Hi, does anyone know how I can make an add-on for the Blender VSE to achieve any of these color changing effects?
vse cant do that imo , but you can import the video as an image plane and then use any kind of shader node magic on it … the last one for example is just a color ramp imo…
also this is the script release subforum … a mod should probably move this thread.
Is there a way to write an add-on with the necessary code to actually make it do this?
Hey !
I think the first step is being able to do it manually.
As said, I think VSE lack some filters for that, but yeah, shader nodes or compositor nodes could do that. Looks like the image is put through a coloramp and the values are shifted, giving the feeling of the light running through … Deluxe paint on Amiga got a similar feature IIRC.
In the end python can only help in automating the setup process here, that is taking the image and setup a nodetree / shader for that.
But the first step is to find the technique to render that effect, and latter look for automation with python. That will be quite straightforward at this point.
While it’s probably possible to make the whole filter in python by accessing the pixels value and modify them, it would be nearly impossible to put it back in the VSE, compositor or render output.
And it will be probably quite slow anyway unless a great deal of optimizations are done.
Python in general can’t do much more than automating things rather than create completely new features.
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Well this stinks… I was hoping it would be possible…
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It is possible. Read sozap’s post again. You just have to be able to do it manually first (using shader nodes) and then you can automate it in Python as an add-on
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But it’s not going to be in the VSE, is it? I can’t make a button in the VSE that can select the effect, and apply it to the selected video within VSE…
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That could be possible in a hackish way…
By creating a new scene and use that in place of the sequencer strip.
Maybe the shader option could be better to render it quickly and display using eevee/render preview in the sequencer.
All that said, to setup all that and get something working that’s a bunch of work, you really need to love that effect and use it really often to be worth putting all that together. But maybe some middle ground can be found to avoid to much scripting and too much manual setup.
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Well, this is great. I guess I’ll just wait until the VSE becomes a bit more flexible…
I also wanted to implement these effects in the VSE, but I guess that’s pretty much impossible as well…
You can implement any effect like this in the VSE by: making the effect using shader nodes, and then:
Ok ! cool ! 
But that could takes some time before it’s easier to do that in VSE !
Maybe at some point by applying compositor nodetree to a VSE strip, I could see that happening at some point, but in a far distant future…
Yes with python and without hack , I don’t think you can…
But by using VSE ability to play 3D scenes that should be possible. It’s a lot of work on the programming side tho…
You may look into simpler solutions like rendering these sequences and use them like stock footage in the VSE, it may be possible to adjust them a bit in the VSE like changing colors or adjust playback speed.
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So, at this point, there is no easy solution…
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your problem is just that you dont want to learn blender and instead use the vse which was never made for this … the second effect is probably easier to do in blender than in any other animation package , be it aftereffects or whatever
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Learn Blender? Eh, I got more than 6 years of experience, mate. You’re seriously telling me that I don’t want to learn Blender? I made the very first and only tutorial on how to use the Predecessor of Blender, called Traces. I know more Blender than probably most Blender users combined! The thing is, the VSE is the Video Editor. You can’t edit a video in Blender 3D workspace. Technically you can, but it just ruins the idea of using the Video Editor. I don’t want to import a bunch of images as planes, and just overlay each one on top of the other. Also, the Compositor stinks! It has been like this since it appeared! Slow and bloated! The VSE is perfect for video editing, and I want to continue that ease of use, but, here I am being told that I need to learn Blender. 
your op question seems like you are a complete noob though … 
Why’s that? Because I can’t program well?
Blender doesn’t have functionality for such effect in the VSE.
We have some modifers like: brightness/contrast, Colorbalance, Curves, Hue correct, White balance, and effect stips like glow, gaussian blur. We have also blender modes like: Hard light, overlay, Screen, Lighten, etc.
So far I think we cannot get that effect with those features here above.
And if I look at the Blender API > Sequence, there is not much more qua effects:
https://docs.blender.org/api/current/bpy.types.Sequence.html#bpy.types.Sequence
(check also subclasses)
So, it looks like we cannot achieve such an effect exactly.
But.
It’s possible to play with effects based on shadertoy or GLSL in a custom node-editor (that needs to be coded), render it out and then use it in your VSE. Or use a scene strip or something in the VSE.
Iyad worked on an add-on that could do that, but we lack time for further development for now. Here is an example of what it is capable of:
But such effects are not built in Blender. ( Though, maybe there is a way you can have that affect approximately with the features listed in the first paragraph. Do you have the name of the effect? )
The effects in the screenshot, are not provided by blender but is GLSL code.
And I guess we cannot code modifiers in the VSE, or any blend mode or any effect.