Here’s a demo. I move the key frame first with Alt. Look up where it says “Speed” that is above “Direction”. The speed numbers don’t update as I use Alt. Then I move the keyframe with Ctrl and you’ll see that this time it does update. Then I move with with Alt one more time and like before it does not update as the keyframe is being moved around.
What would take longer to do? Sort out the B frame limitation or write a Speed Ramp filter (i.e. it only affects speed going forward)?
I ask this because even though you point out that Time Remap is not meant for speed ramping that is what most people will take it as and try to use it for. Speed ramp has been such a high demand that people will see “Time Remap” as Shotcut’s name for speed ramping. And that’s where the limitation of the B frame issue will rear its ugly head. I can see people being frustrated that they want to do speed ramping but they have go through the hoops of having to convert their file whereas with proprietary software they don’t.
Time Remap is a very interesting feature and I am more than happy to continue testing it so it can grow more and more. But I think the technology you developed here would be best shown off first with a filter that works just as instant as all the other filters currently in Shotcut. If the shorter path to that would be to make a Speed Ramp filter then I think it’s really worth considering.