Mask opacity issue?

[Col__McJeasy]

I'm a little rusty and kinda forgot how masking works..
I have a video of someone dancing and added another picture of someone to replace the dancer face.
To make it a bit more smooth, I've tried masking some parts within the picture layer. The problem is, the mask seems to be attached to the photo properties. So when turning off the opacity for the mask, it also turns off the picture, as if they are linked together. I've tried going to the start of the video and adding a keyframe for the mask, but even here, the opacity is linked to the picture transform properties. Sorry if this doesn't make sense, I tried my best explaining it.

[Martin_Ritter]

That's what mask opacity does.

What result do you want to achieve?

*Martin

[Col__McJeasy]

I want the mask>opacity and the transform>opacity to be in two different control groups.
I thought I could mask a part of he video and turn on the mask>opacity on only when it was required. The issue is that the mask opacity also controls the photo layer opacity as well, which I don't want.

[Roei Tzoref · Accepted solution]

mask opacity only makes sense when you have more than one mask... if you want to turn on and off a mask, and you only got one, there are several ways to do this.

one way is to add another mask at the size of the layer. clicking twice on the shape tool will do that. set it to "add" place it on top, the set all sub-sequential mask as "subtract" and play with the opacity.

another way is use an alpha matte: set a solid layer above the layer. place the mask there. set the bottom layer as alpha-invert matte, set the mask at the top layer as subtract and play with the opacity.

[Martin_Ritter]

And in addition to what Roei Tzoref​ wrote:

When you want a mask to switch on and off, you can use mask expansion and suppressed keyframes.

*Martin