Blackmagic Forum

Can someone explain why is this happening?
(see the attached GIF)

It seems like the more merges I have - the longer it takes to render PROGRESSIVELY
All the merges have "Flatten Transform" checked and both FG and BG connected, shifted animated center and animated mask that limits the FG (makes a hole in the FG where you can see the BG), basically like a clone stamp in Photoshop.

Please advise on what is going on. Haven't had this problem with Eyeon Fusion 5, 6

Fusion Studio 9 build 13

grouped merges by 4 max and combined them in parallels

render time dropped from 2 minutes/frame to 2.5s/frame

on the initial GIF you can see how Fusion renders the same merges over and over again instead of going sequentially one after another. So the last few merges don't get rendered until the first ones are recalculated like a million times.

Can someone please explain to me why this happens and why this workaround worked?

This kind of repetition does not make any sense in serial graph. Graph should be evaluated so that each node first calls its inputs and then executes itself, so in brute force mode (no caching) each node and its subtree would be called as many times as it has attached inputs from other nodes. But in your node graph each merge node has at worst only two inputs attached. Why it does what it currently does... no idea.

So it happens when all the masks come out of the frame.
Animating Blend on Merges to zero at that moment fixes the issue.

Hi Tengo
You mentioned Fusion 9 build 13.
Did you try the latest Fusion 9.02, not sure if
build 13 is same as 9.02.
I'm on a Mac with 16 GB.

Yasir.