ffmpeg.c:3545: error: Null Dereference
  pointer `p` last assigned on line 3545 could be null and is dereferenced at line 3545, column 5.

ffmpeg.c:3530:1: start of procedure opt_streamid()
3528. 
3529. /* arg format is "output-stream-index:streamid-value". */
3530. static int opt_streamid(const char *opt, const char *arg)
      ^
3531. {
3532.     int idx;

ffmpeg.c:3536:5: 
3534.     char idx_str[16];
3535. 
3536.     strncpy(idx_str, arg, sizeof(idx_str));
          ^
3537.     idx_str[sizeof(idx_str)-1] = '\0';
3538.     p = strchr(idx_str, ':');

ffmpeg.c:3537:5: 
3535. 
3536.     strncpy(idx_str, arg, sizeof(idx_str));
3537.     idx_str[sizeof(idx_str)-1] = '\0';
          ^
3538.     p = strchr(idx_str, ':');
3539.     if (!p) {

ffmpeg.c:3538:5: 
3536.     strncpy(idx_str, arg, sizeof(idx_str));
3537.     idx_str[sizeof(idx_str)-1] = '\0';
3538.     p = strchr(idx_str, ':');
          ^
3539.     if (!p) {
3540.         fprintf(stderr,

ffmpeg.c:3539:10: Taking true branch
3537.     idx_str[sizeof(idx_str)-1] = '\0';
3538.     p = strchr(idx_str, ':');
3539.     if (!p) {
               ^
3540.         fprintf(stderr,
3541.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",

ffmpeg.c:3540:9: 
3538.     p = strchr(idx_str, ':');
3539.     if (!p) {
3540.         fprintf(stderr,
              ^
3541.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3542.                 arg, opt);

ffmpeg.c:3543:9: Skipping ffmpeg_exit(): empty list of specs
3541.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3542.                 arg, opt);
3543.         ffmpeg_exit(1);
              ^
3544.     }
3545.     *p++ = '\0';

ffmpeg.c:3545:5: 
3543.         ffmpeg_exit(1);
3544.     }
3545.     *p++ = '\0';
          ^
3546.     idx = parse_number_or_die(opt, idx_str, OPT_INT, 0, MAX_STREAMS-1);
3547.     streamid_map = grow_array(streamid_map, sizeof(*streamid_map), &nb_streamid_map, idx+1);
