how to compress or contract a clip

I want to reduce the clip's length by keeping the ratio of the image flow

I need to reduce the clip as a quicktime... so yes in a way it might have to do with speed contrôl.. like instead of having 100 frames in a 3 minutes clip, I may want 100 frames in a 10 second clip instead...

Welcome Alain to fcp.co

… the topic 'frame rates' can be confusing… so, the basics:
• a second is always a second
• a video/project has a fix frame-rate: 25 frames per second, 30, 60… whatever (keep rule #1 in mind!)
 • a source has its own frame-rate - 25/29.97/120 fps… (again: a second of that footage is a second long!)
• now, when you pour a 25fps into a 25fps timeline = a second is a second (you knew that), and speed is normal
• now you apply a 100fps to that project = surprisingly FCPX keeps a second a second (… the joke has some wear out, sorry…)
• but when you choose in the Retime Options /Automatic Speed, the 100 frames get spread over 4 seconds (4x25=100) = speed gets slow-moed
• … and vice versa: A 15fps source, set to Automatic speed in a 30fps gets speed-up by 2x

So, you can match the 'impression of speed' or match the framerate … but you can not vary the frame-rate within a project…

Savvy?