I do not use qdvdauthor, but here is what I do.
I use the mplayer mencoder mf:// utility to create a mpeg2 slideshow movie of the jpeg photos. Then I use dvdstyler to generate a DVD iso with menus etc. Here is an example mencoder command which also adds a soundtrack, produces a 4/3 disply aspect ratio, and displays 1 jpeg every 5 seconds (fps=1/5.
Code:
mencoder -audiofile <snd file path> -oac lavc -af lavcresample=48000 \
-ovc lavc -of mpeg -mpegopts format=dvd -vf scale=720:480,expand=:::::4/3,harddup \
-mf fps=1/5 -srate 48000 \
-lavcopts vcodec=mpeg2video:vrc_buf_size=1835:vrc_maxrate=6000:vbitrate=2500:keyint=18:trell:mbd=2:precmp=2:subcmp=2:cmp=2:dia=-10:predia=-10:cbp:mv0:vqmin=1:lmin=1:dc=10:acodec=ac3:abitrate=192:aspect=${aspect} \
-ofps 30000/1001 -o <out mpeg2 file> mf://*.jpg