in the mencoder documentation about xvid encoding i found an option
"hq_ac Activates a better coefficient cost estimation method, which
slightly reduces filesize by around 0.15 to 0.19% (which corresponds
to less than 0.01dB PSNR increase), while having a negligible impact
on speed. It is therefore recommended to always leave it on."
Can i find something like that in ffmpeg too? Could it be "-coder ac"?