I am passionate about foosball so during the Christmas of 2008 I decided to build an automatic slow motion replay system for training purposes. The heart of the system is the Casio EX-F1 high speed camera and the Texas Instruments eZ430-RF2500 wireless development kit. Read on if you are interested in the technical details of the system.
The EX-F1 shoots high speed video right out of the box, but for some reason Casio did not provide a way to trigger the movie recording externally. I came up with the solution to rewire the hot shoe adapter so that it could trigger the movie record button. In June 2009 Casio released a new firmware that supports tethered shooting so hopefully I can use that instead (after a little bit of USB reverse engineering of course).
The purpose of the eZ430-RF2500 kit is in one end to monitor an accelerometer mounted behind one of the goals and in the other end to trigger the camera. I guess you could call it a wireless camera trigger. The accelerometer goal detection scheme works fairly well after a bit of fine tuning of the sensitivity.
After a goal is scored, raw slow motion video is automatically transferred from the camera to a PC using an Eye-Fi Explore Video SD card. Raw slow motion video is not that exiting, so I wrote a script that monitors the incoming videos, speeds up the boring parts and adds a bit of text (as shown in the video above). The video processing is done using Avisynth.
The final part of the system is a small .NET application that was designed to monitor the processed video files and play them back continuously. This is convinient when you are practicing and want some feedback on your latest moves.
2010 update: I managed to reverse engineer the basics of the Casio EX-F1 USB protocol and have successfully implemented a small command line utility based on libusb win32. This means that the C code should be portable to other operating systems. My personal ambition is to run some advanced video tracking on a Beagleboard, but I am making the source code available to anyone who wants remote USB triggering of the EX-F1.
Jens Skovgaard Olsen, September 2010