Welcome to quick and dirty tutorials.
In this tutorial you will learn a basic understanding of how interlaced NTSC video works, why you
might not see all your interlaced video frames accurately in Final Cut Pro, and how to fix
the problem.
Alright, let's get started.
When you record footage with a camcorder that uses interlaced video technology, it doesn't
capture each video frame once as, say, a Hollywood camera does.
Instead, each video frame is broken down into two fields, with each field containing half
the total lines of resolution in each frame.
On the top is an example of what a film camera frame would look like.
On the bottom is an example of what a video frame would look like.
Not much difference at first glance, I know.
Let's take a closer look at that video frame and break down what's going on, keeping in
mind that this is an exaggerated example just for the purposes of this tutorial.
So what are fields anyway?
Well, one field is made up of odd horizontal lines in a frame, i.e. lines 1, 3, 5, etc.
This is called the odd field, or the upper field, since it contains the upper lines of
the image.
The other field is made up of even horizontal lines in a frame, i.e. lines 2, 4, 6, etc.
This is called the even field, or the lower field, since it contains the lower lines of
the image.
Once the two fields are interlaced, you then are able to view the whole image of each of
the frames.
By the way, this happens one after the other, odd lines first, then even lines, which happens
so fast that our eyes don't really even have time to notice what's happening, so you end
up seeing the whole image of the frames.
Okay, so now that we have a real basic idea of what interlaced video is, let's take a
look at the problem I was having and how we can resolve it.
Alright, in this shot here, the SWAT guy is going to get pulled out of screen, and right
around the cursor is, from behind those boxes, an actor is going to come out and fire a gun
four times.
Now, the problem is, we only see one of the flares from one of the times he fires, not
all four times.
Let's take a quick look.
Just the one flare.
Okay, so why did this happen?
Well, I did a little searching on the web and came across this fantastic out of this world
forum called EmotionDV.com, and Dwayne from EmotionDV.com writes, my best guess is the
lower line resolution of the VHS image simply lost much of its flare, so it usually only
remains visible in a single field.
In other words, the flares are there, we just can't see them the way you're monitoring
the video.
So, how can we fix this?
Well, in Final Cut Pro, when the canvas window is set to 86%, it only shows one of the two
fields in a frame, so all we have to do is increase the canvas window to 100%.
Now, thinking I was being real smart, I decided to make a preset, boom, 100%.
So let's just take a look and see if that worked.
As you can see, it didn't.
What you have to do, even if you make a preset or not, is you go up to this little button
here, which allows you to select what size or percentage, rather, you want to be able
to view your clip in the canvas window, and just select anything below 100%, in this case
I'll just select 50, and then go back up to 100%, and the problem is solved.
Let's take a look.
And there we go.
It's all fixed.
Okay, there's two important things that you guys should be aware of.
One is that just because you've fixed it in Final Cut Pro does not mean that your exported
clip will have the same results.
So to make sure that it does, there's two options, one, just go down the timeline here
and double click on the clip, go up into effects, go into video filters, go down to video, and
select the interlace, and then export your film the way you want to, and it will work
fine.
The other way is on export, depending on what codecs you use, if it's available, make sure
that you select the interlace source video, and that will work as well.
Trust me, I've tested both of them, works fine, at least for my uses.
Another note of interest is that this problem only arises in Final Cut Pro, which is Apple's
professional version of nonlinear editing software.
Ironically, it does not work in their home version, I mean, you do not have the problem
in the home version iMovie HD.
Go figure.
Alright, well hopefully this helped a few of you, and thanks for watching, take care.
