Modify value after "-crf" command in mme_pipeCommand cvar ("ffmpeg -f avi -i - -threads 0 -preset ultrafast -y -pix_fmt yuv420p -crf 23 %o.mp4 2> ffmpeglog.txt").
Lower value - higher quality and bigger size.
You won't notice differences with value less than 17. 0 - lossless compression...