MPEG 1 size anomaly?

PeterWright wrote on 6/5/2005, 11:49 PM

I rendered some widescreen footage to include on a CD rom, but it turned out to be too big at 720 Mb.

So, I reduced its frame dimensions to two-thirds the original size (720 x 406 down to 480 x 270), which is less than half the original area, but the resulting MPEG1 file was still the same size at 720 Mb. I'm confused!

Comments

Liam_Vegas wrote on 6/6/2005, 12:00 AM

The size is purely a factor of the bit-rate used and nothing whatsoever to do with the frame size you choose.

However.... for a given frame size... the quality of the video produced IS a function of the bit-rate.

What you should have done... is reduce the bit-rate as well as reduce the frame size.

PeterWright wrote on 6/6/2005, 12:21 AM

Thanks Liam - I knew there had to be an explanation! So the smaller frame with the same bit-rate would have been less compressed and therefore higher quality.

As quality isn't an issue here, I'll go back to the original frame size with lower bit-rate.

Thanks again.