mpa

int subscribe(char * sub_name, char * client_name)
{
    printf("connecting to camera pipe %s\r\n",sub_name);

    if(pipe_expand_location_string(sub_name, pipe_name)<0){
        fprintf(stderr, "ERROR: Invalid pipe name: %s\n", sub_name);
        exit(-1);
    }

    int ch      = pipe_client_get_next_available_channel();
    int buf_len = 0;
    pipe_client_set_camera_helper_cb(ch, _helper_cb, NULL);
    pipe_client_open(ch, pipe_name, client_name, EN_PIPE_CLIENT_CAMERA_HELPER, buf_len);

    printf("subscribed to camera pipe %s, channel %d\r\n",pipe_name, ch);

    sub_ch = ch;

    return ch;
}