The first derivative of the playback head vs. time graph, i.e. the local slope, gives the current playback speed. The second derivative, i.e. the curvature, shows whether we are accelerating or decelerating playback. Once you draw some spline lines, it is really hard to tell where you are accelerating or decelerating playback, or whether playback is slower or faster than normal at some point.
For me it would be important to be able to read the local angle of the line, and also the curvature. Maybe this information could be displayed by the coloring of the line. Since you can only display one color, you would have to make a switch for displaying local slope or local curvature.
Vojtech, do you think this is realistic? Of course I am just hypothesizing here, so I cannot know if that would really be a big benefit for desinging new curves more intuitively. But I guess so. As it is now, it is really difficult to come up with new curves, I feel like being in the dark a bit.
Maybe I am lucky and it is quickly realized because you already have everything you need in place.
