Five Rasberry Pi’s are used to drive this four-display video wall. This screenshot shows the system playing back some BBC documentaries. The sync, alignment, and video quality all seem to be spot on which makes it quite easy for your eye to assemble the images into one picture.
Each screen has its own Raspberry Pi which generates the HDMI video shown on the screen. These are fed from one central RPi board which acts as the controller. Video is pushed between the boards using the Real Time Streaming Protocol (RTSP) available through the Linux GStreamer package. Synchronization between the different video boards is taken care of using network time. [Samer] mentions that this system is scalable — each additional screen simply requires one more RPi to drive it.
The team also did some experiments with live video. They added a sixth RPi board with the camera module in order to display a live feed.