"Set Layer Start Time" doubts

[Reindeer]

This is not really a "How Do I...?" but more like a doubt. I'm using ASP for a major project (for big screen projection, so, quite detailed) and I can say It's working well for me. One thing I sort of fight with, though, is how the Set Layer Start Time command works, especially how it impacts editing my material (vectors, bones, etc).
My doubt is: when I set the Layer Start Time, does that change my 'Frame Zero' position?

I'll make an example. Let's say I have an animated asset (say, a bird flying cycle) and I want it to appear on frame 100. What I often do is I create the bird in a separate ASP file and then either import it or copy/paste the layer in my main file. This will automatically paste or import the animation at frame 1. So, then I use the Set Layer Time command and tell it to start on frame 100. So far so good, I see the little green Play symbol move to frame 100. Now here my doubts arise. Is frame 99 my new frame 0? Or maybe are all the frames prior to frame 100 (99, 98, 90, 80, 50 etc) all 'frame zeros'? Is the frame previous to the Start frame always the zero frame?
I am under the impression it is a frame 0, but then sometimes ASP seems to not treat it as such. For example, when I change shapes of vectors on the previous frame to the Start frame or on previous frames, I see it adds keyframes (shape keyframes, color keyframes, etc). Something it would not normally do if I were on the 0 frame because frame 0 is our 'neutral'' editing ground.

So I'm a little uncertain as of what and where I'm supposed to do my editing of bones and vectors in such cases.
I'm sorry for this wordy post, I hope I explained myself well enough...

[synthsin75]

In AS11, frame zero is the setup frame, regardless of where you've moved it in the sequencer (which is what "set start time" does).

[Reindeer]

Right. So if my Layer Time starts, say, at 100, then frames 1 to 99 are considered like any other frame? If zero is editing frame and 100 is Start Time, whatever falls imbetween is a sort of 'limbo'
I don't know why, but this concept tends to elude me quite often. I mean it hasn't yet sunken into my head or become second nature like most other ASP11 features have.

[synthsin75]

Yes, frames 1-99 are like any other frame in AS11. There's no "limbo", it's just an easy way to move the timing of a whole layer (just like dragging the layer in the sequencer). Older versions of AS did have a setup frame that floated with the layer start time, but this was especially confusing.

[Reindeer]

On the other hand, it seems to me as if ASP11 does put an extra keyframe right before the one you choose to be the new starting one. Imagining start at frame 100 again, I see ASP lets me move the position of the character without adding paths (the straight line path which I've come to learn indicates the default position) just like it would do if it were frame 0, but it's actually frame 99. Same said for layer rotation and size, I can change them on the frame before the actual starting frame. As a matter of fact, if I edit the layer's position, rotation or size on frame 0 when the layer has a different starting frame, it will do it by adding keyframes. Which, if I'm not wrong, shouldn't happen on frame 0.
So, unless I'm wrong, it actually does sort of 'advance' frame 0 to the closest new frame to the starting one.
I might be doing something wrong here, I admit do find this a little confusing. Not to the point It's impending my work, just a thing I need to keep an eye out for.

Anyway, aside getting used to a little things like this I am really enjoying this software. What I like about it is that it lets you invent your own solutions. I get loads of mileage out of what seem to be pretty simple building blocks. Although one can do post with Adobe AE, I could see an ASP with a little more power in fx and compositing as quite a killer. Just digressing.... : )

[Greenlaw]

Will you be rendering from 100? If so, it really doesn't matter. What only matters is what's being rendered.

Frame 0 is always the setup frame, so the animation will always attempt to interpolate from the setup pose to wherever your first keyframe beyond 0 is. (Technically, frame 0 is really your first keyframe.)

If you do need to render the hold from 1-99, and you've already posed frame 100, you could freeze the pose at 100 and then copy those keyframes to frame 1 and set the interpolation mode at frame 1 to Step. This will hold the animation until the next keyframe (frame 100.) (Actually, that's a 'backwards' way to work--it's really easier to make your first pose at frame 1, and then go to 100 and just freeze the pose there.)

Personally, if 1 - 99 is a hold, I wouldn't bother with any of the above at all. Just start rendering from frame 100. Then, in your compositing or editorial program, you can just hold the first rendered frame (100) at frame 1 and release it at frame 100 on the timeline--that would be much easier and faster to do with the same result.

[Reindeer]

Actually the whole movie starts at 0, but I have layers that start at other frames. In this particular instance, I have a series of different (and unrelated) animated events which appear in sync to a musical soundtrack.
So I'm preparing them in separate files and then importing them at the desired frame number. Say, I prepare my "bird flight cycle" in a new file, save it and then either import it or copy/paste the layer at the point in the music where I need it.
This always requires a few adjustments, for example if the setup bird character was created in the stage area, I need to move it's setup position out of sight (outside the stage area), otherwise I'll see it overlapping in previous frames. I could, I guess, as an alternative, make the bird invisible up to the Start frame.

On a related note, I see ASP automatically makes new layers who's start time is after frame 0 invisible prior to the start frame. Say, a new vector layer created on frame 100 (provided you have unchecked the "drawing tools only on frame 0" box in prefs) will be automatically invisible on frames 0 - 99. Which seems to me handy. It would be also nice (if it doesn't exist already) to have that automatic invisibility option also when you tell a frame to start on a certain frame. Say, telling a layer to start on frame 100 would make it so that all frames prior to that would be invisible. Does that make sense?

[Greenlaw]

Yes, I believe it's supposed to work that way.

The feature makes sense in theory but more often it's been super annoying. Well, to me anyway, since I don't typically want things to be 'invisible' unless I explicitly keyframe them to be so.

[Reindeer]

Ha, yes I guess one should always be wary about wishing out loud "why not add the option to..." because that's what ends up making software bulky.