We have a dance competition approach and the song we've chosen is 3:54. The rules say the song cannot be more than 3:30. We have to provide copies of the song on a CD, a USB stick and an iPod/iPad/iPhone which means we cannot rely on realtime slow-down software on an iPhone alone to make the tempo adjustment.
We must record it and save it as a new file and then copy it to all the medium.
I have a friend with a Mac who is willing to alter the file for us -- what does he need to do to change the tempo of the song so it fits in to the 3:30 run length requirement?