For those of you with amateur radio licences, here is a moderately complex RPi project which enables you to transmit Digital Amateur Television (ATV) to other radio amateurs from your Raspberry Pi.
The Portsdown Digital Amateur Television transmitter has been designed by a team of British Amateur TV Club (BATC) members and has been promoted by the BATC to provide an easy, low-cost entry to home-built digital TV transmission.
The basic unit uses a Raspberry Pi, a Raspberry Pi camera, a local oscillator and a filter-modulator board to produce 10 mW of digital ATV on 146, 437 or 1255 MHz. All these items except the filter-modulator board are readily available from internet suppliers. The filter-modulator board can either be home-constructed or purchased ready-made and tested from the BATC.
Supported enhancements to the transmitter include a touchscreen to allow easy control, a video capture device to allow the use of analogue video cameras, a sound input USB dongle, multiple switched RF and PTT outputs, and an RTL-SDR dongle to add a basic receive capability.
Full construction details are on this Wiki https://wiki.batc.tv/The_Portsdown_Transmitter and the software is here with full build instructions https://github.com/BritishAmateurTelevisionClub/rpidatv. There is an active discussion forum here http://batc.org.uk/forum/viewforum.php?f=103
Even if you don't build the complete project you may find the composite video capture and streaming capabilities useful