Is it possible to have the Pi take-in/capture footage then stream that footage over the network?
Could I also attach an IR receiver to one Pi, and have it repeat from an IR receiver on another Pi?
My hopes are to have the ability to capture the HDMI (or composite) from my Sky box and be able to watch what is being captured, in another room. At bit like the Sling Box.
You can't do this without external hardware - there are no models of Pi with an HDMI or composite input.
There's an interesting writeup at dwellertech.blogspot.co.uk which suggests that it might be plausible to use a Hauppauge pass-through interface. They used an HD PVR, which is now hard to find, in the article but it's reasonably likely that the HD PVR 2 or the HD PVR Rocket might work. There are some drivers on Hauppauge's support page, but I'm unsure as to their viability for Raspbian.
Basically:
The HDMI signal's duplicated to the interface's output port for the display. A copy is compressed to H.264 and output to the interface's USB socket. The interface appears to the Pi as a video device (/dev/video0), meaning that you should then be able to use a streaming package (VLC/FFmpeg/gstreamer/netcat/etc.) to transmit the stream to the network.
For the IR signals I'd suggest you look into lirc, and perhaps the python-lirc library. It should be entirely achievable to set up some infrared receivers and transmitters and shuttle the signals around your network.
