Few question regarding velocity envelope

S

sammysammy

Well-known member
first let me say ill be working with 60p footage (gh1) , my final output would be 24p, here a few question, if you guys dont mind guide me with them

1)can we achieve similar results using velocity envelopes as does optical flow in apple motion? (kind of faking 60p to look 120p)
2)would shooting higher ss than 1/120th help with that process. something like 1/200? or more?
3) how can i manually set the velocity envelope value(exact % value) rather than using the mouse to get a value (using the mouse i have hard time getting the right % it skips,for example going up or down with the mouse i may go up or down by 15% in value)
4)any additional things or steps i need to do inside vegas to make this work better?
thanks for taking the time..
 
1) Unfortunately not. Vegas only allows you to blend frames rather than interpolate them to get the inbetween frames.
2) Not really. Because you're still going to end up with every 2nd frame being a combination of the frames before and after it. However if you're shooting fast-action, you may still want to use a higher shutterspeed anyway.
3) Right-click on your points (the keyframes on the envelope - there is one at the start of the clip by default) then select 'set to' and enter the value as a percentage.
4) If you go into the clip properties you can either force or disable resample. Forcing resampling with get slow motion be creating in between frames which are a blend on the frames before and after it. Disabling resampling will get slow motion by repeating frames. So if you slow down to 50% each frame will be displayed twice. Unfortunately what's missing here is an 'interpretation' method, similar to Apple Motion, After Effects or Twixtor, where adjacent frames are analysed, and an 'estimated' frame is created in between.
 
You can interpolate fields when de-interlacing footage but you cannot interpolate new frames. You cannot analyse two adjacent frames and have the software create a new 'estimated' frame in between. It can only blend existing frames which usually results in ghosting.
 
But that's what it does when it resamples the footage -- it interpolates the frames. It may not always do a bang-up job with it, and other software may do it better, but to say that Vegas can only blend frames isn't quite right.
 
I am under the impression that 'interpolate fields' is used when deinterlacing. So if I set my project properties to 25p, import a 50i file and set my field order to 'none - progressive' and deinterlace method to 'interpolate fields' then what it is essentially doing is throwing away every second field. Then I have a problem that every second line of my progessive image is blank because I've thrown that data away - so the interpolation guestimates what data should go in those gaps to create a full progressive frame.

I suppose whether or not Vegas' slow motion uses interpolation comes down to how you want to define 'interpolate' and whether or not frame blending can be considered to be interpolation - but in any case setting the deinterlace method to interpolate as you suggested should have no bearing on how the slow motion frames are created (but it will have an affect on what data is available to be resampled and how the new frames are displayed).
 
You're correct about the deinterlace method; I had a brief mental hiccup when I was thinking about resampling. (Mea culpa.)

However, according to all the documentation in Vegas (and generally what resampling does), when Vegas resamples, it interpolates frames, and it's not a simple frame blend.
 
I tried this the other day while looking for a Vegas compatible way to do something like Twixtor. It's definitely blending frames.

Still looking for something that can interpolate frames or otherwise produce a smooth(er) looking timing remap.
 
Well, of course it blends some frames; that factors into interpolation. The data has to come from somewhere, and unless you happen to be hitting on a mathematically-even distribution of frames, it can't just fill in frames. The necessary time samples wouldn't be there.

But as I said, sure, there's other software which does it better.
 
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