I'm making a video and I want to do keyframed speed changes. That is, I want to have a video gradually get faster or slower at different points. I have been a user of kdenlive for awhile but have unfortunately found that is unable to do this. Can any recommend software that can definitely do this?
After a year of searching I've finally come across an answer. For this you'll need Blender. I'm using 2.56 beta.
Open Blender and switch to the Video Editor
Add a video to the editor
To make things easier combine the audio and video clips (make a meta clip)
With the clip selected add a Speed Control effect
In the effect properties on the right-hand side first untick "Stretch to input strip length". Then hover your mouse over Speed Factor and Press "I" on your keyboard. This field will go yellow.
Move to a different point in the movie. Change the value in the Speed Control field and then hover your cursor over the field and press "I" key again. You'll see the graph on the left-hand side change to reflect your actions
Do this a few more times and you've just changed the speed of your movie using keyframes!
There are many bug reports and feature requests in programs for easy keyframe editing of the speed of movies:
VLMC Bug 205
Novacut Bug 680865