ffmpeg.c:3656: error: Null Dereference
  pointer `p` last assigned on line 3656 could be null and is dereferenced at line 3656, column 5.

ffmpeg.c:3641:1: start of procedure opt_streamid()
3639. 
3640. /* arg format is "output-stream-index:streamid-value". */
3641. static int opt_streamid(const char *opt, const char *arg)
      ^
3642. {
3643.     int idx;

ffmpeg.c:3647:5: 
3645.     char idx_str[16];
3646. 
3647.     strncpy(idx_str, arg, sizeof(idx_str));
          ^
3648.     idx_str[sizeof(idx_str)-1] = '\0';
3649.     p = strchr(idx_str, ':');

ffmpeg.c:3648:5: 
3646. 
3647.     strncpy(idx_str, arg, sizeof(idx_str));
3648.     idx_str[sizeof(idx_str)-1] = '\0';
          ^
3649.     p = strchr(idx_str, ':');
3650.     if (!p) {

ffmpeg.c:3649:5: 
3647.     strncpy(idx_str, arg, sizeof(idx_str));
3648.     idx_str[sizeof(idx_str)-1] = '\0';
3649.     p = strchr(idx_str, ':');
          ^
3650.     if (!p) {
3651.         fprintf(stderr,

ffmpeg.c:3650:10: Taking true branch
3648.     idx_str[sizeof(idx_str)-1] = '\0';
3649.     p = strchr(idx_str, ':');
3650.     if (!p) {
               ^
3651.         fprintf(stderr,
3652.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",

ffmpeg.c:3651:9: 
3649.     p = strchr(idx_str, ':');
3650.     if (!p) {
3651.         fprintf(stderr,
              ^
3652.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3653.                 arg, opt);

ffmpeg.c:3654:9: Skipping ffmpeg_exit(): empty list of specs
3652.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3653.                 arg, opt);
3654.         ffmpeg_exit(1);
              ^
3655.     }
3656.     *p++ = '\0';

ffmpeg.c:3656:5: 
3654.         ffmpeg_exit(1);
3655.     }
3656.     *p++ = '\0';
          ^
3657.     idx = parse_number_or_die(opt, idx_str, OPT_INT, 0, MAX_STREAMS-1);
3658.     streamid_map = grow_array(streamid_map, sizeof(*streamid_map), &nb_streamid_map, idx+1);
