c - libvlc_media_get_duration always returns 0 -

i'm writing media player in pure c , i'm using libvlc. i'm developing media library , i'm writing directory walker , media file parser. works pretty fine various metadata artists or albums, etc., libvlc_media_get_duration returns 0. tried , searched everywhere, can't make work. can me?

here code:

#include <stdlib.h> #include <stdio.h> #include <string.h> #include <vlc/vlc.h> #include <stdarg.h> #include <stdbool.h> #include <dirent.h> #include <sys/stat.h>  void strcopy(char **dst, const char *src) {   unsigned int size = strlen(src);   *dst = (char *) realloc(*dst, sizeof(char) * (size + 1));   strncpy(*dst, src, size);   *(*dst+size) = 0; }  void strconcat(char **dst, int n, ...) {    va_list args;   unsigned int count = 0;    // count   va_start(args, n);   (unsigned short = 0; < n; i++)     count += strlen(va_arg(args, char*));   va_end(args);    // allocate   *dst = (char *) realloc(*dst, sizeof(char) * (count+1));   unsigned int cursor = 0;   va_start(args, n);   for(unsigned short = 0; < n; i++) {     char *src = va_arg(args, char*);     strncpy((*dst+cursor), src, strlen(src));     cursor += strlen(src);     *(*dst+cursor) = 0;   }   va_end(args);  }  void /* process tags , add file database */ __db_add_file(libvlc_instance_t *inst, const char *url, bool compute_hash) {    // create new media   libvlc_media_t *media = libvlc_media_new_path(inst, url);   libvlc_media_parse(media);    if (libvlc_media_is_parsed(media)) {      printf("%s\n", url);     printf("%llu\n", libvlc_media_get_duration(media));   }    libvlc_media_release(media);  }  void /* walker on directory */ __db_dir_walker(libvlc_instance_t *inst, const char *dir_url, bool compute_hash) {    // build base path   char *base_url = null;   if (dir_url[strlen(dir_url)-1] != '/')     strconcat(&base_url, 2, dir_url, "/");   else     strcopy(&base_url, dir_url);    // create necessary variables   struct dirent *entry;   dir *dir;   struct stat fs;    // try open dir   if (!(dir = opendir(dir_url))) return;    while (entry = readdir(dir)) {      // strip parent entries     if ((strcmp(".", entry->d_name) == 0) ||         (strcmp("..", entry->d_name) == 0)) continue;      char *dir_full_path = null;     strconcat(&dir_full_path, 2, base_url, entry->d_name);      if (stat(dir_full_path, &fs) < 0) return;      if (s_isdir(fs.st_mode)) { // process directory        __db_dir_walker(inst, dir_full_path, compute_hash);      } else { // process media file        __db_add_file(inst, dir_full_path, compute_hash);     }    }    // free memory   closedir(dir); }  void db_scan_directory(const char *dir_url, bool compute_hash) {    // try open target dir   if (!opendir(dir_url)) return;    // preload vlc instance tag data retrieving   libvlc_instance_t *inst = libvlc_new(0, null);    // walk on directory   __db_dir_walker(inst, dir_url, compute_hash);    // free resources   libvlc_release(inst); }  int main () {    db_scan_directory("/media/storage/music/blur/", false);    return 0; } 

thank you!

if there wants know answer on question too, here is:

you need play duration.

thanks jean-baptiste kempf videolan forums.