The below are two single-line commands to encode a high quality mpeg file ready for writing to a DVD disk.
PAL Fullscreen
mencoder -of mpeg -mpegopts format=dvd -srate 48000 -ofps 25 \ -ovc lavc -oac lavc -lavcopts vcodec=mpeg2video:\ vrc_buf_size=1835:\ keyint=15:\ vrc_maxrate=9800:\ vbitrate=4900:\ aspect=4/3:\ acodec=ac3:abitrate=192 \ [input].avi -o [output].mpg
PAL Widescreen
mencoder -of mpeg -mpegopts format=dvd -srate 48000 -ofps 25 \ -ovc lavc -oac lavc -lavcopts vcodec=mpeg2video:\ vrc_buf_size=1835:\ keyint=15:\ vrc_maxrate=9800:\ vbitrate=4900:\ aspect=16/9:\ acodec=ac3:abitrate=192 \ [input].avi -o [output].mpg