I needed a quick way to make a slideshow w/ transitions from a bunch of images so I put together a script w/ ffmpeg-python that does scaling/padding/cross-fading to generate slideshows like this video. Check it out: https://github.com/Twinklebear/ffmpeg-slideshow-py
GitHub - Twinklebear/ffmpeg-slideshow-py: Easily make a slideshow with crossfade image transitions using FFMPEG

Easily make a slideshow with crossfade image transitions using FFMPEG - GitHub - Twinklebear/ffmpeg-slideshow-py: Easily make a slideshow with crossfade image transitions using FFMPEG

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One interesting find was accelerating the pipeline by splitting out the slow image->video conversion step to run in parallel over the images and output a bunch of temp files. Then the fade/overlay pipeline runs on the videos which it can run faster on