ffmpeg.c:3653: error: Null Dereference
  pointer `p` last assigned on line 3653 could be null and is dereferenced at line 3653, column 5.

ffmpeg.c:3638:1: start of procedure opt_streamid()
3636. 
3637. /* arg format is "output-stream-index:streamid-value". */
3638. static void opt_streamid(const char *opt, const char *arg)
      ^
3639. {
3640.     int idx;

ffmpeg.c:3644:5: 
3642.     char idx_str[16];
3643. 
3644.     strncpy(idx_str, arg, sizeof(idx_str));
          ^
3645.     idx_str[sizeof(idx_str)-1] = '\0';
3646.     p = strchr(idx_str, ':');

ffmpeg.c:3645:5: 
3643. 
3644.     strncpy(idx_str, arg, sizeof(idx_str));
3645.     idx_str[sizeof(idx_str)-1] = '\0';
          ^
3646.     p = strchr(idx_str, ':');
3647.     if (!p) {

ffmpeg.c:3646:5: 
3644.     strncpy(idx_str, arg, sizeof(idx_str));
3645.     idx_str[sizeof(idx_str)-1] = '\0';
3646.     p = strchr(idx_str, ':');
          ^
3647.     if (!p) {
3648.         fprintf(stderr,

ffmpeg.c:3647:10: Taking true branch
3645.     idx_str[sizeof(idx_str)-1] = '\0';
3646.     p = strchr(idx_str, ':');
3647.     if (!p) {
               ^
3648.         fprintf(stderr,
3649.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",

ffmpeg.c:3648:9: 
3646.     p = strchr(idx_str, ':');
3647.     if (!p) {
3648.         fprintf(stderr,
              ^
3649.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3650.                 arg, opt);

ffmpeg.c:3651:9: Skipping ffmpeg_exit(): empty list of specs
3649.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3650.                 arg, opt);
3651.         ffmpeg_exit(1);
              ^
3652.     }
3653.     *p++ = '\0';

ffmpeg.c:3653:5: 
3651.         ffmpeg_exit(1);
3652.     }
3653.     *p++ = '\0';
          ^
3654.     idx = parse_number_or_die(opt, idx_str, OPT_INT, 0, MAX_STREAMS-1);
3655.     streamid_map[idx] = parse_number_or_die(opt, p, OPT_INT, 0, INT_MAX);
