ffmpeg.c:3676: error: Null Dereference
  pointer `p` last assigned on line 3676 could be null and is dereferenced at line 3676, column 5.

ffmpeg.c:3661:1: start of procedure opt_streamid()
3659. 
3660. /* arg format is "output-stream-index:streamid-value". */
3661. static int opt_streamid(const char *opt, const char *arg)
      ^
3662. {
3663.     int idx;

ffmpeg.c:3667:5: 
3665.     char idx_str[16];
3666. 
3667.     strncpy(idx_str, arg, sizeof(idx_str));
          ^
3668.     idx_str[sizeof(idx_str)-1] = '\0';
3669.     p = strchr(idx_str, ':');

ffmpeg.c:3668:5: 
3666. 
3667.     strncpy(idx_str, arg, sizeof(idx_str));
3668.     idx_str[sizeof(idx_str)-1] = '\0';
          ^
3669.     p = strchr(idx_str, ':');
3670.     if (!p) {

ffmpeg.c:3669:5: 
3667.     strncpy(idx_str, arg, sizeof(idx_str));
3668.     idx_str[sizeof(idx_str)-1] = '\0';
3669.     p = strchr(idx_str, ':');
          ^
3670.     if (!p) {
3671.         fprintf(stderr,

ffmpeg.c:3670:10: Taking true branch
3668.     idx_str[sizeof(idx_str)-1] = '\0';
3669.     p = strchr(idx_str, ':');
3670.     if (!p) {
               ^
3671.         fprintf(stderr,
3672.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",

ffmpeg.c:3671:9: 
3669.     p = strchr(idx_str, ':');
3670.     if (!p) {
3671.         fprintf(stderr,
              ^
3672.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3673.                 arg, opt);

ffmpeg.c:3674:9: Skipping ffmpeg_exit(): empty list of specs
3672.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3673.                 arg, opt);
3674.         ffmpeg_exit(1);
              ^
3675.     }
3676.     *p++ = '\0';

ffmpeg.c:3676:5: 
3674.         ffmpeg_exit(1);
3675.     }
3676.     *p++ = '\0';
          ^
3677.     idx = parse_number_or_die(opt, idx_str, OPT_INT, 0, MAX_STREAMS-1);
3678.     streamid_map = grow_array(streamid_map, sizeof(*streamid_map), &nb_streamid_map, idx+1);
