Basic instructions for digital video motion analysis in the AP Physics Course

The big picture:

You may also want to look at some background material.

• Digitize the video of an experiment (uses the "iMovie" program on the "G4" computer) and the video codec digitizer comes from Sony . Using them avoids most of the pitfalls associated with digitizing video, which is a particularly demanding application for most computers.
• Edit your digitized video shots into short segments containing only the motion you want to analyze (using MoviePlayer extended by the QuickTime Pro software).
• Analyze the edited shots(using VideoPoint); VideoPoint runs on MacOS or Windows and analyzes digitized video in QuickTime format; it is currently available on the Mac as well as the PC platform.

Needed materials:

• PowerMac G3 or G4 "All-in-one" computer
• video camera or VCR and tape
• video cable
• AC adaptor (if using camera)
• tripod (if using camera)
• audio cable (optional but useful for annotating your shots as you take them)
• meter stick for scaling (position it in the plane of the motion you want to analyze in a place where it is visible in the camera)

Note one other source on material (or, why you should do it yourself): non-Quicktime video from the web, which usually has low picture quality to begin with, can have flaws fatal for motion analysis: unreliable or unknown time-bases or filled with intermittent "missing frames". Video (29.97 frames per second) that has been converted from a film source (which is almost always shot at 24 frames per second at normal speed) contains regularly-spaced duplicate frames, which must be edited out one-by-one before analysis.

Note on other video equipment: unless you have tested a particular computer/digitizer/software combination's suitability for your particular needs, don't buy anything. If you are tempted by the new Macs with built-in IEEE1394 and a DV camcorder, consider the fact that with a video data rate only 10% as great I had no trouble filling a 4 GB disk many times over in less than a year.