int $firstFrame = 25;

int $lastFrame = 100;

 

 

int $startFrame = 5;

int $numFrames = $lastFrame - $firstFrame + 1;

 

 

if (frame < $startFrame)

file1.frameExtension = $firstFrame;

else if (frame < $startFrame + $numFrames)

file1.frameExtension = $firstFrame + (frame - $startFrame);

else

file1.frameExtension = $lastFrame;