Well, we’re having some great discussion over at the Time Based Animation thread (http://blenderartists.org/forum/showthread.php?t=87036), and in the meantime I thought I’d run by another proposal by this group.
This is posted on the wiki here: http://mediawiki.blender.org/index.php/Requests/AnimationFeatures#Multiple_Timeline_System
This is sort of a “part 2” to my previous proposal. This would be difficult and fairly pointless to implement without Time Based Animation, so I don’t expect this anytime soon. I would like people to start thinking about this, however.
With time based animation, we would have a whole slew of time dilation effects open to us. But, there will still be limitations (imagine that). Those in the USA have probably seen this advertisement http://www.allstate.com/media/images/Multi_taskers.mpg
This is what the inspiration was for the Multiple Timeline System.
With the “apparent time” and “proper time”/“real time” concepts introduced in Time Based Animation (note: I introduced these through an update a few days after I first posted it to the wiki), it would be fairly simple to simulate the slow motion effects in the commercial through an inverse quadratic curve. Now, we run into a problem: how to easily animate the main actor (Dennis Haysbert)? Until this is implemented, we would have to use the crutch of stretching IPOs, but there is a better way!
First, we would have to define the camera speedup through a time ratio. You could do this manually or use the method described in Time Based Animation and let Blender calculate it for you (ideally, the two should just be interlinked–like the color picker and the RGB sliders). Then you’d create a second timeline and move everything that you want to work on the second time. Then, you’d use what I call “time parenting.” If you parent the timeline to a camera, what blender would do is stretch and squish the timeline dynamically to maintain a constant apparent speed with respect to that camera. In the timeline window, the green line would advance across the two timelines, and slow down and speed up to indicate the apparent speed of the animation, while the first timeline would always maintain natural time. Of course, you could do this backwards as well. You put the main actor (Dennis Haysbert) into the first timeline, and everything else onto the second timeline. This time, you DON’T time parent, but you stretch and squish the second timeline by hand to your heart’s content.
I realize that this would take A LOT of coding, so I’m not demanding anything except consideration. Think of all those music videos where the band is playing in an intersection and the crowd and cars are flying past them in a blur. Ideally, you should be able to manipulate output based on which timeline it is associated with in the composite node system. There would be no more need to rack your brains to work with time effects!