Using this page
https://www.reddit.com/r/ffmpeg/comments/17ma3mm/hdr_tone_mapping_not_working/

and our guide at
https://cinelerra-gg.org/download/CinelerraGG_Manual/File_naming_convention.html


I come up with this (working) line to put in file.opts for HDR to SDR
bt 709 100 nits mapping:

video_filter=zscale=t=linear:npl=100,format=gbrpf32le,zscale=p=bt709,tonemap=tonemap=hable:desat=0,zscale=t=bt709:m=bt709:r=tv,format=yuv444p

But it only works with software decoding. At, like, 2.3 fps for full 4k frame.

And also you need to compile your ffmpeg used in cingg with z.img library.