libavformat/utils.c:2578: error: Null Dereference
  pointer `pb` last assigned on line 2565 could be null and is dereferenced by call to `avio_close()` at line 2578, column 5.

libavformat/utils.c:2558:1: start of procedure avformat_close_input()
2556. }
2557. 
2558. void avformat_close_input(AVFormatContext **ps)
      ^
2559. {
2560.     AVFormatContext *s = *ps;

libavformat/utils.c:2560:5: 
2558. void avformat_close_input(AVFormatContext **ps)
2559. {
2560.     AVFormatContext *s = *ps;
          ^
2561.     AVIOContext *pb = s->pb;
2562. 

libavformat/utils.c:2561:5: 
2559. {
2560.     AVFormatContext *s = *ps;
2561.     AVIOContext *pb = s->pb;
          ^
2562. 
2563.     if ((s->iformat && s->iformat->flags & AVFMT_NOFILE) ||

libavformat/utils.c:2563:10: Taking true branch
2561.     AVIOContext *pb = s->pb;
2562. 
2563.     if ((s->iformat && s->iformat->flags & AVFMT_NOFILE) ||
               ^
2564.         (s->flags & AVFMT_FLAG_CUSTOM_IO))
2565.         pb = NULL;

libavformat/utils.c:2563:24: Taking false branch
2561.     AVIOContext *pb = s->pb;
2562. 
2563.     if ((s->iformat && s->iformat->flags & AVFMT_NOFILE) ||
                             ^
2564.         (s->flags & AVFMT_FLAG_CUSTOM_IO))
2565.         pb = NULL;

libavformat/utils.c:2564:10: Taking true branch
2562. 
2563.     if ((s->iformat && s->iformat->flags & AVFMT_NOFILE) ||
2564.         (s->flags & AVFMT_FLAG_CUSTOM_IO))
               ^
2565.         pb = NULL;
2566. 

libavformat/utils.c:2565:9: 
2563.     if ((s->iformat && s->iformat->flags & AVFMT_NOFILE) ||
2564.         (s->flags & AVFMT_FLAG_CUSTOM_IO))
2565.         pb = NULL;
              ^
2566. 
2567.     flush_packet_queue(s);

libavformat/utils.c:2567:5: Skipping flush_packet_queue(): empty list of specs
2565.         pb = NULL;
2566. 
2567.     flush_packet_queue(s);
          ^
2568. 
2569.     if (s->iformat) {

libavformat/utils.c:2569:9: Taking true branch
2567.     flush_packet_queue(s);
2568. 
2569.     if (s->iformat) {
              ^
2570.         if (s->iformat->read_close)
2571.             s->iformat->read_close(s);

libavformat/utils.c:2570:13: Taking true branch
2568. 
2569.     if (s->iformat) {
2570.         if (s->iformat->read_close)
                  ^
2571.             s->iformat->read_close(s);
2572.     }

libavformat/utils.c:2571:13: Skipping __function_pointer__(): unresolved function pointer
2569.     if (s->iformat) {
2570.         if (s->iformat->read_close)
2571.             s->iformat->read_close(s);
                  ^
2572.     }
2573. 

libavformat/utils.c:2574:5: Skipping avformat_free_context(): empty list of specs
2572.     }
2573. 
2574.     avformat_free_context(s);
          ^
2575. 
2576.     *ps = NULL;

libavformat/utils.c:2576:5: 
2574.     avformat_free_context(s);
2575. 
2576.     *ps = NULL;
          ^
2577. 
2578.     avio_close(pb);

libavformat/utils.c:2578:5: 
2576.     *ps = NULL;
2577. 
2578.     avio_close(pb);
          ^
2579. }
2580. 

libavformat/aviobuf.c:794:1: start of procedure avio_close()
  792. }
  793. 
  794. int avio_close(AVIOContext *s)
       ^
  795. {
  796.     URLContext *h;

libavformat/aviobuf.c:798:10: Taking false branch
  796.     URLContext *h;
  797. 
  798.     if (!s)
                ^
  799.         return 0;
  800. 

libavformat/aviobuf.c:801:5: 
  799.         return 0;
  800. 
  801.     avio_flush(s);
           ^
  802.     h = s->opaque;
  803.     av_freep(&s->buffer);

libavformat/aviobuf.c:180:1: start of procedure avio_flush()
    178. }
    179. 
    180. void avio_flush(AVIOContext *s)
         ^
    181. {
    182.     flush_buffer(s);

libavformat/aviobuf.c:182:5: 
    180. void avio_flush(AVIOContext *s)
    181. {
    182.     flush_buffer(s);
             ^
    183.     s->must_flush = 0;
    184. }

libavformat/aviobuf.c:124:1: start of procedure flush_buffer()
      122. }
      123. 
      124. static void flush_buffer(AVIOContext *s)
           ^
      125. {
      126.     if (s->buf_ptr > s->buffer) {

libavformat/aviobuf.c:126:9: 
      124. static void flush_buffer(AVIOContext *s)
      125. {
      126.     if (s->buf_ptr > s->buffer) {
                   ^
      127.         if (s->write_packet && !s->error) {
      128.             int ret = s->write_packet(s->opaque, s->buffer,
