Somebody asked how I make videos with Gimp.

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What I do is make an animation, mostly in a fractal program, then export as a series of PNG's often around 1,000.
Often I re-process them with the stand-alone G'MIC and look at the command in a terminal. Then I paste the command into a batch script and run it on the PNG image stream. I use the same method for some GEGL filters. Gimp and GMIC are not good at animation streams. Gimp can open 1,000 images @1080p and 'show animation' if you have enough ram.
Warning. Never select a large number of layers/images and 'open' in Gimp. Always 'Open as Layers'. You could scramble your filesystem by opening many instances of Gimp.


When I have a bunch of image series (I use PNG's because they have an alpha channel) I assemble them into a video currently using Davinci Resolve free version. This is a video editor and it can do the things Gimp and GMIC cannot do. Things like transitions and fade-ins-outs. I can do this with GEGL but it is way too fiddly to use compared to a video editor.

If you put the audio in first you can easily sync your image streams with the audio or the other way around if you are using a mic. Resolve needs at least 32 gig of ram to function properly and a high-end graphics card is needed. (Resolve also needs conversion of mp4's and mp3's to WAV and MOV)

So it's a complicated process that also uses python scripts for exporting and alpha channels etc.
With the last video I put the audio at the base, then a creative commons video stream of coastline next and then the clips above.

There is a technique to put an animation series in twice, exactly on top of each other but with the streams colored differently. They are transitioned using fade-ins or making part of one alpha. In my last clip I used GMIC 'waves' distortion on a fractal series that worked well. Resolve can also do effects like that.