Recording a movie with an alpha channel

[Florence Artur]

... doesn't seem to work the way I'm used to. I want to record a movie that I will superimpose on top of another one. I tried the same thing I did with SA 3 and it doesn't seem to work: In preferences, I set "Movie > Embedded Alpha" to "Layer Alpha". I created a new layer, set its alpha to Full off, enabled Paint Synth Alpha, and started recording my movie (using New movie stream and Autowrite). Then I painted on my new layer. I expected the movie's alpha channel to be the active layer's alpha channel, but that didn't work. The movie doesn't have an alpha channel, or its alpha channel is all white. I thought I'd try working on a single layer to avoid confusing SA, but if I set the alpha of that layer to full off, then I can't see a thing, everything goes black. In SA3 there was an option to view without the alpha channel but I can't find it in SA4. What should I do? I hope I made myself clear :-/ By the way, I also noticed that my layer alpha is lost when I save the canvas to tiff format. It's there when I save in Photoshop format. Thanks Florence

[Synthetik]

Ok, i just ran a few tests, and generating movie streams or action processing movies to generate movies with an embedded alpha channel works fine in version 4.

Things to keep in mind.
1. In the movie preference tab you need to set the Embedded Alpha preference to the appropriate setting. So your the case you are interested in you want it set to layer alpha. Note that this one preference setting replaces the 2 separate settings options in v3.5, since in the older versions there were separate settings dialogs for movie streams and for action processing and all movie output is now controlled by a single set of movie preferences in v4.

2. You do want to enable alpha for view (canvas : alpha menu flag) and you want to make sure the paint synth alpha enable flag is also turned on.

3. Setup the PASe appropriately. I used a really simple paseq that set the canvas to black and then set the alpha channel to 0% and then auto painted a few paint strokes. i needed to set the alpha channel to 0% since the first step sets it to full on when the canvas is set to black.

4. Make sure the compression codec you choose actually supports embedded alpha. not all do. animation codec with millions + does, so that's a good test if you seem to be having problems.

...............
In v4, the 'canvas : alpha : enable for view' menu flag turns on alpha compositing when the menu flag is checked. So it's like the old alpha popup in the old layer palette. So to view with out the alpha compositing you would just turn this menu flag off.

If alpha is enabled for view and you set a layer's alpha channel to full of, you would expect that what you would see is whatever you have specified as your alpha background (canvas : alpha : background menu options).

[Florence Artur]

Well, I suppose you can say it works fine, but I liked the way it worked before :-)

In SA3, the option "layer alpha" meant the alpha channel of the active layer. In SA 4 this doesn't seem to be the case, I suppose it must be an addition of all the layers alpha. I'm sure it has its uses, though right now it's a bit frustrating for me.

I guess I'll have to go back to using paseqs in this case then. Thanks for the help!

Florence

[Synthetik]

Are you referring to the old Layer View option for 'Current Layer Alpha Only'?

So yes, that old alpha only view option feature is not currently available in v4. You just have 'view current' and 'view all' right now. I agree it can be extremely useful so i'll look into what it would take to get that going in v4.

Right now you'd have to use the 'canvas : default color : layer alpha' menu option if you wanted to try and look at just the alpha channel. And then undo when you were finished looking to get back to your original canvas layer.

[Florence Artur]

No, I am talking about the option in movie preferences. In version 4 it's called Embedded Alpha, in 3.5 it was Out Alpha, but I expected to work the same and they don't, as far as I understand.

What I used to do was use put image from my movie on a background layer, then paint on another layer and then only use this layer's alpha for the movie.

Apparently in SA4 I can't do this any more, I have to work on a single layer. I guess it's not as big a problem as I thought, I just need to get used to it :-)

[Synthetik]

You should be able to do the same stuff you did before in v4. That feature hasn't really changed, there's just one preference option now for embedded alpha that covers both movie streams and processed movies in stead of separate settings options for both.

[Florence Artur]

But have you tried it with TWO layers? It works fine for me with only one layer, but if I create two layers and want only the active one to be transferred to the alpha channel, it doesn't work that way.

There were separate options for movie streams and processed movies? Oops, I never noticed. But I did notice that the preferences are much easier to find in v4 :-D

[Synthetik]

You don't have to use a PASeq if you don't want to. I just used that for my quick test. You could hand draw and output via a movie stream if that's the output style you want.

[Florence Artur]

Ah yes, you're right, if I disable alpha for view then I can do what I want I think. I didn't know how to do that before, and since I couldn't work on top of a background visible layer as I did before, I couldn't see a thing when I set the alpha to full off.

I think I have it now, thanks :-D

[Synthetik]

Ok, i reworked the version 4 code to support the old 'Current Layer Alpha Only' view option. So you will have that 3.5 feature again when i send out the next version 4 build.

[Synthetik]

Here's a tip on working with alpha in v4.