,0x05,0x00,0x00 }, 14,   AV_CODEC_ID_RAWVIDEO }, /* uncompressed picture */
      { { 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 },  0,      AV_CODEC_ID_NONE },
  };
  
  /* EC ULs for intra-only formats */
  static const MXFCodecUL mxf_intra_only_essence_container_uls[] = {
      { { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x01,0x0d,0x01,0x03,0x01,0x02,0x01,0x00,0x00 }, 14, AV_CODEC_ID_MPEG2VIDEO }, /* MXF-GC SMPTE D-10 mappings */
      { { 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 },  0,       AV_CODEC_ID_NONE },
  };
  
  /* intra-only PictureEssenceCoding ULs, where no corresponding EC UL exists */
  static const MXFCodecUL mxf_intra_only_picture_essence_coding_uls[] = {
      { { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x0A,0x04,0x01,0x02,0x02,0x01,0x32,0x00,0x00 }, 14,       AV_CODEC_ID_H264 }, /* H.264/MPEG-4 AVC Intra Profiles */
      { { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x07,0x04,0x01,0x02,0x02,0x03,0x01,0x01,0x00 }, 14,   AV_CODEC_ID_JPEG2000 }, /* JPEG 2000 code stream */
      { { 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 },  0,       AV_CODEC_ID_NONE },
  };
  
  static const MXFCodecUL mxf_sound_essence_container_uls[] = {
      // sound essence container uls
      { { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x01,0x0d,0x01,0x03,0x01,0x02,0x06,0x01,0x00 }, 14, AV_CODEC_ID_PCM_S16LE }, /* BWF Frame wrapped */
      { { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x02,0x0d,0x01,0x03,0x01,0x02,0x04,0x40,0x01 }, 14,       AV_CODEC_ID_MP2 }, /* MPEG-ES Frame wrapped, 0x40 ??? stream id */
      { { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x01,0x0d,0x01,0x03,0x01,0x02,0x01,0x01,0x01 }, 14, AV_CODEC_ID_PCM_S16LE }, /* D-10 Mapping 50Mbps PAL Extended Template */
      { { 0x06,0x0e,0x2b,0x34,0x01,0x01,0x01,0xff,0x4b,0x46,0x41,0x41,0x00,0x0d,0x4d,0x4F }, 14, AV_CODEC_ID_PCM_S16LE }, /* 0001GL00.MXF.A1.mxf_opatom.mxf */
      { { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x03,0x04,0x02,0x02,0x02,0x03,0x03,0x01,0x00 }, 14,       AV_CODEC_ID_AAC }, /* MPEG-2 AAC ADTS (legacy) */
      { { 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 },  0,      AV_CODEC_ID_NONE },
  };
  
  static const MXFCodecUL mxf_data_essence_container_uls[] = {
      { { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x09,0x0d,0x01,0x03,0x01,0x02,0x0e,0x00,0x00 }, 16, 0 },
      { { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x09,0x0d,0x01,0x03,0x01,0x02,0x0e,0x00,0x00 }, 16, AV_CODEC_ID_NONE },
  };
  
  static const char* mxf_data_essence_descriptor[] = {
      "vbi_vanc_smpte_436M",
  };
  
  static int mxf_get_sorted_table_segments(MXFContext *mxf, int *nb_sorted_segments, MXFIndexTableSegment ***sorted_segments)
  {
      int i, j, nb_segments = 0;
      MXFIndexTableSegment **unsorted_segments;
      int last_body_sid = -1, last_index_sid = -1, last_index_start = -1;
  
      /* count number of segments, allocate arrays and copy unsorted segments */
      for (i = 0; i < mxf->metadata_sets_count; i++)
          if (mxf->metadata_sets[i]->type == IndexTableSegment)
              nb_segments++;
  
      if (!nb_segments)
          return AVERROR_INVALIDDATA;
  
      *sorted_segments  = av_mallocz(nb_segments * sizeof(**sorted_segments));
      unsorted_segments = av_mallocz(nb_segments * sizeof(*unsorted_segments));
      if (!*sorted_segments || !unsorted_segments) {
          av_freep(sorted_segments);
          av_free(unsorted_segments);
          return AVERROR(ENOMEM);
      }
  
      for (i = j = 0; i < mxf->metadata_sets_count; i++)
          if (mxf->metadata_sets[i]->type == IndexTableSegment)
              unsorted_segments[j++] = (MXFIndexTableSegment*)mxf->metadata_sets[i];
  
      *nb_sorted_segments = 0;
  
      /* sort segments by {BodySID, IndexSID, IndexStartPosition}, remove duplicates while we're at it */
      for (i = 0; i < nb_segments; i++) {
          int best = -1, best_body_sid = -1, best_index_sid = -1, best_index_start = -1;
          uint64_t best_index_duration = 0;
  
          for (j = 0; j < nb_segments; j++) {
              MXFIndexTableSegment *s = unsorted_segments[j];
  
              /* Require larger BosySID, IndexSID or IndexStartPosition then the previous entry. This removes duplicates.
               * We want the smallest values for the keys than what we currently have, unless this is the first such entry this time around.
               * If we come across an entry with the same IndexStartPosition but larger IndexDuration, then we'll prefer it over the one we currently have.
               */
              if ((i == 0     || s->body_sid > last_body_sid || s->index_sid > last_index_sid || s->index_start_position > last_index_start) &&
                  (best == -1 || s->body_sid < best_body_sid || s->index_sid < best_index_sid || s->index_start_position < best_index_start ||
                  (s->index_start_position == best_index_start && s->index_duration > best_index_duration))) {
                  best             = j;
                  best_body_sid    = s->body_sid;
                  best_index_sid   = s->index_sid;
                  best_index_start = s->index_start_position;
                  best_index_duration = s->index_duration;
              }
          }
  
          /* no suitable entry found -> we're done */
          if (best == -1)
              break;
  
          (*sorted_segments)[(*nb_sorted_segments)++] = unsorted_segments[best];
          last_body_sid    = best_body_sid;
          last_index_sid   = best_index_sid;
          last_index_start = best_index_start;
      }
  
      av_free(unsorted_segments);
  
      return 0;
  }
  
  /**
   * Computes the absolute file offset of the given essence container offset
   */
  static int mxf_absolute_bodysid_offset(MXFContext *mxf, int body_sid, int64_t offset, int64_t *offset_out)
  {
      int x;
      int64_t offset_in = offset;     /* for logging */
  
      for (x = 0; x < mxf->partitions_count; x++) {
          MXFPartition *p = &mxf->partitions[x];
  
          if (p->body_sid != body_sid)
              continue;
  
          if (offset < p->essence_length || !p->essence_length) {
              *offset_out = p->essence_offset + offset;
              return 0;
          }
  
          offset -= p->essence_length;
      }
  
      av_log(mxf->fc, AV_LOG_ERROR,
             "failed to find absolute offset of %"PRIX64" in BodySID %i - partial file?\n",
             offset_in, body_sid);
  
      return AVERROR_INVALIDDATA;
  }
  
  /**
   * Returns the end position of the essence container with given BodySID, or zero if unknown
   */
  static int64_t mxf_essence_container_end(MXFContext *mxf, int body_sid)
  {
      int x;
      int64_t ret = 0;
  
      for (x = 0; x < mxf->partitions_count; x++) {
          MXFPartition *p = &mxf->partitions[x];
  
          if (p->body_sid != body_sid)
              continue;
  
          if (!p->essence_length)
              return 0;
  
          ret = p->essence_offset + p->essence_length;
      }
  
      return ret;
  }
  
  /* EditUnit -> absolute offset */
  static int mxf_edit_unit_absolute_offset(MXFContext *mxf, MXFIndexTable *index_table, int64_t edit_unit, int64_t *edit_unit_out, int64_t *offset_out, int nag)
  {
      int i;
      int64_t offset_temp = 0;
  
      for (i = 0; i < index_table->nb_segments; i++) {
          MXFIndexTableSegment *s = index_table->segments[i];
  
          edit_unit = FFMAX(edit_unit, s->index_start_position);  /* clamp if trying to seek before start */
  
          if (edit_unit < s->index_start_position + s->index_duration) {
              int64_t index = edit_unit - s->index_start_position;
  
              if (s->edit_unit_byte_count)
                  offset_temp += s->edit_unit_byte_count * index;
              else if (s->nb_index_entries) {
                  if (s->nb_index_entries == 2 * s->index_duration + 1)
                      index *= 2;     /* Avid index */
  
                  if (index < 0 || index >= s->nb_index_entries) {
                      av_log(mxf->fc, AV_LOG_ERROR, "IndexSID %i segment at %"PRId64" IndexEntryArray too small\n",
                             index_table->index_sid, s->index_start_position);
                      return AVERROR_INVALIDDATA;
                  }
  
                  offset_temp = s->stream_offset_entries[index];
              } else {
                  av_log(mxf->fc, AV_LOG_ERROR, "IndexSID %i segment at %"PRId64" missing EditUnitByteCount and IndexEntryArray\n",
                         index_table->index_sid, s->index_start_position);
                  return AVERROR_INVALIDDATA;
              }
  
              if (edit_unit_out)
                  *edit_unit_out = edit_unit;
  
              return mxf_absolute_bodysid_offset(mxf, index_table->body_sid, offset_temp, offset_out);
          } else {
              /* EditUnitByteCount == 0 for VBR indexes, which is fine since they use explicit StreamOffsets */
              offset_temp += s->edit_unit_byte_count * s->index_duration;
          }
      }
  
      if (nag)
          av_log(mxf->fc, AV_LOG_ERROR, "failed to map EditUnit %"PRId64" in IndexSID %i to an offset\n", edit_unit, index_table->index_sid);
  
      return AVERROR_INVALIDDATA;
  }
  
  static int mxf_compute_ptses_fake_index(MXFContext *mxf, MXFIndexTable *index_table)
  {
      int i, j, x;
      int8_t max_temporal_offset = -128;
  
      /* first compute how many entries we have */
      for (i = 0; i < index_table->nb_segments; i++) {
          MXFIndexTableSegment *s = index_table->segments[i];
  
          if (!s->nb_index_entries) {
              index_table->nb_ptses = 0;
              return 0;                               /* no TemporalOffsets */
          }
  
          index_table->nb_ptses += s->index_duration;
      }
  
      /* paranoid check */
      if (index_table->nb_ptses <= 0)
          return 0;
  
      if (index_table->nb_ptses > INT_MAX / sizeof(AVIndexEntry))
          return AVERROR(ENOMEM);
  
      index_table->ptses      = av_mallocz(index_table->nb_ptses *
                                           sizeof(int64_t));
      index_table->fake_index = av_mallocz(index_table->nb_ptses *
                                           sizeof(AVIndexEntry));
      if (!index_table->ptses || !index_table->fake_index) {
          av_freep(&index_table->ptses);
          return AVERROR(ENOMEM);
      }
  
      /* we may have a few bad TemporalOffsets
       * make sure the corresponding PTSes don't have the bogus value 0 */
      for (x = 0; x < index_table->nb_ptses; x++)
          index_table->ptses[x] = AV_NOPTS_VALUE;
  
      /**
       * We have this:
       *
       * x  TemporalOffset
       * 0:  0
       * 1:  1
       * 2:  1
       * 3: -2
       * 4:  1
       * 5:  1
       * 6: -2
       *
       * We want to transform it into this:
       *
       * x  DTS PTS
       * 0: -1   0
       * 1:  0   3
       * 2:  1   1
       * 3:  2   2
       * 4:  3   6
       * 5:  4   4
       * 6:  5   5
       *
       * We do this by bucket sorting x by x+TemporalOffset[x] into mxf->ptses,
       * then settings mxf->first_dts = -max(TemporalOffset[x]).
       * The latter makes DTS <= PTS.
       */
      for (i = x = 0; i < index_table->nb_segments; i++) {
          MXFIndexTableSegment *s = index_table->segments[i];
          int index_delta = 1;
          int n = s->nb_index_entries;
  
          if (s->nb_index_entries == 2 * s->index_duration + 1) {
              index_delta = 2;    /* Avid index */
              /* ignore the last entry - it's the size of the essence container */
              n--;
          }
  
          for (j = 0; j < n; j += index_delta, x++) {
              int offset = s->temporal_offset_entries[j] / index_delta;
              int index  = x + offset;
  
              if (x >= index_table->nb_ptses) {
                  av_log(mxf->fc, AV_LOG_ERROR,
                         "x >= nb_ptses - IndexEntryCount %i < IndexDuration %"PRId64"?\n",
                         s->nb_index_entries, s->index_duration);
                  break;
              }
  
              index_table->fake_index[x].timestamp = x;
              index_table->fake_index[x].flags = !(s->flag_entries[j] & 0x30) ? AVINDEX_KEYFRAME : 0;
  
              if (index < 0 || index >= index_table->nb_ptses) {
                  av_log(mxf->fc, AV_LOG_ERROR,
                         "index entry %i + TemporalOffset %i = %i, which is out of bounds\n",
                         x, offset, index);
                  continue;
              }
  
              index_table->ptses[index] = x;
              max_temporal_offset = FFMAX(max_temporal_offset, offset);
          }
      }
  
      index_table->first_dts = -max_temporal_offset;
  
      return 0;
  }
  
  /**
   * Sorts and collects index table segments into index tables.
   * Also computes PTSes if possible.
   */
  static int mxf_compute_index_tables(MXFContext *mxf)
  {
      int i, j, k, ret, nb_sorted_segments;
      MXFIndexTableSegment **sorted_segments = NULL;
  
      if ((ret = mxf_get_sorted_table_segments(mxf, &nb_sorted_segments, &sorted_segments)) ||
          nb_sorted_segments <= 0) {
          av_log(mxf->fc, AV_LOG_WARNING, "broken or empty index\n");
          return 0;
      }
  
      /* sanity check and count unique BodySIDs/IndexSIDs */
      for (i = 0; i < nb_sorted_segments; i++) {
          if (i == 0 || sorted_segments[i-1]->index_sid != sorted_segments[i]->index_sid)
              mxf->nb_index_tables++;
          else if (sorted_segments[i-1]->body_sid != sorted_segments[i]->body_sid) {
              av_log(mxf->fc, AV_LOG_ERROR, "found inconsistent BodySID\n");
              ret = AVERROR_INVALIDDATA;
              goto finish_decoding_index;
          }
      }
  
      mxf->index_tables = av_mallocz_array(mxf->nb_index_tables,
                                           sizeof(*mxf->index_tables));
      if (!mxf->index_tables) {
          av_log(mxf->fc, AV_LOG_ERROR, "failed to allocate index tables\n");
          ret = AVERROR(ENOMEM);
          goto finish_decoding_index;
      }
  
      /* distribute sorted segments to index tables */
      for (i = j = 0; i < nb_sorted_segments; i++) {
          if (i != 0 && sorted_segments[i-1]->index_sid != sorted_segments[i]->index_sid) {
              /* next IndexSID */
              j++;
          }
  
          mxf->index_tables[j].nb_segments++;
      }
  
      for (i = j = 0; j < mxf->nb_index_tables; i += mxf->index_tables[j++].nb_segments) {
          MXFIndexTable *t = &mxf->index_tables[j];
  
          t->segments = av_mallocz_array(t->nb_segments,
                                         sizeof(*t->segments));
  
          if (!t->segments) {
              av_log(mxf->fc, AV_LOG_ERROR, "failed to allocate IndexTableSegment"
                     " pointer array\n");
              ret = AVERROR(ENOMEM);
              goto finish_decoding_index;
          }
  
          if (sorted_segments[i]->index_start_position)
              av_log(mxf->fc, AV_LOG_WARNING, "IndexSID %i starts at EditUnit %"PRId64" - seeking may not work as expected\n",
                     sorted_segments[i]->index_sid, sorted_segments[i]->index_start_position);
  
          memcpy(t->segments, &sorted_segments[i], t->nb_segments * sizeof(MXFIndexTableSegment*));
          t->index_sid = sorted_segments[i]->index_sid;
          t->body_sid = sorted_segments[i]->body_sid;
  
          if ((ret = mxf_compute_ptses_fake_index(mxf, t)) < 0)
              goto finish_decoding_index;
  
          /* fix zero IndexDurations */
          for (k = 0; k < t->nb_segments; k++) {
              if (t->segments[k]->index_duration)
                  continue;
  
              if (t->nb_segments > 1)
                  av_log(mxf->fc, AV_LOG_WARNING, "IndexSID %i segment %i has zero IndexDuration and there's more than one segment\n",
                         t->index_sid, k);
  
              if (mxf->fc->nb_streams <= 0) {
                  av_log(mxf->fc, AV_LOG_WARNING, "no streams?\n");
                  break;
              }
  
              /* assume the first stream's duration is reasonable
               * leave index_duration = 0 on further segments in case we have any (unlikely)
               */
              t->segments[k]->index_duration = mxf->fc->streams[0]->duration;
              break;
          }
      }
  
      ret = 0;
  finish_decoding_index:
      av_free(sorted_segments);
      return ret;
  }
  
  static int mxf_is_intra_only(MXFDescriptor *d)
  {
      return mxf_get_codec_ul(mxf_intra_only_essence_container_uls,
                              &d->essence_container_ul)->id != AV_CODEC_ID_NONE ||
             mxf_get_codec_ul(mxf_intra_only_picture_essence_coding_uls,
                              &d->essence_codec_ul)->id     != AV_CODEC_ID_NONE;
  }
  
  static int mxf_parse_structural_metadata(MXFContext *mxf)
  {
      MXFPackage *material_package = NULL;
      MXFPackage *temp_package = NULL;
      int i, j, k, ret;
  
      av_log(mxf->fc, AV_LOG_TRACE, "metadata sets count %d\n", mxf->metadata_sets_count);
      /* TODO: handle multiple material packages (OP3x) */
      for (i = 0; i < mxf->packages_count; i++) {
          material_package = mxf_resolve_strong_ref(mxf, &mxf->packages_refs[i], MaterialPackage);
          if (material_package) break;
      }
      if (!material_package) {
          av_log(mxf->fc, AV_LOG_ERROR, "no material package found\n");
          return AVERROR_INVALIDDATA;
      }
  
      for (i = 0; i < material_package->tracks_count; i++) {
          MXFPackage *source_package = NULL;
          MXFTrack *material_track = NULL;
          MXFTrack *source_track = NULL;
          MXFTrack *temp_track = NULL;
          MXFDescriptor *descriptor = NULL;
          MXFStructuralComponent *component = NULL;
          UID *essence_container_ul = NULL;
          const MXFCodecUL *codec_ul = NULL;
          const MXFCodecUL *container_ul = NULL;
          const MXFCodecUL *pix_fmt_ul = NULL;
          AVStream *st;
  
          if (!(material_track = mxf_resolve_strong_ref(mxf, &material_package->tracks_refs[i], Track))) {
              av_log(mxf->fc, AV_LOG_ERROR, "could not resolve material track strong ref\n");
              continue;
          }
  
          if (!(material_track->sequence = mxf_resolve_strong_ref(mxf, &material_track->sequence_ref, Sequence))) {
              av_log(mxf->fc, AV_LOG_ERROR, "could not resolve material track sequence strong ref\n");
              continue;
          }
  
          /* TODO: handle multiple source clips */
          for (j = 0; j < material_track->sequence->structural_components_count; j++) {
              /* TODO: handle timecode component */
              component = mxf_resolve_strong_ref(mxf, &material_track->sequence->structural_components_refs[j], SourceClip);
              if (!component)
                  continue;
  
              for (k = 0; k < mxf->packages_count; k++) {
                  temp_package = mxf_resolve_strong_ref(mxf, &mxf->packages_refs[k], SourcePackage);
                  if (!temp_package)
                      continue;
                  if (!memcmp(temp_package->package_uid, component->source_package_uid, 16)) {
                      source_package = temp_package;
                      break;
                  }
              }
              if (!source_package) {
                  av_log(mxf->fc, AV_LOG_TRACE, "material track %d: no corresponding source package found\n", material_track->track_id);
                  break;
              }
              for (k = 0; k < source_package->tracks_count; k++) {
                  if (!(temp_track = mxf_resolve_strong_ref(mxf, &source_package->tracks_refs[k], Track))) {
                      av_log(mxf->fc, AV_LOG_ERROR, "could not resolve source track strong ref\n");
                      ret = AVERROR_INVALIDDATA;
                      goto fail_and_free;
                  }
                  if (temp_track->track_id == component->source_track_id) {
                      source_track = temp_track;
                      break;
                  }
              }
              if (!source_track) {
                  av_log(mxf->fc, AV_LOG_ERROR, "material track %d: no corresponding source track found\n", material_track->track_id);
                  break;
              }
          }
          if (!source_track || !component)
              continue;
  
          if (!(source_track->sequence = mxf_resolve_strong_ref(mxf, &source_track->sequence_ref, Sequence))) {
              av_log(mxf->fc, AV_LOG_ERROR, "could not resolve source track sequence strong ref\n");
              ret = AVERROR_INVALIDDATA;
              goto fail_and_free;
          }
  
          /* 0001GL00.MXF.A1.mxf_opatom.mxf has the same SourcePackageID as 0001GL.MXF.V1.mxf_opatom.mxf
           * This would result in both files appearing to have two streams. Work around this by sanity checking DataDefinition */
          if (memcmp(material_track->sequence->data_definition_ul, source_track->sequence->data_definition_ul, 16)) {
              av_log(mxf->fc, AV_LOG_ERROR, "material track %d: DataDefinition mismatch\n", material_track->track_id);
              continue;
          }
  
          st = avformat_new_stream(mxf->fc, NULL);
          if (!st) {
              av_log(mxf->fc, AV_LOG_ERROR, "could not allocate stream\n");
              ret = AVERROR(ENOMEM);
              goto fail_and_free;
          }
          st->id = source_track->track_id;
          st->priv_data = source_track;
          source_track->original_duration = st->duration = component->duration;
          if (st->duration == -1)
              st->duration = AV_NOPTS_VALUE;
          st->start_time = component->start_position;
          if (material_track->edit_rate.num <= 0 ||
              material_track->edit_rate.den <= 0) {
              av_log(mxf->fc, AV_LOG_WARNING,
                     "Invalid edit rate (%d/%d) found on stream #%d, "
                     "defaulting to 25/1\n",
                     material_track->edit_rate.num,
                     material_track->edit_rate.den, st->index);
              material_track->edit_rate = (AVRational){25, 1};
          }
          avpriv_set_pts_info(st, 64, material_track->edit_rate.den, material_track->edit_rate.num);
  
          /* ensure SourceTrack EditRate == MaterialTrack EditRate since only
           * the former is accessible via st->priv_data */
          source_track->edit_rate = material_track->edit_rate;
  
          PRINT_KEY(mxf->fc, "data definition   ul", source_track->sequence->data_definition_ul);
          codec_ul = mxf_get_codec_ul(ff_mxf_data_definition_uls, &source_track->sequence->data_definition_ul);
          st->codecpar->codec_type = codec_ul->id;
  
          source_package->descriptor = mxf_resolve_strong_ref(mxf, &source_package->descriptor_ref, AnyType);
          if (source_package->descriptor) {
              if (source_package->descriptor->type == MultipleDescriptor) {
                  for (j = 0; j < source_package->descriptor->sub_descriptors_count; j++) {
                      MXFDescriptor *sub_descriptor = mxf_resolve_strong_ref(mxf, &source_package->descriptor->sub_descriptors_refs[j], Descriptor);
  
                      if (!sub_descriptor) {
                          av_log(mxf->fc, AV_LOG_ERROR, "could not resolve sub descriptor strong ref\n");
                          continue;
                      }
                      if (sub_descriptor->linked_track_id == source_track->track_id) {
                          descriptor = sub_descriptor;
                          break;
                      }
                  }
              } else if (source_package->descriptor->type == Descriptor)
                  descriptor = source_package->descriptor;
          }
          if (!descriptor) {
              av_log(mxf->fc, AV_LOG_INFO, "source track %d: stream %d, no descriptor found\n", source_track->track_id, st->index);
              continue;
          }
          PRINT_KEY(mxf->fc, "essence codec     ul", descriptor->essence_codec_ul);
          PRINT_KEY(mxf->fc, "essence container ul", descriptor->essence_container_ul);
          essence_container_ul = &descriptor->essence_container_ul;
          /* HACK: replacing the original key with mxf_encrypted_essence_container
           * is not allowed according to s429-6, try to find correct information anyway */
          if (IS_KLV_KEY(essence_container_ul, mxf_encrypted_essence_container)) {
              av_log(mxf->fc, AV_LOG_INFO, "broken encrypted mxf file\n");
              for (k = 0; k < mxf->metadata_sets_count; k++) {
                  MXFMetadataSet *metadata = mxf->metadata_sets[k];
                  if (metadata->type == CryptoContext) {
                      essence_container_ul = &((MXFCryptoContext *)metadata)->source_container_ul;
                      break;
                  }
              }
          }
  
          /* TODO: drop PictureEssenceCoding and SoundEssenceCompression, only check EssenceContainer */
          codec_ul = mxf_get_codec_ul(ff_mxf_codec_uls, &descriptor->essence_codec_ul);
          st->codecpar->codec_id = codec_ul->id;
  
          if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
              source_track->intra_only = mxf_is_intra_only(descriptor);
              container_ul = mxf_get_codec_ul(mxf_picture_essence_container_uls, essence_container_ul);
              if (st->codecpar->codec_id == AV_CODEC_ID_NONE)
                  st->codecpar->codec_id = container_ul->id;
              st->codecpar->width = descriptor->width;
              /* Field height, not frame height */
              st->codecpar->height = descriptor->height;
              switch (descriptor->frame_layout) {
                  case SegmentedFrame:
                      /* This one is a weird layout I don't fully understand. */
                      av_log(mxf->fc, AV_LOG_INFO,
                             "SegmentedFrame layout isn't currently supported\n");
                      break;
                  case FullFrame:
                      st->codecpar->field_order = AV_FIELD_PROGRESSIVE;
                      break;
                  case OneField:
                      /* Every other line is stored and needs to be duplicated. */
                      av_log(mxf->fc, AV_LOG_INFO,
                             "OneField frame layout isn't currently supported\n");
                      break;
                      /* The correct thing to do here is fall through, but by
                       * breaking we might be able to decode some streams at half
                       * the vertical resolution, rather than not al all.
                       * It's also for compatibility with the old behavior. */
                  case SeparateFields:
                  case MixedFields:
                      switch (descriptor->field_dominance) {
                      case MXF_TFF:
                          st->codecpar->field_order = AV_FIELD_TT;
                          break;
                      case MXF_BFF:
                          st->codecpar->field_order = AV_FIELD_BB;
                          break;
                      default:
                          avpriv_request_sample(mxf->fc,
                                                "Field dominance %d support",
                                                descriptor->field_dominance);
                          break;
                      }
                      /* Turn field height into frame height. */
                      st->codecpar->height *= 2;
                      break;
                  default:
                      av_log(mxf->fc, AV_LOG_INFO,
                             "Unknown frame layout type: %d\n",
                             descriptor->frame_layout);
              }
              if (st->codecpar->codec_id == AV_CODEC_ID_RAWVIDEO) {
                  st->codecpar->format = descriptor->pix_fmt;
                  if (st->codecpar->format == AV_PIX_FMT_NONE) {
                      pix_fmt_ul = mxf_get_codec_ul(ff_mxf_pixel_format_uls,
                                                    &descriptor->essence_codec_ul);
                      st->codecpar->format = pix_fmt_ul->id;
                      if (st->codecpar->format == AV_PIX_FMT_NONE) {
                          /* support files created before RP224v10 by defaulting to UYVY422
                             if subsampling is 4:2:2 and component depth is 8-bit */
                          if (descriptor->horiz_subsampling == 2 &&
                              descriptor->vert_subsampling == 1 &&
                              descriptor->component_depth == 8) {
                              st->codecpar->format = AV_PIX_FMT_UYVY422;
                          }
                      }
                  }
              }
              st->need_parsing = AVSTREAM_PARSE_HEADERS;
              if (material_track->sequence->origin) {
                  char material_origin[3];
                  snprintf(material_origin, sizeof(material_origin), "%d", material_track->sequence->origin);
                  av_dict_set(&st->metadata, "material_track_origin", material_origin, 0);
              }
              if (source_track->sequence->origin) {
                  char source_origin[3];
                  snprintf(source_origin, sizeof(source_origin), "%d", source_track->sequence->origin);
                  av_dict_set(&st->metadata, "source_track_origin", source_origin, 0);
              }
          } else if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
              container_ul = mxf_get_codec_ul(mxf_sound_essence_container_uls, essence_container_ul);
              if (st->codecpar->codec_id == AV_CODEC_ID_NONE)
                  st->codecpar->codec_id = container_ul->id;
              st->codecpar->channels = descriptor->channels;
              st->codecpar->bits_per_coded_sample = descriptor->bits_per_sample;
  
              if (descriptor->sample_rate.den > 0) {
                  st->codecpar->sample_rate = descriptor->sample_rate.num / descriptor->sample_rate.den;
                  avpriv_set_pts_info(st, 64, descriptor->sample_rate.den, descriptor->sample_rate.num);
              } else {
                  av_log(mxf->fc, AV_LOG_WARNING, "invalid sample rate (%d/%d) "
                         "found for stream #%d, time base forced to 1/48000\n",
                         descriptor->sample_rate.num, descriptor->sample_rate.den,
                         st->index);
                  avpriv_set_pts_info(st, 64, 1, 48000);
              }
  
              /* if duration is set, rescale it from EditRate to SampleRate */
              if (st->duration != AV_NOPTS_VALUE)
                  st->duration = av_rescale_q(st->duration,
                                              av_inv_q(material_track->edit_rate),
                                              st->time_base);
  
              /* TODO: implement AV_CODEC_ID_RAWAUDIO */
              if (st->codecpar->codec_id == AV_CODEC_ID_PCM_S16LE) {
                  if (descriptor->bits_per_sample > 16 && descriptor->bits_per_sample <= 24)
                      st->codecpar->codec_id = AV_CODEC_ID_PCM_S24LE;
                  else if (descriptor->bits_per_sample == 32)
                      st->codecpar->codec_id = AV_CODEC_ID_PCM_S32LE;
              } else if (st->codecpar->codec_id == AV_CODEC_ID_PCM_S16BE) {
                  if (descriptor->bits_per_sample > 16 && descriptor->bits_per_sample <= 24)
                      st->codecpar->codec_id = AV_CODEC_ID_PCM_S24BE;
                  else if (descriptor->bits_per_sample == 32)
                      st->codecpar->codec_id = AV_CODEC_ID_PCM_S32BE;
              } else if (st->codecpar->codec_id == AV_CODEC_ID_MP2) {
                  st->need_parsing = AVSTREAM_PARSE_FULL;
              }
          } else if (st->codecpar->codec_type == AVMEDIA_TYPE_DATA) {
              int codec_id = mxf_get_codec_ul(mxf_data_essence_container_uls,
                                              essence_container_ul)->id;
              if (codec_id >= 0 &&
                  codec_id < FF_ARRAY_ELEMS(mxf_data_essence_descriptor)) {
                  av_dict_set(&st->metadata, "data_type",
                              mxf_data_essence_descriptor[codec_id], 0);
              }
          }
          if (descriptor->extradata) {
              st->codecpar->extradata = av_mallocz(descriptor->extradata_size + AV_INPUT_BUFFER_PADDING_SIZE);
              if (st->codecpar->extradata) {
                  memcpy(st->codecpar->extradata, descriptor->extradata, descriptor->extradata_size);
                  st->codecpar->extradata_size = descriptor->extradata_size;
              }
          } else if (st->codecpar->codec_id == AV_CODEC_ID_H264) {
              ret = ff_generate_avci_extradata(st);
              if (ret < 0)
                  return ret;
          }
          if (st->codecpar->codec_type != AVMEDIA_TYPE_DATA && (*essence_container_ul)[15] > 0x01) {
              /* TODO: decode timestamps */
              st->need_parsing = AVSTREAM_PARSE_TIMESTAMPS;
          }
      }
  
      ret = 0;
  fail_and_free:
      return ret;
  }
  
  static int mxf_read_utf16_string(AVIOContext *pb, int size, char** str)
  {
      int ret;
      size_t buf_size;
  
      if (size < 0)
          return AVERROR(EINVAL);
  
      buf_size = size + size / 2 + 1;
      *str = av_malloc(buf_size);
      if (!*str)
          return AVERROR(ENOMEM);
  
      if ((ret = avio_get_str16be(pb, size, *str, buf_size)) < 0) {
          av_freep(str);
          return ret;
      }
  
      return ret;
  }
  
  static int mxf_uid_to_str(UID uid, char **str)
  {
      int i;
      char *p;
      p = *str = av_mallocz(sizeof(UID) * 2 + 4 + 1);
      if (!p)
          return AVERROR(ENOMEM);
      for (i = 0; i < sizeof(UID); i++) {
          snprintf(p, 2 + 1, "%.2x", uid[i]);
          p += 2;
          if (i == 3 || i == 5 || i == 7 || i == 9) {
              snprintf(p, 1 + 1, "-");
              p++;
          }
      }
      return 0;
  }
  
  static int mxf_timestamp_to_str(uint64_t timestamp, char **str)
  {
      struct tm time = { 0 };
      time.tm_year = (timestamp >> 48) - 1900;
      time.tm_mon  = (timestamp >> 40 & 0xFF) - 1;
      time.tm_mday = (timestamp >> 32 & 0xFF);
      time.tm_hour = (timestamp >> 24 & 0xFF);
      time.tm_min  = (timestamp >> 16 & 0xFF);
      time.tm_sec  = (timestamp >> 8  & 0xFF);
  
      /* msvcrt versions of strftime calls the invalid parameter handler
       * (aborting the process if one isn't set) if the parameters are out
       * of range. */
      time.tm_mon  = av_clip(time.tm_mon,  0, 11);
      time.tm_mday = av_clip(time.tm_mday, 1, 31);
      time.tm_hour = av_clip(time.tm_hour, 0, 23);
      time.tm_min  = av_clip(time.tm_min,  0, 59);
      time.tm_sec  = av_clip(time.tm_sec,  0, 59);
  
      *str = av_mallocz(32);
      if (!*str)
          return AVERROR(ENOMEM);
      if (!strftime(*str, 32, "%Y-%m-%d %H:%M:%S", &time))
          (*str)[0] = '\0';
  
      return 0;
  }
  
  #define SET_STR_METADATA(pb, name, str) do { \
      if ((ret = mxf_read_utf16_string(pb, size, &str)) < 0) \
          return ret; \
      av_dict_set(&s->metadata, name, str, AV_DICT_DONT_STRDUP_VAL); \
  } while (0)
  
  #define SET_UID_METADATA(pb, name, var, str) do { \
      avio_read(pb, var, 16); \
      if ((ret = mxf_uid_to_str(var, &str)) < 0) \
          return ret; \
      av_dict_set(&s->metadata, name, str, AV_DICT_DONT_STRDUP_VAL); \
  } while (0)
  
  #define SET_TS_METADATA(pb, name, var, str) do { \
      var = avio_rb64(pb); \
      if ((ret = mxf_timestamp_to_str(var, &str)) < 0) \
          return ret; \
      av_dict_set(&s->metadata, name, str, AV_DICT_DONT_STRDUP_VAL); \
  } while (0)
  
  static int mxf_read_identification_metadata(void *arg, AVIOContext *pb, int tag, int size, UID _uid, int64_t klv_offset)
  {
      MXFContext *mxf = arg;
      AVFormatContext *s = mxf->fc;
      int ret;
      UID uid = { 0 };
      char *str = NULL;
      uint64_t ts;
      switch (tag) {
      case 0x3C01:
          SET_STR_METADATA(pb, "company_name", str);
          break;
      case 0x3C02:
          SET_STR_METADATA(pb, "product_name", str);
          break;
      case 0x3C04:
          SET_STR_METADATA(pb, "product_version", str);
          break;
      case 0x3C05:
          SET_UID_METADATA(pb, "product_uid", uid, str);
          break;
      case 0x3C06:
          SET_TS_METADATA(pb, "modification_date", ts, str);
          break;
      case 0x3C08:
          SET_STR_METADATA(pb, "application_platform", str);
          break;
      case 0x3C09:
          SET_UID_METADATA(pb, "generation_uid", uid, str);
          break;
      case 0x3C0A:
          SET_UID_METADATA(pb, "uid", uid, str);
          break;
      }
      return 0;
  }
  
  static const MXFMetadataReadTableEntry mxf_metadata_read_table[] = {
      { { 0x06,0x0e,0x2b,0x34,0x02,0x05,0x01,0x01,0x0d,0x01,0x02,0x01,0x01,0x05,0x01,0x00 }, mxf_read_primer_pack },
  //    { { 0x06,0x0e,0x2b,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x2f,0x00 }, mxf_read_preface_pack },
      { { 0x06,0x0e,0x2b,0x34,0x02,0x05,0x01,0x01,0x0d,0x01,0x02,0x01,0x01,0x02,0x01,0x00 }, mxf_read_partition_pack },
      { { 0x06,0x0e,0x2b,0x34,0x02,0x05,0x01,0x01,0x0d,0x01,0x02,0x01,0x01,0x02,0x02,0x00 }, mxf_read_partition_pack },
      { { 0x06,0x0e,0x2b,0x34,0x02,0x05,0x01,0x01,0x0d,0x01,0x02,0x01,0x01,0x02,0x03,0x00 }, mxf_read_partition_pack },
      { { 0x06,0x0e,0x2b,0x34,0x02,0x05,0x01,0x01,0x0d,0x01,0x02,0x01,0x01,0x02,0x04,0x00 }, mxf_read_partition_pack },
      { { 0x06,0x0e,0x2b,0x34,0x02,0x05,0x01,0x01,0x0d,0x01,0x02,0x01,0x01,0x03,0x01,0x00 }, mxf_read_partition_pack },
      { { 0x06,0x0e,0x2b,0x34,0x02,0x05,0x01,0x01,0x0d,0x01,0x02,0x01,0x01,0x03,0x02,0x00 }, mxf_read_partition_pack },
      { { 0x06,0x0e,0x2b,0x34,0x02,0x05,0x01,0x01,0x0d,0x01,0x02,0x01,0x01,0x03,0x03,0x00 }, mxf_read_partition_pack },
      { { 0x06,0x0e,0x2b,0x34,0x02,0x05,0x01,0x01,0x0d,0x01,0x02,0x01,0x01,0x03,0x04,0x00 }, mxf_read_partition_pack },
      { { 0x06,0x0e,0x2b,0x34,0x02,0x05,0x01,0x01,0x0d,0x01,0x02,0x01,0x01,0x04,0x02,0x00 }, mxf_read_partition_pack },
      { { 0x06,0x0e,0x2b,0x34,0x02,0x05,0x01,0x01,0x0d,0x01,0x02,0x01,0x01,0x04,0x04,0x00 }, mxf_read_partition_pack },
      { { 0x06,0x0e,0x2b,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x30,0x00 }, mxf_read_identification_metadata },
      { { 0x06,0x0e,0x2b,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x18,0x00 }, mxf_read_content_storage, 0, AnyType },
      { { 0x06,0x0e,0x2b,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x37,0x00 }, mxf_read_source_package, sizeof(MXFPackage), SourcePackage },
      { { 0x06,0x0e,0x2b,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x36,0x00 }, mxf_read_material_package, sizeof(MXFPackage), MaterialPackage },
      { { 0x06,0x0e,0x2b,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x0F,0x00 }, mxf_read_sequence, sizeof(MXFSequence), Sequence },
      { { 0x06,0x0e,0x2b,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x11,0x00 }, mxf_read_source_clip, sizeof(MXFStructuralComponent), SourceClip },
      { { 0x06,0x0e,0x2b,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x44,0x00 }, mxf_read_generic_descriptor, sizeof(MXFDescriptor), MultipleDescriptor },
      { { 0x06,0x0e,0x2b,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x42,0x00 }, mxf_read_generic_descriptor, sizeof(MXFDescriptor), Descriptor }, /* Generic Sound */
      { { 0x06,0x0e,0x2b,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x28,0x00 }, mxf_read_generic_descriptor, sizeof(MXFDescriptor), Descriptor }, /* CDCI */
      { { 0x06,0x0e,0x2b,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x29,0x00 }, mxf_read_generic_descriptor, sizeof(MXFDescriptor), Descriptor }, /* RGBA */
      { { 0x06,0x0e,0x2b,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x51,0x00 }, mxf_read_generic_descriptor, sizeof(MXFDescriptor), Descriptor }, /* MPEG 2 Video */
      { { 0x06,0x0e,0x2b,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x48,0x00 }, mxf_read_generic_descriptor, sizeof(MXFDescriptor), Descriptor }, /* Wave */
      { { 0x06,0x0e,0x2b,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x47,0x00 }, mxf_read_generic_descriptor, sizeof(MXFDescriptor), Descriptor }, /* AES3 */
      { { 0x06,0x0e,0x2b,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x51,0x00 }, mxf_read_generic_descriptor, sizeof(MXFDescriptor), Descriptor }, /* MPEG2VideoDescriptor */
      { { 0x06,0x0e,0x2b,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x5c,0x00 }, mxf_read_generic_descriptor, sizeof(MXFDescriptor), Descriptor }, /* VANC/VBI - SMPTE 436M */
      { { 0x06,0x0e,0x2b,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x5e,0x00 }, mxf_read_generic_descriptor, sizeof(MXFDescriptor), Descriptor }, /* MPEG2AudioDescriptor */
      { { 0x06,0x0e,0x2b,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x3A,0x00 }, mxf_read_track, sizeof(MXFTrack), Track }, /* Static Track */
      { { 0x06,0x0e,0x2b,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x3B,0x00 }, mxf_read_track, sizeof(MXFTrack), Track }, /* Generic Track */
      { { 0x06,0x0e,0x2b,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x04,0x01,0x02,0x02,0x00,0x00 }, mxf_read_cryptographic_context, sizeof(MXFCryptoContext), CryptoContext },
      { { 0x06,0x0e,0x2b,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x02,0x01,0x01,0x10,0x01,0x00 }, mxf_read_index_table_segment, sizeof(MXFIndexTableSegment), IndexTableSegment },
      { { 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 }, NULL, 0, AnyType },
  };
  
  static int mxf_read_local_tags(MXFContext *mxf, KLVPacket *klv, MXFMetadataReadFunc *read_child, int ctx_size, enum MXFMetadataSetType type)
  {
      AVIOContext *pb = mxf->fc->pb;
      MXFMetadataSet *ctx = ctx_size ? av_mallocz(ctx_size) : mxf;
      uint64_t klv_end = avio_tell(pb) + klv->length;
  
      if (!ctx)
          return AVERROR(ENOMEM);
      while (avio_tell(pb) + 4 < klv_end && !pb->eof_reached) {
          int ret;
          int tag = avio_rb16(pb);
          int size = avio_rb16(pb); /* KLV specified by 0x53 */
          uint64_t next = avio_tell(pb) + size;
          UID uid = {0};
  
          av_log(mxf->fc, AV_LOG_TRACE, "local tag %#04x size %d\n", tag, size);
          if (!size) { /* ignore empty tag, needed for some files with empty UMID tag */
              av_log(mxf->fc, AV_LOG_ERROR, "local tag %#04x with 0 size\n", tag);
              continue;
          }
          if (tag > 0x7FFF) { /* dynamic tag */
              int i;
              for (i = 0; i < mxf->local_tags_count; i++) {
                  int local_tag = AV_RB16(mxf->local_tags+i*18);
                  if (local_tag == tag) {
                      memcpy(uid, mxf->local_tags+i*18+2, 16);
                      av_log(mxf->fc, AV_LOG_TRACE, "local tag %#04x\n", local_tag);
                      PRINT_KEY(mxf->fc, "uid", uid);
                  }
              }
          }
          if (ctx_size && tag == 0x3C0A)
              avio_read(pb, ctx->uid, 16);
          else if ((ret = read_child(ctx, pb, tag, size, uid, -1)) < 0)
              return ret;
  
          /* Accept the 64k local set limit being exceeded (Avid). Don't accept
           * it extending past the end of the KLV though (zzuf5.mxf). */
          if (avio_tell(pb) > klv_end) {
              if (ctx_size)
                  av_free(ctx);
  
              av_log(mxf->fc, AV_LOG_ERROR,
                     "local tag %#04x extends past end of local set @ %#"PRIx64"\n",
                     tag, klv->offset);
              return AVERROR_INVALIDDATA;
          } else if (avio_tell(pb) <= next)   /* only seek forward, else this can loop for a long time */
              avio_seek(pb, next, SEEK_SET);
      }
      if (ctx_size) ctx->type = type;
      return ctx_size ? mxf_add_metadata_set(mxf, ctx) : 0;
  }
  
  /**
   * Seeks to the previous partition, if possible
   * @return <= 0 if we should stop parsing, > 0 if we should keep going
   */
  static int mxf_seek_to_previous_partition(MXFContext *mxf)
  {
      AVIOContext *pb = mxf->fc->pb;
  
      if (!mxf->current_partition ||
          mxf->run_in + mxf->current_partition->previous_partition <= mxf->last_forward_tell)
          return 0;   /* we've parsed all partitions */
  
      /* seek to previous partition */
      avio_seek(pb, mxf->run_in + mxf->current_partition->previous_partition, SEEK_SET);
      mxf->current_partition = NULL;
  
      av_log(mxf->fc, AV_LOG_TRACE, "seeking to previous partition\n");
  
      return 1;
  }
  
  /**
   * Called when essence is encountered
   * @return <= 0 if we should stop parsing, > 0 if we should keep going
   */
  static int mxf_parse_handle_essence(MXFContext *mxf)
  {
      AVIOContext *pb = mxf->fc->pb;
      int64_t ret;
  
      if (mxf->parsing_backward) {
          return mxf_seek_to_previous_partition(mxf);
      } else {
          uint64_t offset = mxf->footer_partition ? mxf->footer_partition
                                                  : mxf->last_partition;
  
          if (!offset) {
              av_log(mxf->fc, AV_LOG_TRACE, "no last partition\n");
              return 0;
          }
  
          av_log(mxf->fc, AV_LOG_TRACE, "seeking to last partition\n");
  
          /* remember where we were so we don't end up seeking further back than this */
          mxf->last_forward_tell = avio_tell(pb);
  
          if (!pb->seekable) {
              av_log(mxf->fc, AV_LOG_INFO, "file is not seekable - not parsing last partition\n");
              return -1;
          }
  
          /* seek to last partition and parse backward */
          if ((ret = avio_seek(pb, mxf->run_in + offset, SEEK_SET)) < 0) {
              av_log(mxf->fc, AV_LOG_ERROR,
                     "failed to seek to last partition @ 0x%" PRIx64
                     " (%"PRId64") - partial file?\n",
                     mxf->run_in + offset, ret);
              return ret;
          }
  
          mxf->current_partition = NULL;
          mxf->parsing_backward = 1;
      }
  
      return 1;
  }
  
  /**
   * Called when the next partition or EOF is encountered
   * @return <= 0 if we should stop parsing, > 0 if we should keep going
   */
  static int mxf_parse_handle_partition_or_eof(MXFContext *mxf)
  {
      return mxf->parsing_backward ? mxf_seek_to_previous_partition(mxf) : 1;
  }
  
  /**
   * Figure out the proper offset and length of the essence container
   * in each partition
   */
  static void mxf_compute_essence_containers(MXFContext *mxf)
  {
      int x;
  
      /* everything is already correct */
      if (mxf->op == OPAtom)
          return;
  
      for (x = 0; x < mxf->partitions_count; x++) {
          MXFPartition *p = &mxf->partitions[x];
  
          if (!p->body_sid)
              continue;       /* BodySID == 0 -> no essence */
  
          if (x >= mxf->partitions_count - 1)
              break;          /* last partition - can't compute length (and we don't need to) */
  
          /* essence container spans to the next partition */
          p->essence_length = mxf->partitions[x+1].this_partition - p->essence_offset;
  
          if (p->essence_length < 0) {
              /* next ThisPartition < essence_offset */
              p->essence_length = 0;
              av_log(mxf->fc, AV_LOG_ERROR,
                     "partition %i: bad ThisPartition = %"PRIX64"\n",
                     x+1, mxf->partitions[x+1].this_partition);
          }
      }
  }
  
  static int64_t round_to_kag(int64_t position, int kag_size)
  {
      /* TODO: account for run-in? the spec isn't clear whether KAG should account for it */
      /* NOTE: kag_size may be any integer between 1 - 2^10 */
      int64_t ret = (position / kag_size) * kag_size;
      return ret == position ? ret : ret + kag_size;
  }
  
  static inline void compute_partition_essence_offset(AVFormatContext *s,
                                                      MXFContext *mxf,
                                                      KLVPacket *klv)
  {
      MXFPartition *cur_part = mxf->current_partition;
      /* for OP1a we compute essence_offset
       * for OPAtom we point essence_offset after the KL
       *     (usually op1a_essence_offset + 20 or 25)
       * TODO: for OP1a we could eliminate this entire if statement, always
       *       stopping parsing at op1a_essence_offset
       *       for OPAtom we still need the actual essence_offset though
       *       (the KL's length can vary)
       */
      int64_t op1a_essence_offset =
          round_to_kag(cur_part->this_partition + cur_part->pack_length,
                       cur_part->kag_size) +
          round_to_kag(cur_part->header_byte_count, cur_part->kag_size) +
          round_to_kag(cur_part->index_byte_count, cur_part->kag_size);
  
      if (mxf->op == OPAtom) {
          /* point essence_offset to the actual data
           * OPAtom has all the essence in one big KLV
           */
          cur_part->essence_offset = avio_tell(s->pb);
          cur_part->essence_length = klv->length;
      } else {
          /* NOTE: op1a_essence_offset may be less than to klv.offset
           * (C0023S01.mxf)  */
          cur_part->essence_offset = op1a_essence_offset;
      }
  }
  
  static int is_pcm(enum AVCodecID codec_id)
  {
      /* we only care about "normal" PCM codecs until we get samples */
      return codec_id >= AV_CODEC_ID_PCM_S16LE && codec_id < AV_CODEC_ID_PCM_S24DAUD;
  }
  
  /**
   * Deal with the case where for some audio atoms EditUnitByteCount is
   * very small (2, 4..). In those cases we should read more than one
   * sample per call to mxf_read_packet().
   */
  static void mxf_handle_small_eubc(AVFormatContext *s)
  {
      MXFContext *mxf = s->priv_data;
  
      /* assuming non-OPAtom == frame wrapped
       * no sane writer would wrap 2 byte PCM packets with 20 byte headers.. */
      if (mxf->op != OPAtom)
          return;
  
      /* expect PCM with exactly one index table segment and a small (< 32) EUBC */
      if (s->nb_streams != 1                                     ||
          s->streams[0]->codecpar->codec_type != AVMEDIA_TYPE_AUDIO ||
          !is_pcm(s->streams[0]->codecpar->codec_id)                ||
          mxf->nb_index_tables != 1                              ||
          mxf->index_tables[0].nb_segments != 1                  ||
          mxf->index_tables[0].segments[0]->edit_unit_byte_count >= 32)
          return;
  
      /* arbitrarily default to 48 kHz PAL audio frame size */
      /* TODO: We could compute this from the ratio between the audio
       *       and video edit rates for 48 kHz NTSC we could use the
       *       1802-1802-1802-1802-1801 pattern. */
      mxf->edit_units_per_packet = 1920;
  }
  
  static void mxf_read_random_index_pack(AVFormatContext *s)
  {
      MXFContext *mxf = s->priv_data;
      uint32_t length;
      int64_t file_size;
      KLVPacket klv;
  
      if (!s->pb->seekable)
          return;
  
      file_size = avio_size(s->pb);
      avio_seek(s->pb, file_size - 4, SEEK_SET);
      length = avio_rb32(s->pb);
      if (length <= 32 || length >= FFMIN(file_size, INT_MAX))
          goto end;
      avio_seek(s->pb, file_size - length, SEEK_SET);
      if (klv_read_packet(&klv, s->pb) < 0 ||
          !IS_KLV_KEY(klv.key, mxf_random_index_pack_key) ||
          klv.length != length - 20)
          goto end;
  
      avio_skip(s->pb, klv.length - 12);
      mxf->last_partition = avio_rb64(s->pb);
  
  end:
      avio_seek(s->pb, mxf->run_in, SEEK_SET);
  }
  
  static int mxf_read_header(AVFormatContext *s)
  {
      MXFContext *mxf = s->priv_data;
      KLVPacket klv;
      int64_t essence_offset = 0;
      int ret;
  
      mxf->last_forward_tell = INT64_MAX;
      mxf->edit_units_per_packet = 1;
  
      if (!mxf_read_sync(s->pb, mxf_header_partition_pack_key, 14)) {
          av_log(s, AV_LOG_ERROR, "could not find header partition pack key\n");
          return AVERROR_INVALIDDATA;
      }
      avio_seek(s->pb, -14, SEEK_CUR);
      mxf->fc = s;
      mxf->run_in = avio_tell(s->pb);
  
      mxf_read_random_index_pack(s);
  
      while (!s->pb->eof_reached) {
  
          const MXFMetadataReadTableEntry *metadata;
  
          if (klv_read_packet(&klv, s->pb) < 0) {
              /* EOF - seek to previous partition or stop */
              if(mxf_parse_handle_partition_or_eof(mxf) <= 0)
                  break;
              else
                  continue;
          }
  
          PRINT_KEY(s, "read header", klv.key);
          av_log(s, AV_LOG_TRACE, "size %"PRIu64" offset %#"PRIx64"\n", klv.length, klv.offset);
          if (IS_KLV_KEY(klv.key, mxf_encrypted_triplet_key) ||
              IS_KLV_KEY(klv.key, mxf_essence_element_key) ||
              IS_KLV_KEY(klv.key, mxf_avid_essence_element_key) ||
              IS_KLV_KEY(klv.key, mxf_system_item_key)) {
  
              if (!mxf->current_partition) {
                  av_log(mxf->fc, AV_LOG_ERROR,
                         "found essence prior to first PartitionPack\n");
                  return AVERROR_INVALIDDATA;
              }
  
              if (!mxf->current_partition->essence_offset) {
                  compute_partition_essence_offset(s, mxf, &klv);
              }
  
              if (!essence_offset)
                  essence_offset = klv.offset;
  
              /* seek to footer, previous partition or stop */
              if (mxf_parse_handle_essence(mxf) <= 0)
                  break;
              continue;
          } else if (!memcmp(klv.key, mxf_header_partition_pack_key, 13) &&
                     klv.key[13] >= 2 && klv.key[13] <= 4 && mxf->current_partition) {
              /* next partition pack - keep going, seek to previous partition or stop */
              if(mxf_parse_handle_partition_or_eof(mxf) <= 0)
                  break;
              else if (mxf->parsing_backward)
                  continue;
              /* we're still parsing forward. proceed to parsing this partition pack */
          }
  
          for (metadata = mxf_metadata_read_table; metadata->read; metadata++) {
              if (IS_KLV_KEY(klv.key, metadata->key)) {
                  int res;
                  if (klv.key[5] == 0x53) {
                      res = mxf_read_local_tags(mxf, &klv, metadata->read, metadata->ctx_size, metadata->type);
                  } else {
                      uint64_t next = avio_tell(s->pb) + klv.length;
                      res = metadata->read(mxf, s->pb, 0, klv.length, klv.key, klv.offset);
  
                      /* only seek forward, else this can loop for a long time */
                      if (avio_tell(s->pb) > next) {
                          av_log(s, AV_LOG_ERROR, "read past end of KLV @ %#"PRIx64"\n",
                                 klv.offset);
                          return AVERROR_INVALIDDATA;
                      }
  
                      avio_seek(s->pb, next, SEEK_SET);
                  }
                  if (res < 0) {
                      av_log(s, AV_LOG_ERROR, "error reading header metadata\n");
                      return res;
                  }
                  break;
              } else {
                  av_log(s, AV_LOG_VERBOSE, "Dark key " PRIxUID "\n",
                         UID_ARG(klv.key));
              }
          }
          if (!metadata->read)
              avio_skip(s->pb, klv.length);
      }
      /* FIXME avoid seek */
      if (!essence_offset)  {
          av_log(s, AV_LOG_ERROR, "no essence\n");
          return AVERROR_INVALIDDATA;
      }
      avio_seek(s->pb, essence_offset, SEEK_SET);
  
      mxf_compute_essence_containers(mxf);
  
      /* we need to do this before computing the index tables
       * to be able to fill in zero IndexDurations with st->duration */
      if ((ret = mxf_parse_structural_metadata(mxf)) < 0)
          return ret;
  
      if ((ret = mxf_compute_index_tables(mxf)) < 0)
          return ret;
  
      if (mxf->nb_index_tables > 1) {
          /* TODO: look up which IndexSID to use via EssenceContainerData */
          av_log(mxf->fc, AV_LOG_INFO, "got %i index tables - only the first one (IndexSID %i) will be used\n",
                 mxf->nb_index_tables, mxf->index_tables[0].index_sid);
      } else if (mxf->nb_index_tables == 0 && mxf->op == OPAtom) {
          av_log(mxf->fc, AV_LOG_ERROR, "cannot demux OPAtom without an index\n");
          return AVERROR_INVALIDDATA;
      }
  
      mxf_handle_small_eubc(s);
  
      return 0;
  }
  
  /**
   * Sets mxf->current_edit_unit based on what offset we're currently at.
   * @return next_ofs if OK, <0 on error
   */
  static int64_t mxf_set_current_edit_unit(MXFContext *mxf, int64_t current_offset)
  {
      int64_t last_ofs = -1, next_ofs = -1;
      MXFIndexTable *t = &mxf->index_tables[0];
  
      /* this is called from the OP1a demuxing logic, which means there
       * may be no index tables */
      if (mxf->nb_index_tables <= 0)
          return -1;
  
      /* find mxf->current_edit_unit so that the next edit unit starts ahead
       * of current_offset */
      while (mxf->current_edit_unit >= 0) {
          if (mxf_edit_unit_absolute_offset(mxf, t, mxf->current_edit_unit + 1,
                                            NULL, &next_ofs, 0) < 0)
              return -1;
  
          if (next_ofs <= last_ofs) {
              /* large next_ofs didn't change or current_edit_unit wrapped
               * around this fixes the infinite loop on zzuf3.mxf */
              av_log(mxf->fc, AV_LOG_ERROR,
                     "next_ofs didn't change. not deriving packet timestamps\n");
              return -1;
          }
  
          if (next_ofs > current_offset)
              break;
  
          last_ofs = next_ofs;
          mxf->current_edit_unit++;
      }
  
      /* not checking mxf->current_edit_unit >= t->nb_ptses here since CBR files
       * may lack IndexEntryArrays */
      if (mxf->current_edit_unit < 0)
          return -1;
  
      return next_ofs;
  }
  
  static int mxf_compute_sample_count(MXFContext *mxf, int stream_index,
                                      uint64_t *sample_count)
  {
      int i, total = 0, size = 0;
      AVStream *st = mxf->fc->streams[stream_index];
      MXFTrack *track = st->priv_data;
      AVRational time_base = av_inv_q(track->edit_rate);
      AVRational sample_rate = av_inv_q(st->time_base);
      const MXFSamplesPerFrame *spf = NULL;
  
      if ((sample_rate.num / sample_rate.den) == 48000)
          spf = ff_mxf_get_samples_per_frame(mxf->fc, time_base);
      if (!spf) {
          int remainder = (sample_rate.num * time_base.num) %
                          (time_base.den * sample_rate.den);
          *sample_count = av_q2d(av_mul_q((AVRational){mxf->current_edit_unit, 1},
                                          av_mul_q(sample_rate, time_base)));
          if (remainder)
              av_log(mxf->fc, AV_LOG_WARNING,
                     "seeking detected on stream #%d with time base (%d/%d) and "
                     "sample rate (%d/%d), audio pts won't be accurate.\n",
                     stream_index, time_base.num, time_base.den,
                     sample_rate.num, sample_rate.den);
          return 0;
      }
  
      while (spf->samples_per_frame[size]) {
          total += spf->samples_per_frame[size];
          size++;
      }
  
      if (!size)
          return 0;
  
      *sample_count = (mxf->current_edit_unit / size) * (uint64_t)total;
      for (i = 0; i < mxf->current_edit_unit % size; i++) {
          *sample_count += spf->samples_per_frame[i];
      }
  
      return 0;
  }
  
  static int mxf_set_audio_pts(MXFContext *mxf, AVCodecParameters *par,
                               AVPacket *pkt)
  {
      MXFTrack *track = mxf->fc->streams[pkt->stream_index]->priv_data;
      int64_t bits_per_sample = par->bits_per_coded_sample;
  
      if (!bits_per_sample)
          bits_per_sample = av_get_bits_per_sample(par->codec_id);
  
      pkt->pts = track->sample_count;
  
      if (par->channels <= 0 || par->channels * bits_per_sample < 8)
          return AVERROR_INVALIDDATA;
  
      track->sample_count += pkt->size / (par->channels * bits_per_sample / 8);
      return 0;
  }
  
  static int mxf_read_packet_old(AVFormatContext *s, AVPacket *pkt)
  {
      KLVPacket klv;
      MXFContext *mxf = s->priv_data;
      int ret;
  
      while (!s->pb->eof_reached) {
          if ((ret = klv_read_packet(&klv, s->pb)) < 0)
              return ret;
          PRINT_KEY(s, "read packet", klv.key);
          av_log(s, AV_LOG_TRACE, "size %"PRIu64" offset %#"PRIx64"\n", klv.length, klv.offset);
          if (IS_KLV_KEY(klv.key, mxf_encrypted_triplet_key)) {
              ret = mxf_decrypt_triplet(s, pkt, &klv);
              if (ret < 0) {
                  av_log(s, AV_LOG_ERROR, "invalid encoded triplet\n");
                  return ret;
              }
              return 0;
          }
          if (IS_KLV_KEY(klv.key, mxf_essence_element_key) ||
              IS_KLV_KEY(klv.key, mxf_avid_essence_element_key)) {
              int index = mxf_get_stream_index(s, &klv);
              int64_t next_ofs, next_klv;
              AVStream *st;
              MXFTrack *track;
              AVCodecParameters *par;
  
              if (index < 0) {
                  av_log(s, AV_LOG_ERROR,
                         "error getting stream index %"PRIu32"\n",
                         AV_RB32(klv.key + 12));
                  goto skip;
              }
  
              st = s->streams[index];
              track = st->priv_data;
  
              if (s->streams[index]->discard == AVDISCARD_ALL)
                  goto skip;
  
              next_klv = avio_tell(s->pb) + klv.length;
              next_ofs = mxf_set_current_edit_unit(mxf, klv.offset);
  
              if (next_ofs >= 0 && next_klv > next_ofs) {
                  /* if this check is hit then it's possible OPAtom was treated
                   * as OP1a truncate the packet since it's probably very large
                   * (>2 GiB is common) */
                  avpriv_request_sample(s,
                                        "OPAtom misinterpreted as OP1a?"
                                        "KLV for edit unit %i extending into "
                                        "next edit unit",
                                        mxf->current_edit_unit);
                  klv.length = next_ofs - avio_tell(s->pb);
              }
  
              /* check for 8 channels AES3 element */
              if (klv.key[12] == 0x06 && klv.key[13] == 0x01 && klv.key[14] == 0x10) {
                  ret = mxf_get_d10_aes3_packet(s->pb, s->streams[index],
                                                pkt, klv.length);
                  if (ret < 0) {
                      av_log(s, AV_LOG_ERROR, "error reading D-10 aes3 frame\n");
                      return ret;
                  }
              } else {
                  ret = av_get_packet(s->pb, pkt, klv.length);
                  if (ret < 0)
                      return ret;
              }
              pkt->stream_index = index;
              pkt->pos = klv.offset;
  
              par = s->streams[index]->codecpar;
  
              if (par->codec_type == AVMEDIA_TYPE_VIDEO && next_ofs >= 0) {
                  /* mxf->current_edit_unit good - see if we have an
                   * index table to derive timestamps from */
                  MXFIndexTable *t = &mxf->index_tables[0];
  
                  if (mxf->nb_index_tables >= 1 &&
                      mxf->current_edit_unit < t->nb_ptses) {
                      pkt->dts = mxf->current_edit_unit + t->first_dts;
                      pkt->pts = t->ptses[mxf->current_edit_unit];
                  } else if (track->intra_only) {
                      /* intra-only -> PTS = EditUnit.
                       * let utils.c figure out DTS since it can be
                       * < PTS if low_delay = 0 (Sony IMX30) */
                      pkt->pts = mxf->current_edit_unit;
                  }
              } else if (par->codec_type == AVMEDIA_TYPE_AUDIO) {
                  ret = mxf_set_audio_pts(mxf, par, pkt);
                  if (ret < 0)
                      return ret;
              }
  
              /* seek for truncated packets */
              avio_seek(s->pb, next_klv, SEEK_SET);
  
              return 0;
          } else
          skip:
              avio_skip(s->pb, klv.length);
      }
      return AVERROR_EOF;
  }
  
  static int mxf_read_packet(AVFormatContext *s, AVPacket *pkt)
  {
      MXFContext *mxf = s->priv_data;
      int ret, size;
      int64_t ret64, pos, next_pos;
      AVStream *st;
      MXFIndexTable *t;
      int edit_units;
  
      if (mxf->op != OPAtom)
          return mxf_read_packet_old(s, pkt);
  
      /* OPAtom - clip wrapped demuxing */
      /* NOTE: mxf_read_header() makes sure nb_index_tables > 0 for OPAtom */
      st = s->streams[0];
      t = &mxf->index_tables[0];
  
      if (mxf->current_edit_unit >= st->duration)
          return AVERROR_EOF;
  
      edit_units = FFMIN(mxf->edit_units_per_packet, st->duration - mxf->current_edit_unit);
  
      if ((ret = mxf_edit_unit_absolute_offset(mxf, t, mxf->current_edit_unit, NULL, &pos, 1)) < 0)
          return ret;
  
      /* compute size by finding the next edit unit or the end of the essence container
       * not pretty, but it works */
      if ((ret = mxf_edit_unit_absolute_offset(mxf, t, mxf->current_edit_unit + edit_units, NULL, &next_pos, 0)) < 0 &&
          (next_pos = mxf_essence_container_end(mxf, t->body_sid)) <= 0) {
          av_log(s, AV_LOG_ERROR, "unable to compute the size of the last packet\n");
          return AVERROR_INVALIDDATA;
      }
  
      if ((size = next_pos - pos) <= 0) {
          av_log(s, AV_LOG_ERROR, "bad size: %i\n", size);
          return AVERROR_INVALIDDATA;
      }
  
      if ((ret64 = avio_seek(s->pb, pos, SEEK_SET)) < 0)
          return ret64;
  
      if ((ret = av_get_packet(s->pb, pkt, size)) != size)
          return ret < 0 ? ret : AVERROR_EOF;
  
      pkt->stream_index = 0;
  
      if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO && t->ptses &&
          mxf->current_edit_unit >= 0 && mxf->current_edit_unit < t->nb_ptses) {
          pkt->dts = mxf->current_edit_unit + t->first_dts;
          pkt->pts = t->ptses[mxf->current_edit_unit];
      } else if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
          int ret = mxf_set_audio_pts(mxf, st->codecpar, pkt);
          if (ret < 0)
              return ret;
      }
  
      mxf->current_edit_unit += edit_units;
  
      return 0;
  }
  
  
  static int mxf_read_close(AVFormatContext *s)
  {
      MXFContext *mxf = s->priv_data;
      MXFIndexTableSegment *seg;
      int i;
  
      av_freep(&mxf->packages_refs);
  
      for (i = 0; i < s->nb_streams; i++)
          s->streams[i]->priv_data = NULL;
  
      for (i = 0; i < mxf->metadata_sets_count; i++) {
          switch (mxf->metadata_sets[i]->type) {
          case Descriptor:
              av_freep(&((MXFDescriptor *)mxf->metadata_sets[i])->extradata);
              break;
          case MultipleDescriptor:
              av_freep(&((MXFDescriptor *)mxf->metadata_sets[i])->sub_descriptors_refs);
              break;
          case Sequence:
              av_freep(&((MXFSequence *)mxf->metadata_sets[i])->structural_components_refs);
              break;
          case SourcePackage:
          case MaterialPackage:
              av_freep(&((MXFPackage *)mxf->metadata_sets[i])->tracks_refs);
              break;
          case IndexTableSegment:
              seg = (MXFIndexTableSegment *)mxf->metadata_sets[i];
              av_freep(&seg->temporal_offset_entries);
              av_freep(&seg->flag_entries);
              av_freep(&seg->stream_offset_entries);
              break;
          default:
              break;
          }
          av_freep(&mxf->metadata_sets[i]);
      }
      av_freep(&mxf->partitions);
      av_freep(&mxf->metadata_sets);
      av_freep(&mxf->aesc);
      av_freep(&mxf->local_tags);
  
      for (i = 0; i < mxf->nb_index_tables; i++) {
          av_freep(&mxf->index_tables[i].segments);
          av_freep(&mxf->index_tables[i].ptses);
          av_freep(&mxf->index_tables[i].fake_index);
      }
      av_freep(&mxf->index_tables);
  
      return 0;
  }
  
  static int mxf_probe(AVProbeData *p) {
      uint8_t *bufp = p->buf;
      uint8_t *end = p->buf + p->buf_size;
  
      if (p->buf_size < sizeof(mxf_header_partition_pack_key))
          return 0;
  
      /* Must skip Run-In Sequence and search for MXF header partition pack key SMPTE 377M 5.5 */
      end -= sizeof(mxf_header_partition_pack_key);
      for (; bufp < end; bufp++) {
          if (IS_KLV_KEY(bufp, mxf_header_partition_pack_key))
              return AVPROBE_SCORE_MAX;
      }
      return 0;
  }
  
  /* rudimentary byte seek */
  /* XXX: use MXF Index */
  static int mxf_read_seek(AVFormatContext *s, int stream_index, int64_t sample_time, int flags)
  {
      AVStream *st = s->streams[stream_index];
      int64_t seconds;
      MXFContext* mxf = s->priv_data;
      int64_t seekpos;
      int i, ret;
      MXFIndexTable *t;
      MXFTrack *source_track = st->priv_data;
  
      /* if audio then truncate sample_time to EditRate */
      if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO)
          sample_time = av_rescale_q(sample_time, st->time_base,
                                     av_inv_q(source_track->edit_rate));
  
      if (mxf->nb_index_tables <= 0) {
      if (!s->bit_rate)
          return AVERROR_INVALIDDATA;
      if (sample_time < 0)
          sample_time = 0;
      seconds = av_rescale(sample_time, st->time_base.num, st->time_base.den);
  
      seekpos = avio_seek(s->pb, (s->bit_rate * seconds) >> 3, SEEK_SET);
      if (seekpos < 0)
          return seekpos;
  
      ff_update_cur_dts(s, st, sample_time);
      mxf->current_edit_unit = sample_time;
      } else {
          t = &mxf->index_tables[0];
  
          /* clamp above zero, else ff_index_search_timestamp() returns negative
           * this also means we allow seeking before the start */
          sample_time = FFMAX(sample_time, 0);
  
          if (t->fake_index) {
              /* behave as if we have a proper index */
              if ((sample_time = ff_index_search_timestamp(t->fake_index, t->nb_ptses, sample_time, flags)) < 0)
                  return sample_time;
          } else {
              /* no IndexEntryArray (one or more CBR segments)
               * make sure we don't seek past the end */
              sample_time = FFMIN(sample_time, source_track->original_duration - 1);
          }
  
          if ((ret = mxf_edit_unit_absolute_offset(mxf, t, sample_time, &sample_time, &seekpos, 1)) << 0)
              return ret;
  
          ff_update_cur_dts(s, st, sample_time);
          mxf->current_edit_unit = sample_time;
          avio_seek(s->pb, seekpos, SEEK_SET);
      }
  
      // Update all tracks sample count
      for (i = 0; i < s->nb_streams; i++) {
          AVStream *cur_st = s->streams[i];
          MXFTrack *cur_track = cur_st->priv_data;
          uint64_t current_sample_count = 0;
          if (cur_st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
              ret = mxf_compute_sample_count(mxf, i, &current_sample_count);
              if (ret < 0)
                  return ret;
  
              cur_track->sample_count = current_sample_count;
          }
      }
      return 0;
  }
  
  AVInputFormat ff_mxf_demuxer = {
      .name           = "mxf",
      .long_name      = NULL_IF_CONFIG_SMALL("MXF (Material eXchange Format)"),
      .priv_data_size = sizeof(MXFContext),
      .read_probe     = mxf_probe,
      .read_header    = mxf_read_header,
      .read_packet    = mxf_read_packet,
      .read_close     = mxf_read_close,
      .read_seek      = mxf_read_seek,
  };
  