video recording

I just got the new iPad. I want to record speaking tests in my classes, but the 1920 x 1080 format is much too large.

Takes up way too much memory. And, I am primarily concerned with sound quality, not picture quality.

Is there away to change the setting to record in 640 x 480, or smaller?

a) I believe I could do this using the rear facing camera, but I do not want to do that.

b) I know I could reduce the file size later on my big iMac, but that is too time consuming.

Thanks.