t_vol
t_vol.vol[0] = l_volctrl.channel0;
t_vol.vol[1] = l_volctrl.channel1;
t_vol.vol[2] = l_volctrl.channel2;
t_vol.vol[3] = l_volctrl.channel3;
error = ioctlf(fp, CDIOCSETVOL, &t_vol);
error = ioctlf(fp, CDIOCGETVOL, &t_vol);
l_volctrl.channel0 = t_vol.vol[0];
l_volctrl.channel1 = t_vol.vol[1];
l_volctrl.channel2 = t_vol.vol[2];
l_volctrl.channel3 = t_vol.vol[3];