text: /*
   * MPEG-2 transport stream (aka DVB) muxer
   * Copyright (c) 2003 Fabrice Bellard
   *
   * This file is part of FFmpeg.
   *
   * FFmpeg is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * FFmpeg is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with FFmpeg; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  #include "libavutil/avassert.h"
  #include "libavutil/bswap.h"
  #include "libavutil/crc.h"
  #include "libavutil/dict.h"
  #include "libavutil/intreadwrite.h"
  #include "libavutil/mathematics.h"
  #include "libavutil/opt.h"
  
  #include "libavcodec/ac3_parser_internal.h"
  #include "libavcodec/internal.h"
  
  #include "avformat.h"
  #include "avio_internal.h"
  #include "internal.h"
  #include "mpegts.h"
  
  #define PCR_TIME_BASE 27000000
  
  /* write DVB SI sections */
  
  #define DVB_PRIVATE_NETWORK_START 0xff01
  
  /*********************************************/
  /* mpegts section writer */
  
  typedef struct MpegTSSection {
      int pid;
      int cc;
      int discontinuity;
      void (*write_packet)(struct MpegTSSection *s, const uint8_t *packet);
      void *opaque;
  } MpegTSSection;
  
  typedef struct MpegTSService {
      MpegTSSection pmt; /* MPEG-2 PMT table context */
      int sid;           /* service ID */
      uint8_t name[256];
      uint8_t provider_name[256];
      int pcr_pid;
      AVProgram *program;
  } MpegTSService;
  
  // service_type values as defined in ETSI 300 468
  enum {
      MPEGTS_SERVICE_TYPE_DIGITAL_TV                   = 0x01,
      MPEGTS_SERVICE_TYPE_DIGITAL_RADIO                = 0x02,
      MPEGTS_SERVICE_TYPE_TELETEXT                     = 0x03,
      MPEGTS_SERVICE_TYPE_ADVANCED_CODEC_DIGITAL_RADIO = 0x0A,
      MPEGTS_SERVICE_TYPE_MPEG2_DIGITAL_HDTV           = 0x11,
      MPEGTS_SERVICE_TYPE_ADVANCED_CODEC_DIGITAL_SDTV  = 0x16,
      MPEGTS_SERVICE_TYPE_ADVANCED_CODEC_DIGITAL_HDTV  = 0x19,
      MPEGTS_SERVICE_TYPE_HEVC_DIGITAL_HDTV            = 0x1F,
  };
  typedef struct MpegTSWrite {
      const AVClass *av_class;
      MpegTSSection pat; /* MPEG-2 PAT table */
      MpegTSSection sdt; /* MPEG-2 SDT table context */
      MpegTSService **services;
      AVPacket *pkt;
      int64_t sdt_period; /* SDT period in PCR time base */
      int64_t pat_period; /* PAT/PMT period in PCR time base */
      int nb_services;
      int64_t first_pcr;
      int first_dts_checked;
      int64_t next_pcr;
      int mux_rate; ///< set to 1 when VBR
      int pes_payload_size;
      int64_t total_size;
  
      int transport_stream_id;
      int original_network_id;
      int service_id;
      int service_type;
  
      int pmt_start_pid;
      int start_pid;
      int m2ts_mode;
      int m2ts_video_pid;
      int m2ts_audio_pid;
      int m2ts_pgssub_pid;
      int m2ts_textsub_pid;
  
      int pcr_period_ms;
  #define MPEGTS_FLAG_REEMIT_PAT_PMT  0x01
  #define MPEGTS_FLAG_AAC_LATM        0x02
  #define MPEGTS_FLAG_PAT_PMT_AT_FRAMES           0x04
  #define MPEGTS_FLAG_SYSTEM_B        0x08
  #define MPEGTS_FLAG_DISCONT         0x10
      int flags;
      int copyts;
      int tables_version;
      int64_t pat_period_us;
      int64_t sdt_period_us;
      int64_t last_pat_ts;
      int64_t last_sdt_ts;
  
      int omit_video_pes_length;
  } MpegTSWrite;
  
  /* a PES packet header is generated every DEFAULT_PES_HEADER_FREQ packets */
  #define DEFAULT_PES_HEADER_FREQ  16
  #define DEFAULT_PES_PAYLOAD_SIZE ((DEFAULT_PES_HEADER_FREQ - 1) * 184 + 170)
  
  /* The section length is 12 bits. The first 2 are set to 0, the remaining
   * 10 bits should not exceed 1021. */
  #define SECTION_LENGTH 1020
  
  /* NOTE: 4 bytes must be left at the end for the crc32 */
  static void mpegts_write_section(MpegTSSection *s, uint8_t *buf, int len)
  {
      unsigned int crc;
      unsigned char packet[TS_PACKET_SIZE];
      const unsigned char *buf_ptr;
      unsigned char *q;
      int first, b, len1, left;
  
      crc = av_bswap32(av_crc(av_crc_get_table(AV_CRC_32_IEEE),
                              -1, buf, len - 4));
  
      buf[len - 4] = (crc >> 24) & 0xff;
      buf[len - 3] = (crc >> 16) & 0xff;
      buf[len - 2] = (crc >>  8) & 0xff;
      buf[len - 1] =  crc        & 0xff;
  
      /* send each packet */
      buf_ptr = buf;
      while (len > 0) {
          first = buf == buf_ptr;
          q     = packet;
          *q++  = 0x47;
          b     = s->pid >> 8;
          if (first)
              b |= 0x40;
          *q++  = b;
          *q++  = s->pid;
          s->cc = s->cc + 1 & 0xf;
          *q++  = 0x10 | s->cc;
          if (s->discontinuity) {
              q[-1] |= 0x20;
              *q++ = 1;
              *q++ = 0x80;
              s->discontinuity = 0;
          }
          if (first)
              *q++ = 0; /* 0 offset */
          len1 = TS_PACKET_SIZE - (q - packet);
          if (len1 > len)
              len1 = len;
          memcpy(q, buf_ptr, len1);
          q += len1;
          /* add known padding data */
          left = TS_PACKET_SIZE - (q - packet);
          if (left > 0)
              memset(q, 0xff, left);
  
          s->write_packet(s, packet);
  
          buf_ptr += len1;
          len     -= len1;
      }
  }
  
  static inline void put16(uint8_t **q_ptr, int val)
  {
      uint8_t *q;
      q      = *q_ptr;
      *q++   = val >> 8;
      *q++   = val;
      *q_ptr = q;
  }
  
  static int mpegts_write_section1(MpegTSSection *s, int tid, int id,
                                   int version, int sec_num, int last_sec_num,
                                   uint8_t *buf, int len)
  {
      uint8_t section[1024], *q;
      unsigned int tot_len;
      /* reserved_future_use field must be set to 1 for SDT */
      unsigned int flags = tid == SDT_TID ? 0xf000 : 0xb000;
  
      tot_len = 3 + 5 + len + 4;
      /* check if not too big */
      if (tot_len > 1024)
          return AVERROR_INVALIDDATA;
  
      q    = section;
      *q++ = tid;
      put16(&q, flags | (len + 5 + 4)); /* 5 byte header + 4 byte CRC */
      put16(&q, id);
      *q++ = 0xc1 | (version << 1); /* current_next_indicator = 1 */
      *q++ = sec_num;
      *q++ = last_sec_num;
      memcpy(q, buf, len);
  
      mpegts_write_section(s, section, tot_len);
      return 0;
  }
  
  /*********************************************/
  /* mpegts writer */
  
  #define DEFAULT_PROVIDER_NAME   "FFmpeg"
  #define DEFAULT_SERVICE_NAME    "Service"
  
  /* we retransmit the SI info at this rate */
  #define SDT_RETRANS_TIME 500
  #define PAT_RETRANS_TIME 100
  #define PCR_RETRANS_TIME 20
  
  typedef struct MpegTSWriteStream {
      int pid; /* stream associated pid */
      int cc;
      int discontinuity;
      int payload_size;
      int first_timestamp_checked; ///< first pts/dts check needed
      int prev_payload_key;
      int64_t payload_pts;
      int64_t payload_dts;
      int payload_flags;
      uint8_t *payload;
      AVFormatContext *amux;
      int data_st_warning;
  
      int64_t pcr_period; /* PCR period in PCR time base */
      int64_t last_pcr;
  
      /* For Opus */
      int opus_queued_samples;
      int opus_pending_trim_start;
  
      DVBAC3Descriptor *dvb_ac3_desc;
  } MpegTSWriteStream;
  
  static void mpegts_write_pat(AVFormatContext *s)
  {
      MpegTSWrite *ts = s->priv_data;
      MpegTSService *service;
      uint8_t data[SECTION_LENGTH], *q;
      int i;
  
      q = data;
      for (i = 0; i < ts->nb_services; i++) {
          service = ts->services[i];
          put16(&q, service->sid);
          put16(&q, 0xe000 | service->pmt.pid);
      }
      mpegts_write_section1(&ts->pat, PAT_TID, ts->transport_stream_id, ts->tables_version, 0, 0,
                            data, q - data);
  }
  
  static void putbuf(uint8_t **q_ptr, const uint8_t *buf, size_t len)
  {
      memcpy(*q_ptr, buf, len);
      *q_ptr += len;
  }
  
  static void put_registration_descriptor(uint8_t **q_ptr, uint32_t tag)
  {
      uint8_t *q = *q_ptr;
      *q++ = REGISTRATION_DESCRIPTOR;
      *q++ = 4;
      *q++ = tag;
      *q++ = tag >> 8;
      *q++ = tag >> 16;
      *q++ = tag >> 24;
      *q_ptr = q;
  }
  
  static int get_dvb_stream_type(AVFormatContext *s, AVStream *st)
  {
      MpegTSWrite *ts = s->priv_data;
      MpegTSWriteStream *ts_st = st->priv_data;
      int stream_type;
  
      switch (st->codecpar->codec_id) {
      case AV_CODEC_ID_MPEG1VIDEO:
      case AV_CODEC_ID_MPEG2VIDEO:
          stream_type = STREAM_TYPE_VIDEO_MPEG2;
          break;
      case AV_CODEC_ID_MPEG4:
          stream_type = STREAM_TYPE_VIDEO_MPEG4;
          break;
      case AV_CODEC_ID_H264:
          stream_type = STREAM_TYPE_VIDEO_H264;
          break;
      case AV_CODEC_ID_HEVC:
          stream_type = STREAM_TYPE_VIDEO_HEVC;
          break;
      case AV_CODEC_ID_CAVS:
          stream_type = STREAM_TYPE_VIDEO_CAVS;
          break;
      case AV_CODEC_ID_DIRAC:
          stream_type = STREAM_TYPE_VIDEO_DIRAC;
          break;
      case AV_CODEC_ID_VC1:
          stream_type = STREAM_TYPE_VIDEO_VC1;
          break;
      case AV_CODEC_ID_MP2:
      case AV_CODEC_ID_MP3:
          if (   st->codecpar->sample_rate > 0
              && st->codecpar->sample_rate < 32000) {
              stream_type = STREAM_TYPE_AUDIO_MPEG2;
          } else {
              stream_type = STREAM_TYPE_AUDIO_MPEG1;
          }
          break;
      case AV_CODEC_ID_AAC:
          stream_type = (ts->flags & MPEGTS_FLAG_AAC_LATM)
                        ? STREAM_TYPE_AUDIO_AAC_LATM
                        : STREAM_TYPE_AUDIO_AAC;
          break;
      case AV_CODEC_ID_AAC_LATM:
          stream_type = STREAM_TYPE_AUDIO_AAC_LATM;
          break;
      case AV_CODEC_ID_AC3:
          stream_type = (ts->flags & MPEGTS_FLAG_SYSTEM_B)
                        ? STREAM_TYPE_PRIVATE_DATA
                        : STREAM_TYPE_AUDIO_AC3;
          break;
      case AV_CODEC_ID_EAC3:
          stream_type = (ts->flags & MPEGTS_FLAG_SYSTEM_B)
                        ? STREAM_TYPE_PRIVATE_DATA
                        : STREAM_TYPE_AUDIO_EAC3;
          break;
      case AV_CODEC_ID_DTS:
          stream_type = STREAM_TYPE_AUDIO_DTS;
          break;
      case AV_CODEC_ID_TRUEHD:
          stream_type = STREAM_TYPE_AUDIO_TRUEHD;
          break;
      case AV_CODEC_ID_OPUS:
          stream_type = STREAM_TYPE_PRIVATE_DATA;
          break;
      case AV_CODEC_ID_TIMED_ID3:
          stream_type = STREAM_TYPE_METADATA;
          break;
      case AV_CODEC_ID_DVB_SUBTITLE:
      case AV_CODEC_ID_DVB_TELETEXT:
          stream_type = STREAM_TYPE_PRIVATE_DATA;
          break;
      case AV_CODEC_ID_SMPTE_KLV:
          if (st->codecpar->profile == FF_PROFILE_KLVA_SYNC) {
              stream_type = STREAM_TYPE_METADATA;
          } else {
              stream_type = STREAM_TYPE_PRIVATE_DATA;
          }
          break;
      default:
          av_log_once(s, AV_LOG_WARNING, AV_LOG_DEBUG, &ts_st->data_st_warning,
                      "Stream %d, codec %s, is muxed as a private data stream "
                      "and may not be recognized upon reading.\n", st->index,
                      avcodec_get_name(st->codecpar->codec_id));
          stream_type = STREAM_TYPE_PRIVATE_DATA;
          break;
      }
  
      return stream_type;
  }
  
  static int get_m2ts_stream_type(AVFormatContext *s, AVStream *st)
  {
      int stream_type;
      MpegTSWriteStream *ts_st = st->priv_data;
  
      switch (st->codecpar->codec_id) {
      case AV_CODEC_ID_MPEG2VIDEO:
          stream_type = STREAM_TYPE_VIDEO_MPEG2;
          break;
      case AV_CODEC_ID_H264:
          stream_type = STREAM_TYPE_VIDEO_H264;
          break;
      case AV_CODEC_ID_VC1:
          stream_type = STREAM_TYPE_VIDEO_VC1;
          break;
      case AV_CODEC_ID_HEVC:
          stream_type = STREAM_TYPE_VIDEO_HEVC;
          break;
      case AV_CODEC_ID_PCM_BLURAY:
          stream_type = 0x80;
          break;
      case AV_CODEC_ID_AC3:
          stream_type = 0x81;
          break;
      case AV_CODEC_ID_DTS:
          stream_type = (st->codecpar->channels > 6) ? 0x85 : 0x82;
          break;
      case AV_CODEC_ID_TRUEHD:
          stream_type = 0x83;
          break;
      case AV_CODEC_ID_EAC3:
          stream_type = 0x84;
          break;
      case AV_CODEC_ID_HDMV_PGS_SUBTITLE:
          stream_type = 0x90;
          break;
      case AV_CODEC_ID_HDMV_TEXT_SUBTITLE:
          stream_type = 0x92;
          break;
      default:
          av_log_once(s, AV_LOG_WARNING, AV_LOG_DEBUG, &ts_st->data_st_warning,
                      "Stream %d, codec %s, is muxed as a private data stream "
                      "and may not be recognized upon reading.\n", st->index,
                      avcodec_get_name(st->codecpar->codec_id));
          stream_type = STREAM_TYPE_PRIVATE_DATA;
          break;
      }
  
      return stream_type;
  }
  
  static int mpegts_write_pmt(AVFormatContext *s, MpegTSService *service)
  {
      MpegTSWrite *ts = s->priv_data;
      uint8_t data[SECTION_LENGTH], *q, *desc_length_ptr, *program_info_length_ptr;
      int val, stream_type, i, err = 0;
  
      q = data;
      put16(&q, 0xe000 | service->pcr_pid);
  
      program_info_length_ptr = q;
      q += 2; /* patched after */
  
      /* put program info here */
      if (ts->m2ts_mode) {
          put_registration_descriptor(&q, MKTAG('H', 'D', 'M', 'V'));
          *q++ = 0x88;        // descriptor_tag - hdmv_copy_control_descriptor
          *q++ = 0x04;        // descriptor_length
          put16(&q, 0x0fff);  // CA_System_ID
          *q++ = 0xfc;        // private_data_byte
          *q++ = 0xfc;        // private_data_byte
      }
  
      val = 0xf000 | (q - program_info_length_ptr - 2);
      program_info_length_ptr[0] = val >> 8;
      program_info_length_ptr[1] = val;
  
      for (i = 0; i < s->nb_streams; i++) {
          AVStream *st = s->streams[i];
          MpegTSWriteStream *ts_st = st->priv_data;
          AVDictionaryEntry *lang = av_dict_get(st->metadata, "language", NULL, 0);
          enum AVCodecID codec_id = st->codecpar->codec_id;
  
          if (s->nb_programs) {
              int k, found = 0;
              AVProgram *program = service->program;
  
              for (k = 0; k < program->nb_stream_indexes; k++)
                  if (program->stream_index[k] == i) {
                      found = 1;
                      break;
                  }
  
              if (!found)
                  continue;
          }
  
          if (q - data > SECTION_LENGTH - 32) {
              err = 1;
              break;
          }
  
          stream_type = ts->m2ts_mode ? get_m2ts_stream_type(s, st) : get_dvb_stream_type(s, st);
  
          *q++ = stream_type;
          put16(&q, 0xe000 | ts_st->pid);
          desc_length_ptr = q;
          q += 2; /* patched after */
  
          /* write optional descriptors here */
          switch (st->codecpar->codec_type) {
          case AVMEDIA_TYPE_AUDIO:
              if (codec_id == AV_CODEC_ID_AC3)
                  put_registration_descriptor(&q, MKTAG('A', 'C', '-', '3'));
              if (codec_id == AV_CODEC_ID_EAC3)
                  put_registration_descriptor(&q, MKTAG('E', 'A', 'C', '3'));
              if (ts->flags & MPEGTS_FLAG_SYSTEM_B) {
                  if (codec_id == AV_CODEC_ID_AC3) {
                      DVBAC3Descriptor *dvb_ac3_desc = ts_st->dvb_ac3_desc;
  
                      *q++=0x6a; // AC3 descriptor see A038 DVB SI
                      if (dvb_ac3_desc) {
                          int len = 1 +
                                    !!(dvb_ac3_desc->component_type_flag) +
                                    !!(dvb_ac3_desc->bsid_flag) +
                                    !!(dvb_ac3_desc->mainid_flag) +
                                    !!(dvb_ac3_desc->asvc_flag);
  
                          *q++ = len;
                          *q++ = dvb_ac3_desc->component_type_flag << 7 | dvb_ac3_desc->bsid_flag << 6 |
                                 dvb_ac3_desc->mainid_flag         << 5 | dvb_ac3_desc->asvc_flag << 4;
  
                          if (dvb_ac3_desc->component_type_flag) *q++ = dvb_ac3_desc->component_type;
                          if (dvb_ac3_desc->bsid_flag)           *q++ = dvb_ac3_desc->bsid;
                          if (dvb_ac3_desc->mainid_flag)         *q++ = dvb_ac3_desc->mainid;
                          if (dvb_ac3_desc->asvc_flag)           *q++ = dvb_ac3_desc->asvc;
                      } else {
                          *q++=1; // 1 byte, all flags sets to 0
                          *q++=0; // omit all fields...
                      }
                  } else if (codec_id == AV_CODEC_ID_EAC3) {
                      *q++=0x7a; // EAC3 descriptor see A038 DVB SI
                      *q++=1; // 1 byte, all flags sets to 0
                      *q++=0; // omit all fields...
                  }
              }
              if (codec_id == AV_CODEC_ID_S302M)
                  put_registration_descriptor(&q, MKTAG('B', 'S', 'S', 'D'));
              if (codec_id == AV_CODEC_ID_OPUS) {
                  /* 6 bytes registration descriptor, 4 bytes Opus audio descriptor */
                  if (q - data > SECTION_LENGTH - 6 - 4) {
                      err = 1;
                      break;
                  }
  
                  put_registration_descriptor(&q, MKTAG('O', 'p', 'u', 's'));
  
                  *q++ = 0x7f; /* DVB extension descriptor */
                  *q++ = 2;
                  *q++ = 0x80;
  
                  if (st->codecpar->extradata && st->codecpar->extradata_size >= 19) {
                      if (st->codecpar->extradata[18] == 0 && st->codecpar->channels <= 2) {
                          /* RTP mapping family */
                          *q++ = st->codecpar->channels;
                      } else if (st->codecpar->extradata[18] == 1 && st->codecpar->channels <= 8 &&
                                 st->codecpar->extradata_size >= 21 + st->codecpar->channels) {
                          static const uint8_t coupled_stream_counts[9] = {
                              1, 0, 1, 1, 2, 2, 2, 3, 3
                          };
                          static const uint8_t channel_map_a[8][8] = {
                              {0},
                              {0, 1},
                              {0, 2, 1},
                              {0, 1, 2, 3},
                              {0, 4, 1, 2, 3},
                              {0, 4, 1, 2, 3, 5},
                              {0, 4, 1, 2, 3, 5, 6},
                              {0, 6, 1, 2, 3, 4, 5, 7},
                          };
                          static const uint8_t channel_map_b[8][8] = {
                              {0},
                              {0, 1},
                              {0, 1, 2},
                              {0, 1, 2, 3},
                              {0, 1, 2, 3, 4},
                              {0, 1, 2, 3, 4, 5},
                              {0, 1, 2, 3, 4, 5, 6},
                              {0, 1, 2, 3, 4, 5, 6, 7},
                          };
                          /* Vorbis mapping family */
  
                          if (st->codecpar->extradata[19] == st->codecpar->channels - coupled_stream_counts[st->codecpar->channels] &&
                              st->codecpar->extradata[20] == coupled_stream_counts[st->codecpar->channels] &&
                              memcmp(&st->codecpar->extradata[21], channel_map_a[st->codecpar->channels-1], st->codecpar->channels) == 0) {
                              *q++ = st->codecpar->channels;
                          } else if (st->codecpar->channels >= 2 && st->codecpar->extradata[19] == st->codecpar->channels &&
                                     st->codecpar->extradata[20] == 0 &&
                                     memcmp(&st->codecpar->extradata[21], channel_map_b[st->codecpar->channels-1], st->codecpar->channels) == 0) {
                              *q++ = st->codecpar->channels | 0x80;
                          } else {
                              /* Unsupported, could write an extended descriptor here */
                              av_log(s, AV_LOG_ERROR, "Unsupported Opus Vorbis-style channel mapping");
                              *q++ = 0xff;
                          }
                      } else {
                          /* Unsupported */
                          av_log(s, AV_LOG_ERROR, "Unsupported Opus channel mapping for family %d", st->codecpar->extradata[18]);
                          *q++ = 0xff;
                      }
                  } else if (st->codecpar->channels <= 2) {
                      /* Assume RTP mapping family */
                      *q++ = st->codecpar->channels;
                  } else {
                      /* Unsupported */
                      av_log(s, AV_LOG_ERROR, "Unsupported Opus channel mapping");
                      *q++ = 0xff;
                  }
              }
  
              if (lang) {
                  char *p;
                  char *next = lang->value;
                  uint8_t *len_ptr;
  
                  *q++     = ISO_639_LANGUAGE_DESCRIPTOR;
                  len_ptr  = q++;
                  *len_ptr = 0;
  
                  for (p = lang->value; next && *len_ptr < 255 / 4 * 4; p = next + 1) {
                      if (q - data > SECTION_LENGTH - 4) {
                          err = 1;
                          break;
                      }
                      next = strchr(p, ',');
                      if (strlen(p) != 3 && (!next || next != p + 3))
                          continue; /* not a 3-letter code */
  
                      *q++ = *p++;
                      *q++ = *p++;
                      *q++ = *p++;
  
                      if (st->disposition & AV_DISPOSITION_CLEAN_EFFECTS)
                          *q++ = 0x01;
                      else if (st->disposition & AV_DISPOSITION_HEARING_IMPAIRED)
                          *q++ = 0x02;
                      else if (st->disposition & AV_DISPOSITION_VISUAL_IMPAIRED)
                          *q++ = 0x03;
                      else
                          *q++ = 0; /* undefined type */
  
                      *len_ptr += 4;
                  }
  
                  if (*len_ptr == 0)
                      q -= 2; /* no language codes were written */
              }
              break;
          case AVMEDIA_TYPE_SUBTITLE:
          {
             const char default_language[] = "und";
             const char *language = lang && strlen(lang->value) >= 3 ? lang->value : default_language;
  
             if (codec_id == AV_CODEC_ID_DVB_SUBTITLE) {
                 uint8_t *len_ptr;
                 int extradata_copied = 0;
  
                 *q++ = 0x59; /* subtitling_descriptor */
                 len_ptr = q++;
  
                 while (strlen(language) >= 3) {
                     if (sizeof(data) - (q - data) < 8) { /* 8 bytes per DVB subtitle substream data */
                         err = 1;
                         break;
                     }
                     *q++ = *language++;
                     *q++ = *language++;
                     *q++ = *language++;
                     /* Skip comma */
                     if (*language != '\0')
                         language++;
  
                     if (st->codecpar->extradata_size - extradata_copied >= 5) {
                         *q++ = st->codecpar->extradata[extradata_copied + 4]; /* subtitling_type */
                         memcpy(q, st->codecpar->extradata + extradata_copied, 4); /* composition_page_id and ancillary_page_id */
                         extradata_copied += 5;
                         q += 4;
                     } else {
                         /* subtitling_type:
                          * 0x10 - normal with no monitor aspect ratio criticality
                          * 0x20 - for the hard of hearing with no monitor aspect ratio criticality */
                         *q++ = (st->disposition & AV_DISPOSITION_HEARING_IMPAIRED) ? 0x20 : 0x10;
                         if ((st->codecpar->extradata_size == 4) && (extradata_copied == 0)) {
                             /* support of old 4-byte extradata format */
                             memcpy(q, st->codecpar->extradata, 4); /* composition_page_id and ancillary_page_id */
                             extradata_copied += 4;
                             q += 4;
                         } else {
                             put16(&q, 1); /* composition_page_id */
                             put16(&q, 1); /* ancillary_page_id */
                         }
                     }
                 }
  
                 *len_ptr = q - len_ptr - 1;
             } else if (codec_id == AV_CODEC_ID_DVB_TELETEXT) {
                 uint8_t *len_ptr = NULL;
                 int extradata_copied = 0;
  
                 /* The descriptor tag. teletext_descriptor */
                 *q++ = 0x56;
                 len_ptr = q++;
  
                 while (strlen(language) >= 3 && q - data < sizeof(data) - 6) {
                     *q++ = *language++;
                     *q++ = *language++;
                     *q++ = *language++;
                     /* Skip comma */
                     if (*language != '\0')
                         language++;
  
                     if (st->codecpar->extradata_size - 1 > extradata_copied) {
                         memcpy(q, st->codecpar->extradata + extradata_copied, 2);
                         extradata_copied += 2;
                         q += 2;
                     } else {
                         /* The Teletext descriptor:
                          * teletext_type: This 5-bit field indicates the type of Teletext page indicated. (0x01 Initial Teletext page)
                          * teletext_magazine_number: This is a 3-bit field which identifies the magazine number.
                          * teletext_page_number: This is an 8-bit field giving two 4-bit hex digits identifying the page number. */
                         *q++ = 0x08;
                         *q++ = 0x00;
                     }
                 }
  
                 *len_ptr = q - len_ptr - 1;
              }
          }
          break;
          case AVMEDIA_TYPE_VIDEO:
              if (stream_type == STREAM_TYPE_VIDEO_DIRAC) {
                  put_registration_descriptor(&q, MKTAG('d', 'r', 'a', 'c'));
              } else if (stream_type == STREAM_TYPE_VIDEO_VC1) {
                  put_registration_descriptor(&q, MKTAG('V', 'C', '-', '1'));
              } else if (stream_type == STREAM_TYPE_VIDEO_HEVC && s->strict_std_compliance <= FF_COMPLIANCE_NORMAL) {
                  put_registration_descriptor(&q, MKTAG('H', 'E', 'V', 'C'));
              }
              break;
          case AVMEDIA_TYPE_DATA:
              if (codec_id == AV_CODEC_ID_SMPTE_KLV) {
                  put_registration_descriptor(&q, MKTAG('K', 'L', 'V', 'A'));
              } else if (codec_id == AV_CODEC_ID_TIMED_ID3) {
                  const char *tag = "ID3 ";
                  *q++ = METADATA_DESCRIPTOR;
                  *q++ = 13;
                  put16(&q, 0xffff);    /* metadata application format */
                  putbuf(&q, tag, strlen(tag));
                  *q++ = 0xff;        /* metadata format */
                  putbuf(&q, tag, strlen(tag));
                  *q++ = 0;            /* metadata service ID */
                  *q++ = 0xF;          /* metadata_locator_record_flag|MPEG_carriage_flags|reserved */
              }
              break;
          }
  
          val = 0xf000 | (q - desc_length_ptr - 2);
          desc_length_ptr[0] = val >> 8;
          desc_length_ptr[1] = val;
      }
  
      if (err)
          av_log(s, AV_LOG_ERROR,
                 "The PMT section cannot fit stream %d and all following streams.\n"
                 "Try reducing the number of languages in the audio streams "
                 "or the total number of streams.\n", i);
  
      mpegts_write_section1(&service->pmt, PMT_TID, service->sid, ts->tables_version, 0, 0,
                            data, q - data);
      return 0;
  }
  
  static void mpegts_write_sdt(AVFormatContext *s)
  {
      MpegTSWrite *ts = s->priv_data;
      MpegTSService *service;
      uint8_t data[SECTION_LENGTH], *q, *desc_list_len_ptr, *desc_len_ptr;
      int i, running_status, free_ca_mode, val;
  
      q = data;
      put16(&q, ts->original_network_id);
      *q++ = 0xff;
      for (i = 0; i < ts->nb_services; i++) {
          service = ts->services[i];
          put16(&q, service->sid);
          *q++              = 0xfc | 0x00; /* currently no EIT info */
          desc_list_len_ptr = q;
          q                += 2;
          running_status    = 4; /* running */
          free_ca_mode      = 0;
  
          /* write only one descriptor for the service name and provider */
          *q++         = 0x48;
          desc_len_ptr = q;
          q++;
          *q++         = ts->service_type;
          putbuf(&q, service->provider_name, service->provider_name[0] + 1);
          putbuf(&q, service->name, service->name[0] + 1);
          desc_len_ptr[0] = q - desc_len_ptr - 1;
  
          /* fill descriptor length */
          val = (running_status << 13) | (free_ca_mode << 12) |
                (q - desc_list_len_ptr - 2);
          desc_list_len_ptr[0] = val >> 8;
          desc_list_len_ptr[1] = val;
      }
      mpegts_write_section1(&ts->sdt, SDT_TID, ts->transport_stream_id, ts->tables_version, 0, 0,
                            data, q - data);
  }
  
  /* This stores a string in buf with the correct encoding and also sets the
   * first byte as the length. !str is accepted for an empty string.
   * If the string is already encoded, invalid UTF-8 or has no multibyte sequence
   * then we keep it as is, otherwise we signal UTF-8 encoding. */
  static int encode_str8(uint8_t *buf, const char *str)
  {
      size_t str_len;
      if (!str)
          str = "";
      str_len = strlen(str);
      if (str[0] && (unsigned)str[0] >= 0x20) {   /* Make sure the string is not already encoded. */
          const uint8_t *q = str;
          int has_multibyte = 0;
          while (*q) {
              uint32_t code;
              GET_UTF8(code, *q++, goto invalid;) /* Is it valid UTF-8? */
              has_multibyte |= (code > 127);      /* Does it have multibyte UTF-8 chars in it? */
          }
          if (has_multibyte) {                    /* If we have multibyte chars and valid UTF-8, then encode as such! */
              if (str_len > 254)
                  return AVERROR(EINVAL);
              buf[0] = str_len + 1;
              buf[1] = 0x15;
              memcpy(&buf[2], str, str_len);
              return 0;
          }
      }
  invalid:
      /* Otherwise let's just encode the string as is! */
      if (str_len > 255)
          return AVERROR(EINVAL);
      buf[0] = str_len;
      memcpy(&buf[1], str, str_len);
      return 0;
  }
  
  static int64_t get_pcr(const MpegTSWrite *ts)
  {
      return av_rescale(ts->total_size + 11, 8 * PCR_TIME_BASE, ts->mux_rate) +
             ts->first_pcr;
  }
  
  static void write_packet(AVFormatContext *s, const uint8_t *packet)
  {
      MpegTSWrite *ts = s->priv_data;
      if (ts->m2ts_mode) {
          int64_t pcr = get_pcr(s->priv_data);
          uint32_t tp_extra_header = pcr % 0x3fffffff;
          tp_extra_header = AV_RB32(&tp_extra_header);
          avio_write(s->pb, (unsigned char *) &tp_extra_header,
                     sizeof(tp_extra_header));
      }
      avio_write(s->pb, packet, TS_PACKET_SIZE);
      ts->total_size += TS_PACKET_SIZE;
  }
  
  static void section_write_packet(MpegTSSection *s, const uint8_t *packet)
  {
      AVFormatContext *ctx = s->opaque;
      write_packet(ctx, packet);
  }
  
  static MpegTSService *mpegts_add_service(AVFormatContext *s, int sid,
                                           const AVDictionary *metadata,
                                           AVProgram *program)
  {
      MpegTSWrite *ts = s->priv_data;
      MpegTSService *service;
      AVDictionaryEntry *title, *provider;
      char default_service_name[32];
      const char *service_name;
      const char *provider_name;
  
      title = av_dict_get(metadata, "service_name", NULL, 0);
      if (!title)
          title = av_dict_get(metadata, "title", NULL, 0);
      snprintf(default_service_name, sizeof(default_service_name), "%s%02d", DEFAULT_SERVICE_NAME, ts->nb_services + 1);
      service_name  = title ? title->value : default_service_name;
      provider      = av_dict_get(metadata, "service_provider", NULL, 0);
      provider_name = provider ? provider->value : DEFAULT_PROVIDER_NAME;
  
      service = av_mallocz(sizeof(MpegTSService));
      if (!service)
          return NULL;
      service->pmt.pid       = ts->pmt_start_pid + ts->nb_services;
      service->sid           = sid;
      service->pcr_pid       = 0x1fff;
      if (encode_str8(service->provider_name, provider_name) < 0 ||
          encode_str8(service->name, service_name) < 0) {
          av_log(s, AV_LOG_ERROR, "Too long service or provider name\n");
          goto fail;
      }
      if (av_dynarray_add_nofree(&ts->services, &ts->nb_services, service) < 0)
          goto fail;
  
      service->pmt.write_packet = section_write_packet;
      service->pmt.opaque       = s;
      service->pmt.cc           = 15;
      service->pmt.discontinuity= ts->flags & MPEGTS_FLAG_DISCONT;
      service->program          = program;
  
      return service;
  fail:
      av_free(service);
      return NULL;
  }
  
  static void enable_pcr_generation_for_stream(AVFormatContext *s, AVStream *pcr_st)
  {
      MpegTSWrite *ts = s->priv_data;
      MpegTSWriteStream *ts_st = pcr_st->priv_data;
  
      if (ts->mux_rate > 1 || ts->pcr_period_ms >= 0) {
          int pcr_period_ms = ts->pcr_period_ms == -1 ? PCR_RETRANS_TIME : ts->pcr_period_ms;
          ts_st->pcr_period = av_rescale(pcr_period_ms, PCR_TIME_BASE, 1000);
      } else {
          /* By default, for VBR we select the highest multiple of frame duration which is less than 100 ms. */
          int64_t frame_period = 0;
          if (pcr_st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
              int frame_size = av_get_audio_frame_duration2(pcr_st->codecpar, 0);
              if (!frame_size) {
                 av_log(s, AV_LOG_WARNING, "frame size not set\n");
                 frame_size = 512;
              }
              frame_period = av_rescale_rnd(frame_size, PCR_TIME_BASE, pcr_st->codecpar->sample_rate, AV_ROUND_UP);
          } else if (pcr_st->avg_frame_rate.num) {
              frame_period = av_rescale_rnd(pcr_st->avg_frame_rate.den, PCR_TIME_BASE, pcr_st->avg_frame_rate.num, AV_ROUND_UP);
          }
          if (frame_period > 0 && frame_period <= PCR_TIME_BASE / 10)
              ts_st->pcr_period = frame_period * (PCR_TIME_BASE / 10 / frame_period);
          else
              ts_st->pcr_period = 1;
      }
  
      // output a PCR as soon as possible
      ts_st->last_pcr   = ts->first_pcr - ts_st->pcr_period;
  }
  
  static void select_pcr_streams(AVFormatContext *s)
  {
      MpegTSWrite *ts = s->priv_data;
  
      for (int i = 0; i < ts->nb_services; i++) {
          MpegTSService *service = ts->services[i];
          AVStream *pcr_st = NULL;
          AVProgram *program = service->program;
          int nb_streams = program ? program->nb_stream_indexes : s->nb_streams;
  
          for (int j = 0; j < nb_streams; j++) {
              AVStream *st = s->streams[program ? program->stream_index[j] : j];
              if (!pcr_st ||
                  pcr_st->codecpar->codec_type != AVMEDIA_TYPE_VIDEO && st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
              {
                  pcr_st = st;
              }
          }
  
          if (pcr_st) {
              MpegTSWriteStream *ts_st = pcr_st->priv_data;
              service->pcr_pid = ts_st->pid;
              enable_pcr_generation_for_stream(s, pcr_st);
              av_log(s, AV_LOG_VERBOSE, "service %i using PCR in pid=%i, pcr_period=%"PRId64"ms\n",
                  service->sid, service->pcr_pid, av_rescale(ts_st->pcr_period, 1000, PCR_TIME_BASE));
          }
      }
  }
  
  static int mpegts_init(AVFormatContext *s)
  {
      MpegTSWrite *ts = s->priv_data;
      int i, j;
      int ret;
  
      if (ts->m2ts_mode == -1) {
          if (av_match_ext(s->url, "m2ts")) {
              ts->m2ts_mode = 1;
          } else {
              ts->m2ts_mode = 0;
          }
      }
  
      ts->m2ts_video_pid   = M2TS_VIDEO_PID;
      ts->m2ts_audio_pid   = M2TS_AUDIO_START_PID;
      ts->m2ts_pgssub_pid  = M2TS_PGSSUB_START_PID;
      ts->m2ts_textsub_pid = M2TS_TEXTSUB_PID;
  
      if (ts->m2ts_mode) {
          ts->pmt_start_pid = M2TS_PMT_PID;
          if (s->nb_programs > 1) {
              av_log(s, AV_LOG_ERROR, "Only one program is allowed in m2ts mode!\n");
              return AVERROR(EINVAL);
          }
      }
  
      if (s->max_delay < 0) /* Not set by the caller */
          s->max_delay = 0;
  
      // round up to a whole number of TS packets
      ts->pes_payload_size = (ts->pes_payload_size + 14 + 183) / 184 * 184 - 14;
  
      if (!s->nb_programs) {
          /* allocate a single DVB service */
          if (!mpegts_add_service(s, ts->service_id, s->metadata, NULL))
              return AVERROR(ENOMEM);
      } else {
          for (i = 0; i < s->nb_programs; i++) {
              AVProgram *program = s->programs[i];
              if (!mpegts_add_service(s, program->id, program->metadata, program))
                  return AVERROR(ENOMEM);
          }
      }
  
      ts->pat.pid          = PAT_PID;
      /* Initialize at 15 so that it wraps and is equal to 0 for the
       * first packet we write. */
      ts->pat.cc           = 15;
      ts->pat.discontinuity= ts->flags & MPEGTS_FLAG_DISCONT;
      ts->pat.write_packet = section_write_packet;
      ts->pat.opaque       = s;
  
      ts->sdt.pid          = SDT_PID;
      ts->sdt.cc           = 15;
      ts->sdt.discontinuity= ts->flags & MPEGTS_FLAG_DISCONT;
      ts->sdt.write_packet = section_write_packet;
      ts->sdt.opaque       = s;
  
      ts->pkt = av_packet_alloc();
      if (!ts->pkt)
          return AVERROR(ENOMEM);
  
      /* assign pids to each stream */
      for (i = 0; i < s->nb_streams; i++) {
          AVStream *st = s->streams[i];
          MpegTSWriteStream *ts_st;
  
          ts_st = av_mallocz(sizeof(MpegTSWriteStream));
          if (!ts_st) {
              return AVERROR(ENOMEM);
          }
          st->priv_data = ts_st;
  
          avpriv_set_pts_info(st, 33, 1, 90000);
  
          ts_st->payload = av_mallocz(ts->pes_payload_size);
          if (!ts_st->payload) {
              return AVERROR(ENOMEM);
          }
  
          /* MPEG pid values < 16 are reserved. Applications which set st->id in
           * this range are assigned a calculated pid. */
          if (st->id < 16) {
              if (ts->m2ts_mode) {
                  switch (st->codecpar->codec_type) {
                  case AVMEDIA_TYPE_VIDEO:
                      ts_st->pid = ts->m2ts_video_pid++;
                      break;
                  case AVMEDIA_TYPE_AUDIO:
                      ts_st->pid = ts->m2ts_audio_pid++;
                      break;
                  case AVMEDIA_TYPE_SUBTITLE:
                      switch (st->codecpar->codec_id) {
                      case AV_CODEC_ID_HDMV_PGS_SUBTITLE:
                          ts_st->pid = ts->m2ts_pgssub_pid++;
                          break;
                      case AV_CODEC_ID_HDMV_TEXT_SUBTITLE:
                          ts_st->pid = ts->m2ts_textsub_pid++;
                          break;
                      }
                      break;
                  }
                  if (ts->m2ts_video_pid   > M2TS_VIDEO_PID + 1          ||
                      ts->m2ts_audio_pid   > M2TS_AUDIO_START_PID + 32   ||
                      ts->m2ts_pgssub_pid  > M2TS_PGSSUB_START_PID + 32  ||
                      ts->m2ts_textsub_pid > M2TS_TEXTSUB_PID + 1        ||
                      ts_st->pid < 16) {
                      av_log(s, AV_LOG_ERROR, "Cannot automatically assign PID for stream %d\n", st->index);
                      return AVERROR(EINVAL);
                  }
              } else {
                  ts_st->pid = ts->start_pid + i;
              }
          } else {
              ts_st->pid = st->id;
          }
          if (ts_st->pid >= 0x1FFF) {
              av_log(s, AV_LOG_ERROR,
                     "Invalid stream id %d, must be less than 8191\n", st->id);
              return AVERROR(EINVAL);
          }
          for (j = 0; j < ts->nb_services; j++) {
              if (ts->services[j]->pmt.pid > LAST_OTHER_PID) {
                  av_log(s, AV_LOG_ERROR,
                         "Invalid PMT PID %d, must be less than %d\n", ts->services[j]->pmt.pid, LAST_OTHER_PID + 1);
                  return AVERROR(EINVAL);
              }
              if (ts_st->pid == ts->services[j]->pmt.pid) {
                  av_log(s, AV_LOG_ERROR, "PID %d cannot be both elementary and PMT PID\n", ts_st->pid);
                  return AVERROR(EINVAL);
              }
          }
          for (j = 0; j < i; j++) {
              MpegTSWriteStream *ts_st_prev = s->streams[j]->priv_data;
              if (ts_st_prev->pid == ts_st->pid) {
                  av_log(s, AV_LOG_ERROR, "Duplicate stream id %d\n", ts_st->pid);
                  return AVERROR(EINVAL);
              }
          }
          ts_st->payload_pts     = AV_NOPTS_VALUE;
          ts_st->payload_dts     = AV_NOPTS_VALUE;
          ts_st->cc              = 15;
          ts_st->discontinuity   = ts->flags & MPEGTS_FLAG_DISCONT;
          if (st->codecpar->codec_id == AV_CODEC_ID_AAC &&
              st->codecpar->extradata_size > 0) {
              AVStream *ast;
              ts_st->amux = avformat_alloc_context();
              if (!ts_st->amux) {
                  return AVERROR(ENOMEM);
              }
              ts_st->amux->oformat =
                  av_guess_format((ts->flags & MPEGTS_FLAG_AAC_LATM) ? "latm" : "adts",
                                  NULL, NULL);
              if (!ts_st->amux->oformat) {
                  return AVERROR(EINVAL);
              }
              if (!(ast = avformat_new_stream(ts_st->amux, NULL))) {
                  return AVERROR(ENOMEM);
              }
              ret = avcodec_parameters_copy(ast->codecpar, st->codecpar);
              if (ret != 0)
                  return ret;
              ast->time_base = st->time_base;
              ret = avformat_write_header(ts_st->amux, NULL);
              if (ret < 0)
                  return ret;
          }
          if (st->codecpar->codec_id == AV_CODEC_ID_OPUS) {
              ts_st->opus_pending_trim_start = st->codecpar->initial_padding * 48000 / st->codecpar->sample_rate;
          }
      }
  
      if (ts->copyts < 1)
          ts->first_pcr = av_rescale(s->max_delay, PCR_TIME_BASE, AV_TIME_BASE);
  
      select_pcr_streams(s);
  
      ts->last_pat_ts = AV_NOPTS_VALUE;
      ts->last_sdt_ts = AV_NOPTS_VALUE;
      ts->pat_period = av_rescale(ts->pat_period_us, PCR_TIME_BASE, AV_TIME_BASE);
      ts->sdt_period = av_rescale(ts->sdt_period_us, PCR_TIME_BASE, AV_TIME_BASE);
  
      if (ts->mux_rate == 1)
          av_log(s, AV_LOG_VERBOSE, "muxrate VBR, ");
      else
          av_log(s, AV_LOG_VERBOSE, "muxrate %d, ", ts->mux_rate);
      av_log(s, AV_LOG_VERBOSE,
             "sdt every %"PRId64" ms, pat/pmt every %"PRId64" ms\n",
             av_rescale(ts->sdt_period, 1000, PCR_TIME_BASE),
             av_rescale(ts->pat_period, 1000, PCR_TIME_BASE));
  
      return 0;
  }
  
  /* send SDT, PAT and PMT tables regularly */
  static void retransmit_si_info(AVFormatContext *s, int force_pat, int force_sdt, int64_t pcr)
  {
      MpegTSWrite *ts = s->priv_data;
      int i;
  
      if ((pcr != AV_NOPTS_VALUE && ts->last_sdt_ts == AV_NOPTS_VALUE) ||
          (pcr != AV_NOPTS_VALUE && pcr - ts->last_sdt_ts >= ts->sdt_period) ||
          force_sdt
      ) {
          if (pcr != AV_NOPTS_VALUE)
              ts->last_sdt_ts = FFMAX(pcr, ts->last_sdt_ts);
          mpegts_write_sdt(s);
      }
      if ((pcr != AV_NOPTS_VALUE && ts->last_pat_ts == AV_NOPTS_VALUE) ||
          (pcr != AV_NOPTS_VALUE && pcr - ts->last_pat_ts >= ts->pat_period) ||
          force_pat) {
          if (pcr != AV_NOPTS_VALUE)
              ts->last_pat_ts = FFMAX(pcr, ts->last_pat_ts);
          mpegts_write_pat(s);
          for (i = 0; i < ts->nb_services; i++)
              mpegts_write_pmt(s, ts->services[i]);
      }
  }
  
  static int write_pcr_bits(uint8_t *buf, int64_t pcr)
  {
      int64_t pcr_low = pcr % 300, pcr_high = pcr / 300;
  
      *buf++ = pcr_high >> 25;
      *buf++ = pcr_high >> 17;
      *buf++ = pcr_high >>  9;
      *buf++ = pcr_high >>  1;
      *buf++ = pcr_high <<  7 | pcr_low >> 8 | 0x7e;
      *buf++ = pcr_low;
  
      return 6;
  }
  
  /* Write a single null transport stream packet */
  static void mpegts_insert_null_packet(AVFormatContext *s)
  {
      uint8_t *q;
      uint8_t buf[TS_PACKET_SIZE];
  
      q    = buf;
      *q++ = 0x47;
      *q++ = 0x00 | 0x1f;
      *q++ = 0xff;
      *q++ = 0x10;
      memset(q, 0x0FF, TS_PACKET_SIZE - (q - buf));
      write_packet(s, buf);
  }
  
  /* Write a single transport stream packet with a PCR and no payload */
  static void mpegts_insert_pcr_only(AVFormatContext *s, AVStream *st)
  {
      MpegTSWrite *ts = s->priv_data;
      MpegTSWriteStream *ts_st = st->priv_data;
      uint8_t *q;
      uint8_t buf[TS_PACKET_SIZE];
  
      q    = buf;
      *q++ = 0x47;
      *q++ = ts_st->pid >> 8;
      *q++ = ts_st->pid;
      *q++ = 0x20 | ts_st->cc;   /* Adaptation only */
      /* Continuity Count field does not increment (see 13818-1 section 2.4.3.3) */
      *q++ = TS_PACKET_SIZE - 5; /* Adaptation Field Length */
      *q++ = 0x10;               /* Adaptation flags: PCR present */
      if (ts_st->discontinuity) {
          q[-1] |= 0x80;
          ts_st->discontinuity = 0;
      }
  
      /* PCR coded into 6 bytes */
      q += write_pcr_bits(q, get_pcr(ts));
  
      /* stuffing bytes */
      memset(q, 0xFF, TS_PACKET_SIZE - (q - buf));
      write_packet(s, buf);
  }
  
  static void write_pts(uint8_t *q, int fourbits, int64_t pts)
  {
      int val;
  
      val  = fourbits << 4 | (((pts >> 30) & 0x07) << 1) | 1;
      *q++ = val;
      val  = (((pts >> 15) & 0x7fff) << 1) | 1;
      *q++ = val >> 8;
      *q++ = val;
      val  = (((pts) & 0x7fff) << 1) | 1;
      *q++ = val >> 8;
      *q++ = val;
  }
  
  /* Set an adaptation field flag in an MPEG-TS packet*/
  static void set_af_flag(uint8_t *pkt, int flag)
  {
      // expect at least one flag to set
      av_assert0(flag);
  
      if ((pkt[3] & 0x20) == 0) {
          // no AF yet, set adaptation field flag
          pkt[3] |= 0x20;
          // 1 byte length, no flags
          pkt[4] = 1;
          pkt[5] = 0;
      }
      pkt[5] |= flag;
  }
  
  /* Extend the adaptation field by size bytes */
  static void extend_af(uint8_t *pkt, int size)
  {
      // expect already existing adaptation field
      av_assert0(pkt[3] & 0x20);
      pkt[4] += size;
  }
  
  /* Get a pointer to MPEG-TS payload (right after TS packet header) */
  static uint8_t *get_ts_payload_start(uint8_t *pkt)
  {
      if (pkt[3] & 0x20)
          return pkt + 5 + pkt[4];
      else
          return pkt + 4;
  }
  
  /* Add a PES header to the front of the payload, and segment into an integer
   * number of TS packets. The final TS packet is padded using an oversized
   * adaptation header to exactly fill the last TS packet.
   * NOTE: 'payload' contains a complete PES payload. */
  static void mpegts_write_pes(AVFormatContext *s, AVStream *st,
                               const uint8_t *payload, int payload_size,
                               int64_t pts, int64_t dts, int key, int stream_id)
  {
      MpegTSWriteStream *ts_st = st->priv_data;
      MpegTSWrite *ts = s->priv_data;
      uint8_t buf[TS_PACKET_SIZE];
      uint8_t *q;
      int val, is_start, len, header_len, write_pcr, is_dvb_subtitle, is_dvb_teletext, flags;
      int afc_len, stuffing_len;
      int64_t delay = av_rescale(s->max_delay, 90000, AV_TIME_BASE);
      int force_pat = st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO && key && !ts_st->prev_payload_key;
      int force_sdt = 0;
  
      av_assert0(ts_st->payload != buf || st->codecpar->codec_type != AVMEDIA_TYPE_VIDEO);
      if (ts->flags & MPEGTS_FLAG_PAT_PMT_AT_FRAMES && st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
          force_pat = 1;
      }
  
      if (ts->flags & MPEGTS_FLAG_REEMIT_PAT_PMT) {
          force_pat = 1;
          force_sdt = 1;
          ts->flags &= ~MPEGTS_FLAG_REEMIT_PAT_PMT;
      }
  
      is_start = 1;
      while (payload_size > 0) {
          int64_t pcr = AV_NOPTS_VALUE;
          if (ts->mux_rate > 1)
              pcr = get_pcr(ts);
          else if (dts != AV_NOPTS_VALUE)
              pcr = (dts - delay) * 300;
  
          retransmit_si_info(s, force_pat, force_sdt, pcr);
          force_pat = 0;
          force_sdt = 0;
  
          write_pcr = 0;
          if (ts->mux_rate > 1) {
              /* Send PCR packets for all PCR streams if needed */
              pcr = get_pcr(ts);
              if (pcr >= ts->next_pcr) {
                  int64_t next_pcr = INT64_MAX;
                  for (int i = 0; i < s->nb_streams; i++) {
                      /* Make the current stream the last, because for that we
                       * can insert the pcr into the payload later */
                      int st2_index = i < st->index ? i : (i + 1 == s->nb_streams ? st->index : i + 1);
                      AVStream *st2 = s->streams[st2_index];
                      MpegTSWriteStream *ts_st2 = st2->priv_data;
                      if (ts_st2->pcr_period) {
                          if (pcr - ts_st2->last_pcr >= ts_st2->pcr_period) {
                              ts_st2->last_pcr = FFMAX(pcr - ts_st2->pcr_period, ts_st2->last_pcr + ts_st2->pcr_period);
                              if (st2 != st) {
                                  mpegts_insert_pcr_only(s, st2);
                                  pcr = get_pcr(ts);
                              } else {
                                  write_pcr = 1;
                              }
                          }
                          next_pcr = FFMIN(next_pcr, ts_st2->last_pcr + ts_st2->pcr_period);
                      }
                  }
                  ts->next_pcr = next_pcr;
              }
              if (dts != AV_NOPTS_VALUE && (dts - pcr / 300) > delay) {
                  /* pcr insert gets priority over null packet insert */
                  if (write_pcr)
                      mpegts_insert_pcr_only(s, st);
                  else
                      mpegts_insert_null_packet(s);
                  /* recalculate write_pcr and possibly retransmit si_info */
                  continue;
              }
          } else if (ts_st->pcr_period && pcr != AV_NOPTS_VALUE) {
              if (pcr - ts_st->last_pcr >= ts_st->pcr_period && is_start) {
                  ts_st->last_pcr = FFMAX(pcr - ts_st->pcr_period, ts_st->last_pcr + ts_st->pcr_period);
                  write_pcr = 1;
              }
          }
  
          /* prepare packet header */
          q    = buf;
          *q++ = 0x47;
          val  = ts_st->pid >> 8;
          if (ts->m2ts_mode && st->codecpar->codec_id == AV_CODEC_ID_AC3)
              val |= 0x20;
          if (is_start)
              val |= 0x40;
          *q++      = val;
          *q++      = ts_st->pid;
          ts_st->cc = ts_st->cc + 1 & 0xf;
          *q++      = 0x10 | ts_st->cc; // payload indicator + CC
          if (ts_st->discontinuity) {
              set_af_flag(buf, 0x80);
              q = get_ts_payload_start(buf);
              ts_st->discontinuity = 0;
          }
          if (key && is_start && pts != AV_NOPTS_VALUE) {
              // set Random Access for key frames
              if (ts_st->pcr_period)
                  write_pcr = 1;
              set_af_flag(buf, 0x40);
              q = get_ts_payload_start(buf);
          }
          if (write_pcr) {
              set_af_flag(buf, 0x10);
              q = get_ts_payload_start(buf);
              // add 11, pcr references the last byte of program clock reference base
              if (dts != AV_NOPTS_VALUE && dts < pcr / 300)
                  av_log(s, AV_LOG_WARNING, "dts < pcr, TS is invalid\n");
              extend_af(buf, write_pcr_bits(q, pcr));
              q = get_ts_payload_start(buf);
          }
          if (is_start) {
              int pes_extension = 0;
              int pes_header_stuffing_bytes = 0;
              /* write PES header */
              *q++ = 0x00;
              *q++ = 0x00;
              *q++ = 0x01;
              is_dvb_subtitle = 0;
              is_dvb_teletext = 0;
              if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
                  if (st->codecpar->codec_id == AV_CODEC_ID_DIRAC)
                      *q++ = STREAM_ID_EXTENDED_STREAM_ID;
                  else
                      *q++ = STREAM_ID_VIDEO_STREAM_0;
              } else if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO &&
                         (st->codecpar->codec_id == AV_CODEC_ID_MP2 ||
                          st->codecpar->codec_id == AV_CODEC_ID_MP3 ||
                          st->codecpar->codec_id == AV_CODEC_ID_AAC)) {
                  *q++ = STREAM_ID_AUDIO_STREAM_0;
              } else if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO &&
                          st->codecpar->codec_id == AV_CODEC_ID_AC3 &&
                          ts->m2ts_mode) {
                  *q++ = STREAM_ID_EXTENDED_STREAM_ID;
              } else if (st->codecpar->codec_type == AVMEDIA_TYPE_DATA &&
                         st->codecpar->codec_id == AV_CODEC_ID_TIMED_ID3) {
                  *q++ = STREAM_ID_PRIVATE_STREAM_1;
              } else if (st->codecpar->codec_type == AVMEDIA_TYPE_DATA) {
                  *q++ = stream_id != -1 ? stream_id : STREAM_ID_METADATA_STREAM;
  
                  if (stream_id == STREAM_ID_PRIVATE_STREAM_1) /* asynchronous KLV */
                      pts = dts = AV_NOPTS_VALUE;
              } else {
                  *q++ = STREAM_ID_PRIVATE_STREAM_1;
                  if (st->codecpar->codec_type == AVMEDIA_TYPE_SUBTITLE) {
                      if (st->codecpar->codec_id == AV_CODEC_ID_DVB_SUBTITLE) {
                          is_dvb_subtitle = 1;
                      } else if (st->codecpar->codec_id == AV_CODEC_ID_DVB_TELETEXT) {
                          is_dvb_teletext = 1;
                      }
                  }
              }
              header_len = 0;
              flags      = 0;
              if (pts != AV_NOPTS_VALUE) {
                  header_len += 5;
                  flags      |= 0x80;
              }
              if (dts != AV_NOPTS_VALUE && pts != AV_NOPTS_VALUE && dts != pts) {
                  header_len += 5;
                  flags      |= 0x40;
              }
              if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO &&
                  st->codecpar->codec_id == AV_CODEC_ID_DIRAC) {
                  /* set PES_extension_flag */
                  pes_extension = 1;
                  flags        |= 0x01;
  
                  /* One byte for PES2 extension flag +
                   * one byte for extension length +
                   * one byte for extension id */
                  header_len += 3;
              }
              /* for Blu-ray AC3 Audio the PES Extension flag should be as follow
               * otherwise it will not play sound on blu-ray
               */
              if (ts->m2ts_mode &&
                  st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO &&
                  st->codecpar->codec_id == AV_CODEC_ID_AC3) {
                  /* set PES_extension_flag */
                  pes_extension = 1;
                  flags |= 0x01;
                  header_len += 3;
              }
              if (is_dvb_teletext) {
                  pes_header_stuffing_bytes = 0x24 - header_len;
                  header_len = 0x24;
              }
              len = payload_size + header_len + 3;
              /* 3 extra bytes should be added to DVB subtitle payload: 0x20 0x00 at the beginning and trailing 0xff */
              if (is_dvb_subtitle) {
                  len += 3;
                  payload_size++;
              }
              if (len > 0xffff)
                  len = 0;
              if (ts->omit_video_pes_length && st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
                  len = 0;
              }
              *q++ = len >> 8;
              *q++ = len;
              val  = 0x80;
              /* data alignment indicator is required for subtitle and data streams */
              if (st->codecpar->codec_type == AVMEDIA_TYPE_SUBTITLE || st->codecpar->codec_type == AVMEDIA_TYPE_DATA)
                  val |= 0x04;
              *q++ = val;
              *q++ = flags;
              *q++ = header_len;
              if (pts != AV_NOPTS_VALUE) {
                  write_pts(q, flags >> 6, pts);
                  q += 5;
              }
              if (dts != AV_NOPTS_VALUE && pts != AV_NOPTS_VALUE && dts != pts) {
                  write_pts(q, 1, dts);
                  q += 5;
              }
              if (pes_extension && st->codecpar->codec_id == AV_CODEC_ID_DIRAC) {
                  flags = 0x01;  /* set PES_extension_flag_2 */
                  *q++  = flags;
                  *q++  = 0x80 | 0x01; /* marker bit + extension length */
                  /* Set the stream ID extension flag bit to 0 and
                   * write the extended stream ID. */
                  *q++ = 0x00 | 0x60;
              }
              /* For Blu-ray AC3 Audio Setting extended flags */
              if (ts->m2ts_mode &&
                  pes_extension &&
                  st->codecpar->codec_id == AV_CODEC_ID_AC3) {
                  flags = 0x01; /* set PES_extension_flag_2 */
                  *q++ = flags;
                  *q++ = 0x80 | 0x01; /* marker bit + extension length */
                  *q++ = 0x00 | 0x71; /* for AC3 Audio (specifically on blue-rays) */
              }
  
  
              if (is_dvb_subtitle) {
                  /* First two fields of DVB subtitles PES data:
                   * data_identifier: for DVB subtitle streams shall be coded with the value 0x20
                   * subtitle_stream_id: for DVB subtitle stream shall be identified by the value 0x00 */
                  *q++ = 0x20;
                  *q++ = 0x00;
              }
              if (is_dvb_teletext) {
                  memset(q, 0xff, pes_header_stuffing_bytes);
                  q += pes_header_stuffing_bytes;
              }
              is_start = 0;
          }
          /* header size */
          header_len = q - buf;
          /* data len */
          len = TS_PACKET_SIZE - header_len;
          if (len > payload_size)
              len = payload_size;
          stuffing_len = TS_PACKET_SIZE - header_len - len;
          if (stuffing_len > 0) {
              /* add stuffing with AFC */
              if (buf[3] & 0x20) {
                  /* stuffing already present: increase its size */
                  afc_len = buf[4] + 1;
                  memmove(buf + 4 + afc_len + stuffing_len,
                          buf + 4 + afc_len,
                          header_len - (4 + afc_len));
                  buf[4] += stuffing_len;
                  memset(buf + 4 + afc_len, 0xff, stuffing_len);
              } else {
                  /* add stuffing */
                  memmove(buf + 4 + stuffing_len, buf + 4, header_len - 4);
                  buf[3] |= 0x20;
                  buf[4]  = stuffing_len - 1;
                  if (stuffing_len >= 2) {
                      buf[5] = 0x00;
                      memset(buf + 6, 0xff, stuffing_len - 2);
                  }
              }
          }
  
          if (is_dvb_subtitle && payload_size == len) {
              memcpy(buf + TS_PACKET_SIZE - len, payload, len - 1);
              buf[TS_PACKET_SIZE - 1] = 0xff; /* end_of_PES_data_field_marker: an 8-bit field with fixed contents 0xff for DVB subtitle */
          } else {
              memcpy(buf + TS_PACKET_SIZE - len, payload, len);
          }
  
          payload      += len;
          payload_size -= len;
          write_packet(s, buf);
      }
      ts_st->prev_payload_key = key;
  }
  
  int ff_check_h264_startcode(AVFormatContext *s, const AVStream *st, const AVPacket *pkt)
  {
      if (pkt->size < 5 || AV_RB32(pkt->data) != 0x0000001 && AV_RB24(pkt->data) != 0x000001) {
          if (!st->nb_frames) {
              av_log(s, AV_LOG_ERROR, "H.264 bitstream malformed, "
                     "no startcode found, use the video bitstream filter 'h264_mp4toannexb' to fix it "
                     "('-bsf:v h264_mp4toannexb' option with ffmpeg)\n");
              return AVERROR_INVALIDDATA;
          }
          av_log(s, AV_LOG_WARNING, "H.264 bitstream error, startcode missing, size %d", pkt->size);
          if (pkt->size)
              av_log(s, AV_LOG_WARNING, " data %08"PRIX32, AV_RB32(pkt->data));
          av_log(s, AV_LOG_WARNING, "\n");
      }
      return 0;
  }
  
  static int check_hevc_startcode(AVFormatContext *s, const AVStream *st, const AVPacket *pkt)
  {
      if (pkt->size < 5 || AV_RB32(pkt->data) != 0x0000001 && AV_RB24(pkt->data) != 0x000001) {
          if (!st->nb_frames) {
              av_log(s, AV_LOG_ERROR, "HEVC bitstream malformed, no startcode found\n");
              return AVERROR_PATCHWELCOME;
          }
          av_log(s, AV_LOG_WARNING, "HEVC bitstream error, startcode missing, size %d", pkt->size);
          if (pkt->size)
              av_log(s, AV_LOG_WARNING, " data %08"PRIX32, AV_RB32(pkt->data));
          av_log(s, AV_LOG_WARNING, "\n");
      }
      return 0;
  }
  
  /* Based on GStreamer's gst-plugins-base/ext/ogg/gstoggstream.c
   * Released under the LGPL v2.1+, written by
   * Vincent Penquerc'h <vincent.penquerch@collabora.co.uk>
   */
  static int opus_get_packet_samples(AVFormatContext *s, AVPacket *pkt)
  {
      static const int durations[32] = {
        480, 960, 1920, 2880,       /* Silk NB */
        480, 960, 1920, 2880,       /* Silk MB */
        480, 960, 1920, 2880,       /* Silk WB */
        480, 960,                   /* Hybrid SWB */
        480, 960,                   /* Hybrid FB */
        120, 240, 480, 960,         /* CELT NB */
        120, 240, 480, 960,         /* CELT NB */
        120, 240, 480, 960,         /* CELT NB */
        120, 240, 480, 960,         /* CELT NB */
      };
      int toc, frame_duration, nframes, duration;
  
      if (pkt->size < 1)
          return 0;
  
      toc = pkt->data[0];
  
      frame_duration = durations[toc >> 3];
      switch (toc & 3) {
      case 0:
          nframes = 1;
          break;
      case 1:
          nframes = 2;
          break;
      case 2:
          nframes = 2;
          break;
      case 3:
          if (pkt->size < 2)
              return 0;
          nframes = pkt->data[1] & 63;
          break;
      }
  
      duration = nframes * frame_duration;
      if (duration > 5760) {
          av_log(s, AV_LOG_WARNING,
                 "Opus packet duration > 120 ms, invalid");
          return 0;
      }
  
      return duration;
  }
  
  static int mpegts_write_packet_internal(AVFormatContext *s, AVPacket *pkt)
  {
      AVStream *st = s->streams[pkt->stream_index];
      int size = pkt->size;
      uint8_t *buf = pkt->data;
      uint8_t *data = NULL;
      MpegTSWrite *ts = s->priv_data;
      MpegTSWriteStream *ts_st = st->priv_data;
      const int64_t delay = av_rescale(s->max_delay, 90000, AV_TIME_BASE) * 2;
      const int64_t max_audio_delay = av_rescale(s->max_delay, 90000, AV_TIME_BASE) / 2;
      int64_t dts = pkt->dts, pts = pkt->pts;
      int opus_samples = 0;
      buffer_size_t side_data_size;
      uint8_t *side_data = NULL;
      int stream_id = -1;
  
      side_data = av_packet_get_side_data(pkt,
                                          AV_PKT_DATA_MPEGTS_STREAM_ID,
                                          &side_data_size);
      if (side_data)
          stream_id = side_data[0];
  
      if (ts->copyts < 1) {
          if (!ts->first_dts_checked && dts != AV_NOPTS_VALUE) {
              ts->first_pcr += dts * 300;
              ts->first_dts_checked = 1;
          }
  
          if (pts != AV_NOPTS_VALUE)
              pts += delay;
          if (dts != AV_NOPTS_VALUE)
              dts += delay;
      }
  
      if (!ts_st->first_timestamp_checked && (pts == AV_NOPTS_VALUE || dts == AV_NOPTS_VALUE)) {
          av_log(s, AV_LOG_ERROR, "first pts and dts value must be set\n");
          return AVERROR_INVALIDDATA;
      }
      ts_st->first_timestamp_checked = 1;
  
      if (st->codecpar->codec_id == AV_CODEC_ID_H264) {
          const uint8_t *p = buf, *buf_end = p + size;
          uint32_t state = -1;
          int extradd = (pkt->flags & AV_PKT_FLAG_KEY) ? st->codecpar->extradata_size : 0;
          int ret = ff_check_h264_startcode(s, st, pkt);
          if (ret < 0)
              return ret;
  
          if (extradd && AV_RB24(st->codecpar->extradata) > 1)
              extradd = 0;
  
          do {
              p = avpriv_find_start_code(p, buf_end, &state);
              av_log(s, AV_LOG_TRACE, "nal %"PRId32"\n", state & 0x1f);
              if ((state & 0x1f) == 7)
                  extradd = 0;
          } while (p < buf_end && (state & 0x1f) != 9 &&
                   (state & 0x1f) != 5 && (state & 0x1f) != 1);
  
          if ((state & 0x1f) != 5)
              extradd = 0;
          if ((state & 0x1f) != 9) { // AUD NAL
              data = av_malloc(pkt->size + 6 + extradd);
              if (!data)
                  return AVERROR(ENOMEM);
              memcpy(data + 6, st->codecpar->extradata, extradd);
              memcpy(data + 6 + extradd, pkt->data, pkt->size);
              AV_WB32(data, 0x00000001);
              data[4] = 0x09;
              data[5] = 0xf0; // any slice type (0xe) + rbsp stop one bit
              buf     = data;
              size    = pkt->size + 6 + extradd;
          }
      } else if (st->codecpar->codec_id == AV_CODEC_ID_AAC) {
          if (pkt->size < 2) {
              av_log(s, AV_LOG_ERROR, "AAC packet too short\n");
              return AVERROR_INVALIDDATA;
          }
          if ((AV_RB16(pkt->data) & 0xfff0) != 0xfff0) {
              int ret;
              AVPacket *pkt2 = ts->pkt;
  
              if (!ts_st->amux) {
                  av_log(s, AV_LOG_ERROR, "AAC bitstream not in ADTS format "
                                          "and extradata missing\n");
              } else {
                  av_packet_unref(pkt2);
                  pkt2->data = pkt->data;
                  pkt2->size = pkt->size;
                  av_assert0(pkt->dts != AV_NOPTS_VALUE);
                  pkt2->dts = av_rescale_q(pkt->dts, st->time_base, ts_st->amux->streams[0]->time_base);
  
                  ret = avio_open_dyn_buf(&ts_st->amux->pb);
                  if (ret < 0)
                      return ret;
  
                  ret = av_write_frame(ts_st->amux, pkt2);
                  if (ret < 0) {
                      ffio_free_dyn_buf(&ts_st->amux->pb);
                      return ret;
                  }
                  size            = avio_close_dyn_buf(ts_st->amux->pb, &data);
                  ts_st->amux->pb = NULL;
                  buf             = data;
              }
          }
      } else if (st->codecpar->codec_id == AV_CODEC_ID_HEVC) {
          const uint8_t *p = buf, *buf_end = p + size;
          uint32_t state = -1;
          int extradd = (pkt->flags & AV_PKT_FLAG_KEY) ? st->codecpar->extradata_size : 0;
          int ret = check_hevc_startcode(s, st, pkt);
          if (ret < 0)
              return ret;
  
          if (extradd && AV_RB24(st->codecpar->extradata) > 1)
              extradd = 0;
  
          do {
              p = avpriv_find_start_code(p, buf_end, &state);
              av_log(s, AV_LOG_TRACE, "nal %"PRId32"\n", (state & 0x7e)>>1);
              if ((state & 0x7e) == 2*32)
                  extradd = 0;
          } while (p < buf_end && (state & 0x7e) != 2*35 &&
                   (state & 0x7e) >= 2*32);
  
          if ((state & 0x7e) < 2*16 || (state & 0x7e) >= 2*24)
              extradd = 0;
          if ((state & 0x7e) != 2*35) { // AUD NAL
              data = av_malloc(pkt->size + 7 + extradd);
              if (!data)
                  return AVERROR(ENOMEM);
              memcpy(data + 7, st->codecpar->extradata, extradd);
              memcpy(data + 7 + extradd, pkt->data, pkt->size);
              AV_WB32(data, 0x00000001);
              data[4] = 2*35;
              data[5] = 1;
              data[6] = 0x50; // any slice type (0x4) + rbsp stop one bit
              buf     = data;
              size    = pkt->size + 7 + extradd;
          }
      } else if (st->codecpar->codec_id == AV_CODEC_ID_OPUS) {
          if (pkt->size < 2) {
              av_log(s, AV_LOG_ERROR, "Opus packet too short\n");
              return AVERROR_INVALIDDATA;
          }
  
          /* Add Opus control header */
          if ((AV_RB16(pkt->data) >> 5) != 0x3ff) {
              uint8_t *side_data;
              buffer_size_t side_data_size;
              int i, n;
              int ctrl_header_size;
              int trim_start = 0, trim_end = 0;
  
              opus_samples = opus_get_packet_samples(s, pkt);
  
              side_data = av_packet_get_side_data(pkt,
                                                  AV_PKT_DATA_SKIP_SAMPLES,
                                                  &side_data_size);
  
              if (side_data && side_data_size >= 10) {
                  trim_end = AV_RL32(side_data + 4) * 48000 / st->codecpar->sample_rate;
              }
  
              ctrl_header_size = pkt->size + 2 + pkt->size / 255 + 1;
              if (ts_st->opus_pending_trim_start)
                ctrl_header_size += 2;
              if (trim_end)
                ctrl_header_size += 2;
  
              data = av_malloc(ctrl_header_size);
              if (!data)
                  return AVERROR(ENOMEM);
  
              data[0] = 0x7f;
              data[1] = 0xe0;
              if (ts_st->opus_pending_trim_start)
                  data[1] |= 0x10;
              if (trim_end)
                  data[1] |= 0x08;
  
              n = pkt->size;
              i = 2;
              do {
                  data[i] = FFMIN(n, 255);
                  n -= 255;
                  i++;
              } while (n >= 0);
  
              av_assert0(2 + pkt->size / 255 + 1 == i);
  
              if (ts_st->opus_pending_trim_start) {
                  trim_start = FFMIN(ts_st->opus_pending_trim_start, opus_samples);
                  AV_WB16(data + i, trim_start);
                  i += 2;
                  ts_st->opus_pending_trim_start -= trim_start;
              }
              if (trim_end) {
                  trim_end = FFMIN(trim_end, opus_samples - trim_start);
                  AV_WB16(data + i, trim_end);
                  i += 2;
              }
  
              memcpy(data + i, pkt->data, pkt->size);
              buf     = data;
              size    = ctrl_header_size;
          } else {
              /* TODO: Can we get TS formatted data here? If so we will
               * need to count the samples of that too! */
              av_log(s, AV_LOG_WARNING, "Got MPEG-TS formatted Opus data, unhandled");
          }
      } else if (st->codecpar->codec_id == AV_CODEC_ID_AC3 && !ts_st->dvb_ac3_desc) {
          AC3HeaderInfo *hdr = NULL;
  
          if (avpriv_ac3_parse_header(&hdr, pkt->data, pkt->size) >= 0) {
              uint8_t number_of_channels_flag;
              uint8_t service_type_flag;
              uint8_t full_service_flag = 1;
              DVBAC3Descriptor *dvb_ac3_desc;
  
              dvb_ac3_desc = av_mallocz(sizeof(*dvb_ac3_desc));
              if (!dvb_ac3_desc) {
                  av_free(hdr);
                  return AVERROR(ENOMEM);
              }
  
              service_type_flag = hdr->bitstream_mode;
              switch (hdr->channel_mode) {
                  case AC3_CHMODE_DUALMONO:
                      number_of_channels_flag = 1;
                      break;
                  case AC3_CHMODE_MONO:
                      number_of_channels_flag = 0;
                      break;
                  case AC3_CHMODE_STEREO:
                      if (hdr->dolby_surround_mode == AC3_DSURMOD_ON)
                          number_of_channels_flag = 3;
                      else
                          number_of_channels_flag = 2;
                      break;
                  case AC3_CHMODE_3F:
                  case AC3_CHMODE_2F1R:
                  case AC3_CHMODE_3F1R:
                  case AC3_CHMODE_2F2R:
                  case AC3_CHMODE_3F2R:
                      number_of_channels_flag = 4;
                      break;
                  default: /* reserved */
                      number_of_channels_flag = 7;
                      break;
              }
  
              if (service_type_flag  == 1 || service_type_flag == 4 ||
                  (service_type_flag == 7 && !number_of_channels_flag))
                  full_service_flag = 0;
  
              dvb_ac3_desc->component_type_flag = 1;
              dvb_ac3_desc->component_type = (full_service_flag << 6)              |
                                             ((service_type_flag      & 0x7) << 3) |
                                             (number_of_channels_flag & 0x7);
              dvb_ac3_desc->bsid_flag   = 1;
              dvb_ac3_desc->bsid        = hdr->bitstream_id;
              dvb_ac3_desc->mainid_flag = 0;
              dvb_ac3_desc->asvc_flag   = 0;
  
              ts_st->dvb_ac3_desc = dvb_ac3_desc;
          }
          av_free(hdr);
      }
  
      if (ts_st->payload_size && (ts_st->payload_size + size > ts->pes_payload_size ||
          (dts != AV_NOPTS_VALUE && ts_st->payload_dts != AV_NOPTS_VALUE &&
           dts - ts_st->payload_dts >= max_audio_delay) ||
          ts_st->opus_queued_samples + opus_samples >= 5760 /* 120ms */)) {
          mpegts_write_pes(s, st, ts_st->payload, ts_st->payload_size,
                           ts_st->payload_pts, ts_st->payload_dts,
                           ts_st->payload_flags & AV_PKT_FLAG_KEY, stream_id);
          ts_st->payload_size = 0;
          ts_st->opus_queued_samples = 0;
      }
  
      if (st->codecpar->codec_type != AVMEDIA_TYPE_AUDIO || size > ts->pes_payload_size) {
          av_assert0(!ts_st->payload_size);
          // for video and subtitle, write a single pes packet
          mpegts_write_pes(s, st, buf, size, pts, dts,
                           pkt->flags & AV_PKT_FLAG_KEY, stream_id);
          ts_st->opus_queued_samples = 0;
          av_free(data);
          return 0;
      }
  
      if (!ts_st->payload_size) {
          ts_st->payload_pts   = pts;
          ts_st->payload_dts   = dts;
          ts_st->payload_flags = pkt->flags;
      }
  
      memcpy(ts_st->payload + ts_st->payload_size, buf, size);
      ts_st->payload_size += size;
      ts_st->opus_queued_samples += opus_samples;
  
      av_free(data);
  
      return 0;
  }
  
  static void mpegts_write_flush(AVFormatContext *s)
  {
      MpegTSWrite *ts = s->priv_data;
      int i;
  
      /* flush current packets */
      for (i = 0; i < s->nb_streams; i++) {
          AVStream *st = s->streams[i];
          MpegTSWriteStream *ts_st = st->priv_data;
          if (ts_st->payload_size > 0) {
              mpegts_write_pes(s, st, ts_st->payload, ts_st->payload_size,
                               ts_st->payload_pts, ts_st->payload_dts,
                               ts_st->payload_flags & AV_PKT_FLAG_KEY, -1);
              ts_st->payload_size = 0;
              ts_st->opus_queued_samples = 0;
          }
      }
  
      if (ts->m2ts_mode) {
          int packets = (avio_tell(s->pb) / (TS_PACKET_SIZE + 4)) % 32;
          while (packets++ < 32)
              mpegts_insert_null_packet(s);
      }
  }
  
  static int mpegts_write_packet(AVFormatContext *s, AVPacket *pkt)
  {
      if (!pkt) {
          mpegts_write_flush(s);
          return 1;
      } else {
          return mpegts_write_packet_internal(s, pkt);
      }
  }
  
  static int mpegts_write_end(AVFormatContext *s)
  {
      if (s->pb)
          mpegts_write_flush(s);
  
      return 0;
  }
  
  static void mpegts_deinit(AVFormatContext *s)
  {
      MpegTSWrite *ts = s->priv_data;
      MpegTSService *service;
      int i;
  
      av_packet_free(&ts->pkt);
  
      for (i = 0; i < s->nb_streams; i++) {
          AVStream *st = s->streams[i];
          MpegTSWriteStream *ts_st = st->priv_data;
          if (ts_st) {
              av_freep(&ts_st->dvb_ac3_desc);
              av_freep(&ts_st->payload);
              if (ts_st->amux) {
                  avformat_free_context(ts_st->amux);
                  ts_st->amux = NULL;
              }
          }
      }
  
      for (i = 0; i < ts->nb_services; i++) {
          service = ts->services[i];
          av_freep(&service);
      }
      av_freep(&ts->services);
  }
  
  static int mpegts_check_bitstream(struct AVFormatContext *s, const AVPacket *pkt)
  {
      int ret = 1;
      AVStream *st = s->streams[pkt->stream_index];
  
      if (st->codecpar->codec_id == AV_CODEC_ID_H264) {
          if (pkt->size >= 5 && AV_RB32(pkt->data) != 0x0000001 &&
                               (AV_RB24(pkt->data) != 0x000001 ||
                                (st->codecpar->extradata_size > 0 &&
                                 st->codecpar->extradata[0] == 1)))
              ret = ff_stream_add_bitstream_filter(st, "h264_mp4toannexb", NULL);
      } else if (st->codecpar->codec_id == AV_CODEC_ID_HEVC) {
          if (pkt->size >= 5 && AV_RB32(pkt->data) != 0x0000001 &&
                               (AV_RB24(pkt->data) != 0x000001 ||
                                (st->codecpar->extradata_size > 0 &&
                                 st->codecpar->extradata[0] == 1)))
              ret = ff_stream_add_bitstream_filter(st, "hevc_mp4toannexb", NULL);
      }
  
      return ret;
  }
  
  #define OFFSET(x) offsetof(MpegTSWrite, x)
  #define ENC AV_OPT_FLAG_ENCODING_PARAM
  static const AVOption options[] = {
      { "mpegts_transport_stream_id", "Set transport_stream_id field.",
        OFFSET(transport_stream_id), AV_OPT_TYPE_INT, { .i64 = 0x0001 }, 0x0001, 0xffff, ENC },
      { "mpegts_original_network_id", "Set original_network_id field.",
        OFFSET(original_network_id), AV_OPT_TYPE_INT, { .i64 = DVB_PRIVATE_NETWORK_START }, 0x0001, 0xffff, ENC },
      { "mpegts_service_id", "Set service_id field.",
        OFFSET(service_id), AV_OPT_TYPE_INT, { .i64 = 0x0001 }, 0x0001, 0xffff, ENC },
      { "mpegts_service_type", "Set service_type field.",
        OFFSET(service_type), AV_OPT_TYPE_INT, { .i64 = 0x01 }, 0x01, 0xff, ENC, "mpegts_service_type" },
      { "digital_tv", "Digital Television.",
        0, AV_OPT_TYPE_CONST, { .i64 = MPEGTS_SERVICE_TYPE_DIGITAL_TV }, 0x01, 0xff, ENC, "mpegts_service_type" },
      { "digital_radio", "Digital Radio.",
        0, AV_OPT_TYPE_CONST, { .i64 = MPEGTS_SERVICE_TYPE_DIGITAL_RADIO }, 0x01, 0xff, ENC, "mpegts_service_type" },
      { "teletext", "Teletext.",
        0, AV_OPT_TYPE_CONST, { .i64 = MPEGTS_SERVICE_TYPE_TELETEXT }, 0x01, 0xff, ENC, "mpegts_service_type" },
      { "advanced_codec_digital_radio", "Advanced Codec Digital Radio.",
        0, AV_OPT_TYPE_CONST, { .i64 = MPEGTS_SERVICE_TYPE_ADVANCED_CODEC_DIGITAL_RADIO }, 0x01, 0xff, ENC, "mpegts_service_type" },
      { "mpeg2_digital_hdtv", "MPEG2 Digital HDTV.",
        0, AV_OPT_TYPE_CONST, { .i64 = MPEGTS_SERVICE_TYPE_MPEG2_DIGITAL_HDTV }, 0x01, 0xff, ENC, "mpegts_service_type" },
      { "advanced_codec_digital_sdtv", "Advanced Codec Digital SDTV.",
        0, AV_OPT_TYPE_CONST, { .i64 = MPEGTS_SERVICE_TYPE_ADVANCED_CODEC_DIGITAL_SDTV }, 0x01, 0xff, ENC, "mpegts_service_type" },
      { "advanced_codec_digital_hdtv", "Advanced Codec Digital HDTV.",
        0, AV_OPT_TYPE_CONST, { .i64 = MPEGTS_SERVICE_TYPE_ADVANCED_CODEC_DIGITAL_HDTV }, 0x01, 0xff, ENC, "mpegts_service_type" },
      { "hevc_digital_hdtv", "HEVC Digital Television Service.",
        0, AV_OPT_TYPE_CONST, { .i64 = MPEGTS_SERVICE_TYPE_HEVC_DIGITAL_HDTV }, 0x01, 0xff, ENC, "mpegts_service_type" },
      { "mpegts_pmt_start_pid", "Set the first pid of the PMT.",
        OFFSET(pmt_start_pid), AV_OPT_TYPE_INT, { .i64 = 0x1000 }, FIRST_OTHER_PID, LAST_OTHER_PID, ENC },
      { "mpegts_start_pid", "Set the first pid.",
        OFFSET(start_pid), AV_OPT_TYPE_INT, { .i64 = 0x0100 }, FIRST_OTHER_PID, LAST_OTHER_PID, ENC },
      { "mpegts_m2ts_mode", "Enable m2ts mode.", OFFSET(m2ts_mode), AV_OPT_TYPE_BOOL, { .i64 = -1 }, -1, 1, ENC },
      { "muxrate", NULL, OFFSET(mux_rate), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, INT_MAX, ENC },
      { "pes_payload_size", "Minimum PES packet payload in bytes",
        OFFSET(pes_payload_size), AV_OPT_TYPE_INT, { .i64 = DEFAULT_PES_PAYLOAD_SIZE }, 0, INT_MAX, ENC },
      { "mpegts_flags", "MPEG-TS muxing flags", OFFSET(flags), AV_OPT_TYPE_FLAGS, { .i64 = 0 }, 0, INT_MAX, ENC, "mpegts_flags" },
      { "resend_headers", "Reemit PAT/PMT before writing the next packet",
        0, AV_OPT_TYPE_CONST, { .i64 = MPEGTS_FLAG_REEMIT_PAT_PMT }, 0, INT_MAX, ENC, "mpegts_flags" },
      { "latm", "Use LATM packetization for AAC",
        0, AV_OPT_TYPE_CONST, { .i64 = MPEGTS_FLAG_AAC_LATM }, 0, INT_MAX, ENC, "mpegts_flags" },
      { "pat_pmt_at_frames", "Reemit PAT and PMT at each video frame",
        0, AV_OPT_TYPE_CONST, { .i64 = MPEGTS_FLAG_PAT_PMT_AT_FRAMES}, 0, INT_MAX, ENC, "mpegts_flags" },
      { "system_b", "Conform to System B (DVB) instead of System A (ATSC)",
        0, AV_OPT_TYPE_CONST, { .i64 = MPEGTS_FLAG_SYSTEM_B }, 0, INT_MAX, ENC, "mpegts_flags" },
      { "initial_discontinuity", "Mark initial packets as discontinuous",
        0, AV_OPT_TYPE_CONST, { .i64 = MPEGTS_FLAG_DISCONT }, 0, INT_MAX, ENC, "mpegts_flags" },
      { "mpegts_copyts", "don't offset dts/pts", OFFSET(copyts), AV_OPT_TYPE_BOOL, { .i64 = -1 }, -1, 1, ENC },
      { "tables_version", "set PAT, PMT and SDT version", OFFSET(tables_version), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 31, ENC },
      { "omit_video_pes_length", "Omit the PES packet length for video packets",
        OFFSET(omit_video_pes_length), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, ENC },
      { "pcr_period", "PCR retransmission time in milliseconds",
        OFFSET(pcr_period_ms), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, INT_MAX, ENC },
      { "pat_period", "PAT/PMT retransmission time limit in seconds",
        OFFSET(pat_period_us), AV_OPT_TYPE_DURATION, { .i64 = PAT_RETRANS_TIME * 1000LL }, 0, INT64_MAX, ENC },
      { "sdt_period", "SDT retransmission time limit in seconds",
        OFFSET(sdt_period_us), AV_OPT_TYPE_DURATION, { .i64 = SDT_RETRANS_TIME * 1000LL }, 0, INT64_MAX, ENC },
      { NULL },
  };
  
  static const AVClass mpegts_muxer_class = {
      .class_name = "MPEGTS muxer",
      .item_name  = av_default_item_name,
      .option     = options,
      .version    = LIBAVUTIL_VERSION_INT,
  };
  
  AVOutputFormat ff_mpegts_muxer = {
      .name           = "mpegts",
      .long_name      = NULL_IF_CONFIG_SMALL("MPEG-TS (MPEG-2 Transport Stream)"),
      .mime_type      = "video/MP2T",
      .extensions     = "ts,m2t,m2ts,mts",
      .priv_data_size = sizeof(MpegTSWrite),
      .audio_codec    = AV_CODEC_ID_MP2,
      .video_codec    = AV_CODEC_ID_MPEG2VIDEO,
      .init           = mpegts_init,
      .write_packet   = mpegts_write_packet,
      .write_trailer  = mpegts_write_end,
      .deinit         = mpegts_deinit,
      .check_bitstream = mpegts_check_bitstream,
      .flags          = AVFMT_ALLOW_FLUSH | AVFMT_VARIABLE_FPS | AVFMT_NODIMENSIONS,
      .priv_class     = &mpegts_muxer_class,
  };
  