Convert project 50 frames per sec. in 25 frames per sec.

[jbaguette]

Hello,

I have a project Generic OHCI SD Pal currently 720x576 50p 4:3 50 frames per sec. I want to convert Generic OHCI SD Pal 720x576 50i 4:3 25 frames per sec.
How this change?

Thank you in advance