redger Amlogic H/W decoder has issues with decoding SD MPEG2 videos. There *might* be an improvement in Krypton, we'll see.Regarding custom EDID - currently there's no way to achieve that but you may want to take a look into something doing similar thing: disp_cap_hack
Thanks kszaq,
The fix for the interlaced material was easy .... just deinterlace in software for low resolutions (<720) and hardware for high res.
The screen interactions seem to be working properly now and I may have mis-diagnosed the problem. It looks more like a hot-plug issues ie. all works well if the screen is attached at boot time, not so good if I unplug / change screens.
Thanks again