Which FX is that? Which parameter has the problem? Which version and build of Vegas Pro?

WIN10 1709 ,VEGAS 15 build321, Piccture in Picture ' parameter——position,

Actually all vegas and all OFX has the problem, I think it's a Design flaw. The OFX's Keyframe curve can't accurately control parameter.

I just want adjust parameter by  Keyframe curve to get the very smooth motion effects.

just like what after effects 's keyframe curve can do.

Did you try adjusting the curves on the nodes? (the link shows one active, but not the other)

Did you try adjusting the curves on the nodes? (the link shows one active, but not the other)

Two pictures are the same. Node is normal, I want to use curve to control smoothly, but it seems vegas' this function is defective. I can't get a more fast effect than the preset "fast fade".

Your first image link is broken for me. Please post images directly to this forum using this icon:

I can confirm this problem. When switching from lanes to curves, manual control is possible. This hand-drawn curve will only be applied correctly if there is no direction reversal. Overshoots are not interpreted correctly.

Just checked for VP15, VM14 and SMS12.

Edit: It seems that the values from the drawn curve are always ignored. The ProType Titler shows how it should work.

Anyone care to post a simple step-by-step walkthrough or a project using generated media to illustrate the problem?

It's more serious for me. Manual curve animation just doesn't work at all. Whatever shape the curve is, the result is just the same as a "Smooth Fade".

I tested by eyeballing it in the Gaussian Blur FX. Then I tried it with the Pixelate FX, a) because it's the one that's shown in the VEGAS Help (so it should work), and b) because it's quantifiable, by counting the number of pixels. However it is a bit tricky to test because you don't really get any countable pixels until value 0.9.

This happens for me in VP12 as well as VP15, so it's a bug that appears to go back a long time.

Can anyone show that the outcome of any manual curve animation is any different from a "Smooth Fade" in any FX in any Vegas version?

I think that is the same with all FX. I have not yet seen where it works. In ProType Titler it works correctly, but there it is part of the generated media, not an FX.

If you set a new keyframe on the curve, the current numeric value is taken over and you can see the deviation.

What seems to happen to me is that the spline curves are adjusted in a way where you end up with overswinging.

If you enable the curve mode and then the "manual split" mode for a keyframe, and move the endpoints up a lot, then you will end higher then the next keyframe. It is up to the user to adjust in the Manual split the spline function in a way how it makes sense to him.

See for example this Picture, where such a function is used in a drawing to some extrem extrend.

http://www.corel.com/img/content/products/cdgsx5/tutorials/curve_tools/CDGSX5_Tut07_Drawing_lines3.jpg

But that is what this function is for!

So I think there is nothing wrong here. But one has to adjust that with care.

The problem is that the numeric value does not correspond to the curve. This is clearly visible when overshooting. You can also see it when a new keyframe is added to a drawn graph. Then the point jumps to the right place.

Demonstrating the issue with Brightness and Contrast:

Link to demo project

I think the misunderstanding is that the curve itself would represent virtual keyframe positions (and so parameter values), but the curve only visualize the speed of change between the given keyframes, it's not the visualization of the parameter values. It's temporal interpolation and the curve only shows how fast or slow parameter change between the keyframes.

I think the misunderstanding is that the curve itself would represent virtual keyframe positions (and so parameter values), but the curve only visualize the speed of change between the given keyframes, it's not the visualization of the parameter values.

But wouldn't the net result of that be that the curve would approximate a series of virtual keyframes anyway? To my mind they're much the same thing.

Unless I've completely missed the point, there is no way that the brightness at 3.5 secs in my demo above should be equal for each track, or that moving the curve's tangency handles around should not significantly adjust the brightness.

Nick, you are right in that is how it should work. But it appears that it doesn't.

Quite surprising that this bug doesn't seem to have been mentioned before. I guess most users are happy with the standard curve shapes. I've never used a manual curve.

I just want adjust parameter by  Keyframe curve to get the very smooth motion effects.

just like what after effects 's keyframe curve can do.

@lan-mLMC If it worked correctly, the curve shape in your 2nd picture link would give an "overshoot" in motion and the picture-in-picture would "bounce back" to the final position at the end of the animation. Is that really what you want?

"But wouldn't the net result of that be that the curve would approximate a series of virtual keyframes anyway?"

Virtual keyframes would almost always be there when animating FX parameters. Changing the interpolation curve now would only change the distance of those virtual keyframes.

Here is another screenshot to demo:

There are three keyframes which represent same luma value of the HSL FX. Now you may think the highest and the lowest peaks of the curve would represent different luma values, the lowest to represent lower luma values and the highest to represent higher luma values.
But because the three keyframes represent same luma values and curve just represent the speed of animation between (same values), there will be no change at all along that whole curve.
Expected behaviour.

"But wouldn't the net result of that be that the curve would approximate a series of virtual keyframes anyway?"

Virtual keyframes would almost always be there when animating FX parameters. Changing the interpolation curve now would only change the distance of those virtual keyframes.

Here is another screenshot to demo:

There are three keyframes which represent same luma value of the HSL FX. Now you may think the highest and the lowest peaks of the curve would represent different luma values, the lowest to represent lower luma values and the highest to represent higher luma values.
But because the three keyframes represent same luma values and curve just represent the speed of animation between (same values), there will be no change at all along that whole curve.
Expected behaviour.

I agree with all of that.

But when the 3 keyframes represent different luma values, the behaviour of the manual curves is totally bugged.

Could you share a sample project?

The only buggy result (in a user sense) I could repro was when pushing the curve interpolation that hard it peaks go to infinite. That would kind of reset the parameter to one of its scale end.

Another thing one should take care of when using Pan/Crop or Track Animation, there are two different types of interpolations. The temporal interpolation which is available via the keyframes' context options, and the spatial interpolation which is available via the smoothness slider of the editing area only. There is no such a thing like spatial interpolation for the OFX and no kind of interpolation which would cause parameter swings exceeding a keyframe defintion of OFX.

So dependend on which interplation type is modified, it is hard or even impossible to compare Track Animation or Pan/Crop animations with any of the OFX animations.

In ProType Titler we can see how it should work, I think.

Quite surprising that this bug doesn't seem to have been mentioned before. I guess most users are happy with the standard curve shapes. I've never used a manual curve.

The faulty behavior was the reason why I did not take it.