Working with BVH and speed

[Tommy Rampal]

So there's been a few animations I've made where I've found that they are too slow or too fast, and have tried to come up with an easy way to optimize their speed.

The quickest method I've found is to tweak the frame rate to odd numbers (e.g. 30 into 37FPS), to fine tweak the speed.

Though most of my animations are around 1-2 seconds at a time; is this a good idea, and are there better alternatives out there? (e.g. adjusting the speed without changing the frame rate) I'm unsure how Secondlife treats my animations on upload with odd framerates, though, they look ok.

[Medhue Simoni]

I could be wrong here, but I'm pretty sure 30 FPS is as fast as animation can play in SL. So anything over that is probably not going to show up as faster.

There are very few animations that need to be 30 fps. The movement would need to be really fast, like that of a laughing animations that requires the avatar to jerk back and forth extremely quickly. If the animation does not require 30 fps, then you are just adding more data to the whole system with very little benefit.

Most of my animations play at a rate around 10 fps. My motion capture are usually around 15 fps, with some dances and others crawling into the mid 20s fps. Even some motion capture strikes that I have are only as high as 25 fps. Now, you might ask why. It is simple, I just don't need them to be that fast, and I want the animations to load quickly for the user. Plus, yeah, you can adjust the speed later if it is too slow.

How do I fix speed? Ok, again, you can just up the fps of the animation. Or, what I would do most of the time is eliminate, or take away frames that are unneeded. In Slat, the program that I use, I just have to select a range of frames, then click the frames tab and slowdown, or speed up the selected range. The program will either take away frames, or add them, while blending all the rest of the frames to make up for the differences.

[Tommy Rampal]

So uploading my speed adjusted animations means secondlife will clamp them at 30? I think i read on the wiki that it can be 45? I mocap combat animations at 1-2 seconds at a time, so this would still benefit from the 30fps with minimal loading time right? Regarding loading time, isn't it literally text data being downloaded?

[Medhue Simoni]

a 1 or 2 second strike animation is not going to be very large, so that is fine. Yes, it is text based, and a simply 2 frame animation is super small, but when you are talking animations at 30 fps, then you are talking alot bigger files. Consider that, if your strike is 30 fps, and is 60 frames, that is going to take longer to load than a strike that is only 20 frames.

[Tommy Rampal]

I discovered bvhacker has a pretty useful tool when trying to compress animation size. Resample to 1/2 frames literally cuts the frames and framerate by half, which in most cases work great.

[Medhue Simoni]

Oh, and just to put this in context. Yes, animation is just basically a text notepad type of document, but to put this in terms 1 can relate to, imagine an image file. An animation that is 30 fps and 30 seconds long, equals out to 900 frames. In kilobytes, that would be around 425 kbs, which would equal something similar to 1 1024X1024 texture. In animation terms, that is fricken huge, and unless it is a fast moving dance, that is a bit much to expect that animation to load quickly. Imagine being in a room full of avatars with every single avatar using 30 second 30 fps animations, and your pc having to upload all of them to see every1 move. This is why, even with motion capture stand animations, if they don't need 30fps, and you can have something that looks really smooth with 15 fps, it is best to stick to the 15 fps, and cut your data in half.

[AprilMae Devin]

I love bvhacker! Its a very helpful little tool! And i use the 1/2 sample frequently but dont forget to "knit" once you 1/2 frame or you'll get a little jerk from last and first frame.