I’ve created a complex split filter that crops a 1372 x 1372 input source into multiple unique tiles, and overlays them in a single output. It works exactly how I want, except that I am unable to output to a new frame rate:

ffmpeg -i test.mp4 -filter_complex "[0:v]split=5[s1][s2][s3][s4][s5];
[s1]scale=377:377,crop=360:360:2:2,pad=1920:1080:1560:720[bg];
[s2]crop=1372:1068:0:0[s2];[bg][s2]overlay=0:0[bg];
[s3]crop=460:308:0:1064[s3];[bg][s3]overlay=1372:0[bg];
[s4]crop=460:308:456:1064[s4];[bg][s4]overlay=1372:308[bg];
[s5]crop=460:308:912:1064[s5];[bg][s5]overlay=1372:616" -framerate 20 output.mp4

This does not actually change the framerate — it only honors the input source framerate. I’ve tried integrating the fps into the filter complex, but nothing I do works.