Sorry, yeah, I had a feeling I could have described it better.
At the moment, let's say I have ten frames zooming into a Mandelbox, but as well as a zoom, I want the camera to turn between frames 4 and 5.
Right now, the only way I can check that the spline created by the control points at the keyframes follows a nice smooth path between frames 4 and 5, and doesn't skew wildly (through walls and such) is to render out a load of preview frames (say 160x120) and preview the whole thing in Vdub.
This is entirely doable, but it seems a little long-winded when all I want to do it to check if a set of keyframes make a nice smooth flightpath, or (because I've placed a bad keyframe) the Catmull-Rom Spline bends in an unexpected way and the camera goes through a load of walls.
As an analogy, if you think of something like the timeline in say 3DS MAX or Adobe Flash, where you create a keyframe at one point, and then move an object and create a keyframe at another point on the timeline, you can then drag the pointer along the timeline to see how the object will 'tween' between the two keyframes. (I realise the analogy breaks down slightly because keyframes are treated a little differently in those programs).
Maybe something like this (just as a for instance, off the top of my head):
An extra slider control in the Timeline window, which when I have say frame 4 selected, as I move the slider along, interpolates along the Catmull-Rom Spline towards the position in frame 5, so that when it's at 50%, the display window shows where the camera would be when the render process reaches the point halfway between those two frames, at 0% just shows frame 4, and when it's at 100%, it's basically showing frame 5 (more or less), but the point of this being that it follows the same Catmull-Rom Spline that the animation rendering process will use.
Don't worry if it's too difficult to implement. I think I'm getting better at understanding how to avoid the wild spline bends, and like I say, I can render out a load of previews, but I have a feeling that the process would be made a lot quicker if I could just 'scrub along the timeline' like I can in MAX or Flash.
Thanks very much for your consideration though.