Thanks, Robert! It seems it should work. ( not tested yet ). Checking signal strength is not the right way, cause it is strength of TV signal. If I am not right please correct me. Regards, Dmitry. RD> I'm assuming you're using the stable bttv driver (v0.7.8) under 2.4. RD> The Imagenation PXC200 seems to have ADC disabled by default. RD> Try: RD> insmod bttv card=29 RD> If that doesn't kill your card and if it works add the snipped of code RD> from bttv-cards.c init_PXC200() to you cards init code (default?): RD> btwrite(BT848_ADC_RESERVED|BT848_ADC__AGC_EN,BT848_ADC); RD> The bttv driver has support for signal strength detection, which can be RD> used to detect the presence of cameras. Maybe you could just disable the RD> dead cameras? RD> //assuming /dev/video device is opened RD> struct video_tuner vt; RD> ioctl(video_dev_fd,VIDIOCGTUNER,&vt); RD> printf("Signal Strength = [%d]\n",vt.signal); RD> Cheers, RD> Robert. RD> Dmitry Alexeyev wrote: >> >> Hello. >> >> I have BT878 card and external multiplexer with several monochrome cameras >> connected to it. If one camera is off ( blank screen ), bt878 >> automaticaly increases brightness, so I can see nothing on frames from >> other cameras. >> How can i turn off AGC ? >> >> Dmitry >> >> _______________________________________________ >> Video4linux-list mailing list >> Video4linux-list@xxxxxxxxxx >> https://listman.redhat.com/mailman/listinfo/video4linux-list RD> _______________________________________________ RD> Video4linux-list mailing list RD> Video4linux-list@xxxxxxxxxx RD> https://listman.redhat.com/mailman/listinfo/video4linux-list -- С уважением, Dmitry mailto:D.Alexeyev@xxxxxxxxxx