FORUMS: list search recent posts

What does "key frames" do?

COW Forums : Apple Final Cut Pro Legacy

<< PREVIOUS   •   FAQ   •   VIEW ALL   •   PRINT   •   NEXT >>
piff aroni
What does "key frames" do?
on Jul 12, 2010 at 1:40:53 am

I am bouncing a video using compressor and was wondering, what does they KEY FRAMES do? it has automatic, every, and all.

for a 24p video posted on youtube, what should these settings be? What does frame reordering do?


Return to posts index

Michael Sacci
Re: What does "key frames" do?
on Jul 12, 2010 at 2:00:34 am

with compressor, key frame is a full frame, if you don't understand them it is always best to use auto.

the more you have the better transition maybe but you may cause the compressor to be softer overall.


Return to posts index

Rob Grauert
Re: What does "key frames" do?
on Jul 12, 2010 at 2:02:58 am

A Key Frame is a fully encoded frame of video.

There are 2 kinds of compression (i think there's only 2). They are Long GOP and Intraframe (or I-Frame). Key frames relate to Long GOP.

Long GOP stands for long groups of pictures. These groups of pictures share data with one another. In other words, in order to compress the video to a smaller file size redundant data across multiple frames can be tossed out, but it will find that data from another nearby frame. That nearby frame is the key frame.

More frequent key frames results in a larger file size, because there are more frames that contain all the data they require.

I usually set the key frames to automatic, but if that doesn't work try every 300 frames. If that still doesn't work try 150.

Make sense? If not, do some research on Long GOP vs I-Frame compression.

Rob Grauert, Jr.
http://www.robgrauert.com
command-r.tumblr.com


Return to posts index


piff aroni
Re: What does "key frames" do?
on Jul 12, 2010 at 2:31:11 pm

Thanks for your reply but it still does NOT make sense to me. I am looking for the best quality to be placed on youtube. I have recored my video at 24p and removed the pulldown.

my video is only 4 min music video. what would be the best settings?

also, what does the option FRAME REORDERING do?


Return to posts index

Matt Lyon
Re: What does "key frames" do?
on Jul 12, 2010 at 7:40:14 pm

If you search the forum you'll see that this question has been answered a lot. You can also look on the YouTube help pages and they have guidelines for compression settings.

"Frame Reordering" enables B-Frame compression (Bi-direction Predictive Frames, IIRC). Usually you will leave it on, but certain software or hardware is happier with B-Frames turned off. I think YouTube used to recommend disabling B-Frames, but I'm not sure if that is still true.

Matt Lyon
Editor
Toronto


Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2017 CreativeCOW.net All Rights Reserved
[TOP]