addressed How do you change the speed of a clip but not the duration

[ADINFO1]

I have a video clip of the beach with moving ocean water.  I have figured out how to change the duration of the clip to make it longer but it severely slows down the speed of the water.  How do I change the duration of the clip and maintain or speed up the movement of the water?

[borate]

There's only so much video.  If it's stretched with a speed change, the content will become slower.

Instead, loop several copies of the same clip at normal speed (place one after the other) and see if that does the job.

[Nationalsolo]

Hi

"......How do I change the duration of the clip and maintain or speed up the movement of the water?......"

Simply put, you can't.

You can shorten the clip duration but the motion will speed up. 

You can lengthen the clip duration but the motion will slow down.

The correct answer to this is to film enough in the first place.

That's the bottom line. Borate's solution is the only way. Add the clip to the timeline and then add it again so it follows itself. Trim the end of the first clip so the motion between the clips (if it is cyclic)  is properly synchronized Do this in such a way that the movement over the join is undetectable. (Never easy.)  If you can't get this exact then add a very short crossfade effect. Now trim the end of clip 2 so the whole sequence is the length you require. It will play at normal speed for the duration you require.

Whether or not this is successful will depend to a great extent on the contents of the clip. It's often been used in films where, for example  the incoming tide washes out titles drawn on the sand or when reversed runs back out to reveal titles etc. Obviously a background boat or person in the shot that continually walks or moves forwards and backwards repetitively would rather spoil the effect. If it's just the ocean you may be successful.

Nat