it should be simple but my brain is refusing to see the way…
how do you speed up a clip so that the start and end frames remain the correct frames, but the overall Timewarp happens over a much quicker time, and with speedramps rather than a linear speed change (which i can do easily)
I don’t know if this is what you’re looking for but, I usually chenge the mode from speed to timing and adjust manually with curves and exact frame placements.
It’s really hard to do using speed. You need to set a keyframe in the middle and adjust it in the animations curves while parked on the end frame and watching the timecode change. I hardly ever use speed for anything anymore.
I find it very difficult to use Timewarp for anything. I’m sure i used to do this all the time (excuse the pun!) in After Effects, and I haven’t used that in almost a decade. Crazy!
You can change the speed of a clip and lock in both the start and end frame.
To change the speed gesturally using trimming, you need to change the “keyframe move mode” from SHIFT to REPOSITION PROPORTIONALLY. This pull down menu is next to the editorial controls to the right of the screen. Apply your Time-warp Timeline FX to the segment and switch to the TRIM mode. When you trim your clip, the speed to the clip will automatically change and keep the start and end from of the segment.
If you also want to manually set a speed in the slider, you need to switch to the RENDERING menu in the Timeline FX mini-tool bar. It may be INTERPOLATION but you can switch that. In the RENDERING menu, you will see an ANCHOR option. Change that to START/END. When you change the speed value in the slider, it will adjust the segment to match and lock the start and end frame.
I’m aware of those techniques (i watched your very helpful videos before posting the question!)…what i am looking for is a way to use the proportional method, but to include an acceleration curve at both ends. Thus creating a smooth speeding up and slowing down of the clip whilst retaining the in/out frames at their correct running speed…if that makes any sense!
All the methods i tried put a constant speed on the clip. When manually adding a curve it screwed up the in/out points or changed the clip length to something that didn’t fit anymore.
Take your segment with its original duration and apply a Time Warp Timeline FX. By default, only one keyframe is placed on the first frame of the segment.
Switch to the Timing menu which shows the exact frame of the source and you’ll see a keyframe at the beginning of the segment. Go to the last frame of the segment and keyframe the timing channel again. This last frame will be the one you want to lock to.
Next go into the editor and switch to the Animation Editor. Select the Timing channel and frame it. You will see a linear curve with a keyframe and the beginning and end. You can now adjust the tangents for each keyframe to create a smooth S curve. Top Tip… ALT+CLICKING on a tangent smooths it out horizontally. So you should now have the timing curve you want and the timing should still be the same as before.
Now go back out to the sequence and using reposition proportionally, trim the segment to change the speed. The timing/speed will change but the curve inside the timing channel will remain smooth which gives you what you are after.
Looking at the General Preferences under animation, the interpolation is set to Bezier but its possible that the Timewarp Timeline FX might be the exception.