- Posts: 5
- Joined: Wed Apr 12, 2023 1:47 pm
- Real Name: Dave Young
Wed May 01, 2024 11:11 am
I ran into a strange issue today, and eventually solved it - but couldn't find anything about it on the forums or via google. So, I'm sharing my experience and how I solved it so that others can find this (and if I forget I can too! 
).
TLDR: If using a render cache format that doesn't support alpha (e.g. ProRes 422), avoid using node / colour caching on clips that involve any transparency, or effects that use transparency.
What I was experiencing:
"Render Cache Colour Output", and "Node Cache" were both introducing a colour shift in my footage. I had multiple lighting effects in series on a PNG file, with animations, on the colour page
E.g. The blue colourisation effect from a 'Light Rays' effect wasn't working properly after caching had been performed - it now looked green. Various effects on another clip's text just simply weren't applied.
I also had some bizarre text glitches, where black lines appear flickering across text, and blurs produce a series of 'bubbling' solid circles.
What it was for me:
I had a render cache format selected (ProRes 422) that does not support alpha!
I disabled the node caching, and the colour caching, and left the caching to be done on the edit page. After doing that, all my troubles floated away.
If anyone has thoughts on this matter I'd love to hear them. It seems to me that whilst this makes sense, the behaviour from a user perspective is perplexing and it could be signposted much better - it seems non-ideal for it to 'fail silently' in this way, resulting in head scratching whilst grappling with bizarre glitches on text (that bubbly effect), or effects simply being dumped.
Remember: If you use a format that doesn't support alpha, and then try and cache your nodes or colour output, you're gonna have a bad time.
). TLDR: If using a render cache format that doesn't support alpha (e.g. ProRes 422), avoid using node / colour caching on clips that involve any transparency, or effects that use transparency.
What I was experiencing:
"Render Cache Colour Output", and "Node Cache" were both introducing a colour shift in my footage. I had multiple lighting effects in series on a PNG file, with animations, on the colour page
E.g. The blue colourisation effect from a 'Light Rays' effect wasn't working properly after caching had been performed - it now looked green. Various effects on another clip's text just simply weren't applied.
I also had some bizarre text glitches, where black lines appear flickering across text, and blurs produce a series of 'bubbling' solid circles.
What it was for me:
I had a render cache format selected (ProRes 422) that does not support alpha!
I disabled the node caching, and the colour caching, and left the caching to be done on the edit page. After doing that, all my troubles floated away.
If anyone has thoughts on this matter I'd love to hear them. It seems to me that whilst this makes sense, the behaviour from a user perspective is perplexing and it could be signposted much better - it seems non-ideal for it to 'fail silently' in this way, resulting in head scratching whilst grappling with bizarre glitches on text (that bubbly effect), or effects simply being dumped.
Remember: If you use a format that doesn't support alpha, and then try and cache your nodes or colour output, you're gonna have a bad time.