Just when I thought I new how progressive and interlaced are working....

Question

Hey everyone.
I thought I new the difference between progressive and interlaced but I've still got a few questions. For the most part... i get it. Progressive is like 1 solid picture. Interlaced breaks up the picture into interlaced lines and 2 fields, odd and even . Great, that much I've got.
Here's my issues.
This is actually a compressor question but it starts off with Final Cut.
I shot some footage on Mini DV NTSC 29.97 interlaced.
When I edit it in Final Cut things look pretty good. I see a little interlacing in the preview window but that's ok, it's the preview window. I know there is a filter to de-interlace my footage but what is the option in my sequence settings of Field Dominance? There is an option of field Dominance- Lower, even and None. Lower and even I assume deal with interlacing fields. I assumed none meant progressive. What's the point of needing a filter if I can change the field dominance within my sequence settings? Does it do the same thing?
If I export this footage to compressor I use the H.264 codec from inside compressor.
I noticed that I can turn the Frame Controls tab of my setting on. I then have access to the resizing controls. Resize Filter... not sure what that is. Then Output fields. I change that to progressive. Which I assume deinterlaced everything... but then there is another option right below that to Deinterlace....? Didn't I just do that by saying their are no fields? On a final note after it exports and I go to look at the .mov... the footage is still interlaced.
One last thing with compressor. The above issues are all part of my setting inside of the inspector for the actual "codec" i have attached to the project. If I mouse click on the project itself... not the settings of the codec but the project itself, the information inside my inspector window changes. Now instead of Codec Settings I have A/V Attributes... there is an option there for Native Field Dominance? Which one do I change? How many field dominances are there? I have 1 in Final Cut another 1 in my AV Attributes of my project in compressor and a 3rd on in the codec settings.
I hope these questions make sense. They are confusing issues to me so I'm not quite sure how to ask them.
Thanks a lot.
-Drew

Answer 1

It's not surprising that you're confused. It's a pretty confusing subject. Hopefully, I can help you get some sense out of it.
Most of your questions stem from not quite understanding the definitions of "deinterlacing", "progressive frame rate", and "field dominance". Let's start with the last since it pertains to your first question.
When you have interlaced footage, you have 2 fields (as you noted) per frame. One field is drawn on the Odd (or Upper) scan lines of the TV. 1,3,5,7...down to 479. The other field takes the Even (or Lower) scan lines: 2,4,6,8...480. Together they are woven into a single frame.
The field dominance in your sequence settings determines which field is drawn first. DV and NTSC in general is Lower field dominant and if your footage is DV, you should not change this. Interlaced HD is typically Upper field dominant. Again, under most circumstances, this should not be changed. What will likely occur is a "tearing" of the image in movement, particularly noticed in pans or fast action. None draws each line successively which is how progressive footage needs to be interpreted.
However, progressive does NOT mean deinterlaced. Nor does deinterlaced mean progressive. If you use the deinterlace filter in FCP on your DV footage, you merely remove one field from your footage and REPLACE it with a copy of the field you kept. In other words, if you set the deinterlace for Upper, then the clip will copy the image in the Lower field and paste it into the Upper field. The footage will still be interlaced.
In Compressor, changing the Output to Progressive in the frame controls will make your interlaced footage progressive. This should always be done when the final viewing medium is a computer. You see, computer monitors always display thing progressively; they have trouble with interlacing frames. They are not built like TVs. If going to TV, then you want to keep it interlaced (unless you're going for the progressive look), as that is how standard def TVs are designed to view video.
The deinterlace option in Compressor is the same as the filter in FCP, but as you know now, that's not the same thing as making a file progressive.
Finally, the AV settings for the clip you placed in Compressor are the same as the sequence settings in FCP. They help the program determine how the file should be displayed. If you have DV footage, and you switch the dominance in that setting or in FCP, then you risk having your footage look jittery and generally no good.
I hope this clears things up for you a bit.
Andy