Does anyone know how an On Screen Display works? For example, comcast digital cable. How are text, menus, and graphics displayed and overlayed? What type of electronics are needed to do this?
Does anyone know how an On Screen Display works? For example, comcast digital cable. How are text, menus, and graphics displayed and overlayed? What type of electronics are needed to do this?
It's normally done with a "genlock", a device which syncronises the two video streams and combines and overlays them. In professional TV production it's even easier (or at least was!), all cameras and equipment were syncronised to a common sync source, so you could use fairly simple video mixers to do it.
If you just want to add an On Screen Display?, there are various OSB chips manufactured, specifically to put text on video signals - most TV's, VCR's and Satellite Receivers use them.
The **broken link removed**
was my favourite, but like all OSD chips, no longer manufactured.
So if you want one you'll need to find it from someone who has it still stocked.
If Nigel knows a current OSD chip that is still manufactured I would like to know too
I designed an OSD board around an NEC chip a number of years ago, and Dontronics was going to produce a board for it, but NEC discontinued the chip. The replacement chip was different, and I was never able to get even a sample of it :cry: