ffmpeg.c:3627: error: Null Dereference
  pointer `p` last assigned on line 3627 could be null and is dereferenced at line 3627, column 5.

ffmpeg.c:3612:1: start of procedure opt_streamid()
3610. 
3611. /* arg format is "output-stream-index:streamid-value". */
3612. static int opt_streamid(const char *opt, const char *arg)
      ^
3613. {
3614.     int idx;

ffmpeg.c:3618:5: 
3616.     char idx_str[16];
3617. 
3618.     strncpy(idx_str, arg, sizeof(idx_str));
          ^
3619.     idx_str[sizeof(idx_str)-1] = '\0';
3620.     p = strchr(idx_str, ':');

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

ffmpeg.c:3620:5: 
3618.     strncpy(idx_str, arg, sizeof(idx_str));
3619.     idx_str[sizeof(idx_str)-1] = '\0';
3620.     p = strchr(idx_str, ':');
          ^
3621.     if (!p) {
3622.         fprintf(stderr,

ffmpeg.c:3621:10: Taking true branch
3619.     idx_str[sizeof(idx_str)-1] = '\0';
3620.     p = strchr(idx_str, ':');
3621.     if (!p) {
               ^
3622.         fprintf(stderr,
3623.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",

ffmpeg.c:3622:9: 
3620.     p = strchr(idx_str, ':');
3621.     if (!p) {
3622.         fprintf(stderr,
              ^
3623.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3624.                 arg, opt);

ffmpeg.c:3625:9: Skipping ffmpeg_exit(): empty list of specs
3623.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3624.                 arg, opt);
3625.         ffmpeg_exit(1);
              ^
3626.     }
3627.     *p++ = '\0';

ffmpeg.c:3627:5: 
3625.         ffmpeg_exit(1);
3626.     }
3627.     *p++ = '\0';
          ^
3628.     idx = parse_number_or_die(opt, idx_str, OPT_INT, 0, MAX_STREAMS-1);
3629.     streamid_map = grow_array(streamid_map, sizeof(*streamid_map), &nb_streamid_map, idx+1);
