Resolution problem

[ChemicalFox]

Hi! I'm having a strange problem. For a ledwall with a resolution of 1440x288 I have made a series of clip having this resolution and create a composition in Arena of 1440x288 px.
Why all the clips are bigger than the output?
To play videos at the right size, I'm forced to put scale 50%, with a loss of resolution... HELP

PS in the input option of the advanced output i have selected all the area of the video, not only the centre. And this problem occour even with standard output or virtual device...

[AdevProjects]

Is there an effect on the whole composition or the composition scale that is scaling everything up by 200%?

To me from the screenshots it looks like this is happening:
Clip (scaled down 50%) -> Layer (normal) -> composition (everything scaled up 200%) -> Advanced Output (normal)

eg:

[ChemicalFox]

I finally found out the problem. There was the kaleidoscope effect (one of the 19 effects of this composition) with zoom 0.50. I was loosing my mind