UVC_N_TRANSFER
for (i = 0; i < UVC_N_TRANSFER; i++)
video->data->xfer, uvc_config, UVC_N_TRANSFER, sc, &video->mtx);
for (i = 0; i < UVC_N_TRANSFER; i++)
usbd_transfer_unsetup(video->data->xfer, UVC_N_TRANSFER);
usbd_transfer_unsetup(v->data->xfer, UVC_N_TRANSFER);