I think MusicVid's advice on a couple of settings is the best solution.

Alternatively, the SEMW autolevels plugin is free and does a decent job with exposure and white balance but you don't have much control over what it does: https://www.semw-software.com/en/autolevels/

@Musicvid @RogerS

You misunderstand. I did not record these videos nor do I have any control over the environment in which they were or will be shot. I just get to edit them.

Advise remains. Make two or three correction presets and don't sweat the rest.

Is there a plugin available that can dynamically alter the gain/levels or similar based on monitoring a patch on a video?

I've got a few videos that were recorded in a sunny room during a partly cloudy day and the lighting is changing every once in a while.

It's difficult to search for that info in google or explain what is meant even though I know exactly what you mean. When I tried to search for such a plugin, my problem was auto exposure being on in camera, aimed at at an area in shadow but as people walked infront of camera who were in sun, exposure kept changing. What would be needed is a filter that measures illumination level where you manually mark and keeps it within a certain range. With 8bit color this has the potential to look terrible but maybe through some sort of artistic expression a shot could be saved.

I have to think such an effect exists, as many others would have experienced a similar problem

Yes, it probably exists, is certainly very expen$ive, is ungodly slow, and gets it right about 40% of the time without manual intervention on a good day. You're talking about unbaking a cake, not a straightforward math problem..

I don't know how well they work but Premiere has Auto Levels and Resolve has Color Stabilizer. These are builtin, not 3rd party plugins. I had a quick look at color stabilizer, but I don't have any media currently to test it with. If anyone does know of a plugin that works with vegaspro please comment.

Is there a plugin available that can dynamically alter the gain/levels or similar based on monitoring a patch on a video?

I've got a few videos that were recorded in a sunny room during a partly cloudy day and the lighting is changing every once in a while.

 

It's difficult to search for that info in google or explain what is meant even though I know exactly what you mean. When I tried to search for such a plugin, my problem was auto exposure being on in camera, aimed at at an area in shadow but as people walked infront of camera who were in sun, exposure kept changing. What would be needed is a filter that measures illumination level where you manually mark and keeps it within a certain range. With 8bit color this has the potential to look terrible but maybe through some sort of artistic expression a shot could be saved.

I have to think such an effect exists, as many others would have experienced a similar problem

I think you misunderstood the responses. Both of us recommended solutions to use in Vegas, not in camera- the presets would be curves or levels Fx to grade your scenes (for example: dark, light, middle).

Did the autolevels plugin I suggested above not work for you? Do give it a try and see what it does.

Realistically though I don't see a way to have this work well- the best case is to mitigate how bad it looks, probably by brightening underexposed footage and darkening the subjects until they are a reasonable brightness in the too bright scenes (even if the backgrounds are clipping to white).

This is an example of davinci auto color stabilizer. It's not the same situation as the poster, but it is tracking a section on the back wall and changing the brightness if it detects a change in illumination. In this example the person is using a camera with extra sensitive auto exposure, to the extent that you see noticable lighting and darkening on the back wall as he moves. After the filter is added the problem is much less obvious so I feel if Poster could get a plugin for vegas it could be effective and be much less work than constantly manually keying the exposure each time the sun comes in and out of clouds

@Musicvid @RogerS

@Former user Lenard has the best understanding of my situation. It's not worth it for me to animate levels changes during the short video I'm working on currently. The time needed just isn't justified. Coming from the 3D development world I know this sort of thing is not only possible but computationally cheap and I was hoping someone had done it and I could add in just a little bit extra to make the resulting video a bit better. It's also not worth it (yet) for me to dive into plugin development for Vegas but that day may be coming.

Also understand that the video was recorded using Zoom so the quality isn't great to start with and any artifacts would, almost literally, be lost in the noise.

There are two methods I found that work within Vegas.

Boris Sapphire has a Flicker Remove effect that works pretty well and evens out the levels without too many obvious artifacts. Unfortunately it looked like it would take some tweaking to make the visual result worth it so I started digging in the other Boris tool that I just recently received.

Boris Silhouette has a Deflicker effect that gives near-perfect results. The drawback is that it's an external tool and the footage has to be exported to an image sequence, processed and re-imported. Odd to me but my understanding is the tool is primarily used by big studios and that's their process. For the short (5 min) video I'm working on currently, that's not an impediment.
 

I'll have to give Resolve a shot since it gets mentioned a fair amount. Probably worth being passably familiar with.

@michael-harrison

This may be a long shot depending on the period of the changes.

GBDeflicker

Though it is marketed as an Adobe plugin, there is a standalone Windows version that operates on still image sequences. No big deal for time lapse shooters, but you would have to render your troublesome source to still image sequences and back to video. There is a free trial and the price is reasonable.