ffmpeg.c:3696: error: Null Dereference
  pointer `p` last assigned on line 3696 could be null and is dereferenced at line 3696, column 5.

ffmpeg.c:3681:1: start of procedure opt_streamid()
3679. 
3680. /* arg format is "output-stream-index:streamid-value". */
3681. static int opt_streamid(const char *opt, const char *arg)
      ^
3682. {
3683.     int idx;

ffmpeg.c:3687:5: 
3685.     char idx_str[16];
3686. 
3687.     strncpy(idx_str, arg, sizeof(idx_str));
          ^
3688.     idx_str[sizeof(idx_str)-1] = '\0';
3689.     p = strchr(idx_str, ':');

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

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

ffmpeg.c:3690:10: Taking true branch
3688.     idx_str[sizeof(idx_str)-1] = '\0';
3689.     p = strchr(idx_str, ':');
3690.     if (!p) {
               ^
3691.         fprintf(stderr,
3692.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",

ffmpeg.c:3691:9: 
3689.     p = strchr(idx_str, ':');
3690.     if (!p) {
3691.         fprintf(stderr,
              ^
3692.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3693.                 arg, opt);

ffmpeg.c:3694:9: Skipping ffmpeg_exit(): empty list of specs
3692.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3693.                 arg, opt);
3694.         ffmpeg_exit(1);
              ^
3695.     }
3696.     *p++ = '\0';

ffmpeg.c:3696:5: 
3694.         ffmpeg_exit(1);
3695.     }
3696.     *p++ = '\0';
          ^
3697.     idx = parse_number_or_die(opt, idx_str, OPT_INT, 0, MAX_STREAMS-1);
3698.     streamid_map = grow_array(streamid_map, sizeof(*streamid_map), &nb_streamid_map, idx+1);
