Here is how to record a movie with a static background image. The idea is to record all the movie frames with transparent background and then overlay those on a static background image during the movie encoding. Here is an example rotating an atomic structure in front of a static image of the cryoEM map used to determine that structure. Make a directory on your Desktop called “movie” to save the image frames. Then use these ChimeraX commands
open 8of8
movie record dir ~/Desktop/movie transparentBackground true format png ; turn y 3 120 ; wait 120 ; movie stop
open 16850 from emdb
save ~/Desktop/movie/background.png
To combine the transparent image frames and the background into a movie I’ll use the ffmpeg movie encoder that comes with ChimeraX in a shell window on a Mac.
$ cd ~/Desktop/movie
$ ~/Desktop/ChimeraX-1.8.app/Contents/bin/ffmpeg -loop 1 -i background.png -i chimovie_Umkk-%05d.png -filter_complex overlay=shortest=1 movie.mp4
This ffmpeg compositing command is explained here.
Tom Goddard, October 8, 2024