ffmpeg.c:3674: error: Null Dereference
  pointer `p` last assigned on line 3674 could be null and is dereferenced at line 3674, column 5.

ffmpeg.c:3659:1: start of procedure opt_streamid()
3657. 
3658. /* arg format is "output-stream-index:streamid-value". */
3659. static int opt_streamid(const char *opt, const char *arg)
      ^
3660. {
3661.     int idx;

ffmpeg.c:3665:5: 
3663.     char idx_str[16];
3664. 
3665.     strncpy(idx_str, arg, sizeof(idx_str));
          ^
3666.     idx_str[sizeof(idx_str)-1] = '\0';
3667.     p = strchr(idx_str, ':');

ffmpeg.c:3666:5: 
3664. 
3665.     strncpy(idx_str, arg, sizeof(idx_str));
3666.     idx_str[sizeof(idx_str)-1] = '\0';
          ^
3667.     p = strchr(idx_str, ':');
3668.     if (!p) {

ffmpeg.c:3667:5: 
3665.     strncpy(idx_str, arg, sizeof(idx_str));
3666.     idx_str[sizeof(idx_str)-1] = '\0';
3667.     p = strchr(idx_str, ':');
          ^
3668.     if (!p) {
3669.         fprintf(stderr,

ffmpeg.c:3668:10: Taking true branch
3666.     idx_str[sizeof(idx_str)-1] = '\0';
3667.     p = strchr(idx_str, ':');
3668.     if (!p) {
               ^
3669.         fprintf(stderr,
3670.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",

ffmpeg.c:3669:9: 
3667.     p = strchr(idx_str, ':');
3668.     if (!p) {
3669.         fprintf(stderr,
              ^
3670.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3671.                 arg, opt);

ffmpeg.c:3672:9: Skipping ffmpeg_exit(): empty list of specs
3670.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3671.                 arg, opt);
3672.         ffmpeg_exit(1);
              ^
3673.     }
3674.     *p++ = '\0';

ffmpeg.c:3674:5: 
3672.         ffmpeg_exit(1);
3673.     }
3674.     *p++ = '\0';
          ^
3675.     idx = parse_number_or_die(opt, idx_str, OPT_INT, 0, MAX_STREAMS-1);
3676.     streamid_map = grow_array(streamid_map, sizeof(*streamid_map), &nb_streamid_map, idx+1);
