String formatting for read input of imovie (OSX)

Hi. I'm wondering if anyone knows why, when trying to use read $1 with a sprintf as it's input. The sprintf in turn has three inputs,

%s%id%s

where the first %s is the absolute path, the %id is an int and the second %s is the extension (.mp4).

This prints out the correct file URI, for instance

imovie: can't find file /path/video_1.mp4

but the file isn't found. Any idea how to make this work?