ffmpeg -i in.avi -s 640x368 -aspect 640:368 -r pal -vcodec h264 -g 150 -qmin 25 -b 1000k -level 30 -loop 1 -sc_threshold 40 -partp4x4 1 -rc_eq 'blurCplx^(1-qComp)' -refs 2 -qmax 51 -maxrate 1450k -keyint_min 40 -async 50 -acodec aac -ar 48000 -ac 2 -ab 128k out.mp4
This preset is really good for SD content. Looks fine when I play it on my 20" iMac and looks fantastic on the iPhone too. Very little, if any, transcoding artifacts. I think for HD I will include some logic to determine if the file is indeed HD and, in that case, offer an option to encode to 720P and create an all devices version.