View Full Version : Detective Lew investigates: File Sizes of avchd babies

Thomas Lew
12-07-2008, 12:05 AM
I had a peculiar hunch a few hours ago. AIC and ProRes files are known to be large, and I found myself wondering if their file sizes once rendered into a .mov will be likewise in comparison to each other in terms of file size. Pretty much, will ProRes footage which is larger than AIC footage stay proportionally larger once they are both rendered into a video under the same settings? Did I mention I am a scientist as well as a detective?


AIC footage (smaller than the other) -> render to .mov = Smaller file than the other

ProRes footage (bigger than the other) -> render to .mov = Bigger file than the other

The experiment:

Using the same 5 second avchd clip, I transcoded it into both AIC and ProRes formats. Then in final cut, I rendered each as a .mov with the SAME settings. My findings baffled and bewildered me.

The result:

AIC footage (124.6mb) SMALLER -> render as .mov = 6.2 LARGER

ProRes footage (165.mb) LARGER -> render as .mov = 5.8mb SMALLER


Ask dvxuser members for help!

12-07-2008, 06:29 PM
What are your export settings exactly?

01-04-2009, 11:28 AM
This is purely a guess ... but maybe because prores is a higher bandwidth codec it is keeping more information. This information might be helping the compression one way or another for making intelligent choices for compressing the video data.

Either way though ... you've got to give your exact export settings so that we can verify there were no errors in your method.