I want to stream a video call similar to skype (but it doesnt necessarily have to be skype) to a rasberry pi for output to a monitor. Is this possible?
If you have a Nvidea Gamestream supported GPU this can be done with better performance over VNC.
Moonlight is the opensource clone of Nvidea's shield technologie. It works rather well and can stream sound and video to client devices.
Instead of streaming traditional Steam client or games, you use the remote desktop exe on a windows host for example, als a source application.
Yes, have a look at UV4L. It allows you to stream audio & video.
In the case that you're trying to restream a video call I'd consider using VLC on both the machine receiving the call and the receiving Pi. The instructions at the link show how it can be configured to stream the entire desktop of one machine to another: https://software.grok.lsu.edu/article.aspx?articleid=14625
On the sending side you set your desktop as the capture source for VLC, then set an IP address for that source to be streamed to. Adjust your audio and video transcoding options to meet the requirements of your streaming capacity (higher quality/high bandwidth, low quality/lower bandwidth).
On the receiving side, you just open the network stream matching the configuration set on the sending side.
Ideally you would create a couple of scripts for both the sending and receiving sides which would run VLC and set up the necessary session parameters at each end. I would use a script on the sending side which accessed the Pi over SSH to run its VLC script. There are some options outlined here which should help: http://dtucker.co.uk/hack/ssh-for-python-in-search-of-api-perfection.html .