About this video...
Performed by Lara St. John, recording courtesy of Magnatune.
This is one video in a series of experiments described here:
http://www.musanim.com/bwv1007m1/
Q: Why is the video so jittery? Can't you do something about that?
A: Yes and no. When videos have fast motion, it looks smoothest if the frame rate of the video matches the frame rate of the playback system. My computer display here at home runs at 60 fps (frames per second), and when I view my videos here at that rate, they're beautifully smooth. But when I upload a 60 fps video to YouTube, they convert it to 30 fps by mixing pairs of frames together, so that each frame becomes a kind of blurry double exposure. Therefore, I make 30 fps versions of the videos for YouTube. If you play a 30 fps video back on a system running at 60 fps, it looks jittery, but at least the individual frames look right. If your internet connection is slow, YouTube (or your browser software and/or Flash player) may reduce the frame rate even further. The effect becomes more noticeable as the scrolling speed of my videos increases, so I tend to use slower scrolling speeds than I would otherwise (as a compromise), but in this one, other aspects of the animation (the big patches of color and the irregular outlines when the melodic path changes direction) were less visible when I squished the horizontal scale, so I pushed it further in the fast and jittery direction than I would have otherwise.
Q: What do the colors mean?
A: The colors indicate "pitch class" (that is, note name, C, C-sharp, D, D-sharp, etc.). You can read more here about the system I use:
http://www.musanim.com/mam/pfifth.htm