long video
1. optimize source loop
ffmpeg -i w.mp4 -f lavfi -i color=gray:s=1920x1080 -f lavfi -i color=black:s=1920x1080 -f lavfi -i color=white:s=1920x1080 -preset veryslow -crf 51 -filter_complex threshold w-bwt_vslow_crf51.mp4
2. concatenate loop
for f in *.mp4 ; do echo file \'$f\' >> fileList.txt; done
&&ffmpeg -f concat -safe 0 -i fileList.txt -c copy merged.mp4
3. zoom (x.xxx is 2.13-1/totalframecount)
ffmpeg -i merged-1h.mp4 -vf "scale=w=(1920*4):h=(1080*4), zoompan=z='min(pzoom+0.000012708,2.13)':d=1:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)':s=192x108" merged-1h-zoom.mp4
sources: