Unless I've missed something (occasional user of FCP) FCP doesn't seem to give you the ability to gradually speed up / slow down video over time correct? That is you can jump between one speed to another. Assuming this is correct then...

What's the best approach for an FCP user to be able to create/incorporate clips that have linear/graduated changes in video speed over time? Which tools/plugins?

Hi Mixed-up
Think you are a little mixed up FCPX has some great built in abilities for speed changes and allowing you to change the "ramping". You can apply this to clips, ranges within clips or transitions.

See this video by Ben Halsall for some of these…

See also this by Apple… support.apple.com/kb/PH15834?locale=en_US&viewlocale=en_US

If you do a search for "speed changes in fcpx or ramping" you will find lots of info.
Hope this Helps, Greg

thanks - yes I've tried the "step change" change in speed possibilities in FCP in the past but interested in linear change in speed. But I see there's some transition options there for smoothing I had not seen before so I'll try these out (thanks)...

It seems Twixtor is one of the well know plugins for remapping so I'll have a look at this. Not sure if it will allow linear change in speed, e.g. say over a 5 second period linearly ramp up from 100% to 600% speed for example.... interpolating/frames etc

Some softwares have the graphic represantation of a bent keyframe path that suggests a proportional increase/decrease of playback speed. I wrote „suggest“ because, if you try and do the maths yourself, you will see that this is not possible with whole, „integer“ frames as the timebase. It appears that frame interpolation will allow it, but it doesn‘t. Because while it IS possible to generate a „stepless“, smooth pixel motion or optical flow, the phases have to be remapped to whole frames again, and there is no „floating point“ playback speed. The ramp with the sections of calculated slow down and speed up are actually as good as it gets. Wouldn‘t this be more accurate with more time blades? Only in theory and in the imagination. You can calculate the position a single pixel probably had in frame x, given that just this frame had had a shooting rate of 43,578 fps. What you really get then is a slightly different amount of motion blur - that‘s what optical flow does.

Finally: what would such a linear speed progression be good for in terms of perceived flow of time? We are not trained to see and judge anything else but realtime. We take an FCPX speed ramp with speed transitions and optical flow already for „linear“.

Make ONE Speed Blade cut in the middle of the clip. One side is 100%, the other side is whatever you want it to speed up to or slow down from or whatever. Then pull the Speed Transition range to show were the speed change starts and stops on each side. Done.

I do this weekly for a couple of TV shows, very fast, very easy.

interesting and thanks for the response Axel...also wondering now if the video I've seen in the past I thought they were ramping down "linearly" whether they actually were or not...

thanks FCPX.guru - got to get back to it and try this out...