Timing of masks

[TpFrontRow]

I am fairly new to Arena and do have a chunk of it figured out however, one thing I have not yet been able to figure out is....
I am working on a projection mapping sequence using 2 projectors. I've got an output mask figured out for the irregular surface we will be projecting onto. However, at one point in a 90 second sequence, I need to add a mask for about 15 seconds only in order to "hide" something happening.
How can I time the appearance of the mask so it comes on and goes off at the right time?

[Zoltán]

you can't switch advanced output masks on /off automatically.
but there are several ways to accomplish this, here are some examples

- rendering the footage with the mask integrated in the timeline
- timing solid colors in a layer and using the built-in auto pilot feature to switch to the black. The way I would do this is put a solid color in the same column as your video on a layer outside the composition canvas, create a slice in the correct area, input from this layer - this will be your mask-, set the duration of this solid to what delay you need (40 000 msecs for 40 seconds for example), switch on auto-pilot - play next clip, then in the next column place a black solid color, and launch the first column video+timer. The mask layer opacity should be at 0% and Input Opacity unchecked in the slice settings. and place an 'ignore column trigger' clip in the video layer in the same column as the black solid - just in case you would want to launch the mask with a column trigger manually or externally.
- Use an external program like this one to do and edit the timing easily of the black solid in a layer routed to a slice instead of the off-screen solid.

[TpFrontRow]

Thank you.
I'll try this out