Interlaced vs Progressive Editing

Interlaced or Progressive editing?

You've looked at your sources, you've seen the footage, you now have to ask yourself if you want to try removing the interlacing before you start editing or are you going to just edit it interlaced and deal with interlacing when it comes to distributing the video on the Internet. There are different pros and cons for each, so have a read through and decide for yourself.

Interlaced Footage:

All editing software is designed to edit interlaced footage. It's already in a correct format specification (i.e. NTSC video @ 29.97fps) and it means you can just edit the footage "as-is".

This is fine. You'll need to keep an eye on the field order, but you should know the field order of your source now. The main caveat with interlaced footage, in terms of editing, is that whenever you slow it down, or move it around, or apply certain effects, you need to deinterlace it. Deinterlacing can be good or bad depending on the method and, unfortunately, the method used by one of the most popular programs - Premiere - is pretty ugly. In fact, most stock deinterlacing features in editing programs are pretty crap so, during these parts, your video will look sub-standard. Also, if you need to edit a still in photoshop or use a mouth section for lip-synch you need to get sections that aren't interlaced otherwise things can get really messy.

The secondary issue with interlaced footage arises when you want to distribute your video for playback on a pc. Monitors are progressive devices and interlacing looks ugly, so you need to remove it somehow. It's not difficult to remove it after the video is edited but the best way of removing interlacing from NTSC video is to recover the original film frames using a process called Inverse Telecine or IVTC. This works best when done before you edit - it is very difficult to successfully IVTC after you have edited the source.

Progressive footage:

Some sources are already progressive, which is great. However, the best way to get progressive footage from an interlaced source, as I have mentioned, is by using Inverse Telecine (IVTC). This will detect the pattern in which full film frames have been converted to interlaced NTSC and try and reverse it. With certain sources it can work very very well. You can also have progressive frames by deinterlacing as well. We will talk more about the different methods later - right now you need to know what difference it will make to your editing.

Progressive frames can be moved around, have effects done to them and so on without having to worry about interlaced frames. It's also very easy to take a still from any frame you like in order to edit it without worrying about the horizontal lines - this is great for photoshop work, masking and all sorts of manual frame manipulation effects.

One thing I will point out, however, is that running IVTC on your footage will make it 23.976fps. If you are using Vegas video this is not a problem... if you are using Adobe Premiere however, it is a big problem Premiere cannot easily edit 23.976 fps and this is a very annoying truth. It can edit in 23.98fps but this mode has all sorts of synch issues and the final output is useless to everyone. Thankfully you can change it to 24fps and premiere can edit 24fps fine so it's not all bad - it just requires a little more preparation in advance.

23.976fps is no use for DV either as DV has to be 29.97fps (or 25fps for PAL DV). Cons also like things, often, to be the standard 29.97fps interlaced footage. Thankfully it's actually very very easy to convert 23.976fps video to 29.97fps, so again it's not all bad (you can see how to do that later).

I know it's confusing. On one hand you have lots of advantages with having progressive frames and on the other you have the problem of having to edit as 24fps if you use Premiere and 24fps not being an NTSC standard. Of course, if you are only interested in Internet distribution, then editing at 24fps is no problem whatsoever. If you do want to have a 23.976 fps or a 29.97fps video at any point then it is still possible and there are tricks to make it easier that we will look at later if you choose this method.

Worst case scenario is that you make a 24fps video and this needs to be converted to 29.97fps for a con. That's easy done, is described later, so don't worry about it.

Mixing footage types:

If you are making an interlaced video, it is not a problem to mix in progressive video and then export interlaced. You will not notice any quality loss issues - progressive footage can have any field order and will blend in perfectly. On a tv you wont even notice that they were different. However, you should never add interlaced footage to a video you are editing progressive, as the interlacing will stand out a mile on a monitor.

So, if you know which way you are going to edit your footage, choose your next option:

Making your footage Progressive (removing interlacing) or skip straight to...

Dealing With Aspect Ratios