ffmpeg.c:3697: error: Null Dereference
  pointer `p` last assigned on line 3697 could be null and is dereferenced at line 3697, column 5.

ffmpeg.c:3682:1: start of procedure opt_streamid()
3680. 
3681. /* arg format is "output-stream-index:streamid-value". */
3682. static int opt_streamid(const char *opt, const char *arg)
      ^
3683. {
3684.     int idx;

ffmpeg.c:3688:5: 
3686.     char idx_str[16];
3687. 
3688.     strncpy(idx_str, arg, sizeof(idx_str));
          ^
3689.     idx_str[sizeof(idx_str)-1] = '\0';
3690.     p = strchr(idx_str, ':');

ffmpeg.c:3689:5: 
3687. 
3688.     strncpy(idx_str, arg, sizeof(idx_str));
3689.     idx_str[sizeof(idx_str)-1] = '\0';
          ^
3690.     p = strchr(idx_str, ':');
3691.     if (!p) {

ffmpeg.c:3690:5: 
3688.     strncpy(idx_str, arg, sizeof(idx_str));
3689.     idx_str[sizeof(idx_str)-1] = '\0';
3690.     p = strchr(idx_str, ':');
          ^
3691.     if (!p) {
3692.         fprintf(stderr,

ffmpeg.c:3691:10: Taking true branch
3689.     idx_str[sizeof(idx_str)-1] = '\0';
3690.     p = strchr(idx_str, ':');
3691.     if (!p) {
               ^
3692.         fprintf(stderr,
3693.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",

ffmpeg.c:3692:9: 
3690.     p = strchr(idx_str, ':');
3691.     if (!p) {
3692.         fprintf(stderr,
              ^
3693.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3694.                 arg, opt);

ffmpeg.c:3695:9: Skipping ffmpeg_exit(): empty list of specs
3693.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3694.                 arg, opt);
3695.         ffmpeg_exit(1);
              ^
3696.     }
3697.     *p++ = '\0';

ffmpeg.c:3697:5: 
3695.         ffmpeg_exit(1);
3696.     }
3697.     *p++ = '\0';
          ^
3698.     idx = parse_number_or_die(opt, idx_str, OPT_INT, 0, MAX_STREAMS-1);
3699.     streamid_map = grow_array(streamid_map, sizeof(*streamid_map), &nb_streamid_map, idx+1);
