ffmpeg.c:3640: error: Null Dereference
  pointer `p` last assigned on line 3640 could be null and is dereferenced at line 3640, column 5.

ffmpeg.c:3625:1: start of procedure opt_streamid()
3623. 
3624. /* arg format is "output-stream-index:streamid-value". */
3625. static void opt_streamid(const char *opt, const char *arg)
      ^
3626. {
3627.     int idx;

ffmpeg.c:3631:5: 
3629.     char idx_str[16];
3630. 
3631.     strncpy(idx_str, arg, sizeof(idx_str));
          ^
3632.     idx_str[sizeof(idx_str)-1] = '\0';
3633.     p = strchr(idx_str, ':');

ffmpeg.c:3632:5: 
3630. 
3631.     strncpy(idx_str, arg, sizeof(idx_str));
3632.     idx_str[sizeof(idx_str)-1] = '\0';
          ^
3633.     p = strchr(idx_str, ':');
3634.     if (!p) {

ffmpeg.c:3633:5: 
3631.     strncpy(idx_str, arg, sizeof(idx_str));
3632.     idx_str[sizeof(idx_str)-1] = '\0';
3633.     p = strchr(idx_str, ':');
          ^
3634.     if (!p) {
3635.         fprintf(stderr,

ffmpeg.c:3634:10: Taking true branch
3632.     idx_str[sizeof(idx_str)-1] = '\0';
3633.     p = strchr(idx_str, ':');
3634.     if (!p) {
               ^
3635.         fprintf(stderr,
3636.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",

ffmpeg.c:3635:9: 
3633.     p = strchr(idx_str, ':');
3634.     if (!p) {
3635.         fprintf(stderr,
              ^
3636.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3637.                 arg, opt);

ffmpeg.c:3638:9: Skipping ffmpeg_exit(): empty list of specs
3636.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3637.                 arg, opt);
3638.         ffmpeg_exit(1);
              ^
3639.     }
3640.     *p++ = '\0';

ffmpeg.c:3640:5: 
3638.         ffmpeg_exit(1);
3639.     }
3640.     *p++ = '\0';
          ^
3641.     idx = parse_number_or_die(opt, idx_str, OPT_INT, 0, MAX_STREAMS-1);
3642.     streamid_map[idx] = parse_number_or_die(opt, p, OPT_INT, 0, INT_MAX);
