Size of Quicktime Exports – Quality and Percentage settings

[Guy Burns]

I have a source file of ~250MB, HD, running at ~30Mbps. It's on a Premiere timeline, and I want to export it as a Quicktime file for insertion into Keynote. I want a smaller file because Keynote doesn't reference files, it imports them. And I want to reduce the Keynote file-size.

So I did some file-size tests, all h.264, changing the Quality settings…

100% – 547.5 MB

75% – 86.3MB

60% – 38.2MB

50% – 22.3MB

Not what I was expecting. I did some quick maths, and the relationship is higher than cubic. i.e. halve the percentage, and the file size is less than 1/8.

This Percentage figure which can be adjusted in the Quality setting – percentage of what?

[R Neil Haugen]

Personally, I would not expect the percentage to be resultant file size. I would expect it to be some variable measure of the resolution or image quality.

And the needed bitrate depends so much on how much fine detail and how much movement is in the image. The less of either/both, the more compression before it gets too objectionable.