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R
Ryan33535237wsjm
Participant
April 15, 2024
Question

Prores Alpha Channel Flickering in and Out

  • April 15, 2024
  • 1 reply
  • 892 views

I'm trying to work with a piece of stock footage that has an alpha channel, but I'm getting strange results in After Effects. It's mostly acting as though the footage has a black background with no alpha channel, but the alpha channel will flicker in and out briefly when I scrub through the timeline. This is flickering in and out is there even when I render the footage, and it doesn't seem to be consistent where and when it decides to show the alpha channel. Even zooming in and out on the composition window seems to cause the alpha channel to appear and dissapper. I've tried adjusting the interpret footage seetings, but to no avail.

 

Any ideas on a workaround or any other settings I could adjust?

 

The footage is ProRes 4444 , and I'm running AE 24.3.0 on 2023 Macbook Pro with Sonoma 14.4.1.

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1 reply

Warren Heaton
Community Expert
Warren HeatonCommunity Expert
Community Expert
April 15, 2024

Double-check how the Alpha is being interpreted (File > Interpret Footage > Main Options > Alpha).

If it was rendered originally from After Effects using the High Quality with Alpha preset, it should be Premultiplied - Matted with Color: 000000.

 

I'd try changing the how the Alpha is being interpreted.  If it's currently Premultiplied, try Straight.  If it's currently Straight, try Premultiplied.

I'd also try doing an Alpha Only render as an Image Sequence and, assuming that renders as expected (white reveals, black conceals), then ignore tha Alpha in the source and set the Image Sequence as a Luma Track Matte.

 

R
Ryan33535237wsjmAuthor
Participant
April 16, 2024

Thank you for the response. I experimented with the Interpret Footage settings and was unable to fix the issue. I ended up installing AE 23, and the footage looked a lot better. Still a few random black frames, but signifcaltly fewer than in the current version of AE. I exported the footage as a PNG sequence and just worked with that moving forward.

 

This appears to be some sort of a bug, as the results are inconsistent between AE versions and the frames seem to change randomly every time I scrub the timeline (or even resize the window).

Warren Heaton
Community Expert
Warren HeatonCommunity Expert
Community Expert
April 16, 2024

Creating a PNG sequence is a good workaround.


Which stock library does the clip come from? 

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