text: /*
   * copyright (c) 2007 Luca Abeni
   *
   * 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 <string.h>
  #include "libavutil/avstring.h"
  #include "libavutil/base64.h"
  #include "libavutil/dict.h"
  #include "libavutil/parseutils.h"
  #include "libavutil/opt.h"
  #include "libavcodec/xiph.h"
  #include "libavcodec/mpeg4audio.h"
  #include "avformat.h"
  #include "internal.h"
  #include "avc.h"
  #include "rtp.h"
  #if CONFIG_NETWORK
  #include "network.h"
  #endif
  
  #if CONFIG_RTP_MUXER
  #define MAX_EXTRADATA_SIZE ((INT_MAX - 10) / 2)
  
  struct sdp_session_level {
      int sdp_version;      /**< protocol version (currently 0) */
      int id;               /**< session ID */
      int version;          /**< session version */
      int start_time;       /**< session start time (NTP time, in seconds),
                                 or 0 in case of permanent session */
      int end_time;         /**< session end time (NTP time, in seconds),
                                 or 0 if the session is not bounded */
      int ttl;              /**< TTL, in case of multicast stream */
      const char *user;     /**< username of the session's creator */
      const char *src_addr; /**< IP address of the machine from which the session was created */
      const char *src_type; /**< address type of src_addr */
      const char *dst_addr; /**< destination IP address (can be multicast) */
      const char *dst_type; /**< destination IP address type */
      const char *name;     /**< session name (can be an empty string) */
  };
  
  static void sdp_write_address(char *buff, int size, const char *dest_addr,
                                const char *dest_type, int ttl)
  {
      if (dest_addr) {
          if (!dest_type)
              dest_type = "IP4";
          if (ttl > 0 && !strcmp(dest_type, "IP4")) {
              /* The TTL should only be specified for IPv4 multicast addresses,
               * not for IPv6. */
              av_strlcatf(buff, size, "c=IN %s %s/%d\r\n", dest_type, dest_addr, ttl);
          } else {
              av_strlcatf(buff, size, "c=IN %s %s\r\n", dest_type, dest_addr);
          }
      }
  }
  
  static void sdp_write_header(char *buff, int size, struct sdp_session_level *s)
  {
      av_strlcatf(buff, size, "v=%d\r\n"
                              "o=- %d %d IN %s %s\r\n"
                              "s=%s\r\n",
                              s->sdp_version,
                              s->id, s->version, s->src_type, s->src_addr,
                              s->name);
      sdp_write_address(buff, size, s->dst_addr, s->dst_type, s->ttl);
      av_strlcatf(buff, size, "t=%d %d\r\n"
                              "a=tool:libavformat " AV_STRINGIFY(LIBAVFORMAT_VERSION) "\r\n",
                              s->start_time, s->end_time);
  }
  
  #if CONFIG_NETWORK
  static int resolve_destination(char *dest_addr, int size, char *type,
                                 int type_size)
  {
      struct addrinfo hints = { 0 }, *ai;
      int is_multicast;
  
      av_strlcpy(type, "IP4", type_size);
      if (!dest_addr[0])
          return 0;
  
      /* Resolve the destination, since it must be written
       * as a numeric IP address in the SDP. */
  
      if (getaddrinfo(dest_addr, NULL, &hints, &ai))
          return 0;
      getnameinfo(ai->ai_addr, ai->ai_addrlen, dest_addr, size,
                  NULL, 0, NI_NUMERICHOST);
  #ifdef AF_INET6
      if (ai->ai_family == AF_INET6)
          av_strlcpy(type, "IP6", type_size);
  #endif
      is_multicast = ff_is_multicast_address(ai->ai_addr);
      freeaddrinfo(ai);
      return is_multicast;
  }
  #else
  static int resolve_destination(char *dest_addr, int size, char *type,
                                 int type_size)
  {
      return 0;
  }
  #endif
  
  static int sdp_get_address(char *dest_addr, int size, int *ttl, const char *url)
  {
      int port;
      const char *p;
      char proto[32];
  
      av_url_split(proto, sizeof(proto), NULL, 0, dest_addr, size, &port, NULL, 0, url);
  
      *ttl = 0;
  
      if (strcmp(proto, "rtp")) {
          /* The url isn't for the actual rtp sessions,
           * don't parse out anything else than the destination.
           */
          return 0;
      }
  
      p = strchr(url, '?');
      if (p) {
          char buff[64];
  
          if (av_find_info_tag(buff, sizeof(buff), "ttl", p)) {
              *ttl = strtol(buff, NULL, 10);
          } else {
              *ttl = 5;
          }
      }
  
      return port;
  }
  
  #define MAX_PSET_SIZE 1024
  static char *extradata2psets(AVCodecContext *c)
  {
      char *psets, *p;
      const uint8_t *r;
      static const char pset_string[] = "; sprop-parameter-sets=";
      static const char profile_string[] = "; profile-level-id=";
      uint8_t *orig_extradata = NULL;
      int orig_extradata_size = 0;
      const uint8_t *sps = NULL, *sps_end;
  
      if (c->extradata_size > MAX_EXTRADATA_SIZE) {
          av_log(c, AV_LOG_ERROR, "Too much extradata!\n");
  
          return NULL;
      }
      if (c->extradata[0] == 1) {
          uint8_t *dummy_p;
          int dummy_int;
          AVBitStreamFilterContext *bsfc= av_bitstream_filter_init("h264_mp4toannexb");
  
          if (!bsfc) {
              av_log(c, AV_LOG_ERROR, "Cannot open the h264_mp4toannexb BSF!\n");
  
              return NULL;
          }
  
          orig_extradata_size = c->extradata_size;
          orig_extradata = av_mallocz(orig_extradata_size +
                                      FF_INPUT_BUFFER_PADDING_SIZE);
          if (!orig_extradata) {
              av_bitstream_filter_close(bsfc);
              return NULL;
          }
          memcpy(orig_extradata, c->extradata, orig_extradata_size);
          av_bitstream_filter_filter(bsfc, c, NULL, &dummy_p, &dummy_int, NULL, 0, 0);
          av_bitstream_filter_close(bsfc);
      }
  
      psets = av_mallocz(MAX_PSET_SIZE);
      if (psets == NULL) {
          av_log(c, AV_LOG_ERROR, "Cannot allocate memory for the parameter sets.\n");
          av_free(orig_extradata);
          return NULL;
      }
      memcpy(psets, pset_string, strlen(pset_string));
      p = psets + strlen(pset_string);
      r = ff_avc_find_startcode(c->extradata, c->extradata + c->extradata_size);
      while (r < c->extradata + c->extradata_size) {
          const uint8_t *r1;
          uint8_t nal_type;
  
          while (!*(r++));
          nal_type = *r & 0x1f;
          r1 = ff_avc_find_startcode(r, c->extradata + c->extradata_size);
          if (nal_type != 7 && nal_type != 8) { /* Only output SPS and PPS */
              r = r1;
              continue;
          }
          if (p != (psets + strlen(pset_string))) {
              *p = ',';
              p++;
          }
          if (!sps) {
              sps = r;
              sps_end = r1;
          }
          if (av_base64_encode(p, MAX_PSET_SIZE - (p - psets), r, r1 - r) == NULL) {
              av_log(c, AV_LOG_ERROR, "Cannot Base64-encode %td %td!\n", MAX_PSET_SIZE - (p - psets), r1 - r);
              av_free(psets);
  
              return NULL;
          }
          p += strlen(p);
          r = r1;
      }
      if (sps && sps_end - sps >= 4) {
          memcpy(p, profile_string, strlen(profile_string));
          p += strlen(p);
          ff_data_to_hex(p, sps + 1, 3, 0);
          p[6] = '\0';
      }
      if (orig_extradata) {
          av_free(c->extradata);
          c->extradata      = orig_extradata;
          c->extradata_size = orig_extradata_size;
      }
  
      return psets;
  }
  
  static char *extradata2config(AVCodecContext *c)
  {
      char *config;
  
      if (c->extradata_size > MAX_EXTRADATA_SIZE) {
          av_log(c, AV_LOG_ERROR, "Too much extradata!\n");
  
          return NULL;
      }
      config = av_malloc(10 + c->extradata_size * 2);
      if (config == NULL) {
          av_log(c, AV_LOG_ERROR, "Cannot allocate memory for the config info.\n");
          return NULL;
      }
      memcpy(config, "; config=", 9);
      ff_data_to_hex(config + 9, c->extradata, c->extradata_size, 0);
      config[9 + c->extradata_size * 2] = 0;
  
      return config;
  }
  
  static char *xiph_extradata2config(AVCodecContext *c)
  {
      char *config, *encoded_config;
      uint8_t *header_start[3];
      int headers_len, header_len[3], config_len;
      int first_header_size;
  
      switch (c->codec_id) {
      case AV_CODEC_ID_THEORA:
          first_header_size = 42;
          break;
      case AV_CODEC_ID_VORBIS:
          first_header_size = 30;
          break;
      default:
          av_log(c, AV_LOG_ERROR, "Unsupported Xiph codec ID\n");
          return NULL;
      }
  
      if (avpriv_split_xiph_headers(c->extradata, c->extradata_size,
                                first_header_size, header_start,
                                header_len) < 0) {
          av_log(c, AV_LOG_ERROR, "Extradata corrupt.\n");
          return NULL;
      }
  
      headers_len = header_len[0] + header_len[2];
      config_len = 4 +          // count
                   3 +          // ident
                   2 +          // packet size
                   1 +          // header count
                   2 +          // header size
                   headers_len; // and the rest
  
      config = av_malloc(config_len);
      if (!config)
          goto xiph_fail;
  
      encoded_config = av_malloc(AV_BASE64_SIZE(config_len));
      if (!encoded_config) {
          av_free(config);
          goto xiph_fail;
      }
  
      config[0] = config[1] = config[2] = 0;
      config[3] = 1;
      config[4] = (RTP_XIPH_IDENT >> 16) & 0xff;
      config[5] = (RTP_XIPH_IDENT >>  8) & 0xff;
      config[6] = (RTP_XIPH_IDENT      ) & 0xff;
      config[7] = (headers_len >> 8) & 0xff;
      config[8] = headers_len & 0xff;
      config[9] = 2;
      config[10] = header_len[0];
      config[11] = 0; // size of comment header; nonexistent
      memcpy(config + 12, header_start[0], header_len[0]);
      memcpy(config + 12 + header_len[0], header_start[2], header_len[2]);
  
      av_base64_encode(encoded_config, AV_BASE64_SIZE(config_len),
                       config, config_len);
      av_free(config);
  
      return encoded_config;
  
  xiph_fail:
      av_log(c, AV_LOG_ERROR,
             "Not enough memory for configuration string\n");
      return NULL;
  }
  
  static int latm_context2profilelevel(AVCodecContext *c)
  {
      /* MP4A-LATM
       * The RTP payload format specification is described in RFC 3016
       * The encoding specifications are provided in ISO/IEC 14496-3 */
  
      int profile_level = 0x2B;
  
      /* TODO: AAC Profile only supports AAC LC Object Type.
       * Different Object Types should implement different Profile Levels */
  
      if (c->sample_rate <= 24000) {
          if (c->channels <= 2)
              profile_level = 0x28; // AAC Profile, Level 1
      } else if (c->sample_rate <= 48000) {
          if (c->channels <= 2) {
              profile_level = 0x29; // AAC Profile, Level 2
          } else if (c->channels <= 5) {
              profile_level = 0x2A; // AAC Profile, Level 4
          }
      } else if (c->sample_rate <= 96000) {
          if (c->channels <= 5) {
              profile_level = 0x2B; // AAC Profile, Level 5
          }
      }
  
      return profile_level;
  }
  
  static char *latm_context2config(AVCodecContext *c)
  {
      /* MP4A-LATM
       * The RTP payload format specification is described in RFC 3016
       * The encoding specifications are provided in ISO/IEC 14496-3 */
  
      uint8_t config_byte[6];
      int rate_index;
      char *config;
  
      for (rate_index = 0; rate_index < 16; rate_index++)
          if (avpriv_mpeg4audio_sample_rates[rate_index] == c->sample_rate)
              break;
      if (rate_index == 16) {
          av_log(c, AV_LOG_ERROR, "Unsupported sample rate\n");
          return NULL;
      }
  
      config_byte[0] = 0x40;
      config_byte[1] = 0;
      config_byte[2] = 0x20 | rate_index;
      config_byte[3] = c->channels << 4;
      config_byte[4] = 0x3f;
      config_byte[5] = 0xc0;
  
      config = av_malloc(6*2+1);
      if (!config) {
          av_log(c, AV_LOG_ERROR, "Cannot allocate memory for the config info.\n");
          return NULL;
      }
      ff_data_to_hex(config, config_byte, 6, 1);
      config[12] = 0;
  
      return config;
  }
  
  static char *sdp_write_media_attributes(char *buff, int size, AVCodecContext *c, int payload_type, AVFormatContext *fmt)
  {
      char *config = NULL;
  
      switch (c->codec_id) {
          case AV_CODEC_ID_H264: {
              int mode = 1;
              if (fmt && fmt->oformat->priv_class &&
                  av_opt_flag_is_set(fmt->priv_data, "rtpflags", "h264_mode0"))
                  mode = 0;
              if (c->extradata_size) {
                  config = extradata2psets(c);
              }
              av_strlcatf(buff, size, "a=rtpmap:%d H264/90000\r\n"
                                      "a=fmtp:%d packetization-mode=%d%s\r\n",
                                       payload_type,
                                       payload_type, mode, config ? config : "");
              break;
          }
          case AV_CODEC_ID_H263:
          case AV_CODEC_ID_H263P:
              /* a=framesize is required by 3GPP TS 26.234 (PSS). It
               * actually specifies the maximum video size, but we only know
               * the current size. This is required for playback on Android
               * stagefright and on Samsung bada. */
              if (!fmt || !fmt->oformat->priv_class ||
                  !av_opt_flag_is_set(fmt->priv_data, "rtpflags", "rfc2190") ||
                  c->codec_id == AV_CODEC_ID_H263P)
              av_strlcatf(buff, size, "a=rtpmap:%d H263-2000/90000\r\n"
                                      "a=framesize:%d %d-%d\r\n",
                                      payload_type,
                                      payload_type, c->width, c->height);
              break;
          case AV_CODEC_ID_MPEG4:
              if (c->extradata_size) {
                  config = extradata2config(c);
              }
              av_strlcatf(buff, size, "a=rtpmap:%d MP4V-ES/90000\r\n"
                                      "a=fmtp:%d profile-level-id=1%s\r\n",
                                       payload_type,
                                       payload_type, config ? config : "");
              break;
          case AV_CODEC_ID_AAC:
              if (fmt && fmt->oformat && fmt->oformat->priv_class &&
                  av_opt_flag_is_set(fmt->priv_data, "rtpflags", "latm")) {
                  config = latm_context2config(c);
                  if (!config)
                      return NULL;
                  av_strlcatf(buff, size, "a=rtpmap:%d MP4A-LATM/%d/%d\r\n"
                                          "a=fmtp:%d profile-level-id=%d;cpresent=0;config=%s\r\n",
                                           payload_type, c->sample_rate, c->channels,
                                           payload_type, latm_context2profilelevel(c), config);
              } else {
                  if (c->extradata_size) {
                      config = extradata2config(c);
                  } else {
                      /* FIXME: maybe we can forge config information based on the
                       *        codec parameters...
                       */
                      av_log(c, AV_LOG_ERROR, "AAC with no global headers is currently not supported.\n");
                      return NULL;
                  }
                  if (config == NULL) {
                      return NULL;
                  }
                  av_strlcatf(buff, size, "a=rtpmap:%d MPEG4-GENERIC/%d/%d\r\n"
                                          "a=fmtp:%d profile-level-id=1;"
                                          "mode=AAC-hbr;sizelength=13;indexlength=3;"
                                          "indexdeltalength=3%s\r\n",
                                           payload_type, c->sample_rate, c->channels,
                                           payload_type, config);
              }
              break;
          case AV_CODEC_ID_PCM_S16BE:
              if (payload_type >= RTP_PT_PRIVATE)
                  av_strlcatf(buff, size, "a=rtpmap:%d L16/%d/%d\r\n",
                                           payload_type,
                                           c->sample_rate, c->channels);
              break;
          case AV_CODEC_ID_PCM_MULAW:
              if (payload_type >= RTP_PT_PRIVATE)
                  av_strlcatf(buff, size, "a=rtpmap:%d PCMU/%d/%d\r\n",
                                           payload_type,
                                           c->sample_rate, c->channels);
              break;
          case AV_CODEC_ID_PCM_ALAW:
              if (payload_type >= RTP_PT_PRIVATE)
                  av_strlcatf(buff, size, "a=rtpmap:%d PCMA/%d/%d\r\n",
                                           payload_type,
                                           c->sample_rate, c->channels);
              break;
          case AV_CODEC_ID_AMR_NB:
              av_strlcatf(buff, size, "a=rtpmap:%d AMR/%d/%d\r\n"
                                      "a=fmtp:%d octet-align=1\r\n",
                                       payload_type, c->sample_rate, c->channels,
                                       payload_type);
              break;
          case AV_CODEC_ID_AMR_WB:
              av_strlcatf(buff, size, "a=rtpmap:%d AMR-WB/%d/%d\r\n"
                                      "a=fmtp:%d octet-align=1\r\n",
                                       payload_type, c->sample_rate, c->channels,
                                       payload_type);
              break;
          case AV_CODEC_ID_VORBIS:
              if (c->extradata_size)
                  config = xiph_extradata2config(c);
              else
                  av_log(c, AV_LOG_ERROR, "Vorbis configuration info missing\n");
              if (!config)
                  return NULL;
  
              av_strlcatf(buff, size, "a=rtpmap:%d vorbis/%d/%d\r\n"
                                      "a=fmtp:%d configuration=%s\r\n",
                                      payload_type, c->sample_rate, c->channels,
                                      payload_type, config);
              break;
          case AV_CODEC_ID_THEORA: {
              const char *pix_fmt;
              if (c->extradata_size)
                  config = xiph_extradata2config(c);
              else
                  av_log(c, AV_LOG_ERROR, "Theora configuation info missing\n");
              if (!config)
                  return NULL;
  
              switch (c->pix_fmt) {
              case AV_PIX_FMT_YUV420P:
                  pix_fmt = "YCbCr-4:2:0";
                  break;
              case AV_PIX_FMT_YUV422P:
                  pix_fmt = "YCbCr-4:2:2";
                  break;
              case AV_PIX_FMT_YUV444P:
                  pix_fmt = "YCbCr-4:4:4";
                  break;
              default:
                  av_log(c, AV_LOG_ERROR, "Unsupported pixel format.\n");
                  return NULL;
              }
  
              av_strlcatf(buff, size, "a=rtpmap:%d theora/90000\r\n"
                                      "a=fmtp:%d delivery-method=inline; "
                                      "width=%d; height=%d; sampling=%s; "
                                      "configuration=%s\r\n",
                                      payload_type, payload_type,
                                      c->width, c->height, pix_fmt, config);
              break;
          }
          case AV_CODEC_ID_VP8:
              av_strlcatf(buff, size, "a=rtpmap:%d VP8/90000\r\n",
                                       payload_type);
              break;
          case AV_CODEC_ID_MJPEG:
              if (payload_type >= RTP_PT_PRIVATE)
                  av_strlcatf(buff, size, "a=rtpmap:%d JPEG/90000\r\n",
                                           payload_type);
              break;
          case AV_CODEC_ID_ADPCM_G722:
              if (payload_type >= RTP_PT_PRIVATE)
                  av_strlcatf(buff, size, "a=rtpmap:%d G722/%d/%d\r\n",
                                           payload_type,
                                           8000, c->channels);
              break;
          case AV_CODEC_ID_ADPCM_G726: {
              if (payload_type >= RTP_PT_PRIVATE)
                  av_strlcatf(buff, size, "a=rtpmap:%d G726-%d/%d\r\n",
                                           payload_type,
                                           c->bits_per_coded_sample*8,
                                           c->sample_rate);
              break;
          }
          case AV_CODEC_ID_ILBC:
              av_strlcatf(buff, size, "a=rtpmap:%d iLBC/%d\r\n"
                                      "a=fmtp:%d mode=%d\r\n",
                                       payload_type, c->sample_rate,
                                       payload_type, c->block_align == 38 ? 20 : 30);
              break;
          case AV_CODEC_ID_SPEEX:
              av_strlcatf(buff, size, "a=rtpmap:%d speex/%d\r\n",
                                       payload_type, c->sample_rate);
              if (c->codec) {
                  const char *mode;
                  uint64_t vad_option;
  
                  if (c->flags & CODEC_FLAG_QSCALE)
                        mode = "on";
                  else if (!av_opt_get_int(c, "vad", AV_OPT_FLAG_ENCODING_PARAM, &vad_option) && vad_option)
                        mode = "vad";
                  else
                        mode = "off";
  
                  av_strlcatf(buff, size, "a=fmtp:%d vbr=%s\r\n",
                                          payload_type, mode);
              }
              break;
          case AV_CODEC_ID_OPUS:
              av_strlcatf(buff, size, "a=rtpmap:%d opus/48000\r\n",
                                       payload_type);
              break;
          default:
              /* Nothing special to do here... */
              break;
      }
  
      av_free(config);
  
      return buff;
  }
  
  void ff_sdp_write_media(char *buff, int size, AVStream *st, int idx,
                          const char *dest_addr, const char *dest_type,
                          int port, int ttl, AVFormatContext *fmt)
  {
      AVCodecContext *c = st->codec;
      const char *type;
      int payload_type;
  
      payload_type = ff_rtp_get_payload_type(fmt, c, idx);
  
      switch (c->codec_type) {
          case AVMEDIA_TYPE_VIDEO   : type = "video"      ; break;
          case AVMEDIA_TYPE_AUDIO   : type = "audio"      ; break;
          case AVMEDIA_TYPE_SUBTITLE: type = "text"       ; break;
          default                 : type = "application"; break;
      }
  
      av_strlcatf(buff, size, "m=%s %d RTP/AVP %d\r\n", type, port, payload_type);
      sdp_write_address(buff, size, dest_addr, dest_type, ttl);
      if (c->bit_rate) {
          av_strlcatf(buff, size, "b=AS:%d\r\n", c->bit_rate / 1000);
      }
  
      sdp_write_media_attributes(buff, size, c, payload_type, fmt);
  }
  
  int av_sdp_create(AVFormatContext *ac[], int n_files, char *buf, int size)
  {
      AVDictionaryEntry *title = av_dict_get(ac[0]->metadata, "title", NULL, 0);
      struct sdp_session_level s = { 0 };
      int i, j, port, ttl, is_multicast, index = 0;
      char dst[32], dst_type[5];
  
      memset(buf, 0, size);
      s.user = "-";
      s.src_addr = "127.0.0.1";    /* FIXME: Properly set this */
      s.src_type = "IP4";
      s.name = title ? title->value : "No Name";
  
      port = 0;
      ttl = 0;
      if (n_files == 1) {
          port = sdp_get_address(dst, sizeof(dst), &ttl, ac[0]->filename);
          is_multicast = resolve_destination(dst, sizeof(dst), dst_type,
                                             sizeof(dst_type));
          if (!is_multicast)
              ttl = 0;
          if (dst[0]) {
              s.dst_addr = dst;
              s.dst_type = dst_type;
              s.ttl = ttl;
              if (!strcmp(dst_type, "IP6")) {
                  s.src_addr = "::1";
                  s.src_type = "IP6";
              }
          }
      }
      sdp_write_header(buf, size, &s);
  
      dst[0] = 0;
      for (i = 0; i < n_files; i++) {
          if (n_files != 1) {
              port = sdp_get_address(dst, sizeof(dst), &ttl, ac[i]->filename);
              is_multicast = resolve_destination(dst, sizeof(dst), dst_type,
                                                 sizeof(dst_type));
              if (!is_multicast)
                  ttl = 0;
          }
          for (j = 0; j < ac[i]->nb_streams; j++) {
              ff_sdp_write_media(buf, size, ac[i]->streams[j], index++,
                                 dst[0] ? dst : NULL, dst_type,
                                 (port > 0) ? port + j * 2 : 0,
                                 ttl, ac[i]);
              if (port <= 0) {
                  av_strlcatf(buf, size,
                                     "a=control:streamid=%d\r\n", i + j);
              }
          }
      }
  
      return 0;
  }
  #else
  int av_sdp_create(AVFormatContext *ac[], int n_files, char *buf, int size)
  {
      return AVERROR(ENOSYS);
  }
  
  void ff_sdp_write_media(char *buff, int size, AVStream *st, int idx,
                          const char *dest_addr, const char *dest_type,
                          int port, int ttl, AVFormatContext *fmt)
  {
  }
  #endif
  