What is the difference between 1080p and 1080i? What does it mean?

+1 vote
asked May 14, 2012 by Studio66Designs (421 points)
What does 1080i mean? What is the difference between 1080p and 1080i?
commented May 14, 2012 by AlwaysLearningTech (131 points)
Questions like this should be asked often.

3 Answers

0 votes
answered May 14, 2012 by Jackster1337 (8,481 points)
In video there are lines of pixels.

P is refreshing from top to bottom.

I is every other line being refreshed top to bottom.
commented May 14, 2012 by Studio66Designs (421 points)
So what will the difference be if I upload a video in 1080i to YouTube instead of 1080p?
commented May 14, 2012 by Jackster1337 (8,481 points)
It is just how the image is shown.
YouTube converts to P
commented May 14, 2012 by Studio66Designs (421 points)
But why is there an option on Sony Vegas for 1080i? I don't understand if YouTube just converts it to 1080p?
commented May 14, 2012 by Jackster1337 (8,481 points)
Sony Vegas is not just for YouTube...
0 votes
+5 votes
answered May 14, 2012 by sfrancis928 (2,716 points)
P stands for Progressive. I stands for Interlaced.

1080p is 29.97 frames every second. 1080i is 59.94 fields every second. There are two fields, an upper and a lower. Each field is half of a frame, containing every other line of the frame.

![alt text][1]

The problem with recording interlaced is that when something is moving, two fields that are supposed to line up will be offset. The camera will read the first field, then something moves, and the next field will be different:

![alt text][2]

So 1080i is basically 1080p, but with motion issues. I never shoot interlaced, progressive is the way to go. Interlacing was needed years ago when they didn't have enough power to get enough progressive frames per second, but it's pretty much useless now. I don't know why it's still used. So when you have a choice, choose 1080p. You can read more into it but that's it in a nutshell.

  [1]: /upfiles/L0185_InterlaceExample.png
  [2]: /upfiles/Interlaced_video_frame_(car_wheel).jpg
commented May 14, 2012 by catchatyou (20,719 points)
I think you've explained this pretty well (even though I already know what the difference is).
commented May 15, 2012 by sfrancis928 (2,716 points)
Thanks a lot!
commented May 15, 2012 by conspiritech (41 points)
interlace causes issues sometimes with apocryphal/artifactual lines in the editing programs.  i would avoid it.
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