V4L2_CID_BASE
if (ctrl_id < V4L2_CID_BASE) {
idx = ctrl_id - V4L2_CID_BASE;
#define V4L2_CID_USER_BASE V4L2_CID_BASE
#define V4L2_CID_BRIGHTNESS (V4L2_CID_BASE+0)
#define V4L2_CID_CONTRAST (V4L2_CID_BASE+1)
#define V4L2_CID_SATURATION (V4L2_CID_BASE+2)
#define V4L2_CID_HUE (V4L2_CID_BASE+3)
#define V4L2_CID_AUDIO_VOLUME (V4L2_CID_BASE+5)
#define V4L2_CID_AUDIO_BALANCE (V4L2_CID_BASE+6)
#define V4L2_CID_AUDIO_BASS (V4L2_CID_BASE+7)
#define V4L2_CID_AUDIO_TREBLE (V4L2_CID_BASE+8)
#define V4L2_CID_AUDIO_MUTE (V4L2_CID_BASE+9)
#define V4L2_CID_AUDIO_LOUDNESS (V4L2_CID_BASE+10)
#define V4L2_CID_BLACK_LEVEL (V4L2_CID_BASE+11)
#define V4L2_CID_AUTO_WHITE_BALANCE (V4L2_CID_BASE+12)
#define V4L2_CID_DO_WHITE_BALANCE (V4L2_CID_BASE+13)
#define V4L2_CID_RED_BALANCE (V4L2_CID_BASE+14)
#define V4L2_CID_BLUE_BALANCE (V4L2_CID_BASE+15)
#define V4L2_CID_GAMMA (V4L2_CID_BASE+16)
#define V4L2_CID_EXPOSURE (V4L2_CID_BASE+17)
#define V4L2_CID_AUTOGAIN (V4L2_CID_BASE+18)
#define V4L2_CID_GAIN (V4L2_CID_BASE+19)
#define V4L2_CID_HFLIP (V4L2_CID_BASE+20)
#define V4L2_CID_VFLIP (V4L2_CID_BASE+21)
#define V4L2_CID_HCENTER (V4L2_CID_BASE+22)
#define V4L2_CID_VCENTER (V4L2_CID_BASE+23)
#define V4L2_CID_LASTP1 (V4L2_CID_BASE+24) /* last CID + 1 */