activityAq property

When true, the encoder estimates each MB's 16x16 luma variance and routes low-variance MBs (faces, skin, smooth background) to segment 2 with delta aqSmoothQiDelta (default -8, sharper) and high-variance MBs (heavily textured detail) to segment 3 with delta aqTexturedQiDelta (default +4, coarser). Mid-variance MBs and any MB also claimed by roiRect keep their existing segment (segment 1 for ROI takes precedence over activity). Net effect on VC content: faces look noticeably better at the same total bitrate. Default false keeps existing behaviour byte-identical.