CasparCG is the software run on ystvvidsrv to play out non-live shows onto the live channel, as directed by the Scheduling system. It was written by SVT (Sweden's public broadcaster) and made open-source, available from their website.
The CasparCG server allows a series of media layers (producers), containing still images, videos and Flash-based graphics to be composited in real-time and output to any number of video consumers, such as the screen, a file or Blackmagic/Bluefish SDI output cards. See their wiki for more information.
How we use it
On the video server, CasparCG is configured to play out to the screen, using the S-Video output of the graphics card which has been set up to generate PAL video. See instructions in Computing:How To set up Windows TV out. A converter cable is used to turn this into composite video, which is injected into the vision path, while audio is a line out from the sound card into the audio path.
The scheduler can play video from the playout directory on its local D: drive (which is automatically populated by the encoder) or use the Flash graphics to render station identification bugs and continuity graphics over the live output, using a series of templates on the D: drive of the video server.
Control of CasparCG uses a simple text-based protocol on port 5250, which is documented at http://casparcg.com/wiki/CasparCG_2.0_AMCP_Protocol. To mitigate the security risk of opening playout control up to the whole University, the server's firewall is restricted to only allow access from a handful of YSTV machines, so remote access must be tunnelled through the webserver using SSH tunneling.
Remote access is impossible without disabling video output to the vision path or potentially crippling the output resolution settings, and shouldn't be used unless absolutely necessary. Instead, a second monitor should be connected to the VGA output (possibly via a KVM) and a local terminal used instead. Ideally, CasparCG should be set to run full-screen on the secondary monitor, which is the TV-out, while the primary is the admin console, however this means the VGA monitor can never be unplugged (not a problem with a KVM).
CasparCG is configured in an XML file next to the casparcg.exe executable.