Live streaming video on website?

Here is a question I hope someone can answer for me? I was wanting to know if it is possible to stream live video from my computer/tv/pc to a website I'm building. For example, I have my video running from external source (e.g. cable,dvd player,pc media player) and it's running into a tuner card on my desktop. I want to essentially perform a live webcast and stream it live for visitors to view. What would be needed to perform this? Any HTML junkies know the source code for that? Any help is appreciated!