Hi..
In Combustion, you can change the speed of a clip, but it is ALWAYS at a FIXED speed rate ( NO dynamic ramping - or changing speeds.)
Here's how to do it:
Start with the Time Stretch options to stretch or compress the duration of your footage. The duration of the clip is updated according to the changes you make to this option. For example, if you reduce the speed of a 15-frame sequence set at 30 fps to 50%, the duration of the clip becomes 1 minute. The frame rate of the clip is not affected.
Next, make sure you use "Frame Blending" (in conjunction with the above option) to create a smoother transitions between frames when you extend the duration of your clip. If you extend the duration of your clip with Frame Blending disabled, the new frames added are duplicates of existing frames. If you enable Frame Blending, new frames are created by blending adjacent frames together.
As an effect, you can also specify a "hold duration" for each frame. For instance, if you set the Hold Frame Duration to 2, the footage moves ahead one frame as the composite moves ahead by two. This is the same as setting the frame rate to 15 fps.
If you change the frame hold duration, the clip duration also changes. By setting the hold duration to two, you are doubling the length of the clip. Set the frame hold duration to three to triple the length of the clip, and so on.
This is a particularly useful setting for cartoon animators. For instance, if you import an image sequence for which each frame has to repeat four times before advancing, the associated frame rate would have to be 7.4925 fps. It is much easier to set this using the Hold Frame Duration option than by trying to calculate this value in frames per second.
FYI: This stuff is all from the on-line help ... Just Hit "F1"
Again, the speed changes in Combustion are all at a fixed rate... Combustion does not have "speed ramping" (variable speed) ...
However, you can get a PLUG-IN to do SPEED RAMPING. The below plug-ins allow for curve-based speed changes, with frame interpolation and blending..
1) Twixtor by RE:Vision Effects -
link: Http://www.revisionfx.com/rstwixtor.htm
2) Retimer by Reavliz.
link: http://www.realviz.com/products/rtpro/index.php
bye,
jack