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Say I have some footage that is 30 frames long, and I want to to apply a mask to it via mix nodes that is 3 frames long. I need it to loop 10 times to cover all my frames. How do I do this in the compositor? If it's not possible in the compositor, can it be done in the sequence editor?

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  • $\begingroup$ What is your exact intention of using a mask? A mask of 3 frames repeated 10 times doesn't make much sense to me... Or are this just example lengthes? $\endgroup$ – Samoth Nov 23 '15 at 10:16
  • $\begingroup$ Maybe this helps? youtube.com/… $\endgroup$ – Samoth Nov 23 '15 at 10:22
  • $\begingroup$ It's just example lengths. $\endgroup$ – Drudge Nov 23 '15 at 21:52
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    $\begingroup$ Export your mask as a black and white image sequence. Re-import it as as an image sequence in the compositor and enable the Cyclic option. $\endgroup$ – cegaton Nov 26 '15 at 4:00
  • $\begingroup$ Yo Cegaton, you should put that answer into an answer. $\endgroup$ – Spencer Brown Nov 26 '15 at 4:13
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Let's say your setup on the compositor is like this:

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Unplug the input from the mix node and make the colors black and white and render the mask as an image sequence.

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And import them as an image sequence node:

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And use the sequence instead of the mask node.

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Make sure the cyclic and auto refresh options are enabled.

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The mask will be used in an endless cycle:

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The main disadvantage of this solution is that if you need to make changes on the mask's shape you have to re-export/re-load the images.

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A labor intensive solution would be to copy the keyframes for the mask.

Go to the Dope Sheet window and enable Mask Mode.

Then select the keyframes for the mask (press A to select all), duplicate them (ShiftD) and move them over on the time line (press G to move), duplicate again as needed to get as many iterations of the mask you need.

enter image description here

Even tough this solution seems a bit more tedious, editing and re-shaping the masks is quite easy. Also if you need to change the order in which the mask changes shape you just need to re-order the key frames.

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