ffmpeg.c:3541: error: Null Dereference
  pointer `p` last assigned on line 3541 could be null and is dereferenced at line 3541, column 5.

ffmpeg.c:3526:1: start of procedure opt_streamid()
3524. 
3525. /* arg format is "output-stream-index:streamid-value". */
3526. static int opt_streamid(const char *opt, const char *arg)
      ^
3527. {
3528.     int idx;

ffmpeg.c:3532:5: 
3530.     char idx_str[16];
3531. 
3532.     strncpy(idx_str, arg, sizeof(idx_str));
          ^
3533.     idx_str[sizeof(idx_str)-1] = '\0';
3534.     p = strchr(idx_str, ':');

ffmpeg.c:3533:5: 
3531. 
3532.     strncpy(idx_str, arg, sizeof(idx_str));
3533.     idx_str[sizeof(idx_str)-1] = '\0';
          ^
3534.     p = strchr(idx_str, ':');
3535.     if (!p) {

ffmpeg.c:3534:5: 
3532.     strncpy(idx_str, arg, sizeof(idx_str));
3533.     idx_str[sizeof(idx_str)-1] = '\0';
3534.     p = strchr(idx_str, ':');
          ^
3535.     if (!p) {
3536.         fprintf(stderr,

ffmpeg.c:3535:10: Taking true branch
3533.     idx_str[sizeof(idx_str)-1] = '\0';
3534.     p = strchr(idx_str, ':');
3535.     if (!p) {
               ^
3536.         fprintf(stderr,
3537.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",

ffmpeg.c:3536:9: 
3534.     p = strchr(idx_str, ':');
3535.     if (!p) {
3536.         fprintf(stderr,
              ^
3537.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3538.                 arg, opt);

ffmpeg.c:3539:9: Skipping ffmpeg_exit(): empty list of specs
3537.                 "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
3538.                 arg, opt);
3539.         ffmpeg_exit(1);
              ^
3540.     }
3541.     *p++ = '\0';

ffmpeg.c:3541:5: 
3539.         ffmpeg_exit(1);
3540.     }
3541.     *p++ = '\0';
          ^
3542.     idx = parse_number_or_die(opt, idx_str, OPT_INT, 0, MAX_STREAMS-1);
3543.     streamid_map = grow_array(streamid_map, sizeof(*streamid_map), &nb_streamid_map, idx+1);
