Fusion & Edit Page Prerenders

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gabe67

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Fusion & Edit Page Prerenders

PostMon Jun 07, 2021 10:43 am

When I apply a key to greenscreen in Fusion the result is pre-rendered. I have the option to render Fusion output selected. However, as soon as I change the sizing and positioning in the Edit tab, the whole Fusion effect would render again. This is very time consuming. Is there any way to do this without triggering a full re-render in the Fusion tab?

As a side note, color effects don't seem to affect the Fusion Prerender.
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Jim Simon

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Re: Fusion & Edit Page Prerenders

PostMon Jun 07, 2021 2:59 pm

Try the new Render in Place feature for the Fusion comp.
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Ryan Bloomer

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Re: Fusion & Edit Page Prerenders

PostMon Jun 07, 2021 6:44 pm

render and replace takes sizing and positioning information on the edit page. I've made a feature request for what you are running into, ideally you could choose what your render in place command does:

If you have a 4k clip in a 1080 timeline, Resolve will honor the 4k clip resolution in the fusion tab.

What'd be great is when you render in place, you choose what happens:
1. Render Edit size with scale and position - this would be a 1080 clip that matches the timeline position and scale
2. Render fusion size and keep attributes - this would be a 4k clip that matches the timeline position and scale through the transform properties

One way around this, is to temporarily make your timeline the same size as your Fusion clip source, use render in place so it honors the larger resolution, then change the timeline back to 1080
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gabe67

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Re: Fusion & Edit Page Prerenders

PostMon Jun 07, 2021 9:30 pm

Thanks for your replies.

It's actually mostly talking head - just moving him/her a bit from left to right already triggers a re-caching. I tried render in place but in this case it's not working and destroys the alpha channel. Even so when rendering in ProRes4444 which has worked before in another project. It creates a weird halo around the person (see screenshot).
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Ryan Bloomer

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Re: Fusion & Edit Page Prerenders

PostThu Jun 10, 2021 12:21 pm

When you pre-render with alpha, is there actually an alpha?

One thing you could look at doing is caching your media out node in the fusion tab, so that the heavy lifting as already done for the edit page. When using this approach, you'll still need to re-cache on the edit page any change you've done, but it's only caching the prerendered frames.

I haven't tried render in place with alpha in a while, but I know in 17 beta I was running into the weird unmultiplied alpha with DNxHR 444 like you are with ProRes.

You could also try rendering the clip through the delivery page with alpha, and conform back to the timeline. I know it's not as convenient but I have found it as a great way to batch processing for similar approaches you are doing. If you use the delivery page for batch processing, utilizing the "Reconform from Bins" feature is extremely powerful. This is how I've started to do this process if I need control on the edit page after keying.
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Hendrik Proosa

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Re: Fusion & Edit Page Prerenders

PostThu Jun 10, 2021 12:44 pm

This looks like the problem with Resolve alpha handling that pops up in various situations. Bright outline is symptom of unpremult operation and my impression is that it is done erroneously once or even twice too many. What the root cause is, don’t know but since it comes up in different situations, it seem to be something in general processing engine, some parts maybe expect premulted values and others unpremulted and in some cases mismatch happens.
I do stuff.
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gabe67

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Re: Fusion & Edit Page Prerenders

PostThu Jun 10, 2021 8:59 pm

Thank you for your replies. Reconforming from bin seems like a nice workaround. I am actually using fusion output caching that’s why it’s so weird that anything in the edit page trigger a full rerender.
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chrisbrearley

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Re: Fusion & Edit Page Prerenders

PostWed Jun 23, 2021 9:17 pm

I have had an absolute nightmare today with Fusion output cache.

Sometimes it wants to recache when I am in the colour page. When doing so sometimes it grinds to a halt forcing a restart and then when I do, a lot of cache is missing which then has to rerender. Really poor playback performance when it is cached despite caching to an m2 SSD whatever type of file I cache to. Some shots also take ages to track in the colour page - it's as the the tracker is looking at the Fusion comp and not the cached stuff.

Been years now since the Fusion tab was implemented and it's still isn't production ready when doing heavy lifting. Render and replace is probably my next play but that's not a particular slick workflow when it comes to making tweaks.

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