Note: These instructions are specific to the Weather in a Tank commercially available rotating table.
Recording the video with a Mac
The video captured by the CCTV camera on the table is of reasonable quality, but the camera outputs the video via a standard video cable.
A standard video cable can be hooked up to an ordinary television, but if you’d like to record on a laptop or project in a classroom in the usual way (through the laptop’s video out), you’ll need an adaptor.
We use the StarTech S-video/composite video to USB adaptor (thanks Pete!), for recording the video from the table-top camera.
Unfortunately, the driver provided with the adaptor is for Windows, and I use a Mac. Using the software VideoGlide, we were finally able to record some footage.
The original movie was 25 minutes long, and 1 GB, which is too big for web! Note: If you’re performing one of the demonstrations that doesn’t have a change in rotation rate and is also slowly evolving, you can record the video in VideoGlide as a time-lapse with a frame every, e.g. 5.9 seconds for a 10 rpm reading on our table. This cuts down on the video size and also reduces some of the problems associated with uneven lighting reflecting off the water surface as the tank spins. While the lighting may still be uneven, if the frame is captured when the tank is in the same position (once per rotation), it reduces the flashing effect.
Cropping the video using a mask
Using QuickTime 7 Pro, I then cropped the video (see How to crop a quicktime movie and trimmed out the spin up at the beginning. The video was then 20 minutes long.
Speeding up the video
Since rotating table videos tend to be more spectacular in fast-forward, I then sped it up (see You gotta speed it up, and finally exported the movie using Quicktime’s
Export>Movie to Quicktime movie with the settings H.264, frame rate current, and fast start. This last step of exporting to Quicktime movie is important if you’d later like to upload to YouTube. If you only save “as self-contained movie”, then some of the settings (playback speed and cropping) may be lost!
Note: The export process takes a long time! I estimate it was about 1 hour for the 20 minute video.
Here is the final video.
If watching it in fast forward makes you dizzy, try the original.