Issues generating transparent background with 3D Keyer

Hi,

I'm trying to output keyed footage with a transparent background for use in VJing software (i.e. I literally want a checkboard type transparency, which allows me to manipulate the footage flexibily later on). I'm using Resolve 17.

For this I'm using 3D Keyer. I'm able to key out the green screen very successfully, but no matter what I do I have issues outputting the transparency. I'm using ProRes 4444 so no codec issues. The issue is that my clips always have a black (i.e. not transparent) background, both on the Edit Page, and elsewhere. On the colour page when I connect the alpha channel output I get very strange results, too.

Am I correct in guessing that 3D Keyer somehow encodes the alpha channel back into a 3 channel file within the Edit page - i.e. when I connect the alpha output in Color page I'm not actually connecting anything?

I've also tried with Delta Keyer in fusion, with similarly frustrating results - again glitches when I connect alpha output on Color page.

I'm assuming there is something I'm doing wrong. I'm quite new to Resolve, so my apologies if this is really obvious stuff!

Thanks.

My first thought is, use the Chroma Key in Fusion for the Green Screen removal.

Hi. Thanks for your reply. I worked this one out eventually. You don't need to use Fusion, but you need to have a transparent layer underneath the clip (i.e. Resolve doesn't automatically assume a transparent background).

For reference, for anyone else trying this, I achieved this by either creating a solid colour and turning down the opacity, or - for doing this to a whole timeline, adding a duplication of the source node in the colour tab, and turning that duplication down. The result is videos exporting with the alpha channel intact, so long as your codec supports it. It's slightly clunky, but it works consistently!

Hi all,

I'm still having issues with this.
Here is what I'm finding.

- I want to export an asset with a transparent background. i.e. so I can import it into other software and take advtange of the transparency (or, for example, reimport into another DaVinci Timeline).

- There fore, I key the footage in either 3d Keyer or Fusion.

- I select the clip and go to the Color page, and 'Add Alpha output'. I wire up the alpha from the source to the node, and then the alpha output of the node to the alpha output

- Everything looks correct and fine, and I go to export with an alpha compatible codec (export alpha checkbox enabled), and then the background becomes this very strange grey thing... And the alpha export doesn't really work properly.

I've tried endless permutations of this, and *some* timelines with the exact same settings (as far as I tell) seem to work fine, but others don't.

Is there some sort of step by step guide to how to export with a transparent background in Resolve. Surely it's not that hard and I'm missing something very obvious?

Thanks!

Hi. Does anyone have any further information on this.

To reiterate:

I use the keyer in Fusion, which shows me a transparent background.

When I then try to export the final asset I lose the transparency, despite using an alpha compatible codec and choosing to export alpha.

Is this a bug, and if so should I report it?

Thanks!