Twixtor slow down to footage and to separate alpha matte how?

[Pierre Jasmin]

The Foreground layers Mattes is an option in Twixtor PRO (it will use it when retiming)
To twixtor a matte by itself you can set the ALT motion source to the live action source assuming they are time-aligned. The ALT source is the one use to perform the tracking then.

You can post the question on our forum here at creative cow.

Pierre
http://www.revisionfx.com

[Barend Onneweer]

I think your problem would be solved by applying the alpha to the clip, then precomposing and then applying Twixtor to the resulting comp.

If I’m understanding you correctly.

Bar3nd.

Forum COWmunity leader for:
ADOBE AFTER EFFECTS
MAGIC BULLET SUITE
INDIE FILM & DOCUMENTARY

[Rafael]

Hi Pierre,
So I followed what you said. I have 3 layers:
Layer 1 is a pre-comp of the footage
Layer 2 is a rotoscoped of the layer 1
Layer 3 is the footage

I applied Twixtor 4.5 to the Layer 2 and 3 and set the ALT motion source to Layer 1.
It works for Layer 2, but Layer 3 show that pinkish-red, nothing. It doesn’t make sense at all to me, if Layer 2 is working why not Laayer 3?
I followed the tutorial, the ‘Alternative Input’ is not documented as well as other sections, no After Effect project. I really don’t get it. ;(

[Pierre Jasmin]

Does your roto has an alpha channel?

If you do the roto in AE, you have to make it in a different comp

Comp1: RotoComp or if it’s footage use Set Channel to put roto matte into alpha
Comp2: RGB source(turn off layer)
RotoComp
Apply Twixtor to RotoComp and set ALT source to RGB source

Pierre
http://www.revisionfx.com

[Rafael]

I don’t understand what you wrote! It’s confusing.
My layers are:
Layer 1: the original footage RGB, layer turned off
Layer 2: filmstrip created in Photoshop, no alpha channel based on the footage
Layer 3: the footage RGB

So I set up the layer 2 & 3 ALT to the Layer 1 on which I want to be based.

I also did a version where I created a pre-comp for each layer, so my layers are long enough for a speed of 50%.

[Pierre Jasmin]

You need to set your composition to be duration of the amount of frames you need. In AE an effect cannot increase the duration of a sequence so you have to pre-comp and set duration appropriately or you can also as per above set the top layer as a solid (make the solid after you changed the comp duration) and apply Twixtor on the solid where color source is layer 2 and ALT source is layer 3.

I am not sure I understand what layer 2 looks like. Is it a black and white image of the matte? The scenario I am describing here is to retime a matte without the RGB. As Barend said maybe what you need is just “set channel” (ae included effect) the roto matte into the alpha of the color source. When you do such thing you need to make that into a separate comp as AE does not honor effects applied to a layer when you ask for frames from a layer (unless it’s subcomped).

Again Twixtor Pro only supports embedded controls for multiple-layers (defined by mattes)

Pierre