libavformat/movenc.c:1610: error: Null Dereference
  pointer `null` is dereferenced by call to `ff_sdp_write_media()` at line 1610, column 5.

libavformat/movenc.c:1604:1: start of procedure mov_write_udta_sdp()
1602. }
1603. 
1604. static int mov_write_udta_sdp(AVIOContext *pb, MOVTrack *track)
      ^
1605. {
1606.     AVFormatContext *ctx = track->rtp_ctx;

libavformat/movenc.c:1606:5: 
1604. static int mov_write_udta_sdp(AVIOContext *pb, MOVTrack *track)
1605. {
1606.     AVFormatContext *ctx = track->rtp_ctx;
          ^
1607.     char buf[1000] = "";
1608.     int len;

libavformat/movenc.c:1607:5: 
1605. {
1606.     AVFormatContext *ctx = track->rtp_ctx;
1607.     char buf[1000] = "";
          ^
1608.     int len;
1609. 

libavformat/movenc.c:1610:5: 
1608.     int len;
1609. 
1610.     ff_sdp_write_media(buf, sizeof(buf), ctx->streams[0], track->src_track,
          ^
1611.                        NULL, NULL, 0, 0, ctx);
1612.     av_strlcatf(buf, sizeof(buf), "a=control:streamid=%d\r\n", track->track_id);

libavformat/sdp.c:593:1: start of procedure ff_sdp_write_media()
  591. }
  592. 
  593. void ff_sdp_write_media(char *buff, int size, AVStream *st, int idx,
       ^
  594.                         const char *dest_addr, const char *dest_type,
  595.                         int port, int ttl, AVFormatContext *fmt)

libavformat/sdp.c:597:5: 
  595.                         int port, int ttl, AVFormatContext *fmt)
  596. {
  597.     AVCodecContext *c = st->codec;
           ^
  598.     const char *type;
  599.     int payload_type;

libavformat/sdp.c:601:5: Skipping ff_rtp_get_payload_type(): empty list of specs
  599.     int payload_type;
  600. 
  601.     payload_type = ff_rtp_get_payload_type(fmt, c, idx);
           ^
  602. 
  603.     switch (c->codec_type) {

libavformat/sdp.c:603:5: 
  601.     payload_type = ff_rtp_get_payload_type(fmt, c, idx);
  602. 
  603.     switch (c->codec_type) {
           ^
  604.         case AVMEDIA_TYPE_VIDEO   : type = "video"      ; break;
  605.         case AVMEDIA_TYPE_AUDIO   : type = "audio"      ; break;

libavformat/sdp.c:604:9: Switch condition is false. Skipping switch case
  602. 
  603.     switch (c->codec_type) {
  604.         case AVMEDIA_TYPE_VIDEO   : type = "video"      ; break;
               ^
  605.         case AVMEDIA_TYPE_AUDIO   : type = "audio"      ; break;
  606.         case AVMEDIA_TYPE_SUBTITLE: type = "text"       ; break;

libavformat/sdp.c:605:9: Switch condition is false. Skipping switch case
  603.     switch (c->codec_type) {
  604.         case AVMEDIA_TYPE_VIDEO   : type = "video"      ; break;
  605.         case AVMEDIA_TYPE_AUDIO   : type = "audio"      ; break;
               ^
  606.         case AVMEDIA_TYPE_SUBTITLE: type = "text"       ; break;
  607.         default                 : type = "application"; break;

libavformat/sdp.c:606:9: Switch condition is false. Skipping switch case
  604.         case AVMEDIA_TYPE_VIDEO   : type = "video"      ; break;
  605.         case AVMEDIA_TYPE_AUDIO   : type = "audio"      ; break;
  606.         case AVMEDIA_TYPE_SUBTITLE: type = "text"       ; break;
               ^
  607.         default                 : type = "application"; break;
  608.     }

libavformat/sdp.c:607:35: 
  605.         case AVMEDIA_TYPE_AUDIO   : type = "audio"      ; break;
  606.         case AVMEDIA_TYPE_SUBTITLE: type = "text"       ; break;
  607.         default                 : type = "application"; break;
                                         ^
  608.     }
  609. 

libavformat/sdp.c:610:5: 
  608.     }
  609. 
  610.     av_strlcatf(buff, size, "m=%s %d RTP/AVP %d\r\n", type, port, payload_type);
           ^
  611.     sdp_write_address(buff, size, dest_addr, dest_type, ttl);
  612.     if (c->bit_rate) {

libavutil/avstring.c:99:1: start of procedure av_strlcatf()
     97. }
     98. 
     99. size_t av_strlcatf(char *dst, size_t size, const char *fmt, ...)
         ^
    100. {
    101.     int len = strlen(dst);

libavutil/avstring.c:101:5: 
     99. size_t av_strlcatf(char *dst, size_t size, const char *fmt, ...)
    100. {
    101.     int len = strlen(dst);
             ^
    102.     va_list vl;
    103. 

libavutil/avstring.c:104:5: 
    102.     va_list vl;
    103. 
    104.     va_start(vl, fmt);
             ^
    105.     len += vsnprintf(dst + len, size > len ? size - len : 0, fmt, vl);
    106.     va_end(vl);

libavutil/avstring.c:105:33: Condition is true
    103. 
    104.     va_start(vl, fmt);
    105.     len += vsnprintf(dst + len, size > len ? size - len : 0, fmt, vl);
                                         ^
    106.     va_end(vl);
    107. 

libavutil/avstring.c:105:5: 
    103. 
    104.     va_start(vl, fmt);
    105.     len += vsnprintf(dst + len, size > len ? size - len : 0, fmt, vl);
             ^
    106.     va_end(vl);
    107. 

libavutil/avstring.c:106:5: 
    104.     va_start(vl, fmt);
    105.     len += vsnprintf(dst + len, size > len ? size - len : 0, fmt, vl);
    106.     va_end(vl);
             ^
    107. 
    108.     return len;

libavutil/avstring.c:108:5: 
    106.     va_end(vl);
    107. 
    108.     return len;
             ^
    109. }
    110. 

libavutil/avstring.c:109:1: return from a call to av_strlcatf
    107. 
    108.     return len;
    109. }
         ^
    110. 
    111. char *av_d2str(double d)

libavformat/sdp.c:611:5: 
  609. 
  610.     av_strlcatf(buff, size, "m=%s %d RTP/AVP %d\r\n", type, port, payload_type);
  611.     sdp_write_address(buff, size, dest_addr, dest_type, ttl);
           ^
  612.     if (c->bit_rate) {
  613.         av_strlcatf(buff, size, "b=AS:%d\r\n", c->bit_rate / 1000);

libavformat/sdp.c:57:1: start of procedure sdp_write_address()
    55. };
    56. 
    57. static void sdp_write_address(char *buff, int size, const char *dest_addr,
        ^
    58.                               const char *dest_type, int ttl)
    59. {

libavformat/sdp.c:60:9: Taking true branch
    58.                               const char *dest_type, int ttl)
    59. {
    60.     if (dest_addr) {
                ^
    61.         if (!dest_type)
    62.             dest_type = "IP4";

libavformat/sdp.c:61:14: Taking false branch
    59. {
    60.     if (dest_addr) {
    61.         if (!dest_type)
                     ^
    62.             dest_type = "IP4";
    63.         if (ttl > 0 && !strcmp(dest_type, "IP4")) {

libavformat/sdp.c:63:13: Taking true branch
    61.         if (!dest_type)
    62.             dest_type = "IP4";
    63.         if (ttl > 0 && !strcmp(dest_type, "IP4")) {
                    ^
    64.             /* The TTL should only be specified for IPv4 multicast addresses,
    65.              * not for IPv6. */

libavformat/sdp.c:63:25: Taking false branch
    61.         if (!dest_type)
    62.             dest_type = "IP4";
    63.         if (ttl > 0 && !strcmp(dest_type, "IP4")) {
                                ^
    64.             /* The TTL should only be specified for IPv4 multicast addresses,
    65.              * not for IPv6. */

libavformat/sdp.c:68:13: 
    66.             av_strlcatf(buff, size, "c=IN %s %s/%d\r\n", dest_type, dest_addr, ttl);
    67.         } else {
    68.             av_strlcatf(buff, size, "c=IN %s %s\r\n", dest_type, dest_addr);
                    ^
    69.         }
    70.     }

libavutil/avstring.c:99:1: start of procedure av_strlcatf()
       97. }
       98. 
       99. size_t av_strlcatf(char *dst, size_t size, const char *fmt, ...)
           ^
      100. {
      101.     int len = strlen(dst);

libavutil/avstring.c:101:5: 
       99. size_t av_strlcatf(char *dst, size_t size, const char *fmt, ...)
      100. {
      101.     int len = strlen(dst);
               ^
      102.     va_list vl;
      103. 

libavutil/avstring.c:104:5: 
      102.     va_list vl;
      103. 
      104.     va_start(vl, fmt);
               ^
      105.     len += vsnprintf(dst + len, size > len ? size - len : 0, fmt, vl);
      106.     va_end(vl);

libavutil/avstring.c:105:33: Condition is true
      103. 
      104.     va_start(vl, fmt);
      105.     len += vsnprintf(dst + len, size > len ? size - len : 0, fmt, vl);
                                           ^
      106.     va_end(vl);
      107. 

libavutil/avstring.c:105:5: 
      103. 
      104.     va_start(vl, fmt);
      105.     len += vsnprintf(dst + len, size > len ? size - len : 0, fmt, vl);
               ^
      106.     va_end(vl);
      107. 

libavutil/avstring.c:106:5: 
      104.     va_start(vl, fmt);
      105.     len += vsnprintf(dst + len, size > len ? size - len : 0, fmt, vl);
      106.     va_end(vl);
               ^
      107. 
      108.     return len;

libavutil/avstring.c:108:5: 
      106.     va_end(vl);
      107. 
      108.     return len;
               ^
      109. }
      110. 

libavutil/avstring.c:109:1: return from a call to av_strlcatf
      107. 
      108.     return len;
      109. }
           ^
      110. 
      111. char *av_d2str(double d)

libavformat/sdp.c:60:5: 
    58.                               const char *dest_type, int ttl)
    59. {
    60.     if (dest_addr) {
            ^
    61.         if (!dest_type)
    62.             dest_type = "IP4";

libavformat/sdp.c:71:1: return from a call to sdp_write_address
    69.         }
    70.     }
    71. }
        ^
    72. 
    73. static void sdp_write_header(char *buff, int size, struct sdp_session_level *s)

libavformat/sdp.c:612:9: Taking true branch
  610.     av_strlcatf(buff, size, "m=%s %d RTP/AVP %d\r\n", type, port, payload_type);
  611.     sdp_write_address(buff, size, dest_addr, dest_type, ttl);
  612.     if (c->bit_rate) {
               ^
  613.         av_strlcatf(buff, size, "b=AS:%d\r\n", c->bit_rate / 1000);
  614.     }

libavformat/sdp.c:613:9: 
  611.     sdp_write_address(buff, size, dest_addr, dest_type, ttl);
  612.     if (c->bit_rate) {
  613.         av_strlcatf(buff, size, "b=AS:%d\r\n", c->bit_rate / 1000);
               ^
  614.     }
  615. 

libavutil/avstring.c:99:1: start of procedure av_strlcatf()
     97. }
     98. 
     99. size_t av_strlcatf(char *dst, size_t size, const char *fmt, ...)
         ^
    100. {
    101.     int len = strlen(dst);

libavutil/avstring.c:101:5: 
     99. size_t av_strlcatf(char *dst, size_t size, const char *fmt, ...)
    100. {
    101.     int len = strlen(dst);
             ^
    102.     va_list vl;
    103. 

libavutil/avstring.c:104:5: 
    102.     va_list vl;
    103. 
    104.     va_start(vl, fmt);
             ^
    105.     len += vsnprintf(dst + len, size > len ? size - len : 0, fmt, vl);
    106.     va_end(vl);

libavutil/avstring.c:105:33: Condition is true
    103. 
    104.     va_start(vl, fmt);
    105.     len += vsnprintf(dst + len, size > len ? size - len : 0, fmt, vl);
                                         ^
    106.     va_end(vl);
    107. 

libavutil/avstring.c:105:5: 
    103. 
    104.     va_start(vl, fmt);
    105.     len += vsnprintf(dst + len, size > len ? size - len : 0, fmt, vl);
             ^
    106.     va_end(vl);
    107. 

libavutil/avstring.c:106:5: 
    104.     va_start(vl, fmt);
    105.     len += vsnprintf(dst + len, size > len ? size - len : 0, fmt, vl);
    106.     va_end(vl);
             ^
    107. 
    108.     return len;

libavutil/avstring.c:108:5: 
    106.     va_end(vl);
    107. 
    108.     return len;
             ^
    109. }
    110. 

libavutil/avstring.c:109:1: return from a call to av_strlcatf
    107. 
    108.     return len;
    109. }
         ^
    110. 
    111. char *av_d2str(double d)

libavformat/sdp.c:616:5: Skipping sdp_write_media_attributes(): empty list of specs
  614.     }
  615. 
  616.     sdp_write_media_attributes(buff, size, c, payload_type, fmt);
           ^
  617. }
  618. 

libavformat/sdp.c:617:1: return from a call to ff_sdp_write_media
  615. 
  616.     sdp_write_media_attributes(buff, size, c, payload_type, fmt);
  617. }
       ^
  618. 
  619. int av_sdp_create(AVFormatContext *ac[], int n_files, char *buf, int size)
