mc maddie

Analog NTSC video on i.MX6

Discussion created by mc maddie on May 5, 2019
Latest reply on May 16, 2019 by mc maddie

We have custom HW with i.MX6Q and Intersil TW9990 analog video decoder. It works fine with the PAL camera and I can see stable video image as expected.


That decoder chip also supports other format, NTSC included. 


I've now been trying to get NTSC video working and it's working 'almost'. And by 'almost' I mean that I have picture, but it's not synchronized ie it's rolling from down to up and I can see some screen wide green blocks there rolling with them. I suspect that is when the actual 'sync' is happening between frames. It also seems that interlaced frames are bit out of sync too so image rolls between frames. I'm using Analog NTSC - camera as video signal source.


When reading the TW9990 status registers it says that format is NTSC_M and that video is locked and what I can tell the decoder thinks everything is good. Of course it still can be decoder problem since I'd assume there wouldn't be any picture if i.MX6 side wasn't configured properly?


Has anyone played with NTSC video and/or have any good pointers what to check? I running low on ideas. I have tried different configurations on TW9990 end, but they've made no changes. Also I'm not really expert on Video4Linux I'm using for testing the video.