Interpolation and envelopes

Paul Fierlinger wrote on 2/28/2007, 1:18 PM
In Preferences/Editing/Interpolation and envelopes/ there is a list of several options for Audio and Video default types:

1. I am working with 720p/24 fps, 2D flat animation. Which of the listed settings should work best for me?

2. I have a vague idea what these do and have experimented with each setting but am still confused as to what I should expect. Can someone either explain the individual settings to me, or point me to the place where I can read up on it. I have checked the manual (book) and made a search under Help and have found nothing.

3. I would also like to find out what what the Motion smoothness and Pan/Crop smoothness numeric settings do and what to expect from these.



Paul Fierlinger wrote on 3/1/2007, 3:24 AM
Interesting.... I'll try that too. Thanks.
Tattoo wrote on 3/1/2007, 6:36 AM
Paul (TIA?)-

- Interpolation: I think people use "Smooth" the vast majority of the time. This means for audio/video crossfades & such each event will fade slowly at first (first 10-15% of the transition), then ramp to a rapid fade (middle 75% or so), and then back to a slow fade for the last bit (last 10-15%). You can see this by the shape of the transition curve (blue line). There may be moments when you want a slightly different look to your transition, but I'd personally leave the default at Smooth.

- Motion/Pan smoothness: I would absolutely recommend setting the default for these to "0" or you'll have some unexpected results. If you are using Track Motion or event Panning to move video around on the screen (like panning across a still picture (Ken Burns effect), a smoothness value of 0 will make your point-to-point movements exactly as you command. As you increase the value towards 1, however, Vegas will smooth or round out the motion.

-- For an example of this, put a still image on the timeline and use either Track Motion or event Panning to move it around in a square path. Set the Smoothness to 0 and watch the result - it will track with abrupt corners like you'd expect. Set the Smoothness to 1, however, and watch the weirdness. Say that your starting point of the square was the upper left, then to the right, then down, left, and back up to the starting point. As Vegas pans right, it will actually pan *up* too, in anticipation of making a nice smooth, rounded turn down. The closer to 1 you set the Smoothness the more your square movement will resemble a circle. There are times when this kind of smooth, rounded approach is useful, but most of the time you don't want Vegas doing stuff you didn't ask it to.

-- I'm not sure if the Pan/Crop Smoothness effects how cropping is handled. I've never dynamically cropped an image/event (started with one size and ended with a different size), so I've never seen this in action. Not sure how a 0 or 1 setting would effect this, but you can always experiment!

-- When experimenting with these settings, I recommend rendering the section in question to see precisely what the effect is. Without rendering, your preview may be slightly jerky and mask the effect. Render to RAM will work fine if your clip/section isn't too long.

Realize that this forum tends to slow down a bit during the week and you may not get the answer you're looking for right away. The "Search" function is extremely useful, too, if you can think of the right words to search by. Best place to start is the thousands of useful posts that already exist on this forum.

Paul Fierlinger wrote on 3/1/2007, 8:25 AM
Brian, thanks for the time you took with your explanation. I think that these settings might also pertain to the interpolations between individual frames when previewing in real time. This is especially noticeable in 2D animation, which is an issue I have to constantly deal with. These one frame dissolves can get annoying, but when not overdone, they are useful. When the interpolation is Smooth, the imagery appears as if it were swimming behind thick glass.

I've been fooling around with these settings so much that I have lost objectivity. I "think" my preferred setting at the moment is Fast with motion smoothness set to 100.0. But then I go to another part of my film and I don't like it -- it's driving me mad; therefore this thread. Does any of what I described make sense or am I being delusional?

I know about the clip resample switches, but the preferences editing interpolation settings seem to have some influence on the playback appearance between each frame as well.

Incidentally, I use a 21" plasma wide screen for my secondary preview device and during these preview experiments I discovered when I uncheck having both previews play at the same time, I get much closer to my 24 fps playback . When I use only the timeline's preview display the speed rate is accurate all the time. With both it hovers around 19 fps.

I understand the need to have patience when waiting for someone to help me out but I have to start talking to myself if I don't want my question to slip out of view.
Tattoo wrote on 3/2/2007, 12:50 PM
Well, I see my previous post isn't quite correct on the interpolation part. The interpolation setting obviously doesn't show a "curve" anywwhere (like the crossfade/transitions I mentioned) - it just effects the interpolation/transition between keyframes (not events like I was sidetracked on). I stand by my Smoothness explanation, though.

I'm sure you've already read this, but from p.252 of the Vegas 7 manual:
-Temporal interpolation (how the pan occurs over time) is controlled by the keyframe interpolation curve type ....
-Spatial interpolation (how the pan occurs within the video image) is controlled by the Smoothness setting of each keyframe. A smoothness value of 0 makes the movement linear from one keyframe to the next. A higher smoothness value makes the path of the pan more curved.

The Smoothness shouldn't have any effect on interpolations between frames, only how "smooth" the PATH your object tracks across the screen *IF* you have keyframed motion via Track Motion or Pan/Crop.

I haven't done animation, so I'm not sure exactly what you're doing, but it sounds like you are trying to use Vegas to "generate" animation. I don't think that Vegas is your best software to accomplish that in - I don't think it's a strength of the program. Have you tried making the animation in an animation program and then importing it into Vegas to do further editing work with?

You're well beyond my knowledge level, so I don't have any other ideas. Someone else probably will, but you'll have to get their attention. I recommend retitling this post to something more appropriate for your needs like "Need keyframe help for animations!" That might bring in a fellow animator like yourself that has extensive expertise. Their may be other settings that you're not aware of that are contributing to your problem.

Paul Fierlinger wrote on 3/2/2007, 1:49 PM
Thanks again Brian. I will do anything in animation but let a machine animate for me; I am a militant manual drawing person and I draw everything paperlessly in Mirage via the Wacom pen and tablet.

I think I found a simple solution to my problem though, which is to fall back to the Default All settings in the Editing Preferences and simply disable resampling in the clip Properties. Now I see no interpolations between individual frames, but I swear that switching between Smooth and Linear or Fast did indeed make discernible differences in the way resampling handled interpolations.

Vegas is a joy to work with and I keep discovering new things to work with which I never thought I needed before.