Many thanks to your help but the aspect ratio don't change. I've tried different settings (blackbarcompensation -20 too) but the result is the same; only zoom and pan are affect, not black bars or, overall, aspect ratio. This is my setting:
<advancedsettings>
<skiploopfilter>48</skiploopfilter>
<slideshow>
<panamount>2.5</panamount>
<zoomamount>4.0</zoomamount>
<blackbarcompensation>-0</blackbarcompensation>
</slideshow>
</advancedsettings>
I've uploaded it with Filezilla in SFTP in /mnt/Scratch/Users/frontrow/Library/Application Support/XBMC/userdata/
I've tried without <skiploopfilter>48</skiploopfilter> too
The same photos with the ATV Apple Frontrow respect without settings the correct aspect ratio, but I would like use XBMC for all my media
Thanks again for your help