ffmpeg.c:3626: error: Null Dereference
  pointer `p` last assigned on line 3626 could be null and is dereferenced at line 3626, column 5.

ffmpeg.c:3611:1: start of procedure opt_streamid()
3609. 
3610. /* arg format is "output-stream-index:streamid-value". */
3611. static int opt_streamid(const char *opt, const char *arg)
      ^
3612. {
3613.     int idx;

ffmpeg.c:3617:5: 
3615.     char idx_str[16];
3616. 
3617.     strncpy(idx_str, arg, sizeof(idx_str));
          ^
3618.     idx_str[sizeof(idx_str)-1] = '\0';
3619.     p = strchr(idx_str, ':');

ffmpeg.c:3618:5: 
3616. 
3617.     strncpy(idx_str, arg, sizeof(idx_str));
3618.     idx_str[sizeof(idx_str)-1] = '\0';
          ^
3619.     p = strchr(idx_str, ':');
3620.     if (!p) {

ffmpeg.c:3619:5: 
3617.     strncpy(idx_str, arg, sizeof(idx_str));
3618.     idx_str[sizeof(idx_str)-1] = '\0';
3619.     p = strchr(idx_str, ':');
          ^
3620.     if (!p) {
3621.         fprintf(stderr,

ffmpeg.c:3620:10: Taking true branch
3618.     idx_str[sizeof(idx_str)-1] = '\0';
3619.     p = strchr(idx_str, ':');
3620.     if (!p) {
               ^
3621.         fprintf(stderr,
3622.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",

ffmpeg.c:3621:9: 
3619.     p = strchr(idx_str, ':');
3620.     if (!p) {
3621.         fprintf(stderr,
              ^
3622.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3623.                 arg, opt);

ffmpeg.c:3624:9: Skipping ffmpeg_exit(): empty list of specs
3622.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3623.                 arg, opt);
3624.         ffmpeg_exit(1);
              ^
3625.     }
3626.     *p++ = '\0';

ffmpeg.c:3626:5: 
3624.         ffmpeg_exit(1);
3625.     }
3626.     *p++ = '\0';
          ^
3627.     idx = parse_number_or_die(opt, idx_str, OPT_INT, 0, MAX_STREAMS-1);
3628.     streamid_map = grow_array(streamid_map, sizeof(*streamid_map), &nb_streamid_map, idx+1);
