You need to crop your song to remove dead space at the end, which iPhoto reads as music. It matches the slides to the whole "song" so you have "extra" slides at the end of your show.
Here's how to do it:
1) Go back to iTunes and select the song you want to use. Just highlight it.
2) Go to the File Menu at the top, and under that choose "Get Info".
3) This brings up an interesting window. Choose "Options".
4) Start Time is probably OK unless there is something at the start you want to remove. Otherwise just leave it unchecked.
5) Stop Time is the time the recording actually stops. Play the song and watch the timer at the left of the progress bar, and you will usually see that the music stops but the timer continues for a little while. This is dead space. Note the time that the music stopped and enter that in the previous window in the Stop Time field. Since the Stop Time field can be very exact, you can keep fine tuning to the thousandth of a second to get it exactly right, if you need that much precision, and it's simple to do. The closer you get to the end of the last note the better but don't clip it off.
6) Now in order to get iPhoto to use that time for your synchronized slideshow, it isn't enough to use that cropped song in a playlist because iPhoto still plays the uncropped version that was too long.
7) Burn your cropped song to a CD and then import it back from that CD and it will be exactly the right length to fit to your slideshow without any extra slides or ken burns movement at the end. Use the import button, don't just drag the song to your library.
Nothing is deleted when you crop a song, the playback time is just shortened. If you want it back the way it was, just re-enter the old Stop Time or just delete the new time. I noticed that sometimes there is as much as 9 seconds of dead space on some songs. Sometimes it's only a second. I guess it depends on how they were recorded.
It's all a lot easier than it sounds.
Do this before you burn your slideshow onto a DVD. Export your slideshow to QuickTime, not iDVD, direct it to your Movie folder then play it and if everything is synchronized burn it with iDVD or Toast.
Don't forget that if all else fails quit iPhoto and go to your Library..Preferences...apple.com.iPhoto.plist and delete it. A new one will be created when you restart iPhoto. Then recheck your settings and try again. A new .plist fixes a lot of stubborn quirks.
From what I have read here, sound not synching in slideshows is the biggest frustration in iPhoto.
Cheers
20" iMac G5, iMac G4, iBook G4 Mac OS X (10.4.6)
20" iMac G5, iMac G4, iBook G4 Mac OS X (10.4.1)
