I'd like to create an app that pulls multiple live video feeds, supplied either by coax, hdmi or some other standard, into WPF for manipulation (i.e. apply a few transforms or pixel shaders) which is then output to monitor. What would I look at to get started with this app - is there any hardware that would make things easier?
If you are pulling in standard broadcast via coax or over the air, a $100 ATSC HD TV tuner will do. I don't have any experience with HD capture cards (I think they run for about $1000), or more specifically, cards that take in a raw HD stream.
When you install a capture device (TV tuner, webcam, capture card) in Windows, it creates a DirectShow source filter wrapper for it. Based off what kind of hw you are targeting, determines how you create the DirectShow graph. I have no reason to expect HD capture cards to be different than any capture card or webcam (TV tuners are slightly different).
You can use my WPF MediaKit as a base. The web cam control may work out of the box or just require slight changes for an HD capture card. A TV tuner would require a lot more than just this.