strstart(filename, "file:", &filename);
static int file_open(URLContext *h, const char *filename, int flags){    int access;    int fd;    if (flags & URL_WRONLY) {        access = O_CREAT | O_TRUNC | O_WRONLY;    } else {        access = O_RDONLY;    }#ifdef CONFIG_WIN32    access |= O_BINARY;#endif    fd = open(filename, access, 0666);    if (fd < 0)        return -ENOENT;    h->priv_data = (void *)fd;    return 0;}