does your hw support av1 _encoding_ ?

No! I probably should have checked that first !

I do not think cingg as-is uses this specific *binary* - it does not copied around into bin and there is no link failure ... I think only non-ffmpeg mpeg2 encoder uses this feature

Will put in patch and if some genius comes along, they can fix it. I am quite sure that this is non-ffmpeg rendering of mpeg from the original Cinelerra version when ffmpeg was not even a thing. But I still use it for creating DVDs and users with old VHS tapes could certainly benefit if y4mdenoise was integrated.